WO2018198836A1 - Power generation plant and operation method therefor - Google Patents

Power generation plant and operation method therefor Download PDF

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Publication number
WO2018198836A1
WO2018198836A1 PCT/JP2018/015593 JP2018015593W WO2018198836A1 WO 2018198836 A1 WO2018198836 A1 WO 2018198836A1 JP 2018015593 W JP2018015593 W JP 2018015593W WO 2018198836 A1 WO2018198836 A1 WO 2018198836A1
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WO
WIPO (PCT)
Prior art keywords
feed water
boiler
heating
steam
amount
Prior art date
Application number
PCT/JP2018/015593
Other languages
French (fr)
Japanese (ja)
Inventor
雄太 小澤
吉田　章人
卓一郎 大丸
太田　裕二
Original Assignee
三菱日立パワーシステムズ株式会社
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Application filed by 三菱日立パワーシステムズ株式会社 filed Critical 三菱日立パワーシステムズ株式会社
Publication of WO2018198836A1 publication Critical patent/WO2018198836A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/34—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating
    • F01K7/44—Use of steam for feed-water heating and another purpose
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
    • F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B33/00—Steam-generation plants, e.g. comprising steam boilers of different types in mutual association
    • F22B33/18—Combinations of steam boilers with other apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/12—Control devices, e.g. for regulating steam temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/32—Feed-water heaters, i.e. economisers or like preheaters arranged to be heated by steam, e.g. bled from turbines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • F22G5/12—Controlling superheat temperature by attemperating the superheated steam, e.g. by injected water sprays

Definitions

  • the present invention relates to a power plant provided with a boiler for heating feed water that heats boiler feed water, and an operation method thereof.
  • Patent Document 1 discloses that power generation efficiency is improved by heating boiler feed water using steam or hot water obtained in a large incinerator.
  • biomass-derived biomass fuels such as woody, agricultural, and sludge are carbon neutral that does not emit carbon dioxide, which is a global warming gas, because carbon dioxide is taken in during the growth of biomass.
  • Various uses have been studied. For example, a power plant that performs co-firing in a boiler using fossil fuel and biomass fuel has been studied.
  • This invention is made
  • the purpose is to provide.
  • carbon-neutral biomass fuel is used to reduce environmental impact
  • the present invention increases the use ratio of biomass fuel to reduce fossil fuel consumption and reduce carbon dioxide emissions that do not become carbon-neutral.
  • An object of the present invention is to provide a power plant that can be operated and a method for operating the power plant.
  • a power plant includes a boiler including an economizer and a superheater, a steam turbine driven by steam generated in the boiler, a generator driven by the steam turbine, A feed water heating boiler for heating feed water supplied to the boiler, a feed water heating heat exchanger for exchanging heat between the heating fluid generated in the feed water heating boiler and the feed water supplied to the boiler, and the feed water heating A control unit that controls the heating amount of the feed water by the boiler, and the control unit controls the heating amount of the feed water by the amount of heat of the heating fluid output from the boiler for heating the feed water.
  • the enthalpy (heat amount per unit flow rate) of the feed water supplied to the boiler is increased, and the turbine efficiency is improved and the power generation efficiency for fossil fuel energy ( Hereinafter, it is simply referred to as “power generation efficiency”).
  • power generation efficiency since it decided to control the heating amount of the feed water by the boiler for feed water heating, it can respond to the output change of a boiler, or the property fluctuation
  • control unit calculates the amount of heat of the heating fluid from the temperature, pressure, and flow rate of the heating fluid, and the control unit calculates the amount of difference from a predetermined set value. Control the heating amount of the water supply.
  • control unit includes a steam control valve that discharges a part of the steam generated by the feed water heating boiler and / or the steam generated by the feed water heating boiler.
  • the spray water supply means which supplies spray water with respect to is controlled.
  • the heating amount of the feed water supplied to the boiler can be reduced by adjusting a part of the generated steam. it can. Moreover, by supplying spray water to the generated steam of the feed water heating boiler, the heating amount of the feed water supplied to the boiler can be reduced and adjusted. Thereby, even if it is a case where the property of the fuel thrown into a boiler for feed water heating changes, the heating amount of the feed water heated by the boiler for feed water heating can be adjusted to a desired value.
  • the power plant includes a feed water heater that heats the feed water with steam extracted from the steam turbine, and the control unit removes a part of the steam generated in the feed water heating boiler.
  • the control for controlling the extraction amount of steam supplied to the feed water heater is compared, and the control with the lower temperature of the feed water heated by the feed water heating heat exchanger is selected.
  • control unit controls the amount of steam extracted based on the strength of the turbine blades of the steam turbine.
  • the power plant includes a superheater spray that controls a temperature of superheated steam supplied from the superheater, and the control unit is configured to control the superheater based on a change amount of the heating amount. Controls the spray amount of the spray.
  • the power plant includes a feed water heater that extracts steam from the steam turbine and heats the feed water
  • the control unit has a feed water temperature heated by the feed water heat boiler. In response, the extraction amount of steam supplied to the feed water heater is controlled.
  • the amount of steam in the feed water heater is controlled by adjusting the amount of steam extracted from the steam turbine, and the temperature of the feed water supplied to the boiler is controlled. Since the steam extraction amount is controlled based on the feed water temperature heated by the feed water heating boiler, the feed water temperature supplied to the boiler can be controlled to a desired value.
  • control unit controls the heating amount so that the outlet water temperature of the economizer is less than the saturation temperature and close to the saturation temperature.
  • the heating amount of the feed water heating boiler is controlled so that the outlet water temperature of the economizer is less than the saturation temperature that does not vaporize and close to the saturation temperature, the feed water can be heated as much as possible.
  • the temperature that is lower than the saturation temperature and close to the saturation temperature is a temperature that is lower than the saturation temperature by several degrees C (for example, 2 degrees C) to about 10 degrees C.
  • the enthalpy of water supply can be increased as much as possible so that the economizer outlet water temperature does not vaporize, turbine efficiency can be improved and power generation efficiency can be improved, and fossil fuel input to the boiler can be reduced.
  • the amount of carbon dioxide that does not become carbon neutral can be reduced.
  • the power plant includes an exhaust gas treatment device that treats the exhaust gas discharged from the boiler, and the control unit is less than an upper limit temperature of the exhaust gas supplied to the exhaust gas treatment device and The heating amount is controlled so that the temperature is close to the upper limit temperature.
  • an upper limit temperature of exhaust gas to be supplied is defined. It is possible to control to increase the heating amount of the feed water heating boiler so that the exhaust gas temperature is lower than the upper limit temperature and close to the upper limit temperature.
  • the exhaust gas temperature that is lower than the upper limit temperature and close to the upper limit temperature is, for example, several degrees Celsius (for example, 2 degrees Celsius) to several tens of degrees from the upper limit temperature of the operating temperature of the equipment installed downstream of the exhaust gas flow, such as the catalyst temperature of the denitration device.
  • the temperature is lower by about °C. Since the temperature is lower than the upper limit temperature of the exhaust gas, the water supply can be heated as much as possible. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved.
  • the feed water heating boiler is a biomass boiler that uses biomass fuel as the main fuel.
  • a power plant operating method includes a boiler having an economizer and a superheater, a steam turbine driven by steam generated in the boiler, and a generator driven by the steam turbine.
  • a feed water heating boiler that heats the feed water supplied to the boiler, a feed water heating heat exchanger that exchanges heat between the heating fluid generated in the feed water heating boiler and the feed water supplied to the boiler, The feed water heating boiler controls the amount of heating by which the feed water is heated.
  • the feed water heating boiler Since the heating amount of the feed water heating boiler is controlled, the feed water can be heated while suppressing the influence on the operation performance of the boiler.
  • the biomass fuel is exclusively fired in the feed water heating boiler without co-firing the biomass fuel in the boiler, so the use ratio of the biomass fuel can be increased.
  • FIG. 1 shows a power plant 1 according to an embodiment.
  • the power plant 1 includes a boiler 3, a steam turbine 5, and a biomass boiler (feed water heating boiler) 7.
  • the boiler 3 includes a burner 11 that forms a flame using fossil fuel such as coal or oil in the furnace 10 of the boiler body 3a.
  • the furnace wall forming the furnace 10 is a water-cooled wall 12 composed of heat transfer tubes and fins, and water heated by the water-cooled wall 12 is guided to a steam drum 15.
  • a water drum 14 is provided on the vertically lower side of the water cooling wall 12. Water in the steam drum 15 is guided to the water drum 14 by the circulation pump 20 and water is supplied to the water cooling wall 12.
  • a subcritical pressure boiler having a drum is taken as an example, but the present invention can also be applied to a supercritical pressure boiler having no drum.
  • the combustion exhaust gas generated by the flame of the burner 11 flows vertically upward of the furnace 10 and is guided to the superheater 13.
  • a reheater 17 and an economizer 18 are provided in this order on the downstream side of the combustion exhaust gas flow of the superheater 13.
  • an economizer outlet pipe 22 through which water after being heated by the economizer 18 circulates is connected.
  • the economizer outlet pipe 22 is provided with an economizer outlet temperature sensor 22T and an economizer outlet pressure sensor 22P. The measured values of these sensors 22T and 22P are sent to the control unit 30.
  • a water supply pipe 24 for supplying water (water) is connected to the economizer 18. As will be described later, the feed water passing through the feed water pipe 24 is heated by steam generated in the biomass boiler 7 and then supplied to the economizer 18.
  • a temperature sensor 58T is provided in the water supply pipe 24 on the inlet side of the economizer 18. The measured value of the temperature sensor 58T is sent to the control unit 30.
  • a combustion exhaust gas temperature sensor 25T that measures the temperature of the combustion exhaust gas after passing through the economizer 18 is provided on the downstream side of the combustion exhaust gas flow that has passed through the economizer 18. The measured value of the combustion exhaust gas temperature sensor 25T is sent to the control unit 30. The combustion exhaust gas after passing through the combustion exhaust gas temperature sensor 25T is led to a denitration device (not shown) provided for removing NOx in the combustion gas at a midway position of the exhaust gas duct connected to the boiler body 3a. It is burned.
  • the denitration device is a selective catalytic reduction denitration device using ammonia, and an upper limit temperature (for example, about 400 ° C. to 420 ° C.) is determined in relation to the catalytic reaction temperature. Therefore, based on the temperature of the combustion exhaust gas temperature sensor 25T, for example, the control unit 30 adjusts the amount of heat exchange in the boiler 3 so as not to exceed the upper limit temperature of the denitration device, thereby controlling the combustion exhaust gas temperature.
  • the combustion exhaust gas that has passed through the denitration device is, for example, SOx etc. removed by a desulfurization device (not shown) in order to remove SOx in the combustion gas, and further, a dust treatment device and an induction blower not shown on the downstream side Etc. are provided as necessary, and discharged from the chimney at the downstream end of the exhaust gas duct to the atmosphere.
  • the superheater 13 is provided with a superheater spray 27.
  • a superheater spray 27 By injecting water or steam from the superheater spray 27, the superheated steam flowing in the superheater 13 is quickly cooled and controlled to a temperature within a predetermined range.
  • a part of the outlet water of the economizer 18 is used as the water used in the superheater spray 27.
  • the water injection amount and the injection timing of the superheater spray 27 are controlled by the control unit 30.
  • FIG. 1 schematically shows the installation position of the superheater spray 27, but a more specific installation position will be described with reference to FIG.
  • the superheater 13 includes, for example, a primary superheater 13a, a secondary superheater 13b, and a tertiary superheater 13c.
  • the superheater spray 27 is provided between the primary superheater 13a and the secondary superheater 13b, and between the secondary superheater 13b and the tertiary superheater 13c, respectively. Inject to reduce the superheated steam temperature step by step.
  • water spray is performed at the outlet of the primary superheater 13a so as to be the primary superheater outlet set temperature
  • water spray is performed at the outlet of the secondary superheater 13b so as to be the secondary superheater outlet set temperature.
  • a reheater spray may be provided for the reheater 17 as well.
  • the water injection amount and the injection timing of the reheater spray are also controlled by the control unit 30.
  • the steam turbine 5 includes, for example, a high-pressure turbine 34, an intermediate-pressure turbine 35, and a low-pressure turbine 36.
  • the generator 37 is rotationally driven by the rotational power generated in the turbines 34, 35, and 36, and power is generated.
  • the main steam pipe 32 is connected to the inlet of the high-pressure turbine 34.
  • a high pressure turbine outlet pipe 38 is connected to the exhaust side of the high pressure turbine 34.
  • the downstream end of the high-pressure turbine outlet pipe 38 is connected to the reheater 17 so that steam that has been subjected to predetermined expansion by the high-pressure turbine 34 and rotationally driven the turbine is guided to the reheater 17. It has become.
  • a reheat steam supply pipe 40 for supplying reheat steam to the intermediate pressure turbine 35 is provided between the steam outlet side of the reheater 17 and the intermediate pressure turbine 35.
  • the intermediate pressure turbine outlet pipe 42 is connected to the exhaust side of the intermediate pressure turbine 35.
  • the downstream end of the intermediate-pressure turbine outlet pipe 42 is connected to the inlet of the low-pressure turbine 36, and steam that has been subjected to predetermined expansion in the intermediate-pressure turbine 35 and rotationally driven the turbine is guided to the low-pressure turbine 36. It is like that.
  • a low-pressure turbine outlet pipe 44 is connected to the exhaust side of the low-pressure turbine 36.
  • the downstream end of the low-pressure turbine outlet pipe 44 is connected to a condenser 46.
  • the steam is cooled to a vacuum by a cooling water (not shown) and is condensed and liquefied.
  • the condensate liquefied by the condenser 46 becomes feed water and is led to the low-pressure feed water heater 50 by the condensate pump 48.
  • the feed water from the condensate is heated by the low-pressure steam guided from the low-pressure turbine 36.
  • the feed water heated by the low pressure feed water heater 50 is guided to the first intermediate pressure feed water heater 52a and the second intermediate pressure feed water heater 52b through the feed pump 51, and is extracted from the intermediate pressure turbine 35. Heated by steam.
  • the feed water heated by each of the medium pressure feed water heaters 52a and 52b is guided to the first high pressure feed water heater 54a and the second high pressure feed water heater 54b.
  • the high-pressure steam guided to the first high-pressure feed water heater 54a is guided via the first high-pressure extraction pipe 55a.
  • the first high pressure extraction pipe 55a is provided with a first high pressure extraction valve 56a whose opening degree is controlled by the control unit 30.
  • the high-pressure steam guided to the second high-pressure feed water heater 54b is guided via the second high-pressure extraction pipe 55b.
  • the second high pressure extraction pipe 55b is provided with a second high pressure extraction valve 56b whose opening degree is controlled by the control unit 30.
  • the first high-pressure extraction pipe 55a is connected to the upstream side (high-pressure side) of the high-pressure turbine 34 relative to the second high-pressure extraction pipe 55b.
  • the pressure of the high-pressure steam to be applied is higher than the pressure of the high-pressure steam guided by the second high-pressure extraction pipe 55b.
  • FIG. 3 shows the opening degrees of the high-pressure bleed valves 56a and 56b with respect to the load of the boiler 3 as an example of the present embodiment.
  • the map (load program) shown in FIG. 3 is stored in the storage unit of the control unit 30, and the valve opening is set in advance according to the load.
  • both the high-pressure extraction valves 56a and 56b are fully closed.
  • both the high pressure bleed valves 56a and 56b are fully opened.
  • the load area for switching between fully closed and fully opened is set to be different between the first high pressure bleed valve 56a and the second high pressure bleed valve 56b, thereby improving the controllability of heating of the feed water.
  • the first high pressure bleed valve 56a operates on the higher load side than the second high pressure bleed valve 56b.
  • the high pressure extraction valves 56a and 56b are controlled in the closing direction regardless of the load of the boiler 3 instead of the map shown in FIG.
  • each feed water heater 50, 52a, 52b, 54a, 54b is sequentially supplied to the low pressure stage feed water heaters 50, 52a, 52b, 54a, as indicated by broken line arrows in FIG. 54b and finally collected by the condenser 46.
  • the feed water after being heated by the high-pressure feed water heaters 54a and 54b is guided to the feed water heating heat exchanger 60 through the feed water pipe 24.
  • the feed water heating heat exchanger 60 the feed water is heated by the steam guided from the biomass boiler 7 to the heating heat transfer tube 61.
  • the steam is supplied to the heating heat transfer pipe 61, and the heating steam supply pipe 62 is passed through the heating heat transfer pipe 61 to perform drainage.
  • a return pipe 64 and a return pump 65 for returning the drain water to the biomass boiler 7 are provided.
  • the heating steam supply pipe 62 includes a heating steam temperature sensor 62T that measures the temperature of the heating steam, a heating steam pressure sensor 62P that measures the pressure of the heating steam, and a heating that measures the flow rate of the heating steam.
  • a steam flow rate sensor 62F is provided.
  • the measured values of the sensors 62T, 62P, and 62F are sent to the control unit 30.
  • a biomass boiler fluid calorific value which is a calorific value of steam (heating fluid) generated in the biomass boiler 7 and which is a calorific value output to the feed water heating heat exchanger 60 is calculated. Specifically, as shown in FIG.
  • step S00 when the calorie calculation of the generated steam of the biomass boiler 7 is started (step S00), the temperature, pressure and flow rate of the generated steam are obtained from the sensors 62T, 62P, 62F ( Step S01). Next, the enthalpy of the generated steam is calculated from the obtained temperature and pressure according to the steam table (step S02). The steam table is stored in the storage unit of the control unit 30. Then, the calorific value of the generated steam is obtained by multiplying the enthalpy by the obtained flow rate (step S03), and the calculation of the biomass boiler fluid calorific value is terminated (step S04). The biomass boiler fluid calorie obtained in this way is used to control a steam control valve 72 described later.
  • a return pump 65 is provided in the middle of the return pipe 64 so that drain water is sent to the biomass boiler 7 by the return pump 65 and circulates between the biomass boiler 7 and the heat exchanger 60 for heating the feed water. It has become.
  • a feed water bypass pipe 67 is provided so as to bypass the feed water heating heat exchanger 60.
  • the water supply bypass pipe 67 is provided with a water supply bypass valve 68 whose opening and closing is controlled by the control unit 30.
  • the feed water bypass valve 68 is fully closed when the feed water heating heat exchanger 60 is used, and is fully opened when the feed water heating heat exchanger 60 is not used.
  • a temperature sensor 57 ⁇ / b> T for measuring a feed water heating heat exchanger inlet temperature is provided in the feed water pipe 24 on the upstream side of the feed water bypass pipe 67. The measured value of the temperature sensor 57T is sent to the control unit 30.
  • the biomass boiler 7 generates steam by burning biomass fuel.
  • the output of the biomass boiler 7 is controlled by the control unit 30. Specifically, the supply amount of biomass fuel input to the biomass boiler 7, the flow rate of combustion air, the supply amount of generated steam, and the like are controlled by the control unit 30.
  • the biomass boiler 7 is provided with a steam control valve 72 whose opening degree is controlled by the control unit 30. Part of the steam generated by the biomass boiler 7 is discharged to the condenser 46 via the steam control valve 72.
  • the discharge destination of the steam is not limited to the condenser 46, and may be another cooling device or atmospheric discharge, for example.
  • the heating steam supply pipe 62 may be provided with a heating steam spray (spray water supply means) 73. By injecting water into the heating steam supply pipe 62 from the heating steam spray 73, the steam temperature is lowered. The starting and stopping of the heating steam spray 73 is controlled by the control unit 30.
  • the water is returned to the upstream side of the return pump 65 of the return pipe 64 by a water supply line (not shown). A part of the condensate of the water device 46 may be supplied.
  • the control unit 30 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium.
  • a series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing.
  • the program is preinstalled in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Etc. may be applied.
  • the computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.
  • the power plant 1 having the above-described configuration operates as follows.
  • the superheated steam generated in the superheater 13 of the boiler 3 is guided to the high-pressure turbine 34 of the steam turbine 5, and after being driven to rotate, is guided to the reheater 17.
  • the steam guided to the reheater 17 is reheated by the boiler 3 and guided to the intermediate pressure turbine 35 as reheated steam.
  • the reheat steam rotates the intermediate pressure turbine 35 and then guides it to the low pressure turbine 36 to rotate the low pressure turbine 36.
  • the generator 37 is rotationally driven by the rotational power thus obtained, and power generation is performed.
  • the steam that has been subjected to predetermined expansion in the low-pressure turbine 36 and rotationally driven the turbine becomes condensate in the condenser 46, and sequentially passes through each of the feed water heaters 50, 52b, 52a, 54b, 54a as feed water. To be heated. Thereafter, the feed water is further heated by the feed water heating heat exchanger 60 and supplied to the economizer 18 of the boiler 3.
  • the heating amount of the feed water in the feed water heating heat exchanger 60 is adjusted by controlling the output of the biomass boiler 7 by the control unit 30. Specifically, it is as follows.
  • Control is performed so that the outlet temperature of the water heated by the economizer 18 does not evaporate beyond the saturation temperature. Thereby, the water supply temperature as high as possible is realized while preventing the water at the outlet of the economizer 18 from becoming steam.
  • the control unit 30 obtains the saturation temperature T1 from the measured pressure of the economizer outlet pressure sensor 22P and the measured temperature of the temperature sensor 22T.
  • a temperature close to the saturation temperature below the saturation temperature T1 within a range of a predetermined value (for example, 2 ° C. to 10 ° C.) is set as an economizer outlet temperature setting value T1set, and the control unit 30 Feedback-controls the output of the biomass boiler 7. Thereby, the temperature of water supply is made as high as possible so that the outlet water temperature of the economizer 18 is not vaporized, and the enthalpy of water supply is increased as much as possible.
  • control is performed so as not to exceed the upper limit temperature T2 determined from the catalytic reaction temperature of the denitration apparatus.
  • the control unit 30 obtains the temperature measured by the combustion exhaust gas temperature sensor 25T and sets the temperature below the upper limit temperature T2 within a predetermined value (for example, 5 ° C. to several tens of degrees Celsius (for example, 50 ° C.)) as the combustion exhaust gas temperature set value T2set.
  • the control unit 30 feedback-controls the output of the biomass boiler 7 so that the combustion exhaust gas temperature set value T2set is obtained. Thereby, the temperature of the feed water is increased as much as possible so that the combustion exhaust gas that has passed through the economizer 18 does not exceed the upper limit temperature, and the enthalpy of the feed water is increased as much as possible.
  • the control unit 30 controls the heating amount (for example, steam amount, pressure, temperature, and heat output amount) from the biomass boiler 7 so as to satisfy both the control based on the economizer outlet temperature and the control based on the combustion exhaust gas temperature.
  • FIG. 5 shows the heating amount control of the biomass boiler 7 using the steam control valve 72.
  • the biomass boiler fluid calorific value set value which is the calorific value set value output from the biomass boiler 7 to the feed water heating heat exchanger 60, and the calculation described with reference to FIG. 4 were obtained.
  • the opening degree of the steam control valve 72 is controlled by advance control or feedback control according to this difference amount, and for feed water heating corresponding to the difference amount among the steam generated by the biomass boiler 7 Steam not supplied to the heat exchanger 60 is supplied to the condenser 46. By controlling the generated steam flow rate of the biomass boiler 7, the biomass boiler fluid heat quantity is quickly controlled.
  • the biomass boiler fluid calorific value set value is calculated in advance from the heat balance of the entire power plant 1 and stored in the storage unit of the control unit 30.
  • the amount of heating is controlled to increase by increasing the amount of biomass fuel supplied to the biomass boiler 7, the flow rate of combustion air, and the like. If the calculated value of biomass boiler fluid calorie is less than the set value of biomass boiler fluid calorie, such as when there is a large change in the calorific value of biomass fuel, increase the frequency at which the calculated value of the biomass boiler fluid calorific value increases slightly.
  • the time constant of the control unit 30 for the output of the biomass boiler 7 may be changed.
  • the heating steam spray 73 may be started and stopped.
  • the biomass boiler fluid heat quantity can be quickly controlled by the heating steam spray 73. Further, the steam control valve 72 and the heating steam spray 73 may be used in combination.
  • control unit 30 controls the high pressure extraction valves 56a and 56b as follows.
  • the biomass boiler 7 is not charged, that is, when the feed water is not heated by the feed water heating heat exchanger 60, the high pressure bleed valve according to the load of the boiler 3 according to the load program in the map shown in FIG. The opening degree of 56a, 56b is controlled.
  • the high pressure extraction valves 56a and 56b are controlled to be closed, that is, the amount of extraction of high pressure steam is reduced.
  • the amount of heating from the biomass boiler 7 is calculated by setting the biomass boiler fluid calorific value obtained from the heating steam temperature sensor 62T, the heating steam pressure sensor 62P, and the heating steam flow rate sensor 62F to the biomass boiler fluid calorific value. It is controlled by the control unit 30 so as to be a value.
  • the control unit 30 calculates so as to satisfy both the control based on the economizer outlet temperature and the control based on the combustion exhaust gas temperature.
  • the high-pressure extraction valves 56a and 56b are fully closed, and the extraction amount of the high-pressure steam is set to zero.
  • the timing at which the high-pressure extraction valves 56a and 56b are fully closed at this time is preferably performed based on a control map in which the relationship with the heating amount from the biomass boiler 7 is determined in advance.
  • the opening control of the high pressure extraction valves 56a and 56b is performed as described above, it is performed as follows. As shown in FIG. 6, in the control unit 30, the difference between the economizer outlet temperature set value (in this embodiment, the economizer outlet temperature set value T1set) and the economizer outlet temperature measured value obtained from the economizer outlet temperature sensor 22T is calculated. Therefore, the opening degree of the high pressure extraction valves 56a and 56b is controlled by the preceding control or the feedback control according to the difference amount.
  • the flow rate of the steam flowing through the high-pressure turbine 34 can be increased within the specified range of mechanical strength, and the turbine efficiency can be improved.
  • the specified range of mechanical strength is set.
  • the strength of the turbine blades of the high pressure turbine 34 is taken into account. That is, the strength of the turbine blade is designed to have durability against the differential pressure applied before and after the turbine blade.
  • the high-pressure bleed valve 56a is considered in consideration of the load of the boiler 3 so that the differential pressure does not exceed the allowable value on the turbine blade strength.
  • 56b that is, the amount of decrease in the amount of high-pressure steam extraction is determined. For example, when the high pressure bleed valves 56a and 56b are fully closed, the turbine strength at the MCR point (boiler maximum continuous evaporation amount) is considered. If the turbine strength is sufficient even when the high pressure extraction valves 56a and 56b are fully closed at the MCR point, the high pressure extraction valves 56a and 56b can be fully closed even when the load is 100%. If the turbine strength is not sufficient, the reduction amount of the high-pressure steam extraction amount is determined in consideration of the turbine strength when the load is 100%, and the openings of the high-pressure extraction valves 56a and 56b are set.
  • the control unit 30 controls the superheater spray 27 when the amount of heating of the biomass boiler 7 changes or when the amount of high-pressure steam extracted by the high-pressure extraction valves 56a and 56b changes.
  • the heating amount of the biomass boiler 7 changes (for example, emergency stop of the biomass boiler 7 or change in the calorific value of the biomass fuel)
  • the temperature of the main steam exiting the superheater 13 may change.
  • the balance between the superheater 13 and the reheater 17 may change when the amount of high-pressure steam extracted to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b changes, the superheater spray may change.
  • the main steam temperature and the reheat steam temperature are quickly controlled within a range of appropriate values.
  • a reheater spray is provided, it is preferably controlled in cooperation with the superheater spray 27. Therefore, when heating feed water with the biomass boiler 7, compared with the case where feed water is not heated with the biomass boiler 7, the amount of cooling heat is required, and the control range of the injection amount of the superheater spray 27 and the reheater spray is required. Therefore, it is more preferable that the superheater spray 27 or the reheater spray having a control range of the injection amount corresponding to this is adopted.
  • step S1 activation control of the biomass boiler 7 will be described with reference to FIG.
  • step S2 the load of the boiler 3 is equal to or greater than a certain level
  • the biomass boiler 7 is stopped, and high-pressure extraction for supplying high-pressure steam to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b.
  • step S2 the biomass boiler 7 is started as shown in step S2.
  • step S. 5 and 6 opening control of the steam control valve 72 and the high pressure extraction valves 56a and 56b is started.
  • step S3 the biomass boiler outlet steam temperature measured by the heating steam temperature sensor 62T provided in the heating steam supply pipe 62 flows into the feed water heating heat exchanger 60 measured by the temperature sensor 57T. It is judged whether it is more than predetermined value (alpha) rather than the water supply temperature to perform. If the condition of step S3 is satisfied, the process proceeds to step S4. If not satisfied, step S3 is repeated and the activation of the biomass boiler 7 is continued.
  • the predetermined value ⁇ is determined from the heat transfer characteristics of the feed water heating heat exchanger 60. To reduce the predetermined value ⁇ , it is necessary to increase the heat transfer area of the feed water heating heat exchanger 60, and the heat exchanger is large. Turn into. For example, the predetermined value ⁇ is set at 2 ° C. to 10 ° C., more preferably 2 ° C. to 5 ° C.
  • step S4 the feed water bypass valve 68 is closed, and the feed water is guided to the feed water heating heat exchanger 60. At this time, the control of the steam control valve 72 and the high pressure bleed valves 56a and 56b is continued.
  • the water supply pipe 24 is provided with a temperature sensor 58T that measures the temperature of the water supply inlet of the economizer 18.
  • the measured value of the temperature sensor 58T is sent to the control unit 30.
  • step S5 it is determined whether the feed water inlet temperature of the economizer 18 measured by the temperature sensor 58T is equal to or higher than a predetermined value ⁇ than the set temperature. If the condition of step S5 is satisfied, the process proceeds to step S6. If not satisfied, step S5 is repeated to wait for the temperature of the water supply inlet of the economizer 18 to rise.
  • the predetermined value ⁇ allows the opening of the high-pressure extraction valves 56a and 56b to be closed when the feed water inlet temperature of the economizer 18 exceeds the set temperature. When an unstable fluctuation occurs in the heat exchange amount of the exchanger 60, the opening degree control of the high pressure extraction valves 56a and 56b is affected. For example, the predetermined value ⁇ is set at 2 ° C. to 5 ° C.
  • step S6 the opening degree of the high pressure bleed valves 56a and 56b is controlled in the closing direction.
  • the steam control valve 72 not only the steam control valve 72 but also the high pressure bleed valves 56a and 56b continue to control the opening degree.
  • the extraction amount of the high-pressure steam is decreased, the steam flow rate of the steam turbine is increased within the specified range of the mechanical limit, and the turbine output is increased.
  • turbine efficiency can be improved. By improving the turbine efficiency, the power generation efficiency with respect to the load of the boiler 3 is improved.
  • step S7 Under the condition that the power generation output after heating to the feed water by the biomass boiler 7 does not change, the amount of fossil fuel input to the boiler 3 can be reduced, and the amount of carbon dioxide emissions that do not become carbon neutral can be reduced. Thus, the introduction of the biomass boiler 7 is completed and the start-up control is finished (step S7).
  • the heating amount of the biomass boiler 7 When the start-up control is finished, as described above, the heating amount of the biomass boiler 7, the extraction amount of the high-pressure steam supplied to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b, and the main heater 27 are used.
  • the appropriate boiler 3, biomass boiler 7 and steam turbine 5 By controlling the temperature of the steam, the appropriate boiler 3, biomass boiler 7 and steam turbine 5 are operated according to the load of the power plant 1.
  • the heating amount of the biomass boiler 7 is calculated as follows.
  • the calculated value of the biomass boiler fluid calorific value obtained from the heating steam temperature sensor 62T, the heating steam pressure sensor 62P, and the heating steam flow rate sensor 62F is the biomass boiler fluid calorific value set value. It is controlled by the control part 30 so that it may become.
  • This biomass boiler fluid calorific value set value is set in advance from the heat balance of the entire power plant 1 so as to satisfy both the control based on the economizer outlet temperature and the control based on the combustion exhaust gas temperature. Further, the extraction of the high-pressure steam supplied to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b is performed so that the differential pressure applied before and after the turbine blade does not exceed the allowable value on the strength of the turbine blade.
  • the bleed valves 56a and 56b are controlled by setting the opening in the closing direction. Further, when the amount of heating of the biomass boiler 7 and the amount of high-pressure steam extracted by the high-pressure extraction valves 56a and 56b change, the temperature of the main steam is quickly controlled by the superheater spray 27 to a range of appropriate values.
  • step S11 the load on the boiler 3 is equal to or greater than a certain level
  • the biomass boiler 7 is activated, the high pressure extraction valves 56a and 56b are closed, and the feed water bypass valve 68 is closed.
  • step S12 the biomass boiler 7 is stopped as shown in step S12.
  • the opening degree control of the steam control valve 72 shown in FIG. 5 is stopped, and the opening degree control of the high pressure extraction valves 56a and 56b shown in FIG. 6 is stopped.
  • the openings of the high pressure bleed valves 56a and 56b are controlled according to the load program shown in FIG.
  • step S13 it is determined whether the feed water inlet temperature of the economizer 18 measured by the temperature sensor 58T is lower than a value obtained by adding a predetermined value ⁇ to the set temperature. If the condition of step S13 is satisfied, the process proceeds to step S14. If not satisfied, step S13 is repeated.
  • the predetermined value ⁇ makes it possible to adjust the opening degree of the high pressure extraction valves 56a and 56b to be open when the feed water inlet temperature of the economizer 18 exceeds the set temperature. When an unstable fluctuation occurs in the heat exchange amount of the exchanger 60, the opening degree control of the high pressure extraction valves 56a and 56b is affected.
  • the predetermined value ⁇ is set at 2 ° C. to 5 ° C.
  • step S14 the high pressure extraction valves 56a and 56b are opened while the feed water bypass valve 68 is closed, and the opening degree is controlled according to the load program shown in FIG.
  • step S15 the feed water temperature at which the biomass boiler outlet steam temperature measured by the heating steam temperature sensor 62T provided in the heating steam supply pipe 62 flows into the feed water heating heat exchanger 60 measured by the temperature sensor 57T. It is determined whether the value is lower than a value obtained by adding a predetermined value ⁇ to the value. If the condition of step S15 is satisfied, the process proceeds to step S16. If not satisfied, step S15 is repeated.
  • the predetermined value ⁇ is determined from the heat transfer characteristics of the feed water heating heat exchanger 60. To reduce the predetermined value ⁇ , it is necessary to increase the heat transfer area of the feed water heating heat exchanger 60, and the heat exchanger is large. Turn into. For example, the predetermined value ⁇ is set at 2 ° C. to 10 ° C., more preferably 2 ° C. to 5 ° C.
  • step S16 the opening of the high pressure bleed valves 56a and 56b is opened, and the feed water bypass valve 68 is opened while the opening is controlled according to the load program shown in FIG. Thereby, feed water bypasses the heat exchanger 60 for feed water heating, and feed water heating by the biomass boiler 7 is stopped. Thus, the separation control of the biomass boiler 7 is completed (step S17).
  • the horizontal axis represents the output of the power plant 1 and the vertical axis represents the amount of heating given to the feed water from the biomass boiler 7. As shown in FIG. 9, the amount of heat is given to the feed water by the feed water heating by the biomass boiler 7. In the figure, the amount of heat given to the water supply when the output is 100% is expressed as a relative value with 1.0.
  • the horizontal axis indicates the output of the power plant
  • the power generation efficiency on the vertical axis indicates the power generation efficiency with respect to fossil fuel energy input to the power plant.
  • the power generation efficiency before the biomass boiler additional installation when the output is 100% is represented as 1.0 as a relative value.
  • the power generation efficiency is higher after the biomass boiler is added than before the biomass boiler is added.
  • the rate of increase in power generation efficiency is large.
  • the power generation efficiency in FIG. 7 is defined as (electric energy obtained) / (energy of fossil fuel to be input).
  • the turbine efficiency is defined as (obtained electric energy) / [(energy of steam flowing into the turbine) ⁇ (energy of steam flowing out of the turbine)].
  • 11A and 11B show the relationship and breakdown between the electric energy obtained by the power generation of the power plant 1 and the fuel energy to be input to the power plant 1 (boiler 3 and biomass boiler 7).
  • the case where the output of the power plant 1 is set to 50% in the middle is compared.
  • 11A shows before the biomass boiler 7 is additionally installed
  • FIG. 11B shows the biomass boiler 7 after the additional installation.
  • the electric energy obtained by the power generation before and after the additional installation of the biomass boiler 7 is the same amount, as shown in FIG. 11B (after the additional installation of the biomass boiler 7)
  • the fuel energy after the additional installation of the biomass boiler Reduces the amount of fossil fuel input and reduces carbon dioxide emissions that are not carbon neutral.
  • the steam generated in the biomass boiler 7 is used for heating the feed water supplied to the boiler 3, the amount of steam extracted from the steam turbine 5 is reduced (the amount of extraction reduced), and further supplied to the boiler 3.
  • the fossil fuel to be charged into the boiler 3 can be further reduced in accordance with the energy change caused by heating the feed water to a temperature lower than the saturation temperature within a predetermined range and close to the saturation temperature (increasing the feed water enthalpy), and carbon neutral.
  • the amount of carbon dioxide that cannot be reduced can be further reduced.
  • the enthalpy of the feed water supplied to the boiler 3 can be increased, turbine efficiency can be improved and power generation efficiency can be improved. Furthermore, since the heating amount of the biomass boiler 7 is controlled so that the outlet water temperature of the economizer 18 is less than the saturation temperature and close to the saturation temperature so as not to be vaporized, the water supply is heated as much as possible. Can do. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved. As a result, when generating the same amount of power as before the power generation efficiency is improved, the amount of fossil fuel input to the boiler 3 can be reduced, and the amount of carbon dioxide that does not become carbon neutral can be reduced.
  • the heating amount of the biomass boiler 7 is controlled so that the exhaust gas temperature is lower than the upper limit temperature of the denitration apparatus and close to the upper limit temperature, the feed water can be heated as much as possible. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved.
  • the heating amount of the feed water supplied to the boiler 3 is reduced by adjusting a part of the generated steam. be able to.
  • the feed water of the boiler 3 heated by the biomass boiler 7 is changed. The amount of heating can be adjusted to a desired value.
  • FIG. 12A and 12B show a comparative example regarding the presence or absence of control of the heating amount using the steam control valve 72.
  • FIG. FIG. 12A shows a case where the control of the steam control valve 72 or the heating steam spray 73 is not used
  • FIG. 12B shows the steam control valve 72 or heating so that the calculated value of the biomass boiler fluid calorific value becomes the biomass boiler fluid calorific value set value. This is a case where the control of the steam spray 73 is used.
  • FIG. 12A when the control of the steam control valve 72 or the heating steam spray 73 is not used, the pressure, temperature, and flow rate of steam (biomass boiler outlet fluid) generated in the biomass boiler 7 fluctuate with time.
  • the heat exchange amount in the feed water heating heat exchanger 60 varies according to the pressure, temperature, and flow rate. Accordingly, the amount of heat supplied to the economizer 18 at the inlet (ECO inlet water supplied) also varies depending on the pressure, temperature, and flow rate.
  • the amount of steam extracted from the steam turbine 5 is adjusted by the high-pressure extraction valves 56a and 56b to control the heating amount in the high-pressure feed water heaters 54a and 54b, and the feed water temperature supplied to the economizer 18 is controlled. And since it decided to control the extraction amount of the steam extracted from the steam turbine 5 based on the feed water temperature heated with the biomass boiler 7 in the feed water heating heat exchanger 60, the feed water temperature supplied to the economizer 18 Can be controlled to a desired value.
  • the strength of the turbine blades as a specified value range of the mechanical strength of the steam turbine 5 is designed to withstand the differential pressure applied before and after the turbine blades, and this differential pressure is the flow rate of steam flowing to the steam turbine 5.
  • the pressure difference is determined according to the amount of bleed air. Therefore, the steam extraction amount is controlled in consideration of the strength of the turbine blade. As a result, the amount of extraction can be reduced as much as possible in consideration of the strength of the turbine blades, the total steam flow flowing into the steam turbine 5 can be reduced, and the turbine efficiency can be further improved.
  • the temperature of the superheated steam supplied from the superheater 13 may fluctuate due to changes in the amount of heating of the biomass boiler 7 and the amount of steam extracted from the steam turbine 5.
  • the temperature of the steam pipes and turbine blades used under high temperature and high pressure can be quickly set within a specified value, and deterioration and damage can be suppressed. Can do.
  • the flow rate of the reheater spray that controls the temperature of the reheat steam supplied from the reheater 17 is also controlled, the temperature of the reheat steam can be easily controlled to a desired value. .
  • the heating amount of the biomass boiler 7 is controlled so that the outlet water temperature of the economizer 18 is less than the saturation temperature and close to the saturation temperature so as not to be vaporized, the feed water can be heated as much as possible. . Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved. As a result, when generating the same amount of power as before the power generation efficiency is improved, the amount of fossil fuel input to the boiler 3 can be reduced, and the amount of carbon dioxide that does not become carbon neutral can be reduced.
  • the heating amount of the biomass boiler 7 is controlled so that the exhaust gas temperature is lower than the upper limit temperature of the denitration apparatus and close to the upper limit temperature, the feed water can be heated as much as possible. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved.
  • the biomass boiler 7 that uses biomass fuel as the main fuel as an additional boiler that heats the feed water
  • the biomass fuel can be exclusively burned in the biomass boiler 7 without co-firing the biomass fuel in the boiler 3. Therefore, the usage ratio of biomass fuel to fossil fuel burned in the boiler 3 can be increased, and the amount of carbon dioxide that does not become carbon neutral can be reduced.
  • inexpensive biomass fuel containing a corrosive component can be used without affecting the combustion of the boiler 3 main body, and highly efficient power generation can be performed at a low fuel cost.
  • the opening control of the steam control valve 72 and the high pressure extraction valves 56a and 56b described with reference to FIGS. 5 and 6 can be modified as shown in FIG. That is, the difference between the biomass boiler fluid calorific value setting value, which is the calorific value set value output from the biomass boiler 7 to the feed water heating heat exchanger 60, and the biomass boiler fluid calorific value calculation value is calculated. Take the difference between the control amount for control or feedback control, the set value of the economizer outlet temperature, and the measured value of the economizer outlet temperature, and compare the control amount for the preceding control or feedback control according to this difference amount And select a low value.
  • the biomass boiler fluid calorific value setting value which is the calorific value set value output from the biomass boiler 7 to the feed water heating heat exchanger 60
  • the biomass boiler fluid calorific value calculation value is calculated. Take the difference between the control amount for control or feedback control, the set value of the economizer outlet temperature, and the measured value of the economizer outlet temperature, and compare the control amount for the
  • the opening degree of the steam control valve 72 and the high pressure extraction valves 56a and 56b is controlled.
  • priority is given to control on the side of lowering the temperature (heat amount) of the water supply system.
  • a lower value with a smaller control amount economizer steaming in which steam is generated in the economizer 18 can be prevented and the soundness of the equipment can be ensured.
  • the control of the economizer outlet temperature is instructed to lower the temperature by selecting a low value.
  • the heating amount of the biomass boiler 7 is controlled based on the outlet temperature 22T of the economizer 18, but the inlet temperature of the economizer 18 may be used instead of the outlet temperature 22T of the economizer 18. good.
  • the biomass boiler 7 was used as an additional steam generator for heating feed water, it is not always necessary to use biomass as fuel. For example, garbage or combustible waste can be used as the fuel.
  • the feed water heating heat exchanger 60 is arranged in series with respect to the feed water heaters 50, 52a, 52b, 54a, 54b, but at least any of the feed water heaters 50, 52a, 52b, 54a, 54b. It is good also as arrange

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Abstract

The present invention is equipped with: a boiler (3) having an economizer (18) and a superheater (13); a steam turbine (5) driven by steam generated by the boiler (3); a generator (37) driven by the steam turbine (5); a feed water heating boiler (7) for heating feed water supplied to the boiler (3); a heat exchanger (60) for heating the supply water by exchanging heat between the steam generated by the feed water heating boiler (7) and the feed water supplied to the boiler (3); and a control unit (30) for controlling the value of heating of the feed water by the feed water heating boiler (7).

Description

発電プラント及びその運転方法Power plant and operation method thereof
　本発明は、ボイラ給水を加熱する給水加熱用ボイラを備えた発電プラント及びその運転方法に関するものである。 The present invention relates to a power plant provided with a boiler for heating feed water that heats boiler feed water, and an operation method thereof.
　石炭や石油等の化石燃料を用いたボイラにより発生させた水蒸気を蒸気タービンに供給して蒸気タービンを回転駆動させ、この回転駆動により発電機により発電を行う発電プラントでは、発電効率の向上・化石燃料消費量の低減や、環境影響の更なる低減が求められている。環境影響の更なる低減とは、世界的に取り組みが行われている二酸化炭素排出量の削減などである。例えば、特許文献１には、大型焼却場で得られた蒸気や温水を用いてボイラ給水を加熱することで発電効率を向上させることが開示されている。 In a power plant where steam generated by a boiler using fossil fuels such as coal and oil is supplied to a steam turbine and the steam turbine is driven to rotate, and power is generated by the generator using this rotating drive, power generation efficiency is improved There is a need to reduce fuel consumption and environmental impact. Further reductions in environmental impact include reductions in carbon dioxide emissions that are being addressed globally. For example, Patent Document 1 discloses that power generation efficiency is improved by heating boiler feed water using steam or hot water obtained in a large incinerator.
特許第３６１１３２７号公報Japanese Patent No. 3611327
　しかし、特許文献１では、大型焼却場で得られた蒸気や温水によってボイラ給水を加熱して発電効率の向上を行っているが、大型焼却場から供給される蒸気や温水の熱量が一定であることを前提としている。したがって、大型焼却場の出力が変化すると、ボイラの運転性能に影響を及ぼすおそれがある。 However, in patent document 1, although boiler feed water is heated with the steam and warm water obtained in the large incineration plant, and the power generation efficiency is improved, the heat quantity of the steam and warm water supplied from the large incineration plant is constant. It is assumed that. Therefore, if the output of the large incinerator changes, there is a risk of affecting the operating performance of the boiler.
　一方、木質系や農業系・汚泥系などのバイオマス由来のバイオマス燃料は、バイオマスの成育過程において二酸化炭素を取り込むことから、地球温暖化ガスとなる二酸化炭素を排出しないカーボンニュートラルとされるため、その利用が種々検討されている。例えば、化石燃料とバイオマス燃料とを用いてボイラで混焼を行う発電プラントが検討されている。 On the other hand, biomass-derived biomass fuels such as woody, agricultural, and sludge are carbon neutral that does not emit carbon dioxide, which is a global warming gas, because carbon dioxide is taken in during the growth of biomass. Various uses have been studied. For example, a power plant that performs co-firing in a boiler using fossil fuel and biomass fuel has been studied.
　しかし、バイオマス燃料の良質なものは高価であり、化石燃料に対してコスト競争力の点で課題がある。また、バイオマス燃料の廉価なものは腐食成分を多く含むため実際にはボイラでは少量しか混焼ができない。さらに、ボイラの燃料供給設備や環境装置の技術的制約から混焼率には上限があり、ボイラの出力が低いときには一層にバイオマス燃料の投入量も少なくならざるを得ない。 However, high-quality biomass fuels are expensive, and there are problems in terms of cost competitiveness with respect to fossil fuels. In addition, since inexpensive biomass fuels contain many corrosive components, only a small amount can be mixed in a boiler. Furthermore, there is an upper limit to the mixed combustion rate due to technical limitations of boiler fuel supply facilities and environmental devices, and when the output of the boiler is low, the amount of biomass fuel input must be further reduced.
　本発明は、このような事情に鑑みてなされたものであって、ボイラの運転性能に影響を及ぼすことを抑制して給水を加熱するボイラ給水加熱用ボイラを備えた発電プラント及びその運転方法を提供することを目的とする。
　また、本発明は、環境影響の低減からカーボンニュートラルなバイオマス燃料を用いる場合には、バイオマス燃料の使用比率を高めて化石燃料の消費量を削減し、カーボンニュートラルとならない二酸化炭素の排出量を削減させることができる発電プラント及びその運転方法を提供することを目的とする。 This invention is made | formed in view of such a situation, Comprising: The power plant provided with the boiler for boiler feed water heating which suppresses affecting the driving performance of a boiler and heats feed water, and its operating method The purpose is to provide.
In addition, when carbon-neutral biomass fuel is used to reduce environmental impact, the present invention increases the use ratio of biomass fuel to reduce fossil fuel consumption and reduce carbon dioxide emissions that do not become carbon-neutral. An object of the present invention is to provide a power plant that can be operated and a method for operating the power plant.
　上記課題を解決するために、本発明の発電プラント及びその運転方法は以下の手段を採用する。
　すなわち、本発明の一態様にかかる発電プラントは、エコノマイザ及び過熱器を備えるボイラと、該ボイラにて生成された蒸気によって駆動される蒸気タービンと、該蒸気タービンによって駆動される発電機と、前記ボイラに供給される給水を加熱する給水加熱用ボイラと、前記給水加熱用ボイラで発生した加熱流体と前記ボイラへ供給される前記給水とを熱交換する給水加熱用熱交換器と、該給水加熱用ボイラによる前記給水の加熱量を制御する制御部とを備え、前記制御部は、前記給水加熱用ボイラにより出力される前記加熱流体の熱量によって前記給水の加熱量を制御する。 In order to solve the above problems, the power generation plant and the operation method thereof according to the present invention employ the following means.
That is, a power plant according to an aspect of the present invention includes a boiler including an economizer and a superheater, a steam turbine driven by steam generated in the boiler, a generator driven by the steam turbine, A feed water heating boiler for heating feed water supplied to the boiler, a feed water heating heat exchanger for exchanging heat between the heating fluid generated in the feed water heating boiler and the feed water supplied to the boiler, and the feed water heating A control unit that controls the heating amount of the feed water by the boiler, and the control unit controls the heating amount of the feed water by the amount of heat of the heating fluid output from the boiler for heating the feed water.
　ボイラに供給される給水を給水加熱用ボイラによって加熱することで、ボイラに供給される給水のエンタルピ（単位流量あたりの熱量）を増大させて、タービン効率を向上して化石燃料エネルギに対する発電効率（以下、単に「発電効率」という。）を向上させることができる。そして、給水加熱用ボイラによる給水の加熱量を制御することとしたので、ボイラの出力変化や給水加熱用ボイラに投入される燃料の性状変動に対して対応することができる。 By heating the feed water supplied to the boiler with a feed water heating boiler, the enthalpy (heat amount per unit flow rate) of the feed water supplied to the boiler is increased, and the turbine efficiency is improved and the power generation efficiency for fossil fuel energy ( Hereinafter, it is simply referred to as “power generation efficiency”). And since it decided to control the heating amount of the feed water by the boiler for feed water heating, it can respond to the output change of a boiler, or the property fluctuation | variation of the fuel thrown into a boiler for feed water heating.
　さらに、本発明の一態様にかかる発電プラントでは、前記制御部は、前記加熱流体の熱量を、該加熱流体の温度、圧力及び流量から算出し、所定の設定値との差分量に応じて前記給水の加熱量を制御する。 Furthermore, in the power plant according to one aspect of the present invention, the control unit calculates the amount of heat of the heating fluid from the temperature, pressure, and flow rate of the heating fluid, and the control unit calculates the amount of difference from a predetermined set value. Control the heating amount of the water supply.
　さらに、本発明の一態様にかかる発電プラントでは、前記制御部は、前記給水加熱用ボイラが発生した蒸気の一部を排出する蒸気制御弁、及び／又は、前記給水加熱用ボイラが発生した蒸気に対してスプレイ水を供給するスプレイ水供給手段を制御する。 Furthermore, in the power plant according to one aspect of the present invention, the control unit includes a steam control valve that discharges a part of the steam generated by the feed water heating boiler and / or the steam generated by the feed water heating boiler. The spray water supply means which supplies spray water with respect to is controlled.
　給水加熱用ボイラが発生した蒸気の一部を排出する蒸気制御弁を開とすることで、発生蒸気の一部を排出してボイラに供給される給水の加熱量を減少させて調整することができる。また、給水加熱用ボイラの発生蒸気に対してスプレイ水を供給することによって、ボイラに供給される給水の加熱量を減少させて調整することができる。これにより、給水加熱用ボイラに投入される燃料の性状が変動した場合であっても、給水加熱用ボイラによって加熱される給水の加熱量を所望値に調整することができる。 By opening the steam control valve that discharges a part of the steam generated by the feed water heating boiler, the heating amount of the feed water supplied to the boiler can be reduced by adjusting a part of the generated steam. it can. Moreover, by supplying spray water to the generated steam of the feed water heating boiler, the heating amount of the feed water supplied to the boiler can be reduced and adjusted. Thereby, even if it is a case where the property of the fuel thrown into a boiler for feed water heating changes, the heating amount of the feed water heated by the boiler for feed water heating can be adjusted to a desired value.
　さらに、本発明の一態様にかかる発電プラントでは、前記蒸気タービンから抽気した蒸気によって前記給水を加熱する給水加熱器を備え、前記制御部は、前記給水加熱用ボイラで発生した蒸気の一部を排出する蒸気制御弁、及び／又は、前記給水加熱用ボイラで発生した蒸気に対してスプレイ水を供給するスプレイ水供給手段を制御する制御と、前記給水熱用ボイラによって加熱された給水温度に応じて、前記給水加熱器に供給される蒸気の抽気量を制御する制御とを比較し、前記給水加熱用熱交換器で加熱された前記給水の温度が低い方の制御を選択する。 Furthermore, in the power plant according to one aspect of the present invention, the power plant includes a feed water heater that heats the feed water with steam extracted from the steam turbine, and the control unit removes a part of the steam generated in the feed water heating boiler. Depending on the steam control valve to discharge and / or control for controlling spray water supply means for supplying spray water to steam generated in the feed water heating boiler, and the feed water temperature heated by the feed water heat boiler Then, the control for controlling the extraction amount of steam supplied to the feed water heater is compared, and the control with the lower temperature of the feed water heated by the feed water heating heat exchanger is selected.
　さらに、本発明の一態様にかかる発電プラントでは、前記制御部は、前記蒸気タービンのタービン翼の強度に基づいて、前記蒸気の抽気量を制御する。 Furthermore, in the power plant according to one aspect of the present invention, the control unit controls the amount of steam extracted based on the strength of the turbine blades of the steam turbine.
　さらに、本発明の一態様にかかる発電プラントでは、前記過熱器から供給される過熱蒸気の温度を制御する過熱器スプレイを備え、前記制御部は、前記加熱量の変化量に基づいて前記過熱器スプレイのスプレイ量を制御する。 Furthermore, in the power plant according to one aspect of the present invention, the power plant includes a superheater spray that controls a temperature of superheated steam supplied from the superheater, and the control unit is configured to control the superheater based on a change amount of the heating amount. Controls the spray amount of the spray.
　さらに、本発明の一態様にかかる発電プラントでは、前記蒸気タービンから蒸気を抽気して前記給水を加熱する給水加熱器を備え、前記制御部は、前記給水熱用ボイラによって加熱された給水温度に応じて、前記給水加熱器に供給される蒸気の抽気量を制御する。 Furthermore, the power plant according to one aspect of the present invention includes a feed water heater that extracts steam from the steam turbine and heats the feed water, and the control unit has a feed water temperature heated by the feed water heat boiler. In response, the extraction amount of steam supplied to the feed water heater is controlled.
　蒸気タービンから抽気される蒸気量を調整することによって給水加熱器における加熱量を制御し、ボイラへ供給される給水温度を制御する。そして、給水加熱用ボイラによって加熱された給水温度に基づいて蒸気の抽気量を制御することとしたので、ボイラに供給される給水温度を所望値に制御することができる。 The amount of steam in the feed water heater is controlled by adjusting the amount of steam extracted from the steam turbine, and the temperature of the feed water supplied to the boiler is controlled. Since the steam extraction amount is controlled based on the feed water temperature heated by the feed water heating boiler, the feed water temperature supplied to the boiler can be controlled to a desired value.
　さらに、本発明の一態様にかかる発電プラントでは、前記制御部は、前記エコノマイザの出口水温度が飽和温度未満でかつ該飽和温度に近い温度となるように前記加熱量を制御する。 Furthermore, in the power plant according to one aspect of the present invention, the control unit controls the heating amount so that the outlet water temperature of the economizer is less than the saturation temperature and close to the saturation temperature.
　エコノマイザの出口水温度が、蒸気化しない飽和温度未満でかつ飽和温度に近い温度となるように給水加熱用ボイラの加熱量を制御することとしたので、給水を可能な限り加熱することができる。ここで、飽和温度未満でかつ飽和温度に近い温度とは、飽和温度よりも数℃（例えば２℃）から１０℃程度低い温度である。これにより、給水のエンタルピをエコノマイザの出口水温度が蒸気化しないよう可能な限り増大させて、タービン効率を向上して発電効率を向上させることができ、ボイラに投入する化石燃料を削減することができ、カーボンニュートラルとならない二酸化炭素の発生量を削減することができる。 Since the heating amount of the feed water heating boiler is controlled so that the outlet water temperature of the economizer is less than the saturation temperature that does not vaporize and close to the saturation temperature, the feed water can be heated as much as possible. Here, the temperature that is lower than the saturation temperature and close to the saturation temperature is a temperature that is lower than the saturation temperature by several degrees C (for example, 2 degrees C) to about 10 degrees C. As a result, the enthalpy of water supply can be increased as much as possible so that the economizer outlet water temperature does not vaporize, turbine efficiency can be improved and power generation efficiency can be improved, and fossil fuel input to the boiler can be reduced. The amount of carbon dioxide that does not become carbon neutral can be reduced.
　さらに、本発明の一態様にかかる発電プラントでは、前記ボイラから排出される排ガスを処理する排ガス処理装置を備え、前記制御部は、前記排ガス処理装置に供給される排ガスの上限温度未満でかつ該上限温度に近い温度となるように前記加熱量を制御する。 Furthermore, the power plant according to one aspect of the present invention includes an exhaust gas treatment device that treats the exhaust gas discharged from the boiler, and the control unit is less than an upper limit temperature of the exhaust gas supplied to the exhaust gas treatment device and The heating amount is controlled so that the temperature is close to the upper limit temperature.
　脱硝装置等の排ガス処理装置には、供給される排ガスの上限温度が規定されている。この上限温度未満でかつ上限温度に近い排ガス温度となるように給水加熱用ボイラの加熱量を増加させるよう制御することができる。ここで、上限温度未満でかつ上限温度に近い排ガス温度とは、例えば脱硝装置の触媒温度など排ガス流れ下流側に設置した機器の運転温度の上限温度よりも数℃（例えば２℃）から数１０℃程度低い温度である。排ガスの上限温度未満としたので、給水を可能な限り加熱することができる。これにより、給水のエンタルピを増大させて、タービン効率を向上して発電効率を向上させることができる。 In exhaust gas treatment devices such as a denitration device, an upper limit temperature of exhaust gas to be supplied is defined. It is possible to control to increase the heating amount of the feed water heating boiler so that the exhaust gas temperature is lower than the upper limit temperature and close to the upper limit temperature. Here, the exhaust gas temperature that is lower than the upper limit temperature and close to the upper limit temperature is, for example, several degrees Celsius (for example, 2 degrees Celsius) to several tens of degrees from the upper limit temperature of the operating temperature of the equipment installed downstream of the exhaust gas flow, such as the catalyst temperature of the denitration device. The temperature is lower by about ℃. Since the temperature is lower than the upper limit temperature of the exhaust gas, the water supply can be heated as much as possible. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved.
　さらに、本発明の一態様にかかる発電プラントでは、前記給水加熱用ボイラは、バイオマス燃料を主燃料として用いるバイオマスボイラとされている。 Furthermore, in the power plant according to one aspect of the present invention, the feed water heating boiler is a biomass boiler that uses biomass fuel as the main fuel.
　また、本発明の一態様にかかる発電プラントの運転方法は、エコノマイザ及び過熱器を有するボイラと、該ボイラにて生成された蒸気によって駆動される蒸気タービンと、該蒸気タービンによって駆動される発電機と、前記ボイラに供給される給水を加熱する給水加熱用ボイラと、前記給水加熱用ボイラで発生した加熱流体と前記ボイラへ供給される前記給水とを熱交換する給水加熱用熱交換器と、を備えた発電プラントの運転方法であって、前記給水加熱用ボイラが前記給水を加熱する加熱量を制御する。 A power plant operating method according to an aspect of the present invention includes a boiler having an economizer and a superheater, a steam turbine driven by steam generated in the boiler, and a generator driven by the steam turbine. A feed water heating boiler that heats the feed water supplied to the boiler, a feed water heating heat exchanger that exchanges heat between the heating fluid generated in the feed water heating boiler and the feed water supplied to the boiler, The feed water heating boiler controls the amount of heating by which the feed water is heated.
　給水加熱用ボイラの加熱量を制御することとしたので、ボイラの運転性能に影響を及ぼすことを抑制して給水を加熱することができる。
　また、給水加熱用ボイラをバイオマスボイラとすることで、ボイラにてバイオマス燃料を混焼させずに給水加熱用ボイラでバイオマス燃料を専焼させることとしたので、バイオマス燃料の使用比率を高めることができる。 Since the heating amount of the feed water heating boiler is controlled, the feed water can be heated while suppressing the influence on the operation performance of the boiler.
In addition, by using a biomass water boiler as the feed water heating boiler, the biomass fuel is exclusively fired in the feed water heating boiler without co-firing the biomass fuel in the boiler, so the use ratio of the biomass fuel can be increased.
本発明の一実施形態に係る発電プラントを示した概略構成図である。It is a schematic structure figure showing a power plant concerning one embodiment of the present invention. 過熱器スプレイによる温度変化を示した図である。It is the figure which showed the temperature change by a superheater spray. 高圧抽気弁の開度を示した図である。It is the figure which showed the opening degree of the high pressure extraction valve. バイオマスボイラ流体熱量計算を示したフローチャートである。It is the flowchart which showed the biomass boiler fluid calorie | heat amount calculation. 蒸気制御弁の開度制御を示した制御ブロック図である。It is the control block diagram which showed the opening degree control of the steam control valve. 高圧抽気弁の開度制御を示した制御ブロック図である。It is the control block diagram which showed the opening degree control of the high pressure extraction valve. バイオマスボイラの起動制御を示したフローチャートである。It is the flowchart which showed the starting control of the biomass boiler. バイオマスボイラの切離制御を示したフローチャートである。It is the flowchart which showed the separation control of the biomass boiler. バイオマスボイラを適用する前後での加熱量を示したグラフである。It is the graph which showed the amount of heating before and after applying a biomass boiler. バイオマスボイラを適用する前後での化石燃料エネルギに対する発電効率を示したグラフである。It is the graph which showed the power generation efficiency with respect to the fossil fuel energy before and after applying a biomass boiler. バイオマスボイラを適用する前のエネルギの内訳を示したグラフである。It is the graph which showed the breakdown of the energy before applying a biomass boiler. バイオマスボイラを適用した後のエネルギの内訳を示したグラフである。It is the graph which showed the breakdown of the energy after applying a biomass boiler. バイオマスボイラの加熱量の制御を用いない場合の効果を示したグラフである。It is the graph which showed the effect in the case of not using control of the heating amount of a biomass boiler. バイオマスボイラの加熱量の制御を用いた場合の効果を示したグラフである。It is the graph which showed the effect at the time of using control of the amount of heating of a biomass boiler. 蒸気制御弁及び高圧抽気弁の開度制御の変形例を示した制御ブロックズである。It is the control block which showed the modification of the opening degree control of a steam control valve and a high pressure extraction valve.
　以下に、本発明にかかる一実施形態について、図面を参照して説明する。
　図１には、一実施形態に係る発電プラント１が示されている。発電プラント１は、ボイラ３と、蒸気タービン５と、バイオマスボイラ（給水加熱用ボイラ）７とを備えている。 Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
FIG. 1 shows a power plant 1 according to an embodiment. The power plant 1 includes a boiler 3, a steam turbine 5, and a biomass boiler (feed water heating boiler) 7.
　ボイラ３は、ボイラ本体３ａの火炉１０内に石炭や石油等の化石燃料を用いて火炎を形成するバーナ１１を備えている。火炉１０を形成する炉壁は伝熱管とフィンによって構成された水冷壁１２とされており、水冷壁１２で加熱された水は蒸気ドラム１５へと導かれる。水冷壁１２の鉛直下方側には水ドラム１４が設けられている。水ドラム１４へは、循環ポンプ２０によって蒸気ドラム１５内の水が導かれるとともに、水冷壁１２へ水を供給するようになっている。なお、本実施形態では、ドラムを有する亜臨界圧ボイラを例としているが、ドラムを有さない超臨界圧ボイラにも適用することができる。 The boiler 3 includes a burner 11 that forms a flame using fossil fuel such as coal or oil in the furnace 10 of the boiler body 3a. The furnace wall forming the furnace 10 is a water-cooled wall 12 composed of heat transfer tubes and fins, and water heated by the water-cooled wall 12 is guided to a steam drum 15. A water drum 14 is provided on the vertically lower side of the water cooling wall 12. Water in the steam drum 15 is guided to the water drum 14 by the circulation pump 20 and water is supplied to the water cooling wall 12. In this embodiment, a subcritical pressure boiler having a drum is taken as an example, but the present invention can also be applied to a supercritical pressure boiler having no drum.
　バーナ１１の火炎によって発生する燃焼排ガスは、火炉１０の鉛直上方側へと流れ、過熱器１３へと導かれる。過熱器１３の燃焼排ガス流れ下流側には、再熱器１７とエコノマイザ１８とがこの順番で設けられている。 The combustion exhaust gas generated by the flame of the burner 11 flows vertically upward of the furnace 10 and is guided to the superheater 13. A reheater 17 and an economizer 18 are provided in this order on the downstream side of the combustion exhaust gas flow of the superheater 13.
　エコノマイザ１８と蒸気ドラム１５との間には、エコノマイザ１８にて加熱された後の水が流通するエコノマイザ出口配管２２が接続されている。エコノマイザ出口配管２２には、エコノマイザ出口温度センサ２２Ｔと、エコノマイザ出口圧力センサ２２Ｐとが設けられている。これらセンサ２２Ｔ，２２Ｐの計測値は、制御部３０へ送られるようになっている。 Between the economizer 18 and the steam drum 15, an economizer outlet pipe 22 through which water after being heated by the economizer 18 circulates is connected. The economizer outlet pipe 22 is provided with an economizer outlet temperature sensor 22T and an economizer outlet pressure sensor 22P. The measured values of these sensors 22T and 22P are sent to the control unit 30.
　エコノマイザ１８には、給水（水）を供給するための給水配管２４が接続されている。給水配管２４を通る給水は、後述するように、バイオマスボイラ７で発生した蒸気によって加熱された後にエコノマイザ１８へと供給される。エコノマイザ１８の入口側の給水配管２４には、温度センサ５８Ｔが設けられている。この温度センサ５８Ｔの計測値は、制御部３０へと送られる。 A water supply pipe 24 for supplying water (water) is connected to the economizer 18. As will be described later, the feed water passing through the feed water pipe 24 is heated by steam generated in the biomass boiler 7 and then supplied to the economizer 18. A temperature sensor 58T is provided in the water supply pipe 24 on the inlet side of the economizer 18. The measured value of the temperature sensor 58T is sent to the control unit 30.
　エコノマイザ１８を通過した燃焼排ガス流れ下流側には、エコノマイザ１８を通過した後の燃焼排ガスの温度を計測する燃焼排ガス温度センサ２５Ｔが設けられている。燃焼排ガス温度センサ２５Ｔの計測値は、制御部３０へと送られる。燃焼排ガス温度センサ２５Ｔを通過した後の燃焼排ガスは、ボイラ本体３ａに接続された排ガスダクトの途中位置に燃焼ガス中のＮＯｘを除去するために設けられた脱硝装置（図示せず）へと導かれる。 A combustion exhaust gas temperature sensor 25T that measures the temperature of the combustion exhaust gas after passing through the economizer 18 is provided on the downstream side of the combustion exhaust gas flow that has passed through the economizer 18. The measured value of the combustion exhaust gas temperature sensor 25T is sent to the control unit 30. The combustion exhaust gas after passing through the combustion exhaust gas temperature sensor 25T is led to a denitration device (not shown) provided for removing NOx in the combustion gas at a midway position of the exhaust gas duct connected to the boiler body 3a. It is burned.
　脱硝装置は、アンモニアを用いた選択触媒還元脱硝装置とされており、触媒反応温度の関係で上限温度（例えば４００℃～４２０℃程度）が定められている。したがって、燃焼排ガス温度センサ２５Ｔの温度に基づいて、例えば、脱硝装置の上限温度を超えないように制御部３０によってボイラ３内の熱交換量を調整して燃焼排ガス温度が制御される。脱硝装置を通過した燃焼排ガスは、例えば、燃焼ガス中のＳＯｘを除去するために脱硫装置（図示せず）にてＳＯｘ等を除去された後に、更に下流側では図示しない煤塵処理装置、誘引送風機などが必要に応じて設けられており、排ガスダクトの下流端部の煙突から大気へと排出される。 The denitration device is a selective catalytic reduction denitration device using ammonia, and an upper limit temperature (for example, about 400 ° C. to 420 ° C.) is determined in relation to the catalytic reaction temperature. Therefore, based on the temperature of the combustion exhaust gas temperature sensor 25T, for example, the control unit 30 adjusts the amount of heat exchange in the boiler 3 so as not to exceed the upper limit temperature of the denitration device, thereby controlling the combustion exhaust gas temperature. The combustion exhaust gas that has passed through the denitration device is, for example, SOx etc. removed by a desulfurization device (not shown) in order to remove SOx in the combustion gas, and further, a dust treatment device and an induction blower not shown on the downstream side Etc. are provided as necessary, and discharged from the chimney at the downstream end of the exhaust gas duct to the atmosphere.
　過熱器１３には、過熱器スプレイ２７が設けられている。過熱器スプレイ２７から水や蒸気を噴射することで過熱器１３内を流れる過熱蒸気を素早く冷却して所定範囲の温度へと制御する。過熱器スプレイ２７で用いる水は、例えばエコノマイザ１８の出口水の一部が用いられる。過熱器スプレイ２７の水噴射量や噴射タイミングは、制御部３０によって制御される。 The superheater 13 is provided with a superheater spray 27. By injecting water or steam from the superheater spray 27, the superheated steam flowing in the superheater 13 is quickly cooled and controlled to a temperature within a predetermined range. For example, a part of the outlet water of the economizer 18 is used as the water used in the superheater spray 27. The water injection amount and the injection timing of the superheater spray 27 are controlled by the control unit 30.
　図１では過熱器スプレイ２７の設置位置が模式的に示されているが、より具体的な設置位置について図２を用いて説明する。図２に示されたものは、過熱器１３は、例えば１次過熱器１３ａと２次過熱器１３ｂと３次過熱器１３ｃとを備えている。過熱器スプレイ２７は、１次過熱器１３ａと２次過熱器１３ｂとの間と、２次過熱器１３ｂと３次過熱器１３ｃとの間とにそれぞれ設けられており、これらの位置で水を噴射して過熱蒸気温度を段階的に低下させる。すなわち、１次過熱器出口設定温度となるように１次過熱器１３ａの出口に水スプレイを行い、２次過熱器出口設定温度となるように２次過熱器１３ｂの出口に水スプレイを行う。このように水スプレイを行って蒸気温度を制御することにより、各過熱器出口設定温度が調整され、蒸気タービン５へ供給される主蒸気の温度が所定範囲の温度になるよう制御される。 FIG. 1 schematically shows the installation position of the superheater spray 27, but a more specific installation position will be described with reference to FIG. As shown in FIG. 2, the superheater 13 includes, for example, a primary superheater 13a, a secondary superheater 13b, and a tertiary superheater 13c. The superheater spray 27 is provided between the primary superheater 13a and the secondary superheater 13b, and between the secondary superheater 13b and the tertiary superheater 13c, respectively. Inject to reduce the superheated steam temperature step by step. That is, water spray is performed at the outlet of the primary superheater 13a so as to be the primary superheater outlet set temperature, and water spray is performed at the outlet of the secondary superheater 13b so as to be the secondary superheater outlet set temperature. By controlling the steam temperature by performing water spray in this way, each superheater outlet set temperature is adjusted, and the temperature of the main steam supplied to the steam turbine 5 is controlled to be within a predetermined range.
　また、図示しないが、再熱器１７に対しても再熱器スプレイが設けられていてもよい。再熱器スプレイの水噴射量や噴射タイミングについても、制御部３０によって制御される。 Although not shown, a reheater spray may be provided for the reheater 17 as well. The water injection amount and the injection timing of the reheater spray are also controlled by the control unit 30.
　過熱器１３を出た過熱蒸気は、図１に示すように、主蒸気配管３２を通り蒸気タービン５へと導かれる。蒸気タービン５は、本実施形態では、例えば、高圧タービン３４と中圧タービン３５と低圧タービン３６とを備えている。これらタービン３４，３５，３６にて発生した回転動力によって発電機３７が回転駆動され、発電が行われる。 The superheated steam exiting the superheater 13 is guided to the steam turbine 5 through the main steam pipe 32 as shown in FIG. In the present embodiment, the steam turbine 5 includes, for example, a high-pressure turbine 34, an intermediate-pressure turbine 35, and a low-pressure turbine 36. The generator 37 is rotationally driven by the rotational power generated in the turbines 34, 35, and 36, and power is generated.
　主蒸気配管３２は、高圧タービン３４の入口に接続されている。高圧タービン３４の排気側には、高圧タービン出口配管３８が接続されている。高圧タービン出口配管３８の下流端は再熱器１７に接続されており、高圧タービン３４で所定の膨張を行ってタービンを回転駆動させる仕事を終えた蒸気が再熱器１７へと導かれるようになっている。 The main steam pipe 32 is connected to the inlet of the high-pressure turbine 34. A high pressure turbine outlet pipe 38 is connected to the exhaust side of the high pressure turbine 34. The downstream end of the high-pressure turbine outlet pipe 38 is connected to the reheater 17 so that steam that has been subjected to predetermined expansion by the high-pressure turbine 34 and rotationally driven the turbine is guided to the reheater 17. It has become.
　再熱器１７の蒸気出口側と中圧タービン３５との間には、再熱蒸気を中圧タービン３５に供給する再熱蒸気供給配管４０が設けられている。 A reheat steam supply pipe 40 for supplying reheat steam to the intermediate pressure turbine 35 is provided between the steam outlet side of the reheater 17 and the intermediate pressure turbine 35.
　中圧タービン３５の排気側には、中圧タービン出口配管４２が接続されている。中圧タービン出口配管４２の下流端は低圧タービン３６の入口に接続されており、中圧タービン３５で所定の膨張を行ってタービンを回転駆動させる仕事を終えた蒸気が低圧タービン３６へと導かれるようになっている。 The intermediate pressure turbine outlet pipe 42 is connected to the exhaust side of the intermediate pressure turbine 35. The downstream end of the intermediate-pressure turbine outlet pipe 42 is connected to the inlet of the low-pressure turbine 36, and steam that has been subjected to predetermined expansion in the intermediate-pressure turbine 35 and rotationally driven the turbine is guided to the low-pressure turbine 36. It is like that.
　低圧タービン３６の排気側には、低圧タービン出口配管４４が接続されている。低圧タービン出口配管４４の下流端は復水器４６に接続されている。復水器４６では、図示しない冷却水によって蒸気が真空下へと冷却され凝縮液化する。復水器４６にて液化した復水は給水となって、復水ポンプ４８によって低圧給水加熱器５０へと導かれる。 A low-pressure turbine outlet pipe 44 is connected to the exhaust side of the low-pressure turbine 36. The downstream end of the low-pressure turbine outlet pipe 44 is connected to a condenser 46. In the condenser 46, the steam is cooled to a vacuum by a cooling water (not shown) and is condensed and liquefied. The condensate liquefied by the condenser 46 becomes feed water and is led to the low-pressure feed water heater 50 by the condensate pump 48.
　本実施形態では、例えば、低圧給水加熱器５０では、低圧タービン３６から導かれた低圧蒸気によって復水からの給水が加熱される。低圧給水加熱器５０にて加熱された給水は、給水ポンプ５１を通り第１中圧給水加熱器５２ａ及び第２中圧給水加熱器５２ｂへ導かれて、中圧タービン３５から抽気された中圧蒸気によって加熱される。各中圧給水加熱器５２ａ，５２ｂによって加熱された給水は、第１高圧給水加熱器５４ａ及び第２高圧給水加熱器５４ｂへと導かれる。 In the present embodiment, for example, in the low-pressure feed water heater 50, the feed water from the condensate is heated by the low-pressure steam guided from the low-pressure turbine 36. The feed water heated by the low pressure feed water heater 50 is guided to the first intermediate pressure feed water heater 52a and the second intermediate pressure feed water heater 52b through the feed pump 51, and is extracted from the intermediate pressure turbine 35. Heated by steam. The feed water heated by each of the medium pressure feed water heaters 52a and 52b is guided to the first high pressure feed water heater 54a and the second high pressure feed water heater 54b.
　第１高圧給水加熱器５４ａに導かれる高圧蒸気は、第１高圧抽気配管５５ａを介して導かれる。第１高圧抽気配管５５ａには、制御部３０によって開度が制御される第１高圧抽気弁５６ａが設けられている。
　第２高圧給水加熱器５４ｂに導かれる高圧蒸気は、第２高圧抽気配管５５ｂを介して導かれる。第２高圧抽気配管５５ｂには、制御部３０によって開度が制御される第２高圧抽気弁５６ｂが設けられている。
　なお、本実施形態では、一例として第１高圧抽気配管５５ａは、第２高圧抽気配管５５ｂよりも高圧タービン３４の上流側（高圧側）に接続されているので、第１高圧抽気配管５５ａによって導かれる高圧蒸気の圧力は、第２高圧抽気配管５５ｂによって導かれる高圧蒸気の圧力よりも高くされている。 The high-pressure steam guided to the first high-pressure feed water heater 54a is guided via the first high-pressure extraction pipe 55a. The first high pressure extraction pipe 55a is provided with a first high pressure extraction valve 56a whose opening degree is controlled by the control unit 30.
The high-pressure steam guided to the second high-pressure feed water heater 54b is guided via the second high-pressure extraction pipe 55b. The second high pressure extraction pipe 55b is provided with a second high pressure extraction valve 56b whose opening degree is controlled by the control unit 30.
In the present embodiment, as an example, the first high-pressure extraction pipe 55a is connected to the upstream side (high-pressure side) of the high-pressure turbine 34 relative to the second high-pressure extraction pipe 55b. The pressure of the high-pressure steam to be applied is higher than the pressure of the high-pressure steam guided by the second high-pressure extraction pipe 55b.
　図３には、本実施形態の一例としてボイラ３の負荷に対する各高圧抽気弁５６ａ，５６ｂの開度が示されている。図３に示されたマップ（ロードプログラム）は、制御部３０の記憶部に格納されていて、負荷に応じて事前に設定された弁開度とする。同図に示すように、ボイラ３の負荷が１００％となる場合には、両高圧抽気弁５６ａ，５６ｂが全閉となる。負荷が所定値よりも小さくなる場合には、両高圧抽気弁５６ａ，５６ｂが全開となる。ただし、本実施形態では、全閉と全開とを切り替える負荷域を第１高圧抽気弁５６ａと第２高圧抽気弁５６ｂとで異なるように設定することで、給水の加熱の制御性を向上している。具体的には、第１高圧抽気弁５６ａの方が第２高圧抽気弁５６ｂよりも高負荷側で動作するようになっている。これにより、高圧蒸気の抽気流量を第１高圧抽気弁５６ａで変更し、その不足分を第２高圧抽気弁５６ｂで変更することで、広い範囲で任意に制御することができる。なお、後述するように、バイオマスボイラ７を投入する場合には、図３に示したマップに代えて、ボイラ３の負荷に関わらず高圧抽気弁５６ａ，５６ｂが閉じる方向に制御される。 FIG. 3 shows the opening degrees of the high- pressure bleed valves 56a and 56b with respect to the load of the boiler 3 as an example of the present embodiment. The map (load program) shown in FIG. 3 is stored in the storage unit of the control unit 30, and the valve opening is set in advance according to the load. As shown in the figure, when the load on the boiler 3 is 100%, both the high- pressure extraction valves 56a and 56b are fully closed. When the load is smaller than a predetermined value, both the high pressure bleed valves 56a and 56b are fully opened. However, in this embodiment, the load area for switching between fully closed and fully opened is set to be different between the first high pressure bleed valve 56a and the second high pressure bleed valve 56b, thereby improving the controllability of heating of the feed water. Yes. Specifically, the first high pressure bleed valve 56a operates on the higher load side than the second high pressure bleed valve 56b. As a result, by changing the extraction flow rate of the high-pressure steam with the first high-pressure extraction valve 56a and changing the shortage with the second high-pressure extraction valve 56b, it is possible to arbitrarily control in a wide range. As will be described later, when the biomass boiler 7 is charged, the high pressure extraction valves 56a and 56b are controlled in the closing direction regardless of the load of the boiler 3 instead of the map shown in FIG.
　各給水加熱器５０，５２ａ，５２ｂ，５４ａ，５４ｂにて給水を加熱した後の蒸気は、図１にて破線矢印で示すように、順次低圧段の給水加熱器５０，５２ａ，５２ｂ，５４ａ，５４ｂへと送られ、最終的には復水器４６にて回収される。 The steam after the feed water is heated by each feed water heater 50, 52a, 52b, 54a, 54b is sequentially supplied to the low pressure stage feed water heaters 50, 52a, 52b, 54a, as indicated by broken line arrows in FIG. 54b and finally collected by the condenser 46.
　高圧給水加熱器５４ａ，５４ｂにて加熱された後の給水は、給水配管２４を通り、給水加熱用熱交換器６０へと導かれる。給水加熱用熱交換器６０では、バイオマスボイラ７から加熱用伝熱管６１に導かれた蒸気によって給水が加熱されるようになっている。バイオマスボイラ７と給水加熱用熱交換器６０との間には、加熱用伝熱管６１へ蒸気を供給する加熱用蒸気供給配管６２と、加熱用伝熱管６１を通過し熱交換した後にドレン化したドレン水をバイオマスボイラ７へと返送する返送配管６４と返送ポンプ６５が設けられている。 The feed water after being heated by the high-pressure feed water heaters 54a and 54b is guided to the feed water heating heat exchanger 60 through the feed water pipe 24. In the feed water heating heat exchanger 60, the feed water is heated by the steam guided from the biomass boiler 7 to the heating heat transfer tube 61. Between the biomass boiler 7 and the feed water heating heat exchanger 60, the steam is supplied to the heating heat transfer pipe 61, and the heating steam supply pipe 62 is passed through the heating heat transfer pipe 61 to perform drainage. A return pipe 64 and a return pump 65 for returning the drain water to the biomass boiler 7 are provided.
　加熱用蒸気供給配管６２には、加熱用蒸気の温度を計測する加熱用蒸気温度センサ６２Ｔと、加熱用蒸気の圧力を計測する加熱用蒸気圧力センサ６２Ｐと、加熱用蒸気の流量を計測する加熱用蒸気流量センサ６２Ｆとが設けられている。各センサ６２Ｔ，６２Ｐ，６２Ｆの計測値は、制御部３０へと送られる。制御部３０では、バイオマスボイラ７で発生した蒸気（加熱流体）の熱量であり給水加熱用熱交換器６０に出力する熱量となるバイオマスボイラ流体熱量が計算されるようになっている。具体的には、図４に示すように、バイオマスボイラ７の発生蒸気の熱量計算が開始されると（ステップＳ００）、各センサ６２Ｔ，６２Ｐ，６２Ｆから発生蒸気の温度、圧力及び流量を得る（ステップＳ０１）。次に、得られた温度及び圧力から、蒸気表にしたがって発生蒸気のエンタルピを算出する（ステップＳ０２）。なお、蒸気表は、制御部３０の記憶部に格納されている。そして、エンタルピと得られた流量とを乗算することによって発生蒸気の熱量を得て（ステップＳ０３）、バイオマスボイラ流体熱量の計算を終了する（ステップＳ０４）。このように得られたバイオマスボイラ流体熱量は、後述する蒸気制御弁７２の制御に用いられる。 The heating steam supply pipe 62 includes a heating steam temperature sensor 62T that measures the temperature of the heating steam, a heating steam pressure sensor 62P that measures the pressure of the heating steam, and a heating that measures the flow rate of the heating steam. A steam flow rate sensor 62F is provided. The measured values of the sensors 62T, 62P, and 62F are sent to the control unit 30. In the control unit 30, a biomass boiler fluid calorific value which is a calorific value of steam (heating fluid) generated in the biomass boiler 7 and which is a calorific value output to the feed water heating heat exchanger 60 is calculated. Specifically, as shown in FIG. 4, when the calorie calculation of the generated steam of the biomass boiler 7 is started (step S00), the temperature, pressure and flow rate of the generated steam are obtained from the sensors 62T, 62P, 62F ( Step S01). Next, the enthalpy of the generated steam is calculated from the obtained temperature and pressure according to the steam table (step S02). The steam table is stored in the storage unit of the control unit 30. Then, the calorific value of the generated steam is obtained by multiplying the enthalpy by the obtained flow rate (step S03), and the calculation of the biomass boiler fluid calorific value is terminated (step S04). The biomass boiler fluid calorie obtained in this way is used to control a steam control valve 72 described later.
　返送配管６４の途中には、返送ポンプ６５が設けられており、返送ポンプ６５によってドレン水がバイオマスボイラ７へと送られ、バイオマスボイラ７と給水加熱用熱交換器６０との間で循環するようになっている。 A return pump 65 is provided in the middle of the return pipe 64 so that drain water is sent to the biomass boiler 7 by the return pump 65 and circulates between the biomass boiler 7 and the heat exchanger 60 for heating the feed water. It has become.
　給水加熱用熱交換器６０をバイパスするように、給水バイパス配管６７が設けられている。給水バイパス配管６７には、制御部３０によって開閉が制御される給水バイパス弁６８が設けられている。給水バイパス弁６８は、給水加熱用熱交換器６０を利用する場合は全閉とされ、給水加熱用熱交換器６０を利用しない場合は全開とされる。給水バイパス配管６７の上流側の給水配管２４には、給水加熱用熱交換器入口温度を計測する温度センサ５７Ｔが設けられている。この温度センサ５７Ｔの計測値は、制御部３０へと送られる。 A feed water bypass pipe 67 is provided so as to bypass the feed water heating heat exchanger 60. The water supply bypass pipe 67 is provided with a water supply bypass valve 68 whose opening and closing is controlled by the control unit 30. The feed water bypass valve 68 is fully closed when the feed water heating heat exchanger 60 is used, and is fully opened when the feed water heating heat exchanger 60 is not used. A temperature sensor 57 </ b> T for measuring a feed water heating heat exchanger inlet temperature is provided in the feed water pipe 24 on the upstream side of the feed water bypass pipe 67. The measured value of the temperature sensor 57T is sent to the control unit 30.
　バイオマスボイラ７は、バイオマス燃料を燃焼させて蒸気を発生する。バイオマスボイラ７の出力は、制御部３０によって制御される。具体的には、バイオマスボイラ７に投入するバイオマス燃料の供給量、燃焼用空気の流量、発生した蒸気の供給量等が制御部３０によって制御される。 The biomass boiler 7 generates steam by burning biomass fuel. The output of the biomass boiler 7 is controlled by the control unit 30. Specifically, the supply amount of biomass fuel input to the biomass boiler 7, the flow rate of combustion air, the supply amount of generated steam, and the like are controlled by the control unit 30.
　バイオマスボイラ７には、制御部３０によって開度制御される蒸気制御弁７２が設けられている。蒸気制御弁７２を介してバイオマスボイラ７の発生蒸気の一部が復水器４６へと排出される。ただし、蒸気の排出先は、復水器４６に限定されるものではなく、例えば別の冷却装置や大気放出でもよい。また、加熱用蒸気供給配管６２に、加熱蒸気用スプレイ（スプレイ水供給手段）７３を設けても良い。加熱蒸気用スプレイ７３から水を加熱用蒸気供給配管６２内に噴射することで、蒸気温度を低下させる。加熱蒸気用スプレイ７３の起動及び停止は、制御部３０によって制御される。 The biomass boiler 7 is provided with a steam control valve 72 whose opening degree is controlled by the control unit 30. Part of the steam generated by the biomass boiler 7 is discharged to the condenser 46 via the steam control valve 72. However, the discharge destination of the steam is not limited to the condenser 46, and may be another cooling device or atmospheric discharge, for example. Further, the heating steam supply pipe 62 may be provided with a heating steam spray (spray water supply means) 73. By injecting water into the heating steam supply pipe 62 from the heating steam spray 73, the steam temperature is lowered. The starting and stopping of the heating steam spray 73 is controlled by the control unit 30.
　バイオマスボイラ７を循環する蒸気やドレン水が蒸気制御弁７２より排出された場合など、循環する給水量が不足した場合は、返送配管６４の返送ポンプ６５より上流側へ図示しない給水ラインにより、復水器４６の復水の一部を給水しても良い。 When the amount of water to be circulated is insufficient, such as when steam or drain water circulating through the biomass boiler 7 is discharged from the steam control valve 72, the water is returned to the upstream side of the return pump 65 of the return pipe 64 by a water supply line (not shown). A part of the condensate of the water device 46 may be supplied.
　制御部３０は、例えば、ＣＰＵ（Central　Processing　Unit）、ＲＡＭ（Random　Access　Memory）、ＲＯＭ（Read　Only　Memory）、及びコンピュータ読み取り可能な記憶媒体等から構成されている。そして、各種機能を実現するための一連の処理は、一例として、プログラムの形式で記憶媒体等に記憶されており、このプログラムをＣＰＵがＲＡＭ等に読み出して、情報の加工・演算処理を実行することにより、各種機能が実現される。なお、プログラムは、ＲＯＭやその他の記憶媒体に予めインストールしておく形態や、コンピュータ読み取り可能な記憶媒体に記憶された状態で提供される形態、有線又は無線による通信手段を介して配信される形態等が適用されてもよい。コンピュータ読み取り可能な記憶媒体とは、磁気ディスク、光磁気ディスク、ＣＤ－ＲＯＭ、ＤＶＤ－ＲＯＭ、半導体メモリ等である。 The control unit 30 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is preinstalled in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.
　上記構成の発電プラント１は、以下のように動作する。
　ボイラ３の過熱器１３にて生成された過熱蒸気は、蒸気タービン５の高圧タービン３４へと導かれ、高圧タービン３４を回転駆動させた後に、再熱器１７へと導かれる。再熱器１７へと導かれた蒸気はボイラ３によって再加熱され、再熱蒸気として中圧タービン３５へと導かれる。再熱蒸気は、中圧タービン３５を回転駆動させた後に、低圧タービン３６へと導かれて低圧タービン３６を回転駆動させる。このように得た回転動力によって発電機３７が回転駆動され、発電が行われる。 The power plant 1 having the above-described configuration operates as follows.
The superheated steam generated in the superheater 13 of the boiler 3 is guided to the high-pressure turbine 34 of the steam turbine 5, and after being driven to rotate, is guided to the reheater 17. The steam guided to the reheater 17 is reheated by the boiler 3 and guided to the intermediate pressure turbine 35 as reheated steam. The reheat steam rotates the intermediate pressure turbine 35 and then guides it to the low pressure turbine 36 to rotate the low pressure turbine 36. The generator 37 is rotationally driven by the rotational power thus obtained, and power generation is performed.
　低圧タービン３６にて所定の膨張を行ってタービンを回転駆動させる仕事を終えた蒸気は復水器４６にて復水となり、給水として各給水加熱器５０，５２ｂ，５２ａ，５４ｂ，５４ａを順次通過することによって加熱される。その後、給水は、給水加熱用熱交換器６０によってさらに加熱され、ボイラ３のエコノマイザ１８に供給される。 The steam that has been subjected to predetermined expansion in the low-pressure turbine 36 and rotationally driven the turbine becomes condensate in the condenser 46, and sequentially passes through each of the feed water heaters 50, 52b, 52a, 54b, 54a as feed water. To be heated. Thereafter, the feed water is further heated by the feed water heating heat exchanger 60 and supplied to the economizer 18 of the boiler 3.
　給水加熱用熱交換器６０における給水の加熱量は、バイオマスボイラ７の出力を制御部３０によって制御することで調整される。具体的には以下の通りである。 The heating amount of the feed water in the feed water heating heat exchanger 60 is adjusted by controlling the output of the biomass boiler 7 by the control unit 30. Specifically, it is as follows.
＜エコノマイザ出口温度に基づく制御＞
　エコノマイザ１８で加熱した後の水の出口温度が飽和温度を超えて蒸気化しないように制御する。これにより、エコノマイザ１８出口の水が蒸気となるのを防止しつつ、可能な限り高い給水温度を実現する。
　制御部３０は、エコノマイザ出口用圧力センサ２２Ｐの計測圧力、温度センサ２２Ｔの計測温度から飽和温度Ｔ１を得る。そして、この飽和温度Ｔ１を所定値（例えば２℃～１０℃）の範囲で下回る飽和温度に近い温度をエコノマイザ出口温度設定値Ｔ１ｓｅｔとし、このエコノマイザ出口温度設定値Ｔ１ｓｅｔとなるように、制御部３０はバイオマスボイラ７の出力をフィードバック制御する。これにより、エコノマイザ１８の出口水温度が蒸気化しないよう、給水の温度を可能な限り高くして、給水のエンタルピを可能な限り増大させる。 <Control based on economizer outlet temperature>
Control is performed so that the outlet temperature of the water heated by the economizer 18 does not evaporate beyond the saturation temperature. Thereby, the water supply temperature as high as possible is realized while preventing the water at the outlet of the economizer 18 from becoming steam.
The control unit 30 obtains the saturation temperature T1 from the measured pressure of the economizer outlet pressure sensor 22P and the measured temperature of the temperature sensor 22T. A temperature close to the saturation temperature below the saturation temperature T1 within a range of a predetermined value (for example, 2 ° C. to 10 ° C.) is set as an economizer outlet temperature setting value T1set, and the control unit 30 Feedback-controls the output of the biomass boiler 7. Thereby, the temperature of water supply is made as high as possible so that the outlet water temperature of the economizer 18 is not vaporized, and the enthalpy of water supply is increased as much as possible.
＜燃焼排ガス温度に基づく制御＞
　燃焼排ガス下流側に設置した機器の上限温度を考慮するにあたり、本実施形態では、脱硝装置の触媒反応温度から決まる上限温度Ｔ２を超えないように制御する。これにより、脱硝装置の触媒反応を維持しつつ、可能な限り高い給水温度を実現する。
　制御部３０は、燃焼排ガス温度センサ２５Ｔの計測温度を得て上限温度Ｔ２を所定値（例えば５℃～数１０℃（例えば５０℃））の範囲で下回る温度を燃焼排ガス温度設定値Ｔ２ｓｅｔとし、この燃焼排ガス温度設定値Ｔ２ｓｅｔとなるように、制御部３０はバイオマスボイラ７の出力をフィードバック制御する。これにより、エコノマイザ１８を通過した燃焼排ガスが上限温度を超えないように、給水の温度を可能な限り高くして、給水のエンタルピを可能な限り増大させる。 <Control based on combustion exhaust gas temperature>
In consideration of the upper limit temperature of the equipment installed on the downstream side of the combustion exhaust gas, in this embodiment, control is performed so as not to exceed the upper limit temperature T2 determined from the catalytic reaction temperature of the denitration apparatus. Thereby, the feed water temperature as high as possible is realized while maintaining the catalytic reaction of the denitration apparatus.
The control unit 30 obtains the temperature measured by the combustion exhaust gas temperature sensor 25T and sets the temperature below the upper limit temperature T2 within a predetermined value (for example, 5 ° C. to several tens of degrees Celsius (for example, 50 ° C.)) as the combustion exhaust gas temperature set value T2set. The control unit 30 feedback-controls the output of the biomass boiler 7 so that the combustion exhaust gas temperature set value T2set is obtained. Thereby, the temperature of the feed water is increased as much as possible so that the combustion exhaust gas that has passed through the economizer 18 does not exceed the upper limit temperature, and the enthalpy of the feed water is increased as much as possible.
＜バイオマスボイラの加熱量制御＞
　制御部３０は、上述のエコノマイザ出口温度に基づく制御と燃焼排ガス温度に基づく制御の両方を満たすようにバイオマスボイラ７からの加熱量（例えば、蒸気量・圧力・温度および出熱量）を制御する。
　図５には、蒸気制御弁７２を用いたバイオマスボイラ７の加熱量制御が示されている。具体的には、制御部３０において、バイオマスボイラ７から給水加熱用熱交換器６０に出力する熱量の設定値であるバイオマスボイラ流体熱量設定値と、図４を用いて説明した計算に従って得られたバイオマスボイラ流体熱量計算値との差分をとり、この差分量に応じて、先行制御またはフィードバック制御によって蒸気制御弁７２の開度を制御し、バイオマスボイラ７の発生蒸気のうち差分量にあたる給水加熱用熱交換器６０に供給しない蒸気を復水器４６へと供給する。バイオマスボイラ７の発生蒸気流量を制御することでバイオマスボイラ流体熱量が迅速に制御される。バイオマスボイラ流体熱量設定値は、発電プラント１全体のヒートバランスから予め計算しておき、制御部３０の記憶部に格納されている。また、バイオマスボイラ流体熱量計算値がバイオマスボイラ流体熱量設定値より少ない場合は、バイオマスボイラ７へのバイオマス燃料の供給量、燃焼用空気の流量などを増やして加熱量を増加するよう制御される。バイオマス燃料の発熱量変化が多いなど、バイオマスボイラ流体熱量計算値がバイオマスボイラ流体熱量設定値より少ない場合が頻繁に発生する場合は、バイオマスボイラ流体熱量計算値が若干多くなる頻度を増加するように、バイオマスボイラ７の出力に対する制御部３０の時定数を変更しても良い。
　なお、蒸気制御弁７２の制御に代えて、加熱蒸気用スプレイ７３の起動及び停止を行っても良い。加熱蒸気用スプレイ７３でバイオマスボイラ流体熱量を素早く制御できる。また、蒸気制御弁７２と加熱蒸気用スプレイ７３を併用しても良い。 <Heating amount control of biomass boiler>
The control unit 30 controls the heating amount (for example, steam amount, pressure, temperature, and heat output amount) from the biomass boiler 7 so as to satisfy both the control based on the economizer outlet temperature and the control based on the combustion exhaust gas temperature.
FIG. 5 shows the heating amount control of the biomass boiler 7 using the steam control valve 72. Specifically, in the control unit 30, the biomass boiler fluid calorific value set value, which is the calorific value set value output from the biomass boiler 7 to the feed water heating heat exchanger 60, and the calculation described with reference to FIG. 4 were obtained. Taking the difference from the calculated value of the biomass boiler fluid calorific value, the opening degree of the steam control valve 72 is controlled by advance control or feedback control according to this difference amount, and for feed water heating corresponding to the difference amount among the steam generated by the biomass boiler 7 Steam not supplied to the heat exchanger 60 is supplied to the condenser 46. By controlling the generated steam flow rate of the biomass boiler 7, the biomass boiler fluid heat quantity is quickly controlled. The biomass boiler fluid calorific value set value is calculated in advance from the heat balance of the entire power plant 1 and stored in the storage unit of the control unit 30. When the calculated value of the biomass boiler fluid calorific value is smaller than the set value of the biomass boiler fluid calorific value, the amount of heating is controlled to increase by increasing the amount of biomass fuel supplied to the biomass boiler 7, the flow rate of combustion air, and the like. If the calculated value of biomass boiler fluid calorie is less than the set value of biomass boiler fluid calorie, such as when there is a large change in the calorific value of biomass fuel, increase the frequency at which the calculated value of the biomass boiler fluid calorific value increases slightly. The time constant of the control unit 30 for the output of the biomass boiler 7 may be changed.
Instead of controlling the steam control valve 72, the heating steam spray 73 may be started and stopped. The biomass boiler fluid heat quantity can be quickly controlled by the heating steam spray 73. Further, the steam control valve 72 and the heating steam spray 73 may be used in combination.
＜高圧抽気弁の制御＞
　上述のようにバイオマスボイラ７の加熱量を制御しつつ、さらに高圧抽気弁５６ａ，５６ｂを制御して、高圧蒸気の抽気量の制御を行う。具体的には、制御部３０は、高圧抽気弁５６ａ，５６ｂの制御を以下のように行う。
　バイオマスボイラ７を投入していない場合、すなわち給水加熱用熱交換器６０によって給水を加熱していない場合は、図３に示したマップにあるロードプログラムに従い、ボイラ３の負荷に応じて高圧抽気弁５６ａ，５６ｂの開度を制御する。 <Control of high pressure bleed valve>
While controlling the heating amount of the biomass boiler 7 as described above, the high- pressure extraction valves 56a and 56b are further controlled to control the extraction amount of the high-pressure steam. Specifically, the control unit 30 controls the high pressure extraction valves 56a and 56b as follows.
When the biomass boiler 7 is not charged, that is, when the feed water is not heated by the feed water heating heat exchanger 60, the high pressure bleed valve according to the load of the boiler 3 according to the load program in the map shown in FIG. The opening degree of 56a, 56b is controlled.
　バイオマスボイラ７を投入する場合は、高圧抽気弁５６ａ，５６ｂの開度が閉となるように、すなわち高圧蒸気の抽気量を減じるように制御する。具体的には、バイオマスボイラ７によって給水加熱用熱交換器６０で給水を加熱すると、加熱量に相当する熱量に応じた高圧蒸気の抽気量を減じる。
　バイオマスボイラ７からの加熱量は、加熱用蒸気温度センサ６２Ｔと、加熱用蒸気圧力センサ６２Ｐと、加熱用蒸気流量センサ６２Ｆとから、得られたバイオマスボイラ流体熱量計算値が、バイオマスボイラ流体熱量設定値となるように、制御部３０により制御される。上述のエコノマイザ出口温度に基づく制御と燃焼排ガス温度に基づく制御の両方を満たすように制御部３０にて演算される。 When the biomass boiler 7 is charged, the high pressure extraction valves 56a and 56b are controlled to be closed, that is, the amount of extraction of high pressure steam is reduced. Specifically, when the feed water is heated by the biomass boiler 7 using the heat exchanger 60 for heating the feed water, the amount of high-pressure steam extracted according to the amount of heat corresponding to the amount of heating is reduced.
The amount of heating from the biomass boiler 7 is calculated by setting the biomass boiler fluid calorific value obtained from the heating steam temperature sensor 62T, the heating steam pressure sensor 62P, and the heating steam flow rate sensor 62F to the biomass boiler fluid calorific value. It is controlled by the control unit 30 so as to be a value. The control unit 30 calculates so as to satisfy both the control based on the economizer outlet temperature and the control based on the combustion exhaust gas temperature.
　バイオマスボイラ７による加熱量が高圧蒸気の抽気量を上回る場合には、高圧抽気弁５６ａ，５６ｂを全閉として、高圧蒸気の抽気量をゼロとする。このときの高圧抽気弁５６ａ，５６ｂを全閉とするタイミングは、バイオマスボイラ７からの加熱量との関係を予め定めた制御マップに基づいて行うのが好ましい。 When the heating amount by the biomass boiler 7 exceeds the extraction amount of the high-pressure steam, the high- pressure extraction valves 56a and 56b are fully closed, and the extraction amount of the high-pressure steam is set to zero. The timing at which the high- pressure extraction valves 56a and 56b are fully closed at this time is preferably performed based on a control map in which the relationship with the heating amount from the biomass boiler 7 is determined in advance.
　上述のように高圧抽気弁５６ａ，５６ｂの開度制御を行う場合は、以下のように行う。図６に示すように、制御部３０において、エコノマイザ出口温度の設定値（本実施形態では、エコノマイザ出口温度設定値Ｔ１ｓｅｔ）と、エコノマイザ出口温度センサ２２Ｔから得たエコノマイザ出口温度計測値との差分をとり、この差分量に応じて、先行制御またはフィードバック制御によって高圧抽気弁５６ａ，５６ｂの開度を制御する。 When the opening control of the high pressure extraction valves 56a and 56b is performed as described above, it is performed as follows. As shown in FIG. 6, in the control unit 30, the difference between the economizer outlet temperature set value (in this embodiment, the economizer outlet temperature set value T1set) and the economizer outlet temperature measured value obtained from the economizer outlet temperature sensor 22T is calculated. Therefore, the opening degree of the high pressure extraction valves 56a and 56b is controlled by the preceding control or the feedback control according to the difference amount.
　高圧タービン３４からの高圧蒸気の抽気量を減少させることによって、高圧タービン３４に流れる蒸気流量を機械的強度の規定値範囲内で増大させてタービン効率を向上させることができる。ここで第１高圧給水加熱器５４ａ，第２高圧給水加熱器５４ｂへ供給する高圧蒸気の抽気量を高圧抽気弁５６ａ，５６ｂを閉方向に制御する際には、機械的強度の規定値範囲として高圧タービン３４のタービン翼の強度が考慮される。すなわち、タービン翼の強度は、タービン翼の前後にかかる差圧に対して耐久性を有するように設計されている。この差圧は高圧タービン３４内部を通過する高圧蒸気の流量・圧力バランスによって決まるので、差圧がタービン翼の強度上の許容値を超えないようにボイラ３の負荷を考慮して高圧抽気弁５６ａ，５６ｂの開度すなわち高圧蒸気の抽気量の減少量が決定される。例えば、高圧抽気弁５６ａ，５６ｂを全閉とする際には、ＭＣＲ点（ボイラー最大連続蒸発量）のときのタービン強度が考慮される。ＭＣＲ点において高圧抽気弁５６ａ，５６ｂを全閉としてもタービン強度に余裕がある場合には、負荷１００％のときでも高圧抽気弁５６ａ，５６ｂを全閉とすることができる。またタービン強度に余裕がない場合には、負荷１００％のときのタービン強度を考慮して高圧蒸気の抽気量の減少量が決定され、高圧抽気弁５６ａ，５６ｂの開度が設定される。 By reducing the amount of high-pressure steam extracted from the high-pressure turbine 34, the flow rate of the steam flowing through the high-pressure turbine 34 can be increased within the specified range of mechanical strength, and the turbine efficiency can be improved. Here, when controlling the extraction amount of the high-pressure steam supplied to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b in the closing direction of the high- pressure extraction valves 56a and 56b, the specified range of mechanical strength is set. The strength of the turbine blades of the high pressure turbine 34 is taken into account. That is, the strength of the turbine blade is designed to have durability against the differential pressure applied before and after the turbine blade. Since this differential pressure is determined by the flow rate / pressure balance of the high-pressure steam passing through the high-pressure turbine 34, the high-pressure bleed valve 56a is considered in consideration of the load of the boiler 3 so that the differential pressure does not exceed the allowable value on the turbine blade strength. , 56b, that is, the amount of decrease in the amount of high-pressure steam extraction is determined. For example, when the high pressure bleed valves 56a and 56b are fully closed, the turbine strength at the MCR point (boiler maximum continuous evaporation amount) is considered. If the turbine strength is sufficient even when the high pressure extraction valves 56a and 56b are fully closed at the MCR point, the high pressure extraction valves 56a and 56b can be fully closed even when the load is 100%. If the turbine strength is not sufficient, the reduction amount of the high-pressure steam extraction amount is determined in consideration of the turbine strength when the load is 100%, and the openings of the high- pressure extraction valves 56a and 56b are set.
＜過熱器スプレイの制御＞
　制御部３０は、バイオマスボイラ７の加熱量が変化した際や高圧抽気弁５６ａ，５６ｂによる高圧蒸気の抽気量が変化した際に、過熱器スプレイ２７を制御する。バイオマスボイラ７の加熱量が変化すると（例えばバイオマスボイラ７の緊急停止やバイオマス燃料の発熱量変化など）、過熱器１３を出た主蒸気の温度が変化するおそれがあるので、過熱器スプレイ２７によって主蒸気温度を適正値の範囲に素早く制御する。また、第１高圧給水加熱器５４ａ，第２高圧給水加熱器５４ｂへ供給する高圧蒸気の抽気量が変化すると、過熱器１３と再熱器１７のバランスが変化するおそれがあるので、過熱器スプレイ２７によって主蒸気温度や再熱蒸気温度を適正値の範囲に素早く制御する。再熱器スプレイが設けられている場合には、過熱器スプレイ２７と協働して制御することが好ましい。したがって、バイオマスボイラ７で給水を加熱する場合には、バイオマスボイラ７で給水を加熱しない場合に比べて、冷却熱量が多く必要になり、過熱器スプレイ２７及び再熱器スプレイの噴射量の制御範囲が大きくなるので、これに対応する噴射量の制御範囲を備える過熱器スプレイ２７や再熱器スプレイが採用されると更に好ましい。 <Control of superheater spray>
The control unit 30 controls the superheater spray 27 when the amount of heating of the biomass boiler 7 changes or when the amount of high-pressure steam extracted by the high- pressure extraction valves 56a and 56b changes. When the heating amount of the biomass boiler 7 changes (for example, emergency stop of the biomass boiler 7 or change in the calorific value of the biomass fuel), the temperature of the main steam exiting the superheater 13 may change. Quickly control the main steam temperature within the appropriate range. Moreover, since the balance between the superheater 13 and the reheater 17 may change when the amount of high-pressure steam extracted to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b changes, the superheater spray may change. 27, the main steam temperature and the reheat steam temperature are quickly controlled within a range of appropriate values. When a reheater spray is provided, it is preferably controlled in cooperation with the superheater spray 27. Therefore, when heating feed water with the biomass boiler 7, compared with the case where feed water is not heated with the biomass boiler 7, the amount of cooling heat is required, and the control range of the injection amount of the superheater spray 27 and the reheater spray is required. Therefore, it is more preferable that the superheater spray 27 or the reheater spray having a control range of the injection amount corresponding to this is adopted.
＜バイオマスボイラ起動制御＞
　次に、図７を用いて、バイオマスボイラ７の起動制御について説明する。
　先ず、ステップＳ１に示すように、ボイラ３の負荷が一定以上で、バイオマスボイラ７が停止しており、第１高圧給水加熱器５４ａ，第２高圧給水加熱器５４ｂへ高圧蒸気を供給する高圧抽気弁５６ａ，５６ｂが開とされており、給水バイパス弁６８が開とされているときに、ステップＳ２に示すようにバイオマスボイラ７を起動する。これにより、バイオマスボイラ７にバイオマス燃料が投入され、蒸気の生成が行われる。このとき、図５及び図６に示したように、蒸気制御弁７２と高圧抽気弁５６ａ，５６ｂの開度制御を開始する。 <Biomass boiler activation control>
Next, activation control of the biomass boiler 7 will be described with reference to FIG.
First, as shown in step S1, the load of the boiler 3 is equal to or greater than a certain level, the biomass boiler 7 is stopped, and high-pressure extraction for supplying high-pressure steam to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b. When the valves 56a and 56b are opened and the feed water bypass valve 68 is opened, the biomass boiler 7 is started as shown in step S2. Thereby, biomass fuel is thrown into the biomass boiler 7, and the production | generation of a vapor | steam is performed. At this time, as shown in FIGS. 5 and 6, opening control of the steam control valve 72 and the high pressure extraction valves 56a and 56b is started.
　そして、ステップＳ３にて、加熱用蒸気供給配管６２に設けられた加熱用蒸気温度センサ６２Ｔによって計測されたバイオマスボイラ出口蒸気温度が、温度センサ５７Ｔで計測された給水加熱用熱交換器６０に流入する給水温度よりも所定値α以上であるかを判断する。このステップＳ３の条件を満たした場合には、ステップＳ４へ進み、満たしていない場合はステップＳ３を繰り返しバイオマスボイラ７の起動を継続する。所定値αは、給水加熱用熱交換器６０の伝熱特性から決まり、所定値αを小さくするには給水加熱用熱交換器６０の伝熱面積を大きくする必要があり、熱交換器が大型化する。例えば、所定値αは２℃～１０℃、さらに好ましくは２℃～５℃で設定される。 In step S3, the biomass boiler outlet steam temperature measured by the heating steam temperature sensor 62T provided in the heating steam supply pipe 62 flows into the feed water heating heat exchanger 60 measured by the temperature sensor 57T. It is judged whether it is more than predetermined value (alpha) rather than the water supply temperature to perform. If the condition of step S3 is satisfied, the process proceeds to step S4. If not satisfied, step S3 is repeated and the activation of the biomass boiler 7 is continued. The predetermined value α is determined from the heat transfer characteristics of the feed water heating heat exchanger 60. To reduce the predetermined value α, it is necessary to increase the heat transfer area of the feed water heating heat exchanger 60, and the heat exchanger is large. Turn into. For example, the predetermined value α is set at 2 ° C. to 10 ° C., more preferably 2 ° C. to 5 ° C.
　ステップＳ４では、給水バイパス弁６８を閉として、給水を給水加熱用熱交換器６０へと導く。このとき、蒸気制御弁７２及び高圧抽気弁５６ａ，５６ｂの制御は継続されたままである。 In step S4, the feed water bypass valve 68 is closed, and the feed water is guided to the feed water heating heat exchanger 60. At this time, the control of the steam control valve 72 and the high pressure bleed valves 56a and 56b is continued.
　給水配管２４には、エコノマイザ１８の給水入口温度を計測する温度センサ５８Ｔが設けられている。この温度センサ５８Ｔの計測値は、制御部３０へと送られる。ステップＳ５では、温度センサ５８Ｔで計測したエコノマイザ１８の給水入口温度が設定温度よりも所定値β以上であるかを判断する。このステップＳ５の条件を満たした場合には、ステップＳ６へ進み、満たしていない場合はステップＳ５を繰り返してエコノマイザ１８の給水入口温度が上昇するのを待機する。所定値βは、エコノマイザ１８の給水入口温度が設定温度を超えたことで、高圧抽気弁５６ａ，５６ｂの開度を閉へと調整可能とするもので、所定値βを小さくすると給水加熱用熱交換器６０の熱交換量に不安定な変動が発生した際に高圧抽気弁５６ａ，５６ｂの開度制御へ影響する。例えば、所定値βは２℃～５℃で設定される。 The water supply pipe 24 is provided with a temperature sensor 58T that measures the temperature of the water supply inlet of the economizer 18. The measured value of the temperature sensor 58T is sent to the control unit 30. In step S5, it is determined whether the feed water inlet temperature of the economizer 18 measured by the temperature sensor 58T is equal to or higher than a predetermined value β than the set temperature. If the condition of step S5 is satisfied, the process proceeds to step S6. If not satisfied, step S5 is repeated to wait for the temperature of the water supply inlet of the economizer 18 to rise. The predetermined value β allows the opening of the high- pressure extraction valves 56a and 56b to be closed when the feed water inlet temperature of the economizer 18 exceeds the set temperature. When an unstable fluctuation occurs in the heat exchange amount of the exchanger 60, the opening degree control of the high pressure extraction valves 56a and 56b is affected. For example, the predetermined value β is set at 2 ° C. to 5 ° C.
　ステップＳ６に進むと、高圧抽気弁５６ａ，５６ｂの開度を閉じる方向へ制御する。ただし、蒸気制御弁７２だけでなく高圧抽気弁５６ａ，５６ｂも開度制御は継続したままである。これにより、高圧蒸気の抽気量を減少させて、蒸気タービンの蒸気流量を機械的限度の規定範囲内で増大させてタービン出力が増大する。また、蒸気の抽気量を減少させる前と後とを比較するにあたり、同じタービン出力となるようにボイラから蒸気タービンへ供給される総蒸気量を調整した場合は、抽気量を減少することによって、総蒸気流量を減少させることができるので、タービン効率を向上させることができる。タービン効率が向上することによりボイラ３の負荷に対する発電効率が向上する。バイオマスボイラ７による給水への加熱後の発電出力が変わらない条件では、ボイラ３に投入する化石燃料量を低減できることになり、カーボンニュートラルとならない二酸化炭素の排出量が削減できる。以上により、バイオマスボイラ７の投入が完了し起動制御が終了する（ステップＳ７）。 In step S6, the opening degree of the high pressure bleed valves 56a and 56b is controlled in the closing direction. However, not only the steam control valve 72 but also the high pressure bleed valves 56a and 56b continue to control the opening degree. As a result, the extraction amount of the high-pressure steam is decreased, the steam flow rate of the steam turbine is increased within the specified range of the mechanical limit, and the turbine output is increased. In addition, when comparing the amount before and after reducing the amount of steam extracted, if the total amount of steam supplied from the boiler to the steam turbine is adjusted so as to have the same turbine output, by reducing the amount of extraction, Since the total steam flow can be reduced, turbine efficiency can be improved. By improving the turbine efficiency, the power generation efficiency with respect to the load of the boiler 3 is improved. Under the condition that the power generation output after heating to the feed water by the biomass boiler 7 does not change, the amount of fossil fuel input to the boiler 3 can be reduced, and the amount of carbon dioxide emissions that do not become carbon neutral can be reduced. Thus, the introduction of the biomass boiler 7 is completed and the start-up control is finished (step S7).
　起動制御が終了すると、前述のように、バイオマスボイラ７の加熱量と、第１高圧給水加熱器５４ａ，第２高圧給水加熱器５４ｂへ供給する高圧蒸気の抽気量と、過熱器スプレイ２７による主蒸気の温度とを制御して、発電プラント１の負荷に応じた適正なボイラ３とバイオマスボイラ７と蒸気タービン５の運転を行う。
　バイオマスボイラ７の加熱量は、加熱用蒸気温度センサ６２Ｔと、加熱用蒸気圧力センサ６２Ｐと、加熱用蒸気流量センサ６２Ｆとから得られたバイオマスボイラ流体熱量計算値が、バイオマスボイラ流体熱量設定値となるように、制御部３０により制御される。このバイオマスボイラ流体熱量設定値は、エコノマイザ出口温度に基づく制御と燃焼排ガス温度に基づく制御の両方を満たすように発電プラント１全体のヒートバランスから予め計算で設定されたものである。
　また、第１高圧給水加熱器５４ａ，第２高圧給水加熱器５４ｂへ供給する高圧蒸気の抽気は、タービン翼の前後にかかる差圧がタービン翼の強度上の許容値を超えないように、高圧抽気弁５６ａ，５６ｂを閉方向に開度を設定し制御される。
　さらに、バイオマスボイラ７の加熱量や、高圧抽気弁５６ａ，５６ｂによる高圧蒸気の抽気量が変化した際に、主蒸気の温度は、過熱器スプレイ２７によりを適正値の範囲に素早く制御される。 When the start-up control is finished, as described above, the heating amount of the biomass boiler 7, the extraction amount of the high-pressure steam supplied to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b, and the main heater 27 are used. By controlling the temperature of the steam, the appropriate boiler 3, biomass boiler 7 and steam turbine 5 are operated according to the load of the power plant 1.
The heating amount of the biomass boiler 7 is calculated as follows. The calculated value of the biomass boiler fluid calorific value obtained from the heating steam temperature sensor 62T, the heating steam pressure sensor 62P, and the heating steam flow rate sensor 62F is the biomass boiler fluid calorific value set value. It is controlled by the control part 30 so that it may become. This biomass boiler fluid calorific value set value is set in advance from the heat balance of the entire power plant 1 so as to satisfy both the control based on the economizer outlet temperature and the control based on the combustion exhaust gas temperature.
Further, the extraction of the high-pressure steam supplied to the first high-pressure feed water heater 54a and the second high-pressure feed water heater 54b is performed so that the differential pressure applied before and after the turbine blade does not exceed the allowable value on the strength of the turbine blade. The bleed valves 56a and 56b are controlled by setting the opening in the closing direction.
Further, when the amount of heating of the biomass boiler 7 and the amount of high-pressure steam extracted by the high- pressure extraction valves 56a and 56b change, the temperature of the main steam is quickly controlled by the superheater spray 27 to a range of appropriate values.
＜バイオマスボイラ切離制御＞
　次に、図８を用いて、バイオマスボイラ７による給水加熱を切り離す切離制御について説明する。
　先ず、ステップＳ１１に示すように、ボイラ３の負荷が一定以上で、バイオマスボイラ７が起動しており、高圧抽気弁５６ａ，５６ｂが閉とされており、給水バイパス弁６８が閉とされているときに、ステップＳ１２に示すようにバイオマスボイラ７を停止する。このとき、図５に示した蒸気制御弁７２の開度制御を停止し、かつ、図６に示した高圧抽気弁５６ａ，５６ｂの開度制御を停止する。ただし、高圧抽気弁５６ａ，５６ｂの開度は、図３に示したロードプログラムに従って制御される。 <Biomass boiler separation control>
Next, the separation control for separating the feed water heating by the biomass boiler 7 will be described with reference to FIG.
First, as shown in step S11, the load on the boiler 3 is equal to or greater than a certain level, the biomass boiler 7 is activated, the high pressure extraction valves 56a and 56b are closed, and the feed water bypass valve 68 is closed. Sometimes, the biomass boiler 7 is stopped as shown in step S12. At this time, the opening degree control of the steam control valve 72 shown in FIG. 5 is stopped, and the opening degree control of the high pressure extraction valves 56a and 56b shown in FIG. 6 is stopped. However, the openings of the high pressure bleed valves 56a and 56b are controlled according to the load program shown in FIG.
　そして、ステップＳ１３にて、温度センサ５８Ｔで計測されたエコノマイザ１８の給水入口温度が設定温度に所定値βを加えた値よりも低いかを判断する。このステップＳ１３の条件を満たした場合には、ステップＳ１４へ進み、満たしていない場合はステップＳ１３を繰り返す。所定値βは、エコノマイザ１８の給水入口温度が設定温度を超えたことで、高圧抽気弁５６ａ，５６ｂの開度を開へと調整可能とするもので、所定値βを小さくすると給水加熱用熱交換器６０の熱交換量に不安定な変動が発生した際に高圧抽気弁５６ａ，５６ｂの開度制御へ影響する。例えば、所定値βは２℃～５℃で設定される。 In step S13, it is determined whether the feed water inlet temperature of the economizer 18 measured by the temperature sensor 58T is lower than a value obtained by adding a predetermined value β to the set temperature. If the condition of step S13 is satisfied, the process proceeds to step S14. If not satisfied, step S13 is repeated. The predetermined value β makes it possible to adjust the opening degree of the high pressure extraction valves 56a and 56b to be open when the feed water inlet temperature of the economizer 18 exceeds the set temperature. When an unstable fluctuation occurs in the heat exchange amount of the exchanger 60, the opening degree control of the high pressure extraction valves 56a and 56b is affected. For example, the predetermined value β is set at 2 ° C. to 5 ° C.
　ステップＳ１４では、給水バイパス弁６８を閉としたままで、高圧抽気弁５６ａ，５６ｂは開とし、図３に示したロードプログラムに従って開度制御する。 In step S14, the high pressure extraction valves 56a and 56b are opened while the feed water bypass valve 68 is closed, and the opening degree is controlled according to the load program shown in FIG.
　ステップＳ１５では、加熱用蒸気供給配管６２に設けられた加熱用蒸気温度センサ６２Ｔによって計測されたバイオマスボイラ出口蒸気温度が、温度センサ５７Ｔで計測された給水加熱用熱交換器６０に流入する給水温度に所定値αを加えた値よりも低いかを判断する。このステップＳ１５の条件を満たした場合には、ステップＳ１６へ進み、満たしていない場合はステップＳ１５を繰り返す。所定値αは、給水加熱用熱交換器６０の伝熱特性から決まり、所定値αを小さくするには給水加熱用熱交換器６０の伝熱面積を大きくする必要があり、熱交換器が大型化する。例えば、所定値αは２℃～１０℃、さらに好ましくは２℃～５℃で設定される。 In step S15, the feed water temperature at which the biomass boiler outlet steam temperature measured by the heating steam temperature sensor 62T provided in the heating steam supply pipe 62 flows into the feed water heating heat exchanger 60 measured by the temperature sensor 57T. It is determined whether the value is lower than a value obtained by adding a predetermined value α to the value. If the condition of step S15 is satisfied, the process proceeds to step S16. If not satisfied, step S15 is repeated. The predetermined value α is determined from the heat transfer characteristics of the feed water heating heat exchanger 60. To reduce the predetermined value α, it is necessary to increase the heat transfer area of the feed water heating heat exchanger 60, and the heat exchanger is large. Turn into. For example, the predetermined value α is set at 2 ° C. to 10 ° C., more preferably 2 ° C. to 5 ° C.
　ステップＳ１６に進むと、高圧抽気弁５６ａ，５６ｂの開度を開とし、図３に示したロードプログラムに従って開度制御したままで、給水バイパス弁６８を開とする。これにより、給水は給水加熱用熱交換器６０をバイパスして、バイオマスボイラ７による給水加熱を停止する。以上により、バイオマスボイラ７の切離制御が完了する（ステップＳ１７）。 In step S16, the opening of the high pressure bleed valves 56a and 56b is opened, and the feed water bypass valve 68 is opened while the opening is controlled according to the load program shown in FIG. Thereby, feed water bypasses the heat exchanger 60 for feed water heating, and feed water heating by the biomass boiler 7 is stopped. Thus, the separation control of the biomass boiler 7 is completed (step S17).
　図９及び図１０には、本実施形態のようにバイオマスボイラ７による給水加熱を行う場合（バイオマスボイラ追設後）と、比較例としてバイオマスボイラ７による給水加熱を行わない場合（バイオマスボイラ追設前）との効果の一例について説明する。 In FIG.9 and FIG.10, when feed water heating by the biomass boiler 7 is performed like this embodiment (after biomass boiler additional installation), and when the feed water heating by the biomass boiler 7 is not performed as a comparative example (biomass boiler additional installation) An example of the effect of (before) will be described.
　図９において、横軸は発電プラント１の出力、縦軸はバイオマスボイラ７から給水に与えられた加熱量を示す。図９に示すように、バイオマスボイラ７による給水加熱によって、熱量は給水へ与えられる。同図では、出力１００％のときに給水に与えられる熱量を１．０として相対値として表している。 9, the horizontal axis represents the output of the power plant 1 and the vertical axis represents the amount of heating given to the feed water from the biomass boiler 7. As shown in FIG. 9, the amount of heat is given to the feed water by the feed water heating by the biomass boiler 7. In the figure, the amount of heat given to the water supply when the output is 100% is expressed as a relative value with 1.0.
　図１０において、横軸は発電プラントの出力、縦軸である発電効率は、発電プラントへ投入する化石燃料エネルギに対する発電効率を示している。同図において、出力１００％のときのバイオマスボイラ追設前の発電効率を１．０として相対値として表している。同図から分かるように、バイオマスボイラからのエネルギが投入されるので発電プラント１の出力が変化しても、バイオマスボイラ追設後はバイオマスボイラ追設前よりも発電効率が高くなるが、特に発電プラント１の出力が低い場合には、発電効率の上昇割合が大きい。これば、発電出力が小さいときは蒸気タービンのタービン効率が低下するが、給水加熱による効果と高圧蒸気の抽気量を減少させた効果は、発電出力が低負荷となるほどタービン効率の向上に大きく寄与するからである。
　なお図７における発電効率とは、（得られる電気エネルギ）÷（投入する化石燃料のエネルギ）と定義している。また、タービン効率とは、（得られる電気エネルギ）÷［（タービンへ流入する蒸気のエネルギ）－（タービンから流出する蒸気のエネルギ）］と定義している。 In FIG. 10, the horizontal axis indicates the output of the power plant, and the power generation efficiency on the vertical axis indicates the power generation efficiency with respect to fossil fuel energy input to the power plant. In the figure, the power generation efficiency before the biomass boiler additional installation when the output is 100% is represented as 1.0 as a relative value. As can be seen from the figure, since the energy from the biomass boiler is input, even if the output of the power plant 1 changes, the power generation efficiency is higher after the biomass boiler is added than before the biomass boiler is added. When the output of the plant 1 is low, the rate of increase in power generation efficiency is large. In this case, the turbine efficiency of the steam turbine decreases when the power generation output is small, but the effect of heating the feedwater and the effect of reducing the extraction amount of high-pressure steam greatly contribute to the improvement of the turbine efficiency as the power generation output becomes lower. Because it does.
The power generation efficiency in FIG. 7 is defined as (electric energy obtained) / (energy of fossil fuel to be input). The turbine efficiency is defined as (obtained electric energy) / [(energy of steam flowing into the turbine) − (energy of steam flowing out of the turbine)].
　図１１Ａ及びＢは、発電プラント１の発電により得られる電気エネルギと発電プラント１（ボイラ３およびバイオマスボイラ７）へ投入する燃料エネルギの関係と内訳を示している。ここでは、発電プラント１の出力を例えば中間の５０％とした場合を比較している。なお、図１１Ａはバイオマスボイラ７の追設前、図１１Ｂがバイオマスボイラ７の追設後を示している。バイオマスボイラ７の追設前と追設後の発電により得られる電気エネルギを同量とした場合、図１１Ｂ（バイオマスボイラ７の追設後）に示されるように、バイオマスボイラ追設後の燃料エネルギは化石燃料の投入量が低減され、カーボンニュートラルとならない二酸化炭素の排出量が削減できる。 11A and 11B show the relationship and breakdown between the electric energy obtained by the power generation of the power plant 1 and the fuel energy to be input to the power plant 1 (boiler 3 and biomass boiler 7). Here, the case where the output of the power plant 1 is set to 50% in the middle is compared. 11A shows before the biomass boiler 7 is additionally installed, and FIG. 11B shows the biomass boiler 7 after the additional installation. When the electric energy obtained by the power generation before and after the additional installation of the biomass boiler 7 is the same amount, as shown in FIG. 11B (after the additional installation of the biomass boiler 7), the fuel energy after the additional installation of the biomass boiler Reduces the amount of fossil fuel input and reduces carbon dioxide emissions that are not carbon neutral.
　具体的には、バイオマスボイラ７で発生した蒸気をボイラ３へ供給する給水の加熱に利用し、蒸気タービン５からの蒸気の抽気量を減少（抽気量低減）させ、更にボイラ３へ供給される給水を飽和温度より所定範囲で低く飽和温度に近い温度となるように加熱する（給水エンタルピ増加させる）ことによるエネルギ変化分に相応して、ボイラ３に投入する化石燃料を更に低減でき、カーボンニュートラルとならない二酸化炭素の排出量をより削減できる。 Specifically, the steam generated in the biomass boiler 7 is used for heating the feed water supplied to the boiler 3, the amount of steam extracted from the steam turbine 5 is reduced (the amount of extraction reduced), and further supplied to the boiler 3. The fossil fuel to be charged into the boiler 3 can be further reduced in accordance with the energy change caused by heating the feed water to a temperature lower than the saturation temperature within a predetermined range and close to the saturation temperature (increasing the feed water enthalpy), and carbon neutral. The amount of carbon dioxide that cannot be reduced can be further reduced.
　上述した実施形態によれば、以下の作用効果を奏する。
　ボイラ３に供給される給水をバイオマスボイラ７によって加熱することで、ボイラ３に供給される給水のエンタルピを増大させて、タービン効率を向上して発電効率を向上させることができる。さらに、エコノマイザ１８の出口水温度が蒸気化しないように飽和温度未満でかつ飽和温度に近い温度となるようにバイオマスボイラ７の加熱量を制御することとしたので、給水を可能な限り加熱することができる。これにより、給水のエンタルピを増大させて、タービン効率を向上して発電効率を向上させることができる。これにより、発電効率が向上する前の発電量と同等の発電する場合、ボイラ３に投入する化石燃料を減少でき、カーボンニュートラルとならない二酸化炭素の排出量が削減できる。 According to embodiment mentioned above, there exist the following effects.
By heating the feed water supplied to the boiler 3 with the biomass boiler 7, the enthalpy of the feed water supplied to the boiler 3 can be increased, turbine efficiency can be improved and power generation efficiency can be improved. Furthermore, since the heating amount of the biomass boiler 7 is controlled so that the outlet water temperature of the economizer 18 is less than the saturation temperature and close to the saturation temperature so as not to be vaporized, the water supply is heated as much as possible. Can do. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved. As a result, when generating the same amount of power as before the power generation efficiency is improved, the amount of fossil fuel input to the boiler 3 can be reduced, and the amount of carbon dioxide that does not become carbon neutral can be reduced.
　脱硝装置の上限温度未満でかつ上限温度に近い排ガス温度となるようにバイオマスボイラ７の加熱量を制御することとしたので、給水を可能な限り加熱することができる。これにより、給水のエンタルピを増大させて、タービン効率を向上して発電効率を向上させることができる。 Since the heating amount of the biomass boiler 7 is controlled so that the exhaust gas temperature is lower than the upper limit temperature of the denitration apparatus and close to the upper limit temperature, the feed water can be heated as much as possible. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved.
　バイオマスボイラ７にて発生した蒸気の一部を排出する蒸気制御弁７２を開とすることで、発生蒸気の一部を排出してボイラ３に供給される給水の加熱量を減少させて調整することができる。これにより、バイオマスボイラ７に投入されるバイオマス燃料の性状や発熱量が変動した場合などにバイオマスボイラ７にて発生する蒸気条件が変動しても、バイオマスボイラ７によって加熱されるボイラ３の給水の加熱量を所望値に調整することができる。 By opening the steam control valve 72 that discharges a part of the steam generated in the biomass boiler 7, the heating amount of the feed water supplied to the boiler 3 is reduced by adjusting a part of the generated steam. be able to. As a result, even if the steam conditions generated in the biomass boiler 7 fluctuate when the properties and heat value of the biomass fuel input to the biomass boiler 7 fluctuate, the feed water of the boiler 3 heated by the biomass boiler 7 is changed. The amount of heating can be adjusted to a desired value.
　図１２Ａ及びＢには、蒸気制御弁７２を用いた加熱量の制御の有無についての比較例が示されている。図１２Ａは、蒸気制御弁７２もしくは加熱蒸気用スプレイ７３の制御を用いない場合であり、図１２Ｂはバイオマスボイラ流体熱量計算値がバイオマスボイラ流体熱量設定値となるように、蒸気制御弁７２もしくは加熱蒸気用スプレイ７３の制御を用いた場合である。
　図１２Ａから分かるように、蒸気制御弁７２もしくは加熱蒸気用スプレイ７３の制御を用いない場合は、バイオマスボイラ７で発生した蒸気（バイオマスボイラ出口流体）の圧力、温度及び流量が時間に対して変動すると、給水加熱用熱交換器６０での熱交換量は、圧力、温度及び流量に応じて変動する。したがって、エコノマイザ１８の入口の給水熱量（ＥＣＯ入口給水熱量）も圧力、温度及び流量に応じて変動する。 12A and 12B show a comparative example regarding the presence or absence of control of the heating amount using the steam control valve 72. FIG. FIG. 12A shows a case where the control of the steam control valve 72 or the heating steam spray 73 is not used, and FIG. 12B shows the steam control valve 72 or heating so that the calculated value of the biomass boiler fluid calorific value becomes the biomass boiler fluid calorific value set value. This is a case where the control of the steam spray 73 is used.
As can be seen from FIG. 12A, when the control of the steam control valve 72 or the heating steam spray 73 is not used, the pressure, temperature, and flow rate of steam (biomass boiler outlet fluid) generated in the biomass boiler 7 fluctuate with time. Then, the heat exchange amount in the feed water heating heat exchanger 60 varies according to the pressure, temperature, and flow rate. Accordingly, the amount of heat supplied to the economizer 18 at the inlet (ECO inlet water supplied) also varies depending on the pressure, temperature, and flow rate.
　これに対して、図１２Ｂから分かるように、バイオマスボイラ流体熱量計算値がバイオマスボイラ流体熱量設定値となるように、蒸気制御弁７２もしくは加熱蒸気用スプレイ７３の制御を用いる場合は、バイオマス燃料の発熱量変化などによりバイオマスボイラ出口流体の圧力、温度及び流量が時間に対して変動しても、給水加熱用熱交換器６０での熱交換量およびＥＣＯ入口給水熱量は一定となる。このように、バイオマスボイラ７の投入燃料の性状変化等によってバイオマスボイラ７の出力が変化しても、ボイラ３の運転性能に影響を及ぼすことがない。 On the other hand, as can be seen from FIG. 12B, when the control of the steam control valve 72 or the heating steam spray 73 is used so that the biomass boiler fluid calorie calculated value becomes the biomass boiler fluid calorie set value, Even if the pressure, temperature, and flow rate of the biomass boiler outlet fluid fluctuate with time due to changes in the amount of heat generated, the heat exchange amount in the feed water heating heat exchanger 60 and the ECO inlet feed water heat amount are constant. Thus, even if the output of the biomass boiler 7 changes due to the change in the properties of the input fuel of the biomass boiler 7, the operation performance of the boiler 3 is not affected.
　蒸気タービン５から抽気される蒸気量を高圧抽気弁５６ａ，５６ｂによって調整することによって高圧給水加熱器５４ａ，５４ｂにおける加熱量を制御し、エコノマイザ１８へ供給される給水温度を制御することとした。そして、バイオマスボイラ７によって給水加熱用熱交換器６０にて加熱された給水温度に基づいて蒸気タービン５から抽気される蒸気の抽気量を制御することとしたので、エコノマイザ１８に供給される給水温度を所望値に制御することができる。 The amount of steam extracted from the steam turbine 5 is adjusted by the high- pressure extraction valves 56a and 56b to control the heating amount in the high-pressure feed water heaters 54a and 54b, and the feed water temperature supplied to the economizer 18 is controlled. And since it decided to control the extraction amount of the steam extracted from the steam turbine 5 based on the feed water temperature heated with the biomass boiler 7 in the feed water heating heat exchanger 60, the feed water temperature supplied to the economizer 18 Can be controlled to a desired value.
　蒸気タービン５の機械的強度の規定値範囲としてのタービン翼の強度は、タービン翼の前後にかかる差圧に耐久するように設計されていて、この差圧は蒸気タービン５へ流通する蒸気の流量および圧力バランスによって決まり、この差圧は抽気量に応じて変化する。そこで、タービン翼の強度を考慮して蒸気の抽気量を制御することとした。これにより、タービン翼の強度を考慮して抽気量を可能な限り減少させて蒸気タービン５に流れる総蒸気流量を減少させることができ、タービン効率をさらに向上させることができる。 The strength of the turbine blades as a specified value range of the mechanical strength of the steam turbine 5 is designed to withstand the differential pressure applied before and after the turbine blades, and this differential pressure is the flow rate of steam flowing to the steam turbine 5. The pressure difference is determined according to the amount of bleed air. Therefore, the steam extraction amount is controlled in consideration of the strength of the turbine blade. As a result, the amount of extraction can be reduced as much as possible in consideration of the strength of the turbine blades, the total steam flow flowing into the steam turbine 5 can be reduced, and the turbine efficiency can be further improved.
　バイオマスボイラ７の加熱量や蒸気タービン５の蒸気の抽気量の変化によって過熱器１３から供給される過熱蒸気の温度が変動するおそれがある。この過熱蒸気の温度変動を過熱器スプレイ２７によって抑制することで、高温高圧下で使用される蒸気配管やタービン翼の温度を規定値以内に素早く設定することができ、劣化や損傷を抑制することができる。また、再熱器１７から供給される再熱蒸気の温度を制御する再熱器スプレイの流量も併せて制御することとしたので、再熱蒸気の温度を所望値に容易に制御することができる。 The temperature of the superheated steam supplied from the superheater 13 may fluctuate due to changes in the amount of heating of the biomass boiler 7 and the amount of steam extracted from the steam turbine 5. By suppressing the temperature fluctuation of the superheated steam with the superheater spray 27, the temperature of the steam pipes and turbine blades used under high temperature and high pressure can be quickly set within a specified value, and deterioration and damage can be suppressed. Can do. In addition, since the flow rate of the reheater spray that controls the temperature of the reheat steam supplied from the reheater 17 is also controlled, the temperature of the reheat steam can be easily controlled to a desired value. .
　エコノマイザ１８の出口水温度が蒸気化しないように飽和温度未満でかつ飽和温度に近い温度となるようにバイオマスボイラ７の加熱量を制御することとしたので、給水を可能な限り加熱することができる。これにより、給水のエンタルピを増大させて、タービン効率を向上して発電効率を向上させることができる。これにより、発電効率が向上する前の発電量と同等の発電する場合、ボイラ３に投入する化石燃料を減少でき、カーボンニュートラルとならない二酸化炭素の排出量が削減できる。 Since the heating amount of the biomass boiler 7 is controlled so that the outlet water temperature of the economizer 18 is less than the saturation temperature and close to the saturation temperature so as not to be vaporized, the feed water can be heated as much as possible. . Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved. As a result, when generating the same amount of power as before the power generation efficiency is improved, the amount of fossil fuel input to the boiler 3 can be reduced, and the amount of carbon dioxide that does not become carbon neutral can be reduced.
　脱硝装置の上限温度未満でかつ上限温度に近い低い排ガス温度となるようにバイオマスボイラ７の加熱量を制御することとしたので、給水を可能な限り加熱することができる。これにより、給水のエンタルピを増大させて、タービン効率を向上して発電効率を向上させることができる。 Since the heating amount of the biomass boiler 7 is controlled so that the exhaust gas temperature is lower than the upper limit temperature of the denitration apparatus and close to the upper limit temperature, the feed water can be heated as much as possible. Thereby, the enthalpy of water supply can be increased, turbine efficiency can be improved and power generation efficiency can be improved.
　給水を加熱する追加的なボイラとして、バイオマス燃料を主燃料として用いるバイオマスボイラ７とすることで、ボイラ３にてバイオマス燃料を混焼させずにバイオマスボイラ７でバイオマス燃料を専焼させることができる。したがって、ボイラ３で燃焼させる化石燃料に対するバイオマス燃料の使用比率を高めることができ、カーボンニュートラルとならない二酸化炭素の発生量を削減できる。また、腐食成分を含む廉価なバイオマス燃料をボイラ３本体の燃焼に影響を及ぼすことなく用いることができ、低い燃料コストで高効率な発電を行うことができる。 By using the biomass boiler 7 that uses biomass fuel as the main fuel as an additional boiler that heats the feed water, the biomass fuel can be exclusively burned in the biomass boiler 7 without co-firing the biomass fuel in the boiler 3. Therefore, the usage ratio of biomass fuel to fossil fuel burned in the boiler 3 can be increased, and the amount of carbon dioxide that does not become carbon neutral can be reduced. Moreover, inexpensive biomass fuel containing a corrosive component can be used without affecting the combustion of the boiler 3 main body, and highly efficient power generation can be performed at a low fuel cost.
［変形例］
　図５及び図６を用いて説明した蒸気制御弁７２及び高圧抽気弁５６ａ，５６ｂの開度制御は、図１３のように変形することができる。すなわち、バイオマスボイラ７から給水加熱用熱交換器６０に出力する熱量の設定値であるバイオマスボイラ流体熱量設定値と、バイオマスボイラ流体熱量計算値との差分をとり、この差分量に応じて、先行制御またはフィードバック制御するときの制御量と、エコノマイザ出口温度の設定値と、エコノマイザ出口温度計測値との差分をとり、この差分量に応じて、先行制御またはフィードバック制御するときの制御量とを比較し、低値選択をする。そして、低値選択をした制御量に基づいて、蒸気制御弁７２及び高圧抽気弁５６ａ，５６ｂの開度を制御する。低値選択することにより、給水系統の温度（熱量）を下げる側の制御を優先する。もし、給水温度を上げる指示であってもより制御量の小さい方を低値選択することで、エコノマイザ１８にて蒸気が発生するエコノマイザスチーミングを防止して設備の健全性を確保することができる。例えば、蒸気制御弁７２は、バイオマスボイラ流体熱量の制御により給水系統の温度を上げる指示をした場合であっても、エコノマイザ出口温度の制御が温度を下げる指示をした場合には、低値選択により温度を下げる制御を優先する。
　このような制御を行うことで、バイオマスボイラ７の出力変動の抑制をバイオマスボイラ流体熱量で制御しながら、蒸気タービン５から抽気される蒸気量を低減してエコノマイザ１８の出口水温度が蒸気化の防止をする飽和温度に近い温度となるように加熱する制御との両方を必ず達成することができる。 [Modification]
The opening control of the steam control valve 72 and the high pressure extraction valves 56a and 56b described with reference to FIGS. 5 and 6 can be modified as shown in FIG. That is, the difference between the biomass boiler fluid calorific value setting value, which is the calorific value set value output from the biomass boiler 7 to the feed water heating heat exchanger 60, and the biomass boiler fluid calorific value calculation value is calculated. Take the difference between the control amount for control or feedback control, the set value of the economizer outlet temperature, and the measured value of the economizer outlet temperature, and compare the control amount for the preceding control or feedback control according to this difference amount And select a low value. Then, based on the control value for which the low value is selected, the opening degree of the steam control valve 72 and the high pressure extraction valves 56a and 56b is controlled. By selecting a low value, priority is given to control on the side of lowering the temperature (heat amount) of the water supply system. Even if it is an instruction to raise the feed water temperature, by selecting a lower value with a smaller control amount, economizer steaming in which steam is generated in the economizer 18 can be prevented and the soundness of the equipment can be ensured. . For example, even when the steam control valve 72 is instructed to increase the temperature of the feed water system by controlling the biomass boiler fluid calorific value, the control of the economizer outlet temperature is instructed to lower the temperature by selecting a low value. Give priority to control to lower temperature.
By performing such control, while controlling the output fluctuation of the biomass boiler 7 with the biomass boiler fluid calorific value, the amount of steam extracted from the steam turbine 5 is reduced, and the outlet water temperature of the economizer 18 is vaporized. Both the control of heating to a temperature close to the saturation temperature for prevention can always be achieved.
　なお、上述した実施形態では、エコノマイザ１８の出口温度２２Ｔに基づいてバイオマスボイラ７の加熱量を制御することとしたが、エコノマイザ１８の出口温度２２Ｔに代えてエコノマイザ１８の入口温度を用いることとしても良い。
　また、給水を加熱する追加的な蒸気発生装置としてバイオマスボイラ７を用いることとしたが、必ずしも燃料にバイオマスを用いなくともよい。燃料としては例えばゴミや燃焼可能な廃棄物などを用いることができる。
　また、給水加熱用熱交換器６０は、給水加熱器５０，５２ａ，５２ｂ，５４ａ，５４ｂに対して直列に配置することとしたが、給水加熱器５０，５２ａ，５２ｂ，５４ａ，５４ｂの少なくともいずれかに対して並列に配置することとしても良い。 In the embodiment described above, the heating amount of the biomass boiler 7 is controlled based on the outlet temperature 22T of the economizer 18, but the inlet temperature of the economizer 18 may be used instead of the outlet temperature 22T of the economizer 18. good.
Moreover, although the biomass boiler 7 was used as an additional steam generator for heating feed water, it is not always necessary to use biomass as fuel. For example, garbage or combustible waste can be used as the fuel.
The feed water heating heat exchanger 60 is arranged in series with respect to the feed water heaters 50, 52a, 52b, 54a, 54b, but at least any of the feed water heaters 50, 52a, 52b, 54a, 54b. It is good also as arrange | positioning in parallel with respect to this.
１　発電プラント
３　ボイラ
３ａ　ボイラ本体
５　蒸気タービン
７　バイオマスボイラ（給水加熱用ボイラ）
１０　火炉
１１　バーナ
１２　水冷壁
１３　過熱器
１５　蒸気ドラム
１７　再熱器
１８　エコノマイザ
２０　循環ポンプ
２２　エコノマイザ出口配管
２２Ｔ　エコノマイザ出口温度センサ
２２Ｐ　エコノマイザ出口圧力センサ
２４　給水配管
２５Ｔ　燃焼排ガス温度センサ
２７　過熱器スプレイ
３０　制御部
３２　主蒸気配管
３４　高圧タービン
３５　中圧タービン
３６　低圧タービン
３７　発電機
３８　高圧タービン出口配管
４０　再熱蒸気供給配管
４２　中圧タービン出口配管
４４　低圧タービン出口配管
４６　復水器
４８　復水ポンプ
５０　低圧給水加熱器
５１　給水ポンプ
５２ａ　第１中圧給水加熱器
５２ｂ　第２中圧給水加熱器
５４ａ　第１高圧給水加熱器
５４ｂ　第２高圧給水加熱器
５５ａ　第１高圧抽気配管
５５ｂ　第２高圧抽気配管
５６ａ　第１高圧抽気弁
５６ｂ　第２高圧抽気弁
５７Ｔ　温度センサ
５８Ｔ　温度センサ
６０　給水加熱用熱交換器
６１　加熱用伝熱管
６２　加熱用蒸気供給配管
６２Ｔ　加熱用蒸気温度センサ
６２Ｐ　加熱用蒸気圧力センサ
６２Ｆ　加熱用蒸気流量センサ
６４　返送配管
６５　返送ポンプ
６７　給水バイパス配管
６８　給水バイパス弁
７２　蒸気制御弁
７３　加熱蒸気用スプレイ（スプレイ水供給手段） 1 Power Plant 3 Boiler 3a Boiler Body 5 Steam Turbine 7 Biomass Boiler (Boiler for Heating Water Supply)
10 furnace 11 burner 12 water cooling wall 13 superheater 15 steam drum 17 reheater 18 economizer 20 circulating pump 22 economizer outlet piping 22T economizer outlet temperature sensor 22P economizer outlet pressure sensor 24 water supply piping 25T combustion exhaust gas temperature sensor 27 superheater spray 30 control Portion 32 Main steam pipe 34 High pressure turbine 35 Medium pressure turbine 36 Low pressure turbine 37 Generator 38 High pressure turbine outlet pipe 40 Reheat steam supply pipe 42 Medium pressure turbine outlet pipe 44 Low pressure turbine outlet pipe 46 Condenser 48 Condensate pump 50 Low pressure Feed water heater 51 Feed water pump 52a First medium pressure feed water heater 52b Second medium pressure feed water heater 54a First high pressure feed water heater 54b Second high pressure feed water heater 55a First high pressure bleed pipe 55b Second high pressure bleed pipe 56a First 1 High pressure extraction valve 56b Second high pressure extraction Valve 57T Temperature sensor 58T Temperature sensor 60 Heat exchanger for feed water heating 61 Heat transfer pipe 62 Heating steam supply pipe 62T Heating steam temperature sensor 62P Heating steam pressure sensor 62F Heating steam flow sensor 64 Return pipe 65 Return pump 67 Water supply bypass piping 68 Water supply bypass valve 72 Steam control valve 73 Spray for heating steam (spray water supply means)

Claims (11)

  1. 　エコノマイザ及び過熱器を備えるボイラと、
    　該ボイラにて生成された蒸気によって駆動される蒸気タービンと、
    　該蒸気タービンによって駆動される発電機と、
    　前記ボイラに供給される給水を加熱する給水加熱用ボイラと、
    　前記給水加熱用ボイラで発生した加熱流体と前記ボイラへ供給される前記給水とを熱交換する給水加熱用熱交換器と、
    　該給水加熱用ボイラによる前記給水の加熱量を制御する制御部と、
    を備え、
    　前記制御部は、前記給水加熱用ボイラにより出力される前記加熱流体の熱量によって前記給水の加熱量を制御する発電プラント。     A boiler equipped with an economizer and a superheater;
    A steam turbine driven by steam generated in the boiler;
    A generator driven by the steam turbine;
    A feed water heating boiler for heating feed water supplied to the boiler;
    A feed water heating heat exchanger that exchanges heat between the heating fluid generated in the feed water heating boiler and the feed water supplied to the boiler;
    A control unit for controlling the heating amount of the feed water by the feed water heating boiler;
    With
    The said control part is a power generation plant which controls the heating amount of the said feed water with the heat amount of the said heating fluid output by the said boiler for heating feed water.
  2. 　前記制御部は、前記加熱流体の熱量を、該加熱流体の温度、圧力及び流量から算出し、所定の設定値との差分量に応じて前記給水の加熱量を制御する請求項１に記載の発電プラント。 The said control part calculates the calorie | heat amount of the said heating fluid from the temperature, pressure, and flow volume of this heating fluid, and controls the heating amount of the said water supply according to difference amount with a predetermined setting value. Power plant.
  3. 　前記制御部は、前記給水加熱用ボイラで発生した蒸気の一部を排出する蒸気制御弁、及び／又は、前記給水加熱用ボイラで発生した蒸気に対してスプレイ水を供給するスプレイ水供給手段を制御する請求項１又は２に記載の発電プラント。 The control unit includes a steam control valve that discharges a part of the steam generated in the feed water heating boiler, and / or spray water supply means that supplies spray water to the steam generated in the feed water heating boiler. The power plant according to claim 1 or 2 to be controlled.
  4. 　前記蒸気タービンから抽気した蒸気によって前記給水を加熱する給水加熱器を備え、
    　前記制御部は、前記給水熱用ボイラによって加熱された給水温度に応じて、前記給水加熱器に供給される蒸気の抽気量を制御する請求項１から３のいずれかに記載の発電プラント。     A feed water heater for heating the feed water with steam extracted from the steam turbine;
    The power plant according to any one of claims 1 to 3, wherein the control unit controls an extraction amount of steam supplied to the feed water heater according to a feed water temperature heated by the feed water heat boiler.
  5. 　前記蒸気タービンから抽気した蒸気によって前記給水を加熱する給水加熱器を備え、
    　前記制御部は、前記給水加熱用ボイラで発生した蒸気の一部を排出する蒸気制御弁、及び／又は、前記給水加熱用ボイラで発生した蒸気に対してスプレイ水を供給するスプレイ水供給手段を制御する制御と、前記給水熱用ボイラによって加熱された給水温度に応じて、前記給水加熱器に供給される蒸気の抽気量を制御する制御とを比較し、前記給水加熱用熱交換器で加熱された前記給水の温度が低い方の制御を選択する請求項１又は２に記載の発電プラント。     A feed water heater for heating the feed water with steam extracted from the steam turbine;
    The control unit includes a steam control valve that discharges a part of the steam generated in the feed water heating boiler, and / or spray water supply means that supplies spray water to the steam generated in the feed water heating boiler. The control to be controlled is compared with the control to control the extraction amount of the steam supplied to the feed water heater according to the feed water temperature heated by the feed water heat boiler, and is heated by the feed water heating heat exchanger. The power plant according to claim 1 or 2, wherein the control with the lower temperature of the supplied water is selected.
  6. 　前記制御部は、前記蒸気タービンのタービン翼の強度に基づいて、前記蒸気の抽気量を制御する請求項１から５のいずれかに記載の発電プラント。 The power plant according to any one of claims 1 to 5, wherein the control unit controls the amount of steam extracted based on the strength of a turbine blade of the steam turbine.
  7. 　前記過熱器から供給される過熱蒸気の温度を制御する過熱器スプレイを備え、
    　前記制御部は、前記加熱量の変化量に基づいて前記過熱器スプレイのスプレイ量を制御する請求項１から６のいずれかに記載の発電プラント。     Comprising a superheater spray for controlling the temperature of superheated steam supplied from the superheater,
    The said control part is a power plant in any one of Claim 1 to 6 which controls the spray amount of the said superheater spray based on the variation | change_quantity of the said heating amount.
  8. 　前記制御は、前記エコノマイザの出口水温度が飽和温度未満でかつ該飽和温度に近い温度となるように前記加熱量を制御する請求項１から７のいずれかに記載の発電プラント。 The power plant according to any one of claims 1 to 7, wherein in the control, the heating amount is controlled so that an outlet water temperature of the economizer is less than a saturation temperature and close to the saturation temperature.
  9. 　前記ボイラから排出される排ガスを処理する排ガス処理装置を備え、
    　前記制御部は、前記排ガス処理装置に供給される排ガスの上限温度未満でかつ該上限温度に近い温度となるように前記加熱量を制御する請求項１から８のいずれかに記載の発電プラント。     An exhaust gas treatment device for treating the exhaust gas discharged from the boiler;
    The power plant according to any one of claims 1 to 8, wherein the control unit controls the heating amount so that the temperature is less than an upper limit temperature of exhaust gas supplied to the exhaust gas treatment device and is close to the upper limit temperature.
  10. 　前記給水加熱用ボイラは、バイオマス燃料を主燃料として用いるバイオマスボイラとされている請求項１から９のいずれかに記載の発電プラント。 The power plant according to any one of claims 1 to 9, wherein the feed water heating boiler is a biomass boiler using biomass fuel as a main fuel.
  11. 　エコノマイザ及び過熱器を有するボイラと、
    　該ボイラにて生成された蒸気によって駆動される蒸気タービンと、
    　該蒸気タービンによって駆動される発電機と、
    　前記ボイラに供給される給水を加熱する給水加熱用ボイラと、
    　前記給水加熱用ボイラで発生した加熱流体と前記ボイラへ供給される前記給水とを熱交換する給水加熱用熱交換器と、
    を備えた発電プラントの運転方法であって、
    　前記給水加熱用ボイラが前記給水を加熱する加熱量を制御する発電プラントの運転方法。     A boiler having an economizer and a superheater;
    A steam turbine driven by steam generated in the boiler;
    A generator driven by the steam turbine;
    A feed water heating boiler for heating feed water supplied to the boiler;
    A feed water heating heat exchanger that exchanges heat between the heating fluid generated in the feed water heating boiler and the feed water supplied to the boiler;
    A power plant operating method comprising:
    A method for operating a power plant, wherein the feed water heating boiler controls a heating amount for heating the feed water.
PCT/JP2018/015593 2017-04-28 2018-04-13 Power generation plant and operation method therefor WO2018198836A1 (en)

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