JP6549342B1 - POWER PLANT AND ITS OPERATION METHOD - Google Patents

Abstract

A power plant including a feed water heating boiler that can be started at low cost is provided. SOLUTION: At least a part of feed water supplied to a boiler 3 via a deaerator 53 is connected to a biomass boiler feed water pipe 80 connected so as to be able to supply the biomass boiler 7, and connected to the biomass boiler feed water pipe 80. A boiler starting feed water pump 70 and a biomass boiler starting control valve 80 a provided in the biomass boiler feed water pipe 80 are provided. When the biomass boiler 7 is started, the control unit 30 starts the boiler start feed water pump 70 and opens the biomass boiler start control valve 80a. When the start of the biomass boiler 7 is completed, the control unit 30 sets the biomass boiler start control valve 80a. Closed. [Selection] Figure 1

Description

  The present invention relates to a power plant including a feed water heating boiler for heating boiler feed water, and an operation method thereof.

  Patent Document 1 discloses a power generation plant capable of improving turbine efficiency and reducing the amount of carbon dioxide generated by heating boiler feed water with a biomass boiler.

Patent No. 6224858

The power plant described in Patent Document 1 is provided with a feedwater heating pump for returning condensed water condensed by heat exchange with a feedwater heating heat exchanger to a biomass boiler.
When starting a biomass boiler, it is necessary to pressurize water to, for example, 10 MPa using a feedwater heating pump, for example. Moreover, in consideration of returning the condensed water after heat exchange, it is necessary to have heat resistance of 200 ° C. or more. As described above, a pump having a high lift from atmospheric pressure to about 10 MPa and having heat resistance has a problem of increased cost as equipment.

  This invention is made in view of such a situation, Comprising: It aims at providing the electric power generating plant provided with the boiler for feedwater heating which can be started at low cost, and its operating method.

  A power plant according to one aspect of the present invention heats a boiler, a steam turbine driven by steam generated by the boiler, a generator driven by the steam turbine, and feed water supplied to the boiler A feed water heating boiler, a feed water heating heat exchanger for exchanging heat between the steam generated by the feed water heating boiler and the feed water supplied to the boiler, the feed water heating heat exchanger, and the feed water heating boiler A feed water heating pump provided between the feed water heating boiler and a feed water heating boiler water supply pipe connected so as to be able to supply to the feed water heating boiler at least a part of the feed water supplied to the boiler via the deaerator A start-up water supply pump connected to the water supply heating boiler water supply pipe, a start-up control valve provided on the water supply heating boiler water supply pipe, and a start time of the water supply heating boiler The said starting control valve while starting the starting feed water pump is opened, and includes a control unit for the activation control valve is closed during startup completion of the water supply heating boiler.

In addition to the feedwater heating pump provided between the feedwater heating heat exchanger and the feedwater heating boiler, a starting feedwater pump is provided. The feed water connected to the boiler for feed water heating so that it can be fed to at least a part of the feed water supplied to the boiler via the deaerator and pressurized by the feed water pump for startup is the boiler feed water piping for feed water heating. It is supplied to the feed water heating boiler via That is, when the feed water heating boiler is started, the start control valve is opened by the control unit, and the feed water pressurized to a predetermined pressure is supplied to the feed water heating boiler. On the other hand, when the start of the feed water heating boiler is completed, the start control valve is closed to stop the water supply to the feed water heating boiler.
As described above, since the feed water pump can be pressurized to a predetermined pressure by the start feed water pump without setting the feed water heating pump that is required to have heat resistance during normal operation at the start of the biomass boiler to a specification of high lift, It can be started at cost.

  Furthermore, in the power plant according to one aspect of the present invention, the start-up water supply pump is a boiler start-up water supply pump used when starting the boiler.

In order to pressurize the boiler feed water when the boiler is started, a feed water pump for starting the boiler is often provided. Since this boiler start-up water supply pump is paused after the boiler start-up, the boiler start-up water supply pump is used as a start-up water supply pump for boosting the water supply when starting up the water supply heating boiler. As a result, the existing equipment can be effectively used to reduce the equipment cost and start up at low cost.
Since the existing feed water pump for starting the boiler is used, the feed water of the stable water quality boiler supplied to the boiler via the deaerator can be guided to the feed water heating boiler. Thereby, the water supply of the stable water quality used by the boiler can be used for the boiler for feedwater heating.

  Furthermore, in the power generation plant according to one aspect of the present invention, the steam generation pipe for heating which guides the steam generated in the boiler for water supply heating to the heat exchanger for water supply heating, and the steam supply pipe for heating are connected. The control unit includes a start-up discharge pipe whose side opens to the outside of the system and a drain valve provided on the start-up discharge pipe, and the control unit performs the drain valve for a first predetermined time when the feed water heating boiler is started. Open.

  By connecting the start-up discharge pipe to the heating steam supply pipe, it is possible to discharge the feed water passing through the feed water heating boiler at the time of start-up to the outside of the system. The control unit is configured to open the drain valve for a predetermined time when the feed water heating boiler is started. As a result, it is possible to discharge the feed water that does not satisfy the predetermined water quality standard that occurs when passing through the feed water heating boiler at the time of start-up to the outside of the system by adding a simple start-up discharge pipe. Can be launched.

  Furthermore, in the power plant according to one aspect of the present invention, a condenser to which the steam expanded by the steam turbine is introduced, and a start-up circulation pipe connecting the condenser and the start-up discharge pipe The control unit switches the flow of the water supply flowing through the start-up discharge pipe from discharging out of the system to the condenser after the first predetermined time has elapsed.

  After the first predetermined time has elapsed, the feed water flowing through the start discharge pipe can be flowed to the condenser by the start circulation pipe. As a result, it is possible to guide the water supply with stable water quality to the boiler through the condenser, and it is possible to suppress the usage amount of the water supply as much as possible by avoiding discharging the water supply out of the system. , Can be launched at low cost.

  Furthermore, in the power plant according to one aspect of the present invention, a condenser to which the steam expanded by the steam turbine is introduced, and the feed water passing through the feed water heating heat exchanger are led to the condenser side. A feed water return system, and the control unit supplies the feed water to the condenser using the feed water return system when the feed water heating boiler is started.

By supplying the condenser side with the feedwater that has passed through the feedwater heating heat exchanger at the startup time and feeding it to the condenser side, the sensible heat of the feedwater is effectively used by the boiler to feed water to the boiler It is possible to suppress the decrease in the water supply temperature.
The feed water introduced by the feed water return system only needs to be supplied to the condenser, and not only means that the feed water is directly led to the condenser, but, for example, after passing through other equipment, You may be led.

  Furthermore, in the power plant according to one aspect of the present invention, a feed water heater for extracting steam from the steam turbine to heat the feed water, and drain water obtained by heating the feed water by the feed water heater are recovered. A drain water system leading to a water tank, and the water supply return system is connected to the drain water system.

  By introducing the feedwater heated by the feedwater heating heat exchanger to the drain water system of the feedwater heater, the amount of heating of the feedwater heater to the feedwater can be increased.

  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 a main fuel.

  By setting the boiler for feed water heating as a biomass boiler using biomass fuel as a main fuel, it is possible to burn off the biomass fuel in the feed water heating boiler without mixing the biomass fuel in the boiler. Therefore, the use ratio of biomass fuel to, for example, fossil fuel to be burned by the boiler can be increased. In addition, inexpensive biomass fuel containing a corrosive component can be used without affecting combustion in the boiler main body, the amount of fossil fuel used can be reduced, and highly efficient power generation can be performed.

  Further, according to one aspect of the present invention, there is provided a method of operating a power plant, comprising: supplying a boiler, a steam turbine driven by steam generated by the boiler, a generator driven by the steam turbine, and the boiler A feed water heating boiler for heating the feed water, a feed water heating heat exchanger for exchanging heat between the steam generated by the feed water heating boiler and the feed water supplied to the boiler, and the feed water heating heat exchanger A feed water heating pump for introducing condensed water, which exchanges heat with feed water and condenses, to the feed water heating boiler, and at least a portion of the feed water supplied to the boiler via the deaerator to the feed water heating boiler A feed water heating boiler water supply pipe connected so as to be able to be supplied, a starting water supply pump connected to the water supply heating boiler water supply pipe, and an origin provided in the water supply heating boiler water supply pipe Method of operating a power generation plant comprising a control valve, wherein the start-up water supply pump is started and the start-up control valve is opened when the water supply heating boiler is started, and the water supply heating The start control valve is closed when the start of the boiler is completed.

  Furthermore, in the method of operating a power plant according to one aspect of the present invention, the power plant includes a condenser to which the steam expanded by the steam turbine is introduced, and the feedwater that has passed through the feedwater heating heat exchanger. A feed water return system leading to the condenser side, and the feed water is supplied to the condenser side using the feed water return system when the feed water heating boiler is started.

  Since the start-up feed water pump is provided separately from the feed water heating pump, it is possible to start the power plant equipped with the feed water heating boiler at low cost.

It is a schematic block diagram showing a first embodiment of a power plant of the present invention. It is the flowchart which showed the starting method of the biomass boiler. It is the schematic block diagram which showed the state which discharges the water supply from a biomass boiler out of the system at the time of starting of a biomass boiler. It is the schematic block diagram which showed the state which returns the feedwater from a biomass boiler to a condenser at the time of starting of a biomass boiler. It is the schematic block diagram which showed the state which returns the water supply from a water supply return piping to drain water system at the time of starting of a biomass boiler. It is the schematic block diagram which showed the state switched to the water supply return piping from the discharge pipe at the time of starting at the time of starting of a biomass boiler. It is the schematic block diagram which showed the state after start-up of the biomass boiler. It is a schematic block diagram showing a second embodiment of a power plant of the present invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
First Embodiment
The power plant 1 according to the first embodiment is shown in FIG. The power plant 1 includes a boiler 3, a steam turbine 5, and a biomass boiler (a boiler for feed water heating) 7.

  The boiler 3 is equipped with the burner 11 which forms a flame using fossil fuels, such as coal and oil, in the furnace 10 of the boiler main body 3a. The furnace wall forming the furnace 10 is a water-cooled wall 12 constituted by heat transfer tubes and fins, and the water heated by the water-cooled wall 12 is led to the steam drum 15. A water drum 14 is provided vertically below the water cooling wall 12. The water in the steam drum 15 is led to the water drum 14 by the circulation pump 20, and the water is supplied to the water cooling wall 12. In addition, although the subcritical pressure boiler which has a drum is made into an example in this embodiment, it is applicable also to the supercritical pressure boiler which does not have a drum.

  The flue gas generated by the flame of the burner 11 flows vertically upward of the furnace 10 and is led to the superheater 13. The reheater 17 and the economizer 18 are provided in this order on the downstream side of the flue gas flow of the superheater 13.

  Between the economizer 18 and the steam drum 15, an economizer outlet pipe 22 through which water after being heated by the economizer 18 flows 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 the 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. The feed water passing through the feed water pipe 24 is supplied to the economizer 18 after being heated by the steam generated by the biomass boiler 7 as described later. The water supply pipe 24 on the inlet side of the economizer 18 is provided with a temperature sensor 58T. The measured value of the temperature sensor 58T is sent to the control unit 30.

  A flue gas temperature sensor 25T for measuring the temperature of the flue gas after passing through the economizer 18 is provided on the downstream side of the flue gas flow downstream of 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 conducted to a denitration device (not shown) provided at an intermediate position of the exhaust gas duct connected to the boiler main body 3a for removing NOx in the combustion gas. It is eaten.

  The denitration apparatus is a selective catalytic reduction denitration apparatus using ammonia, and the upper limit temperature (for example, about 400 ° C. to about 420 ° C.) is determined in relation to the catalytic reaction temperature. Therefore, based on the temperature of the combustion exhaust gas temperature sensor 25T, the temperature of the combustion exhaust gas is controlled by adjusting the amount of heat exchange in the boiler 3 by the control unit 30 so as not to exceed the upper limit temperature of the NOx removal device. The flue gas passing through the denitrification apparatus is, for example, a dust processing apparatus, induction fan not shown on the downstream side after SOx and the like are removed by a desulfurization apparatus (not shown) to remove SOx in combustion gas. Are provided as needed, and are discharged to the atmosphere from a chimney at the downstream end of the exhaust gas duct.

  The heater 13 is provided with a heater 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 predetermined temperature range. The water used in the superheater spray 27 is, for example, a part of the outlet water of the economizer 18. The water injection amount and injection timing of the superheater spray 27 are controlled by the control unit 30.

  The superheated steam leaving the superheater 13 is led to the steam turbine 5 through the main steam piping 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 by the turbines 34, 35, 36, and power generation is performed.

  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 the steam which has performed a predetermined expansion in the high pressure turbine 34 to rotationally drive the turbine is introduced to the reheater 17. It has become.

  Between the steam outlet side of the reheater 17 and the intermediate pressure turbine 35, a reheated steam supply pipe 40 for supplying reheated steam to the intermediate pressure turbine 35 is provided.

  An 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 the steam which has performed predetermined expansion in the intermediate pressure turbine 35 and rotationally drives the turbine is guided to the low pressure turbine 36 It is supposed to be.

  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 under vacuum by means of a cooling water (not shown) to condense and liquefy. The condensed water liquefied by the condenser 46 becomes feed water and is led to the low pressure feed water heater 50 by the condensate pump 48.

  In the present embodiment, for example, in the low pressure feed water heater 50, the low pressure steam introduced from the low pressure turbine 36 heats the feed water from the condensed water. The feedwater heated by the low pressure feedwater heater 50 is led to the deaerator 53 through the feedwater pump 51. In the deaerator 53, the gas phase component (air, particularly oxygen) is removed from the feed water using medium pressure steam, and a predetermined water quality is stably ensured.

  The feed water deaerated by the deaerator 53 is led to the first medium pressure feed water heater 52 a and heated by the medium pressure steam extracted from the medium pressure turbine 35.

Between the deaerator 53 and the first medium-pressure feed water heater 52a, a boiler start-up water supply pipe 69 for circulating the water supply when the boiler 3 is started is provided. The boiler starting water supply pipe 69 is provided with a boiler starting water supply pump 70 and a boiler starting on-off valve 69a. The control unit 30 opens the boiler start on-off valve 69a when the boiler 3 is started, and closes the rest. The boiler start-up water supply pump 70 is driven by the electric motor so as to be operable even without a steam source at start-up, is started at start-up of the boiler 3, and is used to boost water supply from atmospheric pressure. The water pressure to be pressurized is, for example, a predetermined pressure of 10 MPa or more and 15 MPa or less. In the conventional power plant, the feed water pump 70 for starting the boiler is used only at the start of the boiler 3 and is otherwise stopped.
However, in addition to the time of starting of the boiler 3, in this embodiment, it uses also at the time of starting of the biomass boiler 7 so that it may mention later. Therefore, biomass boiler water supply piping (boiler water supply piping for water supply heating) 80 is provided which branches from between the boiler start water supply pump 70 and the boiler start on-off valve 69a and is connected to the biomass boiler 7 on the downstream side. . The biomass boiler feed water pipe 80 is provided with a biomass boiler start control valve (start control valve) 80 a. The opening degree of the biomass boiler start control valve 80 a is controlled by the control unit 30.
The biomass boiler water supply pipe 80 may be provided with a water pump 80 b for auxiliary start. The auxiliary start-up water supply pump 80b is driven by an electric motor, and is additionally installed and used when the existing pump start-up water supply pump 70 is insufficient. Therefore, if the lift head of the start-up water supply pump 70 is sufficiently obtained, the auxiliary start-up water supply pump 80 b can be omitted.

  The feedwater heated by the first medium pressure feedwater heater 52a is led to the first high pressure feedwater heater 54a and the second high pressure feedwater heater 54b.

The high pressure steam led to the first high pressure feed water heater 54a is led via the first high pressure extraction pipe 55a. The first high pressure extraction pipe 55 a is provided with a first high pressure extraction valve 56 a whose opening degree is controlled by the control unit 30.
The high pressure steam led to the second high pressure feed water heater 54b is led via the second high pressure extraction pipe 55b. The second high pressure extraction pipe 55 b is provided with a second high pressure extraction valve 56 b whose opening degree is controlled by the control unit 30.
In the present embodiment, as an example, since the first high pressure extraction pipe 55a is connected to the upstream side (high pressure side) of the high pressure turbine 34 than the second high pressure extraction pipe 55b, the first high pressure extraction pipe 55a The pressure of the high pressure steam to be discharged is higher than the pressure of the high pressure steam led by the second high pressure extraction pipe 55b.

  The steam after heating the feed water by each feed water heater 50, 52a, 52b, 54a, 54b becomes drain water, and as shown in FIG. 1, through the drain water system (condensed water supply system) 59, sequentially It is sent to the feed water heaters 50, 52a, 54a, 54b of the low pressure stage, and finally collected by the condenser 46.

  The feed water heated by the high-pressure feed water heaters 54 a and 54 b passes through the feed water pipe 24 and is led to the feed water heating heat exchanger 60. In the feed water heating heat exchanger 60, the feed water is heated by the steam led from the biomass boiler 7 to the heating heat transfer pipe 61. Between the biomass boiler 7 and the feed water heating heat exchanger 60, condensation occurs after heat exchange between the heating steam supply pipe 62 for supplying steam to the heating heat transfer pipe 61 and the heating heat transfer pipe 61 A return pipe 64 for returning water to the biomass boiler 7 and a return pump (a pump for supplying water) 65 are provided.

  The heating steam supply pipe 62 includes a heating steam temperature sensor 62T for measuring the temperature of the heating steam, a heating steam pressure sensor 62P for measuring the pressure of the heating steam, and a heating for measuring the flow rate of the heating steam. Steam flow sensor 62F is provided. The measured values of the sensors 62T, 62P, 62F are sent to the control unit 30.

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 circulated between the biomass boiler 7 and the heat exchanger 60 for feed water heating. It has become. The operation of the return pump 65 is driven by an electric motor and controlled by the control unit 30.
The start-up operation valve 73 is provided in the return pipe 64 between the return pump 65 and the biomass boiler 7. The start-up operation valve 73 is an open / close valve, and is controlled by the control unit 30.

  A feed water bypass pipe 67 is provided 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. The water supply pipe 24 on the upstream side of the water supply bypass pipe 67 is provided with a temperature sensor 57T that measures the temperature of the heat exchanger inlet for water supply heating. The measured value of the temperature sensor 57T is sent to the control unit 30.

A water supply return pipe (condensed water supply system) 71 is branched from the return pipe 64 between the downstream side of the heating heat transfer pipe 61 and the upstream side of the return pump 65. The downstream side of the water supply return pipe 71 is connected to the drain water system 59. Specifically, the downstream side of the water supply return pipe 71 is connected to the upstream side of the drain water system 59, more specifically, to the outlet of the first high pressure water heater 54a.
A water supply return control valve 72 is provided in the water supply return pipe 71. The opening degree of the water supply return control valve 72 is controlled by the control unit 30.

  The upstream side of the start-up discharge pipe 75 is connected to an intermediate position of the heating steam supply pipe 62. The downstream side of the start-up discharge pipe 75 is open to the outside of the system. Therefore, the steam and the heated water that have flowed through the start-up discharge pipe 75 can be discharged out of the system. The start-up discharge on-off valve 76 and the drain valve 77 are provided in the start-up discharge pipe 75 sequentially from the upstream side. The start-up discharge on-off valve 76 and the drain valve 77 are controlled by the control unit 30. A flush tank 79 is provided between the start-up discharge on-off valve 76 and the drain valve 77. Gas and liquid are separated by the flash tank 79.

  A water quality sensor 75 a is provided in the start-up discharge pipe 75. The output of the water quality sensor 75a is transmitted to the control unit 30. As the water quality sensor 75a, for example, a turbidimeter or an iron densitometer is used.

  A start-up circulation pipe 81 is branched from between the flash tank 79 and the drain valve 77. The downstream side of the start-up circulation pipe 81 is connected to the condenser 46. A startup circulation control valve 83 is provided in the startup circulation pipe 81. The opening degree of the start-up circulation control valve 83 is controlled by the control unit 30.

  The biomass boiler 7 burns biomass fuel to generate steam. The evaporation amount of the biomass boiler 7 in the present embodiment is, for example, 30% or less, preferably 20% or less of that of the boiler 3. The output of the biomass boiler 7 is controlled by the control unit 30. Specifically, the control unit 30 controls the supply amount of biomass fuel, the flow rate of combustion air, the supply amount of generated steam, and the like to be input to the biomass boiler 7. Thus, by controlling the output of the biomass boiler 7 by the control unit 30, the heating amount of the feed water in the feed water heating heat exchanger 60 is controlled.

  The control unit 30 includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a computer readable storage medium, and the like. Then, a series of processes for realizing various functions are stored in the form of a program, for example, in a storage medium or the like in the form of a program, and the CPU reads this program into a RAM etc. Thus, various functions are realized. The program may be installed in advance in a ROM or other storage medium, may be provided as stored in a computer-readable storage medium, or may be distributed via a 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 configured as described above operates as follows.
The superheated steam generated in the superheater 13 of the boiler 3 is led to the high pressure turbine 34 of the steam turbine 5 and is led to the reheater 17 after rotationally driving the high pressure turbine 34. The steam led to the reheater 17 is reheated by the boiler 3 and led to the medium pressure turbine 35 as reheated steam. The reheated steam is led to the low pressure turbine 36 to rotationally drive the low pressure turbine 36 after the intermediate pressure turbine 35 is rotationally driven. The generator 37 is rotationally driven by the rotational power thus obtained, and power generation is performed.

  The steam that has completed the work of rotationally driving the turbine by performing predetermined expansion in the low pressure turbine 36 is condensed in the condenser 46 and sequentially passes through the feed water heaters 50, 52a, 54a, 54b as feed water. It is heated by Thereafter, the feed water is further heated by the feed water heating heat exchanger 60 and is supplied to the economizer 18 of the boiler 3.

<Biomass boiler start control>
Next, start-up control of the biomass boiler 7 will be described with reference to FIG. The following control is performed by the control unit 30.

  As shown in step S1, the biomass boiler 7 is started in a state where the load of the boiler 3 is close to the rated operation. The state close to the rated operation means, for example, 80% to 100% when the rating of the boiler 3 is 100%. The water supply bypass valve 68 is open, and the water supply heating heat exchanger 60 is not supplied with the water supply from the first high-pressure water supply heater 54 a side.

  Then, as shown in step S2, the boiler activation water supply pump 70 is activated to supply the water supply stored in the deaerator 53 to the biomass boiler 7. Thus, the boiler activation water supply pump 70 is used as a biomass boiler activation water supply pump not only when the boiler 3 is activated but also when the biomass boiler 7 is activated. At this time, as shown in FIG. 3A, the biomass boiler start control valve 80a is controlled from closed to open. In the case of a configuration in which a desired head necessary for the biomass boiler 7 can not be obtained by the boiler start-up water supply pump 70, the auxiliary start-up water supply pump 80b is installed and activated simultaneously. The feed water is gradually boosted to a desired pressure (for example, a predetermined pressure of 10 MPa to 15 MPa) by the boiler start-up water supply pump 70.

  In FIG. 3A and later, the valve is shown in black when it is closed and white when it is open. In addition, when fluid (steam or water) flows in the piping, it is indicated by a solid line, and when it is not flowing, it is indicated by a broken line.

The boiler start on-off valve 69a is kept closed. Therefore, water supply to the first medium pressure water heater 52 a is not performed by the boiler start water supply pump 70.
When the biomass boiler 7 is supplied with water, the biomass fuel is charged into the biomass boiler 7 to perform temperature rise and pressure increase. The feed water passing through the biomass boiler 7 passes through the startup discharge pipe 75 while being heated and pressurized, and is led to the flash tank 79 via the startup discharge on-off valve 76. Gas-liquid separation is performed by the flash tank 79, and drain water, which is a liquid phase, is discharged out of the system through the drain valve 77.
The start-up operation valve 73 provided in the return pipe 64 is closed, and the return pump 65 is stopped. The water supply return control valve 72 provided in the water supply return system 71 is also closed. As a result, since the feed water is delivered from the start-up discharge pipe 75, the feed water is not supplied to the heating heat transfer pipe 61, and the feed water of the boiler 3 is not heated in the feed water heating heat exchanger 60.
As described above, in step S2, after the water supply of the boiler 3 extracted from the deaerator 53 is supplied to the biomass boiler 7 using the boiler activation water supply pump 70, it is discharged out of the system.

  If drainage is continued from the start-up discharge piping 75 until the first predetermined time has elapsed, the water quality is improved, and the output indicated by the water quality sensor 75a comes to satisfy the predetermined value. This is because the impurities remaining in the biomass boiler 7 and the piping connected to the biomass boiler 7 at the time of startup are sequentially discharged, and the water quality is gradually improved. Then, the first predetermined time is determined, for example, when the output of the water quality sensor 75a satisfies a predetermined value. For example, if the water quality sensor 75a is a turbidity meter or an iron densitometer, it is judged that the water quality sensor 75a has a predetermined value or less, and the process proceeds to the next step S3.

  In step S3, as shown in FIG. 3B, the drain valve 77 is opened and closed, and the startup circulation control valve 83 is opened and closed. Thereby, the drain water led from the flash tank 79 provided in the start-up discharge pipe 75 is led to the condenser 46 through the start-up circulation pipe 81. Thus, in step S3, after the water supply of the boiler 3 extracted from the deaerator 53 is supplied to the biomass boiler 7 using the water supply pump 70 for boiler activation, it is recovered to the condenser 46 and circulated. It will be. Also during the step S3, the fuel is injected into the biomass boiler 7 and the temperature rise and pressure increase are continuously performed.

  Then, as shown in step S4, it is determined whether the feed water temperature heated by the biomass boiler 7 measured by the heating steam temperature sensor 62T has reached the first predetermined temperature. The first predetermined temperature is set to a temperature equal to the temperature of the feed water flowing into the feed water heating heat exchanger 60 measured by the temperature sensor 57T, and is, for example, 250 ° C. or more and 300 ° C. or less. If the temperature of the water supplied from the biomass boiler 7 does not reach the first predetermined temperature, step S3 is continued, and if the first predetermined temperature is reached, the process proceeds to step S5.

  In step S5, as shown in FIG. 3C, the feed water return control valve 72 is closed and then opened, so that the feed water (heated water) heated by the biomass boiler 7 is transferred from the heating steam supply pipe 62 to the heat exchange for feed water heating. The feed water (heating water) supplied to the heating heat transfer pipe 61 of the vessel 60 and passed through the heating heat transfer pipe 61 is supplied to the drain water system 59 via the water supply return pipe 71. By heating the drain water flowing through the drain water system 59 of each of the feed water heaters 54 b and 52 a by the water supply (heating water), a decrease in the temperature of the water feed supplied to the boiler 3 is suppressed. In addition, if there is a possibility that the operation of the turbines 34, 35, 36 may be affected if the heating water is received from the feed water return pipe 71 due to the restriction of the design capacity of the drain water system 59, the output of the boiler 3 is temporarily May be lowered to receive water (heated water).

  Here, in step S5, the opening degree of the water supply return control valve 72 is gradually increased, and the opening degree of the start-time circulation control valve 83 is gradually closed. Thereby, the destination of the water supply (heating water) used for heating of the biomass boiler 7 is gradually switched from the condenser 46 to the heat exchanger 60 for water supply heating. The switching speed of the feed water return control valve 72 and the start time circulation control valve 83 may be a predetermined value preset in the control unit 30, or the feed water temperature and heating of the boiler 3 measured by the temperature sensor 57T. The controller 30 may control while obtaining the feed water temperature measured by the for-use steam temperature sensor 62T.

  Then, in step S6, it is determined whether the water supply temperature at the inlet of the boiler 3 (economizer 18) measured by the temperature sensor 58T has reached a second predetermined value. The second predetermined value is determined according to the specifications of the boiler 3, but a temperature at which the feed water is not vaporized at the outlet of the economizer 18 is selected, and more preferably the economizer 18 outlet water temperature is less than the saturation temperature and the saturation The temperature is selected to be close to the temperature, for example, an appropriate value of 280 ° C. to 320 ° C. is used.

When the feed water temperature at the inlet of the boiler 3 has not reached the second predetermined value, step S5 is continuously performed, and the temperature rise and pressure increase of the biomass boiler 7 are continuously performed.
When the feed water temperature at the inlet of the boiler 3 reaches the second predetermined value, the process proceeds to step S7.

  In step S7, as shown in FIG. 3D, the startup circulation control valve 83 is closed and the startup discharge on-off valve 76 is closed. Thus, the feed water introduced from the biomass boiler 7 is prevented from being introduced to the condenser 46. At this time, the water supply return control valve 72 remains open. Thus, the destination of the water supplied from the biomass boiler 7 is switched from the condenser 46 to the drain water system 59. At this time, the feed water bypass valve 68 is closed, and the feed water is introduced from the first high pressure feed water heater 54 a side to the feed water heating heat exchanger 60.

  Then, in step S8, as shown in FIG. 3E, the biomass boiler start control valve 80a is gradually closed, and the water supply return control valve 72 is gradually closed. When the water supply return control valve 72 is closed, the boiler start water supply pump 70 is stopped.

  Further, the start-up operation valve 73 is closed and opened, and the return pump 65 is started. Since the pressure has already been raised to a predetermined pressure by the boiler start-up water supply pump 70, the return pump 65 can be started. Thereby, the steam generated in the biomass boiler 7 is sent to the feed water heating heat exchanger 60, and the condensed water condensed in the heating heat transfer pipe 61 is returned to the biomass boiler 7 by the return pump 65. Thus, the circulating water system of the biomass boiler 7 is operated independently from the boiler 3.

  Then, the process proceeds to step S9, the settling operation of the biomass boiler 7 is performed, the operation system of the biomass boiler 7 is established, and the start is completed.

As described above, when the start control is completed, the heating amount of the biomass boiler 7, the amount of 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 steam by the superheater spray 27 The boiler 3, the biomass boiler 7 and the steam turbine 5 are operated appropriately according to the load of the power plant 1 by controlling the temperature of the
The heating amount of the biomass boiler 7 is controlled based on the economizer outlet temperature sensor 22T and control based on the combustion exhaust gas temperature sensor 25T from the heating steam temperature sensor 62T, the heating steam pressure sensor 62P, and the heating steam flow rate sensor 62F. Is controlled by the control unit 30 so as to satisfy both of the above.

According to the present embodiment, the following effects are achieved.
Aside from the return pump 65, the boiler start water supply pump 70 is used at the start of the biomass boiler 7. The feed water connected to the biomass boiler 7 so as to be able to be supplied to the biomass boiler 7 for at least a part of the feed water supplied to the boiler 3 via the deaerator 53 and pressurized by the feed water pump 70 for starting the boiler It is supplied to the biomass boiler 7 via 80. That is, when the biomass boiler 7 starts up, the control unit 30 opens the control valve 80 a for biomass boiler activation, and the feed water pressurized to a predetermined pressure is supplied to the biomass boiler 7. On the other hand, when the start of the biomass boiler 7 is completed, the biomass boiler start control valve 80a is closed, and the water supply to the biomass boiler 7 is stopped.
As described above, the feed water can be pressurized to a predetermined pressure by the boiler start water supply pump 70 without setting the return pump 65 requiring heat resistance during normal operation to the high lift specification at the start of the biomass boiler 7. , Can be launched at low cost.

In order to pressurize the boiler feed water when the boiler 3 is started, a boiler start water supply pump 70 is provided. Since the boiler start-up feed water pump 70 is stopped after the start of the boiler 3, the boiler start-up feed water pump 70 is used as a start-up feed water pump for boosting the water supply when starting up the biomass boiler 7. . As a result, the existing equipment can be effectively used to reduce the equipment cost and start up at low cost.
Since the existing boiler start-up water supply pump 70 is used, the water supply of the boiler 3 of stable water quality supplied to the boiler 3 via the deaerator 53 can be guided to the biomass boiler 7. Thereby, the water supply of the stable water quality used by the boiler 3 can be used for the biomass boiler 7.

  By connecting the start-up discharge pipe 75 to the heating steam supply pipe 62, the feed water passing through the biomass boiler 7 can be discharged out of the system at the time of start-up. The control unit 30 opens the drain valve 77 for a predetermined time when the biomass boiler 7 is started. As a result, it is possible to discharge the water supply that does not meet the predetermined water quality standard that occurs when passing through the biomass boiler 7 at the time of start-up to the outside of the system by adding a simple start-up discharge pipe, so starting at low cost can do.

  After the first predetermined time has elapsed, the feed water flowing through the start discharge pipe 75 can be flowed to the condenser 46 by the start circulation pipe 81. As a result, the water supply with stable water quality can be guided to the boiler 3 through the condenser 46, and the amount of water used can be reduced as much as possible by avoiding discharging the water supply out of the system. Since it can, it can start at low cost.

  The feed water passing through the feed water heating heat exchanger 60 at the time of start-up is supplied to the drain water system 59 via the feed water return pipe 71 without being circulated to the biomass boiler 7, so the sensible heat of the feed water is It is possible to suppress the decrease in the temperature of the water supplied to the boiler 3 by effectively using the

Second Embodiment
Next, a second embodiment of the present invention will be described using FIG. The present embodiment is different in that the feed water of the biomass boiler 7 is not boosted by the feed water pump 70 for boiler activation used in the first embodiment. Since the second embodiment is the same as the first embodiment in the other points, the same components are denoted by the same reference numerals and the description thereof will be omitted.

  As shown in FIG. 4, the biomass boiler feed water pipe (feed water heating feed water pipe) 80 ′ has a biomass boiler start control valve 80 a and a biomass boiler start feed water pump 88 (hereinafter simply referred to as “start feed water pump 88 ") Is provided. The start-up water supply pump 88 is driven by an electric motor and is controlled by the control unit 30.

  A biomass boiler deaerator 90 is provided between the startup feed water pump 88 and the biomass boiler startup control valve 80a. For example, utility steam in the power plant 1 is used as a heat source of the biomass boiler deaerator 90.

  A pure water supply source (not shown) is connected to the upstream side of the biomass boiler water supply pipe 80 '. The pure water supplied from the pure water supply source is controlled by the pure water supply valve 80c. A biomass boiler condensate tank 92 is provided between the pure water supply valve 80 c and the start-up water supply pump 88. A connection pipe 94 for circulation is provided in the condensate tank 92 for biomass boiler between the start-up discharge pipe 75. The circulation connection pipe 94 is provided with a circulation control valve 94a. The control valve for circulation 94 a is controlled by the control unit 30.

  The downstream end of the startup circulation pipe 81 is connected between the biomass boiler condensing tank 92 and the pure water supply valve 80c.

In the present embodiment, with the above configuration, the same activation control as that of the first embodiment is performed.
That is, when starting the biomass boiler 7, the pure water supply valve 80c and the biomass boiler start control valve 80a are opened to start the feed water supply pump 88 so as to correspond to step S2 in FIG. Supply to 7. Thus, in the present embodiment, the pressurization of the water supply to the biomass boiler 7 is performed by the start-up water supply pump 88. The feed water passing through the biomass boiler 7 is discharged out of the system via the start-up discharge pipe 75. At this time, the drain valve 77 is open, and the circulation control valve 94a is closed.

  Then, when stability of the water quality is confirmed by the water quality sensor 75a after the first predetermined time, the pure water supply valve 80c is closed and the drainage valve 77 is closed, and the circulation control valve 94a is opened. . Thus, a circulation system via the circulation connection pipe 94 is formed. This embodiment differs from step S3 in FIG. 2 in that the feed water heated by the biomass boiler 7 is returned to the biomass boiler feed pipe 80 and circulated without returning to the condenser 46.

  When the temperature rise and pressure increase of the biomass boiler 7 progresses and the feed water temperature heated by the biomass boiler 7 reaches the first predetermined temperature as in step S4 of FIG. 2, the feed water return control valve 72 is gradually opened and started up. When the circulation control valve 83 is opened, water is introduced through the condenser 46. At this time, the circulation control valve 94a is gradually closed.

  Thereafter, the circulation control valve 94a and the start-up discharge on-off valve 76 are closed to switch the circulation path to the water supply return pipe 71. As a result, the feed water heated by the biomass boiler 7 is circulated through the feed water return pipe 71, the drain water system 59, the condenser 46, the startup circulation pipe 81, and the biomass boiler water supply pipe 80 '.

  Then, when the feed water at the inlet of the boiler 3 reaches a second predetermined value as in step S6 of FIG. 2 along with the temperature rise of the biomass boiler 7, the feed water return control valve 72 is closed to operate the biomass boiler 7 independently. Do. The subsequent steps are the same as in the first embodiment.

  Thus, according to the second embodiment, the start-up water supply pump 88 is provided separately from the boiler start-up water supply pump 70. Then, the biomass boiler 7 is started using pure water from a pure water supply source outside the boiler 3. Thus, part of the startup operation can be performed independently of the boiler 3. Further, as in the first embodiment, it is possible to start up at low cost.

In addition, in each embodiment mentioned above, although it decided to use the biomass boiler 7 as an additional steam generation apparatus which heats water supply, it is not necessary to necessarily use biomass for a fuel. As the fuel, for example, refuse or combustible waste can be used.
In addition, although the feed water heating heat exchanger 60 is disposed in series with the feed water heaters 50, 52a, 54a, 54b, the heat exchanger 60 is at least one of the feed water heaters 50, 52a, 54a, 54b. It may be arranged in parallel.
Further, the drain water system 59 may be bypassed and connected to the condenser 46 on the downstream side of the water supply return pipe 71.

1 power generation plant 3 boiler 3a boiler main body 5 steam turbine 7 biomass boiler (boiler for feed water heating)
DESCRIPTION OF SYMBOLS 10 Fire furnace 11 Burner 12 Water cooling wall 13 Superheater 15 Steam drum 17 Reheater 18 Economizer 20 Circulation 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 Part 32 Main steam piping 34 High pressure turbine 35 Medium pressure turbine 36 Low pressure turbine 37 Generator 38 High pressure turbine outlet piping 40 Reheated steam supply piping 42 Medium pressure turbine outlet piping 44 Low pressure turbine outlet piping 46 Condenser 48 Condensing water pump 50 Low pressure Water supply heater 51 Water supply pump 52a 1st medium pressure water supply heater 53 Deaerator 54a 1st high pressure water supply heater 54b 2nd high pressure water supply heater 55a 1st high pressure extraction piping 55b 2nd high pressure extraction piping 56a 1st high pressure extraction valve 56b 2nd high pressure extraction valve 57T temperature Sensor 58T Temperature sensor 59 Drain water system (condensed water supply system)
60 feed water heating heat exchanger 61 heating heat transfer pipe 62 heating steam supply piping 62T heating steam temperature sensor 62P heating steam pressure sensor 62F heating steam flow rate sensor 64 return piping 65 return pump (water supply heating pump)
67 Water supply bypass piping 68 Water supply bypass valve 69 Boiler start water supply piping 69a Boiler start on-off valve 70 Boiler start water supply pump (Start-up water supply pump)
71 Water supply return piping (water supply return system)
72 water supply return control valve 73 start-up operation valve 75 start-up discharge piping 75a water quality sensor 76 start-up discharge on-off valve 77 drain valve 79 flush tank 80 biomass boiler water supply piping (boiler water supply piping for water supply heating)
80a Biomass boiler start control valve (start control valve)
80b Auxiliary start-up water supply pump 80c Pure water supply valve 81 Start-up circulation piping 83 Start-up circulation control valve 88 Biomass boiler start-up water supply pump (Start-up water supply pump)
90 Deaerator for biomass boiler 92 Condenser tank for biomass boiler 94 Connection pipe for circulation 94a Control valve for circulation

Claims (9)

A boiler,
A steam turbine driven by steam generated by the boiler;
A generator driven by the steam turbine;
A feed water heating boiler for heating feed water supplied to the boiler;
A heat exchanger for feedwater heating which exchanges heat between the steam generated by the feedwater heating boiler and the feedwater supplied to the boiler;
A feedwater heating pump provided between the feedwater heating heat exchanger and the feedwater heating boiler;
A feed water heating boiler water supply pipe in which at least a part of the water supply supplied to the boiler via a deaerator is connected to the water supply heating boiler so as to be able to be supplied;
A starting feed water pump connected to the feed water heating boiler feed water pipe;
A start control valve provided in the feed water heating boiler feed water pipe;
A control unit for starting the feed water pump for start and opening the control valve for start and for closing the control valve for start of feed water heating when the feed water heating boiler is started; ,
Power plant equipped with.   The power generation plant according to claim 1, wherein the start-up water supply pump is a boiler start-up water supply pump used when starting the boiler. A heating steam supply pipe for guiding the steam generated by the feed water heating boiler to the feed water heating heat exchanger;
Start-up discharge piping connected to the heating steam supply piping, the outlet side of which opens to the outside of the system;
A drain valve provided in the start-up discharge pipe;
Equipped with
The power generation plant according to claim 1 or 2, wherein the control unit opens the drain valve for a first predetermined time when the feed water heating boiler is activated. A condenser through which the steam expanded by the steam turbine is introduced;
Start-up circulation pipe connecting the condenser and the start-up discharge pipe;
Equipped with
The power generation plant according to claim 3, wherein the control unit switches the flow of the feed water flowing through the start-up discharge pipe from the discharge out of the system to the condenser after the first predetermined time passes. A condenser through which the steam expanded by the steam turbine is introduced;
A feed water return system for guiding the feed water passing through the feed water heating heat exchanger to the condenser side;
Equipped with
The power generation plant according to any one of claims 1 to 4, wherein the control unit supplies the feedwater to the condenser side using the feedwater return system when the feedwater heating boiler is started. A feed water heater for extracting steam from the steam turbine to heat the feed water;
A drain water system for guiding drain water condensed by heating the feed water with the feed water heater to the condenser;
Equipped with
The power plant according to claim 5, wherein the feed water return system is connected to the drain water system.   The power plant according to any one of claims 1 to 6, wherein the feed water heating boiler is a biomass boiler using biomass fuel as a main fuel. A boiler,
A steam turbine driven by steam generated by the boiler;
A generator driven by the steam turbine;
A feed water heating boiler for heating feed water supplied to the boiler;
A heat exchanger for feedwater heating which exchanges heat between the steam generated by the feedwater heating boiler and the feedwater supplied to the boiler;
A feedwater heating pump provided between the feedwater heating heat exchanger and the feedwater heating boiler;
A feed water heating boiler water supply pipe in which at least a part of the water supply supplied to the boiler via a deaerator is connected to the water supply heating boiler so as to be able to be supplied;
A starting feed water pump connected to the feed water heating boiler feed water pipe;
A start control valve provided in the feed water heating boiler feed water pipe;
A method of operating a power plant comprising
A power plant for starting the feed water pump for start and opening the control valve for start and for closing the control valve for start of feed water heating when the feed water heating boiler is started. how to drive. The power generation plant includes a condenser to which the steam expanded by the steam turbine is introduced, and a feed water return system that leads the feed water passing through the feed water heating heat exchanger to the condenser side. ,
The method according to claim 8, wherein the feed water is supplied to the condenser by using the feed water return system when the feed water heating boiler is started.

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