WO2021131345A1 - Water treatment device and power generation plant, and water treatment method - Google Patents

Abstract

Provided is a water treatment device equipped with a filtration device that removes iron, with lower capacity and reduced heat loss. The present invention comprises: a filtration device (22) that removes iron from the condensate led from a condenser (20) and also removes iron from the drain water led from a low-pressure feedwater heater (44); and a switching means for selectively switching between the flow of condensate from the condenser (20) to the filtration device (22) and the flow of drain water from the low-pressure feedwater heater (44) to the filtration device (22). The capacity of the filtration device (22) is determined on the basis of the maximum value of the required filtration flow rate of the condensate.

Description

Water treatment equipment and power plants and water treatment methods

This disclosure relates to water treatment equipment, power plants, and water treatment methods.

Large boilers such as coal-fired boilers have a hollow furnace that is installed in the vertical direction, and a plurality of combustion burners are arranged along the circumferential direction of the furnace on the furnace wall. In the coal-fired boiler, a flue is connected above the vertical direction of the furnace, and a heat exchanger for generating steam is arranged in this flue. Then, the combustion burner injects a mixture of fuel and air (oxidizing gas) into the furnace to form a flame, and combustion gas is generated and flows into the flue. A heat exchanger is installed in the area where the combustion gas flows, and superheated steam is generated by heating the water or steam flowing in the heat transfer tube constituting the heat exchanger.

The superheated steam generated by the boiler is supplied to the steam turbine and drives the steam turbine to rotate. Then, power is generated by a generator connected to the steam turbine.

The steam used to drive the steam turbine is sent to the condenser and cooled in the condenser to be condensed. In the boiler water supply system, the condensate used as water supply is heated by a low-pressure water supply heater and a high-pressure water supply heater using the extracted air from the steam turbine, and is supplied to the boiler economizer. The water supply further heated by the economizer is supplied to the evaporation pipes arranged on the furnace wall.

Of the boiler water supply system, iron eluted from the carbon steel part of the low pressure water supply heater drain system flows into the evaporation pipe together with the boiler water supply, and a scale (powder scale) with low thermal conductivity adheres to the inner surface of the evaporation pipe. May accumulate. In that case, the metal temperature of the evaporation tube rises and is damaged, and the boiler water may leak.

In a once-through boiler, the iron concentration in the boiler inlet water supply is specified to be below a predetermined value (for example, in the JIS standard, it is 5 ppb or less during rated load operation). Therefore, a condensate filtration device is installed on the downstream side of the condenser to remove iron in the condensate and keep it below a predetermined control value (Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-245833

In Patent Document 1, both the drain water from the water supply heater and the condensate water are treated by the condensate filtration device. In this case, it is necessary to prepare a large-capacity condensate filtration device corresponding to the total flow rate of the condensate and the drain water from the water supply heater, which may increase the cost.

The drain water from the water supply heater has a temperature of, for example, room temperature or higher (for example, about 80 ° C.), and has a calorific value that can be effectively used in a power plant. However, in Patent Document 1, since the condensate at room temperature is mixed with the drain water from the water supply heater, there is a problem that heat loss occurs.

The present disclosure has been made in view of such circumstances, and is a water treatment device and a power plant equipped with a filtration device for removing iron, which can reduce the capacity and suppress heat loss, and water. The purpose is to provide a processing method.

In order to solve the above problems, the water treatment apparatus according to one aspect of the present disclosure removes iron from the condensate derived from the condenser and drain water derived from the water supply heater that heats the condensate. A filtering device for removing iron from the water, a switching means for selectively switching between a flow of the condensate from the condenser to the filtration device and a flow of drain water from the water supply heater to the filtration device. And have.

The power plant according to one aspect of the present disclosure includes a filtration device that removes iron from the condensate guided from the condenser and removes iron from the drain water guided from the water supply heater, and the condensate is the condensate. A water treatment device including a switching means for selectively switching between a flow from the water device to the filtration device and a flow of the drain water from the water supply heater to the filtration device, and from the water treatment device. It includes a boiler that generates steam from the supplied condensate, and a power generation unit that generates steam using the steam generated by the boiler.

The water treatment method according to one aspect of the present disclosure is a water treatment method using a filtration device that removes iron from the condensate derived from the condenser and removes iron from the drain water guided from the water supply heater. Therefore, the flow of the condensate from the condenser to the filtration device and the flow of the drain water from the water supply heater to the filtration device are selectively switched.

Since it was decided to selectively guide the condensate and drain water to the filtration device, the capacity of the filtration device can be reduced and the heat loss can be reduced.

It is a schematic block diagram which showed the power plant which concerns on one Embodiment of this disclosure. It is a schematic block diagram which showed the circumference of the filtration apparatus of FIG. It is a figure which showed the process of the water treatment of this disclosure. It is a schematic block diagram which showed the state which condensed water is passed through a filtration device at the time of starting a power plant. It is a schematic block diagram which showed the state which drain water is passed through a filtration apparatus at the time of operation of a power plant.

Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the drawings with reference to the accompanying drawings. It should be noted that the present disclosure is not limited by this embodiment, and when there are a plurality of embodiments, the present embodiment also includes a combination of the respective embodiments.

FIG. 1 shows the power plant 1 according to the present embodiment. The power plant 1 includes, for example, a boiler 10 that uses coal as fuel, steam turbines 111 and 113 that are rotationally driven by steam generated by the boiler 10, and a generator 80.

The boiler 10 is a once-through boiler, and pulverized coal obtained by crushing coal is used as pulverized fuel, and the pulverized fuel is burned by a combustion burner, and the heat generated by this combustion is exchanged with water supply or steam to exchange heat with superheated steam. To generate. In the following description, "upper" and "upper" mean the upper side in the vertical direction, and "lower" and "lower" mean the lower side in the vertical direction.

The boiler 10 has a furnace 11 and a combustion device 12. The furnace 11 has a hollow shape of a square cylinder and is installed along the vertical direction. The furnace wall (heat transfer tube) constituting the furnace 11 is composed of a plurality of evaporation tubes and fins connecting them, and heat generated by combustion of fine fuel is exchanged with water supply or steam to exchange heat with the water supply or steam. The temperature rise is suppressed.

The combustion device 12 is provided on the lower side of the furnace wall constituting the furnace 11. The combustion device 12 has a plurality of combustion burners mounted on the furnace wall. For example, the combustion burners are arranged at equal intervals along the circumferential direction of the furnace 11 as one set, and are arranged in a plurality of stages along the vertical direction. However, the shape of the furnace 11, the number of combustion burners in one stage, and the number of stages are not limited to this.

Each combustion burner is connected to a plurality of crushers (not shown) via a pulverized coal supply pipe. Although not shown, in this crusher, for example, a rotary table is rotatably supported in the housing of the crusher, and a plurality of rollers are rotatably supported above the rotary table in conjunction with the rotation of the rotary table. It is configured. When coal is thrown between a plurality of rollers and a rotary table, it is crushed to a predetermined size of pulverized coal, and is crushed by a transport gas (primary air, oxidizing gas) in a crusher housing (not shown). The pulverized fuel conveyed to the classifier and classified within a predetermined size range can be supplied to the combustion burner from the pulverized coal supply pipe.

Further, the furnace 11 is provided with a wind box (not shown) at the mounting position of each combustion burner, and one end of an air duct is connected to this wind box. A forced ventilator (FDF: Forced Draft Fan) is provided at the other end of the air duct.

The combustion gas emitted from the furnace 11 passes through an evaporator (not shown), a superheater 102, a reheater 103, and an economizer (not shown), and exchanges heat with water supply and steam.

The combustion gas that has undergone heat exchange passes through the flue, is guided to the air heater after the nitrogen oxides in the combustion gas are removed by the denitration device, and exchanges heat with the combustion air. Then, the combustion gas passes through a dust collector such as an electrostatic precipitator and a desulfurization device, and is discharged from the chimney.

On the other hand, when a plurality of crushers are driven, the generated pulverized fuel is supplied to the combustion burner together with the transport gas through the pulverized coal supply pipe. Further, by exchanging heat with the exhaust gas discharged from the flue of the boiler 10 by the air heater, the heated combustion air (secondary air) is supplied from the air duct to each combustion burner of the combustion device 12 via the air box. Will be done. Then, the combustion burner blows the pulverized fuel mixture, which is a mixture of the pulverized fuel and the transport gas, into the furnace 11 and the combustion air into the furnace 11, and ignites at this time to form a flame. A flame is generated in the lower part of the furnace 11, and the high-temperature combustion gas rises in the furnace 11 and is discharged toward the superheater 102 and the like.

After that, the combustion gas is heat-exchanged by an evaporator (not shown), a superheater 102, a reheater 103, and an economizer (not shown), and then nitrogen oxides are reduced and removed by a denitration device to collect dust. Particulate matter is removed by the device, sulfur oxides are removed by the desulfurization device, and then discharged from the chimney into the atmosphere. It should be noted that the heat exchangers do not necessarily have to be arranged in the above-mentioned order with respect to the combustion gas flow.

The steam turbines 111 and 113 are rotationally driven by the steam generated by the boiler 10, and the generator 80 is rotationally driven by these steam turbines 111 and 113 to generate electricity.

The steam turbine 111 is a high-medium pressure steam turbine, and the superheated steam (main steam) superheated by the superheater 102 is guided to the high-pressure steam turbine portion of the steam turbine 111. The steam discharged from the steam turbine 111 becomes superheated steam (reheated steam) reheated by the reheater 103, and is guided to the medium pressure steam turbine portion of the steam turbine 111. The steam turbine 113 is a low-pressure steam turbine, and the steam discharged from the medium-pressure steam turbine portion of the high-medium-pressure steam turbine 111 is guided.

<Configuration of water treatment equipment>
Next, the configuration of the water treatment device 3 for treating the condensate water led from the condenser 20 and the drain water led from the water supply heater will be described.
A condenser 20 is connected to the downstream side of the low-pressure steam turbine 113. In the condenser 20, the steam rotationally driven by the low-pressure steam turbine 113 is cooled by cooling water (for example, seawater) to become condensate (condensed water).

The condenser 20 is provided with a first condenser pipe 21 for supplying condensed water. A filtration device 22 is provided at the downstream end of the first condensate pipe 21. The filtration device 22 removes iron present in water (condensate or drain water). The first condensate pipe 21 is provided with a condensate pump 24 on the upstream side of the filtration device 22.

In the first condensate pipe 21, a first iron concentration meter 26, a condensate outer blow pipe 27, and a condensate bypass pipe 28 are provided between the condensate pump 24 and the filtration device 22 in order in the condensate flow direction. Has been done.
As the ferrous iron densitometer 26, a total iron densitometer is used. However, the iron concentration may be obtained by using a correlation with the iron concentration prepared in advance using a turbidity meter. The measured value of the ferrous iron concentration meter 26 is transmitted to the control unit 30.
The return water system outer blow pipe 27 is provided with a return water system outer blow valve 27a. The control unit 30 opens and closes the external blow valve 27a of the condensate system.
The condensate bypass pipe 28 is provided between the first condensate pipe 21 and the second condensate pipe 32 connected to the downstream side of the filtration device 22 so as to bypass the filtration device 22. The condensate bypass pipe 28 is provided with a condensate bypass valve 28a. The condensate bypass valve 28a is opened and closed by the control unit 30.

A condensate desalination device 34 is connected to the downstream end of the second condensate pipe 32. In the condensate desalting apparatus 34, for example, an ion exchange resin is used to remove ions that cause scale generation and corrosion in each system of boiler water supply such as sodium ions, steam, and condensate. The condensate desalting device 34 is provided, for example, so that four towers are connected in parallel, three towers are used for passing water, and the remaining one tower is used as a spare for regeneration and standby. The spare towers will be switched and operated in sequence.

The third condensate pipe 36 is connected to the condensate desalting device 34. The downstream end of the third condenser pipe 36 is connected to the ground steam condenser 38. In the ground steam condenser 38, the ground steam discharged from the steam turbines 111 and 113 is heat-exchanged with the condensate supplied from the condensate 20 by the third condensate pipe 36, and becomes condensate (condensed water). Become. The third condensate pipe 36 is provided with a condensate booster pump 40 for sending condensate. The arrow A1 in the figure indicates the flow direction of the condensate water.

The fourth condenser pipe 42 is connected to the downstream side of the ground steam condenser 38. A low-pressure water supply heater (water supply heater) 44 is connected to the downstream end of the fourth condensate pipe 42. A condensate circulation pipe 43 is connected to the fourth condensate pipe 42. The downstream end of the condensate circulation pipe 43 is connected to the condensate 20. The condensate circulation pipe 43 is used at the time of cleaning up the condensate at the time of starting the power plant.

In the present embodiment, the low-pressure water supply heater 44 includes, for example, three low-pressure water supply heaters 44, and the first low-pressure water supply heater 44a, the second low-pressure water supply heater 44b, and the third low-pressure water supply heater 44c are provided in order in the flow direction of the condensate. It has. Bleed air pipes 45a, 45b, 45c for extracting steam from the low-pressure steam turbine 113 are connected to the low-pressure water supply heaters 44a, 44b, 44c, respectively. The pressure of the bleed steam supplied to each of the low-pressure water supply heaters 44a, 44b, 44c increases in the order of the first low-pressure water supply heater 44a, the second low-pressure water supply heater 44b, and the third low-pressure water supply heater 44c.

In the present embodiment, the bleed steam obtained by heating the condensate with the first low-pressure water supply heater 44a is condensed into drain water, which is guided to the condensate 20 by the first low-pressure water supply heater drain pipe 46.

The bleed steam obtained by heating the condensate with the third low-pressure water supply heater 44c condenses into drain water and is guided to the second low-pressure water supply heater 44b. The extracted steam obtained by heating the condensate with the second low-pressure water supply heater 44b condenses into drain water, and together with the drain water led from the third low-pressure water supply heater 44c, the low-pressure water supply heater drain tank 48 is provided by the second low-pressure water supply heater drain pipe 48. You will be led to 50. The arrow A2 indicates the flow direction of the drain water flowing through the second low-pressure water supply heater drain pipe 48.

A third low-pressure water supply heater drain pipe 52 is connected to the low-pressure water supply heater drain tank 50. The downstream end of the third low-pressure water supply heater drain pipe 52 is connected to the filtration device 22. The third low-pressure water supply heater drain pipe 52 includes a low-pressure water supply heater drain pump 54, a second iron concentration meter 56, a low-pressure water supply heater drain recirculation pipe 58, and a low-pressure water supply heater drain system outer blow pipe 60 in order in the drain water flow direction. And a bypass pipe 62 for draining the low-pressure water supply heater are provided.

As the ferric iron densitometer 56, a total iron densitometer is used. However, the iron concentration may be obtained by using a turbidity meter as in the iron concentration meter 26. The measured value of the ferric iron concentration meter 56 is transmitted to the control unit 30.
The downstream end of the low-pressure water heater drain recirculation pipe 58 is connected to the low-pressure water heater drain tank 50.

The low-pressure water supply heater drain system outer blow pipe 60 is provided with a condensate system outer blow valve 60a. The control unit 30 opens and closes the external blow valve 60a of the condensate system.

The downstream end of the low-pressure water supply heater drain bypass pipe 62 is connected to the fourth low-pressure water supply heater drain pipe (drain water return pipe) 64 connected to the downstream side of the filtration device 22 so as to bypass the filtration device 22. The low-pressure water supply heater drain bypass pipe 62 is provided with a drain bypass valve 62a. The drain bypass valve 62a is opened and closed by the control unit 30.

The downstream end of the fourth low-pressure water supply heater drain pipe 64 joins the condensate between the second low-pressure water supply heater 44b and the third low-pressure water supply heater 44c at an intermediate position of the low-pressure water supply heater 44. It is connected. The arrow A3 indicates the flow direction of the drain water.
The position where the downstream end of the fourth low-pressure water supply heater drain pipe 64 is connected is determined by the temperature of the drain water flowing through the fourth low-pressure water supply heater drain pipe 64. That is, the drain water merges with the condensate by selecting an intermediate position or a downstream position of each of the plurality of low-pressure water heaters 44 having a temperature equivalent to the temperature of the drain water flowing through the fourth low-pressure water heater drain pipe 64. To do. Therefore, depending on the temperature of the drain water flowing through the fourth low-voltage water supply heater drain pipe 64 depending on the configuration of the power plant 1, the first low-voltage water supply heater 44a and the second low-pressure water supply heater 44b may be used, and the third low-voltage water supply heater 44c may be used. It may be on the downstream side (downstream side of the low-pressure water supply heater 44). It should be noted that the same temperature does not have to be the same temperature, and it is preferable that the temperature difference is small from the viewpoint of reducing the heat loss of the power plant 1. Therefore, for example, the temperature difference is preferably within 5 ° C.

A low-pressure water heater drain circulation pipe 66 is provided between the low-pressure water heater drain tank 50 and the condenser 20. The low-pressure water supply heater drain circulation pipe 66 is provided with a drain circulation valve 66a and a ferrous iron concentration meter 67. The drain circulation valve 66a is opened and closed by the control unit 30. As the ferric iron densitometer 67, a total iron densitometer is used. However, the iron concentration may be obtained by using a turbidity meter as in the iron concentration meter 26. The measured value of the ferrous iron concentration meter 67 is transmitted to the control unit 30. When the application is limited to measuring the iron concentration of the low-pressure water heater drain tank 50 when the power plant 1 is started, the value of the ferric iron concentration meter 56 is omitted and the value of the ferric iron concentration meter 56 is substituted. May be good.

From the outlet of the low-pressure water supply heater 44, the restored water is supplied as water supply (boiler water supply). A deaerator 70, a water supply pump 72, a water supply valve 74, and a high-pressure water supply heater 76 are provided in this order on the downstream side of the water supply flow of the low-pressure water supply heater 44. Although not shown, the high-pressure water heater 76 is guided with steam extracted from the high-medium-pressure steam turbine 111. The water supply heated by the high-pressure water supply heater 76 is guided to the economizer of the boiler 10. The arrow A4 indicates the flow direction of the water supply.

A make-up water tank 78 is connected to the condenser 20, and pure water is supplied by the make-up water pump 79.

The control unit 30 includes, for example, a CPU (Central Processing Unit) and a RAM (Random Access).
It is composed of a memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. Then, as an example, a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is installed in a ROM or other storage medium in advance, is provided in a state of being stored in a computer-readable storage medium, or is distributed via a wired or wireless communication means. Etc. may be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

<Configuration around the filtration device 22>
FIG. 2 shows the periphery of the filtration device 22. The same components as those shown in FIG. 1 have the same reference numerals.

As shown in the figure, the filtration device 22 is composed of, for example, two towers in the present embodiment, and includes a first tower (divided filtration unit) 22a and a second tower (divided filtration unit) 22b. ing. The filtration device 22 may be composed of a plurality of towers, and may be composed of three or more towers. The capacity of the filtration device 22 is determined based on the maximum flow rate value of the filtration flow rate during the period in which condensate is passed through and filtration is required when the power plant 1 is started. For example, the capacity of the filtration device 22, that is, the total capacity of each tower (total capacity of the two towers) is the maximum water flow rate of the power plant 1 (for example, 50% load operation which temporarily becomes the maximum water flow rate at startup). It is determined based on the return water flow rate at the time. During normal operation of the power plant 1, the drain water of the low-pressure water supply heater 44b is switched to as described later, and the flow rate of water that requires filtration decreases. Therefore, either the first tower 22a or the second tower 22b is operated. The other can be reserved.

The first tower 22a and the second tower 22b are provided so as to be connected in parallel to the fluid flow of the condensate water and the drain water. The first tower 22a and the second tower 22b have the same capacity. That is, each of the towers 22a and 22b has a capacity of 1/2 of the capacity of the filtration device.

The first tower upstream valve 22a1 is provided on the upstream side of the first tower 22a, and the first tower downstream valve 22a2 is provided on the downstream side of the first tower 22a. The second tower upstream valve 22b1 is provided on the upstream side of the second tower 22b, and the second tower downstream valve 22b2 is provided on the downstream side of the second tower 22b. The first tower upstream valve 22a1, the first tower downstream valve 22a2, the second tower upstream valve 22b1 and the second tower downstream valve 22b2 are opened and closed by the control unit 30, respectively. Whether the fluid flows only in the first tower 22a or only in the second tower 22b by the first tower upstream valve 22a1, the first tower downstream valve 22a2, the second tower upstream valve 22b1 and the second tower downstream valve 22b2. , It is switched whether to flow the fluid through both the first tower 22a and the second tower 22b.

The first condensate pipe 21 is provided with a condensate inlet valve 21a (indicated by a black circle in FIG. 1) between the branch position B1 of the condensate bypass pipe 28 and the filtration device 22. The second condensate pipe 32 is provided with a condensate outlet valve 32a (indicated by a black circle in FIG. 1) between the filtration device 22 and the confluence position B2 of the condensate bypass pipe 28. The condensate inlet valve 21a and the condensate outlet valve 32a are opened and closed by the control unit 30, respectively.

The third low-pressure water supply heater drain pipe 52 is provided with a drain water inlet valve 52a (indicated by a black circle in FIG. 1) between the branch position C1 of the low-pressure water supply heater drain bypass pipe 62 and the filtration device 22. The fourth low-pressure water supply heater drain pipe 64 is provided with a drain water outlet valve 64a (indicated by a black circle in FIG. 1) between the filtration device 22 and the confluence position C2 of the low-pressure water supply heater drain bypass pipe 62. The drain water inlet valve 52a and the drain water outlet valve 64a are opened and closed by the control unit 30, respectively.

The condensate inlet valve 21a, the condensate outlet valve 32a, the condensate bypass valve 28a, the drain water inlet valve 52a, the drain water outlet valve 64a, and the drain bypass valve 62a constitute the switching means. By this switching means, whether the condensate water guided from the condenser 20 flows to the filtration device 22 or the drain water guided from the second low-pressure water supply heater 44b and the third low-pressure water supply heater 44c flows to the filtration device 22. Be selected.

<Operation of water treatment equipment when starting a power plant>
Next, the operation of the water treatment device 3 at the start of the power generation plant 1 will be described with reference to FIG.
First, after the power plant is stopped, the iron concentration in the boiler water supply system tends to increase due to elution of iron from carbon steel-based parts such as pipes. Iron may flow into the boiler 10's evaporation pipe together with the boiler water supply, and scale (powder scale) with low thermal conductivity may adhere and accumulate on the inner surface of the boiler 10. Therefore, the boiler ignition when starting the boiler 10 may occur. In doing so, the water quality of the boiler water supply system is managed to satisfy the water quality standard of the boiler water supply (for example, the iron concentration in the boiler inlet water supply is specified by the JIS standard as the predetermined control standard value of 5 ppb or less during rated load operation). Therefore, cleanup operations are carried out in sequence.

Condensation cleanup is performed by the following procedures (1) and (2).
(1) Exoplanet blow When the power plant 1 is started, an exoplanet blow is performed. Specifically, in order to reduce the iron concentration in the condenser 20, pure water is supplied to the condenser 20 from the make-up water tank 78, and the condenser outside blow valve 27a is opened to blow the condenser outside. Blow out the condensate from the pipe 27 to the outside of the system. In this extra-system blow, until the iron concentration of the condensate measured by the first iron concentration meter 26 installed at the outlet of the condensate pump 24 becomes equal to or less than the first predetermined value that enables water to pass through the filtration device 22. continue.
At this time, the low-pressure water supply heater 44 is stopped, and the low-pressure water supply heater 44 is not drained. In addition, water is not passed through the filtration device 22 and the condensate desalting device 34.
The first predetermined value is set based on the concentration at which water can pass through the filtration device, and may be about several thousand ppb (for example, 1,000 to 5,000 ppb) in the present embodiment.
Condensation means water derived from the condenser 20, and does not mean only water condensed from steam. Therefore, even when the power plant 1 is started, it means condensate, although it is not condensed water.

(2) Circulation operation After the iron concentration of the condensate reaches the first predetermined value or less by the extra-system blow of the above (1), the circulation operation is started. In the circulation operation, the outer blow valve 27a of the condensate system is closed, and the condensate from the condensate 20 is passed through the filtration device 22 and the condensate desalting device 34. FIG. 4A shows the water flow state at this time. In the figure, the valve shown in black means closed, and the valve shown in white means open. As shown in the figure, the condensate inlet valve 21a and the condensate outlet valve 32a are opened, and the drain water inlet valve 52a and the drain water outlet valve 64a are closed. As a result, water is passed through the first tower 22a and the second tower 22b of the filtration device 22. When the condensate flow rate is small, either the first tower 22a or the second tower 22b may be used.

The condensate that has passed through the condensate desalting device 34 is circulated by being returned to the condensate 20 via the condensate circulation pipe 43. By circulating the condensate in this way, the residual iron remaining in the pipe on the downstream side of the branch point of the blow pipe 27 outside the condensate system passes through the condenser 20 and is dewatered with the filtration device 22. Since it is removed by the salt device 34, the water quality can be purified. Even if the iron concentration of the condensate from the condenser 20 increases during the circulation operation, the iron concentration at the inlet of the condensate desalting device 34 can be reduced by the filtration device 22, so that the blow outside the condensate system is blown. It is not necessary to perform extra-system blow using the pipe 27.

(3) Cleanup of other equipment After the condensate cleanup is completed as described above, the deaerator 70 heats and degass the condensate to perform low pressure cleanup of the low pressure water supply heater 44 and the deaerator 70. .. After that, the water supply pump 72 is started to perform high-pressure cleanup of the high-pressure water supply heater 76.
In these cleanup processes as well, extra-system blow and circulation operation are performed to manage the water quality of the boiler water supply system. After the high-pressure cleanup is completed, the ventilation system is started and the water supply to the boiler 10 is started.

(4) Boiler ignition After starting water supply to the boiler 10, the boiler 10 is ignited to start the boiler.

(5) Start of power plant operation The steam generated by starting the boiler 10 is ventilated to the steam turbines 111 and 113, and the power generation operation of the power plant is started after warming, speeding up, and merging.

(6) Increase in power plant load After reaching a predetermined power plant load (for example, 15% load), a part of the steam flowing through the low-pressure steam turbine 113 is bleeded using the bleed pipes 45a, 45b, 45c, and the low-pressure water heater 44 Start supplying to. Each extracted steam exchanges heat with water supply at a plurality of low-pressure water supply heaters 44a, 44b, 44c and is condensed to become a low-pressure water supply heater drain, and the drain water generated at the first low-pressure water supply heater 44a is sent to the condenser 20 and second. The drain water generated by the low-pressure water supply heater 44b and the third low-pressure water supply heater 44c is collected in the low-pressure water supply heater drain tank 50.

(7) Low-voltage water supply heater Drain cleanup After the power plant is stopped, the iron concentration in the drain system of the low-voltage water supply heater 44 tends to increase, and the bleed steam is started to be supplied to the low-voltage water supply heater 44, so that the low-voltage water supply heater 44 The iron concentration is highest when the operation is started. Therefore, after the supply of the bleed steam is started, the drain system of the low-pressure water supply heater 44 is cleaned up according to the following procedures (a) and (b) to control the water quality.
(A) Extra-system blow (for example, power plant load is 15% to 20% load)
The drain water generated by the second low-pressure water supply heater 44b and the third low-pressure water supply heater 44c is collected in the low-pressure water supply heater drain tank 50, and the iron concentration of the drain water measured by the second iron concentration meter 56 is the second predetermined value. It is discharged to the outside of the system through the low-pressure water supply heater drain system outside blow pipe 60 until it becomes the following. The second predetermined value in the present embodiment may be about several hundred ppb (for example, 300 to 800 ppb).
(B) Circulation operation (for example, power plant load is 20% to 50% load)
After the iron concentration of the drain water reaches the second predetermined value by the extra-system blow of the above (a), the condensate-external blow valve 60a is closed, the drain circulation valve 66a is opened, and the low-pressure water supply heater drain circulation pipe 66 is opened. The drain water is collected in the condenser 20 through the circulation, and the iron concentration of the drain water is reduced to the third predetermined value or less. The third predetermined value in the present embodiment may be about several tens of ppb (for example, 30 to 80 ppb).
At this time, the measurement is performed by the ferric iron concentration meter 56 while performing the mini-flow operation of the low-pressure water supply heater drain pump 54 (via the low-pressure water supply heater drain recirculation pipe 58). In addition, you may measure directly with the 3rd iron concentration meter 67 installed in the low pressure water supply heater drain circulation pipe 66.

The drain water of the first low-pressure water supply heater 44a is supplied to the condenser 20 via the first low-pressure water supply heater drain pipe 46 and circulated to perform cleanup.

(8) Switching of water flow to the filtration device 22 (for example, the power plant load is 50% to 100%)
After the iron concentration of the drain water reaches the third predetermined value or less, the circulation operation of the drain water described in (b) above is terminated, and the water flow to the filtration device 22 is switched from the condensate water to the drain water. That is, the state of FIG. 4A is switched to the state of FIG. 4B. In FIG. 4B, as in FIG. 4A, the valve shown in black means closed, and the valve shown in white means open. The iron content in the drain water derived from the second low-pressure water supply heater 44b and the third low-pressure water supply heater 44c is removed by the filtration device 22, and the water quality standard of the boiler supply water can be satisfied.

For condensate, after opening the condensate bypass valve 28a, the condensate outlet valve 32a is closed, then the condensate inlet valve 21a is closed, and the condensate device 22 is bypassed via the condensate bypass pipe 28. Pass water through the condensate demineralizer 34. At this time, since the concentration of iron present in the condensate has dropped to the second predetermined value or less, the iron in the condensate is removed by the condensate desalting device 34 and satisfies the water quality standard of the boiler feed water. be able to.

After completing the switching of the condensate to the condensate bypass pipe 28, the drain water guided from the low-pressure water supply heater 44 opens the drain water inlet valve 52a, and then opens the drain water outlet valve 64a. The drain bypass valve 62a is closed and supplied to the filtration device 22. As shown in FIG. 4B, since the flow rate of the drain water is smaller than that of the condensate water, it is sufficient to pass water to one tower, and for example, only the first tower 22a may be used. The second tower 22b is used as a spare and is used alternately with the first tower 22a while being regenerated.

The drain water that has passed through the filtration device 22 is returned to the condensate, which is the fluid to be heated by the low-pressure water supply heater 44, and supplied via the fourth low-pressure water supply heater drain pipe 64.
By selectively switching the water flow as described above, the condensate water led from the condenser 20 and the drain water led from the second low-pressure water supply heater 44b and the third low-pressure water supply heater 44c are each. The fluid does not pass through the filtration device 22 at the same time.

The effects of the present embodiment described above are as follows.
The filtration device 22 removes iron from the condensate water led from the condenser 20, and also removes iron from the drain water led from the low-pressure water supply heater 44. In this way, it was decided to perform the iron removal treatment of the condensate and the drain water with the common filtration device 22. Then, the condensate water and the drain water are selectively guided to the filtration device 22. As a result, the equipment cost can be reduced by sharing the filtration device 22, and it is not necessary to significantly increase the capacity of the filtration device 22 by selectively guiding the condensate and drain water. Further, since the drain water having a predetermined amount of heat is not mixed with the condensate at room temperature, it joins the middle position or the downstream side position of the low pressure water supply heater 44 so that the temperature becomes the same as the temperature of the drain water. , The heat loss of the power plant 1 can be reduced.

Since it was decided to selectively guide the condensate and the drain water to the filtration device 22, the capacity is filtered based on the total amount of the maximum flow of the condensate and the maximum flow of the drain water during the period when the condensate is required to be filtered. It does not have to be the device 22. Since the condensate has a larger flow rate than the drain water, the capacity of the filtration device 22 is determined based on, for example, the required flow rate of the condensate to the filtration device 22 that maximizes the condensate at the start of the power plant.

It was decided to install a plurality of towers 22a and 22b so that the filtration devices 22 would be connected in parallel. As a result, when condensate is flowed, condensate is flowed to all the towers 22a and 22b divided in parallel, while when drain water is flowed, the flow rate is smaller than that of condensate, so only one tower 22a and 22b is flown. Pour drain water into the water. The towers 22b and 22a through which drain water does not flow can be operated as a spare. Here, when the condensate is flown, it is sufficient to pass the water through the filtration device only for a temporary predetermined period at the time of starting the boiler, and a spare filtration device tower is not required. On the other hand, drain water needs to be filtered during normal operation, which is the period during which heating is performed by a low-pressure water supply heater after the power plant is started, so it is necessary to operate it while alternately regenerating it in consideration of reserves. ..

The condensate desalting device 34 removes ions such as sodium, but can also remove iron. Therefore, even when the condensate does not pass through the filtration device 22, the iron content can be removed by the condensate desalting device 34, so that the increase in the iron concentration in the condensate can be suppressed and the boiler water can be supplied. Can meet the water quality standards of.

The drain water filtered by the filtration device 22 is merged with the middle position of the low-pressure water supply heater 44, that is, between the second low-pressure water supply heater 44b and the third low-pressure water supply heater 44c by the fourth low-pressure water supply heater drain pipe 64. As a result, drain water having a predetermined amount of heat can be merged with the position on the downstream side of the low-pressure water supply heater 44 so as to be condensate flowing through the water supply heater having the same temperature, and the heat loss of the power plant 1 can be reduced. Can be reduced.

When the iron concentration of the drain water became equal to or less than the third predetermined value, the fluid flowing through the filtration device 22 was switched from condensate to drain water. Thereby, the drain water can be treated appropriately. Since the iron content of the condensate can be removed by the condensate desalting device 34 provided on the downstream side of the filtration device 22, the water quality standard of the boiler feed water can be satisfied.

The water treatment apparatus, the power plant, and the water treatment method described in each of the above-described embodiments are grasped as follows, for example.

The water treatment device according to one aspect of the present disclosure is a filtration device that removes iron from the condensate led from the condenser (20) and removes iron from the drain water led from the water supply heater (44). 22), the flow of the condensate from the condenser (20) to the filtration device (22), and the flow of the drain water from the water supply heater (44) to the filtration device (22). (21a, 32a, 28a, 52a, 64a, 62a) are provided.

The filtration device removes iron from the condensate derived from the condenser and also removes iron from the drain water led from the water supply heater. In this way, it was decided to perform the iron removal treatment of the condensate and drain water with a common filtration device. Then, the condensate water and the drain water were selectively guided to the filtration device by the switching means. As a result, it is possible to reduce the equipment cost by sharing the filtration device, and it is not necessary to significantly increase the capacity of the filtration device by selectively guiding the condensate and the drain water. Further, since the drain water having a predetermined calorific value is not mixed with the condensate at room temperature, the heat loss of the power plant can be reduced.
The condensate means water derived from the condenser, and does not mean only water condensed from steam. Therefore, even when the power plant is started, it means condensate, although it is not condensed water.

In the water treatment device according to one aspect of the present disclosure, the capacity of the filtration device (22) is determined based on the maximum value of the required filtration flow rate when the condensate flows toward the filtration device.

Since it was decided to selectively guide the condensate and drain water to the filtration device by the switching means, the capacity based on the total amount of the maximum flow of condensate and the maximum flow of drain water during the period when condensate filtration is required. There is no need to use a condenser. In general, at any power plant load, the condensate flow rate is higher than the drain water of the low pressure water supply heater, so the filter device is based on the maximum value of the required filtration flow rate during the period in which the condensate water is passed through the filter device. All you have to do is determine the capacity.

In the water treatment device according to one aspect of the present disclosure, the filtration device (22) includes divided filtration units (22a, 22b) divided into a plurality of parts so as to be in parallel.

The filtration device may be divided into a plurality of parts so as to be connected in parallel. As a result, when condensate that requires filtration is flowed only for a temporary period when the power plant is started, condensate is flowed to all the divided filtration sections divided in parallel, while after the power plant is started. During normal operation, when heating is performed by a low-pressure water supply heater, when drain water that requires filtration is flowed, the flow rate is smaller than that of condensate, so drain water is applied only to a part (one) of the divided filtration parts. Shed. The other divided filtration unit through which drain water does not flow can be operated as a spare so that it can be regenerated.
For example, two divided filtration units having the same capacity are used.

The water treatment device according to one aspect of the present disclosure is provided with a condensate desalting device (34) in which the condensate flowing out of the filtration device (22) is guided.

The condensate desalination device removes ions such as sodium, but it can also remove iron. Therefore, even when the condensate is not passed through the filtration device by the switching means, the iron content can be removed by the condensate desalting device and the water quality standard of the boiler feed water can be satisfied.

The water treatment device according to one aspect of the present disclosure includes a drain water return pipe (64) for merging the drain water flowing out of the filtration device (22) to an intermediate position or downstream of the water supply heater (44). There is.

The drain water filtered by the filtration device is merged at an intermediate position or downstream of the water supply heater by the drain water return pipe. As a result, drain water having a predetermined amount of heat can be merged with the position on the downstream side of the low-pressure water supply heater 44 so as to be condensate flowing through the water supply heater having the same temperature, and the heat loss of the power plant is reduced. can do.
For example, when a plurality of water supply heaters are divided in series, a drain water return pipe is connected between the divided water supply heaters.

In the water treatment device according to one aspect of the present disclosure, the iron densitometer (56) for detecting the iron concentration of the drain water guided to the filtration device (22) and the measured values of the iron densitometer (56) are predetermined. When the value is equal to or less than the value, the control unit (30) switches the fluid guided to the filtration device (22) from the condensate water to the drain water by the switching means (21a, 32a, 28a, 52a, 64a, 62a). ) And.

When the iron concentration of the drain water falls below a predetermined value, the fluid flowing through the filtration device is switched from condensate to drain water. Thereby, the drain water can be treated appropriately.
When a condensate desalting device is provided on the downstream side of the filtration device, the iron content of the condensate can be removed by the condensate desalting device, which is particularly effective.

In the water treatment apparatus according to one aspect of the present disclosure, the control unit (30) uses the fluid guided to the filtration apparatus (22) at the start of the power plant (1) provided with the water supply heater (44). Switch from condensate to the drain water.

Drain water is generated from the time when the heating of the water supply by the water supply heater is started when the power plant is started, and by cleaning up the drain system, the inside of the system is purified and the iron concentration of the drain water decreases. Therefore, it is appropriate to switch the fluid flowing through the filtration device from condensate to drain water while confirming the decrease in iron concentration in the drain water when the power plant is started.

The power plant according to one aspect of the present disclosure includes the water treatment apparatus described in any of the above, a boiler (10) that generates steam by using condensate supplied from the water treatment apparatus as water supply, and the boiler (10). It is provided with a power generation unit that generates electricity using the steam generated by 10).

The water treatment method according to one aspect of the present disclosure is a filtration device that removes iron from the condensate led from the condenser (20) and removes iron from the drain water led from the water supply heater (44). In the water treatment method using 22), the flow of the condensate from the condenser (20) to the filtration device (22) and the drain water from the water supply heater (44) to the filtration device (22). The flow toward (22) is selectively switched.

In the above-described embodiment, the boiler 10 is a coal-fired boiler, but the solid fuel is a boiler that uses biomass fuel, PC (Petroleum Coke) fuel generated during petroleum refining, petroleum residue, or the like. You may. In addition, not only solid fuel but also liquid fuel such as petroleum, heavy oil, and factory effluent can be used as fuel, and gaseous fuel (natural gas, petroleum gas, by-product gas in steelmaking process, etc.) can be used as fuel. Etc.) can also be used. It can also be applied to a co-firing boiler of these fuels.

1 Power plant 3 Water treatment device 10 Boiler 11 Fire furnace 12 Combustion device 20 Condenser 21 1st condensate pipe 21a Condensation inlet valve 22 Filtration device 22a 1st tower (split filtration unit)
22a1 1st tower upstream valve 22a2 1st tower downstream valve 22b 2nd tower (split filtration section)
22b1 2nd tower upstream valve 22b2 2nd tower downstream valve 24 Condensate pump 26 1st iron concentration meter 27 Condensate system outside blow pipe 27a Condensation system outside blow valve 28 Condensation bypass pipe 28a Condensation bypass valve 30 Control unit 32 2nd Condensation pipe 32a Condensation outlet valve 34 Condensation desalting device 36 Third condensate pipe 38 Ground steam condenser 40 Condensation booster pump 42 Fourth condensate pipe 43 Condensation circulation pipe 44 Low pressure water supply heater (water supply heater)
44a 1st low pressure water supply heater 44b 2nd low pressure water supply heater 44c 3rd low pressure water supply heater 45a, 45b, 45c Extraction pipe 46 1st low pressure water supply heater Drain pipe 48 2nd low pressure water supply heater Drain pipe 50 Low pressure water supply heater Drain tank 52 3rd low pressure water supply Heater drain piping 52a Drain water inlet valve 54 Low pressure water supply heater Drain pump 56 2nd iron concentration meter 58 Low pressure water supply heater Drain recirculation piping 60 Low pressure water supply heater Drain system outer blow piping 60a Restoration system outer blow valve 62 Low pressure water supply heater Drain bypass piping 62a For drain Bypass valve 64 4th low pressure water supply heater Drain pipe (drain water return pipe)
64a Drain water outlet valve 66 Low pressure water supply heater Drain circulation piping 66a Drain circulation valve 67 Third iron concentration meter 70 Deaerator 72 Water supply pump 74 Water supply valve 76 High pressure water supply heater 78 Replenishment water tank 79 Replenishment water pump 80 Generator 102 Superheater 103 Reheater 111 Steam Turbine (High Medium Pressure Steam Turbine)
113 Steam turbine (low pressure steam turbine)

Claims (9)

1. A filtration device that removes iron from the condensate led from the condenser and removes iron from the drain water led from the water supply heater that heats the condensate.
   Switching means for selectively switching between the flow of the condensate from the condenser to the filtration device and the flow of the drain water from the water supply heater to the filtration device.
   A water treatment device equipped with.
2. The water treatment device according to claim 1, wherein the capacity of the filtration device is determined based on the maximum value of the required filtration flow rate when the condensate water flows toward the filtration device.
3. The water treatment device according to claim 2, wherein the filtration device includes a split filtration unit divided into a plurality of parts so as to be connected in parallel.
4. The water treatment device according to any one of claims 1 to 3, wherein a condensate desalting device for guiding the condensate flowing out of the filtration device is provided.
5. The water treatment device according to any one of claims 1 to 4, further comprising a drain water return pipe for merging the drain water flowing out of the filtration device to an intermediate position or downstream of the water supply heater.
6. An iron densitometer that detects the iron concentration of the drain water guided to the filtration device,
   A control unit that switches the fluid guided to the filtration device from the condensate to the drain water by the switching means when the measured value of the iron concentration meter becomes a predetermined value or less.
   The water treatment apparatus according to any one of claims 1 to 5.
7. The water treatment device according to claim 6, wherein the control unit switches the fluid guided to the filtration device from the condensate to the drain water when the power plant provided with the water supply heater is started.
8. The water treatment apparatus according to any one of claims 1 to 7.
   A boiler that generates steam by using the condensate supplied from the water treatment device as water supply,
   A power generation unit that generates electricity using the steam generated by the boiler,
   Power plant equipped with.
9. It is a water treatment method using a filtration device that removes iron from the condensate derived from the condenser and also removes iron from the drain water guided from the water supply heater.
   A water treatment method for selectively switching between a flow of condensate from the condenser to the filtration device and a flow of drain water from the water supply heater to the filtration device.

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