JP2011241998A - Boiler starting device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler starting device capable of starting a boiler so that dissolved oxygen in water supplied to the boiler satisfies a regulated value without the need of supply of auxiliary steam.SOLUTION: A recirculation system operating unit 28 performs normal mode operation securing a necessary minimum flow rate of a water supply pump 24 when there is supply of auxiliary steam to a deaerator 16 and performs temperature increasing mode operation by circulating water of a water storage tank 18 to a recirculation system 20 and increasing the temperature of water of the water storage tank 18 when there is no supply of the auxiliary steam to the deaerator 16. A supply water amount adjusting unit 31 starts water supply to the boiler 11 when the temperature of water of the water storage tank 18 becomes a prescribed temperature satisfying the regulated value of dissolved oxygen concentration, and supplies water to the boiler while adjusting a supply water amount so that temperature of water of the water storage tank 18 does not become a predetermined limitation value or lower than it. An auxiliary steam supplying unit 34 supplies auxiliary steam to the deaerator 16 when auxiliary steam from the boiler 11 is established after water filling and ignition of the boiler.

Description

  The present invention relates to a boiler starter and a method for starting a boiler so that dissolved oxygen supplied to the boiler satisfies a specified value.

  In a thermal power plant equipped with a steam turbine, the steam generated in the boiler is guided to the steam turbine, the steam that has finished work in the steam turbine is condensed by the condenser, and then supplied to the boiler again. At that time, dissolved oxygen contained in the water supply is removed. This is to prevent the boiler tube from being corroded when the dissolved oxygen concentration of the feed water is high. There are two methods for removing dissolved oxygen, one using a deaerator and the other using chemicals such as hydrazine.

  The removal of dissolved oxygen by the deaerator is performed by bringing steam into contact with the condensate from the condenser to raise the temperature of the condensate and degassing. That is, the condensate from the condenser is injected into the deaeration chamber from the injection valve at the upper part of the deaerator and, while falling as fine water droplets, comes into contact with the heating steam to raise the temperature. Then, while the trays installed below are sequentially lowered, the condensate is heated to the saturation temperature, and dissolved oxygen in the condensate is reduced to supply water to the boiler.

  Thus, the removal of dissolved oxygen by the deaerator requires auxiliary steam for deaeration. While the boiler is in operation, auxiliary steam can be supplied from its own boiler, but when the boiler is stopped, auxiliary steam cannot be supplied from its own boiler. In order to remove the dissolved oxygen by the vessel, it is necessary to receive auxiliary steam from another boiler.

  Therefore, an auxiliary boiler for supplying auxiliary steam is provided, or in a power plant having a plurality of power generation units, any one power generation unit must be in an operating state so that auxiliary steam can be secured. I'm leaving.

  Degassing until the degassing function is enabled in the deaerator, assuming that the water supply with low dissolved oxygen concentration can be sent to the boiler without the help of other unit steam or auxiliary boiler steam when starting up the plant. Condensate water supply to the vessel is not performed, and during this time, the water supply necessary for the boiler is supplemented with water retained in the deaerator water storage tank (see, for example, Patent Document 1).

  In addition, an electric heater that uses surplus electricity during nighttime stoppage is installed on the outlet side of the deaerator circulation pump, and water is returned to the water storage tank through the circulation pipe to keep the water temperature constant, thereby preventing an increase in dissolved oxygen. Some have been designed to prevent a decrease in the water storage temperature (for example, see Patent Document 2).

Japanese Patent Publication No. 61-6287 JP 61-72903 A

  However, in the thing of patent document 1, since the dissolved oxygen concentration will increase when the time of a certain amount of time passes after the power generation unit stops, the water held in the deaerator water storage tank increases. Will not be able to start the boiler. Moreover, in the thing of patent document 2, since the water heated with the electric heater is returned to a water storage tank through a circulation pipe and the water storage temperature is kept constant, the increase in dissolved oxygen and the decrease in the water storage temperature are prevented. Although an increase in density can be prevented, not only an electric heater is required, but also electric power for driving the electric heater is required.

  The objective of this invention is providing the boiler starting apparatus and method which can start a boiler so that the dissolved oxygen of the feed water to a boiler satisfy | fills a regulation value, without supplying auxiliary steam.

  According to a first aspect of the present invention, there is provided a boiler starter comprising: an auxiliary steam determination unit that determines whether there is auxiliary steam to the deaerator when a boiler start command is received; and the deaerator by the auxiliary steam determination unit. When it is determined that there is auxiliary steam to the circulator, a part of the discharge flow rate of the feed water pump is circulated to the recirculation system of the deaerator to perform a normal mode operation to ensure the necessary minimum flow rate of the feed water pump, When it is determined that there is no supply of auxiliary steam to the deaerator, the temperature raising mode operation for raising the temperature of the water in the water storage tank by circulating the water in the water tank in the deaerator to the recirculation system When the auxiliary steam from the boiler to the deaerator is established, the recirculation system operation means for switching from the temperature increase mode operation to the normal mode operation, and the water storage in the temperature increase mode operation by the recirculation system operation means Tank When the temperature of the water reaches a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration, water supply to the boiler is started and the water supply flow rate is adjusted so that the temperature of the water in the water storage tank does not fall below a predetermined limit value. Supply water flow rate adjusting means for supplying water to the boiler, and auxiliary steam supply means for supplying auxiliary steam to the deaerator when the auxiliary steam from the boiler is established after water filling and ignition of the boiler Boiler starter characterized.

  The boiler starting method according to the invention of claim 2 determines whether or not there is auxiliary steam to the deaerator when there is an instruction to start the boiler, and when it is determined that there is auxiliary steam to the deaerator. Circulates a part of the discharge flow rate of the feed water pump to the recirculation system of the deaerator to perform the normal mode operation to ensure the necessary minimum flow rate of the feed water pump, and there is no supply of auxiliary steam to the deaerator When it is determined that the temperature of the water in the water storage tank is increased by performing a temperature rising mode operation in which the water in the water storage tank of the deaerator is circulated through the recirculation system to increase the temperature of the water in the water storage tank. When the temperature reaches a predetermined value that satisfies the specified value of the dissolved oxygen concentration, water supply to the boiler is started, and the flow rate of water supplied to the boiler is adjusted so that the temperature of the water in the water storage tank does not fall below a predetermined limit value. While supplying water to the boiler , When the auxiliary steam from the boiler water filling and after ignition of the boiler has been established to supply auxiliary steam to the deaerator, characterized in that the transition from the warm mode operation in the normal mode operation.

  According to the present invention, it is determined whether there is auxiliary steam to the deaerator when there is a boiler start command, and when there is auxiliary steam to the deaerator, normal mode operation is performed and When the auxiliary steam is not supplied, the temperature rise mode operation is performed in which the water in the storage tank of the deaerator is circulated through the recirculation system to raise the temperature. When auxiliary water from the boiler is established after water supply to the boiler is started and the boiler is filled and ignited, auxiliary steam is supplied from the boiler to the deaerator. Without requiring equipment such as an electric heater to prevent the concentration from increasing, the boiler can be started so that the dissolved oxygen supplied to the boiler satisfies the specified value.

The block diagram at the time of applying the boiler starting device which concerns on embodiment of this invention to the thermal power plant which has a steam turbine. The graph of the water temperature T of the water storage tank and dissolved oxygen concentration DO when starting the boiler starting device which concerns on embodiment of this invention in a certain thermal power plant. The flowchart which shows the boiler starting method which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram when a boiler starting device according to an embodiment of the present invention is applied to a thermal power plant having a steam turbine.

  The steam generated in the boiler 11 is guided to the steam turbine 12 to drive the steam turbine 12 and rotate the generator 13 connected to the steam turbine 12. Thereby, the generator 13 generates electric power and supplies the electric power to a power system (not shown).

  The steam that has finished work in the steam turbine 11 is guided to the condenser 14 and returned to the water by the condenser 14. The condensate returned to the water by the condenser 14 is guided to the deaeration chamber 17 of the deaerator 16 by the condensate pump 15 and stored in the water storage tank 18. The deaerator 16 includes a deaeration chamber 17 and a water storage tank 18. The deaeration chamber 17 sprays water from above and is directly heated by auxiliary steam supplied from the boiler 11 via an auxiliary steam pressure control valve 19. Then, the dissolved oxygen gas in the water is separated and removed. The degassed water is stored in the water storage tank 18. Note that, when the boiler 11 is not activated, the auxiliary steam is not supplied via the auxiliary steam pressure control valve 19, so that the dissolved oxygen gas in the water is not separated and removed by the auxiliary steam.

  The deaerator 16 is provided with a recirculation pump 21, which is activated when the auxiliary steam of the deaerator 16 is utilized, and circulates the internal water of the deaerator 16 to store the water storage tank 18. The water temperature is made uniform.

  The deaerator 16 is provided with a recirculation system 20 for circulating the water in the water storage tank 18, and the recirculation system 20 is provided with a recirculation flow rate control valve 22. The recirculation system 20 is for ensuring the necessary minimum flow rate of the water supply pump 24 of the water supply system 23. Since the feed water pump 24 cannot operate below the required minimum flow rate, when the feed water flow rate supplied to the boiler 11 through the feed water control valve 25 and the feed water stop valve 26 is small, the feed water pump 24 discharges from the feed water pump 24 to ensure the required minimum flow rate. The operation is performed by circulating the supplied water flow rate to the recirculation system 20. The recirculation flow rate control valve 22 adjusts the circulation flow rate at that time.

  When the boiler starter 27 starts up the boiler 11 and the auxiliary steam is supplied to the deaerator 16, the boiler feed device 27 discharges the feed water flow from the feed water pump 24 in order to ensure the necessary minimum flow rate of the feed water pump 24. Is operated in the normal mode in which the refrigerant is circulated through the recirculation system 20. On the other hand, when the auxiliary steam is not supplied to the deaerator 16, the water in the water storage tank 18 is circulated by the water supply pump 24 to the recirculation system 20 by the water supply pump 24, and the temperature of the water in the water storage tank 18 is dissolved oxygen. A temperature increase mode operation is performed in which the temperature of the water in the water storage tank 18 is increased so as to reach a predetermined temperature that satisfies the specified concentration value. Thereby, the boiler starting device 27 can obtain water satisfying the specified value of the dissolved oxygen concentration even when there is no auxiliary steam to the deaerator, and supplies the water to the boiler 11 to supply the boiler 11. Can be activated.

  The boiler start command is input to the recirculation system operation means 28 and the auxiliary steam determination means 30 of the boiler starter 27. When the auxiliary steam determination means 30 inputs the boiler start command, the temperature of the water in the water storage tank 18 is input from the temperature detector 29 that detects the temperature of the water in the water storage tank 18, and there is auxiliary steam to the deaerator 16. Determine whether or not. Whether or not there is auxiliary steam to the deaerator 16 is determined by whether or not the temperature of the water in the water storage tank 18 is equal to or higher than a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration. When the temperature of the water in the water storage tank 18 is equal to or higher than a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration, it is determined that there is auxiliary steam to the deaerator 16, and when that is not the case, auxiliary steam to the deaerator 16 is determined. Judge that there is no.

  The determination result of the auxiliary steam determination unit 30 is input to the recirculation system operation unit 28. When the recirculation system operation means 28 inputs the boiler start command, the recirculation system operation means 28 refers to the determination result of the auxiliary steam determination means 30, and performs normal mode operation when it is determined that there is auxiliary steam to the deaerator 16. . In the normal mode operation, when the feed water flow rate supplied to the boiler 11 is small, a part of the discharge flow rate of the feed water pump 24 is circulated to the recirculation system 20 of the deaerator 16 while ensuring the necessary minimum flow rate of the feed water pump 24. When the feed water is supplied to the boiler 11 and the flow rate of the feed water supplied to the boiler 11 is increased, the circulation of the recirculation system 20 is stopped.

  On the other hand, when the determination result of the auxiliary steam determination means 30 is a determination result that there is no auxiliary steam to the deaerator 16, the water supply control valve 25 and the water supply stop valve 26 of the water supply system 23 are fully closed, and the recirculation system The recirculation flow rate control valve 20 is fully opened, the feed water pump 24 is started, and the temperature raising mode operation is performed in which the water in the water storage tank 18 is circulated through the recirculation system 20. Thereby, the water in the water storage tank 18 of the deaerator 11 is circulated to the recirculation system 20, and the temperature of the water in the water storage tank 18 gradually increases. This is because when the water in the water storage tank 18 of the deaerator 11 is circulated through the recirculation system 20, the circulating water gradually rises in temperature due to frictional heat between the water and the blades of the water supply pump 24 and the inner surface of the pipe.

  Next, the feed water flow rate adjusting means 31 inputs the temperature of the water in the water storage tank 18 from the temperature detector 29, and determines whether or not the temperature of the water in the water storage tank 18 has reached a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration. judge. When the temperature of the water in the water storage tank 18 reaches a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration, the water supply stop valve 26 is opened, the opening degree of the water supply control valve 25 is adjusted, and water supply to the boiler 11 is started.

  For example, when the temperature of the water in the water storage tank 18 is 100 ° C. or higher, the dissolved oxygen concentration is 50 ppb or lower, which is a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration. Therefore, water supply to the boiler 11 is started when the temperature of the water in the water storage tank 18 is 110 ° C. or more in anticipation of safety. Thereby, boiler water filling is performed. In this case, since the temperature of the water in the water storage tank 18 decreases when the water supply flow rate per hour is large, the amount of water filling per hour is set to an amount smaller than that in the normal mode operation.

  That is, the water supply flow rate adjusting means 31 supplies water to the boiler 11 while monitoring the temperature of the water in the water storage tank 18 and adjusting the water supply flow rate so that the temperature of the water in the water storage tank 18 does not fall below a predetermined limit value. Supply. For example, the feed water flow rate is adjusted to maintain a feed water temperature of 110 ° C. or higher. Thereby, the dissolved oxygen concentration of the feed water to the boiler 11 can ensure 50ppb or less.

  When the water filling of the boiler 11 is completed, the burner is ignited by a boiler ignition device (not shown). Thereby, steam begins to be generated from the boiler 11. The pressure of the auxiliary steam supplied from the boiler 11 to the auxiliary steam pipe 32 is detected by the auxiliary steam pressure detector 33 and input to the auxiliary steam supply means 34.

  The auxiliary steam supply means 34 monitors the pressure of the auxiliary steam detected by the auxiliary steam pressure detector 33, and when the auxiliary steam is supplied to the deaerator 16 from the boiler 11, the auxiliary steam is It is determined that it has been established, and the auxiliary steam pressure control valve 19 is controlled to start supplying auxiliary steam to the deaerator 16. At the same time, a stop command for the temperature increase mode operation of the recirculation system 20 is output to the recirculation system operation means 28. When the recirculation system operation means 28 inputs a stop command for the temperature increase mode operation from the auxiliary steam supply means 34, the recirculation system operation means 28 shifts to the normal operation mode, and the recirculation flow rate control valve 19 of the recirculation system 20 of the deaerator 16 is set to the feed pump The routine shifts to normal control for securing the necessary minimum flow rate of 24.

  FIG. 2 is a graph of the water temperature T and the dissolved oxygen concentration DO in the water storage tank 18 when the boiler starter according to the embodiment of the present invention is started in a thermal power plant. In FIG. 2, the characteristic at the time of starting the recirculation system 20 of the deaerator 16 at the time t1 in a certain thermal power plant is shown.

  At the time t1 when the recirculation system 20 of the deaerator 16 is activated, the temperature T of the water in the water storage tank 18 is 32 ° C. and the dissolved oxygen concentration DO is 7400 ppb, and the activation of the recirculation system 20 of the deaerator 16 is continued. In this state, at time t2 after about 13 hours, the temperature T of the water in the water storage tank 18 was about 150 ° C., and the dissolved oxygen concentration DO of the water in the water storage tank 18 was 10 ppb. It was confirmed that the temperature T of the water in the water storage tank 18 on the way was 110 ° C., and the dissolved oxygen concentration DO was 50 ppb or less.

  From this demonstration result, it is understood that when the water in the water storage tank 18 is circulated in the recirculation system 20 of the deaerator 16 over about 13 hours, the specified value of the dissolved oxygen concentration that can be supplied to the boiler 11 is sufficiently satisfied. It was. Therefore, it is possible to obtain water supply having a dissolved oxygen concentration that can be supplied to the boiler 11 without requiring an auxiliary steam source. Further, by simultaneously using a deoxygenating chemical such as hydrazine, the dissolved oxygen concentration can be lowered more effectively.

  FIG. 3 is a flowchart showing a boiler starting method according to the embodiment of the present invention. First, it is determined whether or not there is an activation command for the boiler 11 (S1). If there is an activation command for the boiler 11, it is determined whether or not there is auxiliary steam (S2). When there is auxiliary steam, normal mode operation is performed (S3). That is, when the feed water flow rate supplied to the boiler 11 is small, a part of the discharge flow rate of the feed water pump 24 is circulated to the recirculation system 20 of the deaerator 16 to ensure the necessary minimum flow rate of the feed water pump 24 and to the boiler 11. When water supply is supplied and the flow rate of water supplied to the boiler 11 increases, an operation for stopping the circulation of the recirculation system 20 is performed.

  On the other hand, when there is no auxiliary steam, a heating mode operation is performed in which the water in the water storage tank 18 is circulated through the recirculation system 20 of the deaerator (S4). Then, it is determined whether or not the temperature of the water in the water storage tank 18 has reached a predetermined temperature (S5). The predetermined temperature is determined based on whether or not the dissolved oxygen concentration DO of the water in the water storage tank 18 satisfies a specified value (for example, 50 ppb or less) of the dissolved oxygen concentration that can be supplied to the boiler 11. For example, the determination is made based on whether or not the temperature is 100 ° C. or higher. In consideration of safety, the temperature may be 110 ° C. or 150 ° C.

  When the temperature of the water in the water storage tank 18 reaches a predetermined temperature, the water supply stop valve 26 is opened, the opening degree of the water supply control valve 25 is adjusted, and water supply to the boiler 11 is started (S6). In that case, feed water is supplied to the boiler 11 while adjusting the feed water flow rate so that the temperature of the water in the water storage tank 18 does not fall below a predetermined limit value (S7). This is to prevent the temperature of the water in the water storage tank 18 from being lowered when the feed water flow rate is rapidly increased, and to be less than or equal to the temperature that satisfies the specified value of the dissolved oxygen concentration that can be supplied to the boiler 11.

  Thereafter, when the water filling of the boiler 11 is completed, the boiler is ignited (S8). Thereby, since steam begins to be generated from the boiler 11, it is determined whether or not the auxiliary steam from the boiler 11 has been established (S9), and the auxiliary steam is established and the auxiliary steam can be supplied to the deaerator 16. Then, auxiliary steam is supplied from the boiler 11 to the deaerator 16 (S10). And it transfers to normal mode driving | operation from temperature rising mode driving | operation (S11).

  According to the embodiment of the present invention, the water in the water storage tank 18 of the deaerator 16 is circulated by the temperature rising mode operation using the recirculation system 20 of the deaerator 16, and the water supply pump 24 and the inner surface of the pipe are circulated. The temperature of circulating water is raised using frictional heat generated by resistance. And since the dissolved oxygen concentration in the water also reduces with the temperature rise of the water of the water storage tank 18, the auxiliary | assistant steam for raising water supply temperature is not required. Therefore, it is possible to obtain water supply to the boiler 11 that satisfies the specified value of the dissolved oxygen concentration regardless of the presence or absence of the steam source. In that case, since additional equipment for obtaining water supply to the boiler 11 that satisfies the specified value of the dissolved oxygen concentration is not required, the cost can be reduced.

DESCRIPTION OF SYMBOLS 11 ... Boiler, 12 ... Steam turbine, 13 ... Generator, 14 ... Condenser, 15 ... Condensate pump, 16 ... Deaerator, 17 ... Deaeration chamber, 18 ... Water storage tank, 19 ... Auxiliary steam pressure control valve , 20 ... Recirculation system, 21 ... Recirculation pump, 22 ... Recirculation flow rate control valve, 23 ... Feed water system, 24 ... Feed water pump, 25 ... Feed water stop valve, 26 ... Feed water control valve, 27 ... Boiler starter, 28 ... recirculation system operation means, 29 ... temperature detector, 30 ... auxiliary steam determination means, 31 ... feed water flow rate adjustment means, 32 ... auxiliary steam pipe, 33 ... auxiliary steam pressure detector, 34 ... auxiliary steam supply means

Claims (2)

Auxiliary steam determination means for determining whether there is auxiliary steam to the deaerator when a boiler activation command is issued;
When it is determined by the auxiliary steam determination means that there is auxiliary steam to the deaerator, a part of the discharge flow rate of the feed water pump is circulated to the recirculation system of the deaerator and the minimum required flow rate of the feed water pump Normal mode operation is performed, and when it is determined that there is no supply of auxiliary steam to the deaerator, the water in the water tank of the deaerator is circulated to the recirculation system to circulate the water in the water tank. Recirculation system operation means for switching from the temperature increase mode operation to the normal mode operation when auxiliary steam from the boiler to the deaerator is established,
When the temperature of the water in the water storage tank reaches a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration in the temperature rising mode operation by the recirculation system operation means, the boiler starts to supply water and the temperature of the water in the water storage tank Water supply flow rate adjusting means for supplying water to the boiler while adjusting the water supply flow rate so as not to be less than or equal to a predetermined limit value;
A boiler starter comprising: auxiliary steam supply means for supplying auxiliary steam to the deaerator when auxiliary steam from the boiler is established after water filling and ignition of the boiler. Determine if there is auxiliary steam to the deaerator when the boiler starts
Normal mode operation in which when it is determined that there is auxiliary steam to the deaerator, a part of the discharge flow rate of the feed water pump is circulated to the recirculation system of the deaerator to ensure the necessary minimum flow rate of the feed water pump And
When it is determined that there is no supply of auxiliary steam to the deaerator, the temperature raising mode of raising the temperature of the water in the water storage tank by circulating the water in the water tank in the deaerator to the recirculation system Drive,
When the temperature of the water in the water storage tank reaches a predetermined temperature that satisfies the specified value of the dissolved oxygen concentration, water supply to the boiler is started,
Supplying water to the boiler while adjusting the flow rate of water supplied to the boiler so that the temperature of the water in the water storage tank does not fall below a predetermined limit value;
When auxiliary steam from the boiler is established after water filling and ignition of the boiler, supply auxiliary steam to the deaerator,
A boiler start-up method, wherein the temperature rising mode operation is shifted to the normal mode operation.

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