JPH1047014A - High temperature cooling water system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability and thermal efficiency by a method wherein, in a pressure fluidized bed composition generating plant, high temperature cooling water necessary for prevention of the occurrence of acid dew point corrosion and ash fixing is always ensured and stably fed. SOLUTION: Feed water in a deaerator 19 is fed to a high temperature cooling water tank 26 through a high temperature cooling water tank water level regulating valve 25. After the feed water is boosted by a high temperature cooling water pump 27 and heat-exchanged (or heated) by a filter ash cooler 12, it is returned to the high temperature cooling water tank 26 through a pressure regulation valve 28. Quantities of exchange heat of various coolers 10, 11, and 12 are flashed in the tank 26 and recovered to a low pressure feed water heater 18 through a pressure regulation valve 29. During the stop of starting, feed water is fed from a steam generating device 22 to a deaerator 19 through a deaerator pressure regulating valve 23 to produce high temperature cooling water, from which a necessary temperature is ensured. Thereby, the high temperature cooling water is necessary to prevention of acid dew point corrosion and high temperature cooling water for cooling ash in exhaust gas and heating an apparatus is stably fed and heat is recovered in a cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature cooling water system, and more particularly to a high-temperature cooling water system suitable for a pressurized fluidized-bed combined power generation plant including a pressurized fluidized-bed boiler, a gas turbine, and a steam turbine.

[0002]

2. Description of the Related Art A conventional example of this type of pressurized fluidized bed combined cycle power plant will be described with reference to a schematic system diagram shown in FIG. In FIG. 6, a water level control valve 25 is provided between the high-temperature cooling water tank 26 and the deaerator 19 to control the water level in the high-temperature cooling water tank 26. The water level in the tank 26 is detected by a water level detector 31. The supply of water to the high-temperature cooling water tank 26 is pressurized by the high-temperature cooling water pump 27, and is supplied to various gas coolers 35 and 36.
After the heat exchange in the deaerator 1 is recovered to the high-temperature cooling water tank 26 through the cooling water pressure control valve 28 and is used as flash steam.
9, heat is recovered.

[0003]

In such a conventional method, since the internal pressure of the deaerator 19 becomes low when the plant is started and stopped, high-temperature water required as high-temperature cooling water is supplied. Becomes impossible. In particular, since there is no heat input from the various coolers 35 and 36 at the time of startup, the temperature in the high-temperature cooling water tank becomes normal temperature (20 ° C.). In addition, during a transition of the plant, the internal pressure of the deaerator 19 rapidly decreases, so that the internal pressure of the high-temperature cooling water tank 26 also rapidly decreases. As a result, it is easily presumed that the accumulated water is flushed between the high-temperature cooling water tank 26 and the high-temperature cooling water pump 27 and the high-temperature cooling water pump 27 is stopped.

Further, as shown in FIG. 5, when used for various gas coolers 35 and 36 and cooling water for heating, since the internal pressure of the deaerator 19 rises with an increase in load, the cooling water temperature of the high-temperature cooling water increases. Becomes high temperature, various gas coolers 35, 3
6, and the equipment cost of the high-temperature cooling water pump 27 and the in-plant power (pump shaft power) are greatly increased.

In the apparatus disclosed in Japanese Patent Application Laid-Open No. 6-288201, a cooler is connected in parallel and directly connected to the deaerator. It was difficult to ensure the required minimum temperature of the water.

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems of the prior art. In a plant such as a combined pressurized fluidized-bed power plant equipped with a pressurized fluidized-bed boiler, a gas turbine, a steam turbine, and the like, An object of the present invention is to provide a high-temperature cooling water system with improved reliability and thermal efficiency at the time of start-up, normal, and transition of a plant.

[0007]

Means for solving the above problem will be described below with reference to FIGS. A first aspect of the present invention provides a boiler (furnace 1, pressure vessel 2) such as a pressurized fluidized bed, a gas turbine 5 (FIG. 4) using exhaust gas supplied from the boiler, and steam generated in the boiler (furnace 1). , A condensate pump 17 and a water supply pump 20 for supplying water from the condenser 16 to the boiler (furnace 1), feed water heaters 18 and 21 for heating the feed water, and a deaerator. In a plant such as a pressurized fluidized-bed combined power generation plant comprising 19 or the like, high-temperature cooling water for cooling gas and ash in a boiler and an exhaust gas system such as a pressurized fluidized bed or for heating exhaust gas equipment is deaerated. A high-temperature cooling water tank 26, a high-temperature cooling water pump 27, pipes, valves, and the like are provided for supplying heat from the heat source 19 and recovering heat to the feedwater heater 18. Thereby, the supply water of the high-temperature cooling water tank 26 is pressurized by the high-temperature cooling water pump 27, and various ash coolers 10, 11, 12 and heating devices (devices installed in the exhaust gas system (cyclone 3, filter 4 ) And pipes (pipes between the cyclone 3 and the cyclone ash cooler 11, pipes between the filter 4 and the filter ash cooler 11)), and are collected in the high-temperature cooling water tank 26 and sent to the feed water heater 18 as flash steam. Heat can be recovered. Further, the invention according to claim 2 is for adjusting the amount of replenishing water to the high-temperature cooling water tank 26 based on a signal from the high-temperature cooling water tank water level detector 31 (FIG. 2) in a pressurized fluidized bed combined cycle power plant or the like. The high-temperature cooling water tank water level control valve 25 and the high-temperature cooling water return water pressure for cooling the exhaust gas and ash or for heating the exhaust gas system equipment are determined by a signal from the high-temperature cooling water return water pressure detector 33 (FIG. 2). A cooling water pressure control valve 28 for adjustment and a high temperature cooling water tank 26
A high temperature cooling water tank pressure control valve 29 for adjusting the internal pressure by a signal from the high temperature cooling water tank pressure detector 32 is provided. Thus, during a transition, the high-temperature cooling water tank pressure control valve 29 is controlled by the high-temperature cooling water tank pressure signal.
, The internal pressure of the high-temperature cooling water tank 26 is controlled, so that even when the internal pressure of the deaerator 19 suddenly decreases, the accumulated water between the high-temperature cooling water tank 26 and the high-temperature cooling water pump 27 may be flushed. As a result, a stable operation state can be secured. Further, according to the third aspect of the present invention, in a pressurized fluidized bed combined cycle power plant or the like, a steam supply means 22 (in-house boiler or other can steam or the like) for adjusting the pressure (temperature) of the deaerator 19 is provided. That is, a deaerator pressure regulating valve 23 for adjusting the internal pressure of the vessel 19 based on a signal from the deaerator pressure detector 24, piping and valves are provided. At the time of startup, since there is no heat input from the various coolers 35 and 36, the temperature in the high-temperature cooling water tank has dropped to room temperature (20 ° C.). The internal pressure 19 can be raised to a temperature required for the high-temperature cooling water by the deaerator pressure control valve 23. Therefore, it is possible to secure high-temperature cooling water from the start-up, and it is possible to prevent acid dew point corrosion and ash adhesion. In acid dew point corrosion, the SO _{3 component} and the H ₂ O component in the exhaust gas react with each other to form acidic ammonium sulfate, which adheres to the heat exchanger and equipment, and the performance of the heat exchanger deteriorates and corrosion proceeds. The ash becomes a solid by the reaction with H ₂ O. For this reason, the heat exchanger and the piping of the exhaust gas system require high-temperature cooling water. In the pressurized fluidized bed combined cycle power plant and the like, the high-temperature cooling water is supplied from the high-temperature cooling water tank 26 or the pipe section to the condenser 16, the feedwater heaters 18, 21, the deaerator 1 and the like.
9. A condensate pipe from the condensate pump 17 to the deaerator 19 or a pipe and a valve for blowing outside the system are provided. Thereby, at the time of startup, hot water can be introduced from the deaerator into the system instead of cold water. Also, in the invention of claim 5, in a pressurized fluidized bed combined cycle power plant or the like, the high-temperature cooling water is supplied from the deaerator 19, and after being pressurized by the high-temperature cooling water pump 27, the various coolers 10, 11,
In other words, a pipe and a valve for recovering the low-temperature exhaust heat recovery means 7 to the inlet condenser through the condenser 12 are provided. Thus, when the startup is stopped, the high-temperature cooling water is supplied by supplying the steam from the steam supply device 22 to the deaerator 19 via the deaerator pressure control valve 23 in accordance with a signal from the deaerator pressure detector 24. The required cooling water temperature is secured.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 show an embodiment of the present invention, and the same elements as those shown in FIG. 6 are denoted by the same reference numerals, and redundant description will be omitted. First, as shown in FIG. 4, according to the present embodiment, after removing high-temperature combustion gas from the furnace 1 in the pressure vessel 2 through the cyclone 3 and the filter 4 to remove ash and the like in the combustion gas, The gas is supplied to the gas turbine 5, and the gas turbine generator 9 is driven to generate power. Further, the exhaust gas of the gas turbine 5 is recovered into the steam turbine system by the high-temperature exhaust heat recovery device 6 and the low-temperature exhaust heat recovery device 7, and then is discharged from the chimney 8 to the atmosphere. Furnace 1
In the exhaust gas system from to the gas turbine 5, a furnace bottom ash cooler 10, a cyclone ash cooler 11, and a filter ash cooler 12 are provided in order to recover the heat of the ash removed by the furnace 1, the cyclone 3, and the filter 4. In particular, cooling water for cooling gas and ash in exhaust gas and for warming equipment requires high-temperature cooling water from the viewpoint of preventing acid dew point corrosion and preventing ash sticking.

As shown in FIG. 1, the steam generated in the furnace 1 is supplied to a condenser 16 through a high-pressure turbine 13 and a low-pressure turbine 14, and drives a steam turbine generator 15 to generate electricity. The condensed water condensed in the condenser 16 is pressurized by the condensate pump 17, is heated by the low-pressure feed water heater 18 and the low-temperature exhaust heat recovery device 7, and is supplied to the deaerator 19.
Water (condensate) supplied to the deaerator 19 is supplied to the water supply pump 2
The pressure is increased at 0, and the temperature is increased by the high-pressure feed water heater 21 and the high-temperature exhaust heat recovery device 6, and then supplied to the furnace 1 again.

The supply water in the deaerator 19 is supplied to a high-temperature cooling water tank 26 via a high-temperature cooling water tank water level control valve 25. The high-temperature cooling water (supply water) supplied to the high-temperature cooling water tank 26 is pressurized by the high-temperature cooling water pump 27 and heat-exchanged (or heated) by the furnace bottom ash cooler 10, the cyclone ash cooler 11, and the filter ash cooler 12. Thereafter, the cooling water is returned to the high-temperature cooling water tank 26 via the cooling water pressure control valve 28, and the exchanged heat of the various coolers 10, 11, and 12 is flushed in the high-temperature cooling water tank 26, and the high-temperature cooling water tank pressure control valve 29 After being condensed and condensed and exchanged heat, the pressure is increased by a drain pump 38 and collected in a condensate pipe.

As shown in detail in FIG. 2, a high-temperature cooling water tank water level adjusting valve 25 for adjusting the amount of replenishment water to the high-temperature cooling water tank 26 based on a signal from the high-temperature cooling water tank water level detector 31, A cooling water pressure control valve 28 for adjusting the pressure of the high temperature cooling water return water for cooling the ash or heating the exhaust gas system equipment by a signal from the high temperature cooling water return water pressure detector 33, and a high temperature cooling water tank A high-temperature cooling water tank pressure control valve 29 for adjusting the internal pressure of the tank 26 by a signal from the high-temperature cooling water tank pressure detector 32 is provided.

That is, the high-temperature cooling water recovered by the various coolers 10, 11 and 12 is recovered in the high-temperature cooling water tank, and the internal pressure of the high-temperature cooling water tank is determined by the pressure signal from the high-temperature cooling water tank pressure detector 32. Thus, the internal pressure of the high-temperature cooling water tank 26 is controlled to be constant by the high-temperature cooling water tank pressure control valve 29, so that the flash steam for the heat recovery is supplied to the low-pressure feed water heater 18 through the high-temperature cooling water tank pressure control valve 29. Supplied to For this reason, the water level of the high-temperature cooling water tank 26 decreases (for the amount of flash steam), and the high-temperature cooling water tank water level control valve 25 is opened by a signal from the high-temperature cooling water tank level detector 31, and the deaerator 19 Deaerator 19 to high-temperature cooling water tank 26 via high-temperature cooling water tank water level control valve 25
The water supply inside is supplied.

According to the above, during normal operation, the high-temperature cooling water level control valve 25 is disposed between the high-temperature cooling water tank 26 and the deaerator 19.
To control the water level of the high-temperature cooling water tank 26,
The supply water of the high-temperature cooling water tank 26 is pressurized by the high-temperature cooling water pump 27, and various ash coolers 10, 11, 12 and heating devices (devices such as the cyclone 3 and the filter 4 installed in the exhaust gas system). And between the cyclone 3 and the cyclone ash cooler 11 and the pipe between the filter 4 and the filter ash cooler 11), is collected in the high-temperature cooling water tank 26, and is transferred to the feed water heater 18 as flash steam. It can be recovered.

Also, at the time of starting and stopping, since there is no bleeding to the deaerator 19 (the bleeding stop valve 39 is fully opened), the pressure (temperature) in the deaerator is low, and the required temperature as high-temperature cooling water cannot be secured. Therefore, the deaerator pressure control valve 2 is supplied from the steam supply device 22.
Steam is supplied to the deaerator 19 via the signal from the deaerator pressure detector 24 via 3 and the condensate flowing into the deaerator is heated to secure the required cooling water temperature as the high-temperature cooling water. Is done.

Therefore, at the time of starting and stopping, the steam generator 2
The steam from 2 makes it possible to raise the internal pressure of the deaerator 19 to the temperature required for the high-temperature cooling water by the deaerator pressure regulating valve 23, so that the high-temperature cooling water can be secured from the start, and the acid dew point To prevent corrosion and ash sticking. (Acid dew point corrosion is a phenomenon in which SO ₃ and H ₂ O in exhaust gas react with each other to form acidic ammonium sulfate, which adheres to heat exchangers and equipment to reduce the performance of the heat exchanger and Corrosion progresses, and the ash and H ₂ O react to form a solid, so that the exhaust gas heat exchanger and piping require high-temperature cooling water.) Further, in an operation state in which there is no heat input from the various ash coolers 10, 11, 12 and the heating device, the high-temperature cooling water is supplied from the high-temperature cooling water tank 26 or the pipe section to the condenser 1
By providing a cooling water temperature control valve 30 that operates at a high temperature cooling water return water temperature in the piping 6 for blowing to the outside of the system, or the feed water heaters 18 and 21, the deaerator 19, The required cooling water temperature can be secured.

Further, in an operation state in which heat is not recovered from the various coolers 10, 11, and 12, the condenser 16 is connected via a pipe branched from a cooler outlet pipe and a temperature control valve 30.
Alternatively, by collecting a part or the entire amount of the high-temperature cooling water into the condenser pipe, the cooling water temperature required as the high-temperature cooling water is secured. That is, by collecting a part or the entire amount of the high-temperature cooling water into the condenser 16, the water level of the high-temperature cooling water tank 26 decreases. The water level control valve 25 is opened, and the supply water of the deaerator 19 is supplied to the high temperature cooling water tank 26 via the high temperature cooling water tank water level control valve 25.

The high-temperature cooling water collected in the condenser 16 is boosted in pressure by the condenser pump 17, heated in the low-temperature feed water heater 18 and the low-temperature waste heat recovery device 7, and then supplied to the deaerator 19. Then, the steam from the steam supply device 22 is heated to a temperature required as high-temperature cooling water, and the high-temperature cooling water tank 26
Supplied to

In the transient state, even if the internal pressure of the deaerator 19 drops rapidly, the signal from the high-temperature cooling water tank pressure detector 32 detects the high temperature of the high-temperature cooling water tank pressure control valve 29. Since the cooling water tank pressure is controlled to be constant, the high temperature cooling water pump 27
The accumulated water does not flush until then, and stable operation is possible.

FIG. 3 shows another embodiment of the present invention. According to the present embodiment, high-temperature cooling water for cooling the gas and ash of the exhaust gas system or for heating the equipment is supplied from the deaerator 19,
After the pressure is raised by the high-temperature cooling water pump 27, the various coolers 10, 1
It is recovered to the inlet condensate pipe of the low-temperature exhaust heat recovery device via 1 and 12. For this reason, when the start-up is stopped, the steam from the steam supply device 22 is supplied to the deaerator 19 via the deaerator pressure control valve 23 by a signal from the deaerator pressure detector 24, so that the high-temperature cooling water is supplied. The required cooling water temperature is secured.

FIG. 5 shows the pressure and temperature characteristics of the deaerator 19, the high-temperature cooling water tank 26, and the low-pressure feed water heater 18 at each load. As shown in this figure, about 40
% Load or more, the internal pressure of the deaerator 19 is
Since the internal pressure is higher than 6, the supply water in the deaerator 19 can be supplied to the high-temperature cooling water tank 26 stably. Further, since the internal pressure of the high-temperature cooling water tank 26 is higher than the internal pressure of the low-pressure water heater 18, the flash steam in the high-temperature cooling water tank 26 can be stably recovered to the low-pressure water heater 18. On the other hand, about 4
At a load of 0% or less, the internal pressure (temperature) of the deaerator 19 can be adjusted by the steam from the steam supply device 22, so that a stable operation equivalent to about 40% load or more is possible.

As described above, according to the embodiment of the present invention, in the pressurized fluidized-bed combined power generation plant including the pressurized fluidized-bed boiler, the gas turbine, the steam turbine, and the like, when the plant starts and stops, during normal operation, and during transient operation, Occasionally, high-temperature cooling water required for cooling gas and ash in exhaust gas, preventing acid dew point corrosion required as heating water for exhaust gas equipment, and preventing ash sticking is secured, improving reliability and improving thermal efficiency. The effect is obtained for improvement. In addition, in equipment and in-house power, the internal pressure of the high-temperature cooling water tank is controlled by a control valve in comparison with the conventional method (that is, the high-temperature cooling water increases with an increase in load). Can be temperature. Therefore, the cooling area of the cyclone ash cooler, the filter ash cooler, and the like can be reduced.
Further, the power of the high-temperature cooling water pump is smaller than that of the conventional method in terms of internal power, which is effective in reducing the power of the high-temperature cooling water pump. Since the high-temperature cooling water pump head is determined by the saturation pressure of each cooler outlet temperature (prevention of flushing at the cooler outlet), the lower the temperature in the high-temperature cooling water tank 26, the smaller the pump head.

[0022]

As described above, according to the present invention, in a plant such as a pressurized fluidized-bed combined power generation system including a pressurized fluidized-bed boiler, a gas turbine, a steam turbine, and the like, when the plant is started or stopped, during normal operation, In addition, the reliability and thermal efficiency at the time of transition can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of an embodiment of the present invention.

FIG. 2 is a detailed system diagram of one embodiment of the present invention.

FIG. 3 is a detailed system diagram of another embodiment of the present invention.

FIG. 4 is an overall system diagram of an exhaust gas system in a pressurized fluidized-bed boiler.

FIG. 5 is a pressure-temperature characteristic diagram of each load in one embodiment of the present invention.

FIG. 6 is a schematic system diagram of a conventional pressurized fluidized bed combined cycle power plant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace 2 Pressure vessel 3 Cyclone 4 Filter 5 Gas turbine 6 High temperature exhaust heat recovery device 7 Low temperature exhaust heat recovery device 8 Chimney 10 Furnace low ash cooler 11 Cyclone ash cooler 12 Filter ash cooler 13 High pressure turbine 14 Low pressure turbine 16 Condenser 17 Condenser pump 18 Low pressure feed water heater 19 Deaerator 20 Feed pump 21 High temperature feed water heater 22 Steam generator 22 Deaerator pressure control valve 25 High temperature cooling water tank water level control valve 26 High temperature cooling water tank 27 High temperature cooling water pump 28 Cooling water pressure control valve 29 High temperature cooling water tank pressure control valve 37 Circulation pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Asao 3-2-1 Sachimachi, Hitachi-shi, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (72) Inventor Shinichiro Tsuchida 3-2-2 Sachimachi, Hitachi-shi, Ibaraki No. 1 Inside Hitachi Engineering Co., Ltd.

Claims (5)

[Claims] 1. A pressurized fluidized bed boiler, a gas turbine driven by a combustion gas supplied from the pressurized fluidized bed boiler through an exhaust gas system, and a steam turbine driven by steam generated in the pressurized fluidized bed boiler A condensate pump and a water supply pump for supplying water to the pressurized fluidized-bed boiler from a condenser, a feedwater heater for heating the feedwater, a deaerator, and the like. In the high-temperature cooling water system in the plant, the high-temperature cooling water for cooling the gas or ash of the pressurized fluidized-bed boiler and the exhaust gas system or for heating the exhaust gas system equipment is supplied from the deaerator to heat the feedwater. A high-temperature cooling water system comprising a high-temperature cooling water tank, a pump, and a piping valve for recovering heat to a vessel. 2. The high-temperature cooling water system according to claim 1, wherein a water level control valve for adjusting a replenishing water amount to the high-temperature cooling water tank based on a water level signal of the high-temperature cooling water tank, and return water of the high-temperature cooling water. A high-temperature cooling water system comprising a pressure adjusting valve for adjusting pressure and a pressure adjusting valve for adjusting the internal pressure of the high-temperature cooling water tank. 3. The high-temperature cooling water system according to claim 1, further comprising a steam supply means such as an in-house boiler or another can steam for adjusting the pressure or the temperature of the deaerator, wherein the steam supply means and the steam supply means are provided. A high-temperature cooling water system, wherein a pressure control valve for adjusting the internal pressure of the deaerator is provided in a pipe between the deaerator and the pipe. 4. The high-temperature cooling water system according to claim 1, wherein the high-temperature cooling water is removed from a condenser, a feed water heater, a deaerator, and a condensate pump from the high-temperature cooling water tank or its piping. A high-temperature cooling water system provided with a condensate pipe to the gastrointestinal tract or a pipe and a valve for blowing out of the system. 5. The high-temperature cooling water system according to claim 1, wherein the high-temperature cooling water is supplied from a deaerator, is pressurized by a pump, and is recovered to a condensate pipe at an inlet of an exhaust heat recovery means through various coolers. A high-temperature cooling water system characterized by providing a piping and a valve to perform cooling.