Invention name: Exhaust gas cooler
Technical field
[0001]
　The present disclosure relates to an exhaust gas cooler for cooling exhaust gas.
Background technology
[0002]
　The exhaust gas cooler for cooling the exhaust gas is provided with an economizer that exchanges heat between the exhaust gas and the water supply. If the dew point temperature of the exhaust gas is high, the temperature of the exhaust gas may fall below the dew point temperature due to heat exchange in the economizer, and dew condensation may occur. In the case of corrosive exhaust gas, condensation on the exhaust gas can lead to corrosion of the economizer.
[0003]
　In the economizer described in Patent Document 1, the entire amount of water supplied to the water supply drum flows into the economizer and exchanges heat with the exhaust gas before flowing into the water supply drum, but before the water supply flows into the economizer, By mixing hot water from the air-water drum into the water supply and maintaining the temperature of the water supply flowing into the economizer at the set temperature, dew condensation on the exhaust gas is prevented.
Prior art literature
Patent documents
[0004]
Patent Document 1: Japanese Unexamined Patent Publication No. 2015-10798
Outline of the invention
Problems to be solved by the invention
[0005]
　However, in the economizer described in Patent Document 1, since the entire amount of water supplied to the brackish water drum flows into the economizer, if the amount of water supplied increases, it becomes difficult to maintain the set temperature by mixing hot water into the water supply, and dew condensation on the exhaust gas. May occur.
[0006]
　In view of the above circumstances, at least one embodiment of the present disclosure is an object of providing an exhaust gas cooler capable of suppressing dew condensation of exhaust gas in an economizer.
Means to solve problems
[0007]
　The exhaust gas cooler according to at least one embodiment of the present invention includes an economizer that exchanges heat between the exhaust gas and the first water, and a water supply pipe for supplying the second water having a temperature lower than that of the first water to the first water. The second water is separately supplied as the first water flowing out of the economizer and the first water flowing into the economizer.
[0008]
　According to this configuration, by supplying at least a part of the second water to the first water flowing into the economizer, the economizer is compared with the case where the entire amount of the second water is supplied to the first water flowing into the economizer. The temperature of the first water flowing into the water becomes high. Therefore, since the decrease in the exhaust gas temperature due to the heat exchange between the exhaust gas and the first water in the economizer is reduced, the dew condensation of the exhaust gas can be suppressed in the economizer.
[0009]
　In some embodiments, a temperature detection member that detects the inlet temperature, which is the temperature of the first water flowing into the economizer, and an inlet side supply, which is the supply amount of the second water supplied to the first water flowing into the economizer. An inlet side supply amount adjusting member for adjusting the amount is provided, and the inlet side supply amount adjusting member is configured to adjust the inlet side supply amount so that the inlet temperature is within a preset set temperature range. You may.
[0010]
　According to this configuration, by setting an appropriate set temperature range, the temperature of the exhaust gas can be maintained above the dew point temperature in the economizer, and the risk of boiling of the first water can be reduced.
[0011]
　In some embodiments, a steam drum into which the first water flowing out of the economizer flows is further provided, and a portion of the second water is supplied between the economizer and the steam drum to the first water flowing out of the economizer. You may. In this case, an exhaust heat boiler that heats the first water flowing into the steam drum to generate steam is further provided, and the exhaust gas heats with the first water in the exhaust heat boiler before exchanging heat with the first water in the economizer. You may replace it.
[0012]
　By supplying at least a part of the second water to the first water flowing into the economizer, the decrease in the exhaust gas temperature due to the heat exchange between the exhaust gas and the first water in the economizer is reduced, and the dew condensation of the exhaust gas in the economizer is suppressed. Although it can be done, the cooling effect of the exhaust gas deteriorates. However, according to this configuration, the exhaust gas is cooled by generating steam in the exhaust heat boiler before flowing into the economizer, so that the deterioration of the cooling effect of the exhaust gas can be suppressed by cooling in each of the exhaust heat boiler and the economizer. Can be done.
[0013]
　In some embodiments, the exhaust gas may be exhaust gas from a combustion furnace in an integrated coal gasification combined cycle plant. The exhaust gas from the combustion furnace in an integrated coal gasification combined cycle plant contains sulfur trioxide (SO 3 ), so the acid dew point is high. Therefore, the exhaust gas is likely to condense in the economizer. Condensation of exhaust gas containing SO 3 produces sulfuric acid, which leads to corrosion of the economizer. Therefore, the exhaust gas cooler of an integrated coal gasification combined cycle has an effect of suppressing dew condensation of exhaust gas in the economizer.
Effect of the invention
[0014]
　According to at least one embodiment of the present disclosure, the first water flowing into the economizer is supplied with at least a part of the second water, so that the first water flowing into the economizer is supplied with the entire amount of the second water. The temperature of the first water flowing into the economizer is higher than that in the case of Therefore, since the decrease in the exhaust gas temperature due to the heat exchange between the exhaust gas and the first water in the economizer is reduced, the dew condensation of the exhaust gas can be suppressed in the economizer.
A brief description of the drawing
[0015]
FIG. 1 is a schematic configuration diagram of an exhaust gas cooler according to a first embodiment of the present disclosure.
FIG. 2 is a schematic configuration diagram of an exhaust gas cooler according to a second embodiment of the present disclosure.
FIG. 3 is a graph showing an example of a change over time in the temperature of circulating water flowing into an economizer in the exhaust gas cooler according to the second embodiment of the present disclosure.
Mode for carrying out the invention
[0016]
　Hereinafter, some embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention only to them, but are merely explanatory examples.
[0017]
(Embodiment 1)
　The exhaust gas cooler of the present disclosure will be described by taking as an example equipment for cooling exhaust gas from a combustion furnace in an integrated coal gasification combined cycle plant. The exhaust gas cooler of the present disclosure is not limited to such equipment, and can be used for equipment for cooling exhaust gas discharged from any equipment.
[0018]
　As shown in FIG. 1, the exhaust gas cooler 1 according to the first embodiment of the present disclosure supplies the economizer 2 for heat exchange between the exhaust gas and the circulating water (first water) and the water supply (second water) to the circulating water. It is provided with a water supply pipe 3 (second water supply pipe) for the purpose. The water supply pipe 3 includes one main pipe 3a and two branch pipes whose ends are connected to the main pipe 3a so as to branch from the main pipe 3, that is, the upstream side branch pipe 3b and the downstream side branch pipe 3c. Includes. The other end of the upstream branch pipe 3b is connected to the pipe 11 on the upstream side of the economizer 2 in the circulation direction of the circulating water. The other end of the downstream branch pipe 3c is connected to the pipe 12 on the downstream side of the economizer 2 in the circulation direction of the circulating water.
[0019]
　When the exhaust gas cooler 1 is a facility for cooling the exhaust gas from the combustion furnace in the coal gasification combined power plant, the exhaust gas cooler 1 is connected to the economizer 2 via the pipe 12 via the steam drum 4 and the pipe 12. An exhaust heat boiler 5 that heats the circulating water that has flowed into the steam drum 4 to generate steam, and a pump 6 that supplies the water in the steam drum 4 as circulating water to the economizer 2 via the pipe 11 are further provided. There is. The exhaust heat boiler 5 is configured such that the exhaust gas before flowing into the economizer 2 generates steam by exchanging heat with the circulating water flowing into the steam drum 4.
[0020]
　Next, the operation of the exhaust gas cooler 1 according to the first embodiment will be described.
　The exhaust gas from the combustion furnace flows into the exhaust heat boiler 5, and steam is generated by heat exchange between the exhaust gas and the water in the steam drum 4 in the exhaust heat boiler 5 to heat the water, and steam is generated from the steam drum 4. Leaks out. On the other hand, water flows out from the steam drum 4 by the pump 6 and flows into the economizer 2 as circulating water through the pipe 11. The exhaust gas flowing out from the exhaust heat boiler 5 flows into the economizer 2, and the exhaust gas and the circulating water exchange heat in the economizer 2 to heat the circulating water. The circulating water heated in the economizer 2 flows into the steam drum 4 through the pipe 12.
[0021]
　Since steam flows out from the steam drum 4, it is necessary to supply the steam drum 4 with the same amount of water as the outflowed steam. The water supply is supplied to the circulating water through the water supply pipe 3 so as to flow out of the steam drum 4 and return to the steam drum 4 again. Generally, the temperature of the supplied water is lower than that of the circulating water. Therefore, if the entire amount of the supplied water is supplied to the circulating water flowing into the economizer 2, the temperature of the circulating water flowing into the economizer 2 drops significantly. Since the exhaust gas from the combustion furnace in the integrated coal gasification combined cycle plant contains SO 3 and has a high acid dew point, the temperature of the circulating water flowing into the economizer 2 is low, and the temperature of the exhaust gas rises due to heat exchange with the circulating water. If the temperature falls below the acid dew point, exhaust gas will condense in the economizer 2. Condensation of the exhaust gas containing SO 3 produces sulfuric acid, which leads to corrosion of the economizer 2.
[0022]
　On the other hand, when the entire amount of the supplied water is supplied to the circulating water flowing out from the economizer 2, the circulating water flowing out from the steam drum 4 flows into the economizer 2 as it is. Depending on the operating conditions of the integrated coal gasification combined cycle, the temperature and flow rate of the exhaust gas from the combustion furnace and the temperature of the circulating water may fluctuate. If the circulating water with a relatively high temperature flows into the economizer 2, or if the temperature of the exhaust gas flowing into the economizer 2 is high or the flow rate is large, the circulating water in the economizer 2 may be overheated and boil. .. Since the economizer 2 is often not designed on the premise that the circulating water boils, the economizer 2 may be damaged when the circulating water boils.
[0023]
　Therefore, in the first embodiment, the water supply is divided so as to flow through the main pipe 3a in the water supply pipe 3 and then through the upstream branch pipe 3b and the downstream branch pipe 3c, respectively, and the pipes 11 and 12 It is supplied to each of the circulating water that flows into each of the above and flows into the economizer 2 and the circulating water that flows out from the economizer 2. Here, assuming the normal operating conditions of an integrated coal gasification combined cycle plant, a certain range is estimated for each of the temperature and flow rate of the exhaust gas flowing into the economizer 2 and the temperature of the circulating water flowing out from the steam drum 4. be able to. Based on these ranges, the flow rate of the water supply flowing through the upstream branch pipe 3b, that is, the amount of the water supply supplied to the circulating water flowing into the economizer 2, is determined, so that the circulating water flowing into the economizer 2 is transferred to the economizer 2 The temperature can be adjusted to an appropriate level so that the exhaust gas does not condense and the circulating water does not boil.
[0024]
　In this way, by supplying at least a part of the water supply to the circulating water flowing into the economizer 2, the circulation flowing into the economizer 2 is compared with the case where the entire amount of the supplied water is supplied to the circulating water flowing into the economizer 2. The temperature of the water rises. Therefore, since the decrease in the exhaust gas temperature due to the heat exchange between the exhaust gas and the circulating water in the economizer 2 is reduced, the dew condensation of the exhaust gas can be suppressed in the economizer 2.
[0025]
　However, if at least a part of the water supply is supplied to the circulating water flowing into the economizer 2 to reduce the decrease in the exhaust gas temperature due to the heat exchange between the exhaust gas in the economizer 2 and the circulating water, the dew condensation of the exhaust gas in the economizer 2 will occur. Although it can be suppressed, the cooling effect of the exhaust gas deteriorates. However, in the first embodiment, since the exhaust gas is cooled by generating steam in the exhaust heat boiler 5 before flowing into the economizer 2, the cooling effect of the exhaust gas is deteriorated by the cooling in each of the exhaust heat boiler 5 and the economizer 2. Can be suppressed.
[0026]
(Embodiment 2)
　Next, the exhaust gas cooler according to the second embodiment will be described. The exhaust gas cooler according to the second embodiment is modified from the first embodiment so as to control the amount of water supplied to the circulating water so that the circulating water flowing into the economizer has a temperature within an appropriate range. Is. In the second embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.
[0027]
　As shown in FIG. 2, the pipe 11 has an inlet temperature which is the temperature of the circulating water flowing into the economizer 2 on the downstream side in the flow direction of the circulating water from the connection portion 11a between the upstream branch pipe 3b and the pipe 11. A temperature sensor 20 (temperature detection member) for detecting the above is provided. The upstream branch pipe 3b has a flow rate control valve 30 (inlet) for adjusting the inlet side supply amount, which is the supply amount of the supply water supplied to the circulating water flowing into the economizer 2, based on the value detected by the temperature sensor 20. A side supply amount adjusting member) is provided. Other configurations are the same as those in the first embodiment.
[0028]
　Next, the operation of the exhaust gas cooler 1 according to the second embodiment will be described.
　Also in the second embodiment, it is the same as the first embodiment that the economizer 2 can suppress the dew condensation of the exhaust gas by supplying at least a part of the water supply to the circulating water flowing into the economizer 2. The second embodiment is different from the first embodiment in that the supply amount of the supply water supplied to the circulating water flowing into the economizer 2 is adjusted based on the value detected by the temperature sensor 20. The differences from the first embodiment will be described below.
[0029]
　The opening degree of the flow rate control valve 30 is adjusted so that the value detected by the temperature sensor 20 is within the preset temperature range, so that the amount of water supplied through the upstream branch pipe 3b, that is, the economizer 2 is reached. It regulates the amount of water supplied to the inflowing circulating water. The set temperature range has an upper limit value and a lower limit value. When the value detected by the temperature sensor 20 exceeds the upper limit value, the amount of water supplied to the circulating water flowing into the economizer 2 increases by increasing the opening degree of the flow rate control valve 30, so that the water flows into the economizer 2. The temperature of the circulating water drops. On the other hand, if the value detected by the temperature sensor 20 falls below the lower limit value, the amount of water supplied to the circulating water flowing into the economizer 2 decreases by reducing the opening degree of the flow rate control valve 30, so that the economizer 2 can be used. The temperature of the inflowing circulating water increases.
[0030]
　As shown in FIG. 3, by such an operation, the value detected by the temperature sensor 20, that is, the temperature of the circulating water flowing into the economizer 2 is maintained between the upper limit value and the lower limit value of the set temperature range. become.
[0031]
　Here, the upper limit of the set temperature range is the maximum temperature for preventing the circulating water from boiling due to heat exchange with the exhaust gas in the economizer 2. On the other hand, the lower limit of the set temperature range is the minimum temperature at which the exhaust gas in the economizer 2 is prevented from condensing due to heat exchange with the circulating water. By appropriately setting the set temperature range in this way, the temperature of the exhaust gas can be maintained above the dew point temperature in the economizer 2, and the risk of boiling of circulating water can be reduced.
[0032]
　In the second embodiment, the flow rate control valve 30 is provided in the upstream branch pipe 3b, but may be provided in the downstream branch pipe 3c. Since the water supply flowing through the main pipe 3a is divided into each of the upstream side branch pipe 3b and the downstream side branch pipe 3c, the downstream side branch pipe 3c can be adjusted by adjusting the amount of water supply flowing through the upstream side branch pipe 3b. It is also possible to adjust the amount of water supplied to the water supply.
[0033]
　In the second embodiment, the temperature detection member is the temperature sensor 20, but the temperature sensor is not limited to the temperature sensor 20. If the inlet temperature, which is the temperature of the circulating water flowing into the economizer 2, can be estimated or calculated from the operating state of the integrated coal gasification combined cycle plant, the temperature of the estimation member or calculation member that performs such estimation or calculation It may be used as a detection member. Further, when the heat exchange amount of the economizer 2 can be estimated assuming the normal operating conditions of the integrated coal gasification combined cycle power plant, the temperature of the circulating water flowing out from the economizer 2 is detected to flow into the economizer 2. The inlet temperature, which is the temperature of circulating water, can be estimated. In such a case, even if the temperature sensor 20 is provided in the pipe 12, it can be said that the inlet temperature, which is the temperature of the circulating water flowing into the economizer 2, can be detected by correcting the detection value of the temperature sensor 20. The temperature sensor 20 may be provided in the pipe 12 on the downstream side in the flow direction of the circulating water with respect to the connection portion 11a between the upstream branch pipe 3b and the pipe 11.
Code description
[0034]
1 Exhaust cooler
2 Economizer
3 Water supply pipe
3a Main pipe
3b Upstream branch pipe
3c Downstream branch pipe
4 Steam drum
5 Exhaust heat boiler
6 Pump
11 Piping
11a Connection
12 Piping
12a Connection
20 Temperature sensor (temperature detection member)
30 Flow rate Control valve (inlet side supply amount adjustment member)
The scope of the claims
[Claim 1]
　And economizer and a flue gas and a first water heat exchanger,
　the first second water lower temperature than water and the water supply pipe for supplying the first water
with a,
　the second water from the economizer An exhaust gas cooler that is divided and supplied to the first water that flows out and the first water that flows into the economizer.
[Claim 2]
　The temperature detection member that detects the inlet temperature, which is the temperature of the first water
　flowing into the economizer, and the inlet side supply amount, which is the supply amount of the second water supplied to the first water flowing into the economizer. An inlet side supply amount adjusting member for adjusting
is provided, and the inlet side supply amount adjusting member adjusts the inlet side supply amount so that the inlet
　temperature is within a preset set temperature range. The exhaust gas cooler according to claim 1.
[Claim 3]
　A steam drum into which the first water flowing out of the economizer flows in is further provided, and a part of the second water is supplied to the first water flowing out of the economizer between the economizer and the steam drum. , The exhaust gas cooler according to claim 1 or 2.
[Claim 4]
　The exhaust heat boiler that heats the first water that has flowed into the steam drum to generate steam is further provided, and the
　exhaust gas is the first in the exhaust heat boiler before heat exchange with the first water in the economizer. 1 The exhaust gas cooler according to claim 3, which exchanges heat with water.
[Claim 5]
　The exhaust gas cooler according to any one of claims 1 to 4, wherein the exhaust gas is exhaust gas from a combustion furnace in an integrated coal gasification combined cycle plant.