阅读说明：本技术 废气冷却器 (Exhaust gas cooler ) 是由 吉田香织 村上盛纪 山崎步 菅利喜雄 国宗清隆 中山浩次 于 2019-02-22 设计创作，主要内容包括：废气冷却器具备：节能器,其将废气与第一水进行热交换；以及供水管,其用于向第一水供给温度比第一水的温度低的第二水,第二水分别向从节能器流出的第一水、以及流入节能器的第一水分割供给。(The exhaust gas cooler is provided with: an economizer that exchanges heat between the exhaust gas and the first water; and a water supply pipe for supplying second water having a temperature lower than that of the first water to the first water, the second water being dividedly supplied to the first water flowing out of the economizer and the first water flowing into the economizer, respectively.)

1. An exhaust gas cooler, wherein,

the exhaust gas cooler is provided with:

an economizer that exchanges heat between the exhaust gas and the first water; and

a water supply pipe for supplying second water having a temperature lower than that of the first water to the first water,

the second water is dividedly supplied to the first water flowing out of the economizer and the first water flowing into the economizer, respectively.

2. The exhaust gas cooler according to claim 1,

the exhaust gas cooler is provided with:

a temperature detection means that detects an inlet temperature, which is a temperature of the first water flowing into the economizer; and

an inlet-side supply amount adjusting member for adjusting an inlet-side supply amount, which is a supply amount of the second water supplied to the first water flowing into the economizer,

the exhaust gas cooler is configured to: the inlet-side supply amount adjusting member adjusts the inlet-side supply amount so that the inlet temperature falls within a preset temperature range.

3. The exhaust gas cooler according to claim 1 or 2,

the exhaust gas cooler further includes a steam drum into which the first water flowing out of the economizer flows, 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.

4. The exhaust gas cooler according to claim 3,

the exhaust gas cooler further includes a waste heat boiler that heats the first water flowing into the steam drum to generate steam,

the exhaust gas is heat-exchanged with the first water in the waste heat boiler before being heat-exchanged with the first water in the economizer.

5. The exhaust gas cooler according to any one of claims 1 to 4,

the exhaust gas is an exhaust gas from a combustion furnace in the integrated coal gasification combined cycle plant.

Technical Field

The present invention relates to an exhaust gas cooler for cooling exhaust gases.

Background

An economizer for exchanging heat between exhaust gas and water supply is provided in an exhaust gas cooler for cooling exhaust gas. When the dew point temperature of the exhaust gas is high, there is a concern that the temperature of the passing exhaust gas is lower than the dew point temperature due to heat exchange in the economizer so that dew condensation occurs. In the case of exhaust gas having corrosiveness, when the exhaust gas is condensed, corrosion of the economizer may be caused.

In the economizer described in patent document 1, the entire amount of the feed water to the steam-water drum flows into the economizer before flowing into the steam-water drum to exchange heat with the exhaust gas, but before the feed water flows into the economizer, warm water from the steam-water drum is mixed into the feed water to maintain the temperature of the feed water flowing into the economizer at a set temperature, thereby preventing condensation of the exhaust gas.

Disclosure of Invention

Problems to be solved by the invention

However, in the economizer described in patent document 1, since the entire amount of the supply water to the steam-water drum flows into the economizer, when the supply water amount increases, it is difficult to maintain the set temperature by mixing the warm water into the supply water, and condensation of the exhaust gas may occur.

In view of the above circumstances, an object of at least one embodiment of the present invention is to provide an exhaust gas cooler capable of suppressing condensation of exhaust gas in an economizer.

Means for solving the problems

An 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 second water having a temperature lower than that of the first water to the first water, the second water being dividedly supplied to the first water flowing out of the economizer and the first water flowing into the economizer, respectively.

According to this configuration, by supplying at least a part of the second water to the first water flowing into the economizer, the temperature of the first water flowing into the economizer becomes higher than that in the case where the entire amount of the second water is supplied to the first water flowing into the economizer. Therefore, the drop in the exhaust gas temperature caused by the heat exchange between the exhaust gas and the first water in the economizer is reduced, and therefore, the condensation of the exhaust gas can be suppressed in the economizer.

In some embodiments, the exhaust gas cooler may include: a temperature detection means that detects an inlet temperature, which is a temperature of the first water flowing into the economizer; and an inlet-side supply amount adjusting member for adjusting an inlet-side supply amount, which is a supply amount of the second water supplied to the first water flowing into the economizer, wherein the exhaust gas cooler is configured to: the inlet-side supply amount adjusting means adjusts the inlet-side supply amount so that the inlet temperature falls within a preset temperature range.

According to this configuration, by setting the appropriate set temperature range, the temperature of the exhaust gas can be maintained at the dew point temperature or higher in the economizer, and the risk of the first water boiling can be reduced.

In some embodiments, the exhaust gas cooler may further include a steam drum into which the first water flowing out of the economizer flows, and a part of the second water may be supplied to the first water flowing out of the economizer between the economizer and the steam drum. In this case, the exhaust gas cooler may further include a waste heat boiler that heats the first water flowing into the steam drum to generate steam, and the exhaust gas may be heat-exchanged with the first water in the waste heat boiler before being heat-exchanged with the first water in the economizer.

When the reduction in the exhaust gas temperature caused by the heat exchange between the exhaust gas and the first water in the economizer is reduced by supplying at least a part of the second water to the first water flowing into the economizer, the condensation of the exhaust gas in the economizer can be suppressed, but the cooling effect of the exhaust gas is deteriorated. However, according to this configuration, since the exhaust gas is cooled by generating steam in the waste heat boiler before flowing into the economizer, deterioration of the cooling effect of the exhaust gas can be suppressed by cooling in each of the waste heat boiler and the economizer.

In some embodiments, the exhaust gas may be an exhaust gas from a combustion furnace in the integrated coal gasification combined cycle plant. Sulfur trioxide (SO) is contained in exhaust gas from a combustion furnace in an integrated coal gasification combined cycle plant₃) Thus, the acid dew point is high. Therefore, the exhaust gas is likely to condense in the economizer. When containing SO₃The exhaust gas cooler of the integrated coal gasification combined cycle plant has an effect of suppressing condensation of the exhaust gas in the economizer, particularly, because the exhaust gas forms sulfuric acid when condensed.

Effects of the invention

According to at least one embodiment of the present invention, by supplying at least a part of the second water to the first water flowing into the economizer, the temperature of the first water flowing into the economizer becomes higher than that in the case where the entire amount of the second water is supplied to the first water flowing into the economizer. Therefore, the drop in the exhaust gas temperature caused by the heat exchange between the exhaust gas and the first water in the economizer is reduced, and therefore, the condensation of the exhaust gas can be suppressed in the economizer.

Drawings

Fig. 1 is a schematic configuration diagram of an exhaust gas cooler according to embodiment 1 of the present invention.

Fig. 2 is a schematic configuration diagram of an exhaust gas cooler according to embodiment 2 of the present invention.

Fig. 3 is a graph showing an example of the change with time of the temperature of the circulating water flowing into the economizer in the exhaust gas cooler according to embodiment 2 of the present invention.

Detailed Description

Hereinafter, several 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 constituent members described in the following embodiments are not intended to limit the scope of the present invention, and are merely illustrative examples.

(embodiment mode 1)

The exhaust gas cooler according to the present invention will be described by taking an example of an apparatus for cooling exhaust gas from a combustion furnace in an integrated coal gasification combined cycle plant. The exhaust gas cooler of the present invention is not limited to such a device, and may be used for a device for cooling an exhaust gas discharged from any device.

As shown in fig. 1, an exhaust gas cooler 1 according to embodiment 1 of the present invention includes: an economizer 2 that exchanges heat between the exhaust gas and circulating water (first water); and a water supply pipe 3 (second water supply pipe) for supplying water (second water) to the circulating water. The water supply pipe 3 includes one main pipe 3a, and two branch pipes, i.e., an upstream side branch pipe 3b and a downstream side branch pipe 3c, each having one end connected to the main pipe 3a so as to branch from the main pipe 3 a. The other end of the upstream branch pipe 3b is connected to a pipe 11 located upstream of the economizer 2 in the circulating water flow direction. The other end of the downstream branch pipe 3c is connected to a pipe 12 located downstream of the economizer 2 in the circulating water flow direction.

In the case where the exhaust gas cooler 1 is a device for cooling the exhaust gas from a combustion furnace in the integrated coal gasification combined cycle plant, the exhaust gas cooler 1 further includes: a steam drum 4 that communicates with the economizer 2 via a pipe 12; a waste heat boiler 5 that heats circulating water flowing into the steam drum 4 through a pipe 12 to generate steam; and a pump 6 for supplying the water in the steam drum 4 as circulating water to the economizer 2 through a pipe 11. The waste heat boiler 5 is configured to generate steam by heat exchange between the exhaust gas before flowing into the economizer 2 and the circulating water flowing into the steam drum 4.

Next, the operation of the exhaust gas cooler 1 according to embodiment 1 will be described.

The exhaust gas from the combustion furnace flows into the exhaust heat boiler 5, and in the exhaust heat boiler 5, the exhaust gas exchanges heat with water in the steam drum 4 to heat the water, thereby generating steam, and the steam flows out from the steam drum 4. On the other hand, water flows out of 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 of the waste heat boiler 5 flows into the economizer 2, and the exhaust gas and the circulating water heat-exchange 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.

Since the steam flows out from the steam drum 4, the same amount of supply water as the amount of the flowing steam needs to be supplied to the steam drum 4. The supply water is supplied to the circulating water circulating through the water supply pipe 3 so as to flow out of the steam drum 4 and return to the steam drum 4 again. Since the temperature of the feed water is usually lower than the temperature of the circulating water, if the entire amount of feed water is supplied to the circulating water flowing into the economizer 2, the temperature of the circulating water flowing into the economizer 2 is greatly reduced. SO is contained in exhaust gas from a combustion furnace in an integrated coal gasification combined cycle plant₃Therefore, the temperature of the circulating water flowing into the economizer 2 is low, and when the temperature of the exhaust gas is lower than the acid dew point due to heat exchange with the circulating water, the exhaust gas is condensed in the economizer 2. When containing SO₃Sulfuric acid is generated when the exhaust gas is condensed, and thus corrosion of the economizer 2 is caused.

On the other hand, when the entire amount of the feed water is supplied to the circulating water flowing out of the economizer 2, the circulating water flowing out of the steam drum 4 directly flows into the economizer 2. Depending on the operating conditions of the integrated coal gasification combined cycle plant, the temperature and flow rate of the exhaust gas from the combustion furnace and the temperature of the circulating water may vary. When the circulating water having a high temperature flows into the economizer 2, or the temperature of the exhaust gas flowing into the economizer 2 is high, or the flow rate of the exhaust gas flowing into the economizer 2 is large, the circulating water may be overheated and boil in the economizer 2. Since the economizer 2 is not designed on the premise that the circulating water is boiled in many cases, the economizer 2 may be damaged when the circulating water is boiled.

Therefore, in embodiment 1, after flowing through the main pipe 3 in the water supply pipe 3, the supply water is divided so as to flow through the upstream branch pipe 3b and the downstream branch pipe 3c, and flows into the pipes 11 and 12, respectively, to supply the circulation water flowing into the economizer 2 and the circulation water flowing out of the economizer 2, respectively. Here, if normal operating conditions of the integrated coal gasification combined cycle plant are assumed, it is possible to estimate a certain range 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 of the steam drum 4. By determining the flow rate of the feed water flowing through the upstream branch pipe 3b, that is, the amount of the feed water supplied to the circulating water flowing into the economizer 2, based on the ranges, the circulating water flowing into the economizer 2 can be adjusted to an appropriate temperature such that the exhaust gas does not condense and the circulating water does not boil in the economizer 2.

By supplying at least a part of the feed water to the circulating water flowing into the economizer 2 in this way, the temperature of the circulating water flowing into the economizer 2 becomes higher than in the case where the entire amount of the feed water is supplied to the circulating water flowing into the economizer 2. Therefore, the decrease in the exhaust gas temperature caused by the heat exchange between the exhaust gas and the circulating water in the economizer 2 is reduced, and therefore, the condensation of the exhaust gas can be suppressed in the economizer 2.

However, when the reduction in the exhaust gas temperature caused by the heat exchange between the exhaust gas and the circulating water in the economizer 2 is reduced by supplying at least a part of the supply water to the circulating water flowing into the economizer 2, the condensation of the exhaust gas in the economizer 2 can be suppressed, but the cooling effect of the exhaust gas is deteriorated. However, in embodiment 1, since the exhaust gas is cooled by generating steam in the waste heat boiler 5 before flowing into the economizer 2, deterioration of the cooling effect of the exhaust gas can be suppressed by cooling in each of the waste heat boiler 5 and the economizer 2.

(embodiment mode 2)

Next, an exhaust gas cooler according to embodiment 2 will be described. The exhaust gas cooler according to embodiment 2 is modified from embodiment 1 as follows: the amount of supply water to the circulating water is controlled so that the circulating water flowing into the economizer has a temperature in an appropriate range. In embodiment 2, the same components as those in embodiment 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in fig. 2, the pipe 11 is provided with a temperature sensor 20 (temperature detection means) for detecting an inlet temperature, which is the temperature of the circulating water flowing into the economizer 2, on a downstream side in the circulating water flow direction with respect to a connection portion 11a between the upstream branch pipe 3b and the pipe 11. The upstream branch pipe 3b is provided with a flow rate adjustment valve 30 (inlet-side supply amount adjustment means) for adjusting an inlet-side supply amount, which is a supply amount of the supply water to the circulating water flowing into the economizer 2, based on a detection value detected by the temperature sensor 20. The other structure is the same as embodiment 1.

Next, the operation of the exhaust gas cooler 1 according to embodiment 2 will be described.

In embodiment 2, at least a part of the feed water is supplied to the circulating water flowing into the economizer 2, whereby condensation of the exhaust gas in the economizer 2 can be suppressed, similarly to embodiment 1. The embodiment is different from embodiment 1 in that the supply amount of the feed water to be supplied to the circulating water flowing into the economizer 2 is adjusted based on the detection value detected by the temperature sensor 20. This difference from embodiment 1 will be described below.

The flow rate adjustment valve 30 adjusts the opening degree so that the detection value detected by the temperature sensor 20 falls within a preset temperature range, thereby adjusting the amount of the feed water flowing through the upstream branch pipe 3b, that is, the amount of the feed water supplied to the circulating water flowing into the economizer 2. The set temperature range has an upper limit value and a lower limit value. If the detected value detected by the temperature sensor 20 exceeds the upper limit value, the amount of supply water supplied to the circulating water flowing into the economizer 2 is increased by increasing the opening degree of the flow rate adjustment valve 30, and therefore the temperature of the circulating water flowing into the economizer 2 is decreased. On the other hand, if the detection value detected by the temperature sensor 20 is lower than the lower limit value, the amount of supply water supplied to the circulating water flowing into the economizer 2 is reduced by reducing the opening degree of the flow rate adjustment valve 30, and therefore the temperature of the circulating water flowing into the economizer 2 increases.

As shown in fig. 3, by such an operation, the temperature of the circulating water flowing into the economizer 2, which is the detection value detected by the temperature sensor 20, is maintained between the upper limit value and the lower limit value of the set temperature range.

Here, the upper limit value of the set temperature range is the highest 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 value of the set temperature range is the lowest temperature for preventing the exhaust gas from condensing due to heat exchange with the circulating water in the economizer 2. By appropriately setting the set temperature range in this manner, the temperature of the exhaust gas can be maintained at the dew point temperature or higher in the economizer 2, and the risk of boiling of the circulating water can be reduced.

In embodiment 2, the flow rate adjustment valve 30 is provided in the upstream branch pipe 3b, but may be provided in the downstream branch pipe 3 c. Since the supply water flowing through the main pipe 3a is divided by the upstream branch pipe 3b and the downstream branch pipe 3c, the amount of the supply water flowing through the downstream branch pipe 3c can be adjusted by adjusting the amount of the supply water flowing through the upstream branch pipe 3 b.

In embodiment 2, the temperature detection means is the temperature sensor 20, but is not limited to the temperature sensor. 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, etc., an estimation means or a calculation means for such estimation or calculation may be used as the temperature detection means. In addition, when the heat exchange amount of the economizer 2 can be estimated by assuming normal operating conditions of the integrated coal gasification combined cycle plant, the temperature of the circulating water flowing into the economizer 2, that is, the inlet temperature can be estimated by detecting the temperature of the circulating water flowing out of the economizer 2. In such a case, it can be said that even if the temperature sensor 20 is provided in the pipe 12, the temperature of the circulating water flowing into the economizer 2, that is, the inlet temperature can be detected by correcting the detection value of the temperature sensor 20, and therefore the temperature sensor 20 may be provided on the downstream side in the circulating water flow direction of the pipe 12 with respect to the connection portion 11a between the upstream branch pipe 3b and the pipe 11.

Description of reference numerals:

1 exhaust gas cooler

2 energy saver

3 water supply pipe

3a main pipe

3b upstream side branch pipe

3c downstream branch pipe

4 steam boiler barrel

5 waste heat boiler

6 Pump

11 piping

11a connecting part

12 piping

12a connection part

20 temperature sensor (temperature detecting component)

30 flow rate regulating valve (inlet side supply amount regulating member).