JP2000257806A - Drain recovery system for heat exchanger - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To normalize a deaerator by making it possible to adjust the amount of drain flowing into a deaerator from an exhaust gas reheater, prevent loss of boiler water, and improve thermal efficiency. Provide a good heat exchanger drain recovery system. SOLUTION: Steam generated from a boiler 11 is supplied to an exhaust gas reheater 13 via a distribution pipe 12, and exhaust steam from the exhaust gas reheater 13 is introduced into a deaerator 15 via a steam trap 14. In the drain recovery system 10 of a heat exchanger capable of supplying water from the condensate tank 16 to the boiler 11 and further to the deaerator 15, the water is returned to the downstream side of the steam trap 14 via an automatic on-off valve 17. A branch pipe 18 connected to the water tank 16 is provided, and the automatic on-off valve 17 is opened and closed according to the pressure of the deaerator 15 to maintain the pressure of the deaerator 15 within a certain range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drain recovery system for a heat exchanger which can control the pressure of a deaerator.

[0002]

2. Description of the Related Art As shown in FIG.
The exhaust gas generated from 1 is 900 ° C. in the combustion chamber 52.
After being completely burned at about the same temperature, it is cooled by the boiler 53, further cooled by the exhaust gas temperature controller 54, and then discharged from the chimney 56 through the bag filter 55. However, the exhaust gas cooled in this way becomes white smoke when discharged from the chimney 56 if the temperature is too low. Also,
Recently, the exhaust gas is sometimes treated in the catalytic reaction column 57 before being discharged from the chimney 56 due to a problem such as dioxin.
It is about 00 ° C. Therefore, it is desirable to reheat the exhaust gas passing through the bag filter 55 to about 200 ° C. This heat treatment is performed using the steam generated from the boiler 53.

The drain generated at this time is recovered by a drain recovery system 58 of the heat exchanger shown in FIG. This will be described below. The steam generated from the boiler 53 is distributed in a distribution pipe 59, and a predetermined amount is sent to an exhaust gas reheater 60 for reheating the exhaust gas, a necessary amount of the remaining steam is sent to a deaerator 61 to be described later, and The water is sent to and utilized by a heat utilization facility 62 such as a steam turbine.
Here, the predetermined amount sent to the exhaust gas reheater 60 refers to an amount necessary to heat the exhaust gas to about 200 ° C.
The steam that has passed through the exhaust gas reheater 60 becomes pressurized saturated water (hereinafter referred to as drain A) at about 250 ° C., is once trapped by the steam trap 63, and is continuously supplied to the deaerator 61. Sent. On the other hand, the steam used in the heat utilization facility 62 becomes water at about 80 ° C. (hereinafter, referred to as drain B), is stored in the condensate water tank 64, and is released while the inflow amount is adjusted by the level control valve 65. It is sent to the porcelain 61.

In the deaerator 61, the pressure and the level (drain amount) of the deaerator 61 are detected by a pressure detector 66 and a level detector 67, and the deaerator 61 is 2.7 kg /
cm ² (about 140 ° C.). That is, this adjustment during normal operation is performed by mixing the drain A and the drain B, and by flowing an appropriate amount of superheated steam from the distribution pipe 59 via the pressure control valve 68. And the drain (water) degassed by this deaerator 61
Are collected again in the boiler 53. Note that reference numeral 6
Reference numeral 9 denotes a boiler feed pump, and reference numeral 70 denotes a deaerator feed pump.

[0005]

However, in the above-mentioned conventional drain recovery system 58 for the heat exchanger, the deaerator 61 unconditionally receives the drain from the exhaust gas reheater 60. There was a case where a problem occurred in the pressure control of. That is, in a normal state, the amount of drain sent from the exhaust gas reheater 60 to the deaerator 61 is smaller than the required steam of the deaerator 61, so there is no problem (in this case, steam is directly sent from the distribution pipe 59). ), When the boiler is under low load, and when there is no wind, etc., the exhaust gas reheater 6
Since the amount of drain sent to the deaerator 61 from 0 becomes larger than the required steam, the pressure control of the deaerator 61 becomes impossible and the pressure of the deaerator 61 increases.

In such a case, the pressure in the deaerator 61 is reduced by operating a relief valve 71 provided in the boiler feed pump 69 or a safety valve 72 provided in the deaerator 61. However, this requires the trouble of losing boiler water and replenishing the water to the drain recovery system 58, and is undesirable in terms of thermal efficiency. The present invention has been made in view of such circumstances, and aims at normalization of the deaerator by enabling the amount of drain flowing from the exhaust gas reheater to the deaerator to prevent loss of boiler water. It is another object of the present invention to provide a drain recovery system for a heat exchanger that is highly efficient.

[0007]

According to a first aspect of the present invention, there is provided a drain recovery system for a heat exchanger, which supplies steam generated from a boiler to an exhaust gas reheater via a distribution pipe. In a drain recovery system of a heat exchanger capable of supplying water from a condensate tank to exhaust gas from a heater through a steam trap into a deaerator via a steam trap and supplying the boiler, On the downstream side of the steam trap, a branch pipe connected to the condensate tank via an automatic opening / closing valve is provided, and the automatic opening / closing valve is opened / closed according to the pressure of the deaerator. The pressure is kept within a certain range. In the drain recovery system for the heat exchanger according to the present invention, the drain generated in the exhaust gas reheater is collected in two systems including a deaerator alone and a condensate tank. Therefore, if a problem occurs in the pressure control of the deaerator (when the pressure of the deaerator is out of the control range and shows a (high) abnormal value), the automatic opening / closing valve of the branch pipe connected to the condensate tank. By sending a control signal to open and close this automatic on-off valve, the total amount of drain generated in the exhaust gas reheater,
Alternatively, a part can be released to the condensate tank.

Further, a drain recovery system for a heat exchanger according to a second aspect of the present invention supplies steam generated from a boiler to an exhaust gas reheater via a distribution pipe, and receives the steam from the exhaust gas reheater. In a drain recovery system of a heat exchanger capable of supplying exhaust steam into a deaerator through a steam trap and supplying the boiler with the boiler, and further supplying the deaerator with water from a condensate tank, A steam regulating valve is provided between the exhaust gas reheater and the exhaust gas reheater, and the opening of the steam regulating valve is adjusted in accordance with the pressure of the deaerator to maintain the pressure of the deaerator in a certain range. In the drain recovery system of the heat exchanger according to the present invention, since a steam regulating valve is provided between the distribution pipe and the exhaust gas reheater, a problem occurs in the pressure control of the deaerator (the deaerator). Pressure is out of control range,
(If an abnormal value is indicated), adjust the opening of the steam control valve according to the pressure of the deaerator to remove all or part of the drain flowing into the deaerator from the exhaust gas reheater. Can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is an explanatory diagram of a drain recovery system of the heat exchanger according to the first embodiment of the present invention,
FIG. 2 is an explanatory diagram of a drain recovery system for a heat exchanger according to a second embodiment of the present invention.

As shown in FIG. 1, a drain recovery system 10 for a heat exchanger according to a first embodiment of the present invention transfers steam generated from a boiler 11 to an exhaust gas reheater 13 through a distribution pipe 12. The steam supplied from the exhaust gas reheater 13 is supplied to the deaerator 1 via the steam trap 14.
5 and supply it to the boiler 11 again,
Further, water from the condensate tank 16 can be supplied to the deaerator 15. Further, the drain recovery system 10 of the heat exchanger is characterized in that a branch pipe 18 connected to the condensate tank 16 via an automatic opening / closing valve 17 is provided downstream of the steam trap 14. The drain recovery system 10 of the heat exchanger according to the present embodiment
Applies to facilities similar to those shown in FIG.

The operation of the drain recovery system 10 for a heat exchanger during normal operation will be described below. The operation of the drain recovery system 58 for a heat exchanger according to the conventional example during normal operation will be briefly described. I do. The steam generated from the boiler 11 passes through a distribution pipe 12 to an exhaust gas reheater 13.
Supplied to Exhaust steam (drain) that has passed through the exhaust gas reheater 13 is once trapped by the steam trap 14 and continuously sent to the deaerator 15 by a fixed amount. On the other hand, the steam from the boiler 11 used in the heat utilization facility 19 is:
It is stored in a condensate tank 16, and the inflow amount is controlled by a level control valve 20 and sent to the deaerator 15. In addition, deaerator 15
In, the pressure and the level (drain amount) of the deaerator 15 are detected by the pressure detector 21 and the level detector 22, and the deaerator 15 is adjusted to a predetermined pressure and a predetermined temperature. This adjustment at the time of normal operation is performed because the deaerator 15 does not reach the predetermined pressure and temperature only by mixing the drain flowing from the exhaust gas reheater 13 and the condensate tank 16 into the deaerator 15. This is performed by flowing an appropriate amount of superheated steam from 12 through a pressure control valve 23. During normal operation, the automatic on-off valve 17 is kept closed.

The operation of the drain recovery system 10 of the heat exchanger when the boiler is operated at a low load, when the boiler is not operating, and the like during normal operation of the boiler will be described below. In this case, the amount of steam generated from the boiler 11 is smaller than the amount of exhaust gas, and the amount of drain that can flow into the boiler 11 from the deaerator 15 is reduced. Therefore, the amount of drain that can flow into the deaerator 15 is inevitably reduced. If the amount of high-calorie drain flowing from the exhaust gas reheater 13 is constant with respect to the amount of exhaust gas, the amount of drainage from the condensate tank 16 is reduced. Breath 15
Since the amount of low-calorie (low-temperature) drain sent to the deaerator 15 is small, the pressure in the deaerator 15 increases.

In the present invention, in such a case, the drain that has passed through the exhaust gas reheater 13 is caused to flow to the branch pipe 18 connected to the condensate tank 16 via the automatic opening / closing valve 17. The automatic opening / closing valve 17 is opened and closed according to the pressure of the deaerator 15 (opens when the pressure of the deaerator 15 is high, and closes when the pressure of the deaerator 15 is low). It is kept within a certain range (for example, about 2.5 to 3.5 kg / cm ² ). Thereby, the amount of the high-calorie drain sent to the deaerator 15 is reduced, and an abnormal increase in the pressure of the deaerator 15 can be suppressed. In addition, in case of emergency (such as when the automatic on-off valve does not operate), the safety valve 24
And a relief valve 25 is provided. Reference numeral 26 denotes a boiler water supply pump, reference numeral 27 denotes a deaerator water supply pump, and reference numeral 28 denotes a check valve.

Next, a drain recovery system 29 for a heat exchanger according to a second embodiment will be described with reference to FIG. Note that the same components as those described in the first embodiment are denoted by the same reference numerals and description thereof is omitted. The drain recovery system 29 of the heat exchanger
A steam control valve 30 is provided between the exhaust gas reheater 13 and the opening of the steam control valve 30 is adjusted in accordance with the pressure of the deaerator 15 so that the pressure of the deaerator 15 is maintained within a certain range. It is characterized by. The opening of the steam regulating valve 30 is adjusted by the pressure detected by the pressure detector 21 provided in the deaerator 15. For example, when the pressure of the steam regulating valve 30 exceeds a certain fixed pressure, the steam regulating valve 30 increases in proportion to the pressure rise. Lower the valve opening (close the valve)
To do. This makes it possible to adjust the amount of high-calorie drain sent to the deaerator 15 while minimizing the decrease in steam sent to the exhaust gas reheater 13,
An abnormal increase in the pressure of the deaerator 15 can be suppressed.

As described above, the present invention has been described with reference to some embodiments. However, the present invention is not limited to the configurations described in the above embodiments, and is described in the claims. It includes other embodiments and modifications that can be considered within the scope of the matters described. For example, in the first embodiment, a heat utilization facility such as a turbine may be connected to the branch pipe 18 connected to the condensate tank 16 and then flow to the condensate tank 16. Can be used more effectively.

[0016]

According to the first aspect of the present invention, in the drain recovery system for a heat exchanger, a branch pipe connected to a condensate tank via an automatic on-off valve is provided downstream of the steam trap.
Since the automatic on-off valve opens and closes according to the pressure of the deaerator, all or part of the drain is released to the condensate tank, and the amount of drain flowing from the exhaust gas reheater to the deaerator can be adjusted to degas. This makes it possible to normalize the vessel, prevent the safety valve or relief valve from operating, and operate the exhaust gas reheater stably, avoid boiler water loss, and effectively use heat energy. Further, in the drain recovery system for a heat exchanger according to the second aspect, a steam regulating valve is provided between the distribution pipe and the exhaust gas reheater, and the opening of the steam regulating valve is adjusted according to the pressure of the deaerator. Therefore, the amount of drain flowing into the deaerator or a part of it is reduced to normalize the deaerator, prevent the safety valve or relief valve from operating, avoid boiler water loss, and effectively use heat energy. Can be used.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a drain recovery system for a heat exchanger according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a drain recovery system for a heat exchanger according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a facility provided with a drain recovery system for a heat exchanger according to a conventional example.

FIG. 4 is an explanatory view of a drain recovery system for a heat exchanger according to a conventional example.

[Explanation of symbols]

10: drain recovery system of heat exchanger, 11: boiler, 12: distribution pipe, 13: exhaust gas reheater, 14: steam trap, 15: deaerator, 16: condensate tank, 1
7: Automatic on-off valve, 18: Branch pipe, 19: Heat utilization equipment, 2
0: level control valve, 21: pressure detector, 22: level detector, 23: pressure control valve, 24: safety valve, 25: relief valve, 26: boiler feed pump, 27: deaerator feed pump, 28: reverse Stop valve, 29: Drain recovery system for heat exchanger, 30: Steam flow regulating valve

Claims (2)

[Claims] 1. Steam generated from a boiler is supplied to an exhaust gas reheater via a distribution pipe, and steam discharged from the exhaust gas reheater is supplied to a deaerator via a steam trap and supplied to the boiler. Further, in the drain recovery system of the heat exchanger capable of supplying water from the condensate tank to the deaerator, the degasser is connected to the condensate tank via an automatic on-off valve on the downstream side of the steam trap. A drain recovery system for a heat exchanger, wherein a branch pipe is provided, the automatic opening / closing valve is opened / closed according to the pressure of the deaerator, and the pressure of the deaerator is maintained within a certain range. 2. The steam generated from the boiler is supplied to an exhaust gas reheater via a distribution pipe, and the exhaust steam from the exhaust gas reheater is supplied to a deaerator via a steam trap and supplied to the boiler. Further, in the drain recovery system of a heat exchanger capable of supplying water from a condensate tank to the deaerator, a steam regulating valve is provided between the distribution pipe and the exhaust gas reheater; A drain recovery system for a heat exchanger, wherein the degree of opening is adjusted according to the pressure of the deaerator, and the pressure of the deaerator is maintained within a certain range.