A low-temperature economizer rapid water discharge and online leak detection isolation system and method

Abstract

The present invention discloses a system and method for rapid water discharge and online leakage detection and isolation of a low-temperature economizer. An inlet main pipe valve is arranged on the inlet pipeline of the low-temperature economizer, a heat exchanger module inlet pipeline branch valve is arranged at the inlet of each heat exchanger module, an outlet main pipe valve is arranged on the outlet pipeline of the low-temperature economizer, and a heat exchanger module outlet pipeline branch valve is arranged at the outlet of each heat exchanger module; the low-temperature economizer sewage discharge system pipeline is connected with the low-temperature economizer inlet and outlet large headers and the headers of the heat exchanger modules; the low-temperature economizer exhaust system pipeline is connected with the highest point of the low-temperature economizer outlet pipeline; the outlet of the compressed air storage tank is connected with the outlet of each heat exchanger module via the compressed air purge system pipeline, and a pressure transmitter is arranged at the outlet of each heat exchanger module. The system and method can realize rapid water discharge and online leakage detection and isolation of the low-temperature economizer, and improve the stability and economy of the system operation.

Description

Technical Field

[0001] The invention belongs to the technical field of power station boiler flue gas waste heat recovery, and relates to a low-temperature economizer rapid water discharge and online leak detection isolation system and method. Background Art

[0002] In the actual operation of the boiler, the exhaust gas temperature at the air preheater outlet is mostly higher than the design value requirements due to factors such as dust accumulation on the heating surface, changes in the type of coal used, and insufficient operating level. In order to solve the problems of reduced boiler efficiency, low efficiency of the electrostatic precipitator, and high water consumption of the wet desulfurization system caused by the high exhaust gas temperature at the air preheater outlet, the flue gas waste heat recovery technology is generally used to reduce the exhaust gas temperature. Among the ways to utilize the waste heat of the flue gas of power station boilers, the most widely used method is to install a heat exchanger at the tail flue of the boiler, that is, the low-temperature economizer system.

[0003] In recent years, against the backdrop of comprehensive ultra-low emission and energy-saving transformation of coal-fired power plants, low-temperature economizer systems have developed rapidly. Since most low-temperature economizer systems are centralized transformations, there are problems such as imperfect design and insufficient initial operating experience. Low-temperature economizers are prone to heat exchange tube leakage during operation. After a low-temperature economizer heat exchange tube leaks, it is generally difficult to determine the specific location of the leaking module during operation. Most of them take the approach of shutting down all modules of the low-temperature economizer and pressurizing each module for leak detection after the unit is shut down. As a result, low-temperature economizer modules without leaks cannot be put into operation for a long time, affecting the unit's coal consumption and electrostatic precipitator efficiency. When the ambient temperature in northern regions is low, the method of pressurizing each module for leak detection after shutdown is prone to freezing and cracking of the heat exchange tubes and secondary leakage.

[0004] When the ambient temperature in the northern region is low, the low-temperature economizer system is prone to water accumulation and failure to drain completely or untimely when it is shut down, causing the heat exchange tubes to freeze and crack, making it impossible for the low-temperature economizer system to be put into operation in time, threatening the safe operation of tail equipment such as electrostatic precipitators and induced draft fans.

[0005] The above-mentioned problems existing in the operation of the low-temperature economizer seriously restrict the large-scale application of the low-temperature economizer system, especially in the cold northern regions. Therefore, there is an urgent need for a system and method that can realize rapid water discharge and online leak detection and isolation of the low-temperature economizer. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a system and method for rapid water discharge and online leak detection and isolation of a low-temperature economizer. The system and method can achieve rapid water discharge and online leak detection and isolation of a low-temperature economizer, thereby improving the stability and economy of the system operation.

[0007] To achieve the above-mentioned purpose, the low-temperature economizer rapid water discharge and online leak detection isolation system of the present invention comprises a low-temperature economizer sewage discharge system pipeline, a low-temperature economizer exhaust system pipeline, a compressed air storage tank and a compressed air purge system pipeline;

[0008] The low-temperature economizer includes a low-temperature economizer inlet pipeline, a low-temperature economizer outlet pipeline and a plurality of heat exchanger modules, wherein the inlet of each heat exchanger module is connected with the low-temperature economizer inlet pipeline, the outlet of each heat exchanger module is connected with the low-temperature economizer outlet pipeline, an inlet main pipe valve is arranged on the low-temperature economizer inlet pipeline, a heat exchanger module inlet pipeline branch valve is arranged at the inlet of each heat exchanger module, an outlet main pipe valve is arranged on the low-temperature economizer outlet pipeline, and a heat exchanger module outlet pipeline branch valve is arranged at the outlet of each heat exchanger module;

[0009] The low-temperature economizer sewage discharge system pipeline is connected to the low-temperature economizer inlet and outlet large headers and the headers of the heat exchanger modules; the low-temperature economizer exhaust system pipeline is connected to the highest point of the low-temperature economizer outlet pipeline; the outlet of the compressed air storage tank is connected to the outlet of each heat exchanger module through the compressed air purge system pipeline, and a pressure transmitter is provided at the outlet of each heat exchanger module.

[0010] It also includes a low-temperature economizer sewage and exhaust pipeline collecting main pipe, wherein the low-temperature economizer sewage system pipelines and the low-temperature economizer exhaust system pipelines are connected to the low-temperature economizer sewage and exhaust pipeline collecting main pipe.

[0011] The sewage system main pipe valve, outlet main pipe valve, heat exchanger module outlet pipeline branch valve, inlet main pipe valve and heat exchanger module inlet pipeline branch valve are all electric valves;

[0012] The low-temperature economizer inlet and outlet large header drain valves and the heat exchanger module header drain valves are all manual valves.

[0013] The low-temperature economizer inlet pipeline, the low-temperature economizer outlet pipeline and the lowest point of the water inlet header of the heat exchanger module are all connected to the low-temperature economizer sewage system pipeline, and the low-temperature economizer sewage system pipeline is connected to the low-temperature economizer sewage and exhaust pipeline collecting mother pipe.

[0014] An exhaust valve is provided on the exhaust system pipeline of the low-temperature economizer.

[0015] A compressed air main pipe valve is arranged on the compressed air purge system pipeline, and a compressed air branch pipe valve is arranged between the compressed air purge system pipeline and the outlet of each heat exchanger module.

[0016] The main valve of the compressed air main pipe and the branch valves of the compressed air branch pipe are all electric valves.

[0017] The low-temperature economizer inlet and outlet large header drain valves and the heat exchanger module header drain valves are normally open valves, and the main valve of the sewage system mother pipe is closed when the low-temperature economizer is running.

[0018] A method for rapid water discharge and online leak detection and isolation of a low-temperature economizer comprises the following steps:

[0019] When the low-temperature economizer system is operating normally, close the main valve of the sewage system main pipe, open the exhaust valve of the exhaust system pipeline, and exhaust all heat exchanger modules in a unified manner. After the low-temperature economizer is filled with water, close the exhaust valve of the exhaust system pipeline, open the sewage valve of the inlet and outlet large headers of the low-temperature economizer and the sewage valve of the heat exchanger module header. When the low-temperature economizer is shut down, close the main valve of the inlet main pipe and the main valve of the outlet main pipe, and open the main valve of the sewage system main pipe to drain water;

[0020] After the water is drained, keep the branch valve of the heat exchanger module inlet pipeline open, close the branch valve of the heat exchanger module outlet pipeline, open the main valve of the compressed air main pipe, and then open the branch valves of each compressed air branch pipe in turn to inflate and drain the heat exchanger module to ensure that the water of each heat exchanger module is drained;

[0021] Close the inlet and outlet main valves, wait, and if the pressure drop detected by the pressure transmitter is greater than or equal to the preset range, it means that the low-temperature economizer is leaking as a whole;

[0022] When the low-temperature economizer leaks as a whole, open the inlet main pipe valve to restore the water side pressure of all heat exchanger modules to normal, close all the inlet pipeline branch valves and outlet pipeline branch valves of the heat exchanger modules, and when the pressure detected by any pressure transmitter drops, it means that the heat exchanger module corresponding to the pressure transmitter is leaking.

[0023] The present invention has the following beneficial effects:

[0024] The low-temperature economizer rapid water discharge and online leak detection isolation system and method described in the present invention are specifically operated. When the low-temperature economizer system is operating normally, the main valve of the sewage system mother pipe and the exhaust valve of the exhaust system pipeline are closed, and the low-temperature economizer inlet and outlet large manifold sewage valves and the heat exchanger module manifold sewage valves are opened. When the low-temperature economizer is shut down, the inlet mother pipe main valve and the outlet mother pipe main valve are closed, and the sewage system mother pipe main valve is opened. More than 90% of the working fluid in the low-temperature economizer can be discharged within 15 minutes, thereby preventing the low-temperature economizer from freezing due to long-term water storage. After the water discharge is completed, the heat exchanger module is inflated and drained by compressed gas to ensure that each heat exchanger module is drained cleanly. In addition, when the low-temperature economizer system is in operation, it can open or close the low-temperature economizer inlet and outlet main valves and the inlet and outlet branch valves of each heat exchanger module to realize online leak detection and isolation of leaking heat exchanger modules. The system is simple, with less operation, operation and maintenance workload. It can alleviate the freezing and cracking of low-temperature economizer heat exchanger tubes in cold northern regions, realize online leak detection and isolation of leaking modules, greatly improve the anti-freeze ability of the low-temperature economizer, and improve the stability and economy of the system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention.

[0026] Among them, 1 is the heat exchanger module, 2 is the low-temperature economizer inlet pipeline, 201 is the inlet mother pipe main valve, 202 is the heat exchanger module inlet pipeline branch valve, 3 is the low-temperature economizer outlet pipeline, 301 is the outlet mother pipe main valve, 302 is the heat exchanger module outlet pipeline branch valve, 4 is the low-temperature economizer sewage system pipeline, 401 is the sewage system mother pipe main valve, 402 is the low-temperature economizer inlet and outlet large header sewage valve, 403 is the heat exchanger module header sewage valve, 5 is the low-temperature economizer exhaust system pipeline, 501 is the exhaust system pipeline exhaust valve, 6 is the compressed air purge system pipeline, 601 is the compressed air mother pipe main valve, 602 is the compressed air branch pipe branch valve, 7 is the compressed air storage tank, 8 is the low-temperature economizer sewage, the exhaust pipeline is collected by the mother pipe, and 9 is the pressure transmitter. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0028] refer to Figure 1The low-temperature economizer rapid water discharge and online leak detection isolation system of the present invention comprises a low-temperature economizer sewage discharge system pipeline 4, a low-temperature economizer exhaust system pipeline 5, a compressed air storage tank 7 and a compressed air purge system pipeline 6; the low-temperature economizer comprises a low-temperature economizer inlet pipeline 2, a low-temperature economizer outlet pipeline 3 and a plurality of heat exchanger modules 1, wherein the inlet of each heat exchanger module 1 is connected with the low-temperature economizer inlet pipeline 2, the outlet of each heat exchanger module 1 is connected with the low-temperature economizer outlet pipeline 3, the low-temperature economizer inlet pipeline 2 is provided with an inlet main pipe valve 201, and the inlet of each heat exchanger module 1 is connected with the low-temperature economizer outlet pipeline 3. A heat exchanger module inlet pipeline branch valve 202 is provided, an outlet main pipe valve 301 is provided on the low-temperature economizer outlet pipeline 3, and a heat exchanger module outlet pipeline branch valve 302 is provided at the outlet of each heat exchanger module 1; the low-temperature economizer sewage discharge system pipeline 4 is connected to the low-temperature economizer inlet and outlet large headers and the headers of the heat exchanger module 1; the low-temperature economizer exhaust system pipeline 5 is connected to the highest point of the low-temperature economizer outlet pipeline 3; the outlet of the compressed air storage tank 7 is connected to the outlet of each heat exchanger module 1 through the compressed air purge system pipeline 6, and a pressure transmitter 9 is provided at the outlet of each heat exchanger module 1.

[0029] The present invention also includes a low-temperature economizer sewage and exhaust pipeline collecting mother pipe 8, wherein the low-temperature economizer sewage system pipeline 4 and the low-temperature economizer exhaust system pipeline 5 are connected to the low-temperature economizer sewage and exhaust pipeline collecting mother pipe 8.

[0030] The sewage system main pipe valve 401, outlet main pipe valve 301, heat exchanger module outlet pipeline branch valve 302, inlet main pipe valve 201 and heat exchanger module inlet pipeline branch valve 202 are all electric valves; the low-temperature economizer inlet and outlet large header sewage valve 402 and the heat exchanger module header sewage valve 403 are all manual valves.

[0031] The low-temperature economizer inlet pipeline 2, the low-temperature economizer outlet pipeline 3 and the lowest point of the water inlet header of the heat exchanger module 1 are all connected to the low-temperature economizer sewage system pipeline 4, and the low-temperature economizer sewage system pipeline 4 is connected to the low-temperature economizer sewage and exhaust pipeline collecting mother pipe 8.

[0032] An exhaust valve 501 is provided on the low-temperature economizer exhaust system pipeline 5 .

[0033] A compressed air main pipe valve 601 is provided on the compressed air purge system pipeline 6, and a compressed air branch pipe valve 602 is provided between the compressed air purge system pipeline 6 and the outlet of each heat exchanger module 1. The compressed air main pipe valve 601 and the compressed air branch pipe valve 602 are both electric valves.

[0034] The low-temperature economizer inlet and outlet large header drain valve 402 and the heat exchanger module header drain valve 403 are both normally open valves, and the main valve 401 of the sewage system main pipe is closed when the low-temperature economizer is running.

[0035] The low-temperature economizer rapid water discharge and online leak detection and isolation method of the present invention comprises the following steps:

[0036] When the low-temperature economizer system is operating normally, close the main valve 401 of the sewage system main pipe, open the exhaust valve 501 of the exhaust system pipeline, and exhaust the heat exchanger modules 1 uniformly. After the low-temperature economizer is filled with water, close the exhaust valve 501 of the exhaust system pipeline, open the low-temperature economizer inlet and outlet large header sewage valve 402 and the heat exchanger module header sewage valve 403. When the low-temperature economizer is shut down, close the inlet main pipe main valve 201 and the outlet main pipe main valve 301, and open the sewage system main pipe main valve 401 to drain water;

[0037] After the water is drained, keep the heat exchanger module inlet pipeline branch valve 202 open, close the heat exchanger module outlet pipeline branch valve 302, open the compressed air main pipe main valve 601, and then open the compressed air branch pipe branch valves 602 in sequence to inflate and drain the heat exchanger module 1 to ensure that the water is drained from each heat exchanger module 1;

[0038] A pressure transmitter 9 is provided at the outlet header pipe of each heat exchanger module 1. The working fluid in the low-temperature economizer is an incompressible fluid. When a leak occurs, the pressure detected by the pressure transmitter 9 is significantly reduced. Therefore, by isolating the heat exchanger module 1 and observing the pressure change of the working fluid in the heat exchanger module 1, it is possible to determine whether the low-temperature economizer has a leak.

[0039] Close the inlet main pipe valve 201 and the outlet main pipe valve 301. After 10 minutes, if the pressure drop detected by the pressure transmitter 9 is greater than or equal to the preset range, it means that the low-temperature economizer is leaking as a whole.

[0040] When the low-temperature economizer leaks as a whole, open the inlet main pipe valve 201 to restore the water side pressure of all heat exchanger modules 1 to normal, close all heat exchanger module inlet pipeline branch valves 202 and heat exchanger module outlet pipeline branch valves 302, and when the pressure detected by any pressure transmitter 9 drops, it means that the heat exchanger module 1 corresponding to the pressure transmitter 9 is leaking.

Claims

1. A low-temperature economizer rapid water discharge and online leak detection isolation system, characterized in that: It includes a low-temperature economizer sewage discharge system pipeline (4), a low-temperature economizer exhaust system pipeline (5), a compressed air storage tank (7) and a compressed air purge system pipeline (6); The low-temperature economizer comprises a low-temperature economizer inlet pipeline (2), a low-temperature economizer outlet pipeline (3) and a plurality of heat exchanger modules (1), wherein the inlet of each heat exchanger module (1) is connected to the low-temperature economizer inlet pipeline (2), the outlet of each heat exchanger module (1) is connected to the low-temperature economizer outlet pipeline (3), an inlet main pipe valve (201) is arranged on the low-temperature economizer inlet pipeline (2), a heat exchanger module inlet pipeline branch valve (202) is arranged at the inlet of each heat exchanger module (1), an outlet main pipe valve (301) is arranged on the low-temperature economizer outlet pipeline (3), and a heat exchanger module outlet pipeline branch valve (302) is arranged at the outlet of each heat exchanger module (1); The low-temperature economizer sewage discharge system pipeline (4) is connected to the low-temperature economizer inlet and outlet large headers and the headers of the heat exchanger modules (1); the low-temperature economizer exhaust system pipeline (5) is connected to the highest point of the low-temperature economizer outlet pipeline (3); the outlet of the compressed air storage tank (7) is connected to the outlet of each heat exchanger module (1) through the compressed air purge system pipeline (6), and a pressure transmitter (9) is provided at the outlet of each heat exchanger module (1); It also includes a low-temperature economizer sewage and exhaust pipeline collecting main pipe (8), wherein the low-temperature economizer sewage system pipeline (4) and the low-temperature economizer exhaust system pipeline (5) are connected to the low-temperature economizer sewage and exhaust pipeline collecting main pipe (8); An exhaust system pipeline exhaust valve (501) is provided on the low-temperature economizer exhaust system pipeline (5); A compressed air main pipe valve (601) is provided on the compressed air purge system pipeline (6), and a compressed air branch pipe valve (602) is provided between the compressed air purge system pipeline (6) and the outlet of each heat exchanger module (1).

2. The low-temperature economizer rapid water discharge and online leak detection isolation system according to claim 1 is characterized in that: The sewage system main pipe valve (401), the outlet main pipe valve (301), the heat exchanger module outlet pipeline branch valve (302), the inlet main pipe valve (201) and the heat exchanger module inlet pipeline branch valve (202) are all electric valves; The low-temperature economizer inlet and outlet large header drain valve (402) and the heat exchanger module header drain valve (403) are both manual valves.

3. The low-temperature economizer rapid water discharge and online leak detection isolation system according to claim 1 is characterized in that: The low-temperature economizer inlet pipeline (2), the low-temperature economizer outlet pipeline (3) and the lowest point of the water inlet header of the heat exchanger module (1) are all connected to the low-temperature economizer sewage system pipeline (4), and the low-temperature economizer sewage system pipeline (4) is connected to the low-temperature economizer sewage and exhaust pipeline collecting mother pipe (8).

4. The low-temperature economizer rapid water discharge and online leak detection isolation system according to claim 1 is characterized in that: The compressed air main pipe main valve (601) and the compressed air branch pipe branch valve (602) are both electric valves.

5. The low-temperature economizer rapid water discharge and online leak detection isolation system according to claim 1 is characterized in that: The low-temperature economizer inlet and outlet large header drain valve (402) and the heat exchanger module header drain valve (403) are both normally open valves, and the main valve (401) of the drain system main pipe is closed when the low-temperature economizer is in operation.

6. A method for rapid water discharge and online leak detection and isolation of a low-temperature economizer, characterized in that: The low-temperature economizer rapid water discharge and online leak detection isolation system according to claim 1 comprises the following steps: When the low-temperature economizer system is operating normally, the main valve (401) of the sewage system main pipe is closed, the exhaust valve (501) of the exhaust system pipeline is opened, and the exhaust of each heat exchanger module (1) is performed uniformly. After the low-temperature economizer is filled with water, the exhaust valve (501) of the exhaust system pipeline is closed, and the sewage valve (402) of the inlet and outlet large headers of the low-temperature economizer and the sewage valve (403) of the heat exchanger module header are opened. When the low-temperature economizer is shut down, the inlet main pipe main valve (201) and the outlet main pipe main valve (301) are closed, and the sewage system main pipe main valve (401) is opened to discharge water; After the water is drained, the heat exchanger module inlet pipeline branch valve (202) is kept open, the heat exchanger module outlet pipeline branch valve (302) is closed, the compressed air main pipe main valve (601) is opened, and then the compressed air branch pipe branch valves (602) are opened in sequence to perform the air-filled water draining operation on the heat exchanger module (1) to ensure that the water is drained from each heat exchanger module (1); Close the inlet main pipe valve (201) and the outlet main pipe valve (301), wait, and observe that the pressure drop detected by the pressure transmitter (9) is greater than or equal to the preset pressure drop, indicating that the low-temperature economizer is leaking as a whole; When the low-temperature economizer as a whole leaks, the inlet main pipe valve (201) is opened to restore the water side pressure of all heat exchanger modules (1) to normal, and all heat exchanger module inlet pipeline branch valves (202) and heat exchanger module outlet pipeline branch valves (302) are closed. When the pressure detected by any pressure transmitter (9) drops, it means that the heat exchanger module (1) corresponding to the pressure transmitter (9) is leaking.

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