CN106969946B

CN106969946B - Condensate sampling method and device for detecting leakage of condenser

Info

Publication number: CN106969946B
Application number: CN201710269814.9A
Authority: CN
Inventors: 张维科; 李俊菀; 刘玮
Original assignee: Xian Thermal Power Research Institute Co Ltd
Current assignee: Xian Thermal Power Research Institute Co Ltd
Priority date: 2017-04-21
Filing date: 2017-04-21
Publication date: 2023-06-23
Anticipated expiration: 2037-04-21
Also published as: CN106969946A

Abstract

According to the structural characteristics of condensers of different power plants, a special sampler is arranged in each water chamber hot well of the condenser, and a vacuum sampling water pump is used for pumping the condensed water of each water chamber of the condenser out of the condenser, so that a representative water sample is provided for detecting the leakage of the condenser, which water chamber is leaked can be rapidly and accurately diagnosed, and an accurate and reliable decision basis is provided for processing the leakage of the condenser without stopping the operation of the power plant; the method and the device have the characteristics of strong sampling representativeness and high reliability, and are suitable for sampling the condensed water during the leak detection in the operation of the condenser heat exchange tube of the seawater and fresh water cooling power plant.

Description

Condensate sampling method and device for detecting leakage of condenser

Technical Field

The invention relates to the technical field of power generation, in particular to a condensate sampling method and device for detecting leakage of a condenser.

Background

Leakage in the operation of a heat exchange tube of a condenser is one of the important hidden troubles which plague the safe operation of a power plant for a long time. When the condenser heat exchange tube leaks, the condensed water is polluted, so that the quality of the water vapor of the thermodynamic system is deteriorated, serious corrosion and scaling are caused in a short time of thermodynamic system equipment, the safe operation of a unit is threatened, even the unit provided with the condensed water refined desalting device can only last for a plurality of hours at most, and if the leaking position cannot be found and treated within the plurality of hours, the leakage point can only be found and treated by emergency shutdown. The leakage detection device of the condenser plays an important role in diagnosing whether the condenser leaks or not and positioning the position of a leakage point.

Because the impurity ion concentration of the cooling water flowing in the heat exchange tube of the condenser is far higher than that of the condensed water condensed by the steam in the heat well of the condenser, the most obvious characteristic of the leakage of the heat exchange tube of the condenser is that the impurity ion concentration in the condensed water is increased, and the leakage degree of the cooling water is represented by the increase degree of the impurity ion concentration. Therefore, detecting the concentration of impurity ions in the condensed water is an important parameter for judging whether the condenser heat exchange tube leaks or not and calculating the leakage rate.

The leakage detecting device of the condenser has great economic significance for accurately judging leakage points and shortening leakage detecting time. Problems of the existing condenser leakage detection device are that: 1) Sampling representativeness is poor, sampling points are arranged at two ends of a condenser of each water chamber, one is in a water collecting tank (only the leakage of a pipe orifice of the condenser can be detected), and the other is at the bottom surface of a thermal well close to the pipe end (only the leakage of the pipe orifice and a heat exchange pipe close to the pipe orifice can be detected); 2) Water samples are not pumped out frequently. Because the condenser operates under vacuum, the general operating pressure is about 4.9kPa (absolute pressure), the vacuum degree is very high, if the water sample is to be continuously and stably extracted, the requirements on the installation height of a sampling pump, a sampling pipeline, a valve, a pump and the like are very high, and the water sample cannot be extracted as long as a certain link has a problem.

Therefore, a condensate sampling method and a condensate sampling device special for detecting leakage of the condenser heat exchange tube are urgently needed in a power plant, a representative condensate water sample is guaranteed to be continuously extracted from a condenser hot well for a long time, and accurate and rapid detection of the leakage of the condenser heat exchange tube is realized.

Disclosure of Invention

The invention aims to provide a condensate sampling method and device special for detecting leakage of a condenser, which can ensure that all the condenser water chambers are subjected to full-coverage sampling, the sampling has obvious representativeness, and the problem of error detection and diagnosis results of the condenser caused by poor water sample representativeness is fundamentally solved.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a sampling method for the condensed water used for detecting the leakage of condenser features that a sampler is horizontally arranged along the length direction of condenser tube, its installed position is the downstream of the condensed water flowing direction of each water chamber of condenser and is below the lowest water level line of condenser, a sampling hole is made on sampler, and the water sample is taken out from the hot well of condenser by vacuum sampling water pump.

The distance between sampling holes of the sampler is 0.3-0.8 meter, the number of the sampling holes is an integer obtained by dividing the length of the sampler by 0.5, the aperture range of the sampling holes is 1/3-1/10 of the inner diameter of the sampling tube, and the sampling holes gradually become smaller along the water flow direction in the sampler.

In order to realize the method of the invention, the condensed water sampling device for detecting the leak of the condenser comprises a main loop and a branch; the main loop is composed of a sampler 1 arranged in a condenser hot well, a main pipeline 13 connected with the sampler 1, a sampling primary door 2, a sampling secondary door 3, a Y-type filter 4, a flow monitor 5, a water inlet tank 6, a pump inlet valve 7, a sampling pump 8, a check valve 9, a pump outlet valve 10, a water return regulating valve 11 and a water return valve 12 which are sequentially arranged on the main pipeline 13, wherein the water return valve 12 is connected with the condenser; the branch is composed of a branch sampling valve 15 which is connected with a pump outlet valve 10 through a tee joint and is used for conveying a water sample which is branched by the tee joint after passing through the pump outlet valve 10 to a condenser leak detection on-line chemical instrument or a manual sampling place through a branch pipeline 14; after being led out from a condenser heating well through a sampler 1, a main loop water sample sequentially flows through a sampling primary door 2, a sampling secondary door 3, a Y-shaped filter 4, a flow monitor 5, a water inlet tank 6, a pump inlet valve 7, a sampling pump 8, a check valve 9, a pump outlet valve 10, a water return regulating valve 11, a water return valve 12 and a main pipeline 13 connected between the water return regulating valve and the water return valve, and finally returns to the condenser; the branch water sample is branched by a tee joint and then is conveyed to a condenser leak detection on-line chemical instrument or a manual sampling position from a pump outlet valve 10 through a branch pipeline 14 and a branch sampling valve 15.

The water inlet tank 6 is a cylindrical container which is vertically arranged, the top and the bottom of the water inlet tank are designed into hemispheres, water is inlet and outlet from the side, the top of the water inlet tank is communicated with the steam side of the condenser through an exhaust pipeline 16, and exhaust is controlled through an exhaust valve 17 to exhaust air in a sampling pipeline before starting; the bottom is provided with a drain valve 18 for draining water and sediment when inactive.

A vacuum pressure gauge 19 is arranged on the main pipeline 13 between the water inlet tank 6 and the pump inlet valve 7 and is used for monitoring the inlet pressure of the sampling pump 8; a pressure gauge 20 is arranged on the main pipeline 13 between the pump outlet valve 10 and the return water regulating valve 11 and is used for monitoring the water sample pressure in front of the bypass sampling valve 15.

As an optimal scheme, all manual valves in a pipeline system in front of the sampling pump are through-diameter vacuum ball valves so as to reduce the resistance of the pipeline system; the connection of the valve and the pipeline adopts socket welding so as to improve the tightness of the system.

As a preferable scheme, the sampling pump 8 is a magnetically driven gear pump, and each path of water sample is independently sampled, so that the lag time of the water sample is reduced, and the cross contamination of the water sample is avoided.

In order to ensure that the sampling line fills with water before the sampling pump 8 is started, a flow monitor 5 is provided in front of the water inlet tank 6. When water injection is started, the flow monitor displays the flow of the water sample; when filled with water, the flow monitor will show that the water sample is not flowing.

Compared with the prior art, the invention has the following advantages:

1. because the sampler runs through whole condenser pipe length direction, and concrete mounted position is the low reaches of each hydroecium condensate water flow direction of condenser and under condenser operation minimum water line, simultaneously because the aperture of sampler trompil, hole interval, trompil quantity etc. all are according to hydrodynamic design, can guarantee that the water sample flow that gets into each sample hole is close, consequently can guarantee to the full coverage sample to every condenser hydroecium, the sample has apparent representativeness, fundamentally has solved the condenser leak hunting diagnostic result mistake because the water sample representativeness is poor and leads to.

2. The sampling system is reasonable in design, small in resistance and low in requirement on the installation height of the sampling pump.

3. The design of the water inlet tank is ingenious, the pipeline system is ensured to be filled with water before the sampling pump is started and the air in the system is exhausted, and the accumulated water and sediment in the water tank are ensured to be exhausted when the sampling pump is stopped.

4. The flow of the sampling pump is smaller, the system resistance is smaller, the sampling pipeline is thinner, the valve size is smaller, and therefore, the total cost of equipment is lower.

Drawings

FIG. 1 is a schematic diagram of a condensate sampling apparatus for condenser leak detection.

Fig. 2 is a schematic view of the structure of the water inlet tank.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings.

Preparation work before starting: referring to fig. 1, prior to start-up of the sampling system, all valves are checked and confirmed to be in a closed state. Then, the sampling primary door 2, the sampling secondary door 3 and the exhaust valve 17 at the top of the water inlet tank 6 are opened, water injection and exhaust of the sampling system pipeline are carried out, the indication state of the flow monitor 5 is observed, and when the flow monitor indicates that the water sample does not flow, the front pipeline of the sampling pump 8 is full of water, and the gas is exhausted. The top exhaust valve 17 of the intake tank 6 is closed.

The operation steps are as follows: referring to fig. 1, after water injection and exhaust work is finished, a pump inlet valve 7, a water return regulating valve 11 and a water return valve 12 are opened, a sampling pump 8 is started, a pressure gauge 19 indicating value before the pump inlet valve 7 is observed to be larger than pump inlet pressure required by the sampling pump 8, then a pump outlet valve 10 is gradually opened, condensed water in a condenser hot well enters the sampler 1 from a sampling hole on the sampler 1, and sequentially flows through a sampling primary door 2, a sampling secondary door 3, a Y-type filter 4, a current monitor 5, a water inlet tank 6, a pump inlet valve 7, a sampling pump 8, a check valve 9, a pump outlet valve 10, a water return regulating valve 11 and a water return valve 12 to flow back to the position above the highest liquid level of the condenser hot well, so that a condensed water sample main loop is established; gradually closing the water return regulating valve 11, indicating the pressure gauge 20 in front of the water return regulating valve 11 to be 0.2-0.4 MPa, and then slowly opening the branch sampling valve 15 to ensure that the water sample flow meets the requirements of on-line chemical instrument measurement or manual sampling. During operation, 4 paths of water samples are independently sampled, so that the lag time of the water samples is reduced, and cross contamination of the water samples is avoided.

The operation steps of shutdown are as follows: referring to fig. 1, the bypass sampling valve 15 is closed, then the power supply to the sampling pump 8 is turned off, and finally all other valves are turned off.

As shown in fig. 2, the water inlet tank 6 is a cylindrical container which is vertically installed, the top and the bottom of the water inlet tank are designed into hemispheres, water is inlet and outlet from the side, the top of the water inlet tank is communicated with the steam side of the condenser through an exhaust pipeline 16, and the exhaust is controlled through an exhaust valve 17 to exhaust air before starting the sampling system; the bottom is provided with a drain valve 18 for draining water and sediment when inactive.

Claims

1. A condensate sampling device for condenser leak hunting, its characterized in that: comprises a main loop and a branch circuit; the main loop is composed of a sampler (1) arranged in a condenser hot well, a main pipeline (13) connected with the sampler (1), a sampling primary door (2), a sampling secondary door (3), a Y-shaped filter (4), a flow monitor (5), a water inlet tank (6), a pump inlet valve (7), a sampling pump (8), a check valve (9), a pump outlet valve (10), a water return regulating valve (11) and a water return valve (12) which are sequentially arranged on the main pipeline (13), wherein the water return valve (12) is connected with the condenser;

horizontally arranging a sampler along the length direction of a condenser pipe, wherein the concrete installation position is downstream of the condensation water flow direction of each water chamber of the condenser and is below the lowest water level line of the condenser operation, sampling holes are formed in the sampler, and a sampling pump is used for taking out a water sample from a condenser hot well through the sampler;

the distance between sampling holes of the sampler is 0.3-0.8 meter, the number of the sampling holes is an integer obtained by dividing the length of the sampler by 0.5, the aperture range of the sampling holes is 1/3-1/10 of the inner diameter of the sampling tube, and the sampling holes gradually become smaller along the water flow direction in the sampler;

the water inlet tank (6) is a cylindrical container which is vertically arranged, the top and the bottom of the water inlet tank are designed into hemispheres, water is inlet and outlet from the side, the top of the water inlet tank is communicated with the steam side of the condenser through an exhaust pipeline (16), and exhaust is controlled through an exhaust valve (17) to exhaust air in a sampling pipeline before starting; the bottom is provided with a water drain valve (18) for draining accumulated water and sediment when the device is not in use.

2. The condensate sampling apparatus for condenser leak detection of claim 1, wherein: the branch consists of a branch sampling valve (15) which is connected with a pump outlet valve (10) through a tee joint and is used for conveying a water sample which is branched by the tee joint after passing through the pump outlet valve (10) to a condenser leak detection on-line chemical instrument or a manual sampling position through a branch pipeline (14);

after being led out from a condenser hot well through a sampler (1), a main loop water sample sequentially flows through a sampling primary door (2), a sampling secondary door (3), a Y-shaped filter (4), a flow monitor (5), a water inlet tank (6), a pump inlet valve (7), a sampling pump (8), a check valve (9), a pump outlet valve (10), a water return regulating valve (11), a water return valve (12) and a main pipeline (13) connected with the water return valve, and finally returns to the condenser; after the branch water sample is split by a tee joint, the branch water sample is conveyed to a condenser leak detection on-line chemical instrument or a manual sampling place from a pump outlet valve (10) through a branch pipeline (14) and a branch sampling valve (15);

the sampling pump (8) is a gear pump driven by magnetic force.

3. The condensate sampling apparatus for condenser leak detection of claim 1, wherein: a vacuum pressure gauge (19) is arranged on the main pipeline (13) between the water inlet tank (6) and the pump inlet valve (7) and is used for monitoring the inlet pressure of the sampling pump (8); a pressure gauge (20) is arranged on the main pipeline (13) between the pump outlet valve (10) and the return water regulating valve (11) and is used for monitoring the water sample pressure in front of the bypass sampling valve (15).

4. The condensate sampling apparatus for condenser leak detection of claim 1, wherein: in order to ensure that the sampling pipeline is filled with water before the sampling pump (8) is started, a flow monitor (5) is arranged in front of the water inlet tank (6).