The Internal Leakage of the Thermal Power Plant Valve
In the development of thermal power plants, the internal leakage of the thermal system valves directly affects the development. Therefore, thermal power plants should actively know the causes of internal leakage of valves in the production process. Before production, timely check the corresponding equipment to clean up the dirt existing in them to ensure the automation of thermal power plant valves. In the process of starting the related equipment, the condensate cannot be recovered. It is necessary to strictly control the quality of the valve, do a good job in the operation of the valve in series, check the temperature of the valve regularly, and adjust the switch properly, which can prevent the valve from leaking. The influence of the valve's internal leakage on thermal power plants, judgment method, prevention and control measures of the valve internal leakage are explained in this article.
The internal leakage of the valve is a common problem in the production of current thermal power plants. Only by ensuring that the internal leakage does not occur for the valve, can energy be saved and energy waste reduced. Actively understanding the causes of the valve's internal leakage has a very important impact on the operation of the thermal power plant. Mastering the causes of the internal leakage of valves in thermal power plants and putting forward corresponding preventive measures can lay a good foundation for reducing the internal leakage of valves.
1. The influence of the internal leakage of the valve on thermal power plants
1.1 The impact on safety production
In the operation of thermal power plants, safety production has always been the key. If thermal power plants do not follow safe production, the economic benefits of thermal power plants cannot be effectively guaranteed. If there is internal leakage in the valve, the related equipment of the thermal power plant will not be able to be used. At present, the lack of corresponding safety measures cannot effectively guarantee the personal safety of maintenance personnel.
1.2 The impact on economic benefits
A leak in a valve in a thermal power plant can cause the chemicals produced in it to be released directly into the atmosphere, or the high-temperature treated substances are discharged into the condenser before being used, which in turn increases the heat load of the condenser and reduces the production efficiency of the thermal power plant. Because of the problem of internal leakage of the valve, the corresponding measures could not be provided in time, or it could not be repaired at first, resulting in poor work efficiency during the operation of the unit and being unable to obtain good economic benefits. For example, for overhead steel pipes, if there is an internal leak and it cannot be repaired in time, which will lead to an increase in the amount of coal burning. If the operation cannot be stopped in time, it will lead to the presence of cold water in the steam turbine, resulting in a high-security risk.
1.3 The impact on social image
In the process of operation, thermal power plants not only need to obtain corresponding economic benefits, but also bear the relevant responsibilities of social development. If the internal leakage happens for the valve, it will cause a part of the high-temperature and high-pressure water to be directly discharged into the atmosphere, thereby causing pollution to the environment. The internal leakage of the valve is also closely related to the management efficiency of thermal power plants, and low management efficiency is one of the reasons for the internal leakage of the valve.
2. Judgment methods of the internal leakage of the valve
Close the valve for 6 hours, and then use an infrared thermometer to measure the temperature of its valve stem. If the measured temperature is found to be greater than 70°C, it shows that the internal leakage of the valve occurs. This method is relatively accurate, but there will be some problems in the working process. First, it is the installation location of the pipeline. As a result, some valves will be affected by high temperatures, so that the temperature of the valve will be above 70°C even if there is no internal leakage. Therefore, other methods should be used. For example, if the valve is near the high temperature, then use the comparison between the high side and the high discharge temperature to know whether there is an internal leakage on the high side. Second, in the case of the drain gates being connected side by side, if the position of the last valve is close to the main pipe, the temperature of the other valves will exceed 70°C as long as the internal leakage occurs for one of the pipes. Therefore, for judging the internal leakage of these valves, the corresponding method should be used to ensure that the internal leakage is checked through the temperature measurement of the valve stem.
Measures to prevent internal leakages of valves are as follows:
1. Flushing the pipe
During valve inspection, it is common to find scratches on the valve. During the operation of power plant units, it is often found that the valve does not leak before opening, but leaks occur during operation, which are all caused by impurities in the pipeline. For example, valves are closed during operation for water gates below the boiler, and they can only be opened after the boiler discharges water under normal circumstances. Before the boiler enters the water, it is closed under the condition of no pressure, whether it is in the state of opening the valve or in the state of closing the valve. Under the condition of no pressure, the substances existing in the pipeline cannot be removed in time, and some impurities will remain in it, which may damage the sealing surface in the process of closing the valve, and lead to internal leakages of the valve. Under normal circumstances, all valves in thermal power systems of thermal power plants should be flushed under pressure before starting, and the generated wastewater is directly discharged to the corresponding position.
2. The filter being in a good condition
In the thermal system of a thermal power plant, it is a very critical step to prevent impurities from entering the thermal system only by ensuring that the filter is in a good condition. The thermal system filter screen of a thermal power plant refers to the filter screen in the front water supply, main water supply and other departments. The filters in these parts should be cleaned in time during use, and the damaged filters should be replaced in time so as to effectively prevent impurities from entering them.
3. Calibrating the electric valve
In order to reduce the internal leakage of electric valves, some electric valves which cannot be opened automatically should be adjusted to automatic mode to ensure that no angle is reserved for the valve. For some electric valves that have been able to start automatically, no matter what state they are in, they can be opened automatically, so the tightness of the electric valve should be ensured.
4. Not recycling unqualified condensate
In the process of starting the unit, if the superheater of the boiler is pressurized, the welding slag impurities in the steam system inside the boiler will flow into the main steam pipe of the steam turbine. Impurities entering the high side and superheater will flow to the condenser. In this way, the quality of the condensate water will not meet the standard. In the process, the condensate water will be discharged to the corresponding position, and the water volume in the condenser will be increased in time to ensure that the water quality of the condenser can meet the corresponding standards. After the water quality in the condenser meets the standard, the water in the condenser can be recycled in time.
5. Maintenance of the check valve
In the process of overhauling the valve, the method of pressing red lead can be used to check the degree of integration of the valve, and checking one by one should be carried out. If it is found that the quality of the valve does not meet the standard after overhauling, the valve cannot be used and must be repaired again. The valve of the thermal system should also be measured. The purpose of this is to better understand the internal leakage of the valve during operation, and to provide corresponding help for closing the valve for maintenance. In the process of measuring the temperature of the valve, it is generally measured once a week.
6. Standardizing the valve operation method
In the process of opening and closing the valve, some shut-off valves can only be fully opened or fully closed under normal conditions, and cannot be left in a half-open or half-closed state to ensure that internal leakages will not occur in the valve. In some of these pipelines, water gates should be set up. In order to prevent the internal leakage of the valves, the water gate should be opened once before opening, and then it should be opened again; the water volume can be effectively adjusted by twice opening. Open the valve once and then open it again to protect the equipment.
7. Closing the valve well after the unit being started
After starting the unit, it is necessary not only to ensure that the moving door is closed, but also to evacuate its electric water door; manually depressurize it after closing the electric door. After 4 hours, the temperature needs to be measured, and the result is used to judge whether the valve is closed well. If it is found that the temperature of the valve has dropped in the process, but it has not dropped to the ambient temperature, it is necessary to retighten it again, so that the valve can be closed.
Conclusion
All in all, the energy consumption of thermal power plants can be well reduced by controlling valves, and taking preventive measures against internal leakages of valves is also the main method to reduce internal leakages. Only effective prevention can reduce the leakage of valves and improve the economic benefits of thermal power plants.
The internal leakage of the valve is a common problem in the production of current thermal power plants. Only by ensuring that the internal leakage does not occur for the valve, can energy be saved and energy waste reduced. Actively understanding the causes of the valve's internal leakage has a very important impact on the operation of the thermal power plant. Mastering the causes of the internal leakage of valves in thermal power plants and putting forward corresponding preventive measures can lay a good foundation for reducing the internal leakage of valves.
1. The influence of the internal leakage of the valve on thermal power plants
1.1 The impact on safety production
In the operation of thermal power plants, safety production has always been the key. If thermal power plants do not follow safe production, the economic benefits of thermal power plants cannot be effectively guaranteed. If there is internal leakage in the valve, the related equipment of the thermal power plant will not be able to be used. At present, the lack of corresponding safety measures cannot effectively guarantee the personal safety of maintenance personnel.
1.2 The impact on economic benefits
A leak in a valve in a thermal power plant can cause the chemicals produced in it to be released directly into the atmosphere, or the high-temperature treated substances are discharged into the condenser before being used, which in turn increases the heat load of the condenser and reduces the production efficiency of the thermal power plant. Because of the problem of internal leakage of the valve, the corresponding measures could not be provided in time, or it could not be repaired at first, resulting in poor work efficiency during the operation of the unit and being unable to obtain good economic benefits. For example, for overhead steel pipes, if there is an internal leak and it cannot be repaired in time, which will lead to an increase in the amount of coal burning. If the operation cannot be stopped in time, it will lead to the presence of cold water in the steam turbine, resulting in a high-security risk.
1.3 The impact on social image
In the process of operation, thermal power plants not only need to obtain corresponding economic benefits, but also bear the relevant responsibilities of social development. If the internal leakage happens for the valve, it will cause a part of the high-temperature and high-pressure water to be directly discharged into the atmosphere, thereby causing pollution to the environment. The internal leakage of the valve is also closely related to the management efficiency of thermal power plants, and low management efficiency is one of the reasons for the internal leakage of the valve.
2. Judgment methods of the internal leakage of the valve
Close the valve for 6 hours, and then use an infrared thermometer to measure the temperature of its valve stem. If the measured temperature is found to be greater than 70°C, it shows that the internal leakage of the valve occurs. This method is relatively accurate, but there will be some problems in the working process. First, it is the installation location of the pipeline. As a result, some valves will be affected by high temperatures, so that the temperature of the valve will be above 70°C even if there is no internal leakage. Therefore, other methods should be used. For example, if the valve is near the high temperature, then use the comparison between the high side and the high discharge temperature to know whether there is an internal leakage on the high side. Second, in the case of the drain gates being connected side by side, if the position of the last valve is close to the main pipe, the temperature of the other valves will exceed 70°C as long as the internal leakage occurs for one of the pipes. Therefore, for judging the internal leakage of these valves, the corresponding method should be used to ensure that the internal leakage is checked through the temperature measurement of the valve stem.
Measures to prevent internal leakages of valves are as follows:
1. Flushing the pipe
During valve inspection, it is common to find scratches on the valve. During the operation of power plant units, it is often found that the valve does not leak before opening, but leaks occur during operation, which are all caused by impurities in the pipeline. For example, valves are closed during operation for water gates below the boiler, and they can only be opened after the boiler discharges water under normal circumstances. Before the boiler enters the water, it is closed under the condition of no pressure, whether it is in the state of opening the valve or in the state of closing the valve. Under the condition of no pressure, the substances existing in the pipeline cannot be removed in time, and some impurities will remain in it, which may damage the sealing surface in the process of closing the valve, and lead to internal leakages of the valve. Under normal circumstances, all valves in thermal power systems of thermal power plants should be flushed under pressure before starting, and the generated wastewater is directly discharged to the corresponding position.
2. The filter being in a good condition
In the thermal system of a thermal power plant, it is a very critical step to prevent impurities from entering the thermal system only by ensuring that the filter is in a good condition. The thermal system filter screen of a thermal power plant refers to the filter screen in the front water supply, main water supply and other departments. The filters in these parts should be cleaned in time during use, and the damaged filters should be replaced in time so as to effectively prevent impurities from entering them.
3. Calibrating the electric valve
In order to reduce the internal leakage of electric valves, some electric valves which cannot be opened automatically should be adjusted to automatic mode to ensure that no angle is reserved for the valve. For some electric valves that have been able to start automatically, no matter what state they are in, they can be opened automatically, so the tightness of the electric valve should be ensured.
4. Not recycling unqualified condensate
In the process of starting the unit, if the superheater of the boiler is pressurized, the welding slag impurities in the steam system inside the boiler will flow into the main steam pipe of the steam turbine. Impurities entering the high side and superheater will flow to the condenser. In this way, the quality of the condensate water will not meet the standard. In the process, the condensate water will be discharged to the corresponding position, and the water volume in the condenser will be increased in time to ensure that the water quality of the condenser can meet the corresponding standards. After the water quality in the condenser meets the standard, the water in the condenser can be recycled in time.
5. Maintenance of the check valve
In the process of overhauling the valve, the method of pressing red lead can be used to check the degree of integration of the valve, and checking one by one should be carried out. If it is found that the quality of the valve does not meet the standard after overhauling, the valve cannot be used and must be repaired again. The valve of the thermal system should also be measured. The purpose of this is to better understand the internal leakage of the valve during operation, and to provide corresponding help for closing the valve for maintenance. In the process of measuring the temperature of the valve, it is generally measured once a week.
6. Standardizing the valve operation method
In the process of opening and closing the valve, some shut-off valves can only be fully opened or fully closed under normal conditions, and cannot be left in a half-open or half-closed state to ensure that internal leakages will not occur in the valve. In some of these pipelines, water gates should be set up. In order to prevent the internal leakage of the valves, the water gate should be opened once before opening, and then it should be opened again; the water volume can be effectively adjusted by twice opening. Open the valve once and then open it again to protect the equipment.
7. Closing the valve well after the unit being started
After starting the unit, it is necessary not only to ensure that the moving door is closed, but also to evacuate its electric water door; manually depressurize it after closing the electric door. After 4 hours, the temperature needs to be measured, and the result is used to judge whether the valve is closed well. If it is found that the temperature of the valve has dropped in the process, but it has not dropped to the ambient temperature, it is necessary to retighten it again, so that the valve can be closed.
Conclusion
All in all, the energy consumption of thermal power plants can be well reduced by controlling valves, and taking preventive measures against internal leakages of valves is also the main method to reduce internal leakages. Only effective prevention can reduce the leakage of valves and improve the economic benefits of thermal power plants.
