Rotary vane vacuum pump is the most important vacuum pumping equipment of condenser in power plant. Because most of the existing thermal power plants use wet cooling units, the configuration and application of rotary vane vacuum pump in wet cooling units are relatively mature. Air cooling technology can effectively solve the problem of thermal power generation in areas with rich coal resources but lack of water resources. Therefore, air cooling technology has been developed rapidly in China, especially in Sanbei area. The main difference between the direct air cooling unit and the conventional wet cooling unit is the cold end system. The direct air cooling unit uses ambient air instead of water as the cooling medium of the steam turbine exhaust. Therefore, the economic and stable operation of the cold end system of air-cooled unit is of great significance to the whole unit. In this way, the application of 2XZ direct drive rotary vane vacuum pump in the vacuum system of air cooling unit is very important.
Generally speaking, when selecting the type of rotary vane vacuum pump for the wet cooling unit, if the rotary vane vacuum pump can meet the performance of pumping dry air when maintaining the vacuum condition, it can generally meet the requirements of starting time. On the contrary, if the rotary vane vacuum pump can meet the requirements of starting conditions. This difference is due to the fact that the volume of vacuum system of air-cooled unit is larger than that of wet cooled unit.
How to select the type of 2XZ direct drive rotary vane vacuum pump?
1. The working pressure of vacuum pump should meet the requirements of limit vacuum and working pressure of vacuum equipment.
2. Select the working point of vacuum pump correctly.
3. Under its working pressure, the vacuum pump should be able to discharge all the gas produced in the process of vacuum equipment.
4. Combine the vacuum pump correctly. Because of the selective pumping of vacuum pump, sometimes selecting one pump can not meet the pumping requirements. Several pumps need to be combined to supplement each other to meet the pumping requirements.
5. Requirements of vacuum equipment for oil pollution.
6. Know the composition of the extracted gas, including no condensable vapor, particle dust, corrosiveness, etc. When selecting a vacuum pump, it is necessary to know the gas composition and select the corresponding pump for the extracted gas. If the gas contains steam, particles and corrosive gas, auxiliary equipment, such as condenser, dust remover, etc., shall be installed on the air inlet pipeline of the pump.
7. How does the oil vapor discharged from vacuum pump affect the environment. If the environment is not allowed to be polluted, the oil-free vacuum pump can be selected, or the oil vapor can be discharged to the outdoor.
8. Whether the vibration produced during the operation of vacuum pump affects the process and environment. If the process is not allowed, the pump without vibration shall be selected or anti vibration measures shall be taken.
The application of 2XZ direct drive rotary vane vacuum pump in the vacuum system of air-cooled unit is to control the pressure of air-cooled unit and exhaust unit respectively, and to optimize the vacuum of unit and provide economy by adding regulating valve on the vacuum extraction pipe of exhaust unit. In addition, a continuous exhaust system is installed on the vertical downcomer of condensate return water from the air cooling unit to the exhaust unit to prevent severe vibration of the vertical downcomer caused by steam gas mixing, which is conducive to the safe and stable operation of the unit.