QZJ Series Water-ring Vacuum Pump Set

QZJ Series Water-ring Vacuum Pump Set

Application

The QZJ series two-stage conical water ring vacuum pump complete set is designed to establish and maintain the low back pressure of the steam turbine unit and the vacuum of the condenser. When the vacuum system is operating normally, it constantly extracts the non-condensable gas that leaks into the steam turbine and condenser through different channels. The size of the water ring vacuum pump selected for the condenser is determined by the amount of dry air leakage from the condenser. If the dry air leaking from the condenser is not extracted in time, the operational stability of the steam turbine unit is difficult to guarantee. Moreover, the better the vacuum, the higher the power generation, achieving the goal of energy conservation and consumption reduction.

Therefore, the condenser vacuum system is of great significance to the operation of power plants, directly affecting the economic efficiency of the power plants and the stability of the system operation. At present, many enterprises have their own power plants, waste-to-energy plants and thermal power plants. The vacuum systems are generally water injection and gas extraction systems, steam injection systems, etc. The adoption of these systems is all based on the old process design from the past, and their maintenance and repair are very inconvenient. The new power plant designs all directly adopt the new type of water ring vacuum system. Therefore, the conditions for selecting a condenser vacuum pump are:

1) Based on a large number of successful application experiences in China;

2) The vacuum pump should have sufficient suction margin. Even if the sealing parts of the condenser system age and cause an increase in air leakage, it can still maintain the optimal negative pressure of the condenser.

3) Different manufacturers provide equipment with different leakage volumes. The installation level of the equipment also varies, which can lead to different leakage volumes. If the vacuum pump has sufficient margin, these risks can be mitigated.

4) The pumping capacity of the vacuum pump should meet the requirements of peak shaving conditions in winter as well as the pumping capacity and vacuum degree during full-load operation in summer, to avoid the situation where the backup pump also has to be put into operation due to improper selection.

Product Features

1. Vacuum pump:

① The selected global premium brand: NASH. Stable performance and reliable quality. It is widely used in industries such as power, chemical engineering, papermaking, petrochemicals, food, pharmaceuticals, metallurgy, electronics, environmental protection, and mining.

② The liquid ring vacuum pump is a simple-structured and reliable volumetric variable pump, featuring: A. The ability to handle almost all gases and vapors; B. It is almost isothermal compressed, and no lubrication is required in the working chamber, thus causing no pollution. C. It can handle a small amount of entrainment liquid. D. Easy to maintain and highly reliable; E. Low noise, almost no vibration; F. A wide range of material options, basically suitable for all occasions; G. Cavitation protection is provided as a standard configuration; H. Integrated sewage discharge I. The rotating parts have no features such as metal contact.

③ It is suitable for the treatment and extraction of both dry and moist air. It can handle the carried liquid under normal conditions. This vacuum pump can be used in all situations that require a coarse vacuum ranging from 15mbr to 900mbr. The suction gas temperature is generally between -10°C and +80°C, and the working fluid temperature is between 0 and 35°C. By changing the structural materials, the pump can be used to draw corrosive gases or use corrosive liquids as the working fluid. If non-water working fluid is adopted, the performance of the pump will be different.

2. Instruments and meters

① Vacuum gauge - The vacuum gauge selected is an anti-vibration vacuum gauge with stable performance.

② It adopts brand vacuum switches and is controllable. The vacuum is generally controlled at -0.095MPa and -0.085MPa. Adjust the vacuum required by the control system on site and control the start and stop of the liquid ring vacuum.

③ The vapor-liquid separator is equipped with an automatic liquid replenishment system to promptly replenish the cooling medium required by the vacuum system. The liquid replenishment solenoid valve is interlocked with the high and low liquid level controllers for control.

④ The exhaust pipeline adopts pneumatic solenoid valves to achieve automatic opening and closing.

3. Two-stage cone vacuum pump

The water ring vacuum system uses circulating water, featuring low water consumption and no steam consumption.

② Neither the pump body nor the pipes of the water ring vacuum system will scale like those of the water jet pump (this is especially obvious in areas with poor water quality). Therefore, the use of the water ring vacuum system greatly reduces the maintenance workload.

③ The water ring vacuum system is easy to operate, can be managed unattended, and can be remotely controlled by DCS.

④ The water ring vacuum system is convenient for maintenance.

⑤ The water ring vacuum system takes up a small area and is easy to install and connect.

⑥ The water ring vacuum system is the preferred choice for the vacuum system renovation and construction of condensers in power plants.

The vacuum degree of a water ring vacuum system can generally reach -93 kpa or above. The specific vacuum degree is related to the on-site environment and the temperature of the cooling medium.

Principle Explanation

There are two air extraction interfaces on each of the high and low pressure side condenser shells, and their positions are determined by the condenser manufacturer. There is an air extraction connection pipe connecting the condensers on the high and low pressure sides. The gas drawn in by the condenser passes through the water seal valve, the gas suction port and the start butterfly valve to enter the vacuum pump. The gas discharged by the vacuum pump enters the steam-water separator through the pipeline. The separated gas is discharged into the atmosphere from the gas outlet through the check valve. The separated water enters the heat exchanger together with the supplementary water passing through the water level regulator. The working water after heat exchange and cooling enters the pump chamber through the water inlet of the vacuum pump. On the one hand, it causes the condensable part of the gas about to be drawn into the vacuum pump to condense, thereby enhancing the suction capacity of the vacuum pump. On the other hand, maintain the water circulation of the vacuum pump and reduce the temperature inside the pump chamber. The cooling water for the heat exchanger adopts open water, which is provided by the circulating water pool of the power plant or tap water.

Technical Specification

Comparison of two-stage cone vacuum pumps with existing vacuum systems

■Above mentioned weight and size are for reference only, the specific data shall be as per the standard of real goods.