The method of preventing the refrigeration compressor of the cold storage from reversing

Update:26 Aug 2021
Summary:

Reverse rotation is strictly prohibited after the refri […]

Reverse rotation is strictly prohibited after the refrigeration compressor of the cold storage is stopped. When the compressor rotor is stationary, there is still a large amount of process gas remaining in the pipeline and has a certain pressure, and the compressor rotor stops rotating at this time, and the pressure in the compressor is lower than the pipeline pressure. At this time, if there is no check valve installed on the compressor outlet pipe or if the check valve is far away from the compressor outlet, the gas in the pipe will flow backward, causing the compressor to reverse, and it will also drive the steam turbine or electric motor and gear transmission. Wait for the rotor to reverse. The reverse rotation of the compressor unit rotor will destroy the normal lubrication of the bearing, change the force of the thrust bearing, and even cause the loss of the thrust bearing. The dry gas seal will also be damaged due to the reverse rotation of the compressor.

In order to prevent the compressor from reversing, several issues should be paid attention to:

1. A check valve must be installed on the compressor outlet pipeline and installed as close to the outlet flange as possible to minimize the distance between the check valve and the compressor outlet, so that the gas capacity in this section of the pipeline is reduced to Minimal, will not cause reversal.

2. According to the conditions of each unit, install vent valves, exhaust valves or recirculation pipelines. These valves should be opened in time when shutting down to remove the high-pressure gas from the compressor outlet to reduce the gas storage capacity in the pipeline.

3. The gas in the system may backflow when the compressor is stopped. High-pressure and high-temperature gas backflows back into the compressor, which can not only cause the compressor to reverse, but also burn out the bearings and seals.In order to effectively prevent the occurrence of the above-mentioned gas backflow accidents, the following two tasks must be done before speed reduction and shutdown:
   1) Open the vent valve or return valve to vent or return the gas.
   2) Close the check valve of the system piping securely. After completing the above work, gradually reduce the speed and shut down.

4. Increase research work. Due to the reform of the current wall materials, the design of a huge number of mixed structures has many new problems to study in wide construction. The increasingly complex functions of high-rise buildings require adjustment and continuous supplementation. In addition, some new issues need to be studied.