The refrigeration compressor is the heart of the entire refrigeration system and the most important in the refrigeration system. Its main function is to compress the low-temperature and low-pressure gas from the evaporator into high-temperature and high-pressure gas to provide the source power for the entire refrigeration cycle. When the rotor of the compressor is at rest, there is still a large amount of process gas remaining in the pipeline with a certain pressure. At this time, the rotor of the compressor stops rotating, and the internal pressure of the compressor is lower than the pressure of the pipeline. At this time, if there is no check valve installed on the compressor outlet pipeline or the check valve is far away from the compressor outlet, the gas in the pipeline will flow backwards, causing the compressor to reverse, and at the same time drive the steam turbine or electric motor and gear transmission Wait for the rotor to reverse. The reverse rotation of the rotor of the compressor unit will destroy the normal lubrication of the bearings, change the stress on the thrust bearings, and even cause the loss of the thrust bearings, and the dry gas seal will also be damaged due to the reverse rotation of the compressor.
In order to avoid reverse rotation of the compressor, several issues should be paid attention to:
1. A check valve must be installed on the outlet pipeline of the compressor, and it should be 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 pipeline can be reduced to Minimum, so as not to cause reversal.
2. According to the conditions of each unit, install vent valves, exhaust valves or recirculation pipelines. When shutting down, these valves should be opened in time to discharge the high-pressure gas at the outlet of the compressor to reduce the gas capacity stored in the pipeline.
3. The gas in the system may flow back when the compressor is shut down. The high-pressure and high-temperature gas will flow back into the compressor, which will not only cause the compressor to reverse, but also burn out the bearings and seals.
Due to the many accidents caused by gas backflow, it is very worth noting! In order to effectively prevent the occurrence of the above-mentioned accidents, the following two tasks must be done before reducing the speed and stopping:
1. Open the vent valve or return valve to vent or return the gas.
2. Securely close the check valve of the system pipeline. After doing the above work, gradually reduce the speed and stop.
Post time: Feb-15-2023