How to operate the outlet valve and anti-surge valve when starting a centrifugal compressor

1. The main reason for closing the outlet valve at startup is to prevent the compressor from being subjected to excessive load during start-up. If the outlet valve is open at startup, the compressor must compress the entire system, which requires greater driving force and higher energy consumption. Meanwhile, closing the discharge valve allows the compressor to operate within a smaller internal circulation system, which helps gradually increase the compressor speed until the operating parameters are reached. At this point, although the compressor has flow, it is mainly internal circulation flow, resulting in relatively low power. The opening of the anti-surge valve (commonly referred to as an anti-surge device) is intended to prevent surge during operation at low flow rates, that is, to avoid compressor vibration or stability issues caused by insufficient flow. 2. If the inlet and outlet valves are opened simultaneously at startup while the anti-surge valve is not activated, the compressor may be exposed to the full system pressure, which places a heavy load on the motor and the mechanical components of the compressor, potentially leading to equipment damage or premature wear. Meanwhile, without using anti-surge valves, compressors are prone to unstable operation at low loads, such as surging, which can lead to poor efficiency and equipment damage. 3. The correct startup process is roughly as follows: – Ensure that there are no abnormalities in the system, and check that all devices are in a condition suitable for startup. - Open the inlet valve and close the outlet valve; at the same time, open the anti-surge valve to ensure a smooth start-up of the compressor under low flow rates and light load conditions. - Start the compressor and gradually accelerate it to the target speed. - After the compressor reaches its stable operating speed, gradually close the anti-surge valve, and then slowly open the outlet valve to allow the compressor to start supplying air to the system. - Monitor system parameters such as pressure and temperature to ensure normal operation. The purpose of the above operations is to ensure that the compressor starts smoothly under minimal load, thereby avoiding potential risks and damage to the equipment that might result from suddenly being subjected to high loads. Additionally, this helps protect the compressor from surging, which could otherwise shorten its lifespan and reduce its efficiency. .

Additionally, regarding this issue, it is best to formulate corresponding “operating procedures for positions” based on the actual needs on site. The minimum starting load condition for a centrifugal compressor is with the suction slightly open and the discharge fully open. As for the outlet valve, it usually has a check valve. If there is pressure in the system, but no pressure applied that exceeds the system pressure, it is equivalent to the outlet valve remaining closed. Gaseous media that usually have no economic value, or are non-toxic and not flammable or explosive, can be vented; otherwise, a circulation system must be installed with the circulation valves opened fully. For reference.