The compressor already has an anti-surge valve, so why is a vent valve needed as well?
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Recently, I was working on designing a control system for a carbon dioxide compressor. The flow diagram provided by the equipment manufacturer showed that the compressor consisted of two cylinders: the low-pressure cylinder was divided into two sections, while the high-pressure cylinder had one section. There are three paragraphs in total. At the second-stage outlet, there is an anti-surge valve that returns to the first-stage inlet, but there is also a vent valve. The third-stage outlet has an anti-surge valve that returns flow to the third-stage inlet; simultaneously, the third-stage outlet is also equipped with a vent valve. Well, since there is backflow from the anti-surge valve. Why is an exhaust valve still needed? Is the relief valve there to release pressure when it gets too high? Then if the pressure is too high, can’t reversing the flow also reduce the pressure? Could it be that the anti-surge valve opens to allow backflow only when surge occurs? When the pressure is too high, should one simply open the relief valve to reduce the pressure? Were the surge valves used before for either backflow or venting? I’ve never come across a valve that has both a return valve and a vent valve.
What do you mean by zoning out? Is it used during nitrogen displacement?
A surge valve is used to protect the compressor, automatically venting it once surging occurs in the compressor.
I think: the check valve is used to balance pressure and prevent surging. The relief valve is used to control system pressure and prevent excessive pressure from damaging the equipment.
It has an existing anti-surge valve. There is also a vent valve that prevents surge by returning flow to the inlet, while the vent valve releases flow to the atmosphere.
The anti-surge valve opens when pressure and flow are low, thereby protecting the compressor from excessive vibration. The relief valve is used to control system pressure and prevent it from rising too high, which could damage the equipment.
Everyone does their own thing; it’s not the same thing, and the name itself makes that clear.
It depends on the manufacturing requirements. Some have only anti-surge valves and no anti-air valves; design isn’t like an exam – it’s not that strict. You can ask the design manufacturer
The vacuum valve serves several purposes: 1. to vent air during startup, 2. to vent air during shutdown； 3. Vent when overpressure occurs. It’s important to understand that the function of the anti-surge valve in this post is not exactly the same as that of the vent valve.
This type of design has been encountered before; compressors with nitrogen or air as the working medium are equipped with vent valves. Some of these vent valves function as surge valves and are not suitable for handling full reflux conditions and overpressures, while others are used during shutdowns or during startup and commissioning
The answer is upstairs. Strictly speaking, it’s not called a vent valve but a safety valve; after all, not every type of gas can be vented directly, and in many cases it is necessary to use pipes to direct it to a flare or another location. Relief valves are generally used in emergency situations, such as sudden overpressure or during startup and shutdown ； The check valve mainly ensures the inlet flow rate and prevents surging ； The two have different functions; they cannot replace each other nor are they comparable