Questions about reciprocating compressors
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I hope the experts here can help me understand why, when some compressors start up, both the inlet and outlet valves are closed while the reflux valve is opened; whereas in other cases, both the inlet and outlet valves are opened along with the reflux valve. My conclusion is as follows: compressors equipped with a unloader have both inlet and outlet valves opened along with the reflux valve, so that the load is reduced to 0, while compressors without a unloader have both inlet and outlet valves closed, with the reflux valve still being opened. Normally, the load options for compressors equipped with unloading devices are 0, 50, and 100. But for Buchhard’s reciprocating compressors, the load options are only 50, 75, and 100. What should be done? Should the inlet and outlet valves as well as the return valve be opened to select 50? Won’t this cause an excessive current?
The inlet and outlet valves should all be fully open when starting the machine under no-load conditions
But there isn’t any 0% load among the loads; the minimum is 50% load. How can this be explained?
Some compressors are equipped with an inlet valve that serves as the first stage of connection to the system, along with an outlet valve; once the pressure reaches the level required by the system, the outlet valve is opened to feed fluid into the system stage by stage. Pressure regulation is achieved through circuit valves, also known as return valves. It should be noted that the machine cannot be started under load.
I know that. But Buchhard’s compressors only have load capacities of 50, 75, and 100 – how is it possible to achieve start-up at zero load?
The check valve gradually closes during loading; just remember that.
So at its minimum load, this compressor operates at 50%; when the inlet, outlet, and return valves are opened, if it starts at 50%, it’s not starting under no-load conditions. Isn’t it said that reciprocating compressors should start under no-load conditions?
What will the outlet pressure be when the reflux valve is set at 50% open? Has it reached the rated pressure? No-load starting is intended to reduce the starting load; if current levels and other conditions permit, starting under load is also no problem
It has a load switch that is set to start at 50, and the outlet pressure does not reach the rated value
In any case, the inlet and outlet valves should be fully open; after starting up, adjust the return valve to operate the system under no-load conditions