Differential pressure valve with parallel biasing springs and method for reducing spring surge

A poppet valve comprising:

• a valve body, the valve body comprising at least one flow inlet and one flow outlet;
• at least one shutter guide disposed inside the valve body;
• at least one poppet shutter slidingly guided by the shutter guide;
• at least one flow passage from the flow inlet to the flow outlet, the flow passage being formed between an inside surface of the valve body and an outside surface of the shutter guide and of the poppet shutter;
• and
• at least one biasing member configured to bias the poppet shutter towards a closed position so as to block the flow passage through the flow inlet;
• wherein the biasing member comprises at least two springs arranged in parallel, one of the springs comprising at least one resonance frequency different from at least one resonance frequency of the other of the two springs, wherein both the two springs are non-linear and wherein the non-linear springs are progressive springs.

A reciprocating compressor comprising:

• a cylinder;
• a piston slidingly arranged and reciprocatingly moving in the cylinder;
• a suction duct and a discharge duct in fluid communication with the cylinder;
• at least a suction valve in the suction duct and a discharge valve in the discharge duct, opening and closing of the suction valve and the discharge valve being automatically controlled by a differential pressure across the valves, wherein the suction valve and the discharge valve are poppet valves comprising:
• a valve body, the valve body comprising at least one flow inlet and one flow outlet;
• at least one shutter, the shutter being movable between an open position and a closed position under a differential pressure across the valve;
• a flow passage from the flow inlet to the flow outlet;
• and
• at least one biasing member configured to bias the shutter towards the closed position so as to block the flow passage through the flow inlet,
• wherein the biasing member comprises at least two springs arranged in parallel, one of the springs comprising at least one resonance frequency different from at least one resonance frequency of the other of the two springs, wherein the two springs are non-linear and wherein the non-linear springs are progressive springs.

A method for mitigating or suppressing spring surge in a differential pressure valve, the method comprising:

• providing the differential pressure valve, wherein the differential pressure valve is a poppet valve comprising:
• a valve body, the valve body comprising at least one flow inlet and one flow outlet;
• at least one shutter, the shutter being movable between an open position and a closed position under a differential pressure across the valve;
• at least one flow passage from the flow inlet to the flow outlet;
• at least one biasing member configured to bias the shutter towards the closed position so as to block the flow passage through the flow inlet;
• and
• suppressing propagation of resonance compression waves in the biasing member by providing in the biasing member at least two springs in parallel, one of the springs comprising at least one resonance frequency different from at least one resonance frequency of the other of the two springs, wherein both the two springs are non-linear and wherein the non-linear springs are progressive springs.

A method for operating a reciprocating compressor, the compressor comprising:

• a cylinder;
• a piston sliding in said cylinder;
• a suction duct with a suction valve and a discharge duct with a discharge valve, each valve comprising at least one shutter, at least one biasing member configured to bias the shutter towards a closed position, the method comprising:
• providing for each biasing member at least two springs in parallel, one of the springs comprising at least one resonance frequency different from at least one resonance frequency of the other of the two springs, wherein both the two springs are non-linear and wherein the non-linear spring are progressive springs;
• reciprocatingly moving the piston in the cylinder to suck a gas in the cylinder at a suction pressure and discharge the gas from the cylinder at a discharge pressure;
• selectively opening and closing the suction valve and the discharge valve by differential pressure across the valves;
• and the valve is a poppet valve.