Device for circulating sealing gas for mechanical dry seals of a centrifugal compressor at times when the machine is stationary and pressurized

1. A device for circulating sealing gas for mechanical dry seals of a centrifugal compressor at times when the compressor is stationary and pressurized, comprising: a sealed reciprocating compressor, the reciprocating compressor including a piston slidable in a cylinder, said piston being movable by a magnetic coupling between said piston and an external magnetic element and movable along said cylinder to move gas from the reciprocating compressor to the dry seals and a heater for receiving the gas moved by said reciprocating compressor and raising the temperature of the gas to a sufficient temperature to prevent the formation of condensate and/or ice between a sealing ring and disc of said mechanical dry seals.

2. Gas circulation device according to claim 1 , wherein said external magnetic element is moved by a reciprocating motor.

3. Gas circulation device according to claim 2 , wherein said reciprocating motor is of the pneumatic type.

4. Gas circulation device according to claim 1 , wherein said external magnetic element is a ring which is moved outside the said cylinder.

5. Gas circulation device according to claim 1 , wherein said cylinder is made from nonmagnetic material.

6. Gas circulation device according to claim 1 , wherein said piston is made from a material sensitive to a magnetic field.

7. Gas circulation device according to claim 6 , wherein said piston is made from a metallic material.

8. Gas circulation device according to claim 1 , wherein said reciprocating compressor is double-acting.

9. Gas circulation device according to claim 1 , wherein dimensions of said reciprocating compressor are small.