Gas compressor and method for controlling flow rate thereof

Abstract

Provided is a gas compressor with a variable diffuser system capable of suppressing stall and surge. The gas compressor includes i) an impeller fixed to a rotation shaft and having a plurality of blades each including a wing surface and an edge surface on an outer circumferential surface thereof; ii) a shroud surrounding the wing surface; iii) a ring valve installed on a diffuser passage connected with an outlet of the impeller and moving in a direction parallel to the rotation shaft to open and close the diffuser passage; iv) a plurality of veins installed in a circumferential direction of the diffuser passage outside the ring valve in the diffuser passage; and v) an actuator coupled with the ring valve and the plurality of veins to sequentially control movement of the ring valve and rotational angles of the veins.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to and the benefit of Korean Patent Application Nos. 10-2009-0019013 and 10-2009-0019011 filed in the Korean Intellectual Property Office on Mar. 5, 2009 and Mar. 5, 2009, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002](a) Field of the Invention[0003]The present invention relates to a gas compressor, and more particularly, to a variable diffuser system installed on a diffuser passage connected with an impeller outlet to prevent stall and surge, and a method for controlling a flow rate of the gas compressor using the same.[0004](b) Description of the Related Art[0005]In general, a gas compressor accelerates and compresses gas with a centrifugal compression force of an impeller by passing the gas through the impeller that is rotating. A diffuser passage is connected with an impeller outlet to convert kinetic energy into pressure energy of gas by decelerating...

AI Technical Summary

Benefits of technology

[0010]The present invention has been made in an effort to provide a gas compressor and a method for controlling a flow rate of the gas compressor that can effectively prevent stall and surge by preventing gas from flowing backwards by modifying a variable diffuser system.

[0011]Further, the present invention has been made in an effort to provide a gas compressor and a method for controlling a flow rate of the gas compressor that can extend a maximum flow rate range which can be controlled by modifying a variable diffuser system.

[0032]Yet another exemplary embodiment of the present invention provides a method for controlling a flow rate of a gas compressor, including; i) sealing a diffuser passage by closing a ring valve in initial operation and reducing an area of the diffuser passage outside the ring valve by closing a plurality of veins; ii) opening the diffuser passage by opening the ring valve for rated operation; and iii) increasing the area of the diffuser passage outside the ring valve by opening the plurality of veins.

Problems solved by technology

Therefore, a counter current is generated in the diffuser passage, and as a result, stall and surge phenomena appear.

Moreover, when the flow rate of gas is further reduced or the pressures at the inlet and the outlet of the impeller are the same as each other, a surge mode in which a complete counter current is periodically generated in the diffuser passage starts to thereby significantly deteriorate compressor efficiency.

However, the impeller outlet cannot be fully sealed with the variable diffuser in the related art and gas flows backwards through a space between the impeller and the variable diffuser.

Therefore, there is a limit in preventing the stall and the surge.

Further, the variable diffuser in the related art is limited in a flow rate control range and a maximum flow rate range which can be controlled with the variable diffuser in the related art is approximately 45% of a rated flow rate.

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