Multi-stage gas compressing apparatus

Abstract

A multi-stage gas compressing apparatus comprises a primary gas compressor and a secondary gas compressor. A gas compressed in the primary gas compressor is transferred to the secondary gas compressor in which the gas is further compressed. A detector detects upper and lower limits of discharge pressure from the secondary gas compressor, and a signal is sent from the detector to a control device connected to the primary and secondary gas compressors. Then, the primary and secondary gas compressors are started or stopped by the control device.

1 . A multi-stage gas compressing apparatus comprising:
 a primary gas compressor compressing a gas;   a secondary gas compressor connected to the primary gas compressor via a conduit and further compressing the gas compressed by the primary gas compressor;   a storage tank connected to the secondary gas compressor and storing gas further compressed in the secondary gas compressor;   a detector connected to the storage tank and detecting a first upper limit pressure or a first lower limit pressure of the gas in the storage tank to generate a signal; and   a control device connected to the detector, the primary gas compressor and the secondary gas compressor, the signal from the detector being transmitted to the control device to start and stop the primary gas compressor and the secondary gas compressor at the same time.   
   
   
       2 . A multi-stage gas compressing apparatus of  claim 1  wherein the detector comprises a first pressure sensor. 
   
   
       3 . A multi-stage gas compressing apparatus of  claim 1 , further comprising a relief valve at the conduit between the primary gas compressor and the secondary gas compressor, compressed gas being released through said relief valve if discharge pressure from the primary gas compressor exceeds a second upper limit pressure lower than the first lower limit pressure when the secondary gas compressor does not work. 
   
   
       4 . A multi-stage gas compressing apparatus of  claim 1 , further comprising an intermediate control device at the conduit between the primary gas compressor and the secondary gas compressor, the intermediate control device comprising a second pressure sensor and a microcomputer circuit, the primary gas compressor being stopped by the microcomputer circuit if the second pressure sensor detects a second upper limit pressure of gas flowing through the conduit when the secondary gas compressor does not work, the second upper limit pressure lower than the first lower limit pressure. 
   
   
       5 . A multi-stage gas compressing apparatus of  claim 1 , further comprising an intermediate control device at the conduit between the primary gas compressor and the secondary gas compressor, the intermediate control device comprising a second pressure sensor and a microcomputer circuit, the secondary gas compressor being stopped by the microcomputer circuit if the second pressure sensor detects a pressure less than a second lower limit pressure of gas flowing through the conduit when the primary gas compressor does not work, the second lower limit pressure being lower than the first lower limit pressure.