Method and device for recycling gas

Abstract

A device and method for recycling of gas used during the quenching process in a thermal treatment, for example, in which the gas is removed directly from a quenching chamber and is compressed to the pressure prevailing in the high-pressure container rather than being decompressed into a gas buffer, an additional compression step being connected if the pressure inside the chamber lies below a threshold value, wherefore conduits comprising overflow regulators lead to the individual compression steps.

1 . A method for recovery of gas released from a high-pressure container into a closed chamber, comprising the steps of: 
 compressing gas drawn directly from the closed chamber with at least one high compression stage and returning the compressed gas to the high pressure chamber until gas pressure in the closed chamber falls below an inlet pressure limit value; and    after gas pressure has fallen below the inlet pressure limit value, compressing gas down directly from the closed chamber with at least one low compression stage and feeding the output of the at least one low compression stage into the inlet of the at least one high compression stage for further compression and return to the high pressure chamber.    
   
   
       2 . The method as claimed in  claim 1 , wherein a multistage compressor or multiple compressors connected in series are used.  
   
   
       3 . The method as claimed in  claim 1 , wherein the individual compression stages are supplied with gas directly according to the falling evacuation pressure of the chamber.  
   
   
       4 . The method as claimed in  claim 1 , wherein the gas with the highest compression capacity is compressed in the highest compression stage.  
   
   
       5 . The method as claimed in  claim 1 , wherein the pressure in the chamber is between 6 and 60 bar at the beginning of gas recovery and the pressure in the high-pressure container is between 8 and 62 bar.  
   
   
       6 . The method as claimed in  claim 1 , wherein nitrogen, argon and helium.  
   
   
       7 . A device for recovery of gas released from a high-pressure container into a closed chamber, comprising: 
 at least one high compression compressor stage,    at least one low compression compressor stage,    gas lines directly connecting the closed container with each compression stage without intermediate storage;    isolation devices in each gas line between each compression stage and the closed container, said isolation devices comprising at least one of cut-off valves and over-current regulators; and    a switching unit, said switching unit controlling selective operation of the isolation devices to 
 directly connect a first of the at least one high compression stage inlet to the closed chamber to receive and compress the gas from the closed chamber until gas pressure in the closed chamber falls below an inlet pressure limit value; and  
 after gas pressure in the closed chamber has fallen below the inlet pressure limit value, isolate the at least one high compression stage from direct connection to the closed chamber, connect the at least one low compression stage inlet to the closed chamber, and feed the output of the at least one low compression stage into the inlet of the at least one high compression stage for further compression and return to the high pressure chamber.  
   
   
   
       8 . The device as claimed in  claim 7 , further comprising: 
 a pressure sensor for detecting gas pressure in the closed chamber,    wherein the pressure sensor output is provided to the switching unit for use in determining when to selectively operate the isolation devices.    
   
   
       9 . The device as claimed in  claim 7 , wherein one or more compression stages include multiple compressors conducted in parallel.  
   
   
       10 . The device of  claim 7 , wherein the closed chamber is a heat treatment quenching process chamber.  
   
   
       11 . The method of  claim 1 , wherein the recovery of gas follows release of the gas in a heat treatment quenching process.