Natural gas depressurization system with efficient power enhancement and integrated fail safe safety device

Abstract

The instant invention provides a gas depressurization station, comprising a preheater for preheating a gas, an expander having an output shaft for expanding and depressurizing the gas, and an air compressor coupled to the output shaft for creating high pressure air for use in controlling the depressurization process. The invention is also directed to a method for safely depressurizing a gas, comprising: passing the gas through a preheater and a gas expander which drives an output shaft; driving an air compressor attached to said output shaft to produce compressed air; and controlling the pressure of said compressed air by means of control throttling means; whereby unwanted variations in the speed of rotation of said output shaft may be safely controlled by said control throttling means.

What is claimed is:  
     
         1 . A gas depressurization station, comprising a preheater for preheating a gas, an expander having an output shaft for expanding and depressurizing the gas, and an air compressor coupled to the output shaft for creating high pressure air for use in controlling the depressurization process.  
     
     
         2 . The gas depressurization station of  claim 1 , wherein some of the air output from said air compressor is used to preheat the gas in said preheater.  
     
     
         3 . The gas depressurization station of  claim 1 , wherein some of the air output from said air compressor is used to generate power.  
     
     
         4 . A gas depressurization station, comprising a preheater for preheating a gas, an expander having an output shaft for expanding and depressurizing the gas, and a fail-safe safety system comprising: an air compressor coupled to the expander output shaft; and control throttle means to throttle the air output from said air compressor; whereby unwanted variations in the rotation speed of said shaft may be controlled by said control throttle means.  
     
     
         5 . The gas depressurization station of  claim 4 , wherein said control throttle means comprises a pressure reduction valve and a fail safe main air pathway shutoff valve connected in parallel to the output of said air compressor.  
     
     
         6 . The gas depressurization station of  claim 4 , wherein some of the air output from said air compressor is used to preheat the gas in said preheater.  
     
     
         7 . The gas depressurization station of  claim 4 , wherein some of the air output from said air compressor is used to generate power.  
     
     
         8 . A method for safely depressurizing a gas, comprising: passing the gas through a preheater and a gas expander which drives an output shaft; driving an air compressor attached to said output shaft to produce compressed air; and controlling the pressure of said compressed air by means of control throttling means; whereby unwanted variations in the speed of rotation of said output shaft may be safely controlled by said control throttling means.  
     
     
         9 . The method of  claim 8  for safely depressurizing a gas, wherein some of the compressed air produced by said air compressor is used to preheat the gas in said preheater.  
     
     
         10 . The method of  claim 8  for safely depressurizing a gas, wherein some of the compressed air produced by said air compressor used to generate power.