Compressor inter-stage temperature control

Abstract

A method, system and apparatus for providing temperature control of compressed gases between stages of a multiple-stage compressor, by selectively manipulating a valve which can cause at least a portion of the compressed gases to flow through an air-cooled heat exchanger.

1 . A method for regulating temperature of a gas between stages of compression comprising:
 providing a control valve between stages of compression;   providing an air-cooled heat exchanger;   monitoring the temperature of the gas in at least one location; and   manipulating the control valve such that at least a portion of compressed gas from a first stage of compression can be selectively caused to flow through the air-cooled heat exchanger before being introduced into a second stage of compression.   
     
     
         2 . The method of  claim 1  wherein the at least one location is downstream of an outlet of the second stage of compression. 
     
     
         3 . The method of  claim 1  wherein the at least one location is between an outlet of the air-cooled heat exchanger and an inlet of the control valve. 
     
     
         4 . The method of  claim 1  wherein manipulating the control valve comprises modulating the control valve. 
     
     
         5 . The method of  claim 1  wherein the control valve comprises a first inlet which is coupled to an outlet of the first stage of compression. 
     
     
         6 . The method of  claim 5  wherein the control valve comprises a second inlet which is coupled to an outlet of the air-cooled heat exchanger. 
     
     
         7 . The method of  claim 6  wherein manipulating the control valve comprises adjusting a flow ratio, the ratio being a formed between a flow rate of gas entering the first inlet of the control valve and a flow rate of gas entering the second inlet of the control valve. 
     
     
         8 . The method of  claim 7  wherein manipulating the control valve further comprises modulating the control valve with a modulating valve. 
     
     
         9 . The method of  claim 8  wherein the modulating valve is controlled in response to a temperature monitored in a second location and wherein the control valve is adjusted in response to a combination of the temperature that is monitored at the first location and a temperature that is monitored at the second location. 
     
     
         10 . The method of  claim 9  wherein the first location comprises a location that is downstream of the second stage of compression and wherein the second location comprises a location between an outlet of the air-cooled heat exchanger and the second inlet of the control valve. 
     
     
         11 . The method of  claim 1  wherein the control valve is manipulated so as to maintain a temperature of the gas after having passed through the second stage of compression within a predetermined temperature range. 
     
     
         12 . The method of  claim 1  wherein the control valve is manipulated so as to maintain a temperature of gas exiting the air-cooled heat exchanger above a predetermined set point. 
     
     
         13 . The method of  claim 1  wherein the second stage of compression comprises a third stage of compression of a multi-stage compressor and wherein the first stage of compression comprises a second stage of compression of the multi-stage compressor. 
     
     
         14 . The method of  claim 1  wherein the control valve comprises an outlet communicably coupled to an inter-stage scrubber. 
     
     
         15 . An apparatus for controlling temperature of gases between stages of compression for a multi-stage compressor comprising:
 a control valve, said control valve comprising first and second inlets and an outlet, said first inlet coupled to an outlet of a first stage of the multi-stage compressor, said second inlet coupled to an outlet of an air-cooled heat exchanger, said outlet of said control valve coupled to an inter-stage scrubber; and   a modulating valve communicably coupled to said control valve; said modulating valve configured to manipulate said control valve based on a temperature of the gases at a location between an outlet of said air-cooled heat exchanger and said second inlet of said control valve.   
     
     
         16 . The apparatus of  claim 15  wherein said control valve is manipulated based on a temperature of the gases at a location that is downstream from a second stage of the multi-stage compressor. 
     
     
         17 . The apparatus of  claim 15  further comprising process control logic connected to said modulating valve. 
     
     
         18 . The apparatus of  claim 15  wherein said control valve adjusts a mixture of gas having passed through said air-cooled heat exchanger with hot gas exiting the first stage of the multi-stage compressor. 
     
     
         19 . The apparatus of  claim 15  wherein said control valve and said air-cooled heat exchanger are positioned such that at least a portion of hot gas from the first stage of compression can be caused to flow through said air-cooled heat exchanger before entering said second inlet of said control valve and at least a portion of hot gas from the first stage of compression of the multi-stage compressor enters said second inlet of said control valve. 
     
     
         20 . The apparatus of  claim 15  wherein each of said components are duplicated and rather than being disposed between the first and second stages of compression of the multi-stage compressor, the duplicated components are instead disposed between second and third stages of the multi-stage compressor.