On board inert gas generation system with rotary positive displacement compressor

Abstract

An on board inert gas generation system for use in an aircraft having a source of low pressure air includes a variable speed rotary positive displacement compressor with an inlet that receives a first portion of the low pressure air and an outlet in flow communication with an air separation module; a turbine that receives a second portion of the low pressure air to extract energy to drive the compressor; a heat exchanger in a flow path between the compressor and the air separation module, the heat exchanger including a heating pass and a cooling pass, such that compressed air from the compressor is passed along the cooling pass to reduce a temperature of the compressed air supplied to the air separation module; and a duct for supplying cool ram air to the heating pass of the heat exchanger. The compressor provides variable air flow to the air separation module.

What is claimed is: 
     
         1 . An on board inert gas generation system for use in an aircraft having a source of low pressure air, the inert gas generation system comprising:
 a variable speed rotary positive displacement compressor including an inlet configured to receive a first portion of the low pressure air and an outlet in flow communication with an air separation module;   a turbine configured to receive a second portion of the low pressure air and to extract therefrom at least a proportion of the energy required for driving the compressor;   a heat exchanger disposed in a flow path between the compressor and the air separation module, wherein the heat exchanger includes a heating pass and a cooling pass, wherein compressed air from the compressor is passed along the cooling pass to reduce a temperature of the compressed air supplied to the air separation module; and   a first duct configured to supply cool ram air to the heating pass of the heat exchanger,   wherein the compressor is configured to provide variable air flow to the air separation module.   
     
     
         2 . The on board inert gas generation system of  claim 1 , wherein the turbine comprises an output shaft and the compressor comprises an input shaft. 
     
     
         3 . The on board inert gas generation system of  claim 2 , wherein the output shaft of the turbine is drivably connected to the input shaft of the compressor. 
     
     
         4 . The on board inert gas generation system of  claim 2 , wherein the output shaft of the turbine is drivably connected to the input shaft of the compressor via at least one of a gearbox or a motor. 
     
     
         5 . The on board inert gas generation system of  claim 2 , further comprising a generator drivably connected to the output shaft of the turbine and a motor drivably connected to the input shaft of the compressor. 
     
     
         6 . The on board inert gas generation system of  claim 5 , further comprising a controller configured to receive electrical power from the generator and to supply electrical power to the motor to drive the compressor. 
     
     
         7 . The on board inert gas generation system of  claim 6 , wherein the controller is further configured to receive electrical power from a power supply of the aircraft. 
     
     
         8 . The on board inert gas generation system of  claim 7 , wherein the controller is configured to combine and condition the electrical power received from the generator with the electrical power received from the power supply of the aircraft to control the speed of the compressor. 
     
     
         9 . The on board inert gas generation system of  claim 1 , further comprising a second duct configured to vent ram air from the heating pass of the heat exchanger outside of the aircraft. 
     
     
         10 . A method of operating an on board inert gas generation system in an aircraft having a source of low pressure air, the method comprising:
 supplying a first portion of low pressure air to a heating pass of a heat exchanger;   supplying, to a turbine, the first portion of low pressure air from the heating pass of the heat exchanger,   supplying, to a variable speed rotary positive displacement compressor, energy extracted by the turbine from the first portion of low pressure air,   supplying a second portion of the low pressure air to the compressor;   supplying compressed air from the compressor to a cooling pass of the heat exchanger; and   supplying the compressed air from the cooling pass of the heat exchanger to an air separation module,   wherein the compressor is configured to provide variable flow to the air separation module.   
     
     
         11 . The method of operating an on board inert gas generation system of  claim 10 , further comprising supplying cool ram air to the heating pass of the heat exchanger. 
     
     
         12 . The method of operating an on board inert gas generation system of  claim 11 , further comprising selectively supplying to the heating pass of the heat exchanger either the first portion of low pressure air or the cool ram air. 
     
     
         13 . The method of operating an on board inert gas generation system of  claim 12 , further comprising operating a valve to selectively supply to the heating pass of the heat exchanger either the first portion of low pressure air or the cool ram air.