Combustor Control

Abstract

An apparatus and method for controlling a combustor on a vapor recovery process system which prevents excessive oxygen from entering a natural transmission line and which prevents the need to vent natural gas to the atmosphere.

1 . A method for controlling a combustor on a vapor recovery process system comprising:
 allowing hydrocarbon vapors to flow from a tank to a control valve;   sensing an oxygen level within the hydrocarbon vapors via an oxygen sensor;   opening the control valve when an oxygen level sensed by the oxygen sensor reaches a predetermined level;   flowing the hydrocarbon vapors to a combustor; and   igniting the hydrocarbon vapors in the combustor.   
   
   
       2 . The method of  claim 1  wherein the hydrocarbon vapors flow to the combustor for a predetermined duration of time. 
   
   
       3 . The method of  claim 2  comprising a user selecting the predetermined duration of time. 
   
   
       4 . The method of  claim 1  wherein the hydrocarbon vapors flow to the combustor until a predetermined oxygen level is achieved. 
   
   
       5 . The method of  claim 1  wherein the oxygen sensor is disposed upstream from a natural gas compressor. 
   
   
       6 . The method of  claim 5  wherein the oxygen sensor is disposed within the tank. 
   
   
       7 . The method of  claim 5  wherein the oxygen sensor is disposed such that it measures combined vapors from a low-pressure separator and the tank. 
   
   
       8 . The method of  claim 1  further comprising monitoring a pressure of the tank. 
   
   
       9 . The method of  claim 1  comprising maintaining a pressure within the tank of at least 3 ounces per square inch. 
   
   
       10 . The method of  claim 1  wherein a natural gas compressor is activated when a pressure of the tank is greater than a predetermined level and an oxygen level sensed by the oxygen sensor is below a predetermined level. 
   
   
       11 . The method of  claim 1  wherein the compressor is activated when a pressure of the tank is greater than 3 ounces per square inch and an oxygen level sensed by the oxygen sensor is below a predetermined level. 
   
   
       12 . A method for preventing excessive oxygen from entering a natural gas transmission line comprising:
 operating a vapor recovery process system by compressing vapors from hydrocarbons with a compressor in the natural gas compressor for transmission in a natural gas transmission line;   communicably connecting a combustor to a control valve;   activating the control valve when the compressor stops such that hydrocarbons flow to the combustor; and   deactivating the control valve.   
   
   
       13 . The method of  claim 12  wherein the control valve is deactivated based at least partially on an output of an oxygen sensor upstream of the compressor. 
   
   
       14 . The method of  claim 12  wherein the control valve is deactivated based at least partially on a tank pressure of a tank upstream of the compressor. 
   
   
       15 . The method of  claim 12  wherein the compressor is deactivated based at least partially upon an output of an oxygen sensor upstream of the compressor. 
   
   
       16 . The method of  claim 12  wherein the compressor is deactivated based at least partially on a tank pressure of a tank upstream of the compressor. 
   
   
       17 . The method of  claim 12  wherein the hydrocarbons selectively flow to either the combustor or the compressor. 
   
   
       18 . The method of  claim 12  wherein the compressor or the combustor are operated so as to maintain a tank pressure of a tank upstream of the compressor of at least 3 ounces per square inch. 
   
   
       19 . The method of  claim 18  wherein the compressor or the combustor are operated so as to maintain the tank pressure at a pressure of at least 5 ounces per square inch. 
   
   
       20 . The method of  claim 12  wherein the compressor and the combustor are operated so as to maintain a tank pressure of a tank upstream of the compressor of at least 3 ounces per square inch. 
   
   
       21 . The method of  claim 12  further comprising igniting the hydrocarbons in the combustor. 
   
   
       22 . A vapor recovery process apparatus comprising:
 a hydrocarbon containment tank;   a compressor;   an oxygen sensor positioned upstream of said compressor; and   a hydrocarbon combustion chamber, said chamber burning hydrocarbons based at least in part on a reading from said oxygen sensor.   
   
   
       23 . The apparatus of  claim 22  wherein said combustion chamber burns hydrocarbons based at least in part on a pressure of said tank. 
   
   
       24 . The apparatus of  claim 22  wherein said compressor operates at least partially on a reading from said oxygen sensor. 
   
   
       25 . The apparatus of  claim 22  further comprising a valve which is operated at least in part based on a reading from said oxygen sensor. 
   
   
       26 . The apparatus of  claim 25  wherein hydrocarbon vapors flow to said compressor when said valve is in a first position and wherein the hydrocarbon vapors flow to said combustion chamber when said valve is in a second position. 
   
   
       27 . The apparatus of  claim 22  wherein said compressor is operated to maintain a pressure of at least 3 ounces per square inch in said tank. 
   
   
       28 . The apparatus of  claim 22  wherein said combustion chamber is operated to maintain a pressure of at least 3 ounces per square inch in said tank.