Method and apparatus for continuously sensing the condition of a gas stream

Abstract

A loop type sample gas flow conduit has an inlet opening that is connected to an opening in the gas main passageway and an outlet opening connected to a second opening in the main gas passageway. The sample gas flow conduit has a gas inlet leg and a gas outlet leg arranged at spaced relation to each other. A heater element surrounds a portion of the gas inlet leg and a suitable temperature control device provides a temperature differential between the gas inlet leg and the gas outlet leg so that a sample stream of gas is withdrawn from the stream of gas in the main passageway by convection and at a preselected flow rate. An electrochemical sensing cell is positioned in the gas inlet leg and continuously determines the oxygen partial pressure of the gas flowing through the sample gas flow conduit.

What is claimed is: 
     
       1. Apparatus for continuously sensing the condition of a gas flowing in a main passageway comprising, a sample gas flow conduit having an inlet opening and an outlet opening connected to spaced openings in the main passageway,   said sample gas flow conduit having a gas inlet leg extending upwardly at an angle to the earth's surface and a gas outlet leg extending downwardly at an angle to the earth's surface, said gas inlet leg and said gas outlet leg arranged in spaced relation to each other and operable to provide a difference in static head therebetween,   means to heat said gas inlet leg and maintain a temperature differential between said gas inlet leg and said gas outlet leg so that a sample stream of gas is withdrawn from said gas flowing in said main passageway by convection and at a preselected flow rate,   said gas inlet leg includes an enlarged portion, and   a ceramic oxide electrolyte electrochemical cell positioned in said enlarged portion of said gas inlet leg of said gas flow conduit to measure the oxygen partial pressure of said stream of gas flowing through said sample gas flow conduit.   
     
     
       2. Apparatus for continuously sensing the condition of a gas flowing in a main passageway as set forth in claim 1 which includes, temperature control means to maintain the temperature of said gas inlet leg at a preselected temperature.   
     
     
       3. A method for continuously sensing the condition of a gas flowing in a main passageway comprising, connecting a gas inlet leg of a sample gas flow conduit to an opening in the main passageway,   connecting a gas outlet leg of said sample gas flow conduit to a second opening in said main passageway,   said gas inlet leg and said gas outlet leg arranged in spaced relation to each other and operable to provide a difference in static head therebetween,   positioning a ceramic oxide electrolyte electrochemical cell in one of said legs of said gas flow conduit, and   heating said gas inlet leg and maintaining a temperature differential between said gas inlet leg and said gas outlet leg so that a sample stream of a gas is withdrawn from said gas flowing in said main passageway by convection at a preselected flow rate and measuring the oxygen partial pressure of said sample stream of gas.   
     
     
       4. A method for continuously sensing the condition of a gas flowing in a main passageway as set forth in claim 3 which includes, maintaining the temperature of said gas inlet leg at between about 1,100° F. to 1,600° F.   
     
     
       5. Apparatus for continuously sensing the condition of a gas flowing in a main passageway comprising, a sample gas flow conduit having an inlet opening and an outlet opening connected to spaced openings in the main passageway,   said sample gas flow conduit having a gas inlet leg extending upwardly at an angle to the earth's surface and a gas outlet leg extending downwardly at an angle to the earth's surface, said gas inlet leg and said gas outlet leg arranged in spaced relation to each other and operable to provide a difference in static head therebetween,   means to maintain a temperature differential between said gas inlet leg and said gas outlet leg so that a sample stream of gas is withdrawn from said gas flowing in said main passageway by convection and at a preselected flow rate, and   a ceramic oxide electrolyte electrochemical cell positioned in one of said legs of said sample gas flow conduit to measure the oxygen partial pressure of said stream of gas flowing through said sample gas flow conduit.