US 4,380,400 AGranted

Combustible gas analyzer

AssigneeHoneywell Inc.

InventorJohn L. Searle

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Abstract

A combustible gas analyzer for determining the calorific content of a combustible gas uses a constant flow rate air supply and a constant pressure combustible gas supply to provide oxygen and gas for combustion. The regulated air is supplied directly to be mixed with the combustible gas. On the other hand, the combustible gas is passed through a series connection of a pressure regulator and a variable orifice or valve before mixing with the air supply. A feedback pressure to control the pressure regulator for the gas is obtained from the output of the valve. The mixture of air and gas is burned in a combustion chamber, and a zirconium oxide detector is arranged to measure the oxygen content of the combustion products to enable a predetermined oxygen level to be reached, e.g., stoichiometric combustion. The valve is operated by a valve control apparatus responsive to the output of the detector to maintain the preset oxygen level. The position of the valve is monitored as a representation of the calorific content of the combustible gas.

Claims6

Dependent claims

A combustible gas analyzer comprising

first pressure control means for supplying combustion air at a predetermined flow rate,
second pressure control means for supplying a combustible gas to be analyzed at a controlled flow rate, said second control means having an input, an output and a pressure feedback,
gas mixing means for mixing air from said first pressure control means and a combustible gas to be analyzed,
valve means located at said output of said second control means for performing a valving operation on a flow of a combustible gas to be analyzed from said second control means, said valve means including a valve stem and a valve stem drive motor,
feedback pressure means connected between an output of said valve means and said feedback of said second control means for providing a feedback pressure signal to said second control means to control the pressure of said combustible gas at said output of said second control means,
combustion means connected to an output of said mixing means for producing a combustion of a mixture of said air and said combustible gas from said mixing means,
detector means for detecting the oxygen content of combustion products from the combustion of said air and said combustible gas by said combustion means,
control means responsive to said detector means for producing a control signal for controlling said valving operation of said valve means to achieve a preselected oxygen content of said combustion products,
circuit means for applying said control signal to said valve motor to effect a corresponding motion of said valve stem,
valve stem movement monitoring means connected to said valve stem for producing a signal representative of the position of said valve stem and
display means for displaying said signal from said monitoring means as an indication of the calorific content of said combustible gas.

8 more elements

Dependencies are inferred from the claim text.