Method for operating a gas analyzing system and apparatus utilizing the same

摘要

A method and apparatus for a gas analyzing system uses a rotary valve for mixing fuel gas to be analyzed for calorific content and air. The speed of the rotary valve which determines the air-fuel ratio is controlled by a controller sensing combustion products resulting from a combustion of the fuel gas and air mixture. The control of the air-fuel ratio is arranged to produce a substantially stoichiometric combustion at which condition the calorific content of the fuel gas is determined from the controller operation. The air supplied to the rotary valve is initially pumped through a dehumidifier for removing water vapor to minimize the error in the measurement of the calorific content of the fuel gas produced by the entrained water vapor. The dehumidifier includes a labyrinth in the air flow path which is cooled by a thermoelectric cooler below the dew point temperature of the air stream but above the freezing point of water to produce a condensation of the entrained water vapor on the cooled surface. The condensed water is allowed to drain from the dehumidifier by a drain within the cooled environment while the dehumidified air is subsequently applied through a pressure regulator to the rotary mixing valve.