Abstract
A novel miniaturized calorimeter-type sensor device with a dual-catalyst structure was fabricated by integrating different catalysts on the hot (Pd/θ-Al2O3) and cold (Pt/α-Al2O3) ends of the device. The device comprises a calorimeter with a thermoelectric gas sensor (calorimetric-TGS), combining catalytic combustion and thermoelectric technologies. Its response for a model fuel gas of hydrogen and methane was investigated with various combustor catalyst compositions. The calorimetric-TGS devices detected H2, CH4, and a mixture of the two with concentrations ranging between 200 and 2000 ppm at temperatures of 100–400 °C, in terms of the calorie content of the gases. It was necessary to reduce the much higher response voltage of the TGS to H2 compared to CH4. We enhanced the H2 combustion on the cold side so that the temperature differences and response voltages to H2 were reduced. The device response to H2 combustion was reduced by 50% by controlling the Pt concentration in the Pt/α-Al2O3 catalyst on the cold side to 3 wt%.
Highlights
Gas calorimeters, which measure the calorific values or Wobbe Index (WI) of gases [1], are used to control the thermal input in various types of steel mill and petrochemical industry furnaces, as well as control the fuel in power plant turbines
This result indicates that the H2 combustion performance of the Pt/α-Al2O3 catalyst improves by increasing the Pt concentration
[(∆V to H2) + (∆V to CH4)]/2 with the experimental data from the response voltages to H2 and CH4
Summary
Gas calorimeters, which measure the calorific values or Wobbe Index (WI) of gases [1], are used to control the thermal input in various types of steel mill and petrochemical industry furnaces, as well as control the fuel in power plant turbines. Sensors 2014, 14 gasification products are highly complex, sophisticated apparatus for monitoring the heats of combustion of fuels in the burners or turbines of power plants [2]. A new sensor device is presented in this study which contains all the functional elements of a conventional thermocouple-type calorimeter (temperature sensor, catalytic combustor, and heater). The device, essentially a calorimeter of a thermoelectric gas sensor (calorimetric-TGS), combines catalytic combustion and thermoelectric technologies [3]. Natural gas consists mostly of methane, along with lesser amounts of ethane and propane Noncombustible components such as carbon dioxide and nitrogen may be present. The fabrication, characterization, and gas responses of the micro calorimetric-TGS devices, which utilize a thermoelectric thin film, were investigated with various catalytic combustor material sets and operating temperatures. The responses of the TGS to the combustion heat for different compositions of gases were investigated
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