Volume flow or mass flow measurements in synthesis gas (e.g. from wood gasifiers) are not trivial because of fluctuating gas compositions. Synthesis gas is a multi-component gas mixture, which essentially consists of a non-combustible portion of nitrogen / carbon dioxide and a combustible portion of hydrogen / carbon monoxide and small amounts of hydrocarbons. Depending on the material to be gasified and fluctuations in the quality of the material, the gas composition of the resulting gas also fluctuates more or less. Every thermal mass flow meter of the COMBIMASS series is calibrated to a gas composition. If the current gas composition deviates from the calibration status, greater falsification of the measured values may be to be expected. In particular, fluctuating proportions of hydrogen in the gas flow significantly shift the measurement signal.
An acceptable accuracy of the gas quantity measurement can also be achieved if the thermal sensor is combined with a thermal conductivity sensor. With the help of the second sensor in the flow-calmed area, the hydrogen concentration in the gas can be determined, which is read into the electronics of the thermal sensor via a 4-20 mA signal. This then corrects its measured value accordingly. The COMBIMASS® syngas measuring system is therefore a device combination in a wafer-type design.
Before delivery, each system is calibrated in our CAMASS® calibration laboratory, taking into account the real operating conditions with regard to gas composition and installation situation (internal pipe diameter, flow, ...). Approved test sections, standard orifices and precision inclined tube manometers are used as a reference, and calibrated pressure and temperature transmitters also enable the exact determination of the operating conditions and volume flows on site. These measuring devices are regularly checked by external laboratories as part of ISO quality assurance. State-of-the-art computer and simulation programs, which are based on decades of experience, are used to calculate the calibration data and to determine the correction factors for temperature compensation.
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