Photometric device and photometric method for determining the gross calorific value of a test gas

Photometric device for determining the gross calorific value of a test gas having:

• a radiation source (1) that generates a measuring beam (2);
• a spectral unit (4, 14, 16, 22) for dividing the measuring beam (2) spectrally into a plurality of adjacent partial spectral regions of a spectral region having several absorption bands comprising absorption lines;
• a test cell (3) for containing the test gas arranged in the path of said measuring beam;
• a radiation receiver (6, 7), for generating electric measuring signals in dependence on the measuring beam intensity in their respective partial spectral region, and is arranged in the path of said measuring beam, wherein the measuring signals relate to the partial spectral regions of the spectral region having several absorption bands;
• and
• an evaluation unit electronically connected to the radiation receiver and equipped with at least one signal amplifier (9, 34) for amplification of the measuring signals,
• wherein based upon a composition of the test gas with regard to the components or functional groups of the test gas and positions of the absorption bands and the absorption lines, the radiation receiver records independent partial spectral regions of a said absorption band and/or a said spectral region comprising the absorption lines creating one of said measurement signals with respect to each partial spectral region,
• wherein the or every signal amplifier (9, 34) that is allocated to the partial spectral region amplifies the measuring signal coming from this partial spectral region with a degree of amplification that is allocated to this partial spectral region, and
• wherein the evaluation unit comprises a summer (10, 34) for summing up the amplified measuring signals.