Patent ID: 8155893
Filing Date: 2012-04-10
Classification: G01J,G01N

Abstract:
1. An apparatus comprising: a first sensor producing a first data signal characterizing a carbon dioxide concentration in the gas stream, the first sensor comprising a tunable diode laser absorption spectrometer comprising a laser light source that is scanned over a wavelength range that includes a selected absorption transition for carbon dioxide and a detector that detects an intensity of light reaching the detector after light from the laser light source passes through the gas stream, the first data signal comprising the intensity as a function of wavelength; and a master processor that performs operations comprising: receiving the first data signal and measurements of pressure and temperature in the gas stream, fitting at least one region in the wavelength range outside of the selected absorption transition to a function to obtain a zero-absorption baseline, determining the carbon dioxide concentration based on a line strength at the selected absorption transition corrected by the zero-absorption baseline, inferring a total hydrocarbon concentration in the gas stream based on a database of characteristic natural gas concentrations, and implementing an algorithm that determines an energy content of the gas stream using as inputs at least the measurements of temperature and pressure, the carbon dioxide concentration, and the inferred total hydrocarbon concentration the algorithm.