Abstract: A method for measuring, from a thermal device, temperature, molecular number density, and/or pressure of a gaseous compound as function of distance, the gaseous compound absorbing at least some light. The method comprises generating, for a first wavelength band and a second wavelength band, a pulse sequence comprising a light pulse or light pulses, guiding the pulse sequence into the thermal device, and measuring, as function of time, the intensity of the scattered light at the first wavelength band and at the second wavelength band. The method further comprises determining information indicative of the differential absorption between the two wavelengths bands using measured intensities and determining the temperature, the molecular number density, and/or the pressure of the gaseous compound using the information indicative of the differential absorption between the two wavelengths bands. A thermal system arranged to carry out the method.

Abstract: The method includes guiding a light beam to a first optical path, the light beam being attenuated to an attenuated light beam and detecting a first value indicative of a first intensity of the attenuated light beam. The method further includes generating a last light pulse, dissociating at least part of the gas compound molecules (optionally excited) or dissociated parts thereof (optionally excited) on the first optical path to first part atoms, molecules, ions, or radicals, and to another part using the last light pulse, the light beam being further attenuated by absorption to the first part atoms, molecules, ions, or radicals on the first optical path. The method further includes detecting a second value indicative of a second intensity of the attenuated light beam and determining, using the first and second values, the gas compound content of the gas mixture. A gas compound measuring device measures uses the method.

Abstract: A method for measuring, from a thermal device, temperature, molecular number density, and/or pressure of a gaseous compound as function of distance, the gaseous compound absorbing at least some light. The method comprises generating, for a first wavelength band and a second wavelength band, a pulse sequence comprising a light pulse or light pulses, guiding the pulse sequence into the thermal device, and measuring, as function of time, the intensity of the scattered light at the first wavelength band and at the second wavelength band. The method further comprises determining information indicative of the differential absorption between the two wavelengths bands using measured intensities and determining the temperature, the molecular number density, and/or the pressure of the gaseous compound using the information indicative of the differential absorption between the two wavelengths bands. A thermal system arranged to carry out the method.

Abstract: The method includes guiding a light beam to a first optical path, the light beam being attenuated to an attenuated light beam and detecting a first value indicative of a first intensity of the attenuated light beam. The method further includes generating a last light pulse, dissociating at least part of the gas compound molecules (optionally excited) or dissociated parts thereof (optionally excited) on the first optical path to first part atoms, molecules, ions, or radicals, and to another part using the last light pulse, the light beam being further attenuated by absorption to the first part atoms, molecules, ions, or radicals on the first optical path. The method further includes detecting a second value indicative of a second intensity of the attenuated light beam and determining, using the first and second values, the gas compound content of the gas mixture. A gas compound measuring device measures uses the method.

Abstract: The composition of flue gas generated in a thermal process, especially in the combustion of bio fuel or refuse-derived fuel, is monitored by measuring the quantity of particles belonging to certain size categories in at least one point along the flow path of the flue gas. Such particle size categories are chosen as objects of the measurement, in which the particles are known to consist mainly of alkali chlorides.

Abstract: A supply and a method for preventing corrosion on heat exchange surfaces of a boiler. Additional material is fed to flue gases of a boiler by at least one supply for additional material. The supply includes a cooled case beam that is hollow inside and several nozzles for feeding the additional material.