Patent ID: 7831084

Claim:
A method for controlling the operation of a recovery boiler or another boiler having a furnace wherein the operation is monitored by monitoring sensors, the method comprising: said sensors converting the acquired electromagnetic radiation to electrical signals which are conducted to image processing which forms an image of an object, wherein the imaged object includes at least one of a char bed, char, chemicals on at least one of the furnace walls, and deposits on boiler surfaces, and the image is formed based on the data from the sensors; controlling an operation using the image, wherein the operation includes as least one of burning of the char bed, formation of the char, formation of the chemicals on the furnace walls, and formation of the deposits on the boiler surfaces; arranging the sensors to produce sensor signals for 3D (three-dimensional) imaging, prior to converting acquired electromagnetic radiation to electrical signals; wherein the sensor signals are conducted to the image processing unit for forming a 3D image, such as an image of the bed and/or the char and/or the chemicals, and/or its shape describing derivatives, and/or temperature chart of the bed surface, and that the image processing further comprises a filtering phase wherein the sensor signals or the 3D image are/is filtered in order to avoid the thermal radiation emission of hot gases, liquids and/or particles in the furnace, wherein the sensor signals or the 3D image are/is conducted to a filter unit filtering the signals/images to several relatively narrow bands (BAND1 to BANDn), whereby the final 3D image is obtained by comparative analysis of the sensor signals or the 3D images from the chosen different frequency bands.