Patent ID: 9739547
Date: 2017-08-22
CPC Classifications: F23J,F23M,F28G,G01B

Claim:
1. An arrangement comprising: a thermal device selected from the group consisting of: a boiler, a gasification reactor, a pyrolysis reactor, and a torrefaction reactor, having walls which enclose inner parts of the thermal device; an inner surface of the thermal device which has the property of at least one of reflecting and scattering electromagnetic radiation; a laser source for producing an electromagnetic radiation signal directed at the inner surface, the laser source outside the thermal device arranged at a first distance from said surface; a detector of electromagnetic radiation arranged at a second distance from said inner surface and in electromagnetic radiation receiving relation to receive reflected electromagnetic radiation from said inner surface; a window or an aperture configured to transmit an electromagnetic radiation signal from the laser source to said inner surface; an extending pipe positioned so that the electromagnetic radiation signal from the laser source passes through the pipe; a source of protective gas connected to the pipe to supply protective gas to the pipe; a processing unit connected to the detector to determine a distance between said inner surface and the detector to determine a first length, and to periodically compare said first length to a second length produced by repeating the determination of the distance between said inner surface and the detector, to measure a growth in contamination on the inner surface; a cleaning device for cleaning the inner surface of the thermal device; a control device for controlling said cleaning device, connected to the processing unit in data receiving relation to operate the cleaning device when the inner surface has a selected thickness of contamination on the inner surface.