Convection section ash monitoring

Claim 1

In a steam generating apparatus comprising a combustion section wherein fuel is burned in an air stream to generate heat and to produce a hot combustion products gas stream, a convection section connected to said combustion section by conveying passage means to permit the flow of said hot combustion products gas stream from said combustion section to said convection section, and heat exchange tubes located in said convection section transverse to the intended direction of gas flow through said convection section so as to contact the hot combustion products gas stream and having steam of temperature lower than that of the hot combustion products gas stream passing therethrough, said heat exchange tubes being arranged in a plurality of banks of said heat exchange tubes, the improvement which comprises: a temperature detection means provided upstream of each bank of heat exchange tubes and downstream of the last bank to determine the fall in temperature across each bank, each of said temperature detection means being capable of directly measuring the temperature of said hot combustion products gas stream at the locations of said temperature detection means; means for on-line calculation of a fouling factor (R F ) for each said bank of heat exchange tubes from the difference in temperature thereacross determined by said temperature detection means; and means for activating soot blowers to effect cleaning of a selected bank of heat exchange tubes in response to a predetermined value of said fouling factor for said selected bank.