GB457111A - Improvements in or relating to means for indicating or recording the heat loss or thermal efficiency of industrial furnaces and power plants - Google Patents

Abstract

457,111. Electric signalling systems. ELLIOTT BROS. (LONDON), Ltd., Century Works, Lewisham, London, REBER, J. W., 136, Victoria Street, Westminster, and SMITH, L. W., Century Works, Lewisham, London. May 20, 1935, No. 14749. [Class 40 (i)] [See also Group XX] The responses of a CO2 indicator and a temperature meter for the waste gases of a furnace are combined to give an indication or record of the heat loss in or thermal efficiency of the furnace. The CO2 indicator is of the type in which the electrical resistance of a heated conductor placed in the flue gases is varied in accordance with the thermal conductivity of the gases. The Figure shows an electrically operated arrangement in which a Wheatstone bridge a forms part of an electrical CO2 measuring device, e.g. of the kind described in Specification 212,852, [Class 1 (i)], the proportion of CO2 being inversely as the volume of the waste gases for a given fuel. One diagonal of the bridge a is connected to one coil b of a cross coil instrument. The other coil h is in the diagonal of a Wheatstone bridge having arms comprising fixed resistances g, f, and resistance thermometers e, d, in the flue gases and in the air supply to the burners of the furnace respectively. In a modification, the coil h is in circuit with two thermocouples and the current through it may be adjusted by adding the constant potential drop across a small resistance to the differential e.m.f. from the thermocouples. A pointer j carried by the coils b, h, moves over a scale graduated to indicate either the ratio of the heat lost via the chimney gases to the heat supplied to the furnace or the thermal efficiency.