Improvements in firing steam generators

135,542. Kirke, P. St. G. Oct. 2. 1918. Fuel and air supply and draught, regulating.- In a multitubular steam-generator in which combustion of liquid or gaseous fuel is effected in the tubes and the draught is caused by a fan arranged at the outlet ends of the tubes, the ratio of the full pressure to the gross draught pressure due to the suction and the pressure at which the fuel is supplied is maintained substantially constant. As shown in the Figure, a gas-fired boiler a provided with a burner box c as described in Specification 124,016 at the front end of the tubes b is fitted with two pressure gauges i, k, one for measuring the gas pressure in the box e and the other for measuring the suction created by the fan f. Corresponding indexes are attached to the gauges so that the operator, after adjusting the draught for maximum efficiency, may adjust the gas pressure so that the two gauges give the same reading. To allow for variations in the calorific value of the fuel, one of the gauges is provided with scales indicating different calorific values of the fuel. An instrument for ascertaining the calorific value of the fuel may be used with the apparatus. According to the Provisional Specification, in the case of solid fuel, the rate of supply should vary as the square root of the variation of the draught.