GB611659A - Improvements in or relating to heating plant - Google Patents

Abstract

611,659. Heating by circulation of fluids. BABCOCK & WILCOX, Ltd., and LULY, E. L. May 3, 1946, No. 13470. [Class 64(ii)] In a heating plant, liquid from a forced circulation boiler 1 passes through heat utilizing means 13, e.g., radiators, and the liquid temperatures at the inlets of the boiler and the heat utilizing means are separately regulable. The temperature of the liquid supplied to the heat utilizing means is maintained below the temperature of liquid entering the boiler, so that the latter temperature can be kept above the dew-point of the heating gases, to prevent corrosion of the boiler heating surfaces. In the form shown, two constant-speed, constant-volume pumps 11, 12 circulate hot water from the water tube boiler 1 to the heat utilizing means 13 and back again, one pump 11 being in a local circuit, formed by a by-pass 18, with the heat utilizing means 13 and the other 12 in a local circuit, formed by a by-pass 19, with the boiler 1. The local circuit of pump 11 uses water generally cooler than that elsewhere in the system but is kept up to necessary temperature by water from the outlet header 6 of the boiler, a thermostat 23 in this circuit controlling the motor of the chain grate stoker 7 and also therefore the boiler rate of firing and the temperature of the water leaving the boiler. The temperature of the water entering the boiler is regulated by mixing hot water from the by-pass 19 in regulable proportions with the cold water returned from the heat utilizing means 13, in a mixing valve 21 controlled by a thermostat 22 in the inlet pipe to the boiler. In an alternative form the thermostat 22 controls the stoker motor and the thermostat 23 controls a valve in the by-pass 18, the mixing valve 21 being dispensed with. A saturation temperature warning device 40 and a make-up water tank 41 are provided.