GB798243A - Improvements in or relating to methods for generating steam in forced-flow boilers and to apparatus for regulating such boilers - Google Patents

Abstract

798,243. Automatic control systems for boilers. ZUPPKE, B. Sept. 30, 1955 [Sept. 30, 1954], No. 27973/55. Class 38 (4). In a control system for a forced flow boiler, the fuel supply to the boiler is automatically regulated in dependence on variatinso of water pressure in a water section of the boiler. In Fig. 2, water supplied to a forced-flow boiler through a conduit f passes through an economizer a to a radiation heater b in which it is converted into steam which passes through a supercharger d and a reheater e on its way to a discharge conduit g. Conversion to steam may be completed in a further heater located with the economizer and reheater and connected between the radiation heater b and superheater d. Outlet steam pressure is maintained constant by a pressure detector i controlling a valve h in the discharge conduit. Changes in inlet water pressure at a point P1, consequent upon a change in the relationship between the rate of supply of heat and the rate of supply of feed water are detected by a flow meter Mo, in. a conduit between the inlet and discharge conduits, which controls a rheostat M<SP>1</SP>0 in a bridge circuit, Fig. 2a, to energize a two-way relay r and thereby operate a motor RM in the appropriate direction to alter the supply of coal dust to burners I by adjustment of a speed regulator RK for a motor MK driving a fuel distributer K. Alternatively the pressure in the inlet conduit at P1 may alone control potentiometer M<SP>1</SP>0. To compensate for variations in load on the boiler a flow detector Q in the inlet conduit operates a potentiometer Q<SP>1</SP> to alter the balance point of the bridge circuit. A detector T responsive to the temperature of steam in the discharge conduit adjusts a rheostat T<SP>1</SP> to prevent temperature deviation beyond predetermined limits. Discharge pressure detector i may control the supply of fuel and feed water instead of valve h to maintain constant discharge pressure.