GB899415A - Apparatus for controlling the flow of heating gases in steam boilers or water heaters - Google Patents

Abstract

899,415. Water tube boilers; regulating superheaters. MARTIN, J. J. Jan. 19, 1961 [Jan. 20, 1960], No. 2199/61. Classes 123(2) and 123(3) The flow of heating gases, conducted consecutively through the flues 1, 2 of a steam. boiler containing heating surfaces and a horizontal pass 3 leading to a final uptake 17 by way of a flue 16 and a parallel by-pass 7, is regulated by the selective operation of valves 4, 8 located respectively at the inlet ends of the flue 16 and the by-pass 7 and at an opening 18 in a wall 14 between the flue 2 and the bypass 7 and of valves 13, 13<SP>1</SP> arranged in the common wall 15 between the flue 16 and the by-pass 7. In order when starting the boiler to prevent corrosion of combustion air heaters 9, 10 and 12 and a feedwater heater 11 in the flue 16 the valve 4 is placed in the closed position f, f, the valve 13 in the position h, and the valve 8 in the fully open position c so that the combustion gases flow through the opening 18 directly to the uptake 17. As the heat of the tubes in the flue 2 increases the valve 8 is moved to close the opening 18, the valves 13, 13<SP>1</SP> are arranged in their closed positions g, g, and the valve 4 is placed in the position e, e so that the gases pass through the by-pass 7 and none through the flue 16. As the temperature of the gases becomes high enough to avoid corrosion of the heat exchange surfaces 9-12 in the flue 16 the valves 13, 13<SP>1</SP> are gradually opened one after the other. When the gas temperature has increased sufficiently the valve 4 is placed in the position d, d the gases from the flue passing through the flue 16, and the temperature of the combustion air and feedwater being regulated by adjustment of the valves 13, 13<SP>1</SP>. At partial load operation, or at low heating value of the fuel burned, the valve 8 may be placed in the position b the valve 4 in position f, f, and the valves 13, 13<SP>1</SP> in position g so that the heating gases by-pass the flue 2, fine adjustment being obtained by moving the valve 4 slightly towards the position e, e. If it is desired to produce a low heating of the heat exchangers 9-12 although the temperature of the combustion gases is high the valve 4 is placed in the position e, e so that the gases are directed through the pass 7, the valves 13, 13<SP>1</SP> being moved toward the position h, on the valve 4 being slightly opened, to obtain the required amount of heating of the heat exchangers 10-12. In a modification the rotary flap valve 4 is replaced by three simple flap valves controlling respectively the outlet and inlet of the flues 2, 16 and the inlet to the by-pass 7. In a further modification, Fig. 3, where the full range of control is not necessary, a valve 4<SP>11</SP> controls the inlet to the by-pass 7 and also an adjacent opening in the wall 14 having another opening higher up which is controlled by a valve 3<SP>1</SP>. The valves, which are balanced, may be remotely controlled by conventional temperature sensitive devices inserted in the flues and passes. The remote control mechanism may be by means of follower cams, pneumatic servo motors interconnected through drum controllers programme controlled.