GB884358A - Steam power plants - Google Patents

Abstract

884,358. Disposal of steam boiler blow-off. SULZER FRERES S.A. Oct. 4, 1960 [Oct. 15, 1959], No. 34037/60. Class 123(2) In a steam power plant where a by-pass pipe 47, branching off between a superheater 2 and a prime mover 3, is fitted with a valve 24 operable in dependence upon the operating condition of the working medium the by-pass valve is influenced by a signal which depends upon the flow of working medium through the superheater 2. In normal operation all of the steam generated in an evaporator 1 and passing through the superheater is fed, through a steam pipe 40 and a valve 12, to a high-pressure turbine section 3 partially expanded steam then flowing through a pipe 42 to an intermediate reheating superheater 4 leading through a valve 13 to a low pressure turbine section 5. The pressure drop across the superheater 2 is sufficient to maintain the piston rod of a piston 20, in a pressure sensing cylinder connected across the superheater 2, withdrawn from one end of a lever 23 the other end of which is connected to a spring balanced spindle 61 maintaining the valve 24 in the by-pass pipe 47 in the closed position. Since there is no pressure drop in throttles 25, 29, situated respectively in the by-pass pipe 47 and in a serially connected bypass pipe 47<SP>1</SP>, a valve 30 controlling the latter is also closed so that no steam by-passes either of the sections 3, 5. If the flow through the superheater is reduced, e.g. by adjustment of the valves 12, 13, the piston 20 is moved to the right, as the result of the reduced pressure drop across the superheater 2, so that its piston rod urges the lever 23 in a direction to open the valve 24 and allow steam to enter the by-pass pipe 47. The steam flow in the by-pass produces a pressure drop at the throttle 25 which is transferred, through pipes 64, 65, to a piston 66 to open the valve 30 a piston valve 26 in the line 64 being opened by the movement of a lever 57 connected to the rod of the piston 20. The lever 57 is connected at its upper end to the rod 59 of a piston 22 which slides in a cylinder having connection with a pressure signal line 21 leading, e.g. to a load controller, not shown. Feedwater or condensate is drawn respectively through Venturi tubes 49, 33 from storage and condensate tanks 72, 34 the tank 34 being supplied with water through a pipe 52 having a valve 53 which is influenced by a regulator 54 in dependence upon the water level in the tank 34. Added steam in the by-pass 47<SP>1</SP> due to independent operation of the valve 13 is sensed by the throttle 29 which, through a piston and cylinder unit 27, 68, further adjusts the valve 30.