Siemens Aktiengesellschaft

Hermann Dorr

Joachim Franke

Axel Butterlin

A forced once-through steam generator with an evaporator heating surface has a control device for a furnace which is controlled by a setpoint value L assigned to the steam generator power and a control device for a feed-water mass flow M into the evaporator heating surface. In order to avoid an overshoot of a specific enthalpy at an outlet of the evaporator heating surface, a device is superimposed on the feedwater control device which serves to derive a variable Q(L1)/,[h.sub.sA (L2)-h.sub.iE) as a setpoint value M.sub.s for the feed-water mass flow. In this case h.sub.iE is the specific enthalpy at an inlet of the evaporator heating surface, Q(L1) is a value derived by a first power value L1 from a function generator for a heat flow into the evaporator heating surface and h.sub.sA (L2) is a setpoint value derived by a second power value L2 from the function generator for the specific enthalpy at the outlet of the evaporator heating surface. L1 is a first power value which is delayed with respect to the setpoint value L assigned to the steam generator power, and L2 is a second power value which is delayed with respect to the first power value L1.

Forced once-through steam generator

A reducing station has a safety function in a negative direction of action for metering energy flows in the form of gases, steam or water, in particular in thermal or industrial power plants. An operating leg of a servo valve is supplemented by at least one further safety leg of displacing a first spindle section carrying a restrictor body at one end, into a closed position. The displacement is effected as a function of an applied pressure-monitor tripping signal. A second spindle section is coupled to the other end of the first spindle section through preloadable springs and non-self-locking, securely brakeable safety-spindle thread stages. The second spindle section has a spindle drive which transmits an axial thrust or pull to the first spindle section through the securely braked safety-spindle thread stages, in a regulating mode. In a tripping mode, the second spindle section forms an abutment for the movement of the first spindle section with the restrictor body into a desired, closed position. The movement is released by the safety spindles. At least two safety legs each have one non-self-locking safety-spindle drive. Both safety legs can act on a rocker-like, two-armed safety lever. The safety legs can be tested as to their function.

Reducing station having a safety function in a negative direction of

Safety and regulating valves of safety stations meter energy flows in the form of gases, steam or water, in particular in thermal or industrial power plants. In a servo drive for the valves, a drive force for a safety movement of a restrictor body is derived from a working-medium pressure difference acting on the restrictor body. To this end, the spindle drive of the safety valve is constructed in such a way as to be non-self-locking. A rapid-travel mechanism is used instead of a rapid-travel motor. The rapid-travel mechanism is coupled through a non-self-locking gear unit to a planetary gear stage of the servo drive and has a shaft being normally securely braked by a releasable brake device. When the response pressure occurs, the brake device releases the rapid-travel mechanism to perform the safety movement of the restrictor body into its required position by means of the inherent medium. In a positive direction of action, the required position is the open position of the restrictor body, and in a negative direction of action the required position is the closed position.

Servo drive for safety and regulating valves

A control valve assembly having spindle actuation for media in vapor or liquid form includes a main valve having a main valve seat. A control valve has a main throttle body cooperating with the main valve seat for opening and closing the main valve. The control valve has an associated main spindle for transmitting thrust forces to the main throttle body. An auxiliary valve has an auxiliary valve seat. The control valve has an auxiliary throttle body cooperating with the auxiliary valve seat for opening and closing the auxiliary valve. The control valve has an associated auxiliary spindle for transmitting the thrust forces to the auxiliary throttle body. A common spindle actuator supplies control forces for the main spindle and the auxiliary spindle. First and second spring-elastic couplings respectively transmit the control forces to the main and auxiliary throttle bodies. The main and auxiliary spindles are adapted for causing the main throttle body to close before the auxiliary throttle body reaches the auxiliary valve seat in a closing operation, and for causing the auxiliary throttle body to open before the main throttle body leaves the main valve seat in an opening operation.

Control valve for media in vapor or liquid form

A steam converting valve having spindle actuation includes a main valve a main seat and a main throttle body cooperating with the main valve seat for controlling a main steam flow. A common spindle actuator supplies thrust forces. A main spindle is associated with the main valve for transmitting the thrust forces to the main throttle body for opening and closing the main valve. An auxiliary valve has an auxiliary valve seat and an auxiliary throttle body cooperating with the auxiliary valve seat for controlling an atomizer steam flow. An auxiliary spindle is associated with the auxiliary valve for transmitting the thrust forces to the auxiliary throttle body for opening and closing the auxiliary valve. First and second spring elastic couplings respectively transmit the thrust forces for the main spindle and the auxiliary spindle to the main and the auxiliary throttle bodies. The main and auxiliary spindles are adapted to one another for causing the main throttle body to close before the auxiliary throttle body reaches the auxiliary valve seat, so that the main stream flow is blocked off upstream of the atomizer steam flow in a closing operation, and for causing the auxiliary throttle body to open the auxiliary valve before the main throttle body leaves the main valve seat, so that the atomizer steam flow develops upstream of the main steam flow in an opening operation.

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Herzogenaurach, Germany

Hermann Dorr