SU756052A1 - System for automatic regulating of overheated steam in power-producing unit - Google Patents

Description

The invention relates to a power system. The system can be used to optimize the pressure of superheated steam at the power units of the boiler-turbine with nozzle steam distribution.

Known control system of the unit, designed to maintain optimal pressure of superheated steam. This system contains a power regulator with functional transducers that form the settings for the vapor pressure regulator and the turbine valve position regulator [1].

The disadvantage of this system is the presence of complex functional converters.

Also known is a system for automatically controlling the pressure of superheated steam in a power unit, which contains series-connected master controllers for the position of turbine valves with a sensor and a setting device and a steam pressure regulator with a sensor [2]. This system is the closest to the invention of technical essence and the achieved result.

However, this system does not allow for the highest possible economy.

ti power unit. So, the combined mode provides for operation with nominal, minimum allowable and sliding vapor pressure at one specific number of open valves, and at optimum

₅ mode, the number of open valves varies depending on the load.

The aim of the invention is to increase efficiency by ensuring the optimal ratio of vapor pressure and valve position when the load changes.

This is achieved by the fact that the master controller is made with nonlinear feedback in the form of series-connected threshold elements, a trigger element and a control device. The control device is made in the form of a follower ¹⁵ but connected by an additional setting unit, switching and inertial elements.

FIG. 1 shows a structural diagram.

2o regulatory system; in fig. 2 - dependence of the optimum position of the valves b cd on the load; in fig. 3 - dependence of the optimal pressure P _o on the load of the power unit.

756052

The system includes a master controller 1, to the input of which a sensor 2 and a setpoint 3 of the position of valves 4 of the turbine 5 are connected. 8 and 9 form a mode selection device). For example, the output signal of the regulator 1 can serve as the position of the autosampling shaft, which controls the regulator 6. The threshold elements 7 and 8 are normally open limit switches. The output of the trigger element 9 is connected to the switching element 10 installed between the additional setting device 11 and the inertial element 12 (elements 10, 11 and 12 form a control device). The output of the inertial element is connected to the input of the regulator 1. To the input of the regulator 6 of the steam pressure is connected a sensor 13 of the vapor pressure in front of the turbine.

When the load decreases below Ν ₊ (see Fig. 3), opening the valves 4 of the turbine 5 initially becomes less than the set point and the regulator 1 increases its output signal, for example, switches on the autosampler engine, moving the shaft of the latter in the “more” direction and thereby reducing the setting 6. The latter reduces the vapor pressure, returning the valves 4 to the optimum position.

With a further decrease in load, the output of regulator 1 continues to increase. The vapor pressure decreases, and the valves in statics return to the optimum position. When the load is N g, the threshold element 7 switches the trigger element 9. The latter, acting on the switching element 10, connects an additional unit 11 through the inertial element 12 to the master controller 1. The controller 1 begins to reduce its output signal, and the controller 6 accordingly increases the pressure with the task steam, closing valves 4 of the turbine 5. The vapor pressure changes from point a (Fig. 3) to point b / a. valves move from one optimal position (opening two groups, point a

in fig. 2) to another optimal position (opening of one group, point b in Fig. 2). With a further decrease in the load, the output signal of the regulator 1 increases again, and the vapor pressure decreases accordingly.

With increasing load, reverse processes occur. When N — Ν _{Β, the} threshold element 8 switches the trigger element 9, the latter through the switching element 10 disconnects the additional unit 11 from the controller 1, increasing the reference to the latter. Knob 1 increases its output. The block again goes to work with two groups of open valves (valves move from point in to point d in Fig. 2, the pressure decreases from point in to point d 'in Fig. 3).

This system allows the unit to operate in the mode of the optimal ratio of vapor pressure and the position of the turbine valves.

Claims (2)

Claim 1. System for automatic regulation of superheated steam pressure in a power unit, containing a series-connected master control valve for the position of turbine valves with a sensor and a setting device and a steam pressure controller with a sensor, characterized in that, in order to improve efficiency by ensuring an optimum ratio of steam pressure and valve position load, the master controller is made with nonlinear feedback in the form of serially connected threshold elements, a trigger element and a control stroystva. 2. System by π. 1, characterized in that the control device is made in the form of a serially connected additional setting, switching and inertial element.