SU1758335A1 - Overheated steam temperature automatic control system - Google Patents

Abstract

Use: automate heat and power processes. SUMMARY OF THE INVENTION: A system for automatically controlling the temperature of superheated steam, containing a control valve 16 for injecting cooling water into a desuperheater 1, connected via an actuator to the output of controller 6 with a dynamic parameters adjusting unit 8, a sensor 4 of adjustable temperature, connected to controller 6 and The temperature sensor 11 l ara behind the desuperheater 1, connected to the input of the regulator 6 through the differentiator 13, additionally contains blocks 9 and 10 p sequentially interconnected prediction and extremum, the input of the first is connected to the output of the adjustable temperature sensor 4, and the output of the second - to the input of the dynamic parameters adjustment unit 8. 1 il.

Description

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The invention relates to the automation of heat and power processes, in particular to the regulation of the temperature of superheated steam.

A known system for automatic adjustment of steam parameters behind an energy boiler, comprising an injection valve connected to a temperature controller, the inputs of which are connected to a sensor and a steam temperature sensor, and 10 a steam valve connected to a pressure controller connected to a pressure regulator and pressure sensor.

A system is known for automatically regulating steam steam parameters for a power engineering boiler, which contains an injection valve connected to a temperature controller, the inputs of which are connected to a setpoint and a temperature sensor, a steam valve and a steam valve connected to a pressure regulator connected to §8de A sensor and a pressure sensor, two nonlinear units of which are inserted into the communication line of the pressure sensor with a pressure regulator, and through another nonlinear element a temperature sensor 25 pbc is connected to the pressure regulator. -.

A known system for automatically controlling the temperature of superheated steam, containing a coolant injection valve, controlled by a regulator, is connected with a variable temperature sensor and, via a differentiator, with steam temperature sensors behind the desuperheater, which is additionally equipped with a block 35 adjusting the dynamic parameters of the temperature of the cooling medium.

However, this system of automatic control of the superheated steam temperature does not provide a high quality 40 stabilization of the controlled parameter, since it does not take into account the trends in the temperature of the superheated steam and does not adjust the dynamic parameters for this indicator.

The purpose of the invention is to improve the accuracy of controlling the temperature of superheated steam, thereby improving the quality of regulation.

The goal is achieved by the fact that the 50 system of automatic control of the superheated steam temperature, containing the cooling water injection control valve to the desuperheater, connected via an actuator to the controller output, to a dynamic temperature control unit, connected to the controller input and a steam temperature sensor behind the desuperheater connected to

through the differentiator to the regulator input, it additionally contains prediction and extremum blocks connected in series with each other, the input of the first is connected to the output of the adjustable temperature sensor, and the output of the second is connected to the input of the dynamic parameters tuning unit.

The drawing is a schematic diagram of a system for automatically controlling the temperature of superheated steam.

An automatic superheated steam temperature control system contains a desuperheater 1, an output section of a superheater 2 and a main steam line 3, on which a temperature sensor 4 with a converter 5 is connected to temperature controller 6 connected to a setting device 7, a unit 8 for adjusting dynamic parameters connected to prediction blocks 9 and extremum extraction 10 are connected in series with each other, and prediction block 9 is connected via a transducer 5 to a temperature sensor. The temperature controller b is also connected to the steam temperature sensor 11 downstream of the desuperheater through serially connected converter 12 and differentiator 13. The temperature controller 6 through the actuator 14 equipped with a position indicator 15. is connected to the cooling water injection control valve 1b.

The system for automatically controlling the temperature of superheated steam works as follows.

When the temperature of superheated steam in the main steam line 3, measured by temperature sensor 4 with converter 5, deviates, a signal is sent to the adder of the temperature controller adder, where signals from the steam temperature sensor 11 behind the desuperheater through the converter 12 and the differentiator 13 and from the transmitter 7. The error signal is processed by the temperature controller 6, which controls, using an actuator 14, equipped with a position indicator 15, the movement of the regulating valve 16 for cooling water injection. joining system of controlling temperature of superheated steam in ustanovivshees state. Dynamic parameter adjustment unit 8 (k - Ti gain - constant integration) serves to increase the degree of stabilization of the superheated steam temperature depending on the changing dynamic characteristics of the desuperheater with the output section of the superheater (K - gain factor, latency time and T - constant time ). The changing dynamic characteristics of the object (superheater 1 with the output section of the superheater 2) affect the current temperature of the superheated steam in the main steam line 3, measured by sensor 4 with converter 5, the signal from which enters the prediction unit 9. The prediction unit 9 allows to determine a quantitative assessment of the quality of stabilization of the controlled parameter of the superheated steam temperature; in this case, determine the amount of temperature outliers beyond the specified limits at a certain time m range based on the problem solving emission

p 2T

W (o2 + / 82) 2 p and

where T is the predicted time interval;

o2 is the dispersion of the controlled parameter;

a is the decay rate of the autocorrelation function;

ft is an indicator of the oscillation of the autocorrelation function;

a is the limit of variation of the monitored parameter.

The signal from the output of the prediction unit 9 is fed to the input of the extremum extraction unit 10, where a search is performed. Optimal values of k - gain and Ti - constant integration, based on the fact that at the extremum point

five

0

five

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Dent of the function (temperature of superheated steam) is zero, i.e. grad F Oh

The found optimal values of k and TI are fed to block 8 for adjusting the dynamic parameters, which ensures the formation of these values by the temperature controller 6.

Minimizing the p (the number of outliers of the controlled parameter beyond the specified limits over a certain time interval) by changing the dynamic parameters (k, TI) of the controller b settings provides a high degree of stabilization of the superheated steam temperature with regard to the changing trend of deviation of the controlled parameter.

Claims (1)

Claims An automatic superheated steam temperature control system, comprising a cooling water injection control valve for a desuperheater, connected via an actuator to the controller output to a dynamic parameter adjusting unit, a variable temperature sensor connected to the regulator input, and a steam temperature sensor behind the desuperheater connected To the input of the regulator through the differentiator, it is in order with that. what. In order to increase the control accuracy, the system additionally contains prediction and extremum blocks connected in series, the input of the first one is connected to the output of the adjustable temperature sensor, and the output of the second is connected to the input of the dynamic parameters tuning unit.