DE1226119B - Device for regulating the pressure of the heating medium in steam generators - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Number:
File number:
Registration date:
Display day:

F 22c

German KL: 13g-9

1226119
C 26178 I a / 13 g
February 7, 1962
October 6, 1966

The invention relates to a device for regulating the pressure of the heating medium in steam generators with one through which the working medium flows and preferably parallel to one Turbine arranged overflow line and with a pressure reduction valve arranged in this line, in which a pressure regulator with adjustable time behavior the overflow valve as a function the pressure in front of the valve when the state changes the working medium is adjusted from water to steam in order to keep this pressure constant, lan. the invention particularly relates to those devices of the above type which have a / - acting pressure regulator.

When starting up Benson boilers, it is known that the working fluid emerging from the boiler is - first water and later steam - via an overflow station arranged parallel to the turbine Returned to the water cycle until the working fluid reaches operating temperature and the turbines can be put into operation. It is required that the pressure of the Working medium in the boiler's start-up line is kept constant, regardless of whether water or steam is already flowing through the start-up line. For this purpose, the Boiler systems e.g. equipped with devices of the type mentioned at the beginning, in which - im As part of an automatic start-up program - the valves arranged in front of the overflow station can be adjusted depending on the pressure of the working medium in the start-up line, including pure P-controllers Find application.

Such an arrangement works satisfactorily if the constancy requirements are not too high of the pressure in the start-up line, as it is then possible to select the Proportional range of the controller to force a sufficient stability of the control loop. One often however, the desired reduction in the proportional range is due to the different behavior of the Control path in the water and steam phase of the working medium is not possible, otherwise the Transition of the working medium from the water to the vapor phase inadmissibly large pressure deviations from the pressure setpoint. It also shows that the regulation becomes unstable in the water phase.

It has therefore been considered to regulate the pressure of the working fluid in Anfahrleitungen of Benson-boilers / "/ - use regulators However, this proposal does not eliminate the existing difficulties, too, it is often undesirable, PI device for regulating the pressure of it..
warming equipment in steam generators

Applicant:

Continental Elektroindustrie Aktiengesellschaft,

Askania works,

Berlin 42, Großbeerenstr. 2-10

Named as inventor:

Dipl.-Ing. Lothar Stemme, Berlin;

Aloys Heisterkamp, Gelsenkirchen

To use regulators, because with such regulators there is no assignment between the respective valve position and the controlled variable is a parallel control of two or more overflow stations in the start-up line or starting lines are arranged, is not easily possible.

It has now been found that the F range when the working fluid passes from the water to the Vapor phase can be kept small or within the permissible limits, and on the other hand a sufficient one Stability of the control loop in the water phase can be achieved.

This is achieved according to the invention in that the time behavior of the pressure regulator is dependent is automatically adjusted by the currently present control range in such a way that a measured value of the Working medium temperature a temporary proportional range with increasing working medium temperature of the controller takes back, so that in the vapor phase of the working medium a P-acting Pressure regulation takes place.

It should be noted that it is known per se has to apply, the time behavior of a controller depending on the current control range to be adjusted automatically.

An exemplary embodiment of the invention is shown in greater detail below on the basis of the schematic representation described, in which an electrical controller with feedback is provided and the control of the Controller time behavior takes place in a manner known per se by intervening in the feedback.

The feed pump 1 of a Benson boiler feeds the initially liquid working medium into the superheater system 2 of the boiler. At the outlet of the boiler

vfL ·:; . : 609669/73

the working medium reaches via the line 3 in the normal operating case of the system via the valve 4 in a turbine 5 and from there into a condenser or into a low-pressure turbine connected downstream of the turbine od. Dgl..Beim.Anfahren the boiler, the valve 4 is blocked, and the first liquid working medium reaches the start-up line 6 Overcurrent station 7 and from there back into the water cycle. During the start-up process, the working medium pressure is in line 3, 6 to keep constant.

For the purpose of regulating the working medium pressure in lines 3, 6, station 7 contains an overflow valve, depending on the pressure of the working medium in line 3- in the sense of the regulation the working medium pressure can be adjusted. The pressure in the line 3 is measured by means of a pressure measuring device 10 converted into an electrical direct current which flows via line 11. In the Device 12, the pressure in line 3 is compared with its target value, and it flows through the Line 13 at the output of the device 12 is a direct current corresponding to the control deviation, the an amplifier 8 is supplied. The amplifier 8 is an electric or electro-hydraulic servomotor 9 downstream, the. the valve in the overflow station 7 adjusted.

For the purpose of bringing about a P-acting control, the controller is equipped with a feedback. The actuating gear of the motor 9 adjusts a position indicator 14, which is one of the positions of the valve controls the corresponding alternating voltage. The alternating voltage is via a timing element 14 'to the input of the control amplifier 8 as a direct voltage fed. The timer 14 'includes a proportionally transmitting device 17 and a Device 16 arranged parallel to 17, the transmission property of which has a resilient character. As a result of this design, the explained controller becomes a PZ controller in a manner known per se.

Since ¹ S the transmission rate of the device 16 is adjustable. To adjust the transmission rate, the servomotor 20 is provided, which acts on a potentiometer, the position of which is changed as a function of the temperature of the working medium in the line 3. To determine the working medium temperature, the electrical temperature measuring device 21 is provided, which is followed by the servomotor 20 on the output side. As the working medium temperature rises, the motor 20 adjusts the transfer rate of the device 16 in the sense of reducing the / proportion of the controller, so that finally the P / controller changes to a P controller at a certain adjustable working medium temperature.

Due to the explained mode of operation, the proportional range of the pressure regulator is exposed a permanent adjustable proportional range and a vanishing proportional range to * together, d. That is, the position feedback of the controller, through which the proportional band is determined switched once directly and once as a flexible feedback to the input of the controller. Of the The remaining proportional range is due to the permissible pressure deviation depending on the Load, while the temporary proportional range is dictated by the stability requirements will.

The control of the / -part of the P / controller can of course with a corresponding structure of the P / controller can also be done in other ways.

Claims (2)

. Patent claims: 1. Device for regulating the pressure of the heating medium in steam generators with one through which the working medium flows and is preferably arranged parallel to a turbine Overflow line and a pressure reduction valve arranged in this line the one pressure regulator with adjustable time behavior the overflow valve depending on the Pressure in front of the valve when the state of the working medium changes from water to steam adjusted in the sense of keeping this pressure constant, in particular device with a P / -acting pressure regulator, characterized in that the time behavior of the pressure regulator (10,12,8,9,14,16,17) is known per se Way automatically adjusted in this way depending on the current control range is that a measured value of the working medium temperature (2l) with increasing working medium temperature a temporary proportional range (16) of the controller takes back, so that in the vapor phase of the working fluid, a P-acting pressure control takes place. 2. Device according to claim I _5, characterized in that a controller with feedback is provided and the controller timing is controlled in a manner known per se by intervening in the feedback. Considered publications:
German patent specification No. 902 638. 1 sheet of drawings 609 669/73 9.66 © Bundesdruckerei Berlin