SU842336A1 - Drum-type steam generator feed controller - Google Patents

Description

(54) POWER SUPPLY REGULATOR OF THE DRUM STEAM GENERATOR

I

The invention relates to heat and power engineering, in particular, to the regulation of the power supply of a drum-type steam generator.

Known regulators of a drum-type steam generator are those that contain drum water level sensors, steam and feedwater flow rates, which are connected to a control device connected via a servo drive to the feedwater flow regulator 1.

However, the known controllers do not have sufficient reliability due to the fact that during their adjustment it is necessary to solve the problem of maintaining the level within safe limits to the detriment of the quality of control of the feedwater flow.

The purpose of the invention is to increase reliability by reducing fluctuations in feedwater consumption.

The goal is achieved by the fact that the controller additionally contains a non-linear transducer connected between the level sensor and the control device.

In this case, the nonlinear converter is made in the form of two signal sources

and a fast-lining element, the latter being connected by the input to the output of one of the sources, and the output to the output of the second source is counter.

Fig. 1 is a block diagram of this controller; in fig. 2 - the same non-linear converter.

The power regulator of the drum steam generator (Fig. 1), as well as the usual one, includes a level 1 sensor measuring the level deviation D N in the drum from the average position, the steam flow sensor 2 measuring the load D of the steam generator; a water flow sensor 3 measuring the feed water supply W to the steam generator. The sensor signals are fed to the input of the control device 4, in which they are transformed and algebraically summed, and the law of regulation is formed. The device 4 through the servo 5 and the regulator 6 changes

feed water consumption. In contrast to the signal level signal usual in this controller, it additionally contains a nonlinear converter 7 with a static characteristic such as a power function.

The power regulator works as follows.

With all the changes in the controlled parameters caused by any disturbances, the regulator affects the feedwater flow, bringing the system to a new equilibrium state. The control action closes on the high-speed loop: device 4 - servo 5 - regulator 6 - water flow W - sensor 3 - device 4. If the material balance between the steam and water consumption is disturbed at a given level position, the regulator quickly restores the balance. If there is a level deviation, the controller itself creates a material imbalance between the steam and water consumption, by which the level returns to the desired position. The control action in this case is closed not only by the fast-acting but also by the inertial circuit: device 4 - servo 5 - regulator 6 - water flow W - level H - sensor 1 - nonlinear converter 7 - device 4.

Thus, the proposed power regulator, like the known ones, behaves in dynamics as a regulator with a rigid feedback on the flow of feed water. But, unlike the known ones, it has a variable gain factor along the level measurement channel, which increases as the level deviation from the target position increases.

Under normal operating conditions, when the level deviations are small in size and perfectly safe for the equipment, the power regulator operates with a low level gain factor. It slowly returns to equilibrium, but at any load it provides feedwater with minimal flow fluctuations.

In emergency or other situations accompanied by significant level deviations, the gain and speed of the controller increase dramatically, so it forces changes in feed water flow and ensures the safety of the installation.

Therefore, the introduction into the circuit of a three-pulse power regulator of the nonlinear converter 7 allows one to fulfill the contradictory requirements imposed on the adjustment of the regulator. By changing the shape of the static characteristic of the converter, you can achieve optimal tuning.

regulator for both characteristics of the steam generator modes. In addition, the power controller acquires some properties of variable structure regulators: it becomes less sensitive to changes in tuning parameters (the ratio of gain factors in level and flow rate) and the dynamic characteristics of the object.

Nonlinear converter 7 (Fig. I) may have a very different device. FIG. 2 shows a block diagram of one variant of the converter, which consists of a transformer with one primary (I) and two secondary (II and III) windings and a fast-sizing element 8. The input of the fast-sluicing element is connected to winding II, and its output is connected opposite to winding III.

The fast-filling element of the BNE can also have a very different device. For example, it can be used as an amplifier. Thus, the use of the proposed controller makes it possible to increase the reliability of the controller by reducing fluctuations in the feed water flow.

Claims (2)

1. A drum steam generator power regulator containing drum water level sensors, steam and feedwater flow rates associated with a control device connected via a servo drive to the feed water flow regulator, characterized in that in order to increase reliability by reducing oscillations feedwater flow rate, the controller further comprises a non-linear transducer connected between the level sensor and the control device. 2. The regulator according to claim 1, characterized in that the non-linear converter is made in the form of two signal sources and a high-speed element, the latter being connected to the output of one of the sources and the output to the output of the second source. Sources of information taken into account in the examination 1. Pletnev G. P. Automatic control and protection of thermal power plants. M., “Energie, 1970, p. 301, fig. 346.