RU2620612C2 - Drum boiler superheated steam automatic temperature control system - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: system is introduced by the differentiator and correcting unit that changes the regulator dynamic configuration parameters in the automatic temperature control system of superheated drum boiler steam depending on the steam temperature in the steam chamber.

EFFECT: improved quality of maintaining the temperature of the superheated steam at the outlet of the boiler drum superheater in the boiler transient condition - change of the thermal load.

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Description

The invention relates to automatic control systems for drum power boilers and can be used to improve the quality of temperature control of superheated steam.

The two-pulse system for automatically controlling the temperature of superheated steam is widely known [Klyuev A.S., Lebedev A.T., Novikov S.I. Adjustment of automatic control systems for steam boilers. - M .: Energoatomizdat, 1985. P. 94] containing a PI controller, a differentiator, two temperature sensors, an injection control valve and the connections between them.

The main disadvantage of such a system is the low quality of transients with external perturbations and perturbations in the steam load.

There is also known a system for automatically controlling the temperature of superheated steam of a drum boiler [Patent RU 36720, IPC F22B 35/00, 2006.01], comprising a reheater of a drum boiler with a steam line, a temperature sensor installed in the superheater, an actuator installed on the steam line of the superheater and changing the amount of condensate, a superheater injected into the steam pipe, a temperature controller and a temperature controller, made in the form of a proportionally integrating unit, a correction unit and I do them.

The disadvantage of this system is the poor quality of work with a significant delay of the object and a slight change in the parameters of the transfer function of the heating surface along the channel of the regulatory action. Such a control system is sensitive to changes in parameters that occur under the influence of uncontrolled internal disturbances and with large delays of the object along the channel of the regulatory action, it cannot compensate for the harmful effect of delay on the stability and quality of the regulation process.

Also known are temperature control systems for the temperature of the superheated steam of a drum boiler [Patent RU 139014, IPC F22B 35/00, 2006.01] and [Patent RU 143268, IPC F22B 35/00, 2006.01] which are the prototype systems [Patent RU 36720, IPC F22B 35/00, 2006.01], comprising a superheater of a drum boiler with a steam line, a temperature sensor, an executive unit, a temperature setter, a temperature controller, in the first case it is an adaptive controller with an input stabilization signal through the control channel, in the second case a neuro-PID controller and communication between them.

The disadvantages of such systems are the low speed when controlling the temperature of superheated steam, increased sensitivity to internal disturbances, and in these systems the required control accuracy is not achieved.

The prototype of the proposed solution is a temperature control system for superheated steam, performing multi-stage regulation [G. Kulakov, M. Gorelysheva Study of the influence of the quality of temperature control of superheated steam on the service life of the boiler superheater metal // News of Universities and Energy Associations of the CIS - Energy. - 2009. - No. 4. - S. 62-69], containing a control object (superheater), consisting of two control sections, four temperature sensors, a flow sensor, two differentiators, two temperature controllers, two control valves, a backlash type sensor, a position sensor for the second valve , a device for correcting dynamic settings and the relationship between them.

The disadvantages of this system are the deterioration in the temperature control of superheated steam with a stepwise decrease in heat load due to an increase in the dynamic control error, a decrease in the service life of the superheater metal in connection with the approach of the injection site to the outlet of the superheater and, as a result, possible dropping of moisture drops from the unworked cooling medium into the steam line . In practice, in relation to powerful boilers with a developed superheater, technologists, for this particular case, it is necessary to refuse to use the second temperature controller along the steam, based on the above statements, therefore, introducing a signal by the valve position does not make sense. UKPDN, correcting the dynamic settings of regulators and differentiators according to the function of steam flow, does not determine the dependence of the output parameter on the quality of its regulation.

The task to which the claimed invention is directed is to improve the quality of maintaining the temperature of the superheated steam of a drum boiler, not only in a stationary mode, but also in transient modes of operation - changing the heat load.

The solution to this problem is achieved by the fact that the automatic temperature control system of the superheated steam of the drum boiler contains a control object - a superheater, consisting of two control sections, an unregulated section and a steam chamber, five temperature sensors, three differentiators, two temperature controllers, two control valves, two temperature regulators, made in the form of proportionally integrating blocks, where the second controller along the steam maintains the temperature at the inlet section, and a correction unit that changes the dynamic settings of the regulators in the automatic temperature control system of the superheated steam of the drum boiler, depending on the temperature of the steam in the steam collection chamber.

In FIG. 1 is a block diagram of a system for automatically controlling the temperature of an overheated steam of a drum boiler.

The automatic temperature control system for the superheated steam of a drum boiler consists of: a superheater, consisting of two control sections 1, 8, an unregulated section 15 and a steam collection chamber 16, temperature sensors 2, 3, 9, 10, 17, differentiators 4, 11, 18, regulators temperature 5, 12, control valves 6, 13, temperature adjusters 7, 14, correction block 19.

Steam sequentially passes through adjustable sections 1 and 8, the unregulated section 15 acquires the parameters of superheated steam and enters the steam collection chamber 16, and then into the steam line, where the steam temperature should be kept within narrow limits.

The automatic temperature control system of the superheated steam drum boiler operates as follows.

The output signal of the temperature sensor 2 is fed to the input of the differentiator 4. At the first input of the temperature controller 5, a signal is received from the differentiator 4 according to the rate of change of temperature 4. The signal from the temperature setter 7 is received at the second input of the temperature controller 5. The signal from the sensor is sent to the third input of temperature controller 5 3. The fourth input of the temperature controller 5 receives a signal from the output of the correction unit 19. The output signal of the temperature controller 5 in the form of a control signal is fed to the input of the valve 6, which changes the amount of condensate injected into the steam line.

The output signal of the temperature sensor 9 is fed to the input of the differentiator 11. At the first input of the temperature controller 12, a signal is received from the differentiator 11 according to the rate of change of temperature 11. The signal from the temperature setter 14 is received at the second input of the temperature controller 14. A signal from the sensor is supplied to the third input of temperature controller 12 temperature 10. The fourth input of the temperature controller 12 receives a signal from the output of the correction unit 19. The output signal of the temperature controller 12 in the form of a control signal is fed to the input of the control valve 13, which changes the amount of condensate injected into the steam line.

The output signal of the temperature sensor 17, installed in the steam chamber 16, is fed to the input of the differentiator 18, which generates a signal for the rate of change of temperature supplied to the input of the correction unit 19. The correction unit 19 generates a dynamic adjustment signal for the regulators 5 and 12.

Thanks to this design, the model of the automatic temperature control system for the superheated steam of the drum boiler ensures that the latter is maintained at an acceptable level in the superheater sections, which is automatically changed depending on the steam load and other operating conditions of the boiler.

Claims (1)

An automatic temperature control system for the superheated steam of a drum boiler containing a control object - a superheater consisting of two control sections, an unregulated section and a steam chamber, five temperature sensors, two differentiators, two temperature controllers, two control valves, two temperature controllers, made in the form of a proportional -integrating units, where the second controller along the steam maintains the temperature at the inlet to the unregulated section, characterized in that a differentiator and a correction unit have been introduced that changes the parameters of the dynamic adjustment of the regulators in the system for automatically controlling the temperature of the superheated steam of a drum boiler, depending on the temperature of the steam in the steam collection chamber.

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