CN114992629B - Combustion control system and method for circulating fluidized bed boiler - Google Patents
Combustion control system and method for circulating fluidized bed boiler Download PDFInfo
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- CN114992629B CN114992629B CN202210895786.2A CN202210895786A CN114992629B CN 114992629 B CN114992629 B CN 114992629B CN 202210895786 A CN202210895786 A CN 202210895786A CN 114992629 B CN114992629 B CN 114992629B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/18—Details; Accessories
- F23C10/28—Control devices specially adapted for fluidised bed, combustion apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
- F22D5/26—Automatic feed-control systems
- F22D5/30—Automatic feed-control systems responsive to both water level and amount of steam withdrawn or steam pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/02—Regulating fuel supply conjointly with air supply
- F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Abstract
The embodiment of the invention provides a circulating fluidized bed boiler combustion control system and a circulating fluidized bed boiler combustion control method, relates to the technical field of boiler combustion, and solves the problem of environmental pollution caused by insufficient combustion of a circulating fluidized bed boiler. The system comprises an optimizing controller and a base layer controller connected with the optimizing controller, wherein the optimizing controller is used for calculating and outputting an optimizing wind-coal ratio in real time according to a preset optimizing target, and the base layer controller is used for realizing combustion control of the circulating fluidized bed boiler according to the optimizing wind-coal ratio calculated by the optimizing controller. The invention is used for the combustion control of the online circulating fluidized bed boiler, adopts the multivariable predictive control technology of a double-layer controller, realizes the multivariable decoupling and the advanced pre-judgment and the advanced adjustment of key variables, further realizes the optimal combustion of the online circulating fluidized bed boiler, ensures that the coal dust is fully combusted, improves the combustion efficiency of the boiler, and effectively realizes the long-period unmanned operation and the energy conservation and consumption reduction of the circulating fluidized bed boiler under the normal production of the boiler.
Description
Technical Field
The invention relates to the technical field of boiler combustion, in particular to a circulating fluidized bed boiler combustion control system and a circulating fluidized bed boiler combustion control method.
Background
Circulating fluidized bed boilers (Circulating Fluidized Bed Boiler, CFB) have taken a considerable share in small and medium boilers since the beginning of the 80 s of the 20 th century in the commercial market of coal-fired boilers, which are produced using pulverized coal of larger particle size as raw material to generate steam for turbine power generation or for other heat users.
Along with the continuous development of the economy in China, the environmental pollution problem is more and more serious, wherein, as the carbon emission of the combustion of the circulating fluidized bed boiler is larger, the automation level of the circulating fluidized bed boiler needs to be comprehensively improved, the production is refined, the production is carried out by clamping edges, the production is stable, and the energy is saved and the consumption is reduced. In the automatic optimization control of the circulating fluidized bed boiler, the combustion control system is the most important, so that the design of the combustion control system is needed to realize the optimal combustion of the circulating fluidized bed boiler, and the problem of environmental pollution caused by the combustion of the existing circulating fluidized bed boiler is solved.
Disclosure of Invention
The present specification provides a circulating fluidized bed boiler combustion control system and method thereof for overcoming at least one technical problem existing in the prior art.
According to a first aspect, embodiments of the present specification, there is provided a circulating fluidized bed boiler combustion control system, comprising:
the optimization controller is used for calculating and outputting an optimized wind-coal ratio in real time according to a preset optimization target;
the base layer controller is connected with the optimizing controller and is used for realizing combustion control of the circulating fluidized bed boiler according to the optimized wind-coal ratio calculated by the optimizing controller;
wherein the optimization controller and the base layer controller are both model-based predictive controllers.
Preferably, the preset optimizing targets of the optimizing controller comprise oxygen content and ton coal steam production, the input of the optimizing controller is heat value compensation quantity and actual wind-coal ratio, the output of the optimizing controller is the optimizing wind-coal ratio, and the optimizing controller corrects the output optimizing wind-coal ratio according to the heat value compensation quantity.
Preferably, the base layer controller includes:
the feedback correction module is connected with the circulating fluidized bed boiler system and is used for collecting actual process parameters;
the model prediction module is connected with the feedback correction module and is used for correcting a model prediction output value according to the actual process parameter;
the output end of the basic layer dynamic solver is respectively connected with the model prediction module and the circulating fluidized bed boiler system, the input value of the basic layer dynamic solver is the difference value between the corrected model prediction output value and the control target, and the output value is the boiler combustion control quantity; the boiler combustion control quantity comprises coal feeding quantity, primary air quantity, secondary air quantity, air intake quantity and water feeding quantity.
Further preferably, the actual process parameters include an actual drum liquid level value, an actual air-coal ratio, a main steam pressure value, a main steam temperature value and a furnace pressure value, and the corrected model prediction output values include a drum liquid level predicted value, an air-coal ratio predicted value, a main steam pressure predicted value, a main steam temperature predicted value and a furnace pressure predicted value;
the control targets comprise a drum liquid level control target, a main steam pressure control target, a main steam temperature control target and a hearth pressure control target;
the input values of the basic layer dynamic solver are the difference value between the steam drum liquid level predicted value and the steam drum liquid level control target, the difference value between the main steam pressure predicted value and the main steam pressure control target, the difference value between the main steam temperature predicted value and the main steam temperature control target, the difference value between the hearth pressure predicted value and the hearth pressure control target and the difference value between the wind-coal ratio predicted value and the optimized wind-coal ratio.
In a second aspect, according to embodiments of the present specification, there is provided a combustion control method of a circulating fluidized bed boiler, including:
setting a preset optimization target, and calculating an optimized wind-coal ratio in real time by utilizing an optimization controller according to the preset optimization target;
inputting the optimized wind-coal ratio calculated in real time into a base layer controller, and realizing combustion control of the circulating fluidized bed boiler by utilizing the base layer controller according to the optimized wind-coal ratio; wherein the optimization controller and the base layer controller are both model-based predictive controllers.
Preferably, the setting a preset optimization target, and calculating, in real time, an optimized wind-coal ratio by using an optimization controller according to the preset optimization target specifically includes:
setting a preset optimization target; the preset optimization targets comprise oxygen content and ton coal steam production;
and inputting the heat value compensation quantity and the actual wind-coal ratio into an optimization controller, calculating the output wind-coal ratio in real time by the optimization controller according to the preset optimization target, and correcting the output wind-coal ratio according to the heat value compensation quantity to obtain the optimized wind-coal ratio.
Preferably, the inputting the optimized wind-coal ratio calculated in real time into a base layer controller, and the realizing the combustion control of the circulating fluidized bed boiler by using the base layer controller according to the optimized wind-coal ratio specifically comprises:
setting a control target, and inputting the optimized wind-coal ratio into a base layer controller;
collecting actual process parameters of a circulating fluidized bed boiler system, and correcting a model prediction output value according to the actual process parameters;
comparing the corrected model prediction output value with the control target, and then inputting the difference value between the corrected model prediction output value and the control target into a basic-level dynamic solver of the basic-level controller to obtain the boiler combustion control quantity; the boiler combustion control quantity comprises coal supply quantity, primary air quantity, secondary air quantity, air intake quantity and water supply quantity;
and conveying the boiler combustion control quantity to the circulating fluidized bed boiler system so that the circulating fluidized bed boiler system can regulate and control the combustion of the circulating fluidized bed boiler according to the boiler combustion control quantity.
Further preferably, the actual process parameters include an actual drum liquid level value, an actual air-coal ratio, a main steam pressure value, a main steam temperature value and a furnace pressure value, and the corrected model prediction output values include a drum liquid level predicted value, an air-coal ratio predicted value, a main steam pressure predicted value, a main steam temperature predicted value and a furnace pressure predicted value; the control targets comprise a drum liquid level control target, a main steam pressure control target, a main steam temperature control target and a hearth pressure control target;
comparing the corrected model predictive output value with the control target specifically includes:
and comparing the steam drum liquid level predicted value with the steam drum liquid level control target, the main steam pressure predicted value with the main steam pressure control target, the main steam temperature predicted value with the main steam temperature control target, the hearth pressure predicted value with the hearth pressure control target, the wind-coal ratio predicted value with the optimized wind-coal ratio respectively to obtain a difference value of the steam drum liquid level predicted value with the steam drum liquid level control target, a difference value of the main steam pressure predicted value with the main steam pressure control target, a difference value of the main steam temperature predicted value with the main steam temperature control target, a difference value of the hearth pressure predicted value with the hearth pressure control target and a difference value of the wind-coal ratio predicted value with the optimized wind-coal ratio.
The beneficial effects of the embodiment of the specification are as follows:
the multi-variable predictive control technology of the double-layer controller can realize the advanced pre-judgment and advanced adjustment of key variables by adopting the two-layer model-based predictive controller, and can realize multi-variable decoupling, the basic-layer controller completes the automatic control of basic functions, the optimization controller calculates the optimized wind-coal ratio on line in real time, the optimal combustion of the on-line circulating fluidized bed boiler is realized, the pulverized coal is fully combusted, the combustion efficiency of the boiler is improved, and the long-period unmanned operation and the energy conservation and consumption reduction of the circulating fluidized bed boiler can be effectively realized under the normal production of the boiler.
Drawings
In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of a combustion control system of a circulating fluidized bed boiler according to an embodiment of the present disclosure;
FIG. 2 is a functional block diagram of a base layer controller in a circulating fluidized bed boiler combustion control system provided in an embodiment of the present disclosure;
fig. 3 is a schematic flow chart of a combustion control method of a circulating fluidized bed boiler according to an embodiment of the present disclosure.
Detailed Description
The technical solutions of the embodiments of the present specification will be clearly and completely described below with reference to the drawings of the embodiments of the present specification, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.
It should be noted that the terms "comprising" and "having" and any variations thereof in the embodiments and figures herein are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
The circulating fluidized bed boiler system mainly comprises an air supply and induction system, a combustion system and a steam-water system, and the combustion and steam-water processes of the boiler are very complex and are influenced by various factors due to the characteristics of the circulating fluidized bed boiler system, and the combustion system and the steam-water system are strong in mutual association and coupling. The circulating fluidized bed boiler is a control object of multiple variables, interrelations, nonlinearities, time-varying and distribution parameters, and changing one parameter affects several parameters at the same time, so that the control difficulty is high.
In the prior art, most circulating fluidized bed boilers utilize a PID (Proportion Integration Differentiation) algorithm based on a distributed control system (Distributed Control System, DCS), and utilize a feedforward control strategy to play a certain decoupling role, but it is difficult to realize true multivariable decoupling, that is, it is difficult to realize automatic control adjustment by utilizing a conventional control strategy of the DCS system, and on-site operators manually adjust and perform real-time prejudgement, so that the combustion system is difficult to maintain the optimal combustion control working condition, that is, the single-layer multivariable predictive controller is difficult to realize optimal control of the real-time oxygen-coal ratio. In addition, some circulating fluidized bed boilers are additionally provided with an externally-hung PID control strategy and a black box optimizer on the basis of a basic PID algorithm and a feedforward control strategy in a DCS system, and the control system is very inconvenient to maintain and has high cost.
In view of the above problems, embodiments of the present specification disclose a circulating fluidized bed boiler combustion control system. The following will describe in detail.
Fig. 1 illustrates a circulating fluidized bed boiler combustion control system provided in accordance with an embodiment of the present specification. As shown in fig. 1, the system includes: the system comprises an optimizing controller and a base layer controller connected with the optimizing controller, wherein the optimizing controller is used for calculating an optimizing wind-coal ratio in real time according to a preset optimizing target, and conveying the calculated optimizing wind-coal ratio to the base layer controller, and the base layer controller is used for realizing combustion control of the circulating fluidized bed boiler according to the optimizing wind-coal ratio conveyed by the optimizing controller.
In an embodiment, the optimization controller and the base layer controller are model-based prediction controllers, the combustion control system of the circulating fluidized bed boiler is built by using the existing multivariable prediction control technology, the algorithm is stable, the maintenance is convenient, and the control of the oxygen-coal ratio can realize real-time automatic optimization and adjustment.
In the embodiment, the optimizing controller and the base layer controller are model-based predictive controllers, namely, the circulating fluidized bed boiler adopts a combustion optimizing double-layer pre-estimated controller structure, the base layer controller adopts a model-based control technology, and the optimizing controller also adopts a model-based optimizing technology, so that the multivariable decoupling intelligent optimizing control function of the air supply and induction system, the combustion system and the steam-water system is realized, and the optimizing controller is one of innovation points of the embodiment of the invention.
The combustion control system of the circulating fluidized bed boiler adopts a multi-variable pre-estimated control technology of a double-layer controller, so that the advanced pre-judgment and advanced adjustment of key variables are realized, and the multi-variable decoupling is realized.
Specifically, the optimization controller is used as an optimizer of the circulating fluidized bed boiler, and is combined with an optimal objective function to realize online real-time calculation of the optimized wind-coal ratio so as to realize the optimal combustion of the online circulating fluidized bed boiler. In a specific embodiment, as shown in fig. 1, the preset optimizing targets of the optimizing controller include oxygen content and ton coal steam generating amount, the input of the optimizing controller is a heat value compensating amount and an actual wind-coal ratio conveyed by the base layer controller, the output of the optimizing controller is an optimized wind-coal ratio, wherein the preset optimizing targets (i.e. oxygen content and ton coal steam generating amount) of the optimizing controller are set by an operator according to the actual condition of the operation of the boiler, the heat value compensating amount is determined according to the external environment of the operation of the boiler, the optimizing controller calculates the optimized wind-coal ratio in real time according to the actual wind-coal ratio and the preset optimizing targets, and the calculated optimized wind-coal ratio is corrected according to the current heat value compensating amount to obtain the finally output optimized wind-coal ratio.
It should be noted that the preset optimization targets in the above description may include only two optimization targets of oxygen content and ton coal steam production, and may also include other optimization targets besides oxygen content and ton coal steam production, which is not limited in this embodiment.
In the embodiment of the invention, the basic layer controller is used for completing control of basic functions, and specifically comprises intelligent control (load change) of main steam pressure, automatic control of main steam temperature, automatic control of drum liquid level, automatic control of wind-coal ratio and automatic control of hearth pressure, wherein an optimization target value is an optimized wind-coal ratio calculated and optimized by an optimization controller in real time and a set control target.
In a specific embodiment, as shown in fig. 2, the base layer controller includes: the system comprises a feedback correction module, a model prediction module and a basic layer dynamic solver, wherein the input end of the feedback correction module is connected with a circulating fluidized bed boiler system, the output end of the feedback correction module is connected with the model prediction module, the output end of the basic layer dynamic solver is respectively connected with the model prediction module and the circulating fluidized bed boiler system, the feedback correction module is used for collecting actual process parameters of the circulating fluidized bed boiler system and feeding back the actual process parameters of a boiler to the model prediction module, meanwhile, the model prediction module is used for collecting the actual boiler combustion control quantity executed, the model prediction module is used for correcting the model prediction output value according to the actual process parameters, the difference value between the corrected model prediction output value and a control target is used as the input value of the basic layer dynamic solver, the basic layer dynamic solver calculates and outputs the current required boiler combustion control quantity according to the current input value, and the circulating fluidized bed boiler system is adjusted according to the boiler combustion control quantity output by the basic layer dynamic solver so as to realize the optimal combustion of the online circulating fluidized bed boiler. The boiler combustion control quantity comprises, but is not limited to, coal feeding quantity, primary air quantity, secondary air quantity, air intake quantity and water feeding quantity.
In a specific implementation process, the actual process parameters include an actual drum liquid level value, an actual air-to-coal ratio, a main steam pressure value, a main steam temperature value and a furnace pressure value, the corrected model prediction output values include a drum liquid level prediction value, an air-to-coal ratio prediction value, a main steam pressure prediction value, a main steam temperature prediction value and a furnace pressure prediction value, the control targets include a drum liquid level control target, a main steam pressure control target, a main steam temperature control target and a furnace pressure control target, the corrected model prediction output values and the control targets are respectively compared one by one to respectively obtain a difference value of the drum liquid level prediction value and the drum liquid level control target, a difference value of the main steam pressure prediction value and the main steam pressure control target, a difference value of the main steam temperature prediction value and the main steam temperature control target, a difference value of the furnace pressure prediction value and the furnace pressure control target, and a difference value of the air-to-coal ratio prediction value and an optimized air-to-coal ratio, and are used as input values of the base layer dynamic solver.
In the embodiment of the invention, the combustion control system of the circulating fluidized bed boiler adopts a double-layer model-based predictive controller to solve the problems of combustion optimization, drum liquid level and variable load automatic control of the circulating fluidized bed boiler, and ensures that the pulverized coal of the boiler is fully combusted by optimizing the air-coal ratio without overlarge air quantity, thereby improving the combustion efficiency of the boiler and reducing smoke discharge loss. Under the normal working condition of the circulating fluidized bed boiler, the combustion control system of the circulating fluidized bed boiler can realize long-period unmanned operation of the device, and in addition, the overall stability and the efficiency of the boiler can be improved, so that the energy is saved, the consumption is reduced, and the practicability is strong.
The embodiment of the specification also discloses a combustion control method of the circulating fluidized bed boiler, as shown in fig. 3, comprising the following steps:
step 100: setting a preset optimization target, and calculating an optimal wind-coal ratio in real time by utilizing an optimization controller according to the preset optimization target.
The optimization controller is an optimizer of the circulating fluidized bed boiler, is a model-based prediction controller and is used for realizing online real-time calculation of the optimized wind-coal ratio by combining with an optimal objective function.
Specifically, a preset optimization target is set; and inputting the heat value compensation quantity and the actual wind-coal ratio into an optimization controller, calculating the output wind-coal ratio in real time by the optimization controller according to a preset optimization target, and correcting the output wind-coal ratio according to the heat value compensation quantity to obtain the optimized wind-coal ratio. Wherein the preset optimization targets include, but are not limited to, oxygen content and ton coal steam production.
In a specific implementation process, an operator performs a preset optimization target according to the actual condition of boiler operation, the input of the optimization controller is the heat value compensation quantity and the actual wind-coal ratio transmitted at one moment on the base layer controller, the optimization controller calculates the optimization wind-coal ratio in real time according to the preset optimization target, and corrects the calculated optimization wind-coal ratio according to the current heat value compensation quantity to obtain the finally output optimization wind-coal ratio, so that coal dust can be fully combusted through optimizing the wind-coal ratio, combustion efficiency is improved, and smoke exhaust loss is reduced.
Step 200: inputting the optimized wind-coal ratio calculated in real time into a base layer controller, and realizing combustion control of the circulating fluidized bed boiler by utilizing the base layer controller according to the optimized wind-coal ratio.
The basic layer controller is used for completing control of basic functions, and specifically comprises intelligent control of main steam pressure (load change), automatic control of main steam temperature, automatic control of drum liquid level, automatic control of wind-coal ratio and automatic control of hearth pressure, and is also a model-based predictive controller.
Specifically, step 200 includes the steps of:
A. setting a control target and inputting the optimized wind-coal ratio into the base layer controller.
The optimized control targets of the basic level controller comprise set control targets and optimized wind-coal ratios transmitted by the optimized controller, wherein the control targets comprise, but are not limited to, a drum liquid level control target, a main steam pressure control target, a main steam temperature control target and a hearth pressure control target.
B. And acquiring actual process parameters of the circulating fluidized bed boiler system, and correcting a model prediction output value according to the actual process parameters.
The actual process parameters include, but are not limited to, an actual drum liquid level value, an actual air-to-coal ratio, a main steam pressure value, a main steam temperature value and a furnace pressure value, and the corrected model prediction output values include, but are not limited to, a drum liquid level predicted value, an air-to-coal ratio predicted value, a main steam pressure predicted value, a main steam temperature predicted value and a furnace pressure predicted value. It is noted and understood that the actual process parameters described in this step B refer to the process parameters of the actual operation of the boiler at the previous time.
C. And comparing the corrected model prediction output value with a control target, and then inputting the difference value between the corrected model prediction output value and the control target into a basic-level dynamic solver of the basic-level controller to obtain the boiler combustion control quantity.
The boiler combustion control quantity comprises, but is not limited to, coal feeding quantity, primary air quantity, secondary air quantity, air intake quantity and water feeding quantity. The corrected model prediction output values and the control targets are respectively compared one by one, namely, the steam drum liquid level prediction value and the steam drum liquid level control target, the main steam pressure prediction value and the main steam pressure control target, the main steam temperature prediction value and the main steam temperature control target, the hearth pressure prediction value and the hearth pressure control target, the wind-coal ratio prediction value and the optimized wind-coal ratio are respectively compared, so that the difference value of the steam drum liquid level prediction value and the steam drum liquid level control target, the difference value of the main steam pressure prediction value and the main steam pressure control target, the difference value of the main steam temperature prediction value and the main steam temperature control target, the difference value of the hearth pressure prediction value and the hearth pressure control target and the difference value of the wind-coal ratio prediction value and the optimized wind-coal ratio are obtained, and are used as the corrected model prediction output values and the difference values of the main steam temperature control targets, and the hearth pressure prediction output values and the wind-coal ratio prediction values are all input into a basic-layer dynamic solver of a basic-layer controller, and the boiler combustion control quantity at the current moment is calculated by the basic-layer dynamic solver.
D. And conveying the boiler combustion control amount to the circulating fluidized bed boiler system so that the circulating fluidized bed boiler system can regulate and control the combustion of the circulating fluidized bed boiler according to the boiler combustion control amount.
The circulating fluidized bed boiler system is adjusted according to the boiler combustion control quantity at the current moment, so that long-period unmanned operation of the whole system is realized, optimal combustion of an online circulating fluidized bed boiler is realized, and the efficiency of the boiler is improved.
In summary, the present specification discloses a combustion control system of a circulating fluidized bed boiler and a method thereof, which adopts two layers of model-based predictive controllers, wherein the multivariable predictive control technology of the two layers of controllers can realize advanced pre-judgment and advanced adjustment of key variables, and can realize multivariable decoupling, and the base layer controller completes automatic control of basic functions, and the optimizing controller calculates the optimized wind-coal ratio on line in real time, so as to realize optimal combustion of the on-line circulating fluidized bed boiler, fully combust coal dust, improve the combustion efficiency of the boiler, and effectively realize long-period unmanned operation and energy saving and consumption reduction of the circulating fluidized bed boiler under normal production of the boiler.
Those of ordinary skill in the art will appreciate that: the drawing is a schematic diagram of one embodiment and the modules or flows in the drawing are not necessarily required to practice the invention.
Those of ordinary skill in the art will appreciate that: the modules in the apparatus of the embodiments may be distributed in the apparatus of the embodiments according to the description of the embodiments, or may be located in one or more apparatuses different from the present embodiments with corresponding changes. The modules of the above embodiments may be combined into one module, or may be further split into a plurality of sub-modules.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A circulating fluidized bed boiler combustion control system, comprising:
the optimizing controller is used for calculating the optimized wind-coal ratio in real time according to the actual wind-coal ratio and the preset optimizing target, correcting the calculated optimized wind-coal ratio according to the current heat value compensation quantity, and obtaining the finally output corrected optimized wind-coal ratio;
the base layer controller is connected with the optimizing controller and is used for realizing the optimized combustion control of the circulating fluidized bed boiler according to the corrected optimized wind-coal ratio output by the optimizing controller; the optimized target value of the base layer controller is the corrected optimized wind-coal ratio and a set control target;
wherein the optimization controller and the base layer controller are both model-based predictive controllers.
2. The circulating fluidized bed boiler combustion control system of claim 1, wherein the base layer controller comprises:
the feedback correction module is connected with the circulating fluidized bed boiler system and is used for collecting actual process parameters;
the model prediction module is connected with the feedback correction module and is used for correcting a model prediction output value according to the actual process parameter;
the output end of the basic layer dynamic solver is respectively connected with the model prediction module and the circulating fluidized bed boiler system, the input value of the basic layer dynamic solver is the difference value between the corrected model prediction output value and the control target, and the output value is the boiler combustion control quantity; the boiler combustion control quantity comprises coal feeding quantity, primary air quantity, secondary air quantity, air intake quantity and water feeding quantity.
3. The circulating fluidized bed boiler combustion control system of claim 2, wherein the actual process parameters comprise an actual drum level value, an actual wind-to-coal ratio, a main steam pressure value, a main steam temperature value, and a furnace pressure value, and the modified model predictive output values comprise a drum level predictive value, a wind-to-coal ratio predictive value, a main steam pressure predictive value, a main steam temperature predictive value, and a furnace pressure predictive value;
the control targets comprise a drum liquid level control target, a main steam pressure control target, a main steam temperature control target and a hearth pressure control target;
the input values of the basic layer dynamic solver are the difference value between the steam drum liquid level predicted value and the steam drum liquid level control target, the difference value between the main steam pressure predicted value and the main steam pressure control target, the difference value between the main steam temperature predicted value and the main steam temperature control target, the difference value between the hearth pressure predicted value and the hearth pressure control target and the difference value between the wind-coal ratio predicted value and the optimized wind-coal ratio.
4. A combustion control method of a circulating fluidized bed boiler, comprising:
setting a preset optimization target; the preset optimization targets comprise oxygen content and ton coal steam production;
inputting the heat value compensation quantity and the actual wind-coal ratio into an optimization controller, calculating an output wind-coal ratio in real time by the optimization controller according to the preset optimization target, and correcting the output wind-coal ratio according to the heat value compensation quantity to obtain an optimized wind-coal ratio;
inputting the optimized wind-coal ratio calculated in real time into a base layer controller, and realizing combustion control of the circulating fluidized bed boiler by utilizing the base layer controller according to the optimized wind-coal ratio; wherein the optimization controller and the base layer controller are both model-based predictive controllers.
5. The combustion control method of a circulating fluidized bed boiler according to claim 4, wherein the inputting the optimized wind-coal ratio calculated in real time into a base layer controller, and the realizing combustion control of the circulating fluidized bed boiler by using the base layer controller according to the optimized wind-coal ratio specifically comprises:
setting a control target, and inputting the optimized wind-coal ratio into a base layer controller;
collecting actual process parameters of a circulating fluidized bed boiler system, and correcting a model prediction output value according to the actual process parameters;
comparing the corrected model prediction output value with the control target, and then inputting the difference value between the corrected model prediction output value and the control target into a basic-level dynamic solver of the basic-level controller to obtain the boiler combustion control quantity; the boiler combustion control quantity comprises coal supply quantity, primary air quantity, secondary air quantity, air intake quantity and water supply quantity;
and conveying the boiler combustion control quantity to the circulating fluidized bed boiler system so that the circulating fluidized bed boiler system can regulate and control the combustion of the circulating fluidized bed boiler according to the boiler combustion control quantity.
6. The method according to claim 5, wherein the actual process parameters include an actual drum level value, an actual wind-to-coal ratio, a main steam pressure value, a main steam temperature value, and a furnace pressure value, and the modified model predictive output values include a drum level predictive value, a wind-to-coal ratio predictive value, a main steam pressure predictive value, a main steam temperature predictive value, and a furnace pressure predictive value; the control targets comprise a drum liquid level control target, a main steam pressure control target, a main steam temperature control target and a hearth pressure control target;
comparing the corrected model predictive output value with the control target specifically includes:
and comparing the steam drum liquid level predicted value with the steam drum liquid level control target, the main steam pressure predicted value with the main steam pressure control target, the main steam temperature predicted value with the main steam temperature control target, the hearth pressure predicted value with the hearth pressure control target, the wind-coal ratio predicted value with the optimized wind-coal ratio respectively to obtain a difference value of the steam drum liquid level predicted value with the steam drum liquid level control target, a difference value of the main steam pressure predicted value with the main steam pressure control target, a difference value of the main steam temperature predicted value with the main steam temperature control target, a difference value of the hearth pressure predicted value with the hearth pressure control target and a difference value of the wind-coal ratio predicted value with the optimized wind-coal ratio.
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