CN113050711A - Coordinated control method for internal and external desulfurization systems of circulating fluidized bed boiler - Google Patents
Coordinated control method for internal and external desulfurization systems of circulating fluidized bed boiler Download PDFInfo
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- CN113050711A CN113050711A CN202110316640.3A CN202110316640A CN113050711A CN 113050711 A CN113050711 A CN 113050711A CN 202110316640 A CN202110316640 A CN 202110316640A CN 113050711 A CN113050711 A CN 113050711A
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- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D11/00—Control of flow ratio
- G05D11/02—Controlling ratio of two or more flows of fluid or fluent material
- G05D11/13—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means
- G05D11/131—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means by measuring the values related to the quantity of the individual components
- G05D11/132—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means by measuring the values related to the quantity of the individual components by controlling the flow of the individual components
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Abstract
The invention relates to the technical field of energy conservation and environmental protection of industrial thermal combustion devices, and discloses a method for controlling the coordination of an internal and external desulfurization system of a circulating fluidized bed boiler, which comprises the following steps: (1) the device is provided with an external desulfurization control point optimization model and an internal desulfurization control point optimization model. (2) The optimization model of the external desulfurization control point refers to the number of minutes M according to the current time and the current chimney inlet SO2The hourly mean value and the target value Plwsp for the hourly mean value, real-time prediction that the current stack inlet SO is such that at the end of the hourly period the hourly mean value P0 is equal to the target of the basic control point Plwsp2The instantaneous concentration value control point P should be set to what. (3) The model is optimized by the control points in the furnace, SO that the environmental protection index is not over standard, and the SO is increased2Concentration hourly mean.
Description
Technical Field
The invention relates to the technical field of energy conservation and environmental protection of industrial thermal combustion devices, in particular to a control method for coordination of an internal and external desulfurization system of a circulating fluidized bed boiler.
Background
China is a country with coal as a main energy source, coal-fired power generation is one of the most important ways for coal utilization in China, and SO is among a plurality of atmospheric pollutants discharged by coal-fired thermal power generating units2And dust is a major pollutant to control, which is a major environmental hazard. With the progress of society and the development of economy, the pollution of thermal power plants to the atmospheric environment has received general attention of peopleTherefore, effectively reducing the pollutant emission to improve the influence on the environment is a serious challenge for sustainable development in the energy field of China. Currently, technologies for controlling coal pollution include desulfurization before combustion of coal, desulfurization during combustion, and desulfurization of flue gas after combustion.
There are various existing techniques for controlling desulfurization. Wherein, Xinjiang Bingjiu agriculture-Ochi Tianshan aluminum industry Co Ltd discloses a patent of 'a control method for desulfurization by semidry method' (application number: CN 201510913014.7), specifically, a main PID is used to set a desulfurization outlet SO2Concentration and desulfurization outlet on-line measurement SO2Controlling the feeding amount of slaked lime of the variable-frequency screw feeder according to the concentration deviation PI operation result; auxiliary PID online measurement SO with desulfurization inlet2First-order inertia of concentration and online measurement of SO at desulfurization inlet2And the concentration deviation PI operation result is used as a main PID feedforward signal. But it does not relate to the desulfurization outlet SO2Concentration set value and online measurement of SO at desulfurization inlet2The concentration is optimized, and the desulfurizer cannot be effectively saved when the precision is low due to fluctuation of the combustion working condition. The university of North China electric Power discloses an invention patent 'an optimized control method for in-furnace desulfurization of a circulating fluidized bed' (application number: CN 201510041408.8), specifically interacting data with DCS through a related communication mode, and establishing SO2The prediction model and the coal sulfur self-adaptive correction method can dynamically adjust the feeding amount of limestone in time to control SO2The purpose within the index. However, because the desulfurization efficiency in the boiler is greatly influenced by the fluctuation of the pressure of a boiler bed, the primary air quantity, the secondary air quantity and the load of the boiler, the higher combustion efficiency of the boiler is usually sacrificed when the desulfurization efficiency is pursued, and the comprehensive energy consumption is increased.
In summary, each desulfurization control technique has different processes and can effectively reduce SO2However, in many thermal power plants, two sets of control systems for desulfurization during combustion and flue gas desulfurization after combustion are independent of each other, the workload of manual operation is large, and coordination control cannot be effectively performed, so that the problems of waste of the desulfurizer, excessive environmental protection and the like are easily caused.
Disclosure of Invention
In view of the above problems, the present invention provides a method for coordinating and controlling a desulfurization system inside and outside a circulating fluidized bed boiler, wherein the desulfurization system is arranged at the outlet SO of a final chimney2On the premise that the concentration is controlled within the index range, the output of the desulfurization inside and outside the furnace is coordinated, and the economic operation is achieved.
The invention adopts the following technical scheme for solving the technical problems:
a coordinated control method for a furnace and external desulfurization system of a circulating fluidized bed boiler comprises the following steps: (1) an external desulfurization control point optimization model and an internal desulfurization control point optimization model are arranged; (2) the optimization model of the external desulfurization control point refers to the number of minutes M according to the current time and the current chimney inlet SO2The hourly mean value and the target value Plwsp for the hourly mean value, real-time prediction that the current stack inlet SO is such that at the end of the hourly period the hourly mean value P0 is equal to the target of the basic control point Plwsp2What the instantaneous concentration value control point P should be set to; (3) the model is optimized by the control points in the furnace, SO that the environmental protection index is not over standard, and the SO is increased2Concentration hourly mean.
The in-furnace control point optimization model in the step (1) is characterized in that when working condition fluctuation such as large load increase of a boiler, large increase of sulfur content of coal as fired, unsmooth feeding of an external feeding execution mechanism and the like and capacity of an external desulfurization system are limited, SO at a chimney inlet is used as a chimney2The instantaneous value of the concentration will rise rapidly, if this occurs in the middle and later hours of the hour period, SO2The small-hour average concentration value is extremely easy to exceed the standard. At the moment, the desulfurization control point in the furnace needs to be lowered in real time to increase the desulfurization output in the furnace.
According to the in-furnace control point optimization model in the step (1), when working condition fluctuation such as great load reduction of a boiler, great reduction of sulfur content of coal as fired and the like occurs, due to the characteristics of the process of the out-furnace desulfurization system, the out-furnace desulfurization agent is in an excessive state after the working condition fluctuation occurs, and at the moment, if the working condition fluctuation does not occur in time, the output of the in-furnace desulfurization system is reduced to increase the SO output of an air preheater outlet2Concentration, even if the external feeding actuator does not feed for a long time, the chimney inlet SO2The concentration will also remain low for a long period of time and the hourly mean is difficult to increase.
The invention relates to a coordinated control method for a furnace and external desulfurization system of a circulating fluidized bed boiler, which adopts the technical scheme and has the following advantages: 1. by correcting the external desulfurization control point, SO, in real time2The hour average value can be controlled to be close to the upper limit of environmental protection, and the aim of saving the desulfurizer is fulfilled. 2. By predicting the possibility that the hour average value exceeds the standard, the desulfurization control point in the furnace is corrected in real time, so that the environmental protection index still does not exceed the standard even if the working condition has large fluctuation, and the aim of saving the desulfurizing agent in the furnace can be fulfilled when the desulfurization capacity outside the furnace is predicted to be strong.
Drawings
FIG. 1 is a flow chart of the coordinated control method of the desulfurization system inside and outside the furnace according to the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
As shown in the attached drawing, the invention is a flow chart of the coordination control method of the furnace and external desulfurization system, which comprises an external desulfurization control point optimization model and a furnace control point optimization model.
An optimization model of the external desulfurization control point is adopted according to the number of minutes M of the current time and the current chimney inlet SO2An hour mean value P0 and a basic control point Plwsp (an hour mean value target value is generally set to a value 10-20 mg/Nm3 smaller than an environmental index), and a chimney inlet SO capable of satisfying the hour mean value target value Psp is corrected in real time2The instantaneous concentration value control point P. Specific P = (60Plwsp-P0 × M)/(60-M).
An in-furnace control point optimization model, when the desulfurizing agent of the out-of-furnace desulfurizing system is excessive or the desulfurizing capacity is limited, according to the current time and minutes M and the current chimney inlet SO2Hourly mean value P0 and stack inlet SO2Instantaneous value of concentration Ppv, estimate SO at the end of the hour period2The possibility that the hour average value exceeds the basic control point Plowp requires real-time adjustment of the desulfurization control point in the furnace to adjust the desulfurization output in the furnace. Specifically, the possibility KN was evaluated, KN = M × P0/60 × Plwsp was defined, and the calculated KN value was divided into N intervals, (X1, X2), (X2, X3) … (Xn-2, Xn-1), and the corresponding furnaceThe correction amount of the inner control point is Y1, Y2 … Yn, i.e. when the value of KN is in different intervals, Q = Plwsp + Y [1 … n ]]. It can be seen that when KN>1, SO at the end of the hour period2The hour average will certainly exceed the basic control point Plwsp. In general, KN<When the value is 0.5, the value range of Y is-1000-0; KN>When the value is 0.5, the value range of Y is 0-1000.
Claims (4)
1. A coordinated control method for a furnace and an external desulfurization system of a circulating fluidized bed boiler is characterized by comprising the following steps: an external desulfurization control point optimization model and an internal desulfurization control point optimization model are established outside independent internal and external desulfurization controllers.
2. The method of claim 1, wherein the model for optimizing the desulfurization control points outside the furnace is based on the number of minutes of the current time and the current chimney inlet SO2The hourly mean value and the target value of the hourly mean value are used for adjusting the SO at the inlet of the chimney in real time2Instantaneous value of concentration control point to make SO2The hourly mean concentration reached the target value.
3. The method of claim 1, wherein the in-furnace desulfurization control point optimization model is configured to reduce the in-furnace desulfurization control point in real time to increase the in-furnace desulfurization output and avoid SO output when the capacity of the out-furnace desulfurization system is limited due to fluctuations in operating conditions such as a large increase in load on the boiler, a large increase in sulfur content of the coal as fired, and poor feeding of an out-furnace feed actuator2The average value exceeds the standard when the concentration is small.
4. The coordinated control method for the furnace and external desulfurization system of the circulating fluidized bed boiler as claimed in claim 1, wherein SO is established2Evaluating the possibility of exceeding the average value in small concentration hour, and predicting SO in real time2When the concentration is small, the possibility that the average value exceeds the standard is adjusted in real time according to the evaluation index, and when the concentration appears like a boilerThe furnace greatly reduces the load, the sulfur content of the coal as fired is greatly reduced, and other working condition fluctuations, and the output of the desulfurization system in the furnace is timely reduced to increase the SO at the outlet of the air preheater2The concentration can achieve the purpose of saving the desulfurizer in the furnace while ensuring that the environmental protection index does not exceed the standard.
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| CN202110316640.3A CN113050711A (en) | 2021-03-24 | 2021-03-24 | Coordinated control method for internal and external desulfurization systems of circulating fluidized bed boiler |
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Citations (5)
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| CN1289631A (en) * | 2000-10-18 | 2001-04-04 | 鞍山西玛环保有限公司 | Fuzzy control method for desulfurizing boiler by spraying sulfur fixating agent |
| CN104615114A (en) * | 2015-01-27 | 2015-05-13 | 华北电力大学 | Furnace desulphurization optimization control method for circulating fluidized bed |
| CN105116855A (en) * | 2015-07-22 | 2015-12-02 | 华北电力大学 | Optimal control method for flue gas circulating fluidized bed desulphurization |
| CN105536488A (en) * | 2015-12-11 | 2016-05-04 | 新疆生产建设兵团农八师天山铝业有限公司 | Control method for SO2 during semi-dry desulfurization |
| CN207951100U (en) * | 2017-11-23 | 2018-10-12 | 北京中煤神州节能环保技术开发有限公司 | Properties of CFB kiln gas discharges running optimizatin cost calculating system |
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2021
- 2021-03-24 CN CN202110316640.3A patent/CN113050711A/en active Pending
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| CN1289631A (en) * | 2000-10-18 | 2001-04-04 | 鞍山西玛环保有限公司 | Fuzzy control method for desulfurizing boiler by spraying sulfur fixating agent |
| CN104615114A (en) * | 2015-01-27 | 2015-05-13 | 华北电力大学 | Furnace desulphurization optimization control method for circulating fluidized bed |
| CN105116855A (en) * | 2015-07-22 | 2015-12-02 | 华北电力大学 | Optimal control method for flue gas circulating fluidized bed desulphurization |
| CN105536488A (en) * | 2015-12-11 | 2016-05-04 | 新疆生产建设兵团农八师天山铝业有限公司 | Control method for SO2 during semi-dry desulfurization |
| CN207951100U (en) * | 2017-11-23 | 2018-10-12 | 北京中煤神州节能环保技术开发有限公司 | Properties of CFB kiln gas discharges running optimizatin cost calculating system |
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Application publication date: 20210629 |