Coal-fired boiler combustion optimization method and system suitable for deep peak regulation

Abstract

The invention provides a coal-fired boiler combustion optimization method and system suitable for deep peak regulation, and the method comprises the following steps: building a three-dimensional mathematical model of a coal-fired boiler, and carrying out the numerical simulation of the working conditions formed by the combination of different air distribution modes and coal distribution modes of the coal-fired boiler under each preset load, so as to obtain a model database; when the power grid is subjected to deep peak regulation, comparing the actual load of operation of the coal-fired boiler with each load in the database to obtain all preset loads which are the same as the actual load; all different air distribution modes and coal distribution modes under the load which is the same as the actual load are compared, and a comparison result of the CO2 mole fraction and the CO mole fraction at the flue gas outlet of the coal-fired boiler is obtained; and selecting an optimal air distribution mode and an optimal coal distribution mode in the comparison result. According to the method, the optimal coal and air distribution mode can be selected according to the load change during deep peak regulation of the coal-fired boiler so as to achieve combustion optimization.

Description

Technical Field

[0001] The present invention relates to the field of coal-fired boilers, and in particular to a method and system for optimizing combustion of coal-fired boilers suitable for deep peak regulation. Background Art

[0002] With the massive access of renewable energy to the power grid, the demand for power grid peak-shaving capacity is increasing. Traditional coal-fired power plants need to have rapid peak-shaving capabilities to adapt to rapid changes in power grid load. However, when existing coal-fired boilers are performing load regulation, the original air distribution method and coal distribution method are no longer the best combustion solution.

[0003] At present, the optimization of boiler combustion is mainly carried out by changing the air-coal ratio, burner angle, etc. The existing technology does not optimize the combustion during deep peak load regulation, and lacks the coal and air distribution methods that match the load changes.

[0004] Therefore, it is necessary to provide a new technical solution. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the present invention discloses a method and system for optimizing the combustion of a coal-fired boiler suitable for deep peak load regulation, which can select the optimal coal and air distribution mode according to load changes during deep peak load regulation of the coal-fired boiler to achieve combustion optimization. The specific technical solution is as follows:

[0006] In one aspect, the present invention provides a method for optimizing combustion of a coal-fired boiler suitable for deep peak load regulation, comprising the following steps:

[0007] A three-dimensional mathematical model of a coal-fired boiler is established, and a numerical simulation is performed on the operating conditions of the coal-fired boiler under each preset load under different air distribution modes and coal distribution modes to obtain a model database;

[0008] When the power grid is performing deep peak load regulation, the actual load of the coal-fired boiler operation is compared with each load in the database to obtain all preset loads that are the same as the actual load;

[0009] All different air distribution methods and coal distribution methods under the same load as the actual load are compared to obtain the comparison results of CO2 mole fraction and CO mole fraction at the flue gas outlet of the coal-fired boiler;

[0010] Select the optimal air distribution method and the optimal coal distribution method from the comparison results.

[0011] Furthermore, the coal-fired boiler has five layers of burners, and each layer of burners corresponds to a coal blending method.

[0012] Furthermore, the air distribution methods include upright pagoda air distribution, inverted pagoda air distribution, waist-shrinking air distribution and equal air distribution;

[0013] The coal blending method includes high-quality coal, general coal and low-quality coal.

[0014] Furthermore, the optimal air distribution method and the optimal coal distribution method are the highest CO2 mole fraction and the lowest CO mole fraction.

[0015] Furthermore, the optimal air distribution mode for the five-layer burner is equal air distribution;

[0016] The optimal coal blending method for the five-layer burner is high-quality coal, general coal, low-quality coal, low-quality coal and low-quality coal.

[0017] On the other hand, the present invention also provides a coal-fired boiler combustion optimization system suitable for deep peak regulation, which includes a model building module, a data acquisition module, a comparison module, a result selection module and a coal-fired boiler.

[0018] The model building module is used to build a three-dimensional mathematical model of a coal-fired boiler, and to numerically simulate the working conditions formed by the combination of different air distribution modes and coal distribution modes of the coal-fired boiler under each preset load to obtain a model database;

[0019] The data acquisition module is used to obtain the actual load of the coal-fired boiler in real time;

[0020] The comparison module is used to compare the actual load of the coal-fired boiler with each load in the database when the power grid performs deep peak regulation, and obtain all preset loads that are the same as the actual load;

[0021] The comparison module is also used to compare all different air distribution methods and coal distribution methods under the same assumed load as the actual load, and obtain the comparison result of the CO2 mole fraction and the CO mole fraction at the flue gas outlet of the coal-fired boiler;

[0022] The result selection module is used to select the optimal air distribution method and the optimal coal distribution method in the comparison results.

[0023] The present invention has the following beneficial effects:

[0024] The present invention provides a combustion optimization method for a coal-fired boiler suitable for deep peak regulation. The method uses an established model database to provide the best coal and air distribution scheme for boiler combustion according to the load during deep peak regulation to achieve combustion optimization.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 The present invention is a flowchart of the combustion optimization method of a coal-fired boiler suitable for deep peak regulation. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0029] The invention discloses a method for optimizing combustion of a coal-fired boiler suitable for deep peak regulation. The key point of the method is to establish a model database for the operating conditions formed by the combination of different air distribution modes and coal distribution modes under each load; to find all the models matching the operating conditions in the database according to the operating conditions during deep peak regulation; to obtain the optimal operating conditions of boiler combustion and a combustion optimization plan by comparing the simulation results of all the models.

[0030] See also Figure 1 The coal-fired boiler combustion optimization method suitable for deep peak regulation of the present invention comprises the following steps:

[0031] S1. Establish a three-dimensional mathematical model of a coal-fired boiler, and perform numerical simulation on the working conditions formed by the combination of different air distribution methods and coal distribution methods under each preset load to obtain a model database. In this step, the model database includes multiple preset loads, and each preset load includes a combination of multiple air distribution methods and coal distribution methods. Among them, the coal-fired boiler is a five-layer burner, and each layer of burners corresponds to a coal distribution method. The air distribution methods include positive pagoda air distribution, inverted pagoda air distribution, waisted air distribution and equal air distribution; the coal distribution methods include high-quality coal, general coal and low-quality coal.

[0032] S2. When the power grid performs deep peak regulation, the controller will compare the actual load of the coal-fired boiler with each load in the database according to the peak regulation demand of the power grid, and obtain all preset loads that are the same as the actual load. The following example describes this step. For example, if the actual load of the coal-fired boiler is 296MW, the operating conditions that are the same as the actual load of the coal-fired boiler are matched in the model database, as shown in Table 1 below, where the sequence number shows all preset loads in the model database that are the same as the actual load of 296MW obtained after comparison.

[0033] Table 1

[0034]

[0035] S3. Compare all different air distribution methods and coal distribution methods under the same preset load as the actual load to obtain the comparison results of the CO2 mole fraction and the CO mole fraction at the flue gas outlet of the coal-fired boiler, as shown in Table 2. In this step, each air distribution method and coal distribution method under the preset load corresponds to a combustion result, that is, the CO2 mole fraction and the CO mole fraction at the flue gas outlet of the coal-fired boiler, and the different combustion results are compared.

[0036] Table 2

[0037]

[0038]

[0039] S4. Select the optimal air distribution method and the optimal coal distribution method in the comparison results according to the mole fraction of CO2 and the mole fraction of CO, among which the optimal air distribution method and the optimal coal distribution method are the ones with the highest mole fraction of CO2 and the lowest mole fraction of CO. Because CO2 is the product of complete combustion of fuel, a higher mole fraction of CO2 usually indicates more complete combustion, while CO is a sign of incomplete combustion. A high mole fraction of CO may mean low combustion efficiency, which may lead to energy waste and emission of harmful gases. As shown in Table 1 above, all the working conditions of different coal and air distribution schemes when the preset load is 296MW are compared. It is found that when the load is 296MW, the air distribution mode is equal, that is, the air volume of each burner is uniform. When the coal distribution of the five-layer burner is high-quality coal, general coal, inferior coal, inferior coal, and inferior coal, the CO2 mole fraction is the highest and the CO mole fraction is the lowest, indicating that the combustion of the boiler is the best under this working condition. Under this working condition, the distance between the primary and secondary air ports is relatively small, and the primary and secondary air ports can be quickly mixed after flowing out from the nozzle, so that the coal powder airflow will not affect the combustion due to the air not being able to keep up after ignition. The uniform distribution of heat load in the furnace is conducive to the complete combustion of coal powder. At the same time, the lower burner uses high-quality coal, which burns fully and releases a lot of heat, providing sufficient heat source and stable high-temperature environment for the initial combustion of the boiler; the middle and upper burners use general coal and inferior coal, and the combustion characteristics of these coals are poor. The high temperature conditions provided by the lower burner can improve their combustion efficiency.

[0040] In another embodiment, the present invention also provides a coal-fired boiler combustion optimization system suitable for deep peak regulation, which includes a model building module, a data acquisition module, a comparison module, a result selection module and a coal-fired boiler, and the model building module, data acquisition module, comparison module, result selection module and coal-fired boiler are communicatively connected.

[0041] The model building module is used to build a three-dimensional mathematical model of a coal-fired boiler, and to numerically simulate the operating conditions formed by the combination of different air distribution modes and coal distribution modes of the coal-fired boiler under each preset load to obtain a model database.

[0042] The data acquisition module is used to acquire the actual load of the coal-fired boiler in real time.

[0043] The comparison module is used to compare the actual load of the coal-fired boiler with each load in the database when the power grid performs deep peak regulation, and obtain all preset loads that are the same as the actual load.

[0044] The comparison module is also used to compare all different air distribution methods and coal distribution methods under the same assumed load as the actual load, and obtain the comparison result of the CO2 mole fraction and the CO mole fraction at the flue gas outlet of the coal-fired boiler.

[0045] The result selection module is used to select the optimal air distribution method and the optimal coal distribution method.

[0046] Compared with the prior art, the present invention uses an established model database to provide the best coal and air distribution plan for boiler combustion according to the load during deep peak regulation, thereby achieving combustion optimization.

[0047] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0048] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify and vary the above embodiments within the scope of the present invention.

Claims

1. A method for optimizing combustion of a coal-fired boiler suitable for deep peak load regulation, characterized in that: It includes the following steps: A three-dimensional mathematical model of a coal-fired boiler is established, and a numerical simulation is performed on the operating conditions of the coal-fired boiler under each preset load under different air distribution modes and coal distribution modes to obtain a model database; When the power grid is performing deep peak load regulation, the actual load of the coal-fired boiler operation is compared with each load in the database to obtain all preset loads that are the same as the actual load; All different air distribution methods and coal distribution methods under the same load as the actual load are compared to obtain the comparison results of CO2 mole fraction and CO mole fraction at the flue gas outlet of the coal-fired boiler; Select the optimal air distribution method and the optimal coal distribution method from the comparison results.

2. The method for optimizing the combustion of a coal-fired boiler suitable for deep peak load regulation according to claim 1, characterized in that: The coal-fired boiler has five layers of burners, and each layer of burners corresponds to a coal distribution method.

3. The method for optimizing combustion of a coal-fired boiler suitable for deep peak load regulation according to claim 2, characterized in that: The air distribution methods include upright pagoda air distribution, inverted pagoda air distribution, waist-shrinking air distribution and equal air distribution; The coal blending method includes high-quality coal, general coal and low-quality coal.

4. The method for optimizing combustion of a coal-fired boiler suitable for deep peak load regulation according to claim 3, characterized in that: The optimal air distribution method and the optimal coal distribution method are the ones with the highest CO2 mole fraction and the lowest CO mole fraction.

5. The method for optimizing combustion of a coal-fired boiler suitable for deep peak load regulation according to claim 4, characterized in that: The optimal air distribution method for a five-layer burner is equal air distribution; The optimal coal blending method for the five-layer burner is high-quality coal, general coal, low-quality coal, low-quality coal and low-quality coal.

6. A coal-fired boiler combustion optimization system suitable for deep peak load regulation, characterized in that: It includes model building module, data acquisition module, comparison module, result selection module and coal-fired boiler. The model building module is used to build a three-dimensional mathematical model of a coal-fired boiler, and to numerically simulate the working conditions formed by the combination of different air distribution modes and coal distribution modes of the coal-fired boiler under each preset load to obtain a model database; The data acquisition module is used to obtain the actual load of the coal-fired boiler in real time; The comparison module is used to compare the actual load of the coal-fired boiler with each load in the database when the power grid performs deep peak regulation, and obtain all preset loads that are the same as the actual load; The comparison module is also used to compare all different air distribution methods and coal distribution methods under the same assumed load as the actual load, and obtain the comparison result of the CO2 mole fraction and the CO mole fraction at the flue gas outlet of the coal-fired boiler; The result selection module is used to select the optimal air distribution method and the optimal coal distribution method in the comparison results.

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