System for blending combustion of biomass briquette in thermal power plant and control method

Abstract

The invention provides a system for blending combustion of biomass briquette fuel in a thermal power plant and a control method, the system comprises independent transportation, sampling, storage and conveying modules of biomass and coal, fuel types are automatically distinguished through an identification device above a coal conveying belt, and the fuel types are respectively conveyed to a biomass sub-bin or a raw coal sub-bin. The coal mill switches fuel sources according to unit loads, biomass is combusted in the low load, coal is switched in the high load, the air temperature and the air-coal ratio are adjusted through a primary air valve, and the combustion efficiency is optimized. The control method comprises fuel identification, metering bin separation, load self-adaptive switching and air temperature cooperative adjustment, it is ensured that the mass of biomass entering the furnace is accurately metered, and meanwhile the investment cost is reduced through existing equipment of a power plant. The system solves the problems of inaccurate metering and inflexible switching in biomass blending combustion, has economical efficiency and environmental protection benefits, and is suitable for peak regulation and low-carbon transformation of a thermal power plant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomass blending combustion, in particular to a system and control method for blending combustion of biomass briquettes in a thermal power plant. BACKGROUND

[0002] Blending combustion of biomass fuel in large high-efficiency coal-fired units for power generation is an advanced technology for efficient utilization of biomass, which can significantly improve the efficiency of biomass power generation, save biomass resources, significantly reduce carbon emissions of coal-fired units, improve the flexibility of coal and biomass coupled power generation, and thus strengthen the sustainability of coal-fired power generation, which is a realistic and feasible path for coal-fired power generation to be low-carbon.

[0003] Biomass bulk material has high moisture content, low calorific value and small density, and is not easy to transport and store. When blended in a power plant, a special storage yard and crushing equipment need to be newly built, and the crushing particle size cannot meet the requirements of a coal-fired boiler. It is generally suitable for small-scale biomass direct-fired power plants. In large coal-fired boilers, a large proportion of biomass should be considered for blending combustion of biomass briquettes. The main chemical components of existing biomass briquettes are lignin, cellulose and hemicellulose. The higher the lignin content, the greater the crushing strength, and the greater the fiber aspect ratio, the more likely it is to stick to the shaft. The grinding effect of the coal mill on biomass briquettes is poor. When biomass briquettes are mixed with coal for pulverization, the output of the coal mill will be significantly affected. In addition, biomass briquettes have low calorific value, so blending combustion of biomass briquettes will affect the load carrying capacity of the unit. On the other hand, when biomass briquettes are mixed with coal and fed into the boiler for combustion, the amount of biomass fed into the furnace is difficult to measure, which affects the calculation of coal consumption and carbon emissions of the unit. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a system and control method for blending combustion of biomass briquettes in a thermal power plant, which fully utilizes the existing equipment in the power plant to independently spray and blend combustion of biomass briquettes, has the advantages of small investment, flexible switching of coal / biomass fuel, accurate measurement of the amount of biomass fed into the furnace, and auxiliary boiler peak shaving.

[0005] The present application is achieved by the following technical solutions: A control method for blending combustion of biomass briquettes in a thermal power plant, comprising the following steps: identifying the type of fuel on the coal conveying belt by a recognition device; if the fuel is biomass briquettes, starting the A-side belt and closing the B-side belt, and stopping the operation of the sampling machine; if the fuel is coal, starting the B-side belt and closing the A-side belt, and starting the operation of the sampling machine; The belt scale is used to measure the weight of fuel in real time, and the data is recorded in the biomass module or the coal module respectively. The fuel is stored in the biomass bunker or the raw coal bunker after being sorted. According to the unit load instruction, the biomass briquette and the coal are switched for entering the furnace. When the load instruction is higher than 75%THA, the outlet of the biomass bunker is closed and the outlet of the raw coal bunker is opened. When the load instruction is lower than 75%THA, the outlet of the raw coal bunker is closed and the outlet of the biomass bunker is opened. Preferably, the image recognition algorithm based on random forest is used to judge the fuel type on the coal conveying belt through the recognition device, specifically: S1, the recognition device continuously or periodically captures the fuel image being conveyed on the coal conveying belt; S2, the fuel image is preprocessed by denoising, graying and normalizing; S3, the random forest algorithm is used to extract features and classify the collected images from the preprocessed fuel images; S4, the random forest model is trained by constructing a sample image dataset from the extracted features; S5, the trained random forest model is used for fuel type recognition, and the recognition result of the fuel type is output.

[0006] Preferably, when the load instruction is higher than 75%THA, the following operations are performed synchronously: The primary air valve opening is reduced to reduce the air-coal ratio. The cold primary air valve opening is reduced and the hot primary air valve opening is increased to increase the mill inlet air temperature.

[0007] Preferably, when the load instruction is lower than 75%THA, the following operations are performed synchronously: The primary air valve opening is increased to increase the air-coal ratio. The cold primary air valve opening is increased and the hot primary air valve opening is reduced to reduce the mill inlet air temperature.

[0008] Preferably, according to the unit load instruction, the biomass briquette and the coal are switched for entering the furnace. Specifically, when the unit is in low load, the outlet of the raw coal bunker is closed, the biomass briquette in the biomass bunker enters the coal mill for pulverizing, and then is carried by the primary air into the pulverized coal burner for combustion, and the generated heat enters the boiler. When the boiler is in high load, the outlet of the biomass bunker is closed, and the coal in the raw coal bunker enters the coal mill for pulverizing, and then is carried by the primary air into the pulverized coal burner for combustion, and the generated heat enters the boiler.

[0009] A system for blending biomass briquettes in a thermal power plant, comprising, a fuel conveying and storage unit, a fuel recognition and sorting unit, and a combustion control unit; The fuel identification and metering unit comprises a coal conveying belt, a belt scale, a sampling machine, an A-side belt, a B-side belt, a biomass bunker and a raw coal bunker, The coal conveying belt is provided with an identification device for identifying the type of fuel transported on the coal conveying belt; the belt scale is arranged at the rear end of the coal conveying belt and is used for weighing the weight of the fuel transported on the coal conveying belt; and the sampling machine is used for automatically sampling the coal. The A-side belt and the B-side belt are respectively arranged at the rear end of the coal conveying belt, the A-side belt is connected with the biomass bunker, and the B-side belt is connected with the raw coal bunker; the front end of the coal conveying belt is connected with the fuel conveying and storage unit; and the biomass bunker and the raw coal bunker are connected with the combustion control unit.

[0010] Preferably, the fuel conveying and storage unit comprises a biomass briquette conveying vehicle, a coal conveying vehicle and a coal shed; and the coal shed is connected with the front end of the coal conveying belt.

[0011] Preferably, the coal shed is divided into a plurality of independent storage areas for temporarily storing the biomass briquettes and the coal sampled by the biomass and coal sampling devices.

[0012] Preferably, the combustion control unit comprises a coal mill, a primary air valve, a hot primary air valve, a cold primary air valve, a pulverized coal burner, a boiler, a primary air fan and an air preheater. The discharge outlets of the biomass bunker and the raw coal bunker are connected with the inlet of the coal mill, the outlet of the coal mill is connected to the boiler through the pulverized coal burner, and the outlet of the primary air fan is divided into two paths, one of which is connected to the hot primary air valve through the air preheater, and the other is connected to the cold primary air valve, and the outlets of the hot primary air valve and the cold primary air valve are combined and then connected to the coal mill through the primary air valve.

[0013] Preferably, the identification device is a visual identification sensor for distinguishing the biomass briquettes and the coal.

[0014] Preferably, a random forest-based image recognition algorithm is used to identify the type of fuel.

[0015] Preferably, the biomass bunker and the raw coal bunker are independently sealed structures, and the discharge outlets are respectively provided with electric gate valves.

[0016] Compared with the prior art, the present application has the following beneficial technical effects: The present application provides a biomass briquette storage system in a coal shed, a biomass briquette conveying belt, a biomass briquette milling device and a biomass briquette combustion device, which can fully utilize the existing equipment of a power plant to blend and burn biomass briquettes, thereby reducing the investment and simplifying the system. ​

[0017] When the biomass briquette is mixed with coal by the way of coupling with the coal mill, the metering of the biomass quantity into the furnace is a difficult problem. The present application provides a method for accurately judging the fuel type on the coal conveying belt by using a recognition device and an image recognition algorithm based on random forest, and then controlling the working mode of the belt scale and the sampling machine to realize the accurate metering of the biomass quantity into the furnace, which meets the relevant regulations of coal consumption calculation and carbon emission verification.

[0018] The biomass fuel has high volatile matter and cannot be stored together with the coal powder. In the prior art, the raw coal bunker needs to be burned empty before the fuel is switched, and the rapid switching of the coal and the biomass briquette cannot be realized. The present application provides a method for separating the raw coal bunker into two sub-bunkers, i.e., a biomass sub-bunker and a raw coal sub-bunker, storing the biomass briquette in the biomass sub-bunker, storing the coal in the raw coal sub-bunker, and controlling the opening and closing of the discharge openings of the two sub-bunkers according to the unit load instruction, so as to realize the rapid switching of the biomass briquette and the coal powder into the furnace.

[0019] The present application provides a method for switching the biomass briquette and the coal powder into the furnace according to the unit load instruction. The coal powder is put in when the unit load is high, and the high calorific value of the coal powder is used to reach the peak. The biomass briquette is put in when the unit load is low, and the high volatile matter of the biomass is used to realize the stable combustion of the boiler at low load. Through the switching of the biomass briquette and the coal powder into the furnace, the unit load is improved while the peak capacity of the boiler is ensured, and the carbon emission level of the unit is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0021] Figure 1 The present application provides a system flow chart of the biomass briquette mixed with coal in a thermal power plant. In the drawings: 1. Biomass briquette transport vehicle; 2. Biomass sampling device into the plant; 3. Coal transport vehicle; 4. Coal sampling device into the plant; 5. Coal shed; 6. Coal conveying belt; 7. Recognition device; 8. Belt scale; 9. Sampling machine; 10. A-side belt; 11. B-side belt; 12. Biomass sub-bunker; 13. Raw coal sub-bunker; 14. Coal mill; 15. Primary air valve; 16. Hot primary air valve; 17. Cold primary air valve; 18. Coal powder burner; 19. Boiler; 20. Primary air fan; 21. Air preheater.

[0022] Figure 2The application discloses a control method for biomass briquette fuel blending combustion in a thermal power plant. Figure 3 The application discloses a control method for biomass briquette fuel blending combustion in a thermal power plant.

[0023] Figure 4 The application discloses a control method for biomass briquette fuel blending combustion in a thermal power plant. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the drawings of the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0025] To achieve the above object, the present application provides the following technical scheme: a system for biomass briquette fuel blending combustion in a thermal power plant, comprising a biomass briquette fuel transport vehicle 1, a biomass plant entry sampling device 2, a coal transport vehicle 3, a coal plant entry sampling device 4, a coal shed 5, a coal conveying belt 6, a recognition device 7, a belt scale 8, a sampling machine 9, an A-side belt 10, a B-side belt 11, a biomass warehouse 12, a raw coal warehouse 13, a coal mill 14, a primary air valve 15, a hot primary air valve 16, a cold primary air valve 17, a pulverized coal burner 18, a boiler 19, a primary air fan 20 and an air preheater 21. The specific process is that the biomass briquette fuel is transported to the power plant by the biomass briquette fuel transport vehicle 1, then automatically sampled and sent for inspection by the biomass plant entry sampling device 2, and the calorific value and moisture content are tested. The biomass briquette fuel transport vehicle after sampling enters the coal shed 5 to unload, and the biomass briquette fuel is temporarily stored in the coal shed 5. The coal is transported to the plant by the coal transport vehicle 2, then automatically sampled by the coal plant entry sampling device 4, and then unloaded in the coal shed 5, and the coal is temporarily stored in the coal shed 5. The biomass briquette fuel and the coal are independently stored in different areas in the coal shed 5.

[0026] The biomass briquette or coal in the coal shed first enters the coal conveying belt 6, and an identification device 7 is arranged on the upper part of the coal conveying belt 6. The identification device 7 is used to automatically identify whether the biomass briquette or coal is transported on the coal conveying belt 6. A belt scale 8 is arranged at the rear end of the coal conveying belt 6, which is used to weigh the biomass briquette or coal transported on the coal conveying belt 6. A sampling machine 9 is arranged at the rear end of the belt scale 8, which is used to automatically sample the coal transported on the coal conveying belt 6. The tail part of the coal conveying belt 6 is divided into two belts, which are an A-side belt 10 and a B-side belt 11. The A-side belt 10 is connected with a biomass bin 12, and the B-side belt 11 is connected with a raw coal bin 13. The biomass briquette on the coal conveying belt 6 enters the biomass bin 12 through the A-side belt 10, and the coal on the coal conveying belt enters the raw coal bin 13 through the B-side belt 11.

[0027] The method for controlling the operation of the coal conveying belt 6, the belt scale 8, the sampling machine 9, the biomass bin 12 and the raw coal bin 13 is shown in Figure 2 According to the signal of the identification device 7, the type of the fuel transported on the coal conveying belt is determined. If it is determined that the biomass briquette is transported on the coal conveying belt, the weighing data of the belt scale 8 is counted into the biomass module, and the sampling machine is stopped. Then the A-side belt 10 is started, the B-side belt 11 is stopped, and the biomass briquette on the coal conveying belt 6 is sent into the biomass bin 12. If it is determined that the coal is transported on the coal conveying belt, the weighing data of the belt scale 8 is counted into the coal module, and the sampling machine 9 is started. Then the B-side belt 11 is started, the A-side belt 10 is stopped, and the coal on the coal conveying belt is sent into the raw coal bin 13.

[0028] The discharge outlets of the biomass bin 12 and the raw coal bin 13 are connected with the inlet of a coal mill 14. When the unit is in low load, the outlet of the raw coal bin 13 is closed, the biomass briquette in the biomass bin 13 enters the coal mill 14, is carried into a coal powder burner 18 by primary air, is burned, and the generated heat enters a boiler 19. When the boiler 19 is in high load, the outlet of the biomass bin 12 is closed, the coal in the raw coal bin 13 enters the coal mill 14, is pulverized, is carried into the coal powder burner 18 by the primary air, is burned, and the generated heat enters the boiler 19. The flue gas generated by the combustion of the boiler 19 passes through an air preheater 21 arranged at the tail flue of the boiler 19 to recover the waste heat of the flue gas. The primary air heated by the air preheater is adjusted by a hot primary air valve, is mixed with cold primary air, and provides a wind-powder mixed medium with a suitable temperature for the coal mill, so as to ensure the drying and stable combustion of the biomass / coal powder.

[0029] An electric dust collector 22 is arranged in the flue of the air preheater 21, which adsorbs the fly ash in the flue gas by a high-voltage electrostatic field to remove the dust particles in the flue gas. The primary air entering the coal mill 14 is supplied by a primary air fan 20. The outlet of the primary air fan 20 is split into two paths: one connected to the air preheater 21, and the other connected to the cold primary air valve 17. The outlet of the air preheater 21 is connected to the hot primary air valve 16. The flow rate of the hot primary air is regulated by the hot primary air valve 16, and then it is mixed with the cold primary air from the cold primary air outlet, and then enters the coal mill 14 through the primary air valve 15.

[0030] The switching between biomass briquettes and coal feed into the furnace is performed according to the unit load command, and the control method is as follows: Figure 3 As shown, this specifically involves the control of biomass compartment 12, raw coal compartment 13, primary air valve 15, hot primary air valve 16, and cold primary air valve 17. When the unit load command is higher than 75% THA, the outlet of biomass compartment 12 is closed, the outlet of raw coal compartment 13 is opened, and the coal in raw coal compartment 13 enters the coal mill 14. The opening of primary air valve 15 decreases, reducing the air-to-coal ratio entering the coal mill 14; the opening of cold primary air valve 17 decreases; and the opening of hot primary air valve 16 increases, raising the primary air inlet temperature entering the coal mill 14. When the unit load command is lower than 75% THA, the outlet of biomass compartment 12 is opened, the outlet of raw coal compartment 13 is closed, and the biomass briquettes in biomass compartment 12 enter the coal mill 14. The opening of primary air valve 15 increases, increasing the air-to-coal ratio entering the coal mill 14; the opening of cold primary air valve 17 increases; and the opening of hot primary air valve 16 decreases, lowering the primary air inlet temperature entering the coal mill 14.

[0031] The primary air valves, hot primary air valves, and cold primary air valves automatically adjust according to load changes, controlling the air-to-coal ratio and air temperature. The air preheater and primary air fan work together to achieve efficient utilization of heat and air volume. The entire system adopts a modular design, facilitating maintenance and expansion.

[0032] The identification device uses a visual recognition sensor, model GT-12, and is equipped with an image recognition algorithm that can accurately identify biomass briquettes and coal.

[0033] like Figure 4 As shown, the specific process is as follows: S1, the visual recognition sensor continuously or periodically captures images of the fuel (biomass briquettes or coal) being transported on the coal conveyor belt 6; S2, Preprocess the image: Use filters (such as median filtering, Gaussian filtering) to remove noise from the image, adjust the image brightness and contrast to make the fuel features (texture, color) more obvious, and perform grayscale processing and image size normalization processing to locate the fuel area on the belt in the image and eliminate belt background and edge interference.

[0034] S3, from the pre-processed image, using a random forest algorithm to extract features and classify the collected images, which can distinguish the key visual attributes of biomass briquettes and coal. The extracted features include the shape, size, surface texture, etc. of the fuel, specifically: Texture features: Calculate contrast, energy, entropy, homogeneity, correlation, etc. to quantify the roughness, regularity, and graininess of the fuel surface. Biomass briquettes usually have more regular, smoother, or specific grain / bar texture than raw coal; raw coal usually has more irregular, rough, and fragmented texture.

[0035] Color features: Color histogram: Statistics of the distribution of different colors (RGB, HSV space) in the image or ROI. Biomass briquettes (such as wood pellet particles) may appear yellow-brown, brown, while coal usually appears black, dark gray. Color mean, variance, etc.

[0036] Shape features: If biomass briquettes are regular particles (such as cylinders, cubes) and coal pieces have highly irregular shapes, contour features (area, perimeter, circularity, rectangularity, Hu matrix, etc.) can be extracted.

[0037] Edge features: Edge density, edge direction histogram, etc., reflecting the clarity and complexity of the object's outline; coal edges may be sharper and more fragmented.

[0038] Feature vector: Combine multiple extracted feature values into a numerical vector, representing the image sample.

[0039] S4, construct a sample image dataset from the extracted features, train a random forest model, and output a random forest model containing multiple decision trees, specifically: Select the most discriminative and least redundant feature subset from a large number of extracted features (clearly know whether each picture is "biomass briquette" or "coal"), construct a sample image dataset; Divide the sample dataset into training and test sets.

[0040] Initialize random forest model parameters: number of decision trees, maximum number of features considered when splitting nodes of each tree, maximum depth of tree, minimum number of samples in leaf nodes, etc.

[0041] Randomly extract multiple sub-sample sets from the training set; Decision tree construction: For each sub-sample set, construct a decision tree; when splitting nodes in the decision tree, randomly select a subset (size controlled by parameters) from all features, then find the optimal feature and split point (such as minimum Gini impurity or maximum information gain) in the subset to split the node.

[0042] No pruning (or light pruning): usually let the tree grow to the maximum depth or until the number of leaf node samples is less than the minimum value; The trained random forest model contains multiple decision trees. S5, fuel type identification: Real-time acquisition and pre-processing of fuel images and feature extraction (possibly plus feature selection) of the corresponding feature vectors; Input the feature vector into the trained random forest model; Each tree makes an independent prediction: the feature vector starts from the root node of each decision tree, and according to the splitting rule (feature threshold judgment) on the node, it is passed down layer by layer, and finally reaches a certain leaf node. The majority class label (biomass or coal) contained in this leaf node is the prediction result of this tree.

[0043] Integrated voting: after all decision trees make predictions, the random forest adopts a majority voting mechanism. Count the number of votes for "biomass briquette" and "coal".

[0044] Final decision: the class with the most votes (e.g. more than 50% of the total number of trees) is the final identification result of the random forest model for the fuel type in the image ("biomass briquette" or "coal").

[0045] Output the final identification result ("biomass briquette" or "coal") as the core signal to the DCS control system. According to this identification signal, execute the pre-set control logic: If it is biomass briquette: start A side belt (10), close B side belt (11), stop sampler (9).

[0046] If it is coal: start B side belt (11), close A side belt (10), start sampler (9).

[0047] According to the classification result, determine the fuel type, which is biomass briquette or coal.

[0048] Use the random forest-based image recognition algorithm to identify the fuel type, and the algorithm flow is as follows Figure 4As shown, it is divided into two parts of training stage and identification stage. In the training stage, first, a large number of learning set images with labeled fuel type labels are collected, the images cover various forms of biomass fuel and coal fuel on the coal conveying belt. Then, the learning set images are uniformly preprocessed, including grayscale, binarization and region extraction, then the threshold segmentation method is used to extract the fuel main region to complete the image segmentation, and four types of feature parameters of area, eccentricity, compactness and average gray value are extracted from the fuel main region, finally, the feature parameters are input into the random forest model together with the corresponding image labels to train the classifier. After entering the identification stage, the identification device collects the fuel images on the coal conveying belt, then the fuel images are preprocessed, and the extracted image features are sent to the trained random forest model for identification and judgment. In order to improve the robustness and anti-interference ability of the identification algorithm, a 10-frame majority voting mechanism is introduced in the identification stage, that is, 10 consecutive images are identified respectively, and the identification results are counted, and the majority result is taken as the final judgment of the fuel type.

[0049] The belt scale adopts an electronic scale, model BL-300, with high-precision weighing function. The sampling machine adopts an automatic sampling device, model GSL-30, which can periodically sample and analyze the fuel.

[0050] The control system adopts a DCS system, realizing intelligent control and data acquisition of the whole system. The measurement accuracy of the belt scale 8 is not less than ±0.5%, and the measurement data can be stored to the biomass module and the coal module respectively. The biomass briquette fuel transport vehicle 1 and the coal transport vehicle 3 adopt a conventional load vehicle. In the power industry, THA is the abbreviation of Turbine Heat Acceptance, which represents the rated load or performance benchmark of the steam turbine under certain conditions. Specifically, the THA condition refers to the condition that the steam turbine can continuously and stably operate and output rated power under the conditions of rated inlet parameters, rated back pressure, normal operation of the regenerative system, and 0% water supply rate. This condition is the ideal operating state with the highest thermal efficiency of the steam turbine, and is often used as a benchmark for performance evaluation.

[0051] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "low temperature", "medium temperature", "high temperature" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0052] It should be noted that the terms "first", "second", and the like, used in the description and the claims of the present application as well as above-mentioned drawings of the application, are used to differentiate similar objects, and are not necessarily used to describe a particular sequential or chronological order. It is to be understood that the terms so used in the description are interchangeable under appropriate circumstances and embodiments of the application described herein are capable of operating in other sequences than those explicitly described or illustrated herein. Further, the terms "comprise", "comprising", "include", "including", and the like, used in the description and the claims of the present application, and above-mentioned drawings of the application, are used in the sense of "including but not limited to".

[0053] In the present application, unless specifically defined otherwise, the terms "mount", "connected", "connecting", "fixed", "fixedly connected", and the like, are used broadly and encompass both direct and indirect mounting, connecting, and / or fixed connections, as well as mechanical and electrical connections and / or communications, whether or not it is stated that one element is, for example, directly connected to another element. It is to be understood that the terms and words described herein are not limited to the direct and literal relationships as understood by an individual of ordinary skill in the art based on the context of the words and terms.

[0054] In the present application, unless specifically defined otherwise, "on", "above", and "under" of a first feature in relation to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above", and "under" of a first feature in relation to a second feature include that the first feature is directly above and obliquely above the second feature, or that the first feature is merely higher in horizontal level than the second feature. "On", "above", and "under" of a first feature in relation to a second feature include that the first feature is directly above and obliquely above the second feature, or that the first feature is merely lower in horizontal level than the second feature.

[0055] It should be understood that the terms "comprise" and "include", when used in this specification and in the following claims, indicate the presence of the described features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0057] The above description is only the preferred embodiment of the present application, not any form of limitation to the present application; anyone skilled in the art can easily implement the present application according to the drawings and the above description; however, anyone skilled in the art can make some changes, modifications and equivalent variations of the above-mentioned technical contents within the scope of the technical solutions of the present application, which are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and variations of the above-mentioned embodiments according to the essential technology of the present application are still within the protection scope of the technical solutions of the present application.

Claims

1. A method for controlling the blending of biomass briquette fuel in a thermal power plant, characterized in that, The method comprises the following steps: An image recognition algorithm based on random forest is adopted to determine the fuel type on the coal conveying belt (6) through the recognition device (7); If it is biomass briquette, the A-side belt (10) is started and the B-side belt (11) is closed, and the sampler (9) is stopped working; If it is coal, the B-side belt (11) is started and the A-side belt (10) is closed, and the sampler (9) is started working; The fuel weight is measured in real time through the belt scale (8), and the data is recorded into the biomass module or the coal module respectively, and the fuel is stored in the biomass storage bin (12) or the raw coal storage bin (13) after being sorted; According to the unit load instruction, the biomass briquette and the coal are switched for entering the furnace, when the load instruction is higher than 75%THA, the biomass storage bin (12) outlet is closed and the raw coal storage bin (13) outlet is opened; when the load instruction is lower than 75%THA, the raw coal storage bin (13) outlet is closed and the biomass storage bin (12) outlet is opened.

2. The method according to claim 1, wherein the biomass briquette is used in a thermal power plant. An image recognition algorithm based on random forest is adopted to determine the fuel type on the coal conveying belt (6) through the recognition device (7), specifically: S1, the recognition device (7) continuously or periodically captures the fuel image being conveyed on the coal conveying belt (6); S2, the fuel image is preprocessed by denoising, gray scaling and normalization; S3, the random forest algorithm is used to extract features and classify the collected image from the preprocessed fuel image; S4, the random forest model is trained by constructing a sample image data set from the extracted features; S5, the trained random forest model is used for fuel type recognition, and the recognition result of the fuel type is output.

3. The method according to claim 1, wherein the biomass briquette fuel is used in a coal-fired power plant. When the load instruction is higher than 75%THA, the following operations are performed synchronously: The primary air valve (15) opening is reduced to reduce the air-coal ratio; the cold primary air valve (17) opening is reduced and the hot primary air valve (16) opening is increased to increase the inlet air temperature of the coal mill (14).

4. The method according to claim 1, wherein the biomass briquette fuel is used in a thermal power plant. When the load instruction is lower than 75%THA, the following operations are performed synchronously: The primary air valve (15) opening is increased to increase the air-coal ratio; the cold primary air valve (17) opening is increased and the hot primary air valve (16) opening is reduced to reduce the inlet air temperature of the coal mill (14).

5. The method according to claim 1, wherein the biomass briquette is used in a coal-fired power plant. According to the unit load instruction, the biomass briquette and the coal are switched for entering the furnace, specifically: when the unit is in low load, the outlet of the raw coal storage bin (13) is closed, the biomass briquette in the biomass storage bin (12) enters the coal mill (14) for grinding, and then is carried into the coal powder burner (18) for combustion by the primary air, and the generated heat enters the boiler (19); when the boiler is in high load, the outlet of the biomass storage bin (12) is closed, the coal in the raw coal storage bin (13) enters the coal mill (14) for grinding, and then is carried into the coal powder burner (18) for combustion by the primary air, and the generated heat enters the boiler (19).

6. A system for blending biomass briquette in a thermal power plant, characterized in that, It comprises, a fuel conveying and storage unit, a fuel recognition and sorting unit, and a combustion control unit; The fuel identification and metering unit comprises a coal conveying belt (6), a belt scale (8), a sampling machine (9), an A-side belt (10), a B-side belt (11), a biomass bin (12) and a raw coal bin (13), The identification device (7) is arranged on the coal conveying belt (6) and used for identifying the type of fuel transported on the coal conveying belt (6); the belt scale (8) is arranged at the rear end of the coal conveying belt (6) and used for weighing the weight of the fuel transported on the coal conveying belt (6); and the sampling machine (9) is used for automatically sampling coal. The A-side belt (10) and the B-side belt (11) are respectively arranged at the rear end of the coal conveying belt (6), the A-side belt (10) is connected with the biomass bin (12), the B-side belt (11) is connected with the raw coal bin (13), the front end of the coal conveying belt (6) is connected with the fuel conveying and storing unit, and the biomass bin (12) and the raw coal bin (13) are connected with the combustion control unit.

7. The system for blending biomass briquette fuel in a thermal power plant according to claim 6, wherein, The fuel conveying and storing unit comprises a biomass briquette conveying vehicle (1), a coal conveying vehicle (3) and a coal shed (5), and the coal shed (5) is connected with the front end of the coal conveying belt (6).

8. The system for blending biomass briquette fuel in a thermal power plant according to claim 6, characterized in that, The coal shed (5) is divided into multiple independent storage areas and is respectively used for temporarily storing biomass briquettes sampled by the biomass sampling device (2) and coal sampled by the coal sampling device (4).

9. The system for blending biomass briquette fuel in a thermal power plant according to claim 6, wherein, The combustion control unit comprises a coal mill (14), a primary air valve (15), a hot primary air valve (16), a cold primary air valve (17), a pulverized coal burner (18), a boiler (19), a primary air blower (20) and an air preheater (21). The discharge outlets of the biomass bin (12) and the raw coal bin (13) are connected with the inlet of the coal mill (14), the outlet of the coal mill (14) is connected to the boiler (19) through the pulverized coal burner (18), the outlet of the primary air blower (20) is divided into two paths, one path is connected to the hot primary air valve (16) through the air preheater (21), and the other path is connected to the cold primary air valve (17), and the outlets of the hot primary air valve (16) and the cold primary air valve (17) are connected to the coal mill (14) through the primary air valve (15) after being merged. The identification device (7) is a visual identification sensor and is used for distinguishing biomass briquettes from coal.

10. The system for blending biomass briquette fuel in a thermal power plant according to claim 6, wherein, ​

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