Method for measuring blending combustion amount of biomass fuel in co-grinding mode and blending combustion system

Abstract

The invention provides a method for measuring the blending combustion amount of biomass fuel in a co-grinding mode and a blending combustion system, and the method comprises the following specific steps: obtaining an internal image when a coal feeder is empty, and extracting an empty bin pixel gray value of the internal image when the coal feeder is empty; obtaining an internal image of the coal feeder when the fuel enters the coal feeder, and extracting a feeding pixel gray value of the internal image when the fuel enters the coal feeder; and comparing the empty bin pixel gray value with the feeding pixel gray value to confirm the fuel type, obtaining the weight of the fuel, and transmitting the weight of the fuel to a fuel quality database of the corresponding type to obtain biomass fuel blending combustion amount data. Accurate measurement of the blending combustion amount of the biomass fuel is achieved through an image processing algorithm. The method is easy to operate, high in precision and suitable for an existing carbon emission checking method. The system can operate continuously and stably only by installing a detection device at an outlet of the coal feeder, and is not influenced by biomass types and blending combustion proportions.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass blending and burning, and in particular to a method for measuring the blending and burning amount of biomass fuel in a co-grinding mode and a blending and burning system. Background Art

[0002] Using large-scale, high-efficiency coal-fired units to co-fire biomass fuels for power generation is an advanced technology for achieving efficient utilization of biomass. It can not only significantly improve the efficiency of biomass power generation and save biomass resources, but also significantly reduce the carbon emissions of coal-fired power units and improve the flexibility of coal-biomass coupled power generation, thereby enhancing the sustainability of coal-fired power generation. It is a realistic and feasible path for coal-fired power generation to move towards low-carbonization.

[0003] Biomass is a zero-carbon fuel, requiring precise measurement of its blending ratio to determine the level of carbon emissions reduction achieved by coal-fired units. Biomass fuel ratio measurement can be categorized into two technologies: front-end monitoring and back-end monitoring, depending on the data collection and detection locations. The front-end monitors the characteristics and mass flow of the coal and biomass fed into the boiler in real time to determine the biomass content. Back-end monitoring determines the biomass fuel ratio based on the composition of the flue gas emitted by the power plant.

[0004] The principle of biomass front-end monitoring technology primarily relies on distinguishing the different optical properties of biomass and coal to determine the biomass blend ratio. For example, infrared spectroscopy uses differences in the Bragg diffraction effect of light waves on different objects to distinguish biomass proportions. X-ray spectroscopy uses the difference in the amount of X-rays remaining after projecting X-rays through coal and biomass to determine the mass ratio and type of biomass and coal. Additionally, some researchers have proposed methods for identifying biomass blend ratios based on a combination of online photography and intelligent recognition algorithms. Wu Yuxin et al. proposed a method for determining the biomass and coal blend ratio based on a combination of online photography and weighing. By taking laboratory photos of biomass and coal blends at varying ratios, they trained a convolutional neural network model based on a database of these images. The convolutional neural network algorithm then performed online biomass blend ratio identification, achieving a measurement error of less than 10%. The advantages of these methods lie in their simplicity and low maintenance costs. However, research is still limited, resulting in online measurement accuracy that falls short of meeting industrial requirements. Further improvement is needed through the integration of weighing and density recognition methods. In actual applications, there are some mechanical structures that can achieve measurement, such as a biomass crushing fuel combined bulk density metering box developed by Hu Zhenxi and others, which can convert weight through actual volume and use the difference in density to analyze the ratio of coal and biomass. However, there are still some defects in actual applications.

[0005] The biomass back-end measurement method mainly utilizes the difference in flue gas composition produced after the combustion of biomass and coal, and infers the biomass blending ratio by measuring the changes in flue gas composition. For example, the SO2-based flue gas composition determination method utilizes the difference in sulfur content between biomass and coal, and infers the biomass content by measuring the changes in SO2 content in the flue gas. A. Spears et al. conducted a co-combustion test on high-sulfur coal from the UK with typical biomass such as rice husks and bamboo, verifying the feasibility of this method. However, the study also showed that because the amount of SO2 generated varies nonlinearly with the mixing ratio, the accuracy of this method in measuring the biomass blending ratio is difficult to meet the requirements.

[0006] Currently, it is difficult to obtain a recognized biomass fuel blending ratio or biomass power generation capacity in direct biomass combustion, especially when using co-grinding and co-combustion. Both coal and biomass enter the furnace through the pulverizer. It is necessary to first determine the type of fuel entering the pulverizer and then weigh the biomass fuel and coal powder using the same measuring instrument. This is significantly different from the traditional measurement method of identification and weighing on the coal conveyor belt. After research and analysis, it is found that there is currently no mature technology for measuring biomass blending ratios. Existing methods are either insufficiently accurate, too costly, or impractical, making them difficult to implement in practice. Summary of the Invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a method and a blending system for measuring the amount of biomass fuel blended in a co-grinding manner, which realizes the accurate measurement of the amount of biomass fuel blended through an image processing algorithm. The method is simple to operate and has high precision, and is compatible with the current carbon emission verification method. The system only needs to install a detection device at the outlet of the coal feeder to operate continuously and stably, and is not affected by the type of biomass and the blending ratio. In addition, the fuel identification accuracy is improved through multiple judgment conditions, and a correction method for biomass fuel weighing is proposed, which further improves the accuracy of measurement and provides a reliable basis for the carbon quota management of power plants.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for measuring the amount of biomass fuel blended in a co-grinding manner, the specific steps of which are as follows:

[0009] Obtain an internal image of the coal feeder when the bunker is empty, and extract the grayscale value of the empty bunker pixel in the internal image when the bunker is empty;

[0010] Obtain an internal image of the coal feeder when fuel is entering, and extract the grayscale value of the feed pixel of the internal image when fuel is entering;

[0011] The fuel type is confirmed by comparing the grayscale value of the empty pixel and the grayscale value of the fed pixel, and the weight of the fuel is obtained and transmitted to the fuel mass database of the corresponding type to obtain the biomass fuel blending amount data.

[0012] Furthermore, an internal image of the coal feeder is obtained from the coal feeder outlet toward the inside of the coal feeder, and the internal image of the coal feeder is divided into a first recognition area and a second recognition area. The first recognition area is located on the upper part of the coal feeder belt, and the pixel range is m1×n1; the second recognition area is located at the coal feeder belt outlet, and the pixel range is m2×n2.

[0013] Furthermore, in the step of obtaining an internal image of the coal feeder when the bunker is empty and extracting the grayscale value of the empty bunker pixel of the internal image when the bunker is empty:

[0014] The grayscale value of the empty bin pixel includes the grayscale value of the pixel in the first empty bin identification area and the grayscale value of the pixel in the second empty bin identification area, where:

[0015] Normalize the grayscale values of each pixel in the first recognition area and then take the average value to obtain the grayscale value of the pixel in the empty warehouse first recognition area;

[0016] The grayscale values of the pixels in the second recognition area are normalized and then averaged to obtain the grayscale values of the pixels in the empty warehouse second recognition area.

[0017] Furthermore, in the step of obtaining an internal image of the coal feeder when fuel is fed into the coal feeder and extracting the grayscale value of the feed pixel of the internal image when fuel is fed into the coal feeder:

[0018] The grayscale value of the feed pixel includes the grayscale value of the pixel in the first identification area of the feed and the grayscale value of the pixel in the second identification area of the feed, wherein:

[0019] Normalizing the grayscale values of the pixels in the first identification area and taking the average value to obtain the grayscale value of the pixels in the first identification area of the feed;

[0020] The grayscale values of the pixels in the second identification area are normalized and then averaged to obtain the grayscale values of the pixels in the second identification area of the feed.

[0021] Furthermore, in the step of comparing the grayscale value of the empty pixel with the grayscale value of the charged pixel to determine the fuel type:

[0022] When the grayscale value of the pixel in the empty first identification area is greater than the grayscale value of the pixel in the fed first identification area, and the number of the pixel grayscale value in the empty second identification area equal to the pixel grayscale value in the fed second identification area is zero, the fuel type is pulverized coal;

[0023] When the grayscale value of the pixel in the empty warehouse first identification area is less than the grayscale value of the pixel in the feeding first identification area, and the number of the pixel grayscale value in the empty warehouse second identification area is equal to the pixel grayscale value in the feeding second identification area satisfies: When , the fuel type is biomass fuel;

[0024] Among them, α is the correction coefficient of the coal feeder belt speed.

[0025] Furthermore, the grayscale value of the empty pixel and the grayscale value of the fed pixel are compared to confirm the fuel type, obtain the weight of the fuel, and transmit it to the fuel mass database of the corresponding type to obtain the biomass fuel blending amount data:

[0026] The weight of the biomass fuel weighed by the coal feeder belt is corrected using the correction coefficient to obtain the accurate weight of the biomass fuel and transmit it to the biomass fuel quality database;

[0027] The correction coefficient is the ratio of the actual biomass fuel weight to the biomass fuel weight measured by the coal feeder belt.

[0028] The present invention also provides a biomass fuel blending system in a co-grinding mode, comprising: a detection device, the detection device being arranged on an observation hole at a coal feeder outlet, the detection device being connected to a server, the server having a built-in method for measuring the amount of biomass fuel blending in a co-grinding mode, for distinguishing fuel types based on internal images of the coal feeder when empty and when fuel is entering, obtained by the detection device, and transmitting the images to a DCS control system;

[0029] A belt scale is installed inside the coal feeder. The DCS control system obtains the current fuel weight measured by the belt scale, calibrates the fuel weight using the above method, and then transmits it to the fuel quality database of the corresponding type.

[0030] Furthermore, the detection device includes an explosion-proof infrared camera and a binocular fill light device.

[0031] Furthermore, the wavelength band of the explosion-proof infrared camera is 10 μm to 14 μm; the binocular fill light device adopts a sodium lamp light source.

[0032] Furthermore, the fuel types include coal and biomass fuel, which are fed into the coal feeder (3) in different time periods. The coal and biomass fuel are fed into the pulverizer through the coal feeder for pulverization, and then carried into the pulverized coal burner by the primary air to burn in the boiler to release heat.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] The present invention provides a method for measuring the amount of biomass fuel blended in a co-grinding manner. By utilizing an image processing algorithm and comparing the grayscale values of internal images of a coal feeder when empty and when fed, high-precision identification of the fuel type is achieved. This fuel identification method based on image processing fully utilizes the differences in image color and edge shape between biomass fuel and coal, establishes multiple judgment conditions, and thus significantly improves the accuracy of fuel identification. The method of the present invention can process biomass fuels of different types and blending ratios, and is not limited by the specific type or blending ratio of the biomass fuel. It only needs to collect internal images of the coal feeder when empty and when fed, and is easy to operate.

[0035] Furthermore, the present invention divides the internal image of the coal feeder into a first identification area and a second identification area, and calculates the grayscale values of the empty bin pixels and the fed pixels in these two areas. By comparing these grayscale values, it can accurately distinguish between pulverized coal and biomass fuel.

[0036] Furthermore, to address the problem of large errors when weighing biomass fuel on a belt scale due to its lower bulk density than pulverized coal, the present invention uses the ratio of the actual biomass fuel weight measured on a floor scale to the biomass fuel weight measured on a coal feeder belt scale as a correction factor to calibrate the biomass fuel weight measured on the coal feeder belt scale. This correction method can significantly improve the accuracy of biomass fuel measurement, providing more reliable and authentic measurement data for power plants applying for carbon quota management.

[0037] The blending system of the present invention requires only a single detection device installed at the coal feeder outlet to accurately measure the amount of biomass fuel blended. This simple system architecture not only reduces installation cost and difficulty, but also improves system reliability and stability. Furthermore, since the system primarily relies on image processing algorithms and belt scale weighing data, maintenance is relatively simple and convenient. Regular calibration and inspection of the detection device and belt scale are sufficient to ensure proper operation and measurement accuracy.

[0038] The blending system of the present invention can accurately identify different types of fuels and accurately correct the weighing data. It has strong adaptability and can handle biomass fuels of different types and blending ratios to meet the diverse fuel needs of power plants. Currently, the main basis for calculating carbon emissions in coal-fired power plants is the amount of coal entering the furnace weighed at the coal feeder. The system of the present invention obtains more accurate boiler carbon emission data by identifying coal powder and biomass fuel inside the coal feeder and sending their weighing data to the corresponding database for measurement. This helps power plants accurately calculate carbon emissions and can also provide a strong basis for the power plant to apply for carbon quota management. At the same time, because the system's measurement method is most consistent with the current carbon emission verification method, the measurement data it provides is also more easily recognized and accepted by relevant departments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the composition of a biomass fuel blending system in a co-grinding mode of the present invention;

[0040] In the attached figure: 1. Coal yard; 2. Raw coal bin; 3. Coal feeder; 4. Coal mill; 5. Pulverized coal burner; 6. Boiler; 7. Detection device; 8. Server; 9. DCS control system.

[0041] Figure 2 Flowchart of the image processing algorithm of the present invention;

[0042] Figure 3 The image signal collected by the detection device of the present invention when the coal feeder has an empty bin;

[0043] Figure 4 The image signal collected by the detection device of the present invention when the coal feeder is loading coal;

[0044] Figure 5 The detection device of the present invention collects image signals when biomass is loaded onto a coal feeder. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] like Figure 1 As shown, the present invention provides a biomass fuel blending system in a co-grinding mode, including a coal yard 1, a raw coal bin 2, a coal feeder 3, a coal mill 4, a pulverized coal burner 5, a boiler 6, a detection device 7, a server 8 and a DCS control system 9. Specifically:

[0047] Among them: coal and biomass fuel are stored in different areas in coal yard 1 and cannot be mixed.

[0048] Coal and biomass fuel are fed into the raw coal bunker 2 in different time periods. When there is biomass fuel in the raw coal bunker 2, pulverized coal fuel cannot be fed in. Pulverized coal fuel can only be fed in after the raw coal bunker 2 is emptied.

[0049] Coal and biomass fuel are fed into the coal feeder 3 in different time periods. Coal and biomass fuel are fed into the coal mill 4 through the coal feeder 3 for pulverization, and then carried into the pulverized coal burner 5 by the primary air, and burned in the boiler 6 to release heat.

[0050] A detection device 7 is installed at the outlet of the coal feeder 3 to obtain the internal image signal of the coal feeder 3, and then identify the type of fuel in the coal feeder 3 through an image processing algorithm, and send the fuel type signal and coal feeder weighing data to the DCS control system 9.

[0051] Furthermore, the detection device 7 is installed on the observation hole at the outlet of the coal feeder 3 and includes an explosion-proof infrared camera and a binocular fill light device. The infrared camera selects the 10μm to 14μm band, and the binocular fill light device uses a sodium lamp as a light source. A belt scale is installed inside the coal feeder 3.

[0052] Furthermore, after the explosion-proof infrared camera acquires the image signal, it is sent to the server 8. In the server 8, the image signal is processed using an image processing algorithm to obtain a fuel type signal which is then sent to the DCS control system 9.

[0053] Furthermore, in the DCS control system 9, the weighing data of the coal feeder 3 is stored in the metering database of the corresponding fuel according to the fuel type signal, as a data certificate for calibrating the carbon emissions of the boiler.

[0054] The process of the image processing algorithm of the present invention is as follows Figure 2 As shown in the figure, an explosion-proof infrared camera is installed on the coal feeder 3 to capture video images from inside the feeder 3. This video image is then used for image recognition to determine the type of fuel entering the feeder 3. If biomass fuel is identified, the feeder 3's belt scale is used for weighing and measurement. The weight data is then corrected and sent to the DCS's biomass quality database. If coal is identified, the feeder's belt scale is used for weighing and measurement, and the weight data is sent to the DCS's coal quality database.

[0055] Furthermore, the image recognition method of the present invention is as follows Figures 3 to 5 First, when the coal feeder is empty, an explosion-proof infrared camera is used to obtain the internal image of the coal feeder, as shown in the figure. Figure 3 As shown in the figure, the image is divided into the first recognition area and the second recognition area. The first recognition area is located on the upper part of the coal feeder belt, with a pixel range of m1×n1; the second recognition area is located at the outlet of the coal feeder belt, with a pixel range of m2×n2. The grayscale value of each pixel in the first recognition area is extracted, normalized, and averaged to obtain the grayscale value G of the pixel in the first recognition area of the empty bin. k , as shown below:

[0056]

[0057] Where G i,j is the grayscale value of each pixel in the first recognition area, and i and j are the horizontal and vertical coordinates of the pixel respectively.

[0058] Extract the grayscale value of each pixel in the second recognition area to obtain the grayscale value B of the second recognition area of the empty warehouse k (i,j).

[0059] When the fuel starts to enter the coal feeder 3, the detection device 7 is used to obtain the internal image of the coal feeder 3, and then the gray value of each pixel in the first identification area is extracted, and the average value is obtained after normalization to obtain the gray value G of the pixel in the first identification area of the feed. y ; Extract the grayscale value of each pixel in the second identification area to obtain the grayscale value of the pixel in the second identification area of the feed B y (i, j), and then compared with the image of the coal feeder when it is empty, and statistically analyzed B y (i,j) and B kWhen both formula (2) and formula (3) are satisfied, it is determined that the fuel entering the coal feeder is pulverized coal, such as Figure 4 When one of the equations (2) or (3) is not satisfied, the calculation proceeds to the next image.

[0060] G y <G k (2)

[0061] C ount=0(3)

[0062] When both formula (4) and formula (5) are satisfied, it is determined that the fuel entering the coal feeder is biomass, such as Figure 5 When one of the equations (4) or (5) is not satisfied, the calculation proceeds to the next image.

[0063] G y >G k (4)

[0064]

[0065] Among them, α is the correction coefficient of the coal feeder belt speed.

[0066] Furthermore, the correction coefficient of the biomass fuel weighing data of the present invention is η, and the interval time t is set. The biomass fuel passes through the coal feeder belt and the coal feeder belt weighing data m is recorded. p Then take the biomass fuel out of the coal feeder and weigh the actual weight m on the scale. r , and then the correction coefficient η when the belt scale weighs biomass fuel is obtained, as shown in Formula 6.

[0067]

[0068] Based on the correction coefficient and the weighing data of the coal feeder belt scale, the actual amount of biomass fuel entering the furnace can be converted.

[0069] The blending system of the present invention only needs to install a detection device at the outlet of the coal feeder, and then use the image processing algorithm and the belt scale weighing data to measure the mass of biomass entering the furnace. The system is not affected by the type of biomass and the blending ratio, is simple to operate, and can operate continuously and stably. The image processing algorithm uses the differences in image color and edge shape between biomass fuel and coal to establish multiple judgment conditions, thereby improving the accuracy of identifying the two fuels of biomass and coal. The bulk density of biomass fuel is less than that of coal powder, and a large error will be generated when weighed on the belt scale. Correcting the weight of biomass fuel by the correction coefficient can significantly improve the accuracy of biomass fuel measurement. At present, the main basis for calculating carbon emissions in coal-fired power plants is the amount of coal entering the furnace weighed at the coal feeder. The blending system provided by the present invention obtains accurate boiler carbon emission data by identifying coal powder and biomass fuel inside the coal feeder, and then sending the weighing data of coal powder and biomass fuel into the corresponding database for measurement. Since the weighing of coal and biomass is completed on the coal feeder belt, it is most consistent with the current carbon emission verification method. Therefore, the method of measuring the biomass fuel blending amount proposed in the present invention can obtain more real and reliable biomass fuel blending amount measurement data, providing a certificate basis for power plants to declare carbon quota management.

Claims

1. A method for measuring the amount of biomass fuel blended in a co-grinding mode, characterized in that: The specific steps are as follows: Obtain an internal image of the coal feeder when the bunker is empty, and extract the grayscale value of the empty bunker pixel in the internal image when the bunker is empty; Obtain an internal image of the coal feeder when fuel is entering, and extract the grayscale value of the feed pixel of the internal image when fuel is entering; The fuel type is confirmed by comparing the grayscale value of the empty pixel and the grayscale value of the fed pixel, and the weight of the fuel is obtained and transmitted to the fuel mass database of the corresponding type to obtain the biomass fuel blending amount data.

2. The method for measuring the amount of biomass fuel blended in a co-grinding mode according to claim 1, characterized in that: The internal image of the coal feeder is obtained from the coal feeder outlet toward the inside of the coal feeder. The internal image of the coal feeder is divided into a first recognition area and a second recognition area. The first recognition area is located on the upper part of the coal feeder belt, and the pixel range is m1×n1; the second recognition area is located at the coal feeder belt outlet, and the pixel range is m2×n2.

3. The method for measuring the amount of biomass fuel blended in a co-grinding mode according to claim 2, characterized in that: In the steps of obtaining an internal image of a coal feeder when the bin is empty and extracting the grayscale value of the empty bin pixel of the internal image when the bin is empty: The grayscale value of the empty bin pixel includes the grayscale value of the pixel in the first empty bin identification area and the grayscale value of the pixel in the second empty bin identification area, where: Normalize the grayscale values of each pixel in the first recognition area and then take the average value to obtain the grayscale value of the pixel in the empty warehouse first recognition area; The grayscale values of the pixels in the second recognition area are normalized and then averaged to obtain the grayscale values of the pixels in the empty warehouse second recognition area.

4. The method for measuring the amount of biomass fuel blended in a co-grinding manner according to claim 3, characterized in that: In the steps of obtaining an internal image of the coal feeder when fuel is fed in and extracting the grayscale value of the feed pixel of the internal image when fuel is fed in: The grayscale value of the feed pixel includes the grayscale value of the pixel in the first identification area of the feed and the grayscale value of the pixel in the second identification area of the feed, wherein: Normalizing the grayscale values of the pixels in the first identification area and taking the average value to obtain the grayscale value of the pixels in the first identification area of the feed; The grayscale values of the pixels in the second identification area are normalized and then averaged to obtain the grayscale values of the pixels in the second identification area of the feed.

5. The method for measuring the amount of biomass fuel blended in a co-grinding manner according to claim 4, characterized in that: In the step of comparing the grayscale values of empty pixels and the grayscale values of charged pixels to determine the fuel type: When the grayscale value of the pixel in the empty first identification area is greater than the grayscale value of the pixel in the fed first identification area, and the number of the pixel grayscale value in the empty second identification area equal to the pixel grayscale value in the fed second identification area is zero, the fuel type is pulverized coal; When the grayscale value of the pixel in the empty warehouse first identification area is less than the grayscale value of the pixel in the feeding first identification area, and the number of the pixel grayscale value in the empty warehouse second identification area is equal to the pixel grayscale value in the feeding second identification area satisfies: When , the fuel type is biomass fuel; Among them, α is the correction coefficient of the coal feeder belt speed.

6. The method for measuring the amount of biomass fuel blended in a co-grinding manner according to claim 1, characterized in that: Compare the grayscale value of the empty pixel with the grayscale value of the fed pixel to confirm the fuel type, obtain the weight of the fuel, and transmit it to the fuel mass database of the corresponding type to obtain the biomass fuel blending amount data: The weight of the biomass fuel weighed by the coal feeder belt is corrected using the correction coefficient to obtain the accurate weight of the biomass fuel and transmit it to the biomass fuel quality database; The correction coefficient is the ratio of the actual biomass fuel weight to the biomass fuel weight measured by the coal feeder belt.

7. A biomass fuel blending system in a co-grinding mode, characterized in that: include: A detection device (7), the detection device (7) is arranged on the observation hole of the coal feeder (3) outlet, the detection device (7) is connected to the server (8), and the server (8) is built with the method for measuring the amount of biomass fuel blending in a co-grinding mode according to any one of claims 1 to 5, and is used to distinguish the type of fuel based on the internal images of the coal feeder when the coal feeder is empty and when the fuel is entering, obtained by the detection device (7), and transmit the images to the DCS control system (9); A belt scale is installed inside the coal feeder (3), and the DCS control system (9) obtains the current weight of the fuel weighed by the belt scale, calibrates the weight of the fuel using the method described in claim 6, and then transmits it to the fuel quality database of the corresponding type.

8. The biomass fuel blending system in a co-grinding mode according to claim 7 is characterized in that: The detection device (7) comprises an explosion-proof infrared camera and a binocular light-filling device.

9. The biomass fuel blending system in a co-grinding mode according to claim 8, characterized in that: The waveband of the explosion-proof infrared camera is 10 μm to 14 μm; the binocular fill light device adopts a sodium lamp light source.

10. The biomass fuel blending system in a co-grinding mode according to claim 7, characterized in that: Fuel types include coal and biomass fuel. The coal and biomass fuel are fed into a coal feeder (3) in different time periods. The coal and biomass fuel are fed into a coal mill (4) through the coal feeder (3) for pulverization. The coal and biomass fuel are then carried by primary air into a pulverized coal burner (5) and burned in a boiler (6) to release heat.

Images