A circulating fluidized bed solids circulation rate regulating system based on average particle size

Abstract

This invention discloses a circulating fluidized bed solid circulation rate adjustment system based on average particle size, comprising a solid circulation rate measuring device, a solid particle size measuring device, a storage device, and an adjustment device. Specifically, the solid circulation rate measuring device measures the specific value of the solid circulation rate during circulating fluidized bed operation; the solid particle size measuring device measures the resistance of the compacted solid particles inside the metal tube, compares it with the resistance characteristic curve of the solid particles, and analyzes to obtain the average particle size; the measured solid circulation rate is compared, and if it is within the required operating range, no adjustment is made; if the solid circulation rate is outside the required operating range, the adjustment device controls the discharge rate of the quartz sand bin to change the particle size of the solid particles in the circulating fluidized bed, thereby adjusting the solid circulation rate and realizing the control of the load change of the circulating fluidized bed boiler. This system efficiently and directly solves the problem of solid circulation rate adjustment in circulating fluidized beds, with fast response and excellent effect.

Description

Technical Field

[0001] This invention belongs to the field of circulating fluidized bed boiler combustion technology, specifically relating to a circulating fluidized bed solid circulation rate adjustment system based on average particle size. Background Technology

[0002] Circulating fluidized bed boilers are clean coal combustion equipment, characterized by wide fuel adaptability, combustion temperature lower than pulverized coal furnaces, long fuel residence time in the furnace, and high heat and mass transfer coefficients. They can achieve in-furnace desulfurization and low NOx emissions. x Emissions. With technological advancements, circulating fluidized bed boilers are moving towards larger scale and higher parameters.

[0003] Solid circulation flow rate is a crucial parameter affecting the bed stock, mass balance, and energy balance of circulating fluidized bed (CFB) materials, and is also a key parameter in the design and operation of CFB boilers. A large amount of bed material sits above the air distributor in the furnace of a CFB boiler, playing a role in maintaining furnace temperature. When the CFB load decreases, the primary air volume decreases, corresponding to a decrease in the particle size of the solid particles participating in circulation. More coarse particles concentrate at the bottom of the furnace, while fine particles move upwards, relatively increasing the bed pressure in the dense phase zone. Conversely, when the CFB load increases, the primary air volume increases, carrying more particles to the dilute phase zone and participating in material circulation, relatively decreasing the bed pressure in the dense phase zone. Therefore, during CFB load changes, the solid circulation flow rate can be altered by adjusting the particle size distribution of the circulating material, thereby controlling the load.

[0004] In existing technologies, the solid circulation rate of a circulating fluidized bed is adjusted by increasing or decreasing the primary air volume and controlling slag discharge. This indirect adjustment method is slow to respond and ineffective. Therefore, a system capable of directly adjusting the solid circulation rate of a circulating fluidized bed is needed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a circulating fluidized bed solid circulation rate adjustment system based on average particle size. This system can adjust the solid circulation rate by changing the average particle size of solid particles in the circulating fluidized bed, thereby controlling the load changes of the circulating fluidized bed boiler. It has a fast response and good effect.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A circulating fluidized bed solid circulation flow rate regulation system based on average particle size includes a furnace body, a cyclone separator, a solid circulation flow rate measuring device, a solid particle size measuring device, a storage device, and a regulating device. The flue gas inlet of the cyclone separator is connected to the flue gas outlet of the furnace body, and the discharge port of the cyclone separator is connected to the return inlet of the furnace body in sequence through a riser, a return foot pipe, and a return valve. The solid circulation flow rate measuring device is arranged between the lower end of the riser and the inlet end of the return valve, and is used to measure the solid circulation flow rate during the operation of the circulating fluidized bed. The solid particle size measuring device is arranged between the lower end of the riser and the inlet end of the return valve. Between the inlet end of the return valve, the resistance of the solid particles after compaction in the measuring tube is measured and compared with the resistance characteristic curve of the solid particles to analyze and obtain the average particle size of the solid particles; the storage device consists of multiple quartz sand bins, which are used to store quartz sand with different particle size distribution ranges; the regulating device is connected between the storage device and the riser, and is used to control the discharge rate of each quartz sand bin when the measured value of the solid circulation flow rate is not within the operating requirement range and the average particle size of the solid particles is greater than or less than the set value, thereby increasing the fine or coarse particles, changing the average particle size of the solid particles in the circulating fluidized bed, and thus regulating the solid circulation flow rate.

[0008] As a preferred embodiment of the present invention, the solid circulation flow rate measuring device includes a measuring tube, a first gate, a second gate, a first material control gate, and a level gauge;

[0009] The upper ends of the measuring tube and the return material foot tube are respectively connected to the lower end of the riser to form a three-way pipe structure. The return material foot tube has a first vertical pipe section, the lower end of which is connected to the inlet end of the return material valve. The measuring tube has a second vertical pipe section, the lower end of which is connected to the inlet end of the return material valve through a horizontal pipe. The first gate valve is located at the upper end of the return material foot tube and is used to block the path of solid material flowing from the riser to the return material foot tube. The second gate valve is located at the upper end of the measuring tube and is used to block the path of solid material flowing from the riser to the measuring tube. The first material control valve is located at the connection between the measuring tube and the horizontal pipe and is used to block the path of solid material flowing from the measuring tube to the return material valve. The level gauge is located at the upper end of the second vertical pipe section.

[0010] When measuring the solid circulation flow rate, close the first gate and the first material control gate, open the second gate and start timing; after 10 seconds, open the first gate and close the second gate at the same time to ensure that the solid material passes through the return leg normally and falls into the return valve; record the material level height displayed by the level gauge, and calculate the measured value of the solid circulation flow rate under the current operating conditions according to the solid circulation flow rate calculation formula.

[0011] As a preferred embodiment of the present invention, the formula for calculating the solid circulation flow rate is:

[0012] G s =ρ s *π*D 2 *h / 40;

[0013] Among them, G s Let ρ be the solid circulation flow rate. s The value represents the bulk density of the solid material under operating conditions, where D is the diameter of the measuring tube and h is the material level height measured by the level gauge. (The bulk density characteristic value was determined in the laboratory.)

[0014] As a preferred embodiment of the present invention, the solid particle size measuring device includes a measuring tube, a first gate, a second gate, a first material control gate, a second material control gate, a first differential pressure gauge, a second differential pressure gauge, a first material compaction device, and a second material compaction device.

[0015] The upper end of the measuring tube and the upper end of the return foot tube are respectively connected to the lower end of the vertical pipe to form a three-way pipe structure. The return foot tube is provided with a first vertical pipe section, the lower end of the first vertical pipe section is connected to the inlet end of the return valve, and the measuring tube is provided with a second vertical pipe section, the lower end of the second vertical pipe section is connected to the inlet end of the return valve through a horizontal pipe.

[0016] The first gate valve is located at the upper end of the return foot pipe, used to block the path of solid material flowing from the riser to the return foot pipe; the second gate valve is located at the upper end of the measuring pipe, used to block the path of solid material flowing from the riser to the measuring pipe; the first material control valve is located at the connection between the measuring pipe and the horizontal pipe, used to block the path of solid material flowing from the measuring pipe to the return valve; the second material control valve is located on the horizontal pipe, used to block the path of solid material flowing from the measuring pipe to the return valve; the first material compaction device and The second material compaction device is spaced apart on the second vertical pipe section. Both the first and second material compaction devices are equipped with material gates for opening and closing the measuring pipe. The first differential pressure gauge is installed on the measuring pipe and located above the first material compaction device. The second differential pressure gauge is installed on the horizontal pipe and located between the first material control gate and the second material control gate. The measuring pipe has a first inlet for particle size measuring air input on the side near the second gate. The lower end of the measuring pipe has a second inlet for solid backflushing air input.

[0017] When measuring solid particle size, close the first gate valve, the first material control valve, and the second material control valve, and open the second gate valve to allow solid material to flow into the measuring tube. Open the material gate of the first material compaction device and close the valve of the second material compaction device. After the weight of the material entering the measuring tube meets the set value, open the first gate valve and simultaneously close the second gate valve to ensure that the solid material passes normally through the return leg and falls into the return valve. Close the material gate of the first material compaction device and operate the first and second material compaction devices to compact the material. Connect the particle size measuring air and record the pressure shown by the first and second differential pressure gauges to obtain the resistance of the solid particles after compaction. Compare the pre-established fitting curve of material resistance and average particle size of solid particles to analyze and obtain the average particle size of the solid material. Close the particle size measuring air and open the material gates of the first and second material compaction devices, the first material control valve, and the second material control valve. Connect the solid back-blowing air to transport the solid material in the measuring tube to the return valve. Close the second material control valve, and the solid particle size measurement ends.

[0018] As a preferred embodiment of the present invention, the fitting curve of material resistance and average particle size of solid particles is pre-established through the following steps:

[0019] Step 1: Take a certain mass of solid material from the boiler during operation, sieve it, and group the solid material into groups with a group spacing of 50μm. The mass of each group of solid material is equal to the material mass setting value of the solid particle size measuring device.

[0020] Step 2: Measure the average particle size of different groups of solid materials of the same mass;

[0021] Step 3: Load different groups of solid materials into the measuring tube and measure the resistance of particles of each size;

[0022] Step 4: Plot the resistance of each particle size measured in Step 3 against the average particle size of the solid material measured in Step 2 on graph paper, and fit the graph to obtain the fitting curve of the material resistance versus the average particle size of the solid particles.

[0023] As a preferred embodiment of the present invention, the second material compaction device is provided with a weighing sensor for measuring the weight of the solid material falling onto the second material compaction device.

[0024] As a preferred embodiment of the present invention, the second inlet is arranged opposite to the opening of the horizontal pipe.

[0025] As a preferred embodiment of the present invention, there are four quartz sand bins, and the particle size distribution ranges stored in the four quartz sand bins are 0~100μm, 100~400μm, 400~700μm and 700~1000μm, respectively.

[0026] As a preferred embodiment of the present invention, the regulating device includes a discharge pipe, a discharge pipe valve, a feeder, and a conveying pipe. The material inlet of the feeder is connected to each of the quartz sand bins through the discharge pipe. The discharge pipe valve is installed on the discharge pipe. The material outlet of the feeder is connected to the riser through the conveying pipe. When adjusting the solid circulation flow rate, the discharge pipe valve is controlled to feed quartz sand of the required particle size into the feeder, which then feeds it into the riser through the conveying pipe, and further into the furnace body through the return foot pipe and the return valve.

[0027] The circulating fluidized bed solid circulation rate adjustment system based on average particle size provided by this invention has the following advantages compared with the prior art:

[0028] This invention obtains the measured value of the solid circulation flow rate during the operation of the circulating fluidized bed through a solid circulation flow rate measuring device, and obtains the resistance of the solid particles after compaction through a solid particle size measuring device. By comparing the resistance characteristic curve of the solid particles, the average particle size of the solid particles is obtained. By comparing the measured solid circulation flow rate, if the measured value of the solid circulation flow rate is within the required operating range, no adjustment is made. If the measured value of the solid circulation flow rate is not within the required operating range and the average particle size of the solid particles is greater than or less than the set value, the discharge rate of each quartz sand bin is controlled to increase fine or coarse particles, thereby changing the average particle size of the solid particles in the circulating fluidized bed and thus adjusting the solid circulation flow rate. This achieves control over the load changes of the circulating fluidized bed boiler, efficiently and directly solving the problem of solid circulation flow rate adjustment in circulating fluidized beds, with fast response and excellent effect. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0030] Figure 1 This is a schematic diagram of the structure of the circulating fluidized bed solid circulation flow rate adjustment system based on average particle size provided in an embodiment of the present invention.

[0031] Figure 2 This is a flowchart of the adjustment process for the circulating fluidized bed solid circulation rate adjustment system based on average particle size in an embodiment of the present invention.

[0032] Marked in the image:

[0033] Furnace body 1; Cyclone separator 2; Riser 3; Return pipe 4; First vertical pipe section 41; Return valve 5; Measuring device 6; Measuring tube 61; First gate 63; Second gate 62; First material control gate 64; Level gauge 65; Second material control gate 66; First differential pressure gauge 67; Second differential pressure gauge 68; First material compaction device 69; Second material compaction device 610; Second vertical pipe section 611; Horizontal pipe 612; First inlet 613; Second inlet 614; Storage device 7; Quartz sand bin 71; Adjusting device 8; Drop pipe 81; Drop pipe valve 82; Feeder 83; Conveying pipe 84. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0036] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0038] Please refer to the following: Figure 1 and Figure 2 The circulating fluidized bed solid circulation rate adjustment system based on average particle size provided in the embodiments of the present invention will now be described.

[0039] like Figure 1As shown in the preferred embodiment of the present invention, a circulating fluidized bed solid circulation flow rate adjustment system based on average particle size includes a furnace body 1, a cyclone separator 2, a measuring device 6 (including a solid circulation flow rate measuring device and a solid particle size measuring device), a storage device 7, and an adjustment device 8. The flue gas inlet of the cyclone separator 2 is connected to the flue gas outlet of the furnace body 1, and the discharge port of the cyclone separator 2 is connected to the return inlet of the furnace body 1 in sequence through a riser 3, a return foot pipe 4, and a return valve 5. The solid circulation flow rate measuring device and the solid particle size measuring device are both arranged between the lower end of the riser 3 and the inlet end of the return valve 5. The storage device 7 consists of multiple quartz sand bins 71, which respectively store quartz sand with different particle size distribution ranges. The adjustment device 8 is connected between the storage device 7 and the riser 3.

[0040] like Figure 2 As shown, the adjustment steps for the corresponding circulating fluidized bed solid circulation rate adjustment system are as follows:

[0041] First, the solid circulation rate during the operation of the circulating fluidized bed is measured using a solid circulation rate measuring device;

[0042] Secondly, the resistance of the solid particles after compaction in the measuring tube is measured by a solid particle size measuring device, and the average particle size of the solid particles is obtained by comparing it with the resistance characteristic curve of the solid particles.

[0043] Finally, the measured solid circulation flow rate and the average particle size of the solid particles are compared. If the measured solid circulation flow rate is within the operating requirements range, no adjustment is made. If the measured solid circulation flow rate is outside the operating requirements range and the average particle size of the solid particles is greater than or less than the set value, the discharge rate of each quartz sand bin 71 is controlled by the adjusting device 8 to increase the amount of fine or coarse particles, and the measured solid circulation flow rate is repeatedly measured until the current measured solid circulation flow rate is within the operating requirements range, at which point the solid circulation flow rate adjustment ends. Thus, by increasing the amount of fine or coarse particles, the particle size of the solid particles in the circulating fluidized bed is changed, thereby adjusting the solid circulation flow rate and achieving control over the load changes of the circulating fluidized bed boiler. This efficiently and directly solves the problem of solid circulation flow rate adjustment in circulating fluidized beds, with fast response and excellent results.

[0044] For example, the solid circulation flow rate measuring device includes a measuring tube 61, a first gate valve 63, a second gate valve 62, a first material control valve 64, and a level gauge 65; the upper end of the measuring tube 61 and the upper end of the return pipe 4 are respectively connected to the lower end of the riser 3 to form a three-way pipe structure; the return pipe 4 has a first vertical pipe section 41, the lower end of the first vertical pipe section 41 is connected to the inlet end of the return valve 5; the measuring tube 61 has a second vertical pipe section 611, the lower end of the second vertical pipe section 611 is connected to the return valve 5 through a horizontal pipe 612. The inlet end is connected; the first gate valve 63 is located at the upper end of the return foot pipe 4, and is used to block the path of solid material flowing from the riser pipe 3 to the return foot pipe 4; the second gate valve 62 is located at the upper end of the measuring pipe 61, and is used to block the path of solid material flowing from the riser pipe 3 to the measuring pipe 61; the first material control gate 64 is located at the connection between the measuring pipe 61 and the horizontal pipe 612, and is used to block the path of solid material flowing from the measuring pipe 61 to the return valve 5; the level gauge 65 is located at the upper end of the second vertical pipe section 611.

[0045] When measuring the solid circulation flow rate, close the first gate valve 63 and the first material control gate 64, open the second gate valve 62 and start timing; after 10 seconds, open the first gate valve 63 and close the second gate valve 62 at the same time to ensure that the solid material passes through the return leg normally and falls into the return valve; record the material level height displayed by the level gauge 65, and calculate the measured value of the solid circulation flow rate under the current operating conditions according to the solid circulation flow rate calculation formula.

[0046] The formula for calculating the solid circulation flow rate is as follows:

[0047] G s =ρ s *π*D 2 *h / 40;

[0048] Among them, G s Let ρ be the solid circulation flow rate. s The bulk density of the solid material under operating conditions (determined in the laboratory), D is the diameter of the measuring tube 61, and h is the material level height measured by the level gauge 65.

[0049] It should be noted that the solid circulation flow rate measuring device of the circulating fluidized bed solid circulation flow rate adjustment system in this embodiment, through the organic combination of measuring tube 61, first gate 63, second gate 62, first material control gate 64, and level gauge 65, and based on the solid circulation flow rate calculation formula, directly uses the material level height to obtain the measured value of the solid circulation flow rate under the current operating conditions, thereby reliably realizing the measurement of the solid circulation flow rate of the circulating fluidized bed. The measuring facility is simple, easy to operate, has stable performance, and is low in cost.

[0050] For example, the solid particle size measuring device includes a measuring tube 61, a first gate valve 63, a second gate valve 62, a first material control gate 64, a second material control gate 66, a first differential pressure gauge 67, a second differential pressure gauge 68, a first material compaction device 69, and a second material compaction device 610; the upper end of the measuring tube 61 and the upper end of the return pipe 4 are respectively connected to the lower end of the riser 3 to form a three-way pipe structure; the return pipe 4 is provided with a first vertical pipe section 41, and the lower end of the first vertical pipe section 41 is connected to the... The inlet end of the return valve 5 is connected to the measuring tube 61, which has a second vertical pipe section 611. The lower end of the second vertical pipe section 611 is connected to the inlet end of the return valve 5 via a horizontal pipe 612. The first gate valve 63 is located at the upper end of the return foot pipe 4 and is used to block the flow of solid material from the riser 3 to the return foot pipe 4. The second gate valve 62 is located at the upper end of the measuring tube 61 and is used to block the flow of solid material from the riser 3 to the measuring tube 61. The first material control gate 64 is provided with... A first material control valve 64 is positioned at the connection between the measuring tube 61 and the horizontal tube 612 to allow solid material to flow from the measuring tube 61 to the return valve 5. A second material control valve 66 is positioned on the horizontal tube 612 to allow solid material to flow from the measuring tube 61 to the return valve 5. A first material compaction device 69 and a second material compaction device 610 are spaced apart on the second vertical tube section 611, and both the first material compaction device 69 and the second material compaction device 610 are provided with a material gate for allowing the measuring tube 61 to flow. A first differential pressure gauge 67 is positioned on the measuring tube 61 and above the first material compaction device 69. A second differential pressure gauge 68 is positioned on the horizontal tube 612 and between the first material control valve 64 and the second material control valve 66. A first inlet 613 for particle size measuring air input is provided on the side of the measuring tube 61 near the second gate valve 62. A second inlet 614 for solid backflushing air input is provided at the lower end of the measuring tube 61.

[0051] When measuring solid particle size, the first gate valve 63, the first material control valve 64, and the second material control valve 66 are closed, and the second gate valve 62 is opened, allowing solid material to flow into the measuring tube 61; the material gate of the first material compaction device 69 is opened, and the valve of the second material compaction device 610 is closed; after the weight of the material entering the measuring tube 61 meets the set value, the first gate valve 63 is opened, and the second gate valve 62 is closed simultaneously to ensure that the solid material passes normally through the return leg and falls into the return valve; the material gate of the first material compaction device 69 is closed, and the first material compaction device 69 and the second material compaction device 610 are operated to compact the material; through the first The particle size measuring air is connected to the inlet 613, and the pressure shown by the first differential pressure gauge 67 and the second differential pressure gauge 68 is recorded to obtain the resistance of the solid particles after compaction. The fitting curve of the material resistance and the average particle size of the solid particles is compared with the pre-established curve to obtain the average particle size of the solid material. The particle size measuring air is turned off, and the material gates of the first material compaction device 69, the second material compaction device 610, the first material control gate 64, and the second material control gate 66 are opened. The solid back-blowing air is connected through the second inlet 614 to transport the solid material in the measuring tube 61 to the return valve. The second material control gate 66 is closed, and the solid particle size measurement ends.

[0052] The fitting curve between the material resistance and the average particle size of the solid particles is established in advance through the following steps:

[0053] Step 1: Take a certain mass of solid material from the boiler during operation, sieve it, and group the solid material into groups with a group spacing of 50μm. The mass of each group of solid material is equal to the material mass setting value of the solid particle size measuring device.

[0054] Step 2: Measure the average particle size of different groups of solid materials of the same mass;

[0055] Step 3: Load different groups of solid materials into the measuring tube and measure the resistance of particles of each size;

[0056] Step 4: Plot the resistance of each particle size measured in Step 3 against the average particle size of the solid material measured in Step 2 on graph paper, and fit the graph to obtain the fitting curve of the material resistance versus the average particle size of the solid particles.

[0057] It should be noted that the solid particle size measuring device belonging to the circulating fluidized bed solid circulation flow rate adjustment system of this embodiment, through the organic combination of measuring tube 61, first gate 63, second gate 62, first material control gate 64, second material control gate 66, first differential pressure gauge 67, second differential pressure gauge 68, first material compaction device 69 and second material compaction device 610, can compact the material in the measuring tube 61 and measure the resistance of solid particles. By comparing the pre-established fitting curve of material resistance and average particle size of solid particles, the average particle size of solid material during operation can be analyzed and obtained. Thus, the average particle size of solid material in circulating fluidized bed can be reliably measured. The measuring facility is simple, easy to operate, stable in performance and low in cost.

[0058] It is understood that the measuring tube 61, the first gate 63, the second gate 62, and the first material control gate 64 are all shared facilities for the solid circulation flow rate measuring device and the solid particle size measuring device. While reducing the cost of the measuring facilities, they can realize the measurement of solid circulation flow rate and the measurement of the average particle size of solid materials in the same measuring tube, with a reasonable and compact structure.

[0059] For example, the second material compaction device 610 is equipped with a weighing sensor (not shown in the figure) to measure the weight of solid material falling onto the second material compaction device 610. When the weight of the material entering the measuring tube meets the set value, the material gate of the first material compaction device 69 can be controlled to close for convenient operation.

[0060] For example, the second inlet 614 is arranged opposite to the opening of the horizontal pipe 612 to ensure that the air force of the solid back-blowing can directly act on the material and push it toward the furnace body 1.

[0061] For example, there are four quartz sand bins 71, and the particle size distribution ranges stored in the four quartz sand bins 71 are 0~100μm, 100~400μm, 400~700μm and 700~1000μm, respectively.

[0062] For example, the regulating device 8 includes a discharge pipe 81, a discharge pipe valve 82, a feeder 83, and a conveying pipe 84. The material inlet of the feeder 83 is connected to each of the quartz sand bins 71 through the discharge pipe 81. The discharge pipe valve 82 is installed on the discharge pipe 81. Each quartz sand bin 71 corresponds to one discharge pipe 81 and one discharge valve. The material outlet of the feeder 83 is connected to the riser 3 through the conveying pipe 84. When adjusting the solid circulation flow rate, the discharge pipe valve 82 is controlled to send quartz sand of the required particle size into the feeder 83, through the conveying pipe 84 into the riser 3, and further through the return foot pipe 4 and the return valve 5 into the furnace body 1.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A circulating fluidized bed solids circulation rate adjustment system based on average particle size, comprising a furnace body and a cyclone separator, a flue gas inlet of the cyclone separator being connected with a flue gas outlet of the furnace body, a discharge port of the cyclone separator being connected with a return material inlet of the furnace body in sequence through a standpipe, a return material foot pipe and a return material valve; characterized in that, Also includes: A solid circulation flow rate measuring device is arranged between the lower end of the riser and the inlet end of the return valve, and is used to measure the solid circulation flow rate during the operation of the circulating fluidized bed. A solid particle size measuring device is arranged between the lower end of the riser and the inlet end of the return valve. It is used to measure the resistance of solid particles after compaction in the measuring pipe, compare it with the resistance characteristic curve of the solid particles, and analyze to obtain the average particle size of the solid particles. The storage device consists of multiple quartz sand bins, each used to store quartz sand with a different particle size distribution range. An adjustment device is connected between the storage device and the riser. It is used to control the discharge rate of each quartz sand bin, increase fine or coarse particles, and change the average particle size of solid particles in the circulating fluidized bed when the measured value of the solid circulation flow rate is not within the operating requirement range and the average particle size of the solid particles is greater than or less than the set value, thereby adjusting the solid circulation flow rate. The solid particle size measuring device includes a measuring tube, a first gate, a second gate, a first material control gate, a second material control gate, a first differential pressure gauge, a second differential pressure gauge, a first material compaction device, and a second material compaction device. The upper end of the measuring tube and the upper end of the return foot tube are respectively connected to the lower end of the vertical pipe to form a three-way pipe structure. The return foot tube is provided with a first vertical pipe section, the lower end of the first vertical pipe section is connected to the inlet end of the return valve, and the measuring tube is provided with a second vertical pipe section, the lower end of the second vertical pipe section is connected to the inlet end of the return valve through a horizontal pipe. The first gate valve is located at the upper end of the return foot pipe, used to block the path of solid material flowing from the riser to the return foot pipe; the second gate valve is located at the upper end of the measuring pipe, used to block the path of solid material flowing from the riser to the measuring pipe; the first material control valve is located at the connection between the measuring pipe and the horizontal pipe, used to block the path of solid material flowing from the measuring pipe to the return valve; the second material control valve is located on the horizontal pipe, used to block the path of solid material flowing from the measuring pipe to the return valve; the first material compaction device and The second material compaction device is spaced apart on the second vertical pipe section. Both the first and second material compaction devices are equipped with material gates for opening and closing the measuring pipe. The first differential pressure gauge is installed on the measuring pipe and located above the first material compaction device. The second differential pressure gauge is installed on the horizontal pipe and located between the first material control gate and the second material control gate. The measuring pipe has a first inlet for particle size measuring air input on the side near the second gate. The lower end of the measuring pipe has a second inlet for solid backflushing air input. When measuring solid particle size, close the first gate valve, the first material control valve, and the second material control valve, and open the second gate valve to allow solid material to flow into the measuring tube. Open the material gate of the first material compaction device and close the valve of the second material compaction device. After the weight of the material entering the measuring tube meets the set value, open the first gate valve and simultaneously close the second gate valve to ensure that the solid material passes normally through the return leg and falls into the return valve. Close the material gate of the first material compaction device and operate the first and second material compaction devices to compact the material. Connect the particle size measuring air and record the pressure shown by the first and second differential pressure gauges to obtain the resistance of the solid particles after compaction. Compare the pre-established fitting curve of material resistance and average particle size of solid particles to analyze and obtain the average particle size of the solid material. Close the particle size measuring air and open the material gates of the first and second material compaction devices, the first material control valve, and the second material control valve. Connect the solid back-blowing air to transport the solid material in the measuring tube to the return valve. Close the second material control valve, and the solid particle size measurement ends.

2. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The solid circulation flow rate measuring device includes a measuring tube, a first gate, a second gate, a first material control gate, and a level gauge; The upper ends of the measuring tube and the return material foot tube are respectively connected to the lower end of the riser to form a three-way pipe structure. The return material foot tube has a first vertical pipe section, the lower end of which is connected to the inlet end of the return material valve. The measuring tube has a second vertical pipe section, the lower end of which is connected to the inlet end of the return material valve through a horizontal pipe. The first gate valve is located at the upper end of the return material foot tube and is used to block the path of solid material flowing from the riser to the return material foot tube. The second gate valve is located at the upper end of the measuring tube and is used to block the path of solid material flowing from the riser to the measuring tube. The first material control valve is located at the connection between the measuring tube and the horizontal pipe and is used to block the path of solid material flowing from the measuring tube to the return material valve. The level gauge is located at the upper end of the second vertical pipe section. When measuring the solid circulation flow rate, close the first gate and the first material control gate, open the second gate and start timing; after 10 seconds, open the first gate and close the second gate at the same time to ensure that the solid material passes through the return leg normally and falls into the return valve; record the material level height displayed by the level gauge, and calculate the measured value of the solid circulation flow rate under the current operating conditions according to the solid circulation flow rate calculation formula.

3. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The formula for calculating the solid circulation flow rate is as follows: G s =ρ s *π*D 2 *h / 40; where G s is the solids circulation rate, p s is the bulk density of the solids material under operating conditions, D is the diameter of the measuring tube, and h is the level height measured by the level meter.

4. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The fitting curve between the material resistance and the average particle size of the solid particles is established in advance through the following steps: Step 1: Take a certain mass of solid material from the boiler during operation, sieve it, and group the solid material into groups with a group spacing of 50μm. The mass of each group of solid material is equal to the material mass setting value of the solid particle size measuring device. Step 2: Measure the average particle size of different groups of solid materials of the same mass; Step 3: Load different groups of solid materials into the measuring tube and measure the resistance of particles of each size; Step 4: Plot the resistance of each particle size measured in Step 3 against the average particle size of the solid material measured in Step 2 on graph paper, and fit the graph to obtain the fitting curve of the material resistance versus the average particle size of the solid particles.

5. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The second material compaction device is equipped with a weighing sensor to measure the weight of solid material falling onto the second material compaction device.

6. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The second inlet is arranged opposite to the opening of the horizontal pipe.

7. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The quartz sand bins are provided with four bins, and the particle size distribution ranges stored in the four quartz sand bins are 0~100μm, 100~400μm, 400~700μm and 700~1000μm, respectively.

8. The average particle diameter-based circulating fluidized bed solids circulation rate adjustment system according to claim 1, characterized by, The regulating device includes a discharge pipe, a discharge pipe valve, a feeder, and a conveying pipe. The material inlet of the feeder is connected to each of the quartz sand bins through the discharge pipe. The discharge pipe valve is installed on the discharge pipe. The material outlet of the feeder is connected to the riser through the conveying pipe. When adjusting the solid circulation flow rate, control the discharge pipe valve to send the required particle size of quartz sand into the feeder, through the conveying pipe into the riser, and further through the return foot pipe and return valve into the furnace body.

Images