Method for reducing the content of oil gas dust at the outlet of a rotary pyrolysis kiln

Abstract

This invention relates to the field of pulverized coal pyrolysis technology, and more particularly to a method for reducing the dust content in the oil and gas at the outlet of a rotary pyrolysis kiln. The method includes collecting particle size distribution data of the pulverized coal raw material and the initial operating parameters of the rotary pyrolysis kiln; identifying the proportion of small-particle-size pulverized coal based on the data and calculating the dust emission tendency value within the kiln; adjusting the kiln structure parameters according to the dust emission tendency value, including extending the kiln length and reducing the kiln rotation speed to reduce the material drop height; subsequently optimizing the oil and gas output path by changing the raw coal gas outlet location to a gas collection chamber above the kiln head hood and increasing the initial pipe diameter of the gas collection chamber outlet to promote gravity settling; and installing a gradually decreasing diameter inclined gas outlet pipe in the rising section of the oil and gas to increase the flow velocity and promote dust transport. This invention significantly reduces the dust content in the outlet oil and gas through multi-stage control, avoids pipeline blockage, and improves product quality.

Description

Technical Field

[0001] This invention relates to the field of pulverized coal pyrolysis technology, and in particular to a method for reducing the content of oil, gas and dust at the outlet of a rotary pyrolysis kiln. Background Technology

[0002] In the industrial production of clean coal, tar, and coal gas from low-temperature pyrolysis of pulverized coal, a rotary pyrolysis kiln is a continuous pyrolysis device with a rotating kiln body design. The rotation of the kiln body allows the pulverized coal to be heated uniformly at low temperatures, promoting the decomposition of organic matter in the coal into oil, gas, and solid products. The outlet oil and gas refers to the gaseous and liquid mixture produced during the pyrolysis process, mainly including coal gas and tar, which is discharged through the kiln tail into the subsequent processing system. The dust content indicates the concentration of solid particles entrained in the oil and gas flow, which comes from the physical entrainment of fine pulverized coal particles or pyrolysis residues. Excessive dust content may clog pipelines, aggravate equipment wear, and affect the oil and gas separation efficiency.

[0003] Existing low-temperature pyrolysis technology for pulverized coal suffers from the following technical challenges: In industrial production scenarios where pulverized coal is pyrolyzed to produce clean coal, tar, and coal gas, the high rotation speed of existing rotary pyrolysis kilns when processing small-particle pulverized coal causes materials to be frequently stirred up within the kiln, resulting in oil and gas containing large amounts of dust. This high dust content in the oil and gas easily accumulates in pipelines after output, causing blockages and increasing equipment maintenance burden. Simultaneously, dust mixes into the low-temperature coal tar product, complicating the oil-dust separation process, reducing tar purity, and impacting product market value. For example, in continuous production lines, pipeline blockages can lead to unplanned downtime, reducing production efficiency, while deteriorating tar quality directly results in a decline in sales prices, harming overall economic benefits. The root cause lies in the mismatch between rotary kiln operating parameters and pulverized coal characteristics, insufficient dust control, and consequently, a series of production obstacles. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for reducing the dust content in the oil and gas at the outlet of a rotary pyrolysis kiln. This method solves the technical problems of pipeline blockage, decreased tar quality, and low economic efficiency caused by material dust generated by the high-speed rotation of the rotary kiln during pulverized coal pyrolysis, resulting in a large amount of dust (250-270 g / Nm³) carried by the oil and gas at the outlet.

[0005] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows: This invention provides a method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln, comprising: Collect particle size distribution data of pulverized coal raw materials and initial operating parameters of the rotary pyrolysis kiln, including kiln rotation speed, kiln length and gas outlet pipe diameter; Using the particle size distribution data and the initial operating parameters as input, the characteristic of a high proportion of small-particle-size pulverized coal is identified, and the dust emission tendency of the material in the rotary pyrolysis kiln is calculated. Based on the value of the dust tendency, the structural parameters of the rotary pyrolysis kiln are adjusted. The adjustment of the structural parameters includes extending the kiln length and setting the kiln rotation speed from - rpm to rpm to reduce the material drop height. After adjusting the structural parameters, the oil and gas output path is optimized. The optimization of the oil and gas output path includes changing the raw coal gas outlet location to the gas collection chamber above the kiln head hood and expanding the initial pipe diameter of the gas collection chamber outlet. After optimizing the oil and gas output path, a gas outlet inclined pipe is set in the rising section of the oil and gas, and the diameter of the gas outlet inclined pipe gradually decreases along the flow direction. By adjusting structural parameters, optimizing the oil and gas output path, and setting up an inclined gas outlet pipe, the dust content of the outlet oil and gas was reduced.

[0006] Furthermore, in the method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention, the step of collecting particle size distribution data of pulverized coal raw material includes: The weight distribution of particles of different sizes was obtained by processing pulverized coal samples using sieve analysis. Based on the obtained weight distribution, calculate the cumulative mass percentage of particles with a particle size smaller than a preset threshold; The calculated cumulative mass percentage is used as a characteristic value representing the proportion of small-diameter pulverized coal in the particle size distribution data.

[0007] Furthermore, in the method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention, the calculation of the dust-generating tendency of the material within the rotary pyrolysis kiln includes: A kinematic model of material movement inside a rotary pyrolysis kiln is constructed. The input parameters of the kinematic model include the kiln rotation speed and particle size distribution data. The kinematic model was constructed to simulate the motion trajectory of pulverized coal particles in a rotary pyrolysis kiln under different kiln rotation speeds. The throwing height and throwing frequency of the material were extracted from the simulated motion trajectory. The extracted scattering height and scattering frequency are multiplied together, and the result is quantified as a value indicating dust tendency.

[0008] Furthermore, in the method for reducing the oil, gas, and dust content at the outlet of a rotary pyrolysis kiln according to the present invention, adjusting the structural parameters of the rotary pyrolysis kiln includes: Compare the dust emission tendency value with the preset safety threshold; When the comparison results show that the dust emission tendency value exceeds the safety threshold, the kiln length is extended and the kiln rotation speed is set from - rpm to rpm. Extending the kiln length increases the residence time of pulverized coal pyrolysis; setting the kiln rotation speed to a certain value per minute changes the material movement mode from a throwing mode to a rolling mode.

[0009] Furthermore, in the method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention, the optimization of the oil and gas output path includes: A gas collection chamber is installed on the upper part of the kiln head cover to transfer the outlet point of the raw coal gas from the kiln tail to the gas collection chamber. Set an initial output pipe section leading from the installed gas collection chamber, and design the diameter of the initial output pipe section to be larger than the diameter of the gas outlet pipe located at the kiln tail in the background technology. The increased pipe diameter causes the gas velocity of raw coal gas flowing through the initial output pipe section to be lower than the gravity settling boundary velocity. Due to the reduced flow velocity and gravity, large-diameter dust particles with a density greater than that of oil and gas settle in the initial output pipe section.

[0010] Furthermore, the method for reducing the dust content of oil and gas at the outlet of a rotary pyrolysis kiln according to the present invention, wherein the inclined tube structure is provided in the rising section of the oil and gas includes: A gas outlet inclined pipe is installed, with its inlet connected to the initial output pipe section. The axis of the gas outlet inclined pipe extends upward at an acute angle to the horizontal plane. The diameter of the inclined pipe at the gas outlet decreases continuously or in segments from the inlet to the outlet; The reduction in pipe diameter reduces the cross-sectional area of ​​the raw coal gas flowing through the inclined pipe of the coal gas outlet, causing the raw coal gas flow velocity to increase above the critical conveying velocity. This flow velocity carries dust towards the cyclone dust collector connected to the outlet of the inclined pipe of the coal gas outlet.

[0011] Furthermore, the method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention further includes: The gas flow velocity of the raw coal gas flowing through the inclined gas outlet pipe increases to above the critical conveying velocity. This high velocity causes some of the dust that cannot be carried away to slide back to the kiln head hood along the inclined pipe wall inside the gas outlet pipe.

[0012] Furthermore, in the method for reducing the oil, gas, and dust content at the outlet of a rotary pyrolysis kiln according to the present invention, adjusting the structural parameters of the rotary pyrolysis kiln includes: When the dust emission tendency value exceeds the safety threshold, the kiln rotation speed is set to . revolutions / minute, and the kiln length is set to meters; The kiln rotation speed is set to . revolutions per minute and the kiln length is set to . meters. Together, these settings cause the movement of pulverized coal in the rotary pyrolysis kiln to change to a rolling mode and reduce the material spillage height.

[0013] Furthermore, the method for reducing the oil and gas dust content at the outlet of the rotary pyrolysis kiln described in this invention, after adjusting structural parameters to suppress dust generation, optimizes the oil and gas output path and sets up an inclined tube structure in the oil and gas rising section: After dust generation is suppressed, the raw coal gas exported from the gas collection chamber enters the initial output pipe section with an enlarged diameter. The flow velocity is lower than the gravity settling threshold flow velocity, so that medium and large-diameter dust particles are separated in the initial output pipe section by gravity settling. The raw coal gas, after passing through the initial output pipe section, then enters the inclined gas outlet pipe. The reduced diameter of the inclined gas outlet pipe increases the flow rate of the raw coal gas to above the critical conveying speed. This flow rate carries the remaining fine dust into the cyclone dust collector.

[0014] Furthermore, the method for reducing the dust content of oil and gas at the outlet of a rotary pyrolysis kiln described in this invention optimizes the oil and gas output path and sets up an inclined tube structure to form a dust control sequence in sequence: In the first stage, the diameter of the initial output pipe section is increased, and the gas flow velocity of the raw coal gas flowing out of the gas collection chamber is controlled to be lower than the gravity settling threshold velocity. The low flow velocity environment allows dust particles with a high settling rate to be separated by gravity settling. In the second stage, the raw coal gas enters the inclined pipe at the gas outlet. The inclination angle and gradually decreasing diameter of the inclined pipe increase the flow rate of the raw coal gas to above the critical conveying speed. The flow rate above the critical conveying speed relies on fluid dynamics to prevent dust deposition and transport the dust to the dust collector.

[0015] The beneficial effects of this invention are: This invention establishes a quantitative model of dust generation tendency by collecting data on the particle size distribution of pulverized coal and kiln operating parameters. Based on the model results, the length and rotation speed parameters of the kiln are adjusted to change the material movement mode from scattering to rolling, thus suppressing dust generation at the source. By optimizing the outlet location of raw coal gas to the gas collection chamber at the top of the kiln head and expanding the initial pipe diameter, a low-speed settling environment is created to achieve efficient separation of large-particle dust. Combined with an inclined variable-diameter pipe structure, precise flow velocity control is achieved, forming a multi-stage dust removal sequence with the synergistic effect of gravity settling and fluid transport. Ultimately, this significantly improves the purity of tar products while reducing the risk of pipeline blockage, effectively solving the problems of equipment wear and low economic efficiency caused by high dust content. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0017] Figure 1 This is a partial schematic diagram of the process flow of the present invention.

[0018] Figure 2 Side view of the waste heat boiler of the present invention.

[0019] Figure 3 : Front view of the waste heat boiler of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 1. Hopper; 2. Screw feeder; 3. Nitrogen inlet; 4. Flue gas outlet; 5. Flue gas hood; 6. Rotary pyrolysis kiln body; 7. Rotary pyrolysis kiln drive unit; 8. Radiant tube; 9. Hot air hood; 10. Kiln head hood; 11. Waste heat boiler; 12. Discharge port; 13. Hot air furnace; 14. Gas outlet pipe. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The technical solutions provided by various embodiments of this invention will be described in detail below with reference to the accompanying drawings.

[0022] To better understand the purpose of this invention, the invention will now be described in further detail.

[0023] Please see Figures 1 to 3 The present invention provides a method for reducing the content of oil and gas dust at the outlet of a rotary pyrolysis kiln, comprising: Collect particle size distribution data of pulverized coal raw materials and initial operating parameters of rotary pyrolysis kiln 6, including kiln rotation speed, kiln length and gas outlet pipe diameter; Using the particle size distribution data and the initial operating parameters as input, the characteristic of a high proportion of small-particle-size pulverized coal is identified, and the dust emission tendency of the material in the rotary pyrolysis kiln 6 is calculated. Based on the value of the dust tendency, the structural parameters of the rotary pyrolysis kiln 6 are adjusted. The adjustment of the structural parameters includes extending the kiln length and setting the kiln rotation speed from 2-3 rpm to 1.5 rpm to reduce the material drop height. After adjusting the structural parameters, the oil and gas output path is optimized. The optimization of the oil and gas output path includes changing the raw coal gas outlet location to the gas collection chamber 15 on the upper part of the kiln head hood 10, and expanding the initial pipe diameter of the outlet of the gas collection chamber 15. After optimizing the oil and gas output path, a gas outlet inclined pipe 16 is set in the oil and gas rising section, and the diameter of the gas outlet inclined pipe 16 gradually decreases along the flow direction. By adjusting structural parameters, optimizing the oil and gas output path, and setting the gas outlet inclined pipe 16, the dust content of the outlet oil and gas was reduced.

[0024] This invention relates to a method for reducing the dust content in the oil and gas at the outlet of a rotary pyrolysis kiln. This method achieves effective dust control by systematically analyzing the characteristics of pulverized coal and the kiln's operating parameters, and then specifically adjusting the equipment structure and oil and gas pathways. The method begins by collecting particle size distribution data of the pulverized coal raw material. Specifically, pulverized coal samples are processed using sieving analysis to obtain the weight distribution of particles of different sizes, and the cumulative mass percentage of small-diameter particles is calculated as a key indicator characterizing the raw material's properties. Simultaneously, initial operating parameters of the rotary pyrolysis kiln 6 are collected, including kiln rotation speed, kiln length, and outlet pipe diameter, providing a basis for subsequent dust assessment. This step ensures that subsequent adjustments are based on actual production data, enhancing the applicability of the solution.

[0025] Based on the collected particle size distribution data and initial operating parameters, the method proceeds to the dust emission tendency calculation stage. A kinematic model of material movement within the rotary pyrolysis kiln (6) is constructed to simulate the trajectory of pulverized coal particles within the kiln. The material's throwing height and frequency are extracted from the trajectory, and their product is quantified as a dust emission tendency value. This value is used to identify the risk characteristic of a high proportion of small-diameter pulverized coal, thereby predicting the dust emission intensity within the kiln and providing a quantitative basis for adjusting structural parameters.

[0026] Based on the dust emission tendency values, the method further adjusts the structural parameters of the rotary pyrolysis kiln 6. When the values ​​exceed the preset safety threshold, the kiln length is extended and the kiln rotation speed is reduced, for example, by setting the rotation speed from a higher range to a lower value. Increasing the kiln length prolongs the residence time of pulverized coal pyrolysis, while reducing the rotation speed causes the material movement mode to change from scattering to rolling, reducing the material drop height and thus suppressing dust generation. This adjustment directly targets the root cause of dust emission and improves the operational stability within the kiln.

[0027] Based on structural parameter adjustments, the method optimizes the oil and gas output path. The outlet location of the raw coal gas is shifted from the kiln tail to the gas collection chamber 15 above the kiln head hood 10, and the initial pipe diameter of the outlet of the gas collection chamber 15 is enlarged. Enlarging the pipe diameter reduces the raw coal gas flow velocity, making it lower than the gravity settling boundary velocity, thus utilizing gravity to cause large-diameter dust particles to settle and separate in the initial output pipe section. This step utilizes physical principles to achieve preliminary dust removal, reducing the load on subsequent processing.

[0028] After optimizing the oil and gas output path, the method involves installing a gas outlet inclined pipe 16 in the rising section of the oil and gas pipeline. The inlet of the gas outlet inclined pipe 16 connects to the initial output pipe section, and its axis extends upwards at an acute angle to the horizontal plane, with the pipe diameter gradually decreasing along the flow direction. The reduced pipe diameter increases the raw coal gas flow velocity to above the critical conveying velocity, relying on hydrodynamics to prevent dust deposition and carry the dust to the cyclone dust collector; simultaneously, the inclined design allows any uncarried dust to slide back along the pipe wall to the kiln head hood 10, avoiding pipe blockage. This step, combining flow rate control and structural design, improves dust conveying efficiency.

[0029] By combining the above steps, the method forms a multi-stage dust control sequence: structural parameter adjustment suppresses dust sources, oil and gas path optimization achieves gravity settling, and inclined pipe structure promotes efficient transportation. Ultimately, the dust content of the oil and gas at the outlet is significantly reduced, improving pipeline flowability and tar product quality, and enhancing production economics.

[0030] Specifically, the method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention includes, in the case of collecting particle size distribution data of pulverized coal raw materials, the following steps: The weight distribution of particles of different sizes was obtained by processing pulverized coal samples using sieve analysis. Based on the obtained weight distribution, calculate the cumulative mass percentage of particles with a particle size smaller than a preset threshold; The calculated cumulative mass percentage is used as a characteristic value representing the proportion of small-diameter pulverized coal in the particle size distribution data.

[0031] The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention, wherein calculating the dust-generating tendency of the material within the rotary pyrolysis kiln 6 includes: A kinematic model of material movement within the rotary pyrolysis kiln 6 was constructed. The input parameters of the kinematic model included the kiln rotation speed and particle size distribution data. The kinematic model was constructed to simulate the motion trajectory of pulverized coal particles in the rotary pyrolysis kiln 6 under different kiln rotation speeds. The throwing height and throwing frequency of the material were extracted from the simulated motion trajectory. The extracted scattering height and scattering frequency are multiplied together, and the result is quantified as a value indicating dust tendency.

[0032] The method for reducing the oil, gas, and dust content at the outlet of a rotary pyrolysis kiln according to the present invention, wherein adjusting the structural parameters of the rotary pyrolysis kiln 6 includes: Compare the dust emission tendency value with the preset safety threshold; When the comparison results show that the dust emission tendency value exceeds the safety threshold, the kiln length is extended and the kiln rotation speed is set from 2-3 rpm to 1.5 rpm. Extending the kiln length increases the residence time of pulverized coal pyrolysis; setting the kiln rotation speed to 1.5 rpm changes the material movement mode from a throwing mode to a rolling mode.

[0033] The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention, wherein optimizing the oil and gas output path includes: A gas collection chamber 15 is installed on the upper part of the kiln head cover 10 to transfer the outlet point of the raw coal gas from the kiln tail to the gas collection chamber 15. Set an initial output pipe section leading from the installed gas collection chamber 15, and design the diameter of the initial output pipe section to be larger than the diameter of the gas outlet pipe 14 located at the kiln tail in the background art. The increased pipe diameter causes the gas velocity of raw coal gas flowing through the initial output pipe section to be lower than the gravity settling boundary velocity. Due to the reduced flow velocity and gravity, large-diameter dust particles with a density greater than that of oil and gas settle in the initial output pipe section.

[0034] The method for reducing the dust content of oil and gas at the outlet of a rotary pyrolysis kiln according to the present invention, wherein the inclined tube structure is provided in the rising section of the oil and gas includes: A gas outlet inclined pipe 16 is installed. The inlet of the gas outlet inclined pipe 16 is connected to the initial output pipe section. The axis of the gas outlet inclined pipe 16 extends upward at an acute angle to the horizontal plane. The diameter of the gas outlet inclined pipe 16 decreases continuously or in sections from the inlet to the outlet; The reduction in pipe diameter reduces the cross-sectional area of ​​the raw coal gas flowing through the inclined pipe 16 of the coal gas outlet, causing the raw coal gas flow velocity to increase above the critical conveying velocity. This flow velocity carries dust to the cyclone dust collector connected to the outlet of the inclined pipe 16 of the coal gas outlet.

[0035] The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to the present invention further includes: The gas flow velocity of the raw coal gas flowing through the inclined pipe 16 of the gas outlet increases to above the critical conveying velocity. This high velocity causes some of the dust that cannot be carried away to slide back to the kiln head hood 10 along the inclined pipe wall inside the inclined pipe 16 of the gas outlet.

[0036] The method for reducing the oil, gas, and dust content at the outlet of a rotary pyrolysis kiln according to the present invention, wherein adjusting the structural parameters of the rotary pyrolysis kiln 6 includes: When the dust emission tendency value exceeds the safety threshold, the kiln rotation speed is set to 1.5 revolutions per minute, and the kiln length is set to 55 meters. The kiln rotation speed is set to 1.5 revolutions per minute, and the kiln length is set to 55 meters. This combination causes the movement of pulverized coal in the rotary pyrolysis kiln 6 to change to a rolling mode, and reduces the material spillage height.

[0037] The method for reducing the dust content of oil and gas at the outlet of a rotary pyrolysis kiln, as described in this invention, involves adjusting structural parameters to suppress dust generation, followed by optimizing the oil and gas output path and setting an inclined tube structure in the rising section of the oil and gas. After dust generation is suppressed, the raw coal gas exported from the gas collection chamber 15 enters the initial output pipe section with an enlarged diameter. The flow velocity is lower than the gravity settling threshold flow velocity, so that medium and large-diameter dust particles are separated in the initial output pipe section by gravity settling. The raw coal gas after passing through the initial output pipe section then enters the gas outlet inclined pipe 16. The reduced diameter of the gas outlet inclined pipe 16 increases the raw coal gas flow rate to above the critical conveying speed. This flow rate carries the remaining fine dust into the cyclone dust collector.

[0038] The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln, as described in this invention, optimizes the oil and gas output path and sets up an inclined tube structure to form a dust control sequence in sequence. In the first stage, the diameter of the initial output pipe section is increased, and the gas flow velocity of the raw coal gas flowing out of the gas collection chamber 15 is controlled to be lower than the gravity settling threshold velocity. The low flow velocity environment allows dust particles with a high settling rate to be separated by gravity settling. In the second stage, the raw coal gas enters the inclined pipe 16 at the gas outlet. The inclination angle and gradually decreasing diameter of the inclined pipe 16 increase the flow rate of the raw coal gas to above the critical conveying speed. The flow rate above the critical conveying speed relies on fluid dynamics to prevent dust deposition and transport the dust to the dust collector.

[0039] When collecting particle size distribution data of pulverized coal raw materials, sieving analysis was used to process the pulverized coal samples. This process involves using a standard sieve set to grade and sieve representative pulverized coal samples, separating particles according to particle size using a vibrating sieve device, and then weighing the particles on each sieve to obtain the weight distribution of different particle size ranges. Based on the weight distribution, the cumulative mass percentage of particles with a diameter smaller than a preset threshold was calculated. This threshold was set according to the common dust particle size range. The cumulative mass percentage was obtained by summing the weight percentages of each small particle size range, serving as a characteristic value representing the proportion of small-diameter pulverized coal and providing input data for dust emission tendency calculation.

[0040] To calculate the dust emission tendency of materials within the rotary pyrolysis kiln body 6, a kinematic model of the material movement within the kiln body 6 is constructed. The kinematic model is based on the kiln's geometric parameters and kinematic equations, with input parameters including kiln rotation speed and particle size distribution data. The model simulates the trajectory of pulverized coal particles at different kiln rotation speeds, considering the centrifugal force and gravity during kiln rotation. The material's throwing height and throwing frequency are extracted from the simulated trajectory. Throwing height refers to the height the particles are thrown, and throwing frequency refers to the number of times particles are thrown per unit time. The throwing height and throwing frequency are multiplied, and the result is quantified as a numerical value representing the dust emission tendency, reflecting the degree of dust emission risk.

[0041] The structural parameters of the rotary pyrolysis kiln body 6 are adjusted based on a comparison between the dust emission tendency value and a preset safety threshold. When the dust emission tendency value exceeds the safety threshold, the kiln length is extended and the kiln rotation speed is reduced. Extending the kiln length increases the residence time of pulverized coal in pyrolysis, while reducing the kiln rotation speed changes the material movement mode from a scattering mode to a rolling mode, reducing the material drop height and thus suppressing dust generation. After the structural adjustment, the pulverized coal is more evenly distributed in the kiln, and the pyrolysis process is more stable.

[0042] Optimizing the oil and gas output path involves installing a gas collection chamber 15 on the upper part of the kiln head hood 10, shifting the raw coal gas outlet point from the kiln tail to the gas collection chamber 15. An initial output pipe section is set up from the gas collection chamber 15, with its diameter designed to be larger than the diameter of the coal gas outlet pipe 14 located at the kiln tail in the prior art. The increased pipe diameter causes the raw coal gas flow velocity through the initial output pipe section to be lower than the gravity settling boundary velocity. Due to the reduced flow velocity and gravity, large-diameter dust particles with a density greater than that of oil and gas settle in the initial output pipe section, achieving initial separation.

[0043] The inclined pipe structure installed in the rising section of the oil and gas pipeline includes a gas outlet inclined pipe 16. The inlet of the gas outlet inclined pipe 16 is connected to the initial output pipe section, and the axis of the gas outlet inclined pipe 16 extends upward at an acute angle to the horizontal plane. The diameter of the gas outlet inclined pipe 16 decreases continuously or in segments from the inlet to the outlet. The reduction in pipe diameter reduces the cross-section of the raw coal gas flow, causing the raw coal gas flow velocity to increase above the critical conveying velocity. This flow velocity carries dust to the cyclone dust collector connected to the outlet of the gas outlet inclined pipe 16, thereby improving the conveying efficiency.

[0044] The gas velocity of the raw coal flowing through the inclined gas outlet pipe 16 increases to above the critical conveying velocity. The high velocity environment causes some of the dust that cannot be carried away to slide back to the kiln head hood 10 along the inclined pipe wall inside the gas outlet pipe 16. The inclined pipe wall provides a return path, and the dust falls back under the action of gravity, reducing the accumulation in the pipe and enhancing the system's self-cleaning ability.

[0045] When adjusting the structural parameters of the rotary pyrolysis kiln body 6, if the dust emission tendency value exceeds the safety threshold, the kiln rotation speed is reduced while the kiln length is increased. The combined effect of reducing the rotation speed and increasing the kiln length causes the movement of pulverized coal within the rotary pyrolysis kiln body 6 to change to a rolling mode, and reduces the material spillage height, thus controlling dust emission at its source.

[0046] After adjusting structural parameters to suppress dust generation, the oil and gas output path is optimized and an inclined tube structure is installed in the rising section of the oil and gas. With dust generation suppressed, the raw coal gas from the gas collection chamber 15 enters the enlarged initial output pipe section. The flow velocity is lower than the gravity settling threshold, allowing medium and large-diameter dust particles to separate by gravity settling within the initial output pipe section. The raw coal gas then enters the inclined gas outlet pipe 16. The reduced diameter of the inclined gas outlet pipe 16 increases the raw coal gas flow velocity above the critical conveying velocity. This velocity carries the remaining fine dust into the cyclone dust collector, achieving multi-stage dust removal.

[0047] The optimized oil and gas output path and the sequential arrangement of inclined pipe structures constitute a dust control sequence. In the first stage, the diameter of the initial output pipe section is increased to control the gas velocity of the raw coal gas flowing from the gas collecting chamber 15 to below the gravity settling threshold velocity. The low velocity environment allows dust particles with high settling rates to separate by gravity settling. In the second stage, the raw coal gas enters the gas outlet inclined pipe 16. The inclination angle and gradually decreasing diameter of the gas outlet inclined pipe 16 increase the raw coal gas velocity above the conveying threshold velocity. The velocity above the conveying threshold velocity relies on hydrodynamics to prevent dust deposition and transport the dust to the dust collector. This sequential design improves the overall dust removal effect.

[0048] In the field of pulverized coal pyrolysis technology, this invention provides a systematic method to address the problem of excessively high oil, gas, and dust content at the outlet of rotary pyrolysis kiln 6. The method begins by collecting particle size distribution data of the pulverized coal raw material. The pulverized coal samples are processed using sieving analysis, and representative samples are graded and sieved using a standard sieve set to obtain the weight distribution of particles of different sizes. Based on the weight distribution, the cumulative mass percentage of particles smaller than a preset threshold is calculated as a characteristic value representing the proportion of small-size pulverized coal. Simultaneously, the initial operating parameters of the rotary pyrolysis kiln 6 are collected, including kiln rotation speed, kiln length, and outlet pipe diameter, providing basic input for subsequent analysis.

[0049] A kinematic model of material movement within the rotary pyrolysis kiln 6 was constructed using particle size distribution data and initial operating parameters as input. The kinematic model is based on the kiln's geometric parameters and kinematic equations, with input parameters including kiln rotation speed and particle size distribution data. The model simulates the trajectory of pulverized coal particles within the rotary pyrolysis kiln 6 at different kiln rotation speeds, considering the effects of centrifugal force and gravity during kiln rotation. The throwing height and throwing frequency of the material are extracted from the simulated trajectory; the throwing height refers to the height the particles are thrown, and the throwing frequency refers to the number of times particles are thrown per unit time. The throwing height and throwing frequency are multiplied, and the result is quantified as a numerical value for dust emission tendency, used to assess the degree of dust emission risk.

[0050] The dust emission tendency value is compared with a preset safety threshold. When the dust emission tendency value exceeds the safety threshold, the structural parameters of the rotary pyrolysis kiln 6 are adjusted. Adjustments include extending the kiln length and setting the kiln rotation speed from a higher range to a lower value. Extending the kiln length increases the residence time of pulverized coal in pyrolysis, while reducing the kiln rotation speed changes the material movement mode from a throwing mode to a rolling mode, reducing the material drop height and thus suppressing dust generation. For example, setting the kiln rotation speed to 1.5 rpm and the kiln length to 55 meters works together to change the movement of pulverized coal within the rotary pyrolysis kiln 6 to a rolling mode.

[0051] After adjusting the structural parameters, the oil and gas output path was optimized. A gas collection chamber 15 was installed on the upper part of the kiln head hood 10, shifting the outlet point of the raw coal gas from the kiln tail to the gas collection chamber 15. An initial output pipe section was set up from the gas collection chamber 15, and the diameter of the initial output pipe section was designed to be larger than the diameter of the coal gas outlet pipe 14 located at the kiln tail in the prior art. The increased pipe diameter caused the raw coal gas flow velocity through the initial output pipe section to be lower than the gravity settling boundary flow velocity. Relying on the reduced flow velocity and gravity, large-diameter dust particles with a density greater than that of oil and gas settled in the initial output pipe section, achieving preliminary separation.

[0052] After optimizing the oil and gas output path, a gas outlet inclined pipe 16 is installed in the rising section of the oil and gas pipeline. The inlet of the gas outlet inclined pipe 16 is connected to the initial output pipe section, and the axis of the gas outlet inclined pipe 16 extends upward at an acute angle to the horizontal plane. The diameter of the gas outlet inclined pipe 16 decreases continuously or in segments from the inlet to the outlet. The reduction in pipe diameter reduces the cross-section of the raw coal gas flow, causing the raw coal gas flow velocity to increase above the critical conveying velocity. This flow velocity carries dust to the cyclone dust collector connected to the outlet of the gas outlet inclined pipe 16, improving conveying efficiency. The increased raw coal gas flow velocity through the gas outlet inclined pipe 16, exceeding the critical conveying velocity, causes some of the dust that cannot be carried away to slide back to the kiln head hood 10 along the inclined pipe wall within the gas outlet inclined pipe 16. The inclined pipe wall provides a return path, reducing pipeline accumulation.

[0053] After dust generation is suppressed, the raw coal gas from the gas collection chamber 15 enters the initially expanded output pipe section. The flow velocity is lower than the gravity settling threshold, causing medium and large-diameter dust particles to separate by gravity settling within the initial output pipe section. The raw coal gas then enters the inclined gas outlet pipe 16. The reduced diameter of the inclined gas outlet pipe 16 increases the raw coal gas flow velocity above the critical conveying velocity. This velocity carries the remaining fine dust into the cyclone dust collector. Optimizing the oil and gas output path and setting the inclined pipe structure sequentially constitutes a dust control sequence. In the first stage, the diameter of the initial output pipe section is expanded, controlling the raw coal gas flow velocity below the gravity settling threshold. This low-velocity environment allows dust particles with higher settling rates to separate by gravity settling. In the second stage, the raw coal gas enters the inclined gas outlet pipe 16. The tilt angle and gradually decreasing pipe diameter increase the raw coal gas flow velocity above the critical conveying velocity. This velocity, exceeding the critical conveying velocity, uses hydrodynamics to prevent dust deposition and convey the dust to the dust collector.

[0054] By combining the above steps, the method forms a multi-stage dust control sequence, adjusts structural parameters to suppress dust sources, optimizes oil and gas pathways to achieve gravity settling, and uses an inclined pipe structure to promote efficient transportation. Ultimately, the dust content of the oil and gas at the outlet is significantly reduced, improving pipeline flowability and tar product quality, and enhancing production economics.

[0055] In the industrial production of pulverized coal pyrolysis, when rotary pyrolysis kiln 6 processes pulverized coal with a particle size distribution of 0-30 mm, the proportion of small-diameter particles is often relatively high. The kiln's rotation speed of 2-3 rpm easily triggers material dust, resulting in an outlet oil and gas dust content of 250-270 g / standard cubic meter, causing pipe blockage and a decline in tar quality. To address this scenario, the following implementation example is used: The weight distribution of the pulverized coal sample is obtained through sieving analysis, and the cumulative mass percentage of particles smaller than 1 mm is calculated as a characteristic value. Simultaneously, the initial operating parameters of rotary pyrolysis kiln 6 are collected, including kiln rotation speed of 2.5 rpm, kiln length of 50 meters, and outlet pipe diameter of 0.5 meters. The particle size distribution data and initial parameters are input into a kinematic model to simulate the movement trajectory of pulverized coal particles within the kiln. The throwing height and frequency are extracted, and the product calculation yields a dust-generating tendency value of 85, exceeding the preset safety threshold of 60. Therefore, the kiln length was extended to 55 meters, and the kiln rotation speed was set to 1.5 rpm, changing the material movement mode from scattering to rolling, thus reducing the drop height. Subsequently, a gas collection chamber 15 was installed above the kiln head hood 10, shifting the raw coal gas outlet from the kiln tail to the gas collection chamber 15, and the initial pipe diameter of the gas collection chamber 15 outlet was enlarged to 0.8 meters, reducing the raw coal gas flow velocity to 1.2 m / s, below the gravity settling threshold velocity of 1.5 m / s, allowing large-diameter dust particles to settle and separate in the initial output pipe section. Then, a gas outlet inclined pipe 16 was installed, its inlet connected to the initial output pipe section, with its axis inclined upwards at a 30-degree angle to the horizontal plane. The pipe diameter was gradually reduced from 0.8 meters to 0.4 meters, increasing the flow velocity to 2.5 m / s, above the critical conveying velocity of 2.0 m / s, carrying fine dust into the cyclone dust collector. After these adjustments, the oil and gas dust content at the outlet was reduced to 50 grams per standard cubic meter, and the frequency of pipe blockage was significantly reduced.

[0056] Another embodiment involves a rotary pyrolysis kiln 6 system with an annual production capacity of 1 million tons of clean coal. The cumulative mass percentage of particles smaller than 0.5 mm in the pulverized coal raw material reaches 40%, and the initial kiln rotation speed is 3 rpm. Based on the collected particle size distribution and kiln parameters, a kinematic model was constructed to calculate the dust emission tendency value as 95, far exceeding the safety threshold. When adjusting the structural parameters, the kiln length was increased to 58 meters, and the rotation speed was reduced to 1.5 rpm to promote the material rolling mode operation. When optimizing the oil and gas output path, a gas collection chamber 15 was set on the upper part of the kiln head hood 10, with the initial pipe diameter increased to 1.0 meter and the flow velocity controlled at 1.0 m / s, utilizing gravity settling to separate medium-sized dust particles. The gas outlet inclined pipe 16 adopts a segmented reduction design, with an inlet pipe diameter of 1.0 meter, an outlet pipe diameter of 0.3 meter, and an inclination angle of 25 degrees, so that the flow velocity jumps to 3.0 m / s, ensuring efficient dust delivery to the dust collector, while some dust-free particles slide back to the kiln head hood 10 along the inclined pipe wall. After implementation, the dust content stabilized below 60 grams per standard cubic meter, the purity of tar products improved, and economic benefits increased.

[0057] For the small rotary pyrolysis kiln application, the particle size distribution of pulverized coal showed that particles smaller than 0.3 mm accounted for 50%. The initial kiln rotation speed was 2 rpm, and the length was 45 meters. The dust emission tendency was calculated to be 80. By extending the kiln to 50 meters and setting the rotation speed to 1.5 rpm, dust generation was suppressed. In the oil and gas path optimization, the outlet pipe diameter of the gas collecting chamber 15 was increased from 0.4 meters to 0.6 meters, and the flow velocity was reduced to 0.8 m / s, achieving gravity settling. The diameter of the gas outlet inclined pipe 16 was continuously reduced to 0.2 meters, the inclination angle was 35 degrees, and the flow velocity was increased to 2.8 m / s, forming a multi-stage dust control sequence. Finally, the oil and gas dust content at the outlet was reduced to 45 g / standard cubic meter, improving production continuity and reducing maintenance costs.

[0058] Under high-temperature pyrolysis conditions, the dust emission tendency value of rotary pyrolysis kiln 6 when processing high-volatile pulverized coal often increases due to fluctuations in raw material characteristics. For example, when the proportion of particles smaller than 1 mm in the pulverized coal is 45%, the dust emission tendency value is 90. By simultaneously adjusting the kiln length to 56 meters and the rotation speed to 1.5 rpm, the scattering height is reduced; the diameter of the gas collecting chamber 15 is increased to 0.9 meters, and the low-velocity flow field promotes dust settling; the inclined design of the gas outlet inclined pipe 16, combined with the reduced pipe diameter, maintains a flow velocity above 2.2 m / s to prevent deposition. This method has strong adaptability and can control the dust content below 120 g / standard cubic meter under different raw material characteristics, supporting long-term stable operation.

Claims

1. A method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln, characterized in that, include: Collect particle size distribution data of pulverized coal raw materials and initial operating parameters of rotary pyrolysis kiln (6), the initial operating parameters including kiln rotation speed, kiln length and gas outlet pipe diameter; Using the particle size distribution data and the initial operating parameters as input, the characteristic of high proportion of small-particle-size pulverized coal is identified, and the dust-raising tendency of the material in the rotary pyrolysis kiln (6) is calculated. Based on the value of the dust tendency, the structural parameters of the rotary pyrolysis kiln (6) are adjusted. The adjustment of the structural parameters includes extending the kiln length and setting the kiln rotation speed from 2-3 rpm to 1.5 rpm to reduce the material drop height. After adjusting the structural parameters, the oil and gas output path is optimized. The optimized oil and gas output path includes changing the raw coal gas outlet location to the gas collection chamber (15) above the kiln head hood (10) and expanding the initial pipe diameter of the outlet of the gas collection chamber (15). After optimizing the oil and gas output path, a gas outlet inclined pipe (16) is set in the oil and gas rising section, and the diameter of the gas outlet inclined pipe (16) gradually decreases along the flow direction. By adjusting the structural parameters, optimizing the oil and gas output path, and setting the gas outlet inclined pipe (16), the dust content of the outlet oil and gas was reduced.

2. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 1, characterized in that, The collection of particle size distribution data for pulverized coal raw materials includes: The weight distribution of particles of different sizes was obtained by processing pulverized coal samples using sieve analysis. Based on the obtained weight distribution, calculate the cumulative mass percentage of particles with a particle size smaller than a preset threshold; The calculated cumulative mass percentage is used as a characteristic value representing the proportion of small-diameter pulverized coal in the particle size distribution data.

3. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 2, characterized in that, The calculation of the dust emission tendency of the material in the rotary pyrolysis kiln (6) includes: Construct a kinematic model of material movement inside the rotary pyrolysis kiln (6). The input parameters of the kinematic model include the kiln rotation speed and particle size distribution data. The kinematic model was constructed to simulate the motion trajectory of pulverized coal particles in the rotary pyrolysis kiln (6) under different kiln rotation speeds. The throwing height and throwing frequency of the material were extracted from the simulated motion trajectory. The extracted scattering height and scattering frequency are multiplied together, and the result is quantified as a value indicating dust tendency.

4. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 3, characterized in that, The adjustment of the structural parameters of the rotary pyrolysis kiln (6) includes: Compare the dust emission tendency value with the preset safety threshold; When the comparison results show that the dust emission tendency value exceeds the safety threshold, the kiln length is extended and the kiln rotation speed is set from 2-3 rpm to 1.5 rpm. Extending the kiln length increases the residence time of pulverized coal pyrolysis; setting the kiln rotation speed to 1.5 rpm changes the material movement mode from a throwing mode to a rolling mode.

5. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 4, characterized in that, The optimized oil and gas output path includes: A gas collection chamber (15) is installed on the upper part of the kiln head cover (10) to transfer the outlet point of the raw coal gas from the kiln tail to the gas collection chamber (15). Set an initial output pipe section leading out from the installed gas collection chamber (15), and design the pipe diameter of the initial output pipe section to be larger than the pipe diameter of the gas outlet pipe (14) located at the kiln tail in the background art; The increased pipe diameter causes the gas velocity of raw coal gas flowing through the initial output pipe section to be lower than the gravitational settling velocity. Due to the reduced flow velocity and gravity, large-diameter dust particles with a density greater than that of oil and gas settle in the initial output pipe section.

6. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 5, characterized in that, The inclined pipe structure installed in the rising section of the oil and gas pipeline includes: A gas outlet inclined pipe (16) is set up. The inlet of the gas outlet inclined pipe (16) is connected to the initial output pipe section. The axis of the gas outlet inclined pipe (16) extends upward at an acute angle to the horizontal plane. The diameter of the gas outlet inclined pipe (16) decreases continuously or in segments from the inlet to the outlet; The reduction in pipe diameter reduces the cross-sectional area of ​​the raw coal gas flowing through the inclined pipe (16) of the coal gas outlet, causing the raw coal gas flow velocity to increase above the critical conveying velocity. This flow velocity carries dust to the cyclone dust collector connected to the outlet of the inclined pipe (16) of the coal gas outlet.

7. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 6, characterized in that, The method further includes: The gas flow velocity of the raw coal gas flowing through the gas outlet inclined pipe (16) increases to above the critical conveying velocity. This high velocity causes some of the dust that cannot be carried away to slide back to the kiln head cover (10) along the inclined pipe wall inside the gas outlet inclined pipe (16).

8. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 7, characterized in that, The adjustment of the structural parameters of the rotary pyrolysis kiln (6) includes: When the dust emission tendency value exceeds the safety threshold, the kiln rotation speed is set to 1.5 revolutions per minute, and the kiln length is set to 55 meters. The kiln rotation speed is set to 1.5 revolutions per minute and the kiln length is set to 55 meters. Together, these factors cause the movement of pulverized coal in the rotary pyrolysis kiln (6) to change to a rolling mode and reduce the material throwing height.

9. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claim 8, characterized in that, After adjusting structural parameters to suppress dust generation, the oil and gas output path was optimized and an inclined pipe structure was installed in the rising section of the oil and gas flow. After dust generation is suppressed, the raw coal gas exported from the gas collection chamber (15) enters the initial output pipe section with an enlarged pipe diameter. The flow velocity is lower than the gravity settling boundary flow velocity, so that medium and large particle size dust particles are separated in the initial output pipe section by gravity settling. The raw coal gas after passing through the initial output pipe section then enters the gas outlet inclined pipe (16). The reduced diameter of the gas outlet inclined pipe (16) increases the gas flow rate of the raw coal gas to above the critical conveying speed. This flow rate carries the remaining fine dust into the cyclone dust collector.

10. The method for reducing the oil and gas dust content at the outlet of a rotary pyrolysis kiln according to claims 5, 6, and 9, characterized in that, Optimize the oil and gas output path and set up the inclined pipe structure to form a dust control sequence: In the first stage, the diameter of the initial output pipe section is increased, and the gas flow velocity of the raw coal gas flowing out of the gas collection chamber (15) is controlled to be lower than the gravity settling threshold flow velocity. The low flow velocity environment allows dust particles with a high settling rate to be separated by gravity settling. In the second stage, raw coal gas enters the gas outlet inclined pipe (16). The inclination angle and gradually decreasing diameter of the gas outlet inclined pipe (16) increase the flow rate of raw coal gas to above the critical conveying speed. The flow rate above the critical conveying speed relies on fluid dynamics to prevent dust deposition and convey the dust to the dust collector.

Images