Three-stage continuous cooling structure of low-rank coal pyrolysis device and semi-coke cooling control method

Abstract

This invention relates to the field of coal pyrolysis technology, and more particularly to a three-stage continuous cooling structure and a semi-coke cooling control method for a low-rank coal pyrolysis device. The three-stage continuous cooling structure includes a transition section, an air-cooling section, and a water-cooling section. Multiple semi-coke feeding pipes are connected to the bottom of each carbonization chamber. The transition section, air-cooling section, and water-cooling section are arranged from top to bottom along the semi-coke feeding pipes. A quenching buffer section is equipped with a quenching buffer tank, and the lower end of the semi-coke feeding pipe is connected to the quenching buffer tank. The air-cooling section includes an air-cooling box located around the semi-coke feeding pipe, and the water-cooling section includes a cooling water tank located around the semi-coke feeding pipe. The coke discharge port at the bottom of the quenching buffer tank is connected to a coke pushing and discharging mechanism. The semi-coke after high-temperature carbonization is gradually cooled to a safe temperature through the three-stage continuous cooling system, achieving gradient cooling of the semi-coke while fully recovering the waste heat of the semi-coke. This also reduces water consumption and prevents the semi-coke from being crushed or oxidized due to rapid cooling, effectively improving the energy efficiency and product quality of the low-rank coal pyrolysis device.

Description

Technical Field

[0001] This invention relates to the field of coal pyrolysis technology, and in particular to a three-stage continuous cooling structure and a semi-coke cooling control method suitable for externally heated low-rank coal dry distillation equipment. Background Technology

[0002] In the coal pyrolysis (dry distillation) process, coal is heated and decomposed to produce products such as semi-coke, raw coal gas, and coal tar. The temperature of the semi-coke produced by pyrolysis is usually as high as 600-800℃, and it needs to be cooled to a safe temperature (60-80℃) in time before it can be transported and stored. Traditional fixed-bed reactors or delayed coking processes usually use wet cooling (water-cooled rapid cooling) or dry cooling to cool the hot coke.

[0003] Wet cooling involves directly immersing the high-temperature semi-coke in water for quenching (such as wet quenching in coke oven production) or cooling it with water spray. This method is fast and the equipment is simple, but it has the following significant disadvantages: First, the heat is lost in the form of steam and cannot be recovered and reused; second, a large amount of cooling water is consumed by evaporation, and the resulting phenolic tar wastewater requires subsequent treatment, increasing costs; third, the temperature shock caused by rapid cooling can easily lead to the semi-coke breaking and pulverizing, affecting the particle size and quality of the product.

[0004] Dry cooling (such as dry quenching technology) uses circulating inert gas to cool hot coke in a closed container. Heat recovery generates steam. This method recovers sensible heat and improves the environment, but it requires large equipment (such as dry quenching furnaces and waste heat boilers) and an inert gas circulation system, resulting in high investment and maintenance costs. Furthermore, dry quenching may pose a fire risk for pyrolysis semi-coke (which is finer and more reactive than coke) and is not suitable for direct application in small-scale low-rank coal pyrolysis plants.

[0005] When producing semi-coke using an externally heated pyrolysis furnace, the semi-coke is typically discharged through multiple feed pipes at the bottom of the furnace. To achieve semi-coke cooling, cooling mechanisms are often installed at the outlet of the feed pipes (e.g., using water-cooled conveying, the semi-coke falls directly into a water-sealed trough through the feed pipe and is cooled to below 60°C), or it undergoes a short-stage air cooling process followed immediately by cooling in a water tank. While these methods can reduce the semi-coke temperature to a safe range, they suffer from discontinuous cooling and insufficient heat recovery. On the one hand, relying solely on water cooling not only wastes a large amount of sensible heat but also consumes a large amount of water, reducing the overall thermal efficiency of the coal pyrolysis system. On the other hand, the temperature reduction from air cooling at the feed pipe outlet is very limited, and water cooling remains the primary solution for cooling. Furthermore, water cooling at higher semi-coke temperatures can lead to rapid shrinkage, pulverization, and sudden tar condensation, which are detrimental to product quality and subsequent tar recovery.

[0006] Application publication number CN111518581A discloses "A vertical multi-pipe segmented air-guided external heating method and apparatus for pulverized coal dry distillation". A cooling section is set below the high-temperature dry distillation section, and the semi-coke is indirectly cooled by circulating water. The semi-coke then enters the quenching box and is discharged from the coke outlet. While the cooling section uses a single water-cooling indirect cooling method, which avoids the consequences of direct water quenching, it still suffers from a short cooling path and insufficient cascade utilization of waste heat. A large amount of sensible heat from the high-temperature semi-coke is transferred to the heat exchange medium—water. This leads to an increase in water temperature requiring stronger cooling circulation, and also results in a significant amount of energy not being recovered and utilized.

[0007] Therefore, current technology lacks a continuous multi-stage cooling design to allow semi-coke to cool down gradually in stages within the feeding pipe: first, final pyrolysis and preliminary cooling are completed in a high-temperature section; then, some sensible heat is extracted through an air-cooling section; and finally, the temperature is reduced to the finished product temperature through a water-cooling section. Such a multi-stage structure is expected to optimize the thermal gradient during semi-coke cooling, alleviate thermal stress, and fully utilize waste heat. If the waste heat from air cooling can be recycled for drying the coal entering the furnace, system efficiency will be further improved. Simultaneously, multi-stage cooling requires coordinating the cooling media and flow rates of each stage to achieve a robust thermal control path, ensuring that the semi-coke is adequately cooled without causing overcooling or uneven cooling. Summary of the Invention

[0008] This invention provides a three-stage continuous cooling structure for a low-rank coal pyrolysis device and a semi-coke cooling control method. The semi-coke after high-temperature dry distillation is continuously cooled in the feeding pipeline through a three-stage continuous cooling process: a transition section, an air-cooling section, and a water-cooling section, gradually cooling down to a safe temperature. The semi-coke cooling control system can achieve gradient cooling of the semi-coke while fully recovering the waste heat of the semi-coke, and can also reduce water consumption, avoid the semi-coke from being crushed or oxidized due to rapid cooling, and effectively improve the energy efficiency and product quality of the low-rank coal pyrolysis device.

[0009] To achieve the above objectives, the present invention employs the following technical solution: A three-stage continuous cooling structure for a low-rank coal pyrolysis device is disclosed. The low-rank coal pyrolysis device includes a high-temperature dry distillation section with multiple spaced combustion chambers and dry distillation chambers. A coke pushing and discharging mechanism is located below the low-rank coal pyrolysis device. The three-stage continuous cooling structure includes a transition section, an air-cooled section, and a water-cooled section. The bottom of each dry distillation chamber is connected to multiple semi-coke feeding pipes. The transition section, air-cooled section, and water-cooled section are arranged from top to bottom along the semi-coke feeding pipes. A coke quenching buffer section is provided with a coke quenching buffer tank, and the lower end of the semi-coke feeding pipe is connected to the coke quenching buffer tank. The air-cooled section includes an air-cooling box located around the semi-coke feeding pipe, and the water-cooled section includes a cooling water tank located around the semi-coke feeding pipe. The coke discharge port at the bottom of the coke quenching buffer tank is connected to the coke pushing and discharging mechanism.

[0010] Multiple rows of semi-coke feeding pipes are arranged in parallel to form a semi-coke feeding pipe bundle. The semi-coke feeding pipes are made of heat-resistant alloy steel.

[0011] The transition section is connected to the air-cooled section at the semi-coke feeding pipe with a raw coal gas outlet; the air-cooled box has an air-cooled inlet at the bottom and an air-cooled outlet at the top, and multiple baffles are arranged along the height inside the air-cooled box; the air-cooled inlet is connected to the atmosphere, and the air-cooled outlet is connected to the air inlet of the blower.

[0012] The cooling water tank has a water-cooled inlet at the lower end of one end and a water-cooled outlet at the upper part of the other end; the water-cooled inlet and the water-cooled outlet are connected by a cooling water circulation pipe outside the cooling water tank, and a circulation pump 7 is installed on the cooling water circulation pipe.

[0013] The outer wall of the semi-coke feed pipe located in the cooling section is provided with annular ribs.

[0014] The coke quenching buffer tank is a closed tank. A coke pushing and discharging mechanism is provided at the coke discharge port at the bottom of the coke quenching buffer tank. The coke pushing and discharging mechanism is a sealed discharge valve or a coke pushing device.

[0015] A three-stage continuous cooling structure for a low-rank coal pyrolysis unit further includes a semi-coke cooling control system. The semi-coke cooling control system comprises a first temperature sensor, a second temperature sensor, a third temperature sensor, a cooling airflow regulating device, a cooling waterflow regulating device, and a controller. The first temperature sensor is located at the bottom of the semi-coke feed pipe in the transition section, the second temperature sensor is located at the bottom of the semi-coke feed pipe in the air-cooled section, and the third temperature sensor is located at the bottom of the semi-coke feed pipe in the water-cooled section. The cooling airflow regulating device is located on the cooling air duct downstream of the air-cooled outlet, and the cooling waterflow regulating device is located on the cooling water circulation duct upstream of the water-cooled inlet. The first temperature sensor, the second temperature sensor, the third temperature sensor, the cooling airflow regulating device, and the cooling waterflow regulating device are all connected to the controller. The controller is also connected to a coke pushing and discharging device.

[0016] The cooling airflow regulating device is a frequency converter-controlled fan and / or a cooling airflow regulating valve; the cooling water flow regulating device is a frequency converter-controlled circulating pump 7 and / or a cooling water flow regulating valve.

[0017] A semi-coke cooling control method includes the following process: 1) In the low-rank coal pyrolysis unit, the semi-coke generated after the coal is pyrolyzed in the high-temperature dry distillation section enters each semi-coke feed pipe in the transition section and moves slowly downward. After flowing through the transition section, the temperature of the semi-coke drops from above 700℃ to 500-600℃. Before the semi-coke enters the air-cooling section, the residual volatile matter in the semi-coke is discharged through the raw coal gas outlet. 2) After initial cooling, the semi-coke enters the air-cooling section and continues to move down along the semi-coke feeding pipe. Air is introduced into the air-cooling box by a fan as cooling air. The cooling air flows upward along the multi-layer baffle plate. During this process, it indirectly exchanges heat with the semi-coke in the semi-coke feeding pipe. After passing through the air-cooling section, the temperature of the semi-coke drops to below 300℃. 3) After being cooled by air, the semi-coke enters the water cooling section and continues to move down along the semi-coke feeding pipe. The circulating cooling water is introduced into the cooling water tank by the circulating pump 7. The cooling water and the semi-coke in the semi-coke feeding pipe exchange heat indirectly. After passing through the water cooling section, the temperature of the semi-coke drops to below 80℃. 4) The semi-coke after water cooling enters the coke quenching buffer section and is discharged quantitatively through the coke pushing and discharging device at the bottom of the coke quenching buffer tank.

[0018] A semi-coke cooling control system is used to control the continuous and stable cooling of the semi-coke, which specifically includes the following process: 1) The half-coke temperature at the end of the transition section is detected in real time using the first temperature sensor, the half-coke temperature at the end of the air-cooled section is detected in real time using the second temperature sensor, and the half-coke temperature at the end of the water-cooled section is detected in real time using the third temperature sensor. 2) Cooling airflow adjustment: The controller compares the detection value of the second temperature sensor with the preset value of the semi-coke temperature. By adjusting the power of the variable frequency fan or adjusting the opening of the cooling airflow control valve, the airflow into the air-cooled box is adjusted until the detection value of the second temperature sensor is within the range of the preset value of the semi-coke temperature. 3) Cooling water volume adjustment: The controller compares the detection value of the third temperature sensor with the second preset value of half coke temperature, and adjusts the flow rate of cooling water entering the cooling water tank by adjusting the frequency of the circulating pump 7 or adjusting the opening of the cooling water flow control valve until the detection value of the third temperature sensor is within the range of the second preset value of half coke temperature. 4) Feeding rate adjustment: Based on the real-time detection values ​​of the first and second temperature sensors, determine the combined trend of the semi-coke temperature at the end of the transition section and the end of the air-cooling section, and adjust the feeding rate of the semi-coke or the opening and closing cycle of the coke discharge port using the coke pushing and discharging device; by adjusting the residence time of the semi-coke in the transition section and the air-cooling section, ensure that the semi-coke temperature when entering the water-cooling section meets the requirements. 5) Temperature Coordinated Regulation: The detection values ​​of the first, second, and third temperature sensors are compared with the preset gradient target temperature in the controller. The controller interlocks and controls the cooling airflow regulation device, cooling waterflow regulation device, and coke pushing and discharging device to coordinately adjust the cooling airflow, cooling waterflow, and feeding rate. This makes the semi-coke temperature at the end of the transition section, the end of the air-cooled section, and the end of the water-cooled section gradually approach the gradient target temperature, forming a smooth semi-coke cooling path and stabilizing the semi-coke discharge temperature within the set range.

[0019] Compared with the prior art, the beneficial effects of the present invention are: (1) Achieving cascaded cooling of semi-coke and efficient recovery of waste heat: Most of the sensible heat of the semi-coke is carried away by air in the air-cooling section, thereby realizing the recovery and utilization of heat energy (such as for drying coal entering the furnace); compared with the direct water cooling method, this invention recovers a hot air with a temperature of over 100°C, improving the overall energy efficiency. At the same time, the water-cooling section processes the semi-coke that has been cooled by air cooling, reducing the temperature rise of the circulating cooling water and reducing the energy consumption of the cooling water. In the three-stage cooling, the cooling media of air cooling and water cooling both operate in their most efficient temperature range, and the heat can be utilized step by step, avoiding energy waste.

[0020] (2) Reducing thermal stress and ensuring semi-coke quality: After adopting a three-stage cooling system, the semi-coke achieves gradual cooling with a gentle cooling gradient. The semi-coke is first cooled in an inert atmosphere, then slowly cooled in an air-cooling stage, and finally rapidly cooled and shaped in a water-cooling stage. Compared with the traditional water-cooling method, which is prone to excessive internal temperature difference and cracking / pulverization due to sudden cooling, this method helps maintain the integrity of the semi-coke particles and reduces dust generation. At the same time, tar and other condensates will not suddenly condense and adhere to the surface of the semi-coke at excessively high temperatures. Instead, some of them are carried away by the air during the air-cooling process, and the remaining part will not condense during water cooling due to the lower temperature, thus avoiding the risk of blockage. Ultimately, the strength of the semi-coke product and the tar recovery rate are both improved.

[0021] (3) Reduced environmental pollution and lower operating load: With the three-stage cooling system, the semi-coke is cooled first through the air-cooling section, significantly reducing the evaporation of cooling water in the water-cooling section, resulting in almost no white smoke emissions and wastewater generation, thus providing significant environmental benefits. The circulating cooling water system operates at a lower temperature difference, reducing the risk of scaling and corrosion in the heat exchanger. Furthermore, the cooling medium in the air-cooling section of this invention is air, eliminating the need for expensive inert gases, making the system simple and easy to implement. Compared to dry quenching systems, it eliminates the need for large airtight containers and boiler systems, reducing investment and maintenance costs.

[0022] (4) Stable cooling effect and strong dynamic controllability: This invention achieves precise control of the semi-coke cooling process through multi-point temperature detection and adjustment of air volume and water flow. The ratio of air cooling to water cooling can be flexibly adjusted according to changes in working conditions to ensure that the discharge temperature remains constant at a safe value. Even if the properties of the coal or the working conditions fluctuate, the semi-coke cooling control system can automatically adjust to maintain a stable cooling effect. Operators can monitor the temperature gradient of the semi-coke at each stage of cooling at any time, making adjustments more scientific and based on evidence, thus improving operational reliability. Attached Figure Description

[0023] Figure 1 This is a front view of the three-stage continuous cooling structure of a low-rank coal pyrolysis device according to the present invention.

[0024] Figure 2This is a perspective view of the three-stage continuous cooling structure of a low-rank coal pyrolysis device according to the present invention.

[0025] Figure 3 This is a schematic diagram of the semi-coke cooling control system described in this invention.

[0026] Figure 4 This is the continuous cooling curve of the semi-coke in this embodiment.

[0027] In the diagram: 1-Transition section; 11-Semi-coke feeding pipe; 2-Air-cooled section; 21-Air-cooled box; 22-Air-cooled air inlet; 23-Air-cooled air outlet; 24-Baffle plate; 25-Raw coal gas outlet; 3-Water-cooled section; 31-Cooling water tank; 32-Water-cooled water inlet; 33-Water-cooled water outlet; 4-Coke quenching buffer section; 5-Coke pushing and discharging mechanism; 6-Blower; 7-Circulating pump; 8-Combustion chamber; 9-Drying chamber; 10-Controller; 101-First temperature sensor; 102-Second temperature sensor; 103-Third temperature sensor; 104-Cooling airflow regulating valve; 105-Cooling waterflow regulating valve. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1 , Figure 2 As shown, the present invention discloses a three-stage continuous cooling structure for a low-rank coal pyrolysis device. The low-rank coal pyrolysis device includes a high-temperature dry distillation section, which has multiple spaced combustion chambers 8 and dry distillation chambers 9. A coke pushing and discharging mechanism is provided below the low-rank coal pyrolysis device. The three-stage continuous cooling structure includes a transition section 1, an air-cooled section 2, and a water-cooled section 3. The bottom of each dry distillation chamber 9 is connected to multiple semi-coke feeding pipes 11. The transition section 1, air-cooled section 2, and water-cooled section 3 are arranged from top to bottom along the semi-coke feeding pipes 11. A coke quenching buffer section 4 is provided with a coke quenching buffer tank, and the lower end of the semi-coke feeding pipe 11 is connected to the coke quenching buffer tank. The air-cooled section 2 includes an air-cooled box 21 located around the semi-coke feeding pipe 11, and the water-cooled section 3 includes a cooling water tank 31 located around the semi-coke feeding pipe 11. The coke discharge port at the bottom of the coke quenching buffer tank is connected to the coke pushing and discharging mechanism 5.

[0029] Multiple rows of semi-coke feeding pipes 11 are arranged in parallel to form a semi-coke feeding pipe bundle. The semi-coke feeding pipes 11 are made of heat-resistant alloy steel.

[0030] The semi-coke feeding pipe 11 connecting the transition section 1 and the air-cooled section 2 is provided with a raw coal gas outlet 25; the air-cooled box 21 is provided with an air-cooled inlet 22 at the bottom and an air-cooled outlet 23 at the top, and a multi-layer baffle 24 is provided along the height inside the air-cooled box 21; the air-cooled inlet 22 is connected to the atmosphere, and the air-cooled outlet 23 is connected to the air inlet of the blower 6.

[0031] The cooling water tank 31 has a water-cooled inlet 32 ​​at the lower end of one end and a water-cooled outlet 33 at the upper part of the other end. The water-cooled inlet 32 ​​and the water-cooled outlet 33 are connected through a cooling water circulation pipe outside the cooling water tank 31, and a circulation pump 7 is installed on the cooling water circulation pipe.

[0032] The outer wall of the semi-coke feed pipe 11 located in the cooling section is provided with annular ribs.

[0033] The coke quenching buffer tank is a closed tank. A coke pushing and discharging mechanism 5 is provided at the coke discharge port at the bottom of the coke quenching buffer tank. The coke pushing and discharging mechanism 5 is a sealed unloading valve or a coke pushing device.

[0034] The three-stage continuous cooling structure of the low-rank coal pyrolysis device described in this invention also includes a semi-coke cooling control system; as... Figure 3 As shown, the semi-coke cooling control system consists of a first temperature sensor 101, a second temperature sensor 102, a third temperature sensor 103, a cooling airflow regulating device, a cooling waterflow regulating device, and a controller 10. The first temperature sensor 101 is located at the bottom of the semi-coke feeding pipe 11 in the transition section 1, the second temperature sensor 102 is located at the bottom of the semi-coke feeding pipe 11 in the air-cooled section 2, and the third temperature sensor 103 is located at the bottom of the semi-coke feeding pipe 11 in the water-cooled section 3. The cooling airflow regulating device is located on the cooling air duct downstream of the air-cooled outlet 23, and the cooling waterflow regulating device is located on the cooling water circulation duct upstream of the water-cooled inlet 32. The first temperature sensor 101, the second temperature sensor 102, the third temperature sensor 103, the cooling airflow regulating device, and the cooling waterflow regulating device are respectively connected to the controller 10. The controller 10 is also connected to the coke pushing and discharging device.

[0035] The cooling airflow regulating device is a frequency converter-controlled fan 6 and / or a cooling airflow regulating valve 104; the cooling water flow regulating device is a frequency converter-controlled circulating pump 7 and / or a cooling water flow regulating valve 105.

[0036] The semi-coke cooling control method of the present invention includes the following process: 1) In the low-rank coal pyrolysis unit, the semi-coke generated after the coal is pyrolyzed in the high-temperature dry distillation section enters each semi-coke feed pipe 11 in the transition section 1 and slowly moves downward. After flowing through the transition section 1, the temperature of the semi-coke drops from above 700℃ to 500-600℃. Before the semi-coke enters the air-cooling section 2, the residual volatile matter in the semi-coke is discharged through the raw coal gas outlet 25. 2) After initial cooling, the semi-coke enters the air-cooling section 2 and continues to move down along the semi-coke feeding pipe 11. Air is introduced into the air-cooling box 21 by the fan 6 as cooling air. The cooling air flows upward along the multi-layer baffle 24. During this process, it indirectly exchanges heat with the semi-coke in the semi-coke feeding pipe 11. After passing through the air-cooling section 2, the temperature of the semi-coke drops to below 300℃. 3) After being cooled by air, the semi-coke enters the water cooling section 3 and continues to move down along the semi-coke feeding pipe 11. The circulating cooling water is introduced into the cooling water tank 31 by the circulating pump 7. The cooling water and the semi-coke in the semi-coke feeding pipe 11 exchange heat indirectly. After passing through the water cooling section 3, the temperature of the semi-coke drops to below 80℃. 4) The semi-coke after water cooling enters the coke quenching buffer section 4 and is discharged quantitatively through the coke pushing and discharging device at the bottom of the coke quenching buffer tank.

[0037] A semi-coke cooling control system is used to control the continuous and stable cooling of the semi-coke, which specifically includes the following process: 1) The half-coke temperature at the end of the transition section 1 is detected in real time using the first temperature sensor 101, the half-coke temperature at the end of the air-cooled section 2 is detected in real time using the second temperature sensor 102, and the half-coke temperature at the end of the water-cooled section 3 is detected in real time using the third temperature sensor 103. 2) Cooling airflow adjustment: The controller 10 compares the detection value of the second temperature sensor 102 with the preset value of the semi-coke temperature. By adjusting the power of the fan 6 or adjusting the opening of the cooling airflow control valve, the airflow entering the air-cooled box 21 is adjusted until the detection value of the second temperature sensor 102 is within the range of the preset value of the semi-coke temperature. 3) Cooling water volume adjustment: The controller 10 compares the detection value of the third temperature sensor 103 with the second preset value of half coke temperature, and adjusts the cooling water flow rate into the cooling water tank 31 by adjusting the power of the variable frequency circulating pump 7 or adjusting the opening of the cooling water flow control valve until the detection value of the third temperature sensor 103 is within the range of the second preset value of half coke temperature. 4) Feeding rate adjustment: Based on the real-time detection values ​​of the first temperature sensor 101 and the second temperature sensor 102, determine the combined trend of the semi-coke temperature at the end of the transition section 1 and the air-cooling section 2, and adjust the feeding rate of the semi-coke or the opening and closing cycle of the coke discharge port using the coke pushing and discharging device; by adjusting the residence time of the semi-coke in the transition section 1 and the air-cooling section 2, ensure that the semi-coke temperature when entering the water-cooling section 3 meets the requirements. 5) Temperature Coordinated Regulation: The detected values ​​of the first temperature sensor 101, the second temperature sensor 102, and the third temperature sensor 103 are compared with the preset gradient target temperature in the controller 10. The controller 10 interlocks and controls the cooling airflow regulation device, the cooling waterflow regulation device, and the coke pushing and discharging device to coordinately adjust the cooling airflow, cooling waterflow, and feeding rate. This ensures that the semi-coke temperature at the end of transition section 1, the end of air-cooled section 2, and the end of water-cooled section 3 gradually approaches the gradient target temperature, forming a smooth semi-coke cooling path (e.g., ...). Figure 4 As shown in the figure, the semi-coke discharge temperature is stabilized within the set range.

[0038] This invention discloses a three-stage continuous cooling structure for a low-rank coal pyrolysis device. The low-rank coal pyrolysis device is primarily an externally heated pyrolysis furnace, employing a three-stage continuous cooling structure of transition section 1 + air-cooled section 2 + water-cooled section 3, suitable for continuous cooling of semi-coke after pyrolysis. Transition section 1, air-cooled section 2, and water-cooled section 3 are sequentially arranged along the semi-coke feeding passage below the high-temperature dry distillation section. Transition section 1 is located below the high-temperature dry distillation section, where the semi-coke undergoes the final pyrolysis reaction and initial cooling. Air-cooled section 2 is located below transition section 1, where cooling gas is introduced into the air-cooling box 21 to indirectly exchange heat with the semi-coke in the semi-coke feeding pipe 11, further reducing the semi-coke temperature. Water-cooled section 3 is located below air-cooled section 2, with the lower section of the semi-coke feeding pipe 11 immersed in circulating cooling water in the cooling water tank 31, cooling the semi-coke to the target temperature through indirect heat exchange. The specific structure and working principle are as follows: Transition Section 1: Multiple semi-coke feed pipes 11 are connected to the dry distillation chamber 9 of the upper high-temperature dry distillation section. When the semi-coke enters Transition Section 1, it remains in a high-temperature inert atmosphere, continuing the final pyrolysis reaction and exothermic process during its residence and downward movement. The semi-coke feed channels are preferably made of heat-resistant alloy steel. Since the flue gas inside the combustion chamber 8 does not move downwards, only some residual heat is transferred to Transition Section 1 through the dry distillation chamber wall. Therefore, the temperature of the semi-coke gradually decreases from above 700℃ to 500-600℃ after passing through Transition Section 1. The function of Transition Section 1 is to complete the final pyrolysis of the semi-coke and prepare for subsequent cooling.

[0039] Before the semi-coke enters the air-cooling section 2, the raw coal gas generated in the semi-coke feed pipe 11 needs to be discharged. The raw coal gas outlet 25 is preferably located at the junction of the transition section 1 and the air-cooling section 2 to discharge volatile gases in a timely manner and prevent them from condensing and causing blockage in the cooling section. The raw coal gas outlet 25 is connected to the raw coal gas collection device through the coal gas discharge pipe.

[0040] Air-cooling section 2: Immediately following transition section 1, an air-cooling box 21 is provided around the semi-coke feeding pipe 11 in air-cooling section 2. The air-cooling box 21 contains several layers of baffles 24 to form an upward flow channel for the cooling air. The semi-coke moves downward within the semi-coke feeding pipe 11, and cooling air is introduced into the air-cooling box 21 to carry away the heat from the semi-coke, further cooling it. The length and cooling air volume of air-cooling section 2 are designed according to needs (e.g., to reduce the semi-coke temperature to 300°C at the end of air-cooling section 2). The main sensible heat of the semi-coke is extracted in air-cooling section 2. Air-cooling box 21 preferably has a partitioned heat exchange structure (the semi-coke does not directly contact the air). The semi-coke feeding pipe 11 is a closed feeding channel, and air flows in a jacket outside the semi-coke feeding pipe 11. The cooling air can be ambient air or an inert gas, selected according to safety requirements. This invention preferably uses ambient air and recovers the waste heat of the heated air (e.g., sending it to the furnace top as a heat source for coal drying). The cooling rate of the air-cooled section 2 can be controlled by adjusting the air intake, ensuring that the temperature of the semi-coke drops steadily and preventing cracking due to sudden cooling.

[0041] The air-cooled box 21 is equipped with an air-cooled inlet 22 and an air-cooled outlet 23. The air-cooled inlet 22 is connected to the atmosphere via a fan 6 to introduce air, and the air-cooled outlet 23 is connected to an air duct to output heated air. The semi-coke feeding pipes 11 inside the air-cooled box 21 are arranged in a bundle. The air-cooled inlet 22 is preferably located at the lower part of the air-cooled box 21, and the corresponding air-cooled outlet 23 is located at the upper part of the air-cooled box 21. The cooling air flows from bottom to top through the semi-coke feeding pipe bundle in a meandering manner, achieving efficient reverse heat exchange.

[0042] Water-cooled section 3: After passing through the air-cooled section 2, the semi-coke feed pipe 11 continues downward through the cooling water tank 31, where the semi-coke is finally cooled by cooling water. The cooling water tank 31 adopts a closed structure, and the semi-coke indirectly exchanges heat with the cooling water inside the semi-coke feed pipe 11, transferring the remaining heat to the cooling water, further reducing the temperature of the semi-coke to a safe discharge temperature (usually below 80℃). The length of the water-cooled section 3 is determined according to the discharge temperature of the semi-coke (e.g., when the cooling water height in the cooling water tank 31 is 4.4m, the temperature can be reduced to 80℃). The water-cooled section 3 preferably uses circulating cooling water for cooling, achieving reuse and reducing water consumption. The cooling water tank 31 is equipped with a water-cooled inlet 32 ​​and a water-cooled outlet 33, which are connected by a cooling water circulation pipe and form a cooling water circulation system under the action of the circulation pump 7. A heat exchanger is installed on the cooling water circulation pipe to cool the circulating cooling water, so as to maintain the water temperature in the cooling water tank 31 within a set range. Compared to air cooling, water cooling has a stronger cooling capacity. Setting up a water cooling section 3 at the end of the semi-coke discharge can ensure that the semi-coke discharge temperature is below the ignition point, which is convenient for transportation.

[0043] Quenching Buffer Section 4: The water-cooling section 3 connects to the quenching buffer section 4. The quenching buffer section 4 adopts a closed structure quenching buffer tank to prevent the semi-coke from being directly exposed to air and reigniting, and also plays a role in stabilizing pressure and locking gas. The quenching buffer tank is connected to the coke outlet of all semi-coke discharge pipes 11 to receive the semi-coke discharged from the water-cooling section 3. The bottom of the quenching buffer tank is equipped with a coke discharge port and a coke pushing and discharging device (such as a sealed discharge valve or a coke pushing device) for quantitatively discharging the cooled semi-coke.

[0044] After passing through a three-stage continuous cooling structure, the high-temperature semi-coke achieves continuous cooling. Transition section 1 ensures complete reaction, air-cooling section 2 pre-cools and extracts most of the heat, and water-cooling section 3 cools the semi-coke to the target temperature. This three-stage cooling structure achieves full tiered utilization—distributing the high-temperature sensible heat of the semi-coke to different media. Air-cooling section 2 absorbs the recyclable portion, while water-cooling section 3 only handles the final cooling, significantly reducing load and water consumption. More importantly, it achieves a gradual decrease in semi-coke temperature, avoiding sudden cooling shocks and reducing pulverization and thermal stress. Since transition section 1, air-cooling section 2, and water-cooling section 3 are all located along the semi-coke feeding path, they do not affect the continuous movement of the semi-coke, resulting in a simple and reliable structure.

[0045] By adopting a three-stage continuous cooling structure, the semi-coke achieves gradient cooling, that is, gradually reducing to the preset target temperature. The gradient cooling target of the semi-coke can be set as: the end temperature T of transition section 1. A0 The temperature ranges from 400 to 600℃, and the end temperature T of the air-cooled section 2 is... B0 The water-cooled section has a terminal temperature of 250–300℃ and a final temperature T at the end of section 3. C0 The temperature is below 80℃. During the semi-coke cooling control process, the heat exchange intensity between the air-cooled section 2 and the water-cooled section 3 is adjusted first, even if the detection value of the second temperature sensor 102 reaches T. B0 This allows the detection value of the third temperature sensor 103 to reach T. C0 Then, the feeding rate is adjusted to ensure that the detection value of the first temperature sensor 101 reaches T. A0 This allows for three-stage, step-by-step control of the semi-coke temperature.

[0046] The process and principle of the semi-coke cooling control method described in this invention are as follows: 1. Airflow Adjustment During Air Cooling: A variable frequency fan 6 and / or a cooling airflow regulating valve 104 are installed on the cooling air duct downstream of the air-cooling outlet 23 to adjust the air velocity and flow rate entering the air-cooling box 21. By changing the airflow, the cooling intensity of the semi-coke in the air-cooling section 2 can be controlled. For example, when the semi-coke temperature is too high, the airflow is increased to enhance cooling; when it is necessary to maintain the semi-coke temperature (such as to avoid it falling below the tar dew point), the airflow can be reduced. In addition, the cooling air temperature at the air-cooling outlet 23 can be monitored and the airflow can be interlocked to keep the cooling air outlet temperature within the target range, thereby ensuring that the heat of the semi-coke is fully extracted and the semi-coke temperature drops to the expected range. When the cooling air temperature at the air-cooling outlet 23 is measured to be too high, it indicates that the heat exchange in the air-cooling section 2 is close to saturation, at which point the airflow needs to be increased or the feed rate reduced.

[0047] 2. Water Temperature and Flow Rate Regulation During Water Cooling: In water-cooling section 3, the cooling rate of water-cooling section 3 can be controlled by adjusting the circulating cooling water flow rate or the inlet water temperature of cooling water tank 31. The control target can be set to maintain the semi-coke temperature at the outlet of water-cooling section 3 within a safe range (e.g., below 80℃). If the semi-coke temperature at the outlet of water-cooling section 3 is too high, the inlet water temperature of cooling water tank 31 can be reduced or the cooling water flow rate can be increased; if the semi-coke temperature at the outlet of water-cooling section 3 is far below the requirement (wasting cooling capacity), the cooling water flow rate can be reduced or the inlet water temperature of cooling water tank 31 can be appropriately increased to achieve energy saving. Similarly, the water temperature at the water-cooling outlet of the water-cooling tank can also be monitored to avoid a decrease in cooling effect due to excessively high water temperature.

[0048] 3. Multi-point temperature monitoring and gradient control: Temperature sensors are installed in each cooling section, such as a thermocouple at the end of transition section 1, the end of air-cooled section 2, and the end of water-cooled section 3, to detect the temperature of the semi-coke at the corresponding measurement point. Controller 10 (preferably a PLC controller) establishes a temperature gradient distribution curve based on this. The temperature control path must ensure that: the temperature at the end of transition section 1 is >400℃ (to ensure most of the volatiles are released), the temperature at the end of air-cooled section 2 is within the range of 250-300℃ (to avoid a large amount of light components condensing during water cooling), and the temperature at the end of water-cooled section 3 is <80℃ (to ensure safety). When the temperature of a certain section deviates from the set target range, controller 10 can adjust the parameters of the cooling medium in adjacent sections. For example, if the temperature of the semi-coke at the end of air-cooled section 2 is too high, it indicates insufficient air cooling, and the speed of fan 6 is automatically increased or the opening of cooling airflow regulating valve 104 is increased; conversely, if the temperature of the semi-coke at the end of air-cooled section 2 is too low, it indicates over-cooling, and the speed of fan 6 is automatically decreased or the opening of cooling airflow regulating valve 104 is decreased.

[0049] 4. Semi-coke discharge rhythm control: By adjusting the opening and closing frequency of the sealed discharge valve at the bottom of the quenching buffer tank or the pushing speed of the coke pusher, the residence time of semi-coke in the semi-coke feeding pipe 11 can be controlled. It is generally desirable that the total residence time of semi-coke in the three cooling sections is sufficient to achieve the required cooling. The semi-coke discharge rhythm can be controlled in a closed loop with the semi-coke temperature monitoring to ultimately ensure stable semi-coke cooling effect.

[0050] When the low-rank coal pyrolysis unit experiences an emergency shutdown or cooling system failure, emergency cooling measures must be activated, including temporarily spraying water or injecting inert gas into the air-cooled section 2 and the semi-coke feed pipe 11 to rapidly reduce the temperature of the semi-coke and prevent it from overheating and burning. This emergency measure is only activated under abnormal circumstances. During normal operation, the three-stage continuous cooling structure and semi-coke cooling control method described in this invention can ensure the safe cooling of the semi-coke.

[0051] As an alternative, nitrogen or low-oxygen waste gas can be used instead of air as cooling air, but gas circulation equipment needs to be added. This invention preferably uses air as cooling air. In the air-cooled box 21, the cooling air does not directly contact the semi-coke, and the semi-coke has already been released and volatilized under an inert atmosphere, making it less prone to oxidation. Therefore, using air as cooling air is safe and reliable.

[0052] The semi-coke feeding pipe 11 can adopt different structural forms in the air-cooled section 2 and the water-cooled section 3. For example, in the air-cooled section 2, a corrugated pipe or a structure with built-in turbulence elements can be used to improve the heat transfer coefficient. In the water-cooled section 3, a spiral guide vane can be installed to guide the semi-coke to spiral down, increasing the residence and heat transfer time. The outer wall can be welded with annular fins or directly use finned tubes.

[0053] The length of the water-cooling section 3 can be adjusted according to requirements. For example, if a lower temperature of the finished semi-coke is desired (less than 60°C), the length of the water-cooling section 3 can be appropriately increased or the inlet water temperature of the cooling water tank 31 can be reduced.

[0054] A small amount of protective gas can be introduced into the quenching buffer tank to prevent the semi-coke from oxidizing due to residual heat.

[0055] As illustrated by the above embodiments, this invention achieves the goal of continuous three-stage cooling of semi-coke, ensuring thorough high-temperature dry distillation, efficient air-cooling pre-cooling, and reliable and complete water cooling. Compared with traditional solutions, the waste heat of the semi-coke is recovered and utilized in stages, improving both product quality and system energy efficiency. This invention has a simple and reliable structure and can be easily applied to the discharge cooling retrofit of various externally heated or internally heated pyrolysis furnaces, demonstrating high practical value.

[0056] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0057] Example: In this embodiment, the low-rank coal pyrolysis unit is an externally heated pyrolysis furnace for low-rank pulverized coal, with a processing capacity of 1 ton / hour. The designed temperature of the produced semi-coke is <80℃ to facilitate belt conveying. At the junction of the high-temperature dry distillation section and the transition section 1, each dry distillation chamber 9 is connected to 6 parallel semi-coke feed pipes 11. The semi-coke feed pipes 11 are made of heat-resistant alloy steel (capable of withstanding temperatures up to 1100℃), and there are a total of 36 pipes in 6 rows and 6 columns, forming a semi-coke feed pipe bundle. The three-stage continuous cooling structure is as follows: 1. Transition Section 1 Configuration: The internal cross-sectional dimensions of the dry distillation chamber 9 are 2000mm × 200mm, and the height of the semi-coke feed pipe 11 in transition section 1 is 0.5 meters. The upper end of the semi-coke feed pipe 11 in transition section 1 is connected to the dry distillation chamber 9, and the lower end is connected to the semi-coke feed pipe 11 in the air-cooling section 2. Since transition section 1 is a high-temperature section, the wall thickness of the corresponding semi-coke feed pipe is increased to withstand high-temperature corrosion. The main function of transition section 1 is to allow the semi-coke to complete the residual volatilization and precipitation. For this purpose, a raw coal gas outlet 25 with a diameter of 50mm is opened on one side at the connection between each semi-coke feed pipe 11 and the air-cooling section 2, and a horizontal raw coal gas outlet pipe is connected to collect the remaining volatiles. In this embodiment, a buffer chamber is set at the raw coal gas outlet 25. After all the raw coal gas outlet pipes are collected into the raw coal gas main pipe, they are then connected to the raw coal gas collection system and the exhaust fan. Before the semi-coke enters the air-cooling section 2, ensure that the gaseous products (mainly the remaining raw coal gas and light tar vapor) in the semi-coke feed pipe 11 are discharged in time to prevent them from condensing and clogging the pipe in the downstream air-cooling section 2. The discharged raw coal gas enters the subsequent purification process after dust removal and condensation treatment.

[0058] 2. Configuration of Air-Cooled Section 2: The middle section (1.5 meters high) of the semi-coke feeding pipe 11 passes through the air-cooled box 21, and the entire semi-coke feeding pipe bundle runs through a rectangular cross-section air-cooled box 21. The dimensions of the air-cooled box 21 are 2m long × 6m wide × 4m high. The main body of the air-cooled box 21 is made of Q235 steel and lined with rock wool for thermal insulation. A rectangular air-cooled outlet 23 with a hydraulic diameter of 300mm is opened on one side of the upper part of the air-cooled box 21, and five air-cooled inlets 22 are evenly opened horizontally on one side of the lower part. The air-cooled outlet 23 is connected to an 11kW fan 6 (in this embodiment, a variable frequency centrifugal fan) through a cooling air duct to draw cold air into the air-cooled box 21. During operation, room temperature air is drawn into the lower part of the air-cooled box 21 by the fan 6, flows upward along the baffle 24 in the gap of the semi-coke feeding pipe 11, and flows out from the upper air-cooled outlet 23 after heat exchange. The initial air volume is 200 Nm per semi-coke feed pipe. 3 The estimated total air volume is 7200 Nm³ / h, and the cooling air stays in the air-cooled box 21 for a sufficient time to complete the heat exchange.

[0059] In this embodiment, a temperature sensor is installed at the air outlet 23 on the upper part of the air-cooled box 21 to measure the outlet air temperature in real time. Under initial operating conditions, the temperature of the semi-coke entering the air-cooled section 2 is approximately 600°C, and the outlet air temperature rises to approximately 130°C. During the commissioning process, by adjusting the frequency of the fan 6, the outlet air temperature is stabilized at around 120°C. At this time, the temperature of the semi-coke at the end of the air-cooled section 2 is measured to be approximately 250°C, indicating that the heat exchange effect of the air-cooled section 2 is significant.

[0060] In this embodiment, the cooling air (hot air) after heat exchange in the air-cooled section 2 is discharged through the air-cooled outlet 23 and used as the drying air for drying the coal entering the external heating pyrolysis furnace, so that the waste heat of the semi-coke collected in the air-cooled section 2 can be utilized, thereby improving the overall thermal efficiency of the system.

[0061] In this embodiment, a cooling airflow regulating valve 104 (electric valve) and a frequency converter-driven fan 6 are installed on the air inlet duct of the air-cooled box 21. The controller 10 adjusts the airflow based on the temperature feedback detected by the second temperature sensor 102, and the control principle is to maintain the outlet air temperature in the range of 120±10℃. On the one hand, this ensures that the semi-coke is cooled to a suitable temperature (<300℃) to avoid the generation of a large amount of steam in the subsequent water-cooling section 3; on the other hand, it protects the fan 6 and the duct from overheating. During the trial operation, it was found that the increase in the amount of raw material caused T B When the detected temperature rises to 150℃, the controller 10 increases the frequency of the fan 6 by 10%, and the outlet air temperature quickly drops back to 120℃. The semi-coke temperature also decreases accordingly, demonstrating a good control effect.

[0062] 3. Water-cooled section 3 configuration: In water-cooled section 3, the lower part (4.4 meters high) of the semi-coke feed pipe 11 passes through the cooling water tank 31. The cooling water tank 31 is a closed rectangular cylindrical container filled with circulating cooling water. The water level reaches more than 90% of the height of the semi-coke feed pipe 11 in water-cooled section 3, leaving only a small space at the top to prevent overflow. The outer surface of the semi-coke feed pipe 11 in water-cooled section 3 is welded with annular fins to increase the heat exchange area and improve the heat exchange effect. The circulating cooling water enters from the lower part of the cooling water tank 31 through a water distributor, indirectly exchanges heat with the semi-coke in the semi-coke feed pipe 11, and then overflows from the top to the water-cooled outlet 33. The cooling water is drawn out by the circulating pump 7 and enters the plate heat exchanger, where it exchanges heat and cools before returning to the cooling water tank 31, forming a closed-loop circulation. To ensure effective cooling, the inlet and outlet temperatures of the cooling water are designed to be 30℃ and 50℃ respectively, with a total flow rate of approximately 20 m³ / h, allowing the semi-coke to be cooled to below 80℃. The semi-coke discharge pipes 11 after the water-cooling section 3 are all connected to a sealed quenching buffer tank to isolate it from air. A coke pusher at the bottom of the quenching buffer tank continuously discharges the cooled semi-coke, which is then transported away via a belt conveyor.

[0063] In this embodiment, a third temperature sensor 103 is installed at the end of the semi-coke feed pipe 11 in the water-cooled section 3 to monitor the semi-coke discharge temperature; a thermometer is also installed at the water-cooled outlet 33 of the cooling water tank 31 to monitor the water temperature and prevent it from becoming too high. The circulating pump 7 is frequency-controlled, and a cooling water flow regulating valve 105 (electrically controlled valve) is installed on the cooling water circulation pipe upstream of the water-cooled inlet 32. The controller 10 uses the temperature detected by the third temperature sensor 103 as the main control variable, supplemented by water temperature monitoring. When the temperature detected by the third temperature sensor 103 is close to or exceeds 80°C, the controller 10 increases the water flow or decreases the inlet water temperature (e.g., by turning on the backup cooling tower to lower the water temperature) to increase the cooling intensity; when the temperature detected by the third temperature sensor 103 is much lower than the target temperature (e.g., below 50°C) and the water temperature is low, the speed of the circulating pump 7 is appropriately reduced to save energy. When the water temperature is too high (e.g., >60°C, indicating insufficient water cooling heat exchange), an alarm is triggered, prompting a check of the operating conditions of the air-cooled section 2 and the water-cooled section 3.

[0064] 4. Coordinated Control and Cooling Path Management: The controller 10 integrates the temperature measurement information from the first temperature sensor 101, the second temperature sensor 102, and the third temperature sensor 103, and interlocks them to achieve gradient control of semi-coke cooling. In this embodiment, the target gradient temperature is set as follows: Temperature value T measured by the first temperature sensor 101... A Within the range of 500±50℃ Figure 4 (Left vertical line), temperature value measured by the second temperature sensor 102 (T) B Within the range of 280±20℃ Figure 4 (middle vertical line), third temperature sensor 103 temperature measurement value T C Less than 80℃ Figure 4 (Right vertical line).

[0065] If T A A temperature below 450℃ indicates that the semi-coke has not resided in the high-temperature zone for a sufficiently short time or that the pyrolysis process has not released enough heat. To prevent excessively high tar content in the discharged material, controller 10 slows down the feeding speed (coke pusher decelerates) to extend the residence time of the semi-coke in transition zone 1, thus increasing the T... A The temperature is rising. Simultaneously monitor whether the raw coal gas outlet 25 is unobstructed to prevent abnormal temperature in transition section 1 due to untimely gas discharge.

[0066] If T B High and T C The temperature also rises, indicating insufficient air cooling causing more heat to enter the water cooling section 3. The controller 10 automatically increases the airflow in the air cooling section 2 to prioritize and enhance air cooling, reducing the burden on the water cooling section 3, thus increasing the temperature of the T section. B Reduce to the target range.

[0067] Through multi-point coordinated adjustment, a smooth cooling curve is ensured throughout the semi-coke feeding process (e.g., Figure 4 As shown in the figure, the semi-coke discharge temperature is always safely controlled regardless of load changes.

[0068] Actual operation results show that in this embodiment, the semi-coke discharge temperature remains stable at around 75℃, water consumption is reduced by more than 60% compared to the traditional water quenching method, and the hot air recovered from the waste heat in the air-cooling section 2 is used for drying the coal entering the furnace, improving coal processing capacity. The finished semi-coke has intact particle size, with an average particle size maintained at around 6mm, and the crushing rate is significantly reduced.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A three-stage continuous cooling structure for a low-rank coal pyrolysis device, wherein the low-rank coal pyrolysis device includes a high-temperature dry distillation section, the high-temperature dry distillation section includes multiple spaced combustion chambers and dry distillation chambers, and a coke pushing and discharging mechanism is provided below the low-rank coal pyrolysis device; characterized in that, The three-stage continuous cooling structure includes a transition section, an air-cooled section, and a water-cooled section. The bottom of each distillation chamber is connected to multiple semi-coke feeding pipes. The transition section, air-cooled section, and water-cooled section are arranged from top to bottom along the semi-coke feeding pipes. The coke quenching buffer section is equipped with a coke quenching buffer tank, and the lower end of the semi-coke feeding pipe is connected to the coke quenching buffer tank. The air-cooled section includes an air-cooled box located around the semi-coke feeding pipe, and the water-cooled section includes a cooling water tank located around the semi-coke feeding pipe. The coke discharge port at the bottom of the coke quenching buffer tank is connected to the coke pushing and discharging mechanism.

2. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 1, characterized in that, Multiple rows of semi-coke feeding pipes are arranged in parallel to form a semi-coke feeding pipe bundle. The semi-coke feeding pipes are made of heat-resistant alloy steel.

3. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 1, characterized in that, The transition section is connected to the air-cooled section at the semi-coke feeding pipe with a raw coal gas outlet; the air-cooled box has an air-cooled inlet at the bottom and an air-cooled outlet at the top, and multiple baffles are arranged along the height inside the air-cooled box; the air-cooled inlet is connected to the atmosphere, and the air-cooled outlet is connected to the air inlet of the blower.

4. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 1, characterized in that, The cooling water tank has a water-cooled inlet at the lower end of one end and a water-cooled outlet at the upper part of the other end; the water-cooled inlet and the water-cooled outlet are connected by a cooling water circulation pipe outside the cooling water tank, and a circulation pump is installed on the cooling water circulation pipe.

5. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 1, characterized in that, The outer wall of the semi-coke feed pipe located in the cooling section is provided with annular ribs.

6. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 1, characterized in that, The coke quenching buffer tank is a closed tank. A coke pushing and discharging mechanism is provided at the coke discharge port at the bottom of the coke quenching buffer tank. The coke pushing and discharging mechanism is a sealed discharge valve or a coke pushing device.

7. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 1, characterized in that, It also includes a semi-coke cooling control system; the semi-coke cooling control system consists of a first temperature sensor, a second temperature sensor, a third temperature sensor, a cooling airflow regulating device, a cooling waterflow regulating device, and a controller; the first temperature sensor is located at the bottom of the semi-coke feeding pipe in the transition section, the second temperature sensor is located at the bottom of the semi-coke feeding pipe in the air-cooled section, and the third temperature sensor is located at the bottom of the semi-coke feeding pipe in the water-cooled section; the cooling airflow regulating device is located on the cooling air duct downstream of the air-cooled outlet, and the cooling waterflow regulating device is located on the cooling water circulation duct upstream of the water-cooled inlet; the first temperature sensor, the second temperature sensor, the third temperature sensor, the cooling airflow regulating device, and the cooling waterflow regulating device are respectively connected to the controller; the controller is also connected to the coke pushing and discharging device.

8. The three-stage continuous cooling structure of a low-rank coal pyrolysis device according to claim 7, characterized in that, The cooling airflow regulating device is a frequency converter-controlled fan and / or a cooling airflow regulating valve; the cooling water flow regulating device is a frequency converter-controlled circulating pump and / or a cooling water flow regulating valve.

9. A semi-coke cooling control method, based on the three-stage continuous cooling structure of the low-rank coal pyrolysis device as described in any one of claims 1 to 8; characterized in that, The process includes the following: 1) In the low-rank coal pyrolysis unit, the semi-coke generated after the coal is pyrolyzed in the high-temperature dry distillation section enters each semi-coke feed pipe in the transition section and moves slowly downward. After flowing through the transition section, the temperature of the semi-coke drops from above 700℃ to 500-600℃. Before the semi-coke enters the air-cooling section, the residual volatile matter in the semi-coke is discharged through the raw coal gas outlet. 2) After initial cooling, the semi-coke enters the air-cooling section and continues to move down along the semi-coke feeding pipe. Air is introduced into the air-cooling box by a fan as cooling air. The cooling air flows upward along the multi-layer baffle plate. During this process, it indirectly exchanges heat with the semi-coke in the semi-coke feeding pipe. After passing through the air-cooling section, the temperature of the semi-coke drops to below 300℃. 3) After being cooled by air, the semi-coke enters the water cooling section and continues to move down along the semi-coke feeding pipe. The circulating cooling water is introduced into the cooling water tank by the circulating pump. The cooling water and the semi-coke in the semi-coke feeding pipe exchange heat indirectly. After passing through the water cooling section, the temperature of the semi-coke drops to below 80℃. 4) The semi-coke after water cooling enters the coke quenching buffer section and is discharged quantitatively through the coke pushing and discharging device at the bottom of the coke quenching buffer tank.

10. A semi-coke cooling control method according to claim 9, characterized in that, A semi-coke cooling control system is used to control the continuous and stable cooling of the semi-coke, which specifically includes the following process: 1) The half-coke temperature at the end of the transition section is detected in real time using the first temperature sensor, the half-coke temperature at the end of the air-cooled section is detected in real time using the second temperature sensor, and the half-coke temperature at the end of the water-cooled section is detected in real time using the third temperature sensor. 2) Cooling airflow adjustment: The controller compares the detection value of the second temperature sensor with the preset value of the semi-coke temperature. By adjusting the power of the variable frequency fan or adjusting the opening of the cooling airflow control valve, the airflow into the air-cooled box is adjusted until the detection value of the second temperature sensor is within the range of the preset value of the semi-coke temperature. 3) Cooling water volume adjustment: The controller compares the detection value of the third temperature sensor with the second preset value of half coke temperature, and adjusts the cooling water flow rate into the cooling water tank by adjusting the power of the variable frequency circulating pump or adjusting the opening of the cooling water flow control valve until the detection value of the third temperature sensor is within the range of the second preset value of half coke temperature. 4) Feeding rate adjustment: Based on the real-time detection values ​​of the first and second temperature sensors, determine the combined trend of the semi-coke temperature at the end of the transition section and the end of the air-cooling section, and adjust the feeding rate of the semi-coke or the opening and closing cycle of the coke discharge port using the coke pushing and discharging device; by adjusting the residence time of the semi-coke in the transition section and the air-cooling section, ensure that the semi-coke temperature when entering the water-cooling section meets the requirements. 5) Temperature Coordinated Regulation: The detection values ​​of the first, second, and third temperature sensors are compared with the preset gradient target temperature in the controller. The controller interlocks and controls the cooling airflow regulation device, cooling waterflow regulation device, and coke pushing and discharging device to coordinately adjust the cooling airflow, cooling waterflow, and feeding rate. This makes the semi-coke temperature at the end of the transition section, the end of the air-cooled section, and the end of the water-cooled section gradually approach the gradient target temperature, forming a smooth semi-coke cooling path and stabilizing the semi-coke discharge temperature within the set range.

Images