A de- tar purification system and de-tar purification process

Abstract

The application discloses a tar removal and purification system and a tar removal and purification process. The tar removal and purification system comprises a cyclone heat exchanger, the cyclone heat exchanger comprises an outer cylinder and an inner cylinder embedded in the outer cylinder, a gas flow channel is formed between the inner cylinder and the outer cylinder, a gas inlet of the cyclone heat exchanger is arranged at the upper end of the side wall of the outer cylinder and is communicated with the gas flow channel, one end of the gas flow channel close to the gas inlet is closed, the gas flow channel is communicated with the inner cavity of the inner cylinder through a through hole on the wall surface of the inner cylinder, and a gas outlet of the cyclone heat exchanger is arranged at the upper end of the inner cylinder. A first heat exchange cavity for the flow of a cooling medium is arranged on the side wall of the outer cylinder. The tar removal and purification system and the tar removal and purification process can efficiently remove tar components in the fuel gas, do not produce tar-containing waste water, are not prone to causing the problem of tar blocking the pipeline, and can realize the effective recycling of the sensible heat of the high-temperature fuel gas.

Description

Technical Field

[0001] This invention relates to a purification system and a tar removal purification process for tar-containing fuel gas. Background Technology

[0002] Currently, landfilling and incineration are the main methods for treating organic solid waste. However, with the increasing scarcity of land resources in China and the urgent need for high-value utilization of solid waste, there has been a growing number of attempts in recent years to treat organic solid waste based on pyrolysis gasification technology. Pyrolysis gasification technology utilizes the thermal instability of organic matter in solid waste to pyrolyze and semi-coke gasify it, causing the organic matter to decompose and form various new combustible gases. The resulting gas can be used as fuel gas, for heating, co-firing, power generation, etc., achieving both effective harmlessness and volume reduction. Compared to direct incineration, it has a higher resource utilization capacity, significantly improving the economics and flexibility of projects. Currently, the development of pyrolysis gasification technology is mainly limited by the relatively low energy conversion efficiency of the system and the difficulty in removing tar from the gas. The gas produced after organic solid waste passes through a pyrolysis reactor and gasifier typically reaches temperatures above 700℃. Given that the boiling point of tar in the gas is generally around 200-400℃, most current purification technologies involve directly spraying the gasified gas to remove tar and stabilize it to room temperature, or utilizing waste heat to lower the gas to above the tar boiling point before spraying it in a spray chamber to remove tar and cool it to room temperature. This spraying method is relatively crude and simple. While it effectively cools and purifies the gas, its waste heat recovery efficiency is low, resulting in low system energy conversion efficiency. Furthermore, the large amount of tar-containing wastewater generated during spraying can easily cause secondary pollution. Therefore, developing new and efficient waste heat recovery and purification systems is of great significance for the development of pyrolysis gasification technology.

[0003] Chinese patent CN214300020U discloses a biogas purifier, which includes multiple cooling chambers, a gas purification group, and a tar collection group. Tar-containing gas passes sequentially through a cooling chamber containing a spray head and a filter screen in an intermediate pipe and an external pipe containing a spiral auger. The cooling chamber is cooled by cold water, so that the tar-containing gas is purified by four different methods: cooling, swirling, showering, and filtration, to obtain high-purity gas. The device can effectively cool down the gas, but the large number of pipes results in small pipe diameters, which makes the pipes easy to clog with tar. In addition, the spraying generates tar-containing wastewater that is difficult to treat, causing secondary pollution. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of existing technologies that use spraying to remove tar from fuel gas, such as generating difficult-to-treat tar-containing wastewater, causing secondary pollution, and having small pipe diameters that easily clog pipes with tar. This invention provides a tar removal purification system and process. The tar removal purification system and process of this invention efficiently remove tar components from fuel gas without generating tar-containing wastewater and are less prone to tar clogging of pipes; simultaneously, they achieve effective recovery and utilization of the sensible heat of the high-temperature fuel gas.

[0005] The present invention solves the above-mentioned technical problems by adopting the following technical solutions:

[0006] This invention provides a tar removal and purification system, comprising a cyclone heat exchanger, the cyclone heat exchanger including an outer cylinder and an inner cylinder embedded within the outer cylinder, an airflow channel forming between the inner cylinder and the outer cylinder, a gas inlet of the cyclone heat exchanger located at the upper end of the side wall of the outer cylinder and communicating with the airflow channel, the end of the airflow channel near the gas inlet being closed, the airflow channel communicating with the inner cavity of the inner cylinder through a through hole on the wall surface of the inner cylinder, and a gas outlet of the cyclone heat exchanger located at the upper end of the inner cylinder; the height-to-diameter ratio of the outer cylinder is not less than 5:1, the ratio of the distance between the gas inlet and the through hole to the height of the outer cylinder is in the range of 0.5 to 0.8; a first heat exchange cavity for the flow of cooling medium is provided on the side wall of the outer cylinder;

[0007] A single-stage tube heat exchanger, wherein the tube-side inlet of the single-stage tube heat exchanger is connected to the gas outlet, and the tube diameter of the single-stage tube heat exchanger is 40-70 mm;

[0008] And a secondary tube heat exchanger, wherein the tube-side inlet of the secondary tube heat exchanger is connected to the tube-side outlet of the primary tube heat exchanger, and the tube diameter of the secondary tube heat exchanger is 15-40 mm.

[0009] Organic solid waste generates high-temperature fuel gas at temperatures above 700°C after passing through a pyrolysis reactor and gasifier. This high-temperature fuel gas contains highly viscous, high-boiling-point heavy tar components containing benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings, which are very difficult to remove. High-temperature fuel gas containing the aforementioned heavy tar components enters the gas flow channel through a tangential gas inlet. Within the gas flow channel, it swirls downwards along the walls of the outer and inner cylinders. During this process, the high-boiling-point heavy tar is swirled to the inner wall of the outer cylinder, where it condenses and liquefies into tar droplets. The height-to-diameter ratio defined in this invention ensures thorough separation of the heavy tar from the fuel gas. The fuel gas enters the inner cylinder cavity through the gas flow channel via a perforation on the inner cylinder and exits the cyclone heat exchanger through the gas outlet at the upper end of the inner cylinder. This achieves the removal of high-boiling-point heavy tar from the high-temperature fuel gas without generating tar-containing wastewater. Simultaneously, the swirling motion of the high-temperature fuel gas within the circulation channel pushes the tar droplets condensed on the inner wall of the outer cylinder downwards, preventing tar from adhering to the inner wall and causing channel blockage, and effectively recovering heat from the high-temperature fuel gas.

[0010] Following the cyclone heat exchanger are a primary and a secondary shell-and-tube heat exchanger, enabling the separation of high-boiling-point heavy tar in the cyclone heat exchanger, low-boiling-point heavy tar in the primary shell-and-tube heat exchanger, and light tar in the secondary shell-and-tube heat exchanger. This staged separation of tar reduces the risk of pipe blockage, especially during the separation of high-boiling-point heavy tar. Furthermore, the use of smaller-diameter shell-and-tube heat exchangers in the light tar separation process increases the heat exchange area and improves heat exchange efficiency. Finally, it allows for the separate utilization of tar by different grades.

[0011] In this invention, preferably, the height-to-diameter ratio of the outer cylinder is (5-10):1.

[0012] The preferred height-to-diameter ratio described above is more advantageous for the manufacture and installation of the equipment.

[0013] In this invention, preferably, the bottom of the side wall of the outer cylinder is provided with a first cooling medium inlet, and the top of the side wall of the outer cylinder is provided with a first cooling medium outlet. Both the first cooling medium inlet and the first cooling medium outlet are connected to the first heat exchange cavity. The bottom is the end away from the gas outlet, and the top is the end close to the gas outlet.

[0014] The cooling medium enters the first heat exchange cavity through the first cooling medium inlet at the bottom of the outer cylinder sidewall and flows out through the first cooling medium outlet at the top of the outer cylinder sidewall, realizing the bottom entry and top exit of the cooling medium, which can make full use of the heat exchange area of ​​the first heat exchange cavity.

[0015] In this invention, preferably, the outer cylinder has a conical tar outlet at the end away from the gas outlet.

[0016] The high-boiling-point heavy tar that swirls onto the inner wall of the outer cylinder is discharged through the conical tar outlet, which facilitates the smooth discharge and collection of the tar.

[0017] In this invention, preferably, the inner wall material of the outer cylinder and / or the inner wall material of the inner cylinder is stainless steel.

[0018] The inner wall material of the outer cylinder and inner cylinder specified in this invention makes the inner wall surface smoother, thereby allowing the high-viscosity, high-boiling-point heavy tar to flow down more smoothly.

[0019] In this invention, preferably, the through hole is located on the bottom wall of the inner cylinder. The bottom wall is the wall surface of the inner cylinder at the end away from the gas outlet.

[0020] The through-hole is located on the bottom wall of the inner cylinder, which can make full use of the length of the airflow channel, so that the gas flows downward in the airflow channel to achieve full separation of heavy tar.

[0021] In this invention, preferably, the ratio of the distance between the gas inlet and the through hole to the height of the outer cylinder is in the range of 0.7 to 0.8.

[0022] The preferred range defined by the ratio of the distance between the gas inlet and the through hole to the height of the outer cylinder can make full use of the height of the outer cylinder, so that the heavy tar in the gas is separated during the downward swirling of the gas flow.

[0023] In this invention, preferably, a second heat exchange cavity for the flow of cooling medium is provided in the interlayer of the side wall of the inner cylinder.

[0024] The second heat exchange cavity can further exchange heat with the gas flowing in the inner cylinder cavity, thereby further improving the heat recovery efficiency; at the same time, the gas further exchanges heat with the wall surface during the flow of the gas in the inner cylinder cavity, thus separating the heavy tar.

[0025] In this invention, preferably, the ratio of the inner diameter of the inner cylinder to the inner diameter of the outer cylinder is 0.2 to 0.6, more preferably 0.25 to 0.5.

[0026] The inner diameter ratio range of the inner and outer cylinders defined above in this invention allows the gas to maintain good turbulent flow within the cavity of the inner cylinder, thereby enhancing heat exchange with the inner cylinder wall and further separating the heavy tar in the gas to the inner wall of the inner cylinder; at the same time, the heavy tar condensed into small droplets on the inner wall of the inner cylinder is less likely to clog the inner cylinder.

[0027] In this invention, preferably, the inner cylinder has a second cooling medium inlet and a second cooling medium outlet on its side wall. The second cooling medium inlet is connected to one end of the cooling medium conveying channel, and the other end of the cooling medium conveying channel is located at the bottom of the second heat exchange cavity, the bottom being the end away from the gas outlet.

[0028] The cooling medium is transported to the bottom of the second heat exchange cavity through the cooling medium transport channel, realizing the bottom entry and top exit of the cooling medium and fully carrying out heat exchange.

[0029] In this invention, the tube diameter of the first-stage tube heat exchanger is preferably 45-55 mm, for example 50 mm; the tube diameter of the second-stage tube heat exchanger is preferably 18-25 mm, for example 20 mm.

[0030] The present invention also provides a tar removal purification process, which includes the following steps: tar-containing gas enters the tar removal purification system described above through the gas inlet, wherein the tar-containing gas contains high-boiling-point heavy tar with a boiling point >300℃, low-boiling-point heavy tar with a boiling point of 200-300℃, and light tar with a boiling point <200℃.

[0031] The flow velocity of the tar-containing gas in the gas inlet is 10-15 m / s, the gas temperature at the gas outlet is 260-350℃, and the residence time of the gas in the cyclone heat exchanger is 10-15 s.

[0032] The gas temperature at the tube-side outlet of the first-stage shell-and-tube heat exchanger is 170–240°C.

[0033] The gas temperature at the tube outlet of the two-stage tube heat exchanger is 30–50°C.

[0034] In this invention, preferably, the tar-containing gas is a combustible gas obtained by pyrolysis and gasification of organic solid waste.

[0035] The organic solid waste refers to solid and semi-solid organic waste that pollutes the environment and is generated by humans in production, construction, daily life, and other activities. The organic matter content of the organic solid waste is typically above 20%.

[0036] In this invention, tar refers to polycyclic aromatic hydrocarbons with a molecular weight greater than benzene and / or heterocyclic aromatic hydrocarbons containing at least one of nitrogen, oxygen, and sulfur elements.

[0037] In this invention, the total tar content in the tar-containing gas is preferably 200–800 mg / Nm³. 3 More preferably 500 mg / Nm 3 .

[0038] In this invention, the mass ratio of the high-boiling-point heavy tar, the low-boiling-point heavy tar, and the light tar in the tar-containing gas is preferably (40-60):(20-40):(10-30), and more preferably 50:30:20.

[0039] In this invention, preferably, the high-boiling-point heavy tar is tar with a boiling point of 350°C or higher.

[0040] In this invention, preferably, the low-boiling-point heavy tar is tar with a boiling point of 250-300°C.

[0041] In this invention, the temperature of the gas at the gas outlet is preferably 280-320°C, and more preferably 300°C.

[0042] As is generally understood by those skilled in the art, the gas outlet temperature of a heat exchanger is determined by the heat exchange area, the coolant flow rate, and the inlet and outlet temperatures of the coolant.

[0043] Preferably, the inlet temperature of the cooling medium in the first heat exchange cavity and the inlet temperature of the cooling medium in the second heat exchange cavity of the cyclone heat exchanger are independently 20-40°C, more preferably 22-32°C, and even more preferably 28°C.

[0044] Preferably, the outlet temperature of the cooling medium in the first heat exchange cavity and the outlet temperature of the cooling medium in the second heat exchange cavity of the cyclone heat exchanger are independently 75-85°C, more preferably 77-83°C, and even more preferably 80°C.

[0045] The heat exchange area of ​​the first heat exchange cavity and the second heat exchange cavity, as well as the flow rate of the cooling medium in the first heat exchange cavity and the second heat exchange cavity, can be obtained through conventional calculations in the art based on the gas inlet and outlet temperatures, gas flow rate, and cooling medium inlet and outlet temperatures.

[0046] In this invention, the residence time of the gas in the cyclone heat exchanger is preferably 12 to 15 seconds.

[0047] In this invention, the gas temperature at the tube outlet of the first-stage tube heat exchanger is preferably 190–220°C, and more preferably 200°C.

[0048] Those skilled in the art generally understand that the gas outlet temperature in a shell-and-tube heat exchanger is determined by the inlet and outlet temperatures of the cooling medium, the flow rate of the cooling medium, and the heat exchange area.

[0049] The inlet temperature of the cooling medium in the primary tube heat exchanger is preferably 20–40°C, more preferably 22–32°C, and even more preferably 28°C.

[0050] The outlet temperature of the cooling medium in the primary tube heat exchanger is preferably 60-80°C, more preferably 65-75°C, and even more preferably 70°C.

[0051] The flow rate of the cooling medium and the heat exchange area in the first-stage tube heat exchanger can be calculated conventionally in the art based on the inlet and outlet temperatures of the gas in the tubes and the inlet and outlet temperatures of the cooling medium.

[0052] In this invention, the gas temperature at the tube outlet of the two-stage tube heat exchanger is preferably 35-45°C, and more preferably 40°C.

[0053] The inlet temperature of the cooling medium in the secondary tube heat exchanger is preferably 20–40°C, more preferably 22–32°C, and even more preferably 28°C.

[0054] The outlet temperature of the cooling medium in the secondary tube heat exchanger is preferably 45-55°C, more preferably 48-53°C, and even more preferably 50°C.

[0055] Similarly, the heat exchange area and cooling medium flow rate of a two-stage tube heat exchanger can be obtained through conventional calculations based on the inlet and outlet temperatures of the tube-side gas and the inlet and outlet temperatures of the cooling medium.

[0056] In this invention, preferably, the inner wall temperature of the outer cylinder and the inner wall temperature of the inner cylinder are independently 80-150°C, more preferably independently 80-100°C.

[0057] The temperature of the inner wall surfaces of the outer and inner cylinders as defined by the present invention can maintain good fluidity of high-boiling-point heavy tar in a cyclone heat exchanger.

[0058] In this invention, preferably, the temperature of the inner wall surface of the tubes of the first-stage tube heat exchanger is 70-90°C, more preferably 75-85°C, for example 80°C.

[0059] The tube inner wall temperature of the first-stage tube heat exchanger defined by the present invention enables the low-boiling-point heavy tar to condense and separate in the first-stage tube heat exchanger, and ensures that the low-boiling-point heavy tar has good fluidity in the tubes.

[0060] In this invention, preferably, the inner wall temperature of the tubes in the secondary tube heat exchanger is 50-70°C, for example, 65°C.

[0061] The inner wall temperature of the tubes defined by the present invention causes the light tar in the fuel gas to condense and liquefy into small droplets, thus separating it from the fuel gas.

[0062] Those skilled in the art will understand that the temperature of the inner wall surface at the gas outlet is necessarily lower than the temperature of the outlet gas. The inner wall surface temperatures mentioned above in this invention are not the temperatures of the gas outlet section.

[0063] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0064] The reagents and raw materials used in this invention are all commercially available.

[0065] The positive and progressive effects of this invention are as follows: the tar removal purification system and process of this invention are suitable for treating fuel gas containing high-boiling-point heavy tar. While efficiently removing tar components from the fuel gas, it does not generate tar-containing wastewater and is less prone to tar clogging of pipelines; simultaneously, it achieves effective recovery and utilization of the sensible heat of the high-temperature fuel gas; and it can reduce the tar content in the fuel gas to 50 mg / Nm³. 3 The gas purified after decoking meets the intake requirements for internal combustion engine power generation. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the cyclone heat exchanger structure in Example 1;

[0067] Figure 2 This is a schematic diagram of the tar removal and purification system in Example 1.

[0068] Figure Labels

[0069] 1-Cyclone heat exchanger; 11-Outer cylinder; 111-First heat exchange cavity; 112-First cooling medium outlet; 113-First cooling medium inlet; 114-Tar outlet; 12-Inner cylinder; 121-Through hole; 122-Inner cavity; 123-Second heat exchange cavity; 124-Second cooling medium outlet; 125-Second cooling medium inlet; 126-Cooling medium conveying channel; 13-Airflow channel; 14-Gas inlet; 15-Gas outlet; H-Height of outer cylinder; h-Distance between gas inlet and through hole; 2-First-stage tube heat exchanger; 3-Second-stage tube heat exchanger. Detailed Implementation

[0070] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0071] Example 1

[0072] Reference Figure 1As shown, the cyclone heat exchanger 1 in this embodiment includes an outer cylinder 11 and an inner cylinder 12 embedded in the outer cylinder 11. An airflow channel 13 is formed between the inner cylinder 12 and the outer cylinder 11. The gas inlet 14 of the cyclone heat exchanger 1 is located at the upper end of the side wall of the outer cylinder 11 and communicates with the airflow channel 13. The end of the airflow channel 13 near the gas inlet 14 is closed. The airflow channel 13 communicates with the inner cavity 122 of the inner cylinder 12 through a through hole 121 on the wall of the inner cylinder 12. The through hole 121 is located on the bottom wall of the inner cylinder 12. The gas outlet 15 of the cyclone heat exchanger 1 is located at the upper end of the inner cylinder 12. A first heat exchange cavity 111 for the cooling medium to circulate is provided on the side wall of the outer cylinder 11. A first cooling medium inlet 113 is provided at the bottom of the side wall of the outer cylinder 11. The top of the outer cylinder 11 is provided with a first cooling medium outlet 112, and both the first cooling medium inlet 113 and the first cooling medium outlet 112 are connected to the first heat exchange cavity 111. The outer cylinder 11 is provided with a conical tar outlet 114 at the end away from the gas outlet 15. The inner cylinder 12 is provided with a second heat exchange cavity 123 for the flow of cooling medium on its side wall. The upper end of the side wall of the inner cylinder 12 is provided with a second cooling medium inlet 125 and a second cooling medium outlet 124. The second cooling medium inlet 125 is connected to one end of the cooling medium conveying channel 126, which is located inside the second heat exchange cavity 123. The other end of the cooling medium conveying channel 126 extends to the bottom of the second heat exchange cavity 123. The second cooling medium outlet 124 is connected to the second heat exchange cavity 123.

[0073] The outer cylinder has a height H of 5000mm, an inner diameter of 600mm, and a height-to-diameter ratio of 8.3:1. The ratio of the distance h between the gas inlet and the through hole to the height H of the outer cylinder is in the range of 0.5 to 0.8. The ratio of the inner diameter of the inner cylinder 12 to the inner diameter of the outer cylinder 11 is 0.25 to 0.5.

[0074] Reference Figure 2 As shown, the tar removal and purification system includes a cyclone heat exchanger 1, a primary tube heat exchanger 2, and a secondary tube heat exchanger 3. The tube-side inlet of the primary tube heat exchanger 2 is connected to the gas outlet 15 of the cyclone heat exchanger 1, and the tube-side outlet of the primary tube heat exchanger 2 is connected to the tube-side inlet of the secondary tube heat exchanger 3. The tube diameter of the primary tube heat exchanger 2 is 50 mm, and the tube diameter of the secondary tube heat exchanger 3 is 20 mm.

[0075] Organic solid waste, after passing through a pyrolysis reactor and gasifier, generates high-temperature fuel gas exceeding 700°C. This high-temperature fuel gas contains highly viscous, high-boiling-point heavy tar components containing benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings, which are extremely difficult to remove. The high-temperature fuel gas containing these heavy tar components enters the gas flow channel 13 through a tangential gas inlet 14. Within the gas flow channel 13, it swirls downwards along the walls of the outer cylinder 11 and the inner cylinder 12. During this process, the high-boiling-point heavy tar is swirled to the inner wall of the outer cylinder 11. The inner wall of the outer cylinder 11 is cooled by the cooling medium in the first heat exchange cavity 111, condensing the high-boiling-point heavy tar swirling onto it into tar droplets. The height-to-diameter ratio specified in this invention ensures thorough separation of the heavy tar from the fuel gas. The gas enters the inner cavity 122 of the inner cylinder 12 through the through hole 121 on the bottom wall of the inner cylinder 12 via the airflow channel 13. The gas undergoes turbulent motion within the inner cavity 122, where residual high-boiling-point heavy tar condenses and liquefies into tar droplets upon contact with the inner wall surface of the inner cylinder 12. The inner wall surface of the inner cylinder 12 is cooled by the cooling medium in the second heat exchange cavity 123. The gas exits the cyclone heat exchanger 1 through the gas outlet 15, which communicates with the inner cavity 122. The cooling medium in the first heat exchange cavity 111 enters through the first cooling medium inlet 113, exchanges heat with the outer cylinder 11 wall inside the first heat exchange cavity 111, and then flows out through the first cooling medium outlet 112. The cooling medium in the second heat exchange cavity 123 enters the cooling medium conveying channel 126 through the second heat exchange medium inlet, and is conveyed to the bottom of the second heat exchange cavity 123 by the cooling medium unblocking channel. Then, the cooling medium flows upward from the bottom of the second heat exchange cavity 123 and flows out through the second cooling medium outlet 124, realizing the bottom entry and top exit of the cooling medium.

[0076] The gas from gas outlet 15 enters the tube side of the first-stage tube heat exchanger 2, where it is further cooled to condense and liquefy the low-boiling-point heavy tar in the gas, thus separating it from the gas. The gas discharged from the tube side outlet of the first-stage tube heat exchanger 2 enters the second-stage tube heat exchanger 3, where it is further cooled to condense and liquefy the light tar in it, thus separating it from the gas.

[0077] Example 2

[0078] Continue to refer to Figure 1 and Figure 2 As shown, the tar removal and purification process in this embodiment is carried out in the tar removal and purification system of Example 1, specifically as follows: Organic solid waste raw materials (including waste screening materials such as rubber, textiles, and plastics, as well as agricultural and forestry waste) are processed through a pyrolysis and gasification system to generate high-temperature fuel gas at approximately 700°C, with a tar content of 500 mg / Nm³. 3The gas consists of 50% high-boiling-point heavy tar (boiling point > 300℃), 30% low-boiling-point heavy tar (boiling point 200-300℃), and 20% light tar. After exiting the gasifier, the gas enters a high-temperature ceramic fiber filter for high-temperature dust removal, and its temperature drops to around 600℃. It then enters the cyclone heat exchanger 1 through the tangential gas inlet 14 at a speed of approximately 10-15 m / s (gas velocity at inlet 14). Cooling water flowing in the first heat exchange cavity 111 and the second heat exchange cavity 123 maintains the temperature of the inner wall of the outer cylinder 11 and the inner wall of the inner cylinder 12 at around 100℃. The gas flows downwards in the gas channel, and during this process, the heavy tar that condenses first is swirled to the inner wall of the outer cylinder 11 of the heat exchanger. At this temperature, the high-boiling-point heavy tar... The heavy tar maintains good fluidity. Under its own gravity and the blowing effect of the gas flow direction, the tar flows downward and exits through the tar outlet 114. The gas enters the inner cavity 122 of the inner cylinder 12 through the gas flow channel 13 and undergoes further heat exchange in the inner cavity 122. The remaining small amount of high-boiling-point heavy tar further condenses and liquefies, adhering to the inner wall of the inner cylinder 12 in the gas turbulence, flowing downward along the inner wall of the inner cylinder 12 and exiting through the tar outlet 114. The residence time of the gas in the cyclone heat exchanger 1 is 10-15 seconds. The inlet temperature of the cooling water is 28℃, and the outlet temperature of the cooling water is around 80℃. By controlling the cooling water flow rate and the heat exchange area, the temperature of the gas discharged from the gas outlet 15 of the cyclone heat exchanger 1 is reduced to around 300℃. After passing through the cyclone heat exchanger 1, the tar content is reduced from 500 mg / Nm³. 3 The concentration dropped to around 200 mg / Nm 3 about.

[0079] The 300°C gas discharged from gas outlet 15 of cyclone heat exchanger 1 enters the tube side of the first-stage tube heat exchanger 2, while cooling water flows through the shell side. During this process, the gas temperature drops from 300°C to 200°C. The inner wall temperature of the first-stage tube heat exchanger 2 remains around 85°C, the cooling water inlet temperature is around 28°C, and the outlet temperature is around 70°C. During the heat exchange and cooling process, heavy tar gradually cools and condenses on the inner wall of the tubes, flowing down the inner wall to the collection tank. The tar content in the gas exiting the first-stage tube heat exchanger decreases from 200 mg / Nm³. 3 The concentration further decreased to 100 mg / Nm 3 about.

[0080] The gas gas, at approximately 200°C, exiting from the tube side of the first-stage shell-and-tube heat exchanger 2, enters the second-stage shell-and-tube heat exchanger 3. Cooling water flows through the shell side, maintaining the inner wall temperature of the tubes at approximately 65°C. The cooling water inlet temperature is approximately 28°C, and the outlet temperature is approximately 50°C. The light tar gradually condenses and flows downwards into the recovery tank. The gas gas temperature at the tube side outlet of the second-stage shell-and-tube heat exchanger 3 drops to approximately 40°C, and the tar content in the gas gas decreases to 50 mg / Nm³.3 The tar removal rate reaches over 90%.

[0081] The gasified fuel gas is cooled through a three-stage heat exchanger, and large-molecule clusters of focused oil, heavy tar, and light tar are removed in stages as the gasified fuel gas is cooled to a usable temperature. The collected cooling water from the three stages is at a temperature of approximately 75 degrees Celsius, making full use of the heat in the cooling water. The tar collected in the tar tank is periodically fed into the incinerator for incineration, making full use of its heat while achieving harmless treatment.

[0082] The inventors discovered through research that the gas temperature at the gas outlet 15 of the cyclone heat exchanger 1 is lower than the range defined in this invention, making the outer and inner cavities 122 of the cyclone heat exchanger 1 prone to tar blockage. Similarly, the outlet gas temperatures of the first-stage tube heat exchanger 2 and the second-stage tube heat exchanger 3 are also lower than the range defined in this invention, making them prone to tar blockage.

[0083] When the flow velocity of the tar-containing gas at gas inlet 14 is less than 10 m / s or the residence time is insufficient, the separation efficiency of high-boiling-point heavy tar in cyclone heat exchanger 1 is significantly reduced.

Claims

1. A tar removal and purification system, characterized in that, It includes a cyclone heat exchanger, which comprises an outer cylinder and an inner cylinder embedded within the outer cylinder. An airflow channel is formed between the inner cylinder and the outer cylinder. The gas inlet of the cyclone heat exchanger is located at the upper end of the side wall of the outer cylinder and communicates with the airflow channel. The end of the airflow channel near the gas inlet is closed. The airflow channel communicates with the inner cavity of the inner cylinder through a through hole on the wall of the inner cylinder. The gas outlet of the cyclone heat exchanger is located at the upper end of the inner cylinder. The height-to-diameter ratio of the outer cylinder is not less than 5:1, and the ratio of the distance between the gas inlet and the through hole to the height of the outer cylinder is in the range of 0.5 to 0.

8. A first heat exchange cavity for the flow of cooling medium is provided on the side wall of the outer cylinder. A single-stage tube heat exchanger, wherein the tube-side inlet of the single-stage tube heat exchanger is connected to the gas outlet, and the tube diameter of the single-stage tube heat exchanger is 40~70mm; And a secondary tube heat exchanger, wherein the tube-side inlet of the secondary tube heat exchanger is connected to the tube-side outlet of the primary tube heat exchanger, and the tube diameter of the secondary tube heat exchanger is 15~40mm.

2. The tar removal and purification system as described in claim 1, characterized in that, The height-to-diameter ratio of the outer cylinder is (5~10):1; And / or, the bottom of the side wall of the outer cylinder is provided with a first cooling medium inlet, and the top of the side wall of the outer cylinder is provided with a first cooling medium outlet. The first cooling medium inlet and the first cooling medium outlet are both connected to the first heat exchange cavity. The bottom is the end away from the gas outlet, and the top is the end close to the gas outlet. And / or, the outer cylinder is provided with a conical tar outlet at the end away from the gas outlet; And / or, the inner wall material of the outer cylinder and / or the inner wall material of the inner cylinder is stainless steel.

3. The tar removal and purification system as described in claim 2, characterized in that, The height-to-diameter ratio of the outer cylinder is 8.3:

1.

4. The tar removal and purification system as described in claim 1, characterized in that, The through hole is located on the bottom wall of the inner cylinder; And / or, the ratio of the distance between the gas inlet and the through hole to the height of the outer cylinder is in the range of 0.7 to 0.8; And / or, the inner cylinder has a second heat exchange cavity on its side wall for the flow of cooling medium; And / or, the ratio of the inner diameter of the inner cylinder to the inner diameter of the outer cylinder is 0.2 to 0.

6.

5. The tar removal and purification system as described in claim 4, characterized in that, The upper end of the side wall of the inner cylinder is provided with a second cooling medium inlet and a second cooling medium outlet. The second cooling medium inlet is connected to one end of the cooling medium conveying channel, and the other end of the cooling medium conveying channel is located at the bottom of the second heat exchange cavity. The second cooling medium outlet is connected to the second heat exchange cavity, and the bottom is the end away from the gas outlet. And / or, the ratio of the inner diameter of the inner cylinder to the inner diameter of the outer cylinder is 0.25 to 0.

5.

6. The tar removal and purification system as described in claim 1, characterized in that, The tube diameter of the primary tube heat exchanger is 45~55mm; And / or, the diameter of the secondary tube heat exchanger is 18~25mm.

7. The tar removal and purification system as described in claim 6, characterized in that, The diameter of the tubes in the first-stage shell-and-tube heat exchanger is 50 mm. And / or, the diameter of the secondary tube heat exchanger is 20 mm.

8. A tar removal and purification process, characterized in that, The tar-containing gas enters through the gas inlet in the tar removal purification system according to any one of claims 1 to 7. The tar-containing gas contains high-boiling-point heavy tar with a boiling point >300°C, low-boiling-point heavy tar with a boiling point of 200~300°C, and light tar with a boiling point <200°C. The flow velocity of the tar-containing gas in the gas inlet is 10~15m / s, the gas temperature at the gas outlet is 260~350℃, and the residence time of the gas in the cyclone heat exchanger is 10~15s. The gas temperature at the tube-side outlet of the first-stage tube heat exchanger is 170~240℃; The gas temperature at the tube outlet of the two-stage tube heat exchanger is 30~50℃.

9. The tar removal and purification process as described in claim 8, characterized in that, The mass ratio of the high-boiling-point heavy tar, the low-boiling-point heavy tar, and the light tar in the tar-containing gas is (40~60):(20~40):(10~30). And / or, the total tar content in the tar-containing gas is 200~800 mg / Nm³. 3 ; And / or, the tar-containing gas is the gas obtained by pyrolysis and gasification of organic solid waste and then filtered by a ceramic fiber filter for dust removal; And / or, the gas temperature at the gas inlet is 500~700℃; And / or, the temperature of the gas at the gas outlet is 280~320°C; And / or, the residence time of the gas in the cyclone heat exchanger is 12-15 s.

10. The tar removal and purification process as described in claim 9, characterized in that, The mass ratio of the high-boiling-point heavy tar, the low-boiling-point heavy tar, and the light tar in the tar-containing gas is 50:30:

20. And / or, the total tar content in the tar-containing gas is 500 mg / Nm³. 3 ; And / or, the gas temperature at the gas inlet is 550~650℃; And / or, the temperature of the gas at the gas outlet is 300°C.

11. The tar removal and purification process as described in claim 10, characterized in that, The gas temperature at the gas inlet is 600°C.

12. The tar removal and purification process as described in claim 8, characterized in that, The gas temperature at the tube-side outlet of the first-stage tube heat exchanger is 190~220℃; And / or, the gas temperature at the tube outlet of the secondary tube heat exchanger is 35~45℃.

13. The tar removal and purification process as described in claim 12, characterized in that, The gas temperature at the tube-side outlet of the first-stage tube heat exchanger is 200°C. And / or, the gas temperature at the tube outlet of the secondary tube heat exchanger is 40°C.

14. The tar removal and purification process according to any one of claims 8-11, characterized in that, When the tar removal purification system includes a second heat exchange cavity, the inlet temperature of the cooling medium in the first heat exchange cavity and the inlet temperature of the cooling medium in the second heat exchange cavity are independently 20~40℃. And / or, when the tar removal purification system includes a second heat exchange cavity, the outlet temperature of the cooling medium in the first heat exchange cavity and the outlet temperature of the cooling medium in the second heat exchange cavity are independently 75~85°C.

15. The tar removal and purification process as described in claim 14, characterized in that, When the tar removal purification system includes the second heat exchange cavity, the inlet temperature of the cooling medium in the first heat exchange cavity and the inlet temperature of the cooling medium in the second heat exchange cavity are independently 22~32℃. And / or, when the tar removal purification system includes the second heat exchange cavity, the outlet temperature of the cooling medium in the first heat exchange cavity and the outlet temperature of the cooling medium in the second heat exchange cavity are independently 77~83°C.

16. The tar removal and purification process as described in claim 15, characterized in that, When the detar purification system includes the second heat exchange cavity, the inlet temperature of the cooling medium in the first heat exchange cavity and the inlet temperature of the cooling medium in the second heat exchange cavity are independently 28°C. And / or, when the tar removal purification system includes the second heat exchange cavity, the outlet temperature of the cooling medium in the first heat exchange cavity and the outlet temperature of the cooling medium in the second heat exchange cavity are independently 80°C.

17. The tar removal and purification process as described in claim 8, 12, or 13, characterized in that, The inlet temperature of the cooling medium in the first-stage tube heat exchanger is 20~40℃; And / or, the cooling medium outlet temperature of the first-stage tube heat exchanger is 60~80℃; And / or, the inlet temperature of the cooling medium in the secondary tube heat exchanger is 20~40℃; And / or, the cooling medium outlet temperature of the secondary tube heat exchanger is 45~55℃.

18. The tar removal and purification process as described in claim 17, characterized in that, The inlet temperature of the cooling medium in the first-stage tube heat exchanger is 22~32℃; And / or, the cooling medium outlet temperature of the first-stage tube heat exchanger is 65~75℃; And / or, the inlet temperature of the cooling medium in the secondary tube heat exchanger is 22~32℃; And / or, the cooling medium outlet temperature of the secondary tube heat exchanger is 48~53℃.

19. The tar removal and purification process as described in claim 18, characterized in that, The inlet temperature of the cooling medium in the first-stage tube heat exchanger is 28°C. And / or, the cooling medium outlet temperature of the first-stage tube heat exchanger is 70°C; And / or, the inlet temperature of the cooling medium in the secondary tube heat exchanger is 28°C; And / or, the cooling medium outlet temperature of the secondary tube heat exchanger is 50°C.

20. The tar removal and purification process according to any one of claims 8-13, characterized in that, The inner wall temperature of the outer cylinder and the inner wall temperature of the inner cylinder are independently 80~150℃; And / or, the temperature of the inner wall surface of the tubes in the first-stage tube heat exchanger is 70~90℃; And / or, the temperature of the inner wall surface of the tubes in the secondary tube heat exchanger is 50~70℃.

21. The tar removal and purification process as described in claim 20, characterized in that, The inner wall temperature of the outer cylinder and the inner wall temperature of the inner cylinder are independently 80~100℃; And / or, the inner wall temperature of the tubes in the first-stage tube heat exchanger is 75~85℃; And / or, the inner wall temperature of the tubes in the secondary tube heat exchanger is 65°C.

22. The tar removal and purification process as described in claim 21, characterized in that, The temperature of the inner wall surface of the tubes in the first-stage tube heat exchanger is 80℃.

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