Connecting structure of low-rank coal pyrolysis furnace medium temperature dry distillation section and high temperature dry distillation section

Abstract

This invention relates to the field of low-rank coal pyrolysis technology, and more particularly to a connection structure between the intermediate-temperature and high-temperature carbonization sections of a low-rank coal pyrolysis furnace. The intermediate-temperature section furnace body is surrounded by an intermediate-temperature section protective plate, and the high-temperature section furnace body is surrounded by a high-temperature section protective plate. The intermediate-temperature and high-temperature section protective plates are fixedly connected. A heat insulation component is installed between the intermediate-temperature section protective plate at the bottom of the intermediate-temperature section and the refractory lining. An expansion joint is provided between the furnace walls of the high-temperature and intermediate-temperature sections and filled with flexible, high-temperature resistant sealing material. This invention employs a rigid connection structure between the intermediate-temperature and high-temperature carbonization sections, utilizing a special thermal compensation and sealing mechanism to effectively compensate for thermal expansion and contraction and ensure excellent sealing performance at the connection. Compared with existing water-sealed connection structures, this fundamentally eliminates the adverse effects of water vapor on the pyrolysis reaction inside the furnace, significantly simplifies the furnace structure, and improves the operational reliability of the low-rank coal pyrolysis furnace.

Description

Technical Field

[0001] This invention relates to the field of low-rank coal pyrolysis technology, and in particular to a connection structure between the medium-temperature dry distillation section and the high-temperature dry distillation section of a low-rank coal pyrolysis furnace. Background Technology

[0002] Externally heated pyrolysis furnaces typically consist of multiple functional sections arranged sequentially from top to bottom, such as a drying section, a low-temperature retorting section, a medium-temperature retorting section, a high-temperature retorting section, and a cooling section. The connection between the medium-temperature and high-temperature retorting sections is a critical part of the furnace structure. In traditional designs, water-sealed connections or other flexible connection structures are often used to address the difference in thermal expansion and contraction between the high-temperature and medium-temperature retorting sections. A typical water-sealed connection involves placing a water seal groove between the two sections, forming an airtight barrier with the water seal fluid, while allowing relative displacement between the two sections. However, this water-sealed connection method has the following drawbacks: 1) The water seal medium will continuously vaporize under high temperature conditions. Once the water vapor enters the high temperature carbonization chamber, it is easy to trigger a water-gas reaction, resulting in coking on the inner wall of the furnace and abnormal product gas composition.

[0003] 2) The water seal structure requires continuous water supply and cooling, which increases the system's water consumption and the complexity of operation and maintenance, and has poor adaptability in water-scarce or cold regions.

[0004] 3) The water seal trough complicates the furnace structure, not only taking up space, but also potentially causing seal failure due to deposits or temperature fluctuations, posing a risk of air leakage.

[0005] 4) The temperature of the high-temperature distillation section can reach 700-1000℃ or even higher, while the temperature of the medium-temperature distillation section is much lower than that of the high-temperature distillation section, resulting in a significant difference in thermal expansion between the two metal structures. If a rigid connection is used, thermal stress will accumulate at the interface; while water-sealed connections have a certain degree of flexibility, they cannot completely eliminate thermal expansion stress, and at the same time reduce the structural strength and stability.

[0006] Currently, some pyrolysis furnaces adopt a modular design, which means that the carbonization furnace is manufactured and assembled in sections. This type of modular pyrolysis furnace still uses the traditional inter-section connection structure (such as water seal connection or expansion joint), and has not proposed solutions for the thermal stress and sealing problems at the connection between the medium-temperature carbonization section and the high-temperature carbonization section. Summary of the Invention

[0007] This invention provides a connection structure between the medium-temperature and high-temperature dry distillation sections of a low-rank coal pyrolysis furnace. The medium-temperature and high-temperature dry distillation sections are connected by a rigid connection structure, employing a special thermal compensation and sealing mechanism to effectively compensate for thermal expansion and contraction and ensure good sealing performance at the connection. Compared with the existing water-sealed connection structure, this invention fundamentally eliminates the adverse effects of water vapor on the pyrolysis reaction inside the furnace, significantly simplifies the furnace structure, and improves the operational reliability of the low-rank coal pyrolysis furnace.

[0008] To achieve the above objectives, the present invention employs the following technical solution: A connection structure between a medium-temperature carbonization section and a high-temperature carbonization section of a low-rank coal pyrolysis furnace is disclosed. Both the medium-temperature and high-temperature carbonization sections have refractory linings. A medium-temperature section furnace protection plate is installed around the furnace body of the medium-temperature carbonization section, and a high-temperature section furnace protection plate is installed around the furnace body of the high-temperature carbonization section. The medium-temperature section furnace protection plate and the high-temperature section furnace protection plate are fixedly connected. A heat insulation component is installed between the medium-temperature section furnace protection plate at the bottom of the medium-temperature carbonization section and the refractory lining. The heat insulation component consists of at least two layers of ceramic fiber boards and a nanoporous heat insulation plate sandwiched between two adjacent layers of ceramic fiber boards. An expansion joint is provided between the furnace wall of the high-temperature carbonization section and the furnace wall of the medium-temperature carbonization section, and the expansion joint is filled with flexible, high-temperature resistant sealing material.

[0009] The medium-temperature section furnace protection plate and the high-temperature section furnace protection plate are fixedly connected by welding or bolts.

[0010] When the medium-temperature section furnace guard plate and the high-temperature section furnace guard plate are fixed by welding, the weld is continuous along the circumference of the furnace body, and the outside of the weld is coated with high-temperature resistant sealant or fitted with a metal band.

[0011] The heat insulation component is fixed to the furnace guard plate of the medium temperature section by high-temperature resistant adhesive and metal anchors.

[0012] The ceramic fiber board is a high-alumina fiber rigid board with a single-layer thickness of 10-30 mm; the nanoporous heat insulation board is made of aerogel material or microporous calcium silicate material with a single-layer thickness of 5-15 mm.

[0013] The bottom of the insulation component is sealed with a ceramic fiber blanket or heat-resistant sealant.

[0014] The furnace size of the high-temperature carbonization section is larger than that of the medium-temperature carbonization section, and the connection between the medium-temperature and high-temperature carbonization sections has a stepped structure; the top of the furnace guard plate of the high-temperature section extends horizontally inward and connects with the furnace guard plate of the medium-temperature section; a guide ring is provided at the stepped structure of the high-temperature carbonization section, the guide ring is formed of refractory castable, and the inner surface is an inward and downward inclined surface; an annular expansion joint is left between the top surface of the guide ring and the horizontal furnace guard plate of the high-temperature section, and the expansion joint is filled with flexible high-temperature resistant sealing filler.

[0015] The flexible high-temperature resistant sealing filler is a ceramic fiber rope.

[0016] The carbonization chamber of the high-temperature carbonization section and the carbonization chamber of the medium-temperature carbonization section are connected by a U-shaped gas guide pipe. The U-shaped gas guide pipe is located outside the low-rank coal pyrolysis furnace. A gas flow regulating valve is installed on the U-shaped gas guide pipe near the high-temperature carbonization section. A corrugated expansion joint is installed on the vertical section of the U-shaped gas guide pipe.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1) Eliminates the drawbacks of water seals: No water seal medium is required, eliminating adverse reactions caused by water vapor entering the furnace, reducing system water consumption and maintenance requirements.

[0018] 2) Significantly reduced thermal stress: The insulation components keep the outer wall of the interface at a low temperature, reduce the difference in thermal expansion, avoid stress concentration and cracking risk at the welded interface, and extend the furnace life.

[0019] 3) Reliable sealing: The welded hard connection combined with high-temperature resistant sealing material ensures excellent airtightness at the interface, eliminating the risk of leakage and improving the safety and efficiency of the pyrolysis process.

[0020] 4) Simple structure: The cumbersome water seal tank and auxiliary equipment are eliminated, the structural design is more compact, and manufacturing and installation are convenient. At the same time, the drainage and water replenishment systems required due to the existence of water seal are avoided, reducing investment and operating costs.

[0021] 5) Outstanding innovation: This invention limits the scope of protection to the coupling structure and thermal field control of the medium-temperature section and the high-temperature section, which is different from the existing technology that focuses on modularization of the whole furnace. It has clear innovativeness and engineering practical value. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the connection structure between the medium-temperature dry distillation section and the high-temperature dry distillation section described in this invention.

[0023] Figure 2 yes Figure 1 Enlarged view of Part I.

[0024] Figure 3 yes Figure 1 DD section view in the image.

[0025] In the diagram: 1-Medium-temperature dry distillation section; 11-Medium-temperature section furnace protection plate; 2-High-temperature dry distillation section; 21-High-temperature section furnace protection plate; 3-Ceramic fiber board; 4-Nano-microporous heat insulation board; 5-Weld seam; 6-Ceramic fiber rope; 7-U-shaped gas guide pipe; 71-Corrugated expansion joint; 72-Gas flow regulating valve. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1 , Figure 2As shown, the present invention discloses a connection structure between the intermediate-temperature and high-temperature carbonization sections of a low-rank coal pyrolysis furnace. Both the intermediate-temperature carbonization section 1 and the high-temperature carbonization section 2 have refractory linings. An intermediate-temperature section furnace guard plate 11 is installed around the furnace body of the intermediate-temperature carbonization section 1, and a high-temperature section furnace guard plate 21 is installed around the furnace body of the high-temperature carbonization section 2. The intermediate-temperature section furnace guard plate 11 and the high-temperature section furnace guard plate 21 are fixedly connected. A heat insulation component is installed between the intermediate-temperature section furnace guard plate 11 at the lower part of the intermediate-temperature carbonization section 1 and the refractory lining. The heat insulation component consists of at least two layers of ceramic fiber boards 3 and a nanoporous heat insulation plate 4 sandwiched between two adjacent layers of ceramic fiber boards 3. This component reduces heat conduction from the high-temperature carbonization section 2 to the intermediate-temperature section furnace guard plate 11, keeping the temperature of the intermediate-temperature section furnace guard plate 11 at the connection points below 80°C. Based on this, a rigid connection can be used between the two furnace guard plates without generating significant thermal stress, forming a reliable seal. An expansion joint is provided between the furnace wall of the high-temperature dry distillation section 2 and the furnace wall of the medium-temperature dry distillation section 1 to compensate for the thermal expansion of the refractory linings of the two sections. The expansion joint is filled with flexible high-temperature resistant sealing filler to prevent gas leakage at the connection.

[0027] Preferably, the intermediate-temperature section furnace guard plate 11 and the high-temperature section furnace guard plate 21 are fixedly connected by welding or bolting. When using bolting, sealing is achieved by adding a gasket or filling with sealant.

[0028] Preferably, when the medium-temperature section furnace guard plate 11 and the high-temperature section furnace guard plate 21 are fixed by welding, the weld seam is continuous along the circumference of the furnace body, and the outside of the weld seam 5 is coated with high-temperature resistant sealant or fitted with a metal band to further improve airtightness and connection stability.

[0029] The heat insulation component is fixed to the medium-temperature section furnace plate 11 by high-temperature resistant adhesive and metal anchors.

[0030] The ceramic fiber board 3 is a high-alumina fiber rigid board with a single-layer thickness of 10-30 mm; the nanoporous heat insulation board 4 is made of aerogel material or microporous calcium silicate material with a single-layer thickness of 5-15 mm.

[0031] The bottom of the thermal insulation component is sealed with a ceramic fiber blanket or heat-resistant sealant, forming a double sealing barrier with the sealing structure on the outside of weld 5.

[0032] The furnace size of the high-temperature carbonization section 2 is larger than that of the medium-temperature carbonization section 1. The connection between the medium-temperature carbonization section 1 and the high-temperature carbonization section 2 has a stepped structure. The top of the high-temperature section furnace guard plate 21 extends horizontally inward and connects with the medium-temperature section furnace guard plate 11. The high-temperature carbonization section 2 is provided with a guide ring at the stepped structure. The guide ring is formed by refractory castable and the inner surface is an inclined surface that slopes inward and downward. An annular expansion joint (preferably with a height of 5-10 mm) is left between the top surface of the guide ring and the horizontal high-temperature section furnace guard plate 21. The expansion joint is filled with flexible high-temperature resistant sealing filler.

[0033] The flexible high-temperature resistant sealing filler is ceramic fiber rope 6.

[0034] like Figure 3 As shown, the carbonization chamber of the high-temperature carbonization section 2 and the carbonization chamber of the medium-temperature carbonization section 1 are connected by a U-shaped gas guide pipe 7. The U-shaped gas guide pipe 7 is located outside the low-rank coal pyrolysis furnace. A gas flow regulating valve 72 is installed on the U-shaped gas guide pipe 7 near the high-temperature carbonization section 2, and a corrugated expansion joint 71 is installed on the vertical section of the U-shaped gas guide pipe 7. The gas flow regulating valve 72 is used to control the flow rate of flue gas entering the carbonization chamber of the medium-temperature carbonization section 1, thereby regulating the temperature inside the carbonization chamber of the medium-temperature carbonization section 1. The corrugated expansion joint 71 is used to absorb the vertical thermal expansion displacement of the high-temperature carbonization section 2 relative to the medium-temperature carbonization section 1.

[0035] In the connection structure between the intermediate-temperature and high-temperature carbonization sections of a low-rank coal pyrolysis furnace described in this invention, the rigid connection between the intermediate-temperature carbonization section 1 and the high-temperature carbonization section 2 is formed by circumferential welding or bolting between the intermediate-temperature section furnace guard plate 11 (i.e., the outer shell of the intermediate-temperature carbonization section 1 furnace body) and the high-temperature section furnace guard plate 21 (i.e., the outer shell of the high-temperature carbonization section 2 furnace body). A thermal expansion compensation and insulation structure, i.e., an insulation component, is provided at the connection point between the two sections. Specifically, it includes: multi-layer ceramic fiber boards 3 disposed on the inner side of the intermediate-temperature section furnace guard plate 11, and nanoporous insulation boards 4 sandwiched between adjacent layers of ceramic fiber boards 3. The insulation component can greatly reduce the heat conduction from the carbonization chamber of the high-temperature carbonization section 2 to the intermediate-temperature section furnace guard plate 11, keeping the temperature of the intermediate-temperature section furnace guard plate 11 near the connection point below 80°C. Therefore, the intermediate-temperature section furnace guard plate 11 and the high-temperature section furnace guard plate 21 will not experience additional thermal expansion, and stress concentration is eliminated. This is the basis for achieving a firm coupling between the two steel structures using rigid connection methods such as welding. Meanwhile, the thermal insulation components have a certain degree of compressive elasticity, which can absorb the small relative displacement between the two steel structures and achieve thermal expansion compensation.

[0036] To ensure airtightness at the joints, this invention employs a design combining circumferential continuous welding with a high-temperature heat-insulating sealing structure. In addition to the airtightness of the continuous weld seam, the inner side of the joint is filled with a high-temperature resistant sealing material (such as ceramic fiber blanket or heat-resistant sealing putty) to seal any potential micro-gaps, preventing leakage of raw coal gas from the furnace and the intrusion of external oxygen. Compared to water-sealed connections, this invention eliminates the problem of water vapor entering the furnace, thus avoiding water-gas side reactions and coking, ensuring the stability of the pyrolysis reaction and the cleanliness of the furnace walls.

[0037] 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.

[0038] Example: like Figure 1 , Figure 2 As shown, in this embodiment, the externally heated vertical pyrolysis furnace for low-rank coal pyrolysis includes a medium-temperature dry distillation section 1 and a high-temperature dry distillation section 2. In the original design, the medium-temperature dry distillation section 1 and the high-temperature dry distillation section 2 were connected by a water seal tank. In this embodiment, the water seal connection structure is changed to a rigid connection structure. The specific implementation process is as follows: The intermediate-temperature section furnace guard plate 11 and the high-temperature section furnace guard plate 21 are directly butt-welded together using a full-circumference weld. Before welding, a heat insulation component is attached to the inner side of the intermediate-temperature section furnace guard plate 11 near the interface. The heat insulation component consists of two annular ceramic fiber boards 3 sandwiching an annular nanoporous heat insulation board 4. The ceramic fiber board 3 is made of high-alumina ceramic fiber rigid board, with a single layer thickness of 20mm, a temperature resistance of up to 1260℃, and a thermal conductivity of less than 0.1 W / m·K. The nanoporous heat insulation board 4 is 10mm thick, made of aerogel material, and has a thermal conductivity of less than 0.06 W / m·K. After the three layers of boards are tightly stacked, they are fixed to the inner side of the intermediate-temperature section furnace guard plate 11 with high-temperature resistant adhesive and anchor nails, making them less prone to falling off. After assembly, the total thickness of the sandwich-structured heat insulation component is 50mm.

[0039] The high-temperature carbonization section 2 is lined with refractory bricks. At the interface between the top of the refractory brick lining and the medium-temperature carbonization section 1, an 8mm high annular expansion joint is left. This expansion joint is filled with compressible ceramic fiber rope 6, which serves two purposes: first, as a filler for construction joints during furnace loading to prevent leakage of raw gas at the masonry joints; second, to accommodate the thermal expansion of the refractory lining during normal production, preventing stress transfer to the medium-temperature section furnace lining plate 11. This design ensures that the refractory lining of the high-temperature carbonization section can expand and contract freely at the junction of the two sections, while the medium-temperature section furnace lining plate 11 and the high-temperature section furnace lining plate 21 are essentially free from thermal deformation due to the presence of the insulation components. Therefore, the weld 5 is located in the low-temperature zone (<80℃) and will not crack due to high-temperature stress.

[0040] After the two furnace lining plates are welded together, the interface area between the medium-temperature carbonization section 1 and the high-temperature carbonization section 2 is completely sealed. To further improve the airtightness of the connection, a layer of high-temperature resistant sealant is applied to the outside of the weld 5. On the inside of the medium-temperature section furnace lining plate 11, since the insulation components are fully fitted without gaps, a layer of heat-resistant sealant is applied only to the bottom edge of the insulation components near the interface, ensuring airtight contact with the top surface of the refractory brick lining of the high-temperature carbonization section 2. After taking the above sealing measures, the high-temperature raw coal gas in the furnace is strictly sealed and will not leak out at the connection.

[0041] In this embodiment, a U-shaped gas guide pipe 7 located outside the furnace is used to introduce the high-temperature flue gas generated in the carbonization chamber of the high-temperature dry distillation section 2 into the medium-temperature dry distillation section 1 to achieve waste heat utilization. For example... Figure 3 As shown, a flue gas outlet is opened on the side wall of the high-temperature distillation section 2, connecting to the lower end of the U-shaped gas guide pipe 7. After being discharged through the U-shaped gas guide pipe 7, the high-temperature flue gas bends upward and enters the medium-temperature distillation section 1. A stainless steel corrugated expansion joint 71 is provided in the middle of the U-shaped gas guide pipe 7 to compensate for the vertical thermal expansion that may occur between the high-temperature distillation section 2 and the medium-temperature distillation section 1. At the same time, a gas flow regulating valve 72 is installed at the lower part of the vertical section of the U-shaped gas guide pipe 7 to control the amount of flue gas entering the carbonization chamber of the medium-temperature distillation section 1 and prevent overheating inside the medium-temperature distillation section 1. Through the above design, the difference in thermal expansion and contraction between the high-temperature distillation section 2 and the medium-temperature distillation section 1 after rigid connection is further buffered, which greatly improves the thermal stability of the entire connection structure.

[0042] Actual verification showed that when the inner wall temperature of the high-temperature distillation section 2 reached 800–900°C, the outer wall temperature of the furnace guard plate 11 in the medium-temperature section was controlled at around 75°C, completely below the target value of 80°C. The expansion stress of the weld 5 at the interface was close to zero, and no cracks or leaks were observed during furnace start-up, shutdown, and temperature fluctuations. After several months of continuous operation, no coking or ash accumulation was observed on the wall surface at the connection between the medium-temperature distillation section 1 and the high-temperature distillation section 2, and no abnormal wear was found during internal maintenance, proving the reliability and superiority of the design of this invention.

[0043] In summary, the connection structure between the medium-temperature and high-temperature dry distillation sections of the low-rank coal pyrolysis furnace described in this invention effectively solves the sealing and thermal compensation problems at the connection point between the two sections, and is particularly suitable for the design and modification of multi-section vertical furnaces such as externally heated low-rank coal dry distillation furnaces.

[0044] 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 low-rank coal pyrolysis furnace, comprising a medium-temperature carbonization section and a high-temperature carbonization section, wherein the furnace body of both the medium-temperature and high-temperature carbonization sections is lined with refractory material; characterized in that, The furnace body of the medium-temperature carbonization section is surrounded by a medium-temperature section protective plate, and the furnace body of the high-temperature carbonization section is surrounded by a high-temperature section protective plate. The medium-temperature section protective plate and the high-temperature section protective plate are fixed by welding, with a continuous weld along the circumference of the furnace body. The outside of the weld is coated with high-temperature resistant sealant or fitted with metal bands. A heat insulation component is installed between the medium-temperature section protective plate and the refractory lining at the bottom of the medium-temperature carbonization section. The heat insulation component is fixed to the medium-temperature section protective plate by high-temperature resistant adhesive and metal anchors. The heat insulation component consists of at least two layers of ceramic fiber boards and a nanoporous heat insulation board sandwiched between two adjacent layers of ceramic fiber boards. The furnace chamber size of the high-temperature carbonization section is larger than that of the medium-temperature carbonization section. The medium-temperature carbonization section and the high-temperature carbonization section... The connection has a stepped structure; the top of the high-temperature section furnace lining plate extends horizontally inward and connects with the medium-temperature section furnace lining plate; the high-temperature carbonization section has a guide ring at the stepped structure, which is formed by refractory castable and has an inner surface that slopes inward and downward; an annular expansion joint is left between the top surface of the guide ring and the horizontal high-temperature section furnace lining plate, and the expansion joint is filled with flexible high-temperature resistant sealing filler, which is ceramic fiber rope; the carbonization chamber of the high-temperature carbonization section and the carbonization chamber of the medium-temperature carbonization section are connected by a U-shaped gas guide pipe, which is located outside the low-rank coal pyrolysis furnace, and a gas flow regulating valve is installed on the U-shaped gas guide pipe near the high-temperature carbonization section, and a corrugated expansion joint is installed on the vertical section of the U-shaped gas guide pipe.

2. The low-rank coal pyrolysis furnace according to claim 1, characterized in that, The ceramic fiber board is a high-alumina fiber rigid board with a single-layer thickness of 10-30 mm; the nanoporous heat insulation board is made of aerogel material or microporous calcium silicate material with a single-layer thickness of 5-15 mm.

3. A low-rank coal pyrolysis furnace according to claim 1, characterized in that, The bottom of the insulation component is sealed with a ceramic fiber blanket or heat-resistant sealant.

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