Installation method for heat preservation and heat tracing pipeline

Abstract

The invention discloses a heat-preservation heat tracing pipeline installation method. The invention belongs to the technical field of pipeline heat preservation and heat tracing, and particularly relates to a heat preservation and heat tracing structure mounting method for a high-temperature pipeline of a sulfur recovery device, which comprises the following steps of: pretreating the surface of the pipeline, welding a supporting piece group, mounting a heat tracing system, coating a galvanized welded wire mesh, mounting a heat preservation layer, and finally assembling an outer protective layer. A unique'heating space 'is formed according to the steps, so that the inner wall of the thermal insulation layer is separated from the high-temperature process pipeline and the outer wall of the heat tracing pipe by a relatively static air layer, the heat loss is effectively reduced, and the heat tracing efficiency is improved; and natural convection of air in the heating space can also enable the circumferential temperature of the pipeline to be more uniform, so that the energy-saving effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of pipeline insulation and heat tracing technology, specifically relating to the installation method of insulation and heat tracing structure for high-temperature pipelines in sulfur recovery devices. Background Technology

[0002] The sulfur recovery unit is equipped with some process gas pipelines and tail gas pipelines, which can be used as switching channels between different treatment series and as discharge channels during unit start-up and shutdown. The internal medium has no continuous flow characteristics. Because sulfur vapor may remain in the pipeline, even without medium flow, the pipe wall temperature must be maintained above the freezing point of elemental sulfur (usually not lower than 120°C) to prevent sulfur vapor from condensing, solidifying, and accumulating, causing pipeline blockage, internal wall corrosion, and difficulties in unit start-up, thus ensuring the long-term stable operation of the pipeline.

[0003] In existing technologies such as jacketed heat tracing, internal heat tracing, or conventional external heat tracing, the heat tracing pipe is typically laid tightly against the outer wall of the process pipeline and wrapped with an insulation layer. In this method, heat easily dissipates through the insulation material, resulting in significant heat loss and low efficiency. Furthermore, the heat transfer between the heat tracing pipe and the process pipeline relies on contact conduction, and the effectiveness is significantly affected by the tightness of the contact, easily leading to uneven circumferential temperature distribution in the pipeline and failing to ensure that the overall temperature meets the requirements for sulfur solidification prevention. To maintain the pipe wall temperature, it is necessary to increase the parameters of the heat tracing steam or enlarge the specifications of the heat tracing pipe, resulting in high energy consumption. Therefore, improving installation methods is particularly important for pipeline insulation and heat tracing structures that reduce heat loss, improve heat tracing efficiency, ensure uniform circumferential temperature of the pipeline, and achieve energy savings. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for installing heat-insulated and heat-tracing pipelines to reduce heat loss, improve heat tracing efficiency, make the circumferential temperature of the pipeline uniform, and improve energy-saving effect.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a method for installing insulated heat tracing pipes, characterized by including the following steps: Step 1: Clean the outer surface of the process piping; Step 2, Welding of the support assembly: Angle steels are arranged along the axial and circumferential directions of the process pipeline, and fixed to the process pipeline by double-sided fillet welding. Circumferential flat steels are welded to the top of the angle steels arranged circumferentially on the same cross section. The angle steels and circumferential flat steels together form a ring support frame. Step 3, Heat Tracing System Installation: The heat tracing pipe is arranged circumferentially along the outer wall of the process pipeline and temporarily fixed with fasteners. When fixing, ensure the gap between the heat tracing pipe and the outer wall of the process pipeline. The heat tracing pipe is located inside the support frame. Step 4, Welded Wire Mesh Installation: A layer of galvanized welded wire mesh is tied to the outside of the circumferential flat steel of the support component; Step 5, Insulation layer installation: The outer side of the welded wire mesh is wrapped in layers of composite aluminum silicate products and installed with staggered joints to form an insulation layer. Step 6: Install the outer protective layer; Furthermore, in step two, the angle steel is spaced 1 meter apart along the axial direction of the process pipeline, and the circumferential arrangement angle is 30°; Furthermore, in step two, the angle steel (3) has the following specifications: ∠50×32×3 (long side width 50mm, short side width 32mm, angle steel thickness 3mm); Furthermore, in step two, the circumferential flat steel is made of Q235 material and has a thickness of 3mm; Furthermore, in step three, the heat tracing pipe is a steam tracing pipe; Furthermore, in step three, when the heat tracing pipe is arranged along the process pipeline, the circumferential arrangement angle is 90° or 120°, and the gap distance between it and the outer wall is maintained at 15-20mm. Furthermore, in step three, the fasteners are stainless steel pipe clamps or high-temperature resistant cable ties, and the spacing between the fasteners is no more than 600mm. Furthermore, in step four, the galvanized welded wire mesh has a mesh size of 1.2mm, and is tied with 20# galvanized iron wire at 200mm intervals, with double-layer wrapping at the corners; Furthermore, in step five, the thickness of each insulation layer is controlled at 40-50mm, and the joints are sealed with high-temperature adhesive. Furthermore, in step six, the outer protective layer is a 0.8mm thick 3003 aluminum alloy sheet, installed using a snap-fit ​​connection method, with an overlap length of not less than 50mm.

[0006] Compared with existing technologies, the installation method of this invention uses components such as angle steel, flat steel, and galvanized welded wire mesh to form a stable support frame structure, creating a unique "heating space". This separates the inner wall of the insulation layer from the outer wall of the high-temperature process pipeline and the heat tracing pipe with a relatively static air layer, effectively reducing heat loss and improving heat tracing efficiency. The natural convection of air in the heating space also makes the circumferential temperature of the pipeline more uniform, improving energy-saving effect. Attached Figure Description

[0007] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0008] Figure 1 This is an axial cross-sectional schematic diagram of the heat-insulating and heat-tracing pipe structure of the present invention.

[0009] Figure 2This is a schematic diagram of the circumferential cross-section of the heat-insulating and heat-tracing pipe structure of the present invention.

[0010] In the diagram, 1-process piping; 2-steam tracing pipe; 3-supporting angle steel; 4-circumferential flat steel; 5-galvanized welded wire mesh; 6-insulation layer; 7-outer protective layer; 8-heating space. Detailed Implementation

[0011] To enable those skilled in the art to better understand the present invention, the present invention will be further described clearly and completely below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0012] The basic concept of this embodiment is to provide a method for installing insulated and heat-tracing pipelines for sulfur recovery devices, including the following steps.

[0013] Step 1: Pre-treatment of the outer surface of process piping 1.

[0014] The sandblasting process is adopted, using quartz sand that meets the standard requirements as the sandblasting medium. The sandblasting equipment is moved at a uniform speed to perform all-round sandblasting treatment on the outer wall of the pipeline, removing the oxide scale, rust products, oil stains, dust and other debris attached to the outer wall of the pipeline. After the sandblasting is completed, the surface quality of the outer wall of the pipeline must reach the Sa2.5 level rust removal standard, that is, there is no visible oxide scale, rust and oil stains on the surface of the pipeline.

[0015] After the rust removal is completed and deemed satisfactory, the outer wall of the pipeline is purged with dry compressed air at a pressure of not less than 0.6 MPa to ensure that any residual sandblasting dust and fine impurities on the pipeline surface are thoroughly removed. After purging, the surface roughness of the pipeline outer wall is tested using a surface roughness meter to ensure that the surface roughness Ra is controlled within the range of 50-80 μm. This roughness range can effectively increase the bonding strength between the pipeline outer wall and subsequent welded joints, while providing good contact conditions for heat transfer in the heat tracing system, and avoiding a decrease in heat transfer efficiency due to a smooth surface or the presence of impurities.

[0016] Step 2: Welding and installation of the support assembly.

[0017] Along the axial direction of process pipeline 1, a support assembly is evenly installed at 1-meter intervals, with a spacing deviation of no more than ±50mm, ensuring uniform support for subsequent structural layers. At the installation section of each support assembly, along the circumferential direction of the pipeline, an angle steel 3 of model ∠50×32×3 (long side width 50mm, short side width 32mm, angle steel thickness 3mm) is welded at 30° intervals, with a total of 12 angle steel 3 welded at each installation section. The angle steel 3 is made of Q235B carbon structural steel to ensure sufficient load-bearing strength and weldability.

[0018] One leg of angle steel 3 is connected to the outer wall of process pipe 1 by double-sided fillet weld. J422 type low-carbon steel welding rods with a diameter of 3.2mm are used for welding. The weld leg height is not less than 3mm and is uniform, free from welding defects such as slag inclusions, porosity, and cracks. A segmented back-welding method is used during welding, with each segment length controlled at 50-80mm and an interval of 3-5 minutes between segments. This welding method effectively controls thermal deformation during welding, ensuring that the radial height error of all angle steels 3 in each support assembly is controlled within ±2mm, thus guaranteeing the overall flatness of the support assembly.

[0019] On the outer side of the top of all angle steels 3 with the same diameter, weld a ring of circumferential flat steel 4 with a thickness of 3mm and material of Q235B. The width of the circumferential flat steel 4 is 50mm. Welding is done using continuous fillet welding, and the weld leg height is not less than 3mm. After welding, the circumferential flat steel 4 forms a complete ring support frame. The diameter error of the frame does not exceed 5mm to ensure the roundness and stability of the frame. After all welding operations are completed, 100% penetrant testing (PT testing) is performed on all weld joints to ensure that there are no defects such as surface cracks or incomplete penetration.

[0020] Step 3: Installation of the heat tracing system.

[0021] Multiple seamless steel pipes with a specification of DN20 are selected as steam tracing pipes 2. The material of steam tracing pipes 2 is 20# high-quality carbon structural steel, whose high temperature resistance and corrosion resistance meet the requirements of the process medium. The heat load of a single tracing pipe 2 does not exceed 250W / m. The specific number and arrangement angle of tracing pipes 2 need to be determined according to the actual heat load calculation results of process pipeline 1. Usually, they are arranged at equal angles along the circumference of the outer wall of process pipeline 1. One tracing pipe 2 can be arranged every 120° (3 tracing pipes) or one tracing pipe 2 can be arranged every 90° (4 tracing pipes) to ensure that the heat generated by the tracing pipes 2 can be evenly transferred to the entire outer wall of process pipeline 1.

[0022] During installation, heat tracing pipe 2 should be temporarily fixed to the outer wall of angle steel 3 or process pipeline 1 using 304 stainless steel pipe clamps or high-temperature resistant cable ties. The spacing between the pipe clamps or cable ties should not exceed 600mm, and the fixing points should be evenly distributed to prevent the heat tracing pipe 2 from loosening or shifting. During the fixing process, the distance between the heat tracing pipe 2 and the outer wall of process pipeline 1 must be strictly controlled and maintained within the range of 15-20mm. This distance can form a reasonable air heat exchange layer, improve heat transfer efficiency, and at the same time avoid local overheating or uneven heat transfer caused by direct contact between the heat tracing pipe 2 and the outer wall of the pipeline.

[0023] All heat tracing pipes 2 must be located within the radial space enclosed by angle steel 3, and a safe distance of not less than 5mm must be maintained between the heat tracing pipes 2 and the inner wall of the supporting frame (circumferential flat steel 4).

[0024] Step 4: Installation of galvanized welded wire mesh A galvanized welded wire mesh 5 with an aperture of 1.2mm and a wire diameter of 1.0mm is selected. The material of the welded wire mesh 5 is 20# galvanized iron wire, which has good corrosion resistance and mechanical strength, and can effectively resist the high temperature environment in the heating space and the erosion of the external environment. The galvanized welded wire mesh 5 is completely wrapped around the outside of the support assembly, ensuring that the welded wire mesh 5 is not loose or wrinkled during the wrapping process. The welded wire mesh 5 is tied and fixed with 20# galvanized iron wire. The binding points are evenly distributed along the outside of the circumferential flat steel 4, and the binding spacing is not greater than 200mm. Each binding point is wrapped with double-strand iron wire for no less than 3 turns to ensure a firm binding and prevent the welded wire mesh 5 from falling off.

[0025] The overlap width of welded wire mesh 5 shall not be less than 50mm, and the overlap shall be fixed with iron wire to ensure that there are no gaps at the overlap. In special parts such as pipe corners, bends and joints, double-layer galvanized welded wire mesh shall be used for wrapping. The overlap width of the double-layer welded wire mesh shall not be less than 100mm to enhance the structural strength and sealing of special parts.

[0026] Step 5: Install insulation layer 6.

[0027] Composite aluminum silicate insulation products with a density ≥128kg / m³ are selected, as these products possess excellent thermal insulation performance and chemical stability. The insulation layer is constructed using a layered, staggered installation method, with each layer's thickness controlled at 40-50mm. The specific number of layers is determined based on the design insulation requirements of process piping 1, ensuring the total insulation thickness meets heat loss control standards.

[0028] When installing in layers, the joints of adjacent insulation layers must be staggered, with a stagger distance of no less than 100mm between layers. There should be no continuous seams at the joints to prevent heat loss. The joints of the insulation layers should be sealed with a high-temperature adhesive. The adhesive should be applied evenly and fully to ensure a tight seal without gaps, air bubbles, or other defects.

[0029] Step Six: Installation of the Outer Protective Layer A 0.8mm thick 3003 aluminum alloy sheet is selected as the outer protective layer 7. The outer protective layer 7 is installed using a seam connection method with a seam width of not less than 15mm. The seam is tightly fitted without any looseness or gaps. The overlap length between two adjacent aluminum alloy sheets is not less than 50mm. At the expansion joint of the process pipeline 1, the outer protective layer 7 needs to be equipped with a flexible compensation structure to ensure that the outer protective layer 7 will not be torn or damaged during the thermal expansion and contraction of the pipeline, thus ensuring the sealing and integrity of the outer protective layer.

[0030] After the outer protective layer is installed, its surface is cleaned and inspected to ensure that there are no scratches, deformations, rusts or other defects, and that the connections are firm and reliable. At this point, the construction of the entire process pipeline heat tracing and insulation system is complete.

[0031] Through the above structure, the heat generated by the heat tracing pipe 2 is effectively confined within the heating space 8, allowing for uniform and efficient heating of the process pipeline 1 via natural convection and radiation heat exchange, achieving a thermal efficiency of over 92%. Simultaneously, the air layer's insulation effect keeps the outer surface temperature of the insulation layer 6 below 50℃, significantly reducing the heat flux density through the insulation layer 6 (≤20W / m²), thus achieving excellent insulation and heat tracing effects. Actual measurements show that the pipeline can maintain a medium temperature above 180℃ for over 72 hours during shutdown, making it particularly suitable for intermittently used pipelines in sulfur recovery units that require long-term high-temperature maintenance.

[0032] The scope of protection claimed by this invention is not limited to the specific embodiments described above. For those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for installing insulated heat tracing pipes, characterized in that: Includes the following steps: Step 1, cleaning the outer surface of the process piping (1); Step 2, Welding of the support assembly: Angle steel (3) is arranged along the axial and circumferential directions of the process pipeline (1) respectively, and is fixed to the process pipeline (1) by double-sided fillet welding. Circumferential flat steel (4) is welded to the top of the angle steel (3) arranged in the same cross section. The angle steel (3) and the circumferential flat steel (4) together form a ring support frame. Step 3, Heat Tracing System Installation: The heat tracing pipe (2) is arranged circumferentially along the outer wall of the process pipeline (1) and temporarily fixed with fasteners. When fixing, ensure the gap between the heat tracing pipe (2) and the outer wall of the process pipeline (1). The heat tracing pipe (2) is located inside the support frame. Step 4, Installation of welded wire mesh (5): A layer of galvanized welded wire mesh (5) is tied to the outside of the circumferential flat steel (4) of the support member; Step 5, Installation of insulation layer (6): The outer side of the welded wire mesh is wrapped in layers with composite aluminum silicate products and installed in a staggered manner to form an insulation layer (6). Step 6, Install the outer protective layer (7).

2. The method according to claim 1, characterized in that: In step two, the angle steel (3) is spaced 1 meter apart along the axial direction of the process pipeline (1), and the circumferential arrangement angle is 30°.

3. The method according to claim 1 or 2, characterized in that: In step two, the angle steel (3) has the following specifications: ∠50×32×3 (long side width 50mm, short side width 32mm, angle steel thickness 3mm).

4. The method according to claim 3, characterized in that: In step two, the circumferential flat steel (4) is made of Q235 material and has a thickness of 3mm.

5. The method according to claim 1, characterized in that: In step three, the heat tracing pipe (2) is a steam tracing pipe.

6. The method according to claim 5, characterized in that: In step three, when the heat tracing pipe (2) is arranged along the process pipeline (1), the circumferential arrangement angle is 90° or 120°, and the gap distance between it and the outer wall is maintained at 15-20mm.

7. The method according to claim 6, characterized in that: In step three, the fasteners are stainless steel pipe clamps or high-temperature resistant cable ties, and the spacing between the fasteners is no more than 600mm.

8. The method according to claim 1, characterized in that: In step four, the galvanized welded wire mesh (5) has a mesh size of 1.2mm and is tied with 20# galvanized iron wire at 200mm intervals. The corners are double-wrapped.

9. The method according to claim 1, characterized in that: In step five, the thickness of each insulation layer (6) is controlled at 40-50mm, and the joints are sealed with high-temperature adhesive.

10. The method according to claim 9, characterized in that: In step six, the outer protective layer (7) is a 0.8mm thick 3003 aluminum alloy sheet, which is installed using a snap-fit ​​connection method.

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