Multi-stage series-parallel anti-coking organic heat carrier furnace

Abstract

The present application relates to a kind of multi-section series-parallel anti-coking organic heat carrier furnace, including furnace body and the burner at the bottom in the furnace body, the furnace body is divided into at least two sections from top to bottom, each section is arranged coil group, each coil group includes inner circle coil and outer circle coil, the coil group in each section is in series and / or parallel connection.The present application can avoid the temperature difference of heat transfer medium in coil too large, and further prevent coking.

Description

Technical Field

[0001] This invention relates to the field of organic heat carrier furnaces, and more specifically to a multi-segment series-parallel anti-coking organic heat carrier furnace. Background Technology

[0002] Current organic heat carrier furnaces generally consist of inner and outer coils. The inner coils are connected in series, and the outer coils are also connected in series. Then, the inner and outer coils are connected in large series or parallel connections. Because the inner coils run through the entire radiative heat exchange area of ​​the furnace, they continuously heat up, especially the inner coils at the top of the furnace where the heat transfer medium temperature is high, making them prone to overheating and coking. Poor flow field organization of flue gas and heat transfer medium in different coils or different parts of the same coil often leads to uneven heat exchange and local overheating, further aggravating coking. Once coking occurs, the flow resistance and thermal resistance increase, the temperature continues to rise, and coking intensifies, forming a vicious cycle.

[0003] Therefore, there is an urgent need to invent an organic heat carrier furnace that prevents coking to solve the above problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a multi-segment series-parallel anti-coking organic heat carrier furnace, which can avoid excessive temperature difference of the heat transfer medium in the coil, thereby preventing coking.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a multi-segment series-parallel anti-coking organic heat carrier furnace, including a furnace body and a burner located at the bottom of the furnace body. The furnace body is divided into at least two segments from top to bottom. Each segment is equipped with a coil group. Each coil group includes an inner coil and an outer coil connected in parallel. The coil groups in each segment are connected in series and / or in parallel.

[0006] To further prevent excessive local temperature in the inner coil, a thermistor bimetallic strip is provided on the fire-facing side of the uppermost inner coil. The thermistor bimetallic strip is semi-cylindrical and is attached to the outer surface of the fire-facing side of the inner coil. The straight edge on the lower side is fixed to the inner coil. The thermistor bimetallic strip is configured to spring away towards the fire-facing side when the critical temperature is exceeded.

[0007] Furthermore, to prevent flue gas from escaping due to gaps between adjacent coil sections, an inner coil connecting section is provided between the inner coils of adjacent sections, and an outer coil connecting section is provided between the outer coils of adjacent sections.

[0008] Furthermore, to facilitate the adjustment of the heat transfer medium flow rate, the inner and outer coils of each coil group are connected at both ends by a header. The coil groups in each section are also connected in series and / or in parallel through the header. The header is equipped with a resistance adjustment device for adjusting the inlet resistance of the corresponding inner and outer coils.

[0009] To further facilitate quantitative control of the temperature difference between the inner and outer coils, a temperature measuring device is also installed in the manifold. This device measures the temperature of the heat-conducting medium at the outlets of the inner and outer coils. When the temperature difference between the outlet heat-conducting mediums of the inner and outer coils exceeds the set maximum temperature difference, a corresponding resistance adjustment device is activated to reduce the inlet resistance on the higher temperature side and increase the inlet resistance on the lower temperature side.

[0010] Furthermore, to prevent local overheating of the heat transfer medium in the high-temperature section, a residual heat recovery device is installed in the header at the inlet of the uppermost coil assembly.

[0011] A further provision provides a specific structure for a resistance regulating device, wherein the resistance regulating device is a valve installed at the inlet of the inner coil and the outer coil.

[0012] Furthermore, another specific structure of the resistance adjustment device is provided, which consists of a movable guide vane installed in the manifold and a power mechanism connected to the movable guide vane to drive the movable guide vane to swing to the corresponding position.

[0013] Furthermore, the inner coil and the bottom of the furnace body form a radiative heat exchange zone, a first convective heat exchange zone is formed between the inner coil and the outer coil, and a second convective heat exchange zone is formed between the outer coil and the peripheral wall of the furnace body. The upper end of the furnace body is provided with a flue gas outlet.

[0014] The burner is located at the bottom of the radiant heat exchange zone, the top of the radiant heat exchange zone is connected to the top of the first convection heat exchange zone, the bottom of the first convection heat exchange zone is connected to the bottom of the second convection heat exchange zone, and the upper end of the second convection heat exchange zone is connected to the flue gas outlet.

[0015] Furthermore, the uppermost section is the high-temperature section, and the other sections are low-temperature sections. The allowable temperature of the coil assembly in the high-temperature section is higher than that of the coil assembly in the low-temperature section.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects:

[0017] 1. The furnace body is divided into at least two sections from top to bottom. The inner and outer coils in each section are connected in parallel. Through mixing, the temperature difference of the heat transfer medium in the inner and outer coils is reduced, the temperature uniformity is improved, and high-temperature coking is prevented.

[0018] 2. A thermistor bimetallic strip is installed on the fire-facing side of the inner coil. The thermistor bimetallic strip can enhance the heat exchange performance when the temperature of the inner coil is low, and reduce the local heat exchange performance when the temperature of the inner coil rises above the critical temperature, thereby preventing local overheating and coking.

[0019] 3. Monitor the temperature of the heat transfer medium at each outlet and adjust the resistance distribution between the inner and outer coils by adjusting the resistance adjustment device of each inlet header, thereby adjusting the flow distribution of the heat transfer medium and further improving the controllability of temperature distribution;

[0020] 4. The inlet header of the high-temperature section is also equipped with a waste heat recovery device. When the temperature of the heat transfer medium approaches the critical temperature, the waste heat recovery device recovers excess heat, so that the temperature of the heat transfer medium in the high-temperature section is controlled below the critical temperature. This prevents the heat transfer medium from overheating and coking in the high-temperature coil, thereby preventing the coil from burning through, extending the service life of the coil, and improving safety. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the organic heat carrier furnace in Embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the high-temperature section of the organic heat carrier furnace in Embodiment 2 of the present invention;

[0023] Figure 3 This is a schematic diagram of the inner coil with a thermistor bimetallic strip installed in Embodiment 2 of the present invention;

[0024] Figure 4 for Figure 3 A magnified view of a portion of the image;

[0025] Figure 5 This is a schematic diagram of the movable guide vane in Embodiment 3 of the present invention;

[0026] Figure 6 This is a schematic diagram of the organic heat carrier furnace in Embodiment 4 of the present invention;

[0027] In the diagram, 1. Furnace body; 1-1. Flue gas outlet; 2. Burner; 3. Inner coil; 3-1. Thermosensitive bimetallic strip 3-1; 4. Outer coil; 5. Inner coil connection section; 6. Outer coil connection section; 7. Manifold; 7-1. Inlet manifold; 7-2. Outlet manifold; 7-3. Resistance regulating device; 7-4. Waste heat recovery device; 8. High-temperature section; 9. Low-temperature section. Detailed Implementation

[0028] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] Example 1

[0030] like Figure 1 As shown, a multi-segment series-parallel anti-coking organic heat carrier furnace includes a furnace body 1 and a burner 2 located at the bottom of the furnace body 1. The furnace body 1 is divided into at least two segments from top to bottom. Each segment is equipped with coil groups, and each coil group includes an inner coil 3 and an outer coil 4 connected in parallel. The coil groups in each segment are connected in series and / or in parallel. This arrangement ensures that the heat transfer medium in the inner coil 3 and outer coil 4 within the same segment mixes at a more uniform temperature before entering the next segment. This prevents the temperature difference between the heat transfer medium in the inner coil 3 and outer coil 4 from increasing, thereby preventing coking caused by localized overheating.

[0031] like Figure 1 As shown, the inner coil 3 and the bottom of the furnace body 1 form a radiative heat exchange zone; the inner coil 3 and the outer coil 4 form a first convective heat exchange zone; the outer coil 4 and the peripheral wall of the furnace body 1 form a second convective heat exchange zone; and the upper end of the furnace body 1 is provided with a flue gas outlet 1-1; wherein,

[0032] The burner 2 is located at the bottom of the radiant heat exchange zone, the top of the radiant heat exchange zone is connected to the top of the first convection heat exchange zone, the bottom of the first convection heat exchange zone is connected to the bottom of the second convection heat exchange zone, and the upper end of the second convection heat exchange zone is connected to the flue gas outlet 1-1.

[0033] The high-temperature flue gas generated by burner 2 rises in the radiant heat exchange zone, then enters the first convection heat exchange zone from the top of the first convection heat exchange zone, then enters the second convection heat exchange zone from the bottom of the second convection heat exchange zone, and finally exits the furnace body from the flue gas outlet 1-1.

[0034] Because gaps exist between adjacent inner coils 3 and adjacent outer coils 4 after segmentation, therefore, if Figure 1 As shown, an inner coil connecting section 5 is configured between the inner coils 3 of adjacent sections, and an outer coil connecting section 6 is configured between the outer coils 4 of adjacent sections. This configuration fills the gaps through the inner coil connecting section 5 and the outer coil connecting section 6, preventing flue gas from leaking into adjacent heat exchange zones.

[0035] In this embodiment, the uppermost section is the high-temperature section 8, and the other sections are low-temperature sections 9. The allowable temperature of the coil assembly in the high-temperature section 8 is higher than that of the coil assembly in the low-temperature section 9. The coil assemblies in the high-temperature section 8 and the low-temperature section 9 are made of different materials. Selecting different materials according to different operating temperature requirements can greatly reduce manufacturing and replacement costs and enhance applicability.

[0036] In this embodiment, as Figure 1 As shown, the low-temperature section 9 has a section, and the coils of the high-temperature section 8 and the low-temperature section 9 are connected in series.

[0037] Example 2

[0038] like Figure 2 , 3 As shown in Figure 4, the main difference between this embodiment and Embodiment 1 is that a thermistor bimetallic strip 3-1 is arranged on the fire-facing side of the inner coil 3 in the uppermost section. The thermistor bimetallic strip 3-1 is semi-cylindrical and is attached to the outer surface of the fire-facing side of the inner coil 3. The straight edge on the lower side is fixed on the inner coil 3. The thermistor bimetallic strip 3-1 is configured to spring open toward the fire-facing side when the critical temperature is exceeded.

[0039] The thermistor bimetallic strip 3-1 is made of two metal strips with different thermal deformation values ​​bonded together. The metal strip with smaller thermal deformation is on the fire-facing side. As the temperature rises, the deformation of the metal strip on the fire-facing side is smaller than that on the unfire-facing side, causing the thermistor bimetallic strip 3-1 to bend towards the fire-facing side. When the temperature of the inner coil 3 is low, the thermistor bimetallic strip 3-1 is bonded to the inner coil 3. Since the thermistor bimetallic strip 3-1 is metallic, its thermal resistance is very small, and the thermal conductivity resistance accounts for a very small proportion of the total thermal resistance. Therefore, by increasing the outer diameter of the inner coil 3, the heat exchange area is increased, thus enhancing the overall heat exchange performance of the inner coil 3. When the temperature of the inner coil 3 rises above the critical temperature, the thermistor bimetallic strip 3-1 springs open, causing the thermistor bimetallic strip 3-1 to separate from the inner coil. The presence of an air layer between the coils reduces heat transfer efficiency. Since the flue gas flows upwards and washes against the wall of the inner coil 3 for heat exchange, the retracted thermistor bimetallic strip 3-1 blocks this part of the inner coil 3, preventing direct radiative and convective heat exchange between the inner coil 3 and the flue gas. Furthermore, the contact area between the thermistor bimetallic strip 3-1 and the inner coil 3 is reduced to a straight edge, significantly increasing thermal resistance. This results in a significant reduction in localized heat exchange of the inner coil 3, preventing localized overheating.

[0040] Example 3

[0041] like Figure 1 , 2As shown in Figure 4, the main difference between this embodiment and Embodiment 1 or Embodiment 2 is that the inner coil 3 and outer coil 4 of each coil group are connected at both ends by a manifold 7. The coil groups within each section are also connected in series and / or in parallel through the manifold 7. The manifold 7 is divided into an inlet manifold 7-1 and an outlet manifold 7-2. The inlets of the inner coil 3 and outer coil 4 of each coil group are connected through the inlet manifold 7-1, and the outlets are connected through the outlet manifold 7-2. The inlet manifold 7-1 is equipped with a resistance regulating device 7-3 for adjusting the inlet resistance of the corresponding inner coil 3 and outer coil 4. The flow rate is adjusted by regulating the local inlet resistance using the resistance regulating device 7-3, thereby changing the heat exchange and controlling the temperature of the heat transfer medium. When coking has occurred, the flow rate in the coked coil can be increased by pulse, and the high-flow-rate flushing removes the coking deposits.

[0042] In this embodiment, the resistance adjustment device 7-3 can adopt various structures, including but not limited to the following two:

[0043] In the first type, the resistance regulating device 7-3 is a valve installed at the inlet of the inner coil 3 and the outer coil 4. The valve is easy to install and operate, and can control the resistance of each coil individually.

[0044] The second type comprises a movable guide vane installed within the manifold 7 and a power mechanism connected to the movable guide vane to drive it to swing to a corresponding position. The structure of the movable guide vane is as follows: Figure 5 As shown, the movable guide vane reduces the adjustment steps, and the local resistance of the coil is small on the side the guide vane points to. By controlling the swing of the movable guide vane through the power mechanism, the flow distribution between the inner coil 3 and the outer coil 4 can be easily realized, reducing the amount of operation.

[0045] In this embodiment, to more accurately and quantitatively adjust the inlet local resistance difference between the inner coil 3 and the outer coil 4, a temperature measuring device is installed in the outlet manifold 7-2. This device measures the temperature of the heat-conducting medium at the outlets of the inner coil 3 and the outer coil 4. When the temperature difference between the outlet heat-conducting mediums of the inner coil 3 and the outer coil 4 exceeds the set maximum temperature difference, the corresponding resistance adjusting device 7-3 operates to reduce the inlet resistance on the higher-temperature side and increase the inlet resistance on the lower-temperature side. Through feedback adjustment of the outlet temperature difference and the inlet resistance difference, quantitative control of the temperature difference between the heat-conducting mediums of the inner coil 3 and the outer coil is achieved, preventing uneven temperature distribution.

[0046] like Figure 2As shown, the inlet manifold 7-1 of the uppermost coil assembly is equipped with a waste heat recovery device 7-4. To automatically prevent local overheating of the heat transfer medium in the high-temperature section, when the temperature measured by the temperature measuring device on the outlet manifold 7-2 of the high-temperature section 8 approaches the critical temperature, the waste heat recovery device 7-4 of the high-temperature section 8 operates. Through feedback regulation from outlet overheating to inlet cooling, the maximum temperature of the heat transfer medium is quantitatively controlled to prevent overheating.

[0047] Example 4

[0048] like Figure 6 As shown, the main difference between this embodiment and Embodiment 1 is that the low-temperature section 9 has two sections, and the header 7 is divided into an inlet header 7-1 and an outlet header 7-2. The inlets of the inner coil 3 and outer coil 4 of each coil group are connected through the inlet header 7-1, and the outlets are connected through the outlet header 7-2. The coil groups of the high-temperature section 8 and the upper low-temperature section 9 are connected in parallel and then connected in series with the lower coil group. This arrangement allows for flexible arrangement of the flow within the coils. In actual use, the number of low-temperature sections 9 can be increased as needed, and various forms of series and parallel connections can be made between the sections as required to improve the adaptability of the heat exchange arrangement. Especially for large organic heat carrier furnaces, multi-section arrangements are also more convenient for manufacturing, transportation, installation, replacement, and other operations.

[0049] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A multi-segment series-parallel anti-coking organic heat carrier furnace, comprising a furnace body (1) and a burner (2) located at the bottom of the furnace body (1), characterized in that, The furnace body (1) is divided into at least two sections from top to bottom. Each section is equipped with a coil group. Each coil group includes an inner coil (3) and an outer coil (4) connected in parallel. The coil groups in each section are connected in series and / or in parallel. The inner coil (3) in the uppermost section is provided with a thermistor bimetallic strip (3-1) on the fire-facing side. The thermistor bimetallic strip (3-1) is semi-cylindrical and is attached to the outer surface of the inner coil (3) on the fire-facing side. The straight edge on the lower side is fixed to the inner coil (3). The thermistor bimetallic strip (3-1) is configured to spring open towards the fire-facing side when the critical temperature is exceeded. The thermistor bimetallic strip (3-1) is made of two metal strips with different thermal deformations bonded together. The metal strip with smaller thermal deformation is on the fire-facing side.

2. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 1, characterized in that, An inner coil connecting section (5) is provided between the inner coils (3) of adjacent sections, and an outer coil connecting section (6) is provided between the outer coils (4) of adjacent sections.

3. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 1, characterized in that, The inner coil (3) and outer coil (4) of each coil group are connected at both ends by a header (7). The coil groups in each section are also connected in series and / or in parallel through the header (7). The header (7) is equipped with a resistance adjustment device (7-3) for adjusting the inlet resistance of the corresponding inner coil (3) and the corresponding outer coil (4).

4. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 3, characterized in that, The manifold (7) is also equipped with a temperature measuring device, which is used to measure the temperature of the heat transfer medium at the outlet of the inner coil (3) and the outer coil (4). When the temperature difference between the outlet heat transfer medium of the inner coil (3) and the outer coil (4) exceeds the set maximum temperature difference, the corresponding resistance adjustment device (7-3) works to reduce the inlet resistance on the higher temperature side and increase the inlet resistance on the lower temperature side.

5. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 3, characterized in that, The header (7) located at the inlet of the uppermost coil assembly is equipped with a residual heat recovery device (7-4).

6. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 3, characterized in that, The resistance regulating device (7-3) is a valve installed at the inlet of the inner coil (3) and the outer coil (4).

7. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 3, characterized in that, The resistance adjustment device (7-3) consists of a movable guide vane installed in the header (7) and a power mechanism connected to the movable guide vane to drive the movable guide vane to swing to the corresponding position.

8. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 1, characterized in that, The inner coil (3) and the bottom of the furnace body (1) form a radiant heat exchange zone; the inner coil (3) and the outer coil (4) form a first convective heat exchange zone; the outer coil (4) and the peripheral wall of the furnace body (1) form a second convective heat exchange zone; and the upper end of the furnace body (1) is provided with a flue gas outlet (1-1). The burner (2) is located at the bottom of the radiant heat exchange zone, the top of the radiant heat exchange zone is connected to the top of the first convection heat exchange zone, the bottom of the first convection heat exchange zone is connected to the bottom of the second convection heat exchange zone, and the upper end of the second convection heat exchange zone is connected to the flue gas outlet (1-1).

9. The multi-segment series-parallel anti-coking organic heat carrier furnace according to claim 1, characterized in that, The uppermost section is the high-temperature section (8), and the other sections are low-temperature sections (9). The allowable temperature of the coil group in the high-temperature section (8) is higher than the allowable temperature of the coil group in the low-temperature section (9).

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