Compact steam reforming unit

Abstract

This invention provides a compact steam reforming apparatus, comprising a burner, a combustion chamber, a reactor, a first preheating module, and a second preheating module. The burner is configured to generate flue gas through combustion in the combustion chamber. The reactor receives radiative heat from the flue gas generated in the combustion chamber and is used to generate reforming products from a mixture of hydrocarbon feedstock gas and H2O steam. The first preheating module is implemented to recover heat from the flue gas and includes an air preheating pipe and a steam generator. The second preheating module is implemented to recover heat from the reforming products. The second preheating module surrounds the first preheating module and includes a mixed gas preheating pipe. The second preheating module is thermally insulated from the external environment. This invention can improve the operating efficiency of the reforming apparatus and increase energy utilization.

Description

Technical Field

[0001] The present invention relates to a steam reforming apparatus, and more particularly, to a compact steam reforming apparatus. Background Technology

[0002] Compact steam reforming units employ advanced small-channel reactors and microparticle catalyst technology, significantly reducing the overall size and weight of the unit. Furthermore, the compact unit offers faster response times, enabling rapid adjustment of reaction parameters to meet hydrogen requirements in various applications. However, current compact steam reforming units suffer from the technical challenge of inadequate temperature distribution. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a compact steam reforming device that can utilize the system's internal heat in a phased manner, resulting in high efficiency and energy savings.

[0004] This invention provides a compact steam reforming apparatus, comprising: a burner and a combustion chamber, the burner being configured to generate flue gas through combustion in the combustion chamber; a reactor, the reactor being radiated and heated by the flue gas generated in the combustion chamber and used to generate reforming products from a mixture of hydrocarbon feedstock gas and H2O steam; a first preheating module configured to recover heat from the flue gas, the first preheating module having an air preheating pipe and a steam generator arranged therein; and a second preheating module configured to recover heat from the reforming products, the second preheating module surrounding the first preheating module, the second preheating module having a mixed gas preheating pipe arranged therein, and the second preheating module being thermally insulated from the outside.

[0005] Preferably, the steam generator includes a demineralized water preheating pipe section and a vaporization superheating pipe section, which are fluidly connected; wherein the demineralized water preheating pipe section is configured to exchange heat with the flue gas in a counter-current manner, and the vaporization superheating pipe section is configured to exchange heat with the flue gas in a co-current manner.

[0006] Preferably, the demineralized water preheating pipe section is configured to include a coil section and a straight pipe section, with one end of the straight pipe section connected to the coil section and the other end of the straight pipe section connected to the vaporization superheating pipe section; wherein, the coil section is located downstream of the flue gas flow direction.

[0007] Furthermore, the first preheating module is equipped with a first ring pipe, which is configured to receive hydrocarbon feed gas and H2O steam transported by the vaporized superheated pipe section to obtain a mixed gas.

[0008] Furthermore, the upper side of the compact steam reforming unit is provided with a connecting pipe, one end of which is in fluid communication with the first annular pipe, and the other end of which is in fluid communication with the mixed gas preheating pipe.

[0009] Furthermore, a second ring pipe is provided on the upper side of the first preheating module, and the connecting pipe is configured to be fluidly connected to the second ring pipe in the downstream direction of the mixed gas; the mixed gas preheating pipe is configured as a plurality of mixed gas preheating coils, and the second ring pipe is connected to the plurality of mixed gas preheating coils in a split manner.

[0010] Furthermore, a third ring pipe is provided on the upper side of the second preheating module, and the third ring pipe has a reforming product output end extending outward; a tube sheet is provided on the top of the second preheating module, and the tube sheet has a first through hole and a second through hole; wherein, the first through hole is configured to allow the second ring pipe to be in fluid communication with a plurality of mixed gas preheating coils; the second through hole is in fluid communication with the third ring pipe, and the second through hole provides an outflow channel for the reforming product.

[0011] In some implementations, the air preheating tube is configured as a coil, surrounding the outside of the steam generator.

[0012] Furthermore, an outer mixing gas coil is provided on the outside of the reactor, and a mixing gas inlet is provided at the bottom of the reactor; the outer mixing gas coil is in fluid communication with the mixing gas preheating pipe in the upstream direction of the mixing gas, and in fluid communication with the mixing gas inlet in the downstream direction of the mixing gas.

[0013] Furthermore, a fourth ring pipe is provided between the second preheating module and the reactor; the mixed gas preheating pipe is constructed as several mixed gas preheating coils, which merge and terminate inside the fourth ring pipe; the outer mixed gas coil is constructed as several coils, which diverge and start outside the fourth ring pipe.

[0014] The features and advantages of this disclosure include: by rationally arranging the heat exchange pipelines in the first preheating module and the second preheating module, the present invention utilizes the heat of flue gas and reforming products in a gradient manner, thereby improving the operating efficiency of the reforming unit, increasing energy utilization, and reducing energy consumption. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A three-dimensional schematic diagram of a compact steam reforming unit is shown;

[0017] Figure 2 A top view schematic diagram of a compact steam reforming unit is shown;

[0018] Figure 3A It shows along Figure 2A schematic diagram of a compact steam reforming unit cut along the AA direction;

[0019] Figure 3B yes Figure 3A An enlarged diagram of X in the middle;

[0020] Figure 3C yes Figure 3A A magnified diagram of Y in the diagram;

[0021] Figure 4A It shows along Figure 2 A three-dimensional schematic diagram of a compact steam reforming unit partially sectioned along the middle BB direction;

[0022] Figure 4B yes Figure 4A A magnified diagram of Z in the diagram. Detailed Implementation

[0023] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0024] Figure 1 A perspective schematic view of the compact steam reforming apparatus 100 of the present invention is shown. Figure 2 A top view of a compact steam reforming unit 100 is shown. The steam reforming unit 100 is generally cylindrical and has an outer casing 103, with its material inlet or material inlet connection preferably located at the top of the unit. Specifically, the top of the unit is provided with an air inlet 78, a feed gas inlet 72, a fuel gas inlet 74, and a demineralized water inlet 76. Furthermore, the top of the unit also has a flue gas outlet 82, and a reforming product outlet 84 is located on a side near the top of the unit.

[0025] refer to Figures 3A-4B The compact steam reforming unit 100 includes a burner 101, a combustion chamber 102, and a reactor 10 located within an outer casing 103. Fuel gas supplied to the burner 101 is burned in the combustion chamber 102 with combustion air to produce high-temperature flue gas. The heat from the high-temperature flue gas is radiated to the reactor 10, where the reactor 10 mixes the hydrocarbon feedstock gas and H2O steam to generate reforming products. According to a preferred embodiment of the invention, both the hydrocarbon feedstock gas and the fuel gas supplied to the burner 101 are natural gas, and the reforming products are syngas containing hydrogen and carbon monoxide.

[0026] Reactor 10 is located at the bottom of a compact steam reforming unit 100. Reactor 10 has a cup-shaped inner wall and a cup-shaped outer wall. The interior of reactor 10 is constructed as an annular space defined by the inner and outer walls, and catalyst 14 is arranged within this annular space. Reactor 10 is generally cup-shaped, and a mixed gas inlet 12 is located at the bottom of reactor 10. Specifically, the bottom of the outer wall of reactor 10 has a mixed gas inlet 12, and the bottom of reactor 10 has a pipe 15 connected to the outer wall. The pipe 15 is in fluid communication with the annular space of reactor 10 through the mixed gas inlet 12. The sidewall of pipe 15 has a connecting hole 19, through which the mixed gas further enters the annular space of reactor 10 via the mixed gas inlet 12 to participate in the chemical reaction. The bottom of reactor 10 has a first perforated plate 16 located at the mixed gas inlet 12, and the top of reactor 10 has an annular second perforated plate 17 located between the inner and outer walls. The arrangement of the first perforated plate 16 and the second perforated plate 17 facilitates both the inflow and outflow of fluid from the reactor 10 and the confinement of the catalyst within a certain space. Furthermore, when the compact steam reforming unit 100 is in its normal position, the first perforated plate 16 provides support for the catalyst; when the compact steam reforming unit 100 is inverted, the second perforated plate 17 provides support for the catalyst 14.

[0027] In some embodiments, for convenient replacement of the catalyst 14, the first perforated plate 16 is detachably connected to the tube body 15, and the second perforated plate 17 is fixedly connected to the inner and outer side walls. Specifically, a plug 18 is provided inside the tube body 15, and the plug is detachably connected to the tube body 15. A bracket is provided at the upper end of the plug 18, and the first perforated plate 15 is fixedly connected to the bracket. Preferably, the plug 18 is filled with heat-insulating filler for heat insulation. More specifically, flanges are provided at the lower ends of the tube body 15 and the plug, and the tube body and the plug are detachably connected by bolts connected to the flanges. The flange of the tube body 15 is fixedly connected to the bottom wall of the outer casing 103.

[0028] Combustion chamber 102 is arranged inside the cup-shaped reactor 10, and there is a certain distance between combustion chamber 102 and the inner wall of reactor 10. Burner 101 can be set at the top of combustion chamber 102. After the high-temperature flue gas flows out from the bottom of combustion chamber 102, it first provides radiant heat for catalytic reforming reaction through the inner wall of reactor 10, and then flows to flue gas outlet 82 at the top of the device. The compact steam reforming device 100 has a longitudinally extending mandrel 105 in the middle, which provides a fuel gas flow channel for burner 101. Fuel gas inlet 74 is set at the top of mandrel 105, and the bottom of mandrel 105 is connected to burner 101.

[0029] Continue to refer to Figure 3A , Figure 3BA first preheating module 20 and a second preheating module 30 are provided above the cup-shaped reactor 10. The first preheating module 20 is configured to recover heat from the flue gas, and the second preheating module 30 is configured to recover heat from the reforming products (e.g., syngas). The first preheating module 20 is configured to include a first shell 21, which may be separately or integrally formed as an upward extension of the inner sidewall of the reactor 10; preferably, the first shell 21 extends upward to the top of the compact steam reforming unit 100. The second preheating module 30 is configured to include a second shell 31, which may be separately or integrally formed as an upward extension of the outer sidewall of the reactor 10. In some embodiments, the upper end of the first shell 21 extends beyond the upper end of the second shell 31; a heat-insulating filling layer 104 is provided between the reactor 10 and the outer shell 103, between the second shell 31 and the outer shell 103, and between the upper portion of the first shell 21 extending beyond the second shell 31 and the outer shell.

[0030] refer to Figures 3A-4B The first preheating module 20 recovers heat from the flue gas, and the flue gas flow channel is defined by the outer walls of the first housing 21 and the mandrel 105. A steam generator 26 is arranged in the first preheating module 20. Demineralized water flowing in from the demineralized water inlet 76 passes through the steam generator 26 to obtain H2O vapor components in the mixed gas required for the reforming reaction. In some embodiments, the steam generator 26 is configured to include a demineralized water preheating section 262 and a vaporization superheating section 264. The demineralized water first enters the demineralized water preheating section 262 for preheating, and then enters the vaporization superheating section 264. The demineralized water preheating section 262 and the vaporization superheating section 264 can exchange heat with the flue gas counter-currently or in parallel. In some embodiments, the demineralized water preheating section 262 is configured to exchange heat with the flue gas counter-currently, which is beneficial for the demineralized water to fully absorb heat. In some embodiments, the vaporization superheating section 264 is configured to exchange heat with the flue gas in the co-current direction. The inlet of the vaporization superheater section 264 is located at the lower side, and the outlet is located at the upper side. This arrangement allows the preheated demineralized water to enter the vaporization superheater section 264 from the lower inlet, which facilitates the upward flow of the steam-water mixture. Preferably, the diameter of the vaporization superheater section 264 is larger than the diameter of the demineralized water preheater section 262. After absorbing heat, the demineralized water forms a steam-water mixture in the vaporization superheater section 264, significantly increasing its volume. The increased diameter of the vaporization superheater section 264 helps to reduce the flow velocity of the steam-water mixture (or steam) within the pipe, thus reducing the system pressure drop.

[0031] Specifically, see Figure 4BThe demineralized water preheating section 262 is configured to include a coil section 262a and a straight section 262b, and the vaporization superheating section 264 is connected to the coil section 262a via the straight section 262b. Preferably, the vaporization superheating section 264 is configured as a coil. The coil diameter and coil height of the coiled tubes of the coil section 262a and the vaporization superheating section 264 can be selected according to the required heat exchange surface area. Preferably, in the flue gas flow direction, the coil section 262a is located downstream. As the flue gas flows from upstream to downstream, the flue gas temperature gradually decreases. The large temperature difference between the low-temperature demineralized water entering the coil section 262a and the downstream flue gas is beneficial for heat exchange, resulting in a low flue gas temperature exiting the compact steam reforming unit 100, improving the overall thermal energy utilization of the unit, and reducing losses. The straight section 262b extends parallel to the mandrel 105 and connects to the inlet of the vaporization superheating section 264. Furthermore, the coil diameter of the vaporization superheating tube section 264 is larger than the coil diameter of the demineralized water preheating tube section 262a, which helps to increase the heat exchange surface area of ​​the vaporization superheating tube section 264, allowing the medium flowing through the vaporization superheating tube section 264 to fully absorb heat. Specifically, both coil 262a and vaporization superheating tube section 264 are single-layer coils.

[0032] Furthermore, an air preheating pipe 22 is also arranged in the first preheating module 20. In some embodiments, the air preheating pipe 22 is configured as multiple coils, and the air flowing in from the air inlet 78 passes through the air preheating pipe 22 and exchanges heat with the flue gas in a countercurrent flow before entering the burner 101 as a combustion-supporting gas. The coil diameter and coil height of the air preheating pipe 22 can be selected according to the required heat exchange surface area. Preferably, the pipe diameter of the air preheating pipe 22 is larger than the pipe diameter of the steam generator 26, making it easier to arrange the air preheating pipe 22 around the outside of the steam generator 26. On the other hand, the coil gap of the air preheating pipe 22 is relatively large, which facilitates the flue gas to pass through the gap, allowing the flue gas to exchange heat with the demineralized water preheating pipe section 262. Alternatively, the air preheating pipe 22 can be arranged around the mandrel 105 and located inside the steam generator 26. Alternatively, when the air preheating pipe 22 is located inside the steam generator 26, it can be integrated with the burner 101, for example, as an air self-preheating combustion device.

[0033] See Figure 3A , Figure 3C In some embodiments, the air inlet 78, flue gas outlet 82, and fuel gas inlet 74 are coaxially arranged, and both the air inlet 78 and the flue gas outlet 82 are annular. The flue gas outlet 82 surrounds the fuel gas inlet 74, and the air inlet 78 surrounds the flue gas outlet 82. Optionally, an annular air cavity 23 is provided on the upper inner side of the first housing 21, and the air inlet 78 is connected to the air preheating pipe 22 through the air cavity 23. The flue gas passage is located inside the air cavity 23.

[0034] refer to Figure 4A , Figure 4B Downstream of the flue gas flow in the first preheating module 20 and at the end of the steam generator 26, a first annular pipe 28 is provided. The first annular pipe 28 has a raw material gas receiving end 281, a steam receiving end 282, and a mixed gas output end 283. The end of the steam generator 26 (e.g., the end of the vaporization superheater section 264) is connected to the steam receiving end 282, and the raw material gas inlet 72 at the top of the device is fluidly connected to the raw material gas receiving section 281. The first annular pipe 28 provides a channel for mixing the raw material gas and H2O steam. Further, see... Figure 4A The device has a connecting pipe 41 at the top. One end of the connecting pipe 41 is in fluid communication with the mixed gas output terminal 283, and the other end is in fluid communication with the mixed gas preheating pipe 32 (described in detail later) located in the second preheating module 30. The first preheating module 20 and the second preheating module 30 are independently configured. The first ring pipe 28 is located in the first preheating module 20, and the mixed gas preheating pipe 32 is located in the second preheating module. The connecting pipe 41 enables the first ring pipe 28 and the mixed gas preheating pipe 32 to be in fluid communication. Specifically, the connecting pipe 41 includes a horizontal pipe section and a vertical pipe section, with the two vertical pipe sections connected to both ends of the horizontal pipe section. The horizontal pipe section is located outside the outer casing 103. One of the vertical pipe sections extends through the outer casing 103 and enters the first preheating module 20, connecting to the mixed gas output terminal 283 of the first ring pipe 28. The other vertical pipe section extends through the outer casing and connects to the mixed gas preheating pipe 32. The partial connecting pipe 41 is located outside the outer casing 103, which reduces the internal space requirement of the outer casing 103 and helps to reduce the volume and weight of the compact steam reforming unit 100.

[0035] refer to Figure 3A , Figure 4A A second annular pipe 44 is provided in the heat insulation filling layer 104 near the upper end of the first housing 21. The second annular pipe 44 is in fluid communication with the connecting pipe 41 in the upstream direction of the mixed gas and in fluid communication with the mixed gas preheating pipe 32 in the downstream direction of the mixed gas. Specifically, a tube plate 46 is provided at the top of the second housing 31. The tube plate 46 has a first through hole 461, and the second annular pipe 44 is in fluid communication with the mixed gas preheating pipe 32 through the first through hole 461 on the tube plate 46.

[0036] refer to Figure 3A , Figure 4AThe second preheating module 30 recovers heat from the reformed product. The flow channel for the reformed product is defined by the first shell 21, the second shell 31, and the tube sheet 46. The mixed gas preheating pipe 32 is configured as several mixed gas preheating coils, and the second annular pipe 44 is connected to the starting ends of several mixed gas preheating coils in a branching manner. Correspondingly, the tube sheet 46 is provided with several first through holes 461, and each mixed gas preheating coil extends downwards after passing through the first through hole 461. The reformed product output from the cup-shaped reactor 10 enters the second preheating module 30 from the top of the reactor 10, and the reformed product exchanges heat with the mixed gas countercurrently.

[0037] refer to Figure 4A , Figure 4B The tube sheet 46 is also provided with a second through hole 462. A third ring pipe 45 is provided in the heat insulation filling layer 104 near the upper end of the second housing 31. The third ring pipe 45 is provided with a reforming product output end 45a, and a reforming product outlet 84 is formed on the reforming product output end 45a. The second through hole 462 on the tube sheet is in fluid communication with the third ring pipe 45. Specifically, there may be multiple second through holes 462, and each second through hole 462 is connected to the third ring pipe 45 via a bend. After the reforming product reaches the top of the second preheating module 30, it enters the third ring pipe 45 through the second through hole 462 on the tube sheet 46, and further flows out of the device 100 from the third ring pipe 45.

[0038] Further, refer to Figure 3A , Figure 4A An outer mixing gas coil 62 is provided in the heat insulation filling layer 104 on the outside of the reactor 10. In some embodiments, the outer mixing gas coil 62 is fluidly connected to the end of the mixing gas preheating pipe 32 in the upstream direction of the mixing gas and terminates at the communication hole 19 at the bottom of the reactor 10 in the downstream direction of the mixing gas. Alternatively, the outer mixing gas coil 62 terminates at the mixing gas inlet 12 at the bottom of the reactor 10 in the downstream direction of the mixing gas.

[0039] Preferably, refer to Figure 3A , Figure 4AA fourth annular pipe 47 is provided between the reactor 10 and the second preheating module 30. Specifically, the fourth annular pipe 47 can be located between the top of the outer wall of the reactor 10 and the bottom of the second shell 31. The fourth annular pipe 47 is fluidly connected upstream of the mixed gas to the mixed gas preheating pipe 32 and downstream of the mixed gas to the outer mixed gas coil 62. The mixed gas preheating pipe 32 terminates inside the fourth annular pipe 47, and the outer mixed gas coil 62 begins outside the fourth annular pipe 47. The mixed gas preheating pipe 32 is located inside the second preheating module 30, and the outer mixed gas coil 62 is located outside the reactor 10 (i.e., outside the second preheating module 30). The fourth annular pipe 47 not only allows fluid communication between the mixed gas preheating pipe 32 and the outer mixed gas coil 62, but also allows for further mixing of the mixed gas within the fourth annular pipe 47, achieving both uniform mixing and balanced gas flow rate.

[0040] refer to Figure 2 , Figure 3A , Figure 3B and Figure 3C Fuel gas 91 enters the spindle 105 through fuel gas inlet 74 and is delivered to the burner 101. Combustion air 92 enters the air chamber 23 through air inlet 78 and is delivered to the combustion chamber 102 via air pipe heat pipe 22. Under the action of combustion air 92, the burner 101 combusts the fuel gas 91 to produce flue gas 93. Flue gas 93 provides heat energy to the reactor 10 and the steam generator 26 and air preheating pipe 22 located in the first preheating module 20. Demineralized water 94 enters the demineralized water flow channel through demineralized water inlet 76, and absorbs the heat energy of the flue gas to form H2O steam as it passes through the demineralized water preheating pipe section 262 and the vaporization superheating pipe section 264. Raw material gas flows in from raw material gas inlet 72, and the raw material gas and H2O steam mix in the first ring pipe to form a mixed gas. After passing through connecting pipe 41 and second ring pipe 44, the mixed gas absorbs the heat energy of the reforming product when it flows into the mixed gas preheating coil. After passing through fourth ring pipe 47 and outer mixed gas coil 62, it flows into reactor 10. The mixed gas reacts under the action of catalyst 14 to generate reforming product 97. Reforming product 97 flows out through reforming product outlet 84 of third ring pipe 45.

[0041] The above descriptions are merely a few embodiments of this disclosure. Those skilled in the art can make various modifications or variations to the embodiments of this disclosure based on the content disclosed in the application documents without departing from the spirit and scope of this disclosure.

Claims

1. A compact steam reforming unit, characterized in that, include: A burner and a combustion chamber, wherein the burner is configured to produce flue gas through combustion in the combustion chamber; The reactor is radiated and heated by the flue gas produced in the combustion chamber and is used to generate reforming products from a mixture of hydrocarbon feedstock gas and H2O steam. The first preheating module is configured to recover heat from the flue gas, and the first preheating module is equipped with an air preheating pipe and a steam generator. as well as The second preheating module is configured to recover heat from the reforming product. The second preheating module surrounds the first preheating module and has a mixed gas preheating pipe arranged in it. The second preheating module is thermally insulated from the outside. The steam generator includes a demineralized water preheating tube section and a vaporization superheating tube section. The demineralized water preheating tube section is configured to exchange heat with the flue gas in a counter-current manner, and the vaporization superheating tube section is configured to exchange heat with the flue gas in a co-current manner. The demineralized water preheating pipe section is configured to include a coil section and a straight pipe section. The coil section is located downstream of the flue gas flow direction. One end of the straight pipe section is in fluid communication with the coil section, and the other end of the straight pipe section is in fluid communication with the vaporization superheating pipe section. The vaporization superheated pipe section is configured as a coil, the pipe diameter of the vaporization superheated pipe section is larger than the pipe diameter of the demineralized water preheated pipe section, and the coiling diameter of the vaporization superheated pipe section is larger than the coiling diameter of the demineralized water preheated pipe section.

2. The compact steam reforming unit according to claim 1, characterized in that, The first preheating module is provided with a first ring pipe, which is configured to receive hydrocarbon feed gas and H2O steam transported by the vaporization superheating pipe section to obtain a mixed gas.

3. The compact steam reforming unit according to claim 2, characterized in that, The compact steam reforming unit is provided with a connecting pipe on its upper side. One end of the connecting pipe is in fluid communication with the first annular pipe, and the other end of the connecting pipe is in fluid communication with the mixed gas preheating pipe.

4. The compact steam reforming unit according to claim 3, characterized in that, The upper side of the first preheating module is provided with a second ring pipe, and the connecting pipe is configured to be fluidly connected to the second ring pipe in the downstream direction of the mixed gas; The gas preheating pipe is configured as a plurality of gas preheating coils, and the second ring pipe is connected to the plurality of gas preheating coils in a branching manner.

5. The compact steam reforming unit according to claim 4, characterized in that, The upper side of the second preheating module is provided with a third ring pipe, and the third ring pipe is provided with a reforming product output end extending outward; The top of the second preheating module is provided with a tube sheet, and the tube sheet is provided with a first through hole and a second through hole; The first through-hole is configured to allow the second ring pipe to be in fluid communication with the plurality of mixed gas preheating coils; the second through-hole is in fluid communication with the third ring pipe, and the second through-hole provides an outflow channel for the reforming product.

6. The compact steam reforming unit according to claim 1, characterized in that, The air preheating tube is configured as a coil and surrounds the outside of the steam generator.

7. The compact steam reforming unit according to claim 1, characterized in that, The reactor is provided with an outer mixing gas coil on the outside and a mixing gas inlet at the bottom of the reactor; The outer mixing coil is in fluid communication with the mixing preheating pipe in the upstream direction of the mixing gas and in fluid communication with the mixing gas inlet in the downstream direction of the mixing gas.

8. The compact steam reforming unit according to claim 7, characterized in that, A fourth loop pipe is provided between the second preheating module and the reactor; The gas mixture preheating pipe is configured as a plurality of gas mixture preheating coils, which converge and terminate inside the fourth ring pipe. The outer mixing coil is constructed as several coils, and the outer mixing coil originates outside the fourth ring pipe in a branching manner.

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