Reaction system and method for producing syngas from biogas combined with reforming

Abstract

The present application relates to the technical field of methane conversion and syngas preparation, in particular to an integrated heat exchange-reforming reaction system, application of the integrated heat exchange-reforming reaction system and a method for preparing syngas by reforming methane-rich gas, the system comprising at least one parallel reaction tube, the top of the reaction tube being provided with a feed pipe and a discharge pipe, the shell of the reaction tube being divided into a heat recovery zone, a heat exchange reaction zone and a preheating zone from top to bottom; the heat exchange reaction zone and the preheating zone being externally heated; the heat recovery zone being provided with a heat exchange component; wherein the heat exchange reaction zone is provided with a catalyst bed layer arranged in a ring around a center pipe, and the heat exchange reaction zone is divided into a heat exchange part and a reaction part; the two ends of the heat exchange component being connected with the feed pipe and the center pipe respectively. The application of the system in preparing syngas by reforming methane-rich gas has a high methane conversion rate and total carbon atom utilization rate.

Description

Technical Field

[0001] This invention relates to the field of methane conversion and syngas preparation technology, specifically to an integrated heat exchange-reforming reaction system, an application of the integrated heat exchange-reforming reaction system, and a method for reforming methane-rich gas to produce syngas. Background Technology

[0002] Methane steam reforming and dry reforming of methane and carbon dioxide are both strongly endothermic reactions. Due to thermodynamic equilibrium limitations, the reaction outlet temperature must reach at least 800℃, or even 900℃, to achieve the desired methane conversion rate. Therefore, this process has high energy consumption. Industrially, methane or hydrocarbon reforming reactors often use reaction tubes with an inner diameter of 70-150mm and a length typically of 10-14m, with dozens or even hundreds of tubes placed in a high-temperature combustion furnace. The large diameter of the reforming tubes increases the internal thermal resistance and radial temperature difference of the bed, reducing the apparent reaction activity of the catalyst and increasing the risk of carbon buildup on the inner wall of the tubes. Secondly, traditional reforming furnaces use an L-shaped furnace, including a radiant section and a convection section. Although the convection section can achieve flue gas heat recovery and preheating and vaporization of the feedstock, the overall footprint is large. In addition, the high-temperature conversion gas from the outlet of the traditional conversion process needs to be fed into the steam generator to produce medium-pressure steam. This is beneficial for large chemical or oil refineries to improve the overall energy utilization efficiency, but for biogas plants that are relatively small in scale and do not have a steam pipeline network, how to improve the energy utilization efficiency of the reaction unit is a problem that needs to be solved.

[0003] CN112236223A discloses a steam reforming reaction system heated by resistance, employing a structured conductive material to support a ceramic coating, on which a catalytically active material is loaded; the structured catalyst is heated to at least 500°C by an electric current. This reaction system improves the apparent activity and conversion efficiency of the catalyst by reducing the catalyst diffusion distance and employing a more efficient heating method, while reducing the size of the reaction system. However, the amount of coated catalyst is limited, and particulate catalyst still needs to be packed into the channel to increase the total amount of catalyst. On the other hand, the coating is not easy to replace after the catalyst is deactivated.

[0004] CN111433151A discloses a system and method for producing syngas with a low H2 / CO ratio. The reactor for producing syngas comprises two reactors connected in series: a preheated reaction reactor (ATR) and a post-reactor reactor containing a feed preheating pipe. The product gas is generated by mixing the converted gas from the ATR with a preheated CO2-rich gas stream within the post-reactor bed. Eliminating flame heating reduces system energy consumption, and the high- and low-temperature gas mixing and cooling helps suppress the Boudouard carbonization reaction, thereby reducing the risk of metal dust formation. However, the primary function of the post-reactor is to perform a reverse reaction of CO2 and hydrogen to reduce the H2 / CO ratio of the mixed gas; it does not contribute to methane conversion.

[0005] The above-mentioned existing technologies mainly have the following problems: (1) low methane conversion rate; (2) large thermal resistance of traditional reaction tubes, large radial temperature difference, low reaction efficiency, and high risk of carbon buildup; (3) traditional converters occupy a large area and the heat exchange network is complex and not suitable for skid-mounted devices; (4) traditional processes produce a large amount of steam as a by-product, which is suitable for large chemical or oil refineries. For small biogas application scenarios, improving the energy utilization efficiency of the conversion unit is the main problem. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical problems and provide an integrated heat exchange-reforming reaction system, an application of the integrated heat exchange-reforming reaction system, and a method for reforming methane-rich gas to produce natural gas. This system integrates the vaporization, preheating, reforming reaction, and heat recovery of the reformed gas in the same reaction tube, which not only simplifies the process flow, reduces the equipment footprint, and improves the energy utilization rate of the reforming reaction, but also effectively improves the methane conversion rate in methane-rich gas and increases the total carbon atom utilization rate.

[0007] To achieve the above objectives, the first aspect of the present invention provides an integrated heat exchange-reforming reaction system, the system comprising at least one parallel reaction tube, wherein a feed pipe and a discharge pipe are provided at the top of the reaction tube, and the shell of the reaction tube is divided into a heat recovery zone, a heat exchange reaction zone and a preheating zone from top to bottom; the heat exchange reaction zone and the preheating zone are heated by external means; and the heat recovery zone is provided with heat exchange components.

[0008] The heat exchange reaction zone is provided with a catalyst bed arranged in a ring around the central tube, and the heat exchange reaction zone is divided into a heat exchange section and a reaction section; the two ends of the heat exchange component are respectively connected to the feed pipe and the central tube.

[0009] In this invention, the heat recovery zone is used to perform a first heat exchange on the raw material passing through the feed pipe in the heat exchange component to obtain vaporized raw material; the heat exchange section and preheating zone of the heat exchange reaction zone are used to perform the first preheating and the second preheating on the vaporized raw material under external heating conditions to obtain preheated raw material; the reaction section is used to bring the preheated raw material into contact with the reforming catalyst packed in the catalyst bed from bottom to top and perform a reforming reaction to obtain reformed gas. After performing a second heat exchange with the vaporized raw material in the central tube, the reformed gas is sent to the heat recovery zone to perform the first heat exchange with the raw material in the heat exchange component to obtain product gas that is discharged through the discharge pipe.

[0010] The second aspect of the present invention provides an application of the system provided in the first aspect in the reforming of methane-rich gas into syngas, preferably in the reforming of natural gas into syngas, biogas into syngas, and coke oven gas into syngas.

[0011] A third aspect of the present invention provides a method for reforming methane-rich gas to produce syngas, the method comprising:

[0012] (1) Mix methane-rich gas with water to obtain raw material, perform first heat exchange to obtain vaporized raw material;

[0013] (2) The vaporized raw material is subjected to a first preheating and a second preheating under external heating conditions to obtain preheated raw material;

[0014] (3) The preheated raw material and the reforming catalyst are brought into contact and reformed to obtain reformed gas. After the reformed gas undergoes a second heat exchange with the vaporized raw material, the first heat exchange is performed to obtain syngas as product gas.

[0015] Preferably, the method is carried out in the system provided in the first aspect, wherein the raw material undergoes the first heat exchange in the heat recovery zone via the feed pipe, and the vaporized raw material undergoes the first preheating and the second preheating in the central pipe and the preheating zone of the heat exchange reaction zone which is heated externally, respectively. After the preheating, the raw material passes through the reaction section from bottom to top, contacts the reforming catalyst packed in the catalyst bed and undergoes the reforming reaction, and the reformed gas undergoes the second heat exchange with the vaporized raw material, then undergoes the first heat exchange, and the product gas is discharged through the discharge pipe.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The system provided by the present invention integrates the vaporization, preheating, reforming reaction and reforming gas heat recovery of raw materials into the same reaction tube. The compact design eliminates the raw material preheating unit and the reforming gas by-product steam unit, which greatly simplifies the process flow, reduces the footprint of the equipment, and facilitates skid-mounting. On the other hand, it also improves the energy utilization efficiency of the reforming reaction unit.

[0018] Meanwhile, the specific configuration of the reaction section and the heat exchange section, while ensuring that the overall diameter of the reaction tube remains unchanged, significantly reduces the heat transfer distance and improves the heat transfer efficiency and reaction efficiency.

[0019] (2) The application of the system provided by the present invention in the reforming of methane-rich gas to syngas, especially in the scenario of syngas production from biogas components, not only has low reaction thermal resistance and small radial temperature difference, but also low carbon deposition risk and high reaction efficiency, that is, it has a high methane conversion rate and a high total carbon atom utilization rate. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an integrated heat exchange-reforming reaction system provided by the present invention;

[0021] Figure 2 This is a schematic diagram of material flow and energy transfer in an integrated heat exchange-reforming reaction system provided by the present invention;

[0022] Figure 3 This is a concentration distribution diagram of each component in the reaction tube corresponding to Example 1;

[0023] Figure 4 This is a diagram showing the temperature and rate distribution inside the reaction tube corresponding to Example 1.

[0024] Explanation of reference numerals in the attached figures

[0025] I. Heat recovery zone; II. Heat exchange and recovery zone; III. Preheating zone;

[0026] a. Raw materials, b. Product gas, c. Heat recovery zone shell, d. Central tube, e. Heat exchange reaction zone shell, f. Reformed gas, g. Preheating zone shell;

[0027] 1. Feed pipe; 2. Discharge pipe; 3. Heat exchange components; 4. Connecting pipe; 5. Central pipe; 6. Feed distributor; 7. Support component; 8. Catalyst bed; 9. Connecting component; 10. Flange cover; 11. Top welded flange; 12. Shell; 13. Bottom welded head; 14. Thermocouple sheath. Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] In this invention, unless otherwise specified, "first" and "second" do not indicate a sequence or limit the various materials or steps, but are used only to distinguish or indicate that they are not the same material or step. For example, "first preheating" and "second preheating" are only used to indicate that they are not the same preheating.

[0030] In this invention, unless otherwise specified, the “top” of the container refers to 0-10% of the container’s height from top to bottom; the “upper part” of the container refers to 10-40% of the container’s height from top to bottom; the “middle part” of the container refers to 40-70% of the container’s height from top to bottom; the “lower part” of the container refers to 70-90% of the container’s height from top to bottom; and the “bottom” of the container refers to 90-100% of the container’s height from top to bottom.

[0031] The first aspect of this invention provides an integrated heat exchange-reforming reaction system, such as... Figure 1-2 As shown, the system includes at least one parallel reaction tube. The top of the reaction tube is provided with a feed pipe 1 and a discharge pipe 2. The shell 12 of the reaction tube is divided into a heat recovery zone I, a heat exchange reaction zone II, and a preheating zone III from top to bottom. The heat exchange reaction zone II and the preheating zone III are heated by external heating. The heat recovery zone I is provided with a heat exchange component 3. The heat exchange reaction zone II is provided with a catalyst bed 8 arranged in a ring around the central tube 5, and the heat exchange reaction zone II is divided into a heat exchange section and a reaction section. The two ends of the heat exchange component 3 are respectively connected to the feed pipe 1 and the central tube 5.

[0032] In this invention, raw material a undergoes a first heat exchange in the heat recovery zone I via the feed pipe 1, resulting in vaporized raw material that undergoes a first preheating and a second preheating in the heat exchange reaction zone II and preheating zone III, which are heated externally. After preheating, the raw material passes through the reaction section from bottom to top, contacts the loaded reforming catalyst, and undergoes a reforming reaction, resulting in reformed gas f. After a second heat exchange with the vaporized raw material, the first heat exchange is performed, resulting in product gas b, which is discharged through the discharge pipe 2.

[0033] In this invention, such as Figure 2 As shown, raw material a undergoes a first heat exchange in heat recovery zone I from top to bottom to obtain vaporized raw material; then it undergoes a first preheating in central tube d, with the heat for the first preheating provided by external heating from the outer shell e of the heat exchange reaction zone; then it undergoes a second preheating in preheating zone III, with the heat for the second preheating provided by external heating from the outer shell g of the preheating zone. After preheating, the raw material, from bottom to top, comes into contact with the packed reforming catalyst in the annular area (i.e., the reaction section) formed by the outer diameter of central tube d and the inner wall of heat exchange reaction zone II and undergoes a reforming reaction to obtain reformed gas f. After a second heat exchange with the vaporized raw material in central tube d, it undergoes a first heat exchange with the raw material in heat exchange component 3 inside the outer shell c of the heat recovery zone to obtain product gas b.

[0034] In this invention, unless otherwise specified, such as Figure 2 As shown, the outer shells of the heat recovery zone (c), the heat exchange reaction zone (e), and the preheating zone (g) are all made of high-temperature resistant thermally conductive metal materials, including but not limited to high-nickel alloy materials.

[0035] In this invention, the entire outer shell of the reaction tube is made of high-temperature resistant metal thermally conductive material. After the reaction tube is inserted into the conversion furnace, the height of the heat recovery zone is inside the insulation material of the conversion furnace, while the heat exchange reaction zone and the preheating zone are inside the furnace chamber.

[0036] In this invention, unless otherwise specified, the preheated raw material passes through the reaction section from bottom to top, contacts the packed reforming catalyst and undergoes a reforming reaction, and the resulting reformed gas also undergoes a second heat exchange with the vaporized raw material from bottom to top, and then undergoes a first heat exchange with the raw material to obtain the product gas discharged.

[0037] In this invention, unless otherwise specified, the externally heated heat exchange reaction zone II and preheating zone III refer to the external heat being transferred to heat exchange reaction zone II and preheating zone III respectively through the outer shell e of the heat exchange reaction zone and the outer shell g of the preheating zone, thereby achieving the first and second preheating of the vaporized raw materials. In this invention, the system consists of at least one parallel reaction tube, such as... Figure 1 As shown, the system consists of a reaction tube.

[0038] In this invention, preferably, the height-to-diameter ratio of the reaction tube is 15-30, for example, 15, 18, 20, 22, 25, 28, 30, or any value within the range of any two values, wherein the height-to-diameter ratio is the ratio of the height to the inner diameter of the reaction tube. In this invention, the inner diameter of the reaction tube is 80-150 mm, for example, 80 mm, 100 mm, 120 mm, 150 mm, or any value within the range of any two values.

[0039] In this invention, preferably, as follows: Figure 1 As shown, the height ratio of the heat recovery zone I, the heat exchange reaction zone II, and the preheating zone III is 13-25:68-75:4-17.

[0040] In this invention, the reforming reaction is an endothermic reaction, requiring the provision of heat. Preferably, the external heating method is selected from at least one of combustion furnace heating, electric heating, and electromagnetic induction heating.

[0041] In this invention, such as Figure 1 As shown, the fact that the two ends of the heat exchange component 3 are respectively connected to the feed pipe 1 and the central pipe 5 means that, according to the material flow direction, the inlet end of the heat exchange component 3 is connected to the feed pipe 1, and the outlet end is connected to the central pipe 5.

[0042] In this invention, such as Figure 1 As shown, preferably, the heat exchange component 3 is selected from wound heat exchange tubes, spiral heat exchange tubes, coiled heat exchange tubes, finned heat exchange tubes, and microchannel heat exchange tubes; more preferably, the heat exchange component is a coiled heat exchange tube with a coil number of not less than 15 turns, so that the raw material passes through the first heat exchange in the heat exchange component 3 to obtain vaporized raw material.

[0043] In this invention, such as Figure 1 As shown, preferably, the heat recovery zone I is further provided with a receiving pipe 4, the two ends of which are connected to the heat exchange component 3 and the central pipe 5, respectively. That is, the inlet end of the receiving pipe 4 is connected to the heat exchange component 3, and the outlet end is connected to the central pipe 5.

[0044] In this invention, such as Figure 1 As shown, preferably, the receiving pipe 4 is positioned after or before the heat exchange component 3, according to the material flow direction, and more preferably after. This arrangement is more conducive to gas phase preheating and liquid phase vaporization of the raw material.

[0045] In this invention, such as Figure 1 As shown, preferably, the receiving pipe 4 and the heat exchange component 3 are connected by a connector 9.

[0046] In this invention, such as Figure 1 As shown, preferably, the inner diameter of the heat exchange component 3 is less than or equal to the inner diameter of the receiving pipe 4 and less than or equal to the inner diameter of the central pipe 5;

[0047] In this invention, such as Figure 1 As shown, more preferably, the inner diameter ratio of the heat exchange component 3, the receiving pipe 4, and the central pipe 5 is 1:1.2-3:3-7.5. This arrangement helps to control the gas velocity of the vaporized raw material and avoids excessively high gas velocity from affecting the heat exchange effect.

[0048] In this invention, such as Figure 1 As shown, preferably, the heat exchange section is the area formed by the inner diameter of the central tube 5; the reaction section is the annular area formed by the outer diameter of the central tube 5 and the inner wall of the heat exchange reaction zone II. This arrangement allows the reforming reaction to occur within the annular gap between the shell of the heat exchange reaction zone and the central tube, resulting in low reaction thermal resistance, small radial temperature difference, low risk of carbon buildup, and high reaction efficiency; it also avoids the use of high-temperature waste heat recovery devices, resulting in a small reaction system size, small footprint, and ease of skid-mounting.

[0049] In this invention, such as Figure 1 As shown, the reaction section is provided with a catalyst bed 8 filled with reforming catalyst. Preferably, the height of the catalyst bed is equal to the height of the heat exchange reaction zone II.

[0050] In this invention, preferably, the reforming catalyst comprises a first active component and a first auxiliary agent, wherein the first active component is selected from nickel, and the first auxiliary agent is selected from at least one of lithium, sodium, potassium, magnesium, calcium, copper, cerium, and zinc. In this invention, the reforming catalyst further comprises a support, which includes, but is not limited to, alumina.

[0051] In this invention, preferably, based on the total weight of the reforming catalyst, the content of the first active component is 10-20 wt%, for example, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, or any value within the range of any two values; the content of the first auxiliary agent is 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any value within the range of any two values.

[0052] In this invention, such as Figure 1 As shown, preferably, the inner diameter ratio of the central tube 5 and the shell 12 is 0.4-0.6:1, for example, 0.4:1, 0.5:1, 0.6:1, and any value within the range of any two values.

[0053] In this invention, such as Figure 1 As shown, preferably, the central tube 5 is further provided with a first preconversion layer filled with a first preconversion catalyst; more preferably, the height ratio of the first preconversion layer to the central tube 5 is 0.1-0.5:1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, and any value in any range of any two values.

[0054] In this invention, such as Figure 1 As shown, preferably, the preheating zone III is provided with a second preconversion layer filled with a second preconversion catalyst; more preferably, the height ratio of the second preconversion layer to the preheating zone III is 0.1-1:1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 1:1, and any value within the range of any two values.

[0055] In this invention, such as Figure 1 As shown, if a first pre-conversion layer is provided inside the central tube 5, then a second pre-conversion layer must be provided in the preheating zone III, and the height ratio of the second pre-conversion layer to that of the preheating zone III is 1:1. That is to say, only if the height of the second pre-conversion layer is equal to the height of the preheating zone III is it considered that a first pre-conversion layer is provided in the central tube 5; otherwise, only a second pre-conversion layer with a lower height than that in the preheating zone III is considered.

[0056] In this invention, the first preconversion catalyst and the second preconversion catalyst may be the same or different, but preferably the same.

[0057] In this invention, the first pre-conversion catalyst and the second pre-conversion catalyst each independently include: a second active component and a second auxiliary agent; wherein the second active component is selected from nickel, and the second auxiliary agent is selected from at least one of lithium, sodium, potassium, magnesium, calcium, copper, cerium, and zinc. In this invention, the first and second pre-conversion catalysts also include a support, which includes, but is not limited to, alumina.

[0058] In this invention, the content of the second active component is 25-40 wt%, for example, 25 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, or any value within the range of any two values, based independently on the total weight of the first preconversion catalyst and the second preconversion catalyst; the content of the second auxiliary agent is 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any value within the range of any two values.

[0059] In this invention, such as Figure 1 As shown, preferably, the preheating zone III is equipped with a feed distributor 6 connected to the central tube 5. In this invention, the feed distributor 6 serves two purposes: firstly, to support the catalyst bed 8, and secondly, to uniformly distribute the preheated raw materials.

[0060] In this invention, such as Figure 1 As shown, preferably, the preheating zone III is further provided with a support member 7 connected to the feed distributor 6.

[0061] In this invention, such as Figure 1 As shown, preferably, the top of the housing 12 is provided with a flange cover 10 connected by a top welding flange 11, and the bottom is provided with a bottom welding head 13; more preferably, the flange cover 10 is provided with the feed pipe 1 and the discharge pipe 2.

[0062] In this invention, it is sufficient that the feed pipe 1 is connected to the heat exchange component 3. For example... Figure 1 As shown, the feed pipe 1 can also extend to the heat recovery zone I and connect with the heat exchange component 3, so that the raw material enters the heat exchange component 3 through the feed pipe 1 in sequence to carry out the first heat exchange in the heat recovery zone I.

[0063] In this invention, such as Figure 1As shown, preferably, at least one thermocouple sleeve 14 is also provided on the flange cover 10; more preferably, the bottom of at least one of the thermocouple sleeves 14 extends above the reaction section for detecting the outlet temperature of the catalyst bed, that is, the temperature of the reformed gas exiting the heat recovery zone II.

[0064] In this invention, such as Figure 1 As shown, more preferably, the bottom of at least one of the thermocouple sheaths 14 extends above the heat recovery zone I for detecting the temperature of the product gas b.

[0065] The second aspect of the present invention provides an application of the system provided in the first aspect in the reforming of methane-rich gas into syngas, preferably in the reforming of natural gas into syngas, biogas into syngas, and coke oven gas into syngas.

[0066] A third aspect of the present invention provides a method for reforming methane-rich gas to produce syngas, the method comprising:

[0067] (1) Mix methane-rich gas with water to obtain raw material, perform first heat exchange to obtain vaporized raw material;

[0068] (2) The vaporized raw material is subjected to a first preheating and a second preheating under external heating conditions to obtain preheated raw material;

[0069] (3) The preheated raw material and the reforming catalyst are brought into contact and reformed to obtain reformed gas. After the reformed gas undergoes a second heat exchange with the vaporized raw material, the first heat exchange is performed to obtain syngas as product gas.

[0070] In this invention, preferably, in step (1), the molar ratio of H2O to CH4 in the raw materials is 1.5-3.5, for example, 1.5, 1.8, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.8, 3, 3.2, 3.5, and any value within the range of any two values, preferably 2-3, more preferably 2.1-2.5.

[0071] In this invention, preferably, the CH4 content in the methane-rich gas is 45-70 mol%, for example, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, or any value within any range of two such values; the sulfur content is ≤0.5 mg / Nm³. 3 For example, 0.5 mg / Nm 3 0.4 mg / Nm 3 0.3 mg / Nm 3 0.2 mg / Nm 3 0.1 mg / Nm 30.01 mg / Nm 3 And any value within a range consisting of any two values; chlorine content ≤ 0.1 mg / Nm 3 For example, 0.1 mg / Nm 3 0.08 mg / Nm 3 0.06 mg / Nm 3 0.05 mg / Nm 3 0.02 mg / Nm 3 0.01 mg / Nm 3 , and any value within a range consisting of any two values.

[0072] In this invention, the content parameters of each component in the methane-rich gas were measured using the methods of GB / T 13610-2020, GB / T11060.5-2010 and DB43 / T 2306-2022.

[0073] In this invention, the sulfur and chlorine content and other poison content in the methane-rich gas meet the technical requirements of the reforming catalyst; otherwise, the methane-rich gas is pretreated to meet the above requirements.

[0074] In this invention, preferably, the molar ratio of CH4 to CO2 in the methane-rich gas is 1:0.1-2, for example, 1:0.1, 1:0.2, 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, or any value within any range of two such values, preferably 1:0.4-1.5. This setting helps to increase the proportion of effective gas in the product synthesis gas, thereby improving the total carbon atom utilization rate of the raw materials.

[0075] In this invention, a wide range of types of methane-rich gas can be selected, as long as the above-mentioned limitations are met. Preferably, the methane-rich gas is selected from at least one of natural gas, biogas, and coke oven gas.

[0076] In this invention, in step (1), the water includes, but is not limited to, desalinated water, deionized water, etc.

[0077] In this invention, the first heat exchange is intended to heat the methane-rich gas and vaporize the water to obtain a vaporized feedstock. Preferably, the vaporization rate of water in the vaporized feedstock is ≥50%, for example, 50%, 60%, 80%, 90%, 100%, or any value within a range of any two of these values, preferably 80-100%.

[0078] In this invention, the vaporization rate parameter is obtained by heat transfer and gas-liquid balance simulation calculation.

[0079] In this invention, preferably, the temperature of the vaporized raw material is 180-450℃, for example, 180℃, 200℃, 300℃, 330℃, 350℃, 380℃, 400℃, 430℃, and any value in any range of any two values, preferably 330-430℃.

[0080] In this invention, the first preheating and the second preheating are intended to bring the temperature of the vaporized raw material to the inlet temperature of the reforming reaction. Preferably, in step (2), the temperature of the preheated raw material is 400-650°C, for example, 400°C, 420°C, 450°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 580°C, 600°C, 620°C, 650°C, and any value within the range of any two values, preferably 450-600°C, more preferably 500-550°C.

[0081] In this invention, the temperature of the preheated raw material is equivalent to... Figure 1 The inlet temperature of catalyst bed 8.

[0082] In this invention, the heat for both the first and second preheating is provided by external heating, as long as the temperature of the preheated raw material meets the above-mentioned limitations. Preferably, the temperature provided by the external heating is 800-1200℃, for example, 800℃, 900℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, and any value within any range of any two values.

[0083] In this invention, preferably, the external heating method is selected from at least one of combustion furnace heating, electric heating and electromagnetic induction heating.

[0084] In this invention, such as Figure 1 As shown, the temperature of the reforming reaction is generally expressed by the range of the inlet temperature and the outlet temperature of the catalyst bed 8; wherein, the inlet temperature of the catalyst bed 8 is equivalent to the temperature of the feed after preheating; and the outlet temperature of the catalyst bed 8 is equivalent to the temperature of the reformed gas after the second heat exchange.

[0085] In this invention, preferably, in step (3), the conditions for the reforming reaction include: a temperature of 400-980℃, for example, 400℃, 420℃, 450℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 580℃, 600℃, 620℃, 650℃, 680℃, 700℃, 750℃, 800℃, 850℃, 900℃, 920℃, 940℃, 950℃, 980℃, and any value within any range of any two values, preferably 450-980℃, more preferably 500-950℃, and even more preferably 550-940℃.

[0086] In this invention, preferably, in step (3), the conditions for the reforming reaction further include: a pressure of 0.5-2.5 MPa, for example, 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.5 MPa, and any value within the range of any two values, preferably 0.8-2 MPa, more preferably 1-1.5 MPa.

[0087] In this invention, all pressure parameters refer to gauge pressure.

[0088] In this invention, preferably, in step (3), the conditions for the reforming reaction further include: the volume hourly space velocity (VHSV) of the preheated feedstock, calculated as CH4, is 500-2000 h⁻¹. -1 For example, 500h -1 600h -1 800h -1 900h -1 1000h -1 1100h -1 1200h -1 1300h -1 1500h -1 1800h -1 2000h -1 And any value within the range of any two values, preferably 800-1500h. -1 More preferably 1000-1300h -1 .

[0089] In this invention, the volumetric space velocity parameter is a value under standard conditions.

[0090] In this invention, the second heat exchange is intended to provide the heat of the reformed gas to the vaporized feedstock. Preferably, the temperature of the reformed gas after the second heat exchange is 900-980°C, for example, 900°C, 920°C, 930°C, 940°C, 950°C, 960°C, 980°C, or any value within a range of any two of these values, preferably 900-950°C, and more preferably 920-940°C.

[0091] In this invention, the first heat exchange aims to further recover and utilize the heat of the reformed gas, that is, to convert the raw material into a vaporized raw material, and to convert the reformed gas after the second heat exchange into syngas. Preferably, the temperature of the syngas is 300-400℃, for example, 300℃, 320℃, 330℃, 340℃, 350℃, 380℃, 400℃, and any value within any range of any two of these values, preferably 320-350℃.

[0092] In this invention, preferably, the CH4 content in the synthesis gas is ≤3.5 mol%, for example, 3.5 mol%, 3 mol%, 2.5 mol%, 2.2 mol%, 1.5 mol%, 1 mol%, 0.8 mol%, 0.7 mol%, 0.6 mol%, 0.5 mol%, 0.4 mol%, 0.3 mol%, 0.2 mol%, 0.1 mol%, 0.05 mol%, 0.01 mol%, and any value within any range of any two values, further preferably ≤2.5 mol%, more preferably ≤1 mol%, and most preferably ≤0.7 mol%.

[0093] In this invention, preferably, in step (3), the reforming catalyst comprises a first active component and a first auxiliary agent, wherein the first active component is selected from nickel, and the first auxiliary agent is selected from at least one of lithium, sodium, potassium, magnesium, calcium, copper, cerium, and zinc. In this invention, the reforming catalyst further comprises a support, which includes, but is not limited to, alumina.

[0094] In this invention, preferably, based on the total weight of the reforming catalyst, the content of the first active component is 10-20 wt%, for example, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, or any value within the range of any two values; the content of the first auxiliary agent is 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any value within the range of any two values.

[0095] In this invention, preferably, the method further includes: under external heating conditions, subjecting the vaporized raw material to the first preheating, and after contacting with the first preconversion catalyst and undergoing the first preconversion, subjecting it to the second preheating, and after contacting with the second preconversion catalyst and undergoing the second preconversion, to obtain the preheated raw material.

[0096] In this invention, the first preconversion catalyst and the second preconversion catalyst may be the same or different, but preferably the same.

[0097] In this invention, preferably, the first pre-conversion catalyst and the second pre-conversion catalyst each independently comprise: a second active component and a second auxiliary agent; wherein the second active component is selected from nickel, and the second auxiliary agent is selected from at least one of lithium, sodium, potassium, magnesium, calcium, copper, cerium, and zinc. In this invention, the first and second pre-conversion catalysts also include a support, which includes, but is not limited to, alumina.

[0098] In this invention, the content of the second active component is 25-40 wt%, for example, 25 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, or any value within the range of any two values, based independently on the total weight of the first preconversion catalyst and the second preconversion catalyst; the content of the second auxiliary agent is 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any value within the range of any two values.

[0099] In this invention, unless otherwise specified, the first pre-conversion and the first preheating are performed simultaneously; similarly, the second pre-conversion and the second preheating are also performed simultaneously.

[0100] In this invention, if a first pre-conversion is performed, a second pre-conversion is necessarily performed; if a second pre-conversion is performed, the first pre-conversion may or may not be performed. This mainly depends on the height ratio of the second pre-conversion layer to the preheating zone in the preheating zone, and the height ratio of the first pre-conversion layer to the central tube in the central tube.

[0101] In this invention, preferably, the method is carried out in the system provided in the first aspect, wherein the raw material undergoes the first heat exchange in the heat recovery zone I via the feed pipe 1, and the vaporized raw material undergoes the first preheating and the second preheating in the heat exchange reaction zone II and the preheating zone III, which are heated by external sources, respectively. After the preheating, the raw material passes through the reaction section from bottom to top, contacts the reforming catalyst packed in the catalyst bed 8, and undergoes the reforming reaction. After the reformed gas undergoes the second heat exchange with the vaporized raw material, the first heat exchange is performed, and the product gas is discharged through the discharge pipe 2.

[0102] The method provided by this invention has a high methane conversion rate, that is, a methane conversion rate ≥85%, for example, 85%, 88%, 90%, 92%, 95%, 97%, 98%, 99%, 100%, and any value in any range of any two values, preferably ≥95%.

[0103] Using the method provided by this invention, the composition of the syngas product satisfies: It has a high total carbon atom utilization rate, that is, a total carbon atom utilization rate ≥68%, for example, 68%, 70%, 72%, 75%, 77%, 78%, 80%, 85%, 90%, 92%, 95%, 100%, and any value in any range of any two values, preferably ≥75%.

[0104] The present invention will be described in detail below through embodiments.

[0105] Reforming catalyst A1 comprises an alumina support, 15 wt% nickel, and 1.5 wt% zinc;

[0106] The pre-conversion catalyst A2 comprises an alumina support, 35 wt% nickel, and 2.5 wt% zinc.

[0107] The methane conversion rate is calculated using the following formula:

[0108]

[0109] According to the composition of syngas products, the following conditions must be met: The percentage of available carbon (CO2+CO) in the qualified product gas is calculated to obtain the total carbon atom utilization rate; the total carbon atom utilization rate is calculated using the following formula:

[0110]

[0111] Example 1

[0112] System such as Figure 1As shown, the system consists of a reaction tube. The shell of the reaction tube is divided into three interconnected zones from top to bottom: a heat recovery zone I, a heat exchange reaction zone II, and a preheating zone III. The heat exchange reaction zone II and the preheating zone III are heated externally. The heat recovery zone I is provided with a heat exchange component 3 and a receiving pipe 4 connected in sequence, and the heat exchange component 3 and the receiving pipe 4 are connected by a connector 9. The heat exchange reaction zone II is provided with a catalyst bed 8 arranged in a ring around the central pipe 5, and the heat exchange reaction zone II is divided into a heat exchange section and a reaction section. The two ends of the heat exchange component 3 are connected to the feed pipe 1 and the central pipe 5. The preheating zone III is provided with a feed distributor 6 and a support component 7. The top of the shell 12 is provided with a flange cover 10, and the flange cover 10 is provided with two thermocouple sleeves 14, a feed pipe 1, and a discharge pipe 2. The bottom of one thermocouple sleeve 14 extends to the top of the reaction section, and the bottom of the other thermocouple sleeve 14 extends to the top of the heat recovery zone I.

[0113] The height-to-diameter ratio of the reaction tube is 25.2, and the inner diameter is 96 mm. The height ratio of the heat recovery zone I, the heat exchange reaction zone II, and the preheating zone III is 22:74:4. The inner diameter ratio of the heat exchange component 3, the receiving pipe 4, and the central pipe 5 is 1:1.25:3.13. The inner diameter ratio of the central pipe 5 and the shell 12 is 0.52:1.

[0114] The method is performed in the above system and includes the following steps:

[0115] (1) Mix biogas and desalinated water to obtain raw material. Perform the first heat exchange to obtain vaporized raw material at a temperature of 430℃;

[0116] The biogas contained 60 mol% CH4 and 0.1 mg / Nm³ of sulfur. 3 The chlorine content is 0.1 mg / Nm³. 3 The molar ratio of CH4 to CO2 is 6:4; the molar ratio of H2O to CH4 in the above raw materials is 2.1:1; the vaporization rate of water in the above vaporization raw materials is 100%.

[0117] (2) Combustion heating is adopted, and the furnace temperature is 1050℃. The above-mentioned vaporized raw materials are preheated in the first and second preheating in sequence to obtain preheated raw materials at a temperature of 530℃.

[0118] (3) The preheated raw material and reforming catalyst A1 are brought into contact and reformed to obtain reformed gas. The reformed gas is then subjected to a second heat exchange with the vaporized raw material to obtain a second heat exchange at a temperature of 936°C. The reformed gas is then subjected to the first heat exchange to obtain syngas P1 at a temperature of 330°C with a methane content of 0.49 mol.

[0119] The reforming reaction was carried out at a temperature of 530-936℃ and a pressure of 1 MPa. The volume hourly space velocity (VHSV) of the preheated feedstock, calculated as CH4, was 1100 h⁻¹.-1 .

[0120] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software. Based on this geometric model, a heterogeneous reactor model was constructed that couples the particle and bed dimensions. The physical field settings included:

[0121] S1. The physical field of "concentrated mass transfer in a packed bed" is used to describe the reaction-transfer coupling at the particle and bed scales on the reaction side. The molar composition of the reaction side inlet is set as the bed-scale boundary condition. At the particle scale, the gas film mass transfer resistance between the outer surface of the particle and the bulk gas phase is considered. The Sherwood number is estimated by using the Frossling number expression, and then the mass transfer coefficient within the gas film is obtained.

[0122] S2. Two "chemical" physical fields are used to describe the reaction kinetics at the catalyst particle scale and bed scale respectively, and the component partial pressures at different locations within the particles and the bed are correlated respectively.

[0123] S3. The "Brinkman equation" is used to describe the fluid flow on the heat exchange side and the fluid flow in the porous medium on the reaction side; the mass flow rate of the fluid on both sides is set as the inlet boundary condition, and the pressure is set as the outlet boundary condition.

[0124] S4. "Packed bed heat transfer" is used to describe heat transfer at the particle and bed scale. To simplify calculations, the temperature difference between the bulk gas phase and the outer surface of the particles is ignored, and the catalyst particles are assumed to be isothermal. The inlet temperatures of the two side streams are set as inlet boundary conditions, assuming a constant furnace temperature. The boundary conditions between the outer tube wall and the furnace are set as "convective heat flux," with a given heat transfer coefficient value, considering contributions from both convective and radiative heat transfer. A "thin-layer thermal resistance" is introduced between the bed and the tube wall to represent the influence of the stagnant layer on heat transfer. The stagnant layer thermal resistance is expressed as the reciprocal of the specific heat transfer coefficient and estimated using the correlation proposed by De Wasch and Froment.

[0125] The concentration distribution of each component in the reaction tube was obtained through simulation calculations, as follows: Figure 3 As shown, the temperature and velocity distributions inside the reaction tube are as follows: Figure 4 As shown in Table 1, the methane outlet conversion rate was calculated based on the methane concentration distribution at the reaction tube outlet; the average temperatures at the catalyst bed inlet and outlet are also shown in Table 1.

[0126] Example 2

[0127] The system provided according to Example 1;

[0128] The method provided in Example 1 is different,

[0129] In step (1), the temperature of the vaporized feedstock is 400℃;

[0130] In step (2), the temperature of the preheated raw material is 511℃;

[0131] In step (3), the temperature of the reforming reaction is 511-934℃; the volume hourly space velocity (VHSV) of the preheated feedstock, calculated as CH4, is 1200 h⁻¹. -1 The temperature of the reformed gas after the second heat exchange is 934℃.

[0132] Under the same conditions, syngas P2 was obtained at a temperature of 326℃ with a methane content of 0.53 mol%.

[0133] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0134] Example 3

[0135] The system provided according to Example 1;

[0136] The method provided in Example 1 is different,

[0137] In step (1), the temperature of the vaporized feedstock is 340℃;

[0138] In step (2), the temperature of the preheated raw material is 492℃;

[0139] In step (3), the temperature of the reforming reaction is 492-932℃; the volume hourly space velocity (VHSV) of the preheated feedstock, calculated as CH4, is 1500 h⁻¹. -1 The temperature of the reformed gas after the second heat exchange is 932℃.

[0140] Under the same conditions, syngas P3 was obtained at a temperature of 324℃ with a methane content of 0.54 mol%.

[0141] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0142] Example 4

[0143] The system provided according to Example 1;

[0144] The method provided in Example 1 is different,

[0145] In step (1), the molar ratio of H2O to CH4 in the above raw materials is 2.5:1;

[0146] In step (2), the temperature of the preheated raw material is 486℃;

[0147] In step (3), the temperature of the reforming reaction is 486-929℃; the temperature of the reformed gas after the second heat exchange is 929℃.

[0148] Under the same conditions, syngas P4 was obtained at a temperature of 320℃ with a methane content of 0.36 mol%.

[0149] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0150] Example 5

[0151] The system provided according to Example 1;

[0152] The method provided in Example 1 is different,

[0153] In step (1), the molar ratio of H2O to CH4 in the above raw materials is 3.5:1; the temperature of the above vaporization raw materials is replaced with 175℃, and the vaporization rate of water is 52.1%;

[0154] In step (2), the furnace temperature is replaced with 1000℃; the temperature of the raw material after preheating is 473℃;

[0155] In step (3), the temperature of the reforming reaction is 473-860℃, the pressure is 2.5MPa, and the volume hourly space velocity (VHSV) of the preheated feedstock, calculated as CH4, is 800 h⁻¹. -1 The temperature of the reformed gas after the second heat exchange is 860℃.

[0156] Under the same conditions, syngas P5 was obtained at a temperature of 315℃ with a methane content of 2.12 mol%.

[0157] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0158] Example 6

[0159] The system provided according to Example 1;

[0160] The method provided in Example 1 is different,

[0161] In step (1), the molar ratio of CH4 to CO2 in the above-mentioned biogas is 7:3; the molar ratio of H2O to CH4 in the above-mentioned raw materials is 2:1; and the temperature of the above-mentioned vaporized raw materials is 380℃.

[0162] In step (2), the furnace temperature is replaced with 1000℃; the temperature of the raw material after preheating is 521℃;

[0163] In step (3), the temperature of the reforming reaction is 521-885℃, and the temperature of the reformed gas after the second heat exchange is 885℃.

[0164] Under the same conditions, syngas P6 was obtained at a temperature of 303℃ with a methane content of 0.63 mol%.

[0165] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0166] Example 7

[0167] The system according to Example 1 differs in that,

[0168] The central tube 5 is filled with pre-conversion catalyst A2, and the height ratio of the first pre-conversion layer to the central tube 5 is 0.1:1;

[0169] Preheating zone III is filled with preconversion catalyst A2, and the height ratio of the second preconversion layer to preheating zone III is 1:1;

[0170] The method provided in Example 1 differs from the method described above in that it is performed within the aforementioned system.

[0171] In step (1), the temperature of the above vaporized raw material is 433°C, and the vaporization rate of water is 100%.

[0172] In step (2), the temperature of the preheated raw material is 526°C;

[0173] In step (3), the temperature of the above reforming reaction is 526-938℃, and the temperature of the reformed gas after the second heat exchange is 938℃;

[0174] Under the same conditions, syngas P7 was obtained at a temperature of 332℃ with a methane content of 0.33 mol%.

[0175] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0176] Example 8

[0177] The system provided in Example 1 differs in that,

[0178] The height ratio of heat recovery zone I, heat exchange reaction zone II, and preheating zone III is 10:85:5.

[0179] The method provided in Example 1 differs from the method described above in that it is performed within the aforementioned system.

[0180] In step (1), the temperature of the above vaporized raw material is 148°C, and the vaporization rate of water is 75%.

[0181] In step (2), the temperature of the preheated raw material is 380°C;

[0182] In step (3), the temperature of the reforming reaction is 380-800℃; the temperature of the reformed gas after the second heat exchange is 800℃.

[0183] Under the same conditions, syngas P8 was obtained at a temperature of 400℃ with a methane content of 3.45 mol%.

[0184] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0185] Example 9

[0186] The system provided in Example 1 differs in that,

[0187] The ratio of the inner diameter of the central tube 5 to that of the shell 12 is 0.3:1.

[0188] The method provided in Example 1 differs from the method described above in that it is performed within the aforementioned system.

[0189] In step (1), the temperature of the above vaporized raw material is 156°C, and the vaporization rate of water is 100%.

[0190] In step (2), the temperature of the preheated raw material is 410°C;

[0191] In step (3), the temperature of the reforming reaction is 410-860℃; the temperature of the reformed gas after the second heat exchange is 860℃.

[0192] Under the same conditions, syngas P9 was obtained at a temperature of 300℃ with a methane content of 3.31 mol%.

[0193] A geometric model of the reaction tube was established using COMSOL Multiphysics 6.2 software, with the same physical field settings as in Example 1. The methane conversion rate at the reaction tube outlet and the average temperatures at the catalyst bed inlet and outlet are shown in Table 1.

[0194] Comparative Example 1

[0195] A tubular fixed-bed conversion reactor without internal heat exchange components is adopted.

[0196] The height-to-diameter ratio of the reaction tube is 13.8, and the inner diameter is 96 mm.

[0197] The method is performed in the above system and includes the following steps:

[0198] Biogas and demineralized water are mixed, and the raw material enters from the top of the reactor and passes through the catalyst bed from top to bottom. It comes into contact with the reforming catalyst A1 and undergoes a reforming reaction before being discharged, resulting in syngas DP1 with a temperature of 880°C and a methane content of 2.78 mol%.

[0199] The biogas contained 60 mol% CH4 and 0.1 mg / Nm³ of sulfur. 3 The chlorine content is 0.1 mg / Nm³. 3 The molar ratio of CH4 to CO2 is 6:4; the molar ratio of H2O to CH4 in the above raw materials is 2.1:1.

[0200] Combustion heating is used, with a furnace temperature of 1050℃; the reforming reaction temperature is 500-880℃; the pressure is 1 MPa; and the volume hourly space velocity (VHSV) of the preheated feedstock (calculated as CH4) is 1100 h⁻¹. -1 .

[0201] Table 1

[0202]

[0203] Note: * - Volume hourly space velocity (VHSV) of the preheated feedstock described above, expressed as CH4, in h. -1 .

[0204] Continued from Table 1

[0205]

[0206]

[0207] As can be seen from the results in Table 1, compared with Comparative Example 1, Examples 1-9 using the method provided by this invention have higher methane conversion rate and total carbon atom utilization rate. Furthermore, the feed gas undergoes direct heat exchange and vaporization within the reaction tube, resulting in a more compact structure and lower product gas exit temperature from the reaction tube. This simplifies the subsequent waste heat recovery system and makes it more suitable for distributed skid-mounted applications such as biogas conversion.

[0208] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An integrated heat exchange-reforming reaction system, characterized in that, The system includes at least one parallel reaction tube, with a feed pipe (1) and a discharge pipe (2) at the top of the reaction tube. The shell (12) of the reaction tube is divided into a heat recovery zone (I), a heat exchange reaction zone (II), and a preheating zone (III) from top to bottom. The heat exchange reaction zone (II) and the preheating zone (III) are heated by external heating. The heat recovery zone (I) is equipped with a heat exchange component (3). The heat exchange reaction zone (II) is provided with a catalyst bed (8) arranged in a ring around the central tube (5), and the heat exchange reaction zone (II) is divided into a heat exchange section and a reaction section; the two ends of the heat exchange component (3) are respectively connected to the feed pipe (1) and the central tube (5).

2. The system according to claim 1, wherein, The height-to-diameter ratio of the reaction tube is 15-30, where the height-to-diameter ratio is the ratio of the height to the inner diameter of the reaction tube. And / or, the height ratio of the heat recovery zone (I), the heat exchange reaction zone (II), and the preheating zone (III) is 13-25:68-75:4-17; And / or, the external heating method is selected from at least one of combustion furnace heating, electric heating and electromagnetic induction heating; And / or, the heat exchange component (3) is selected from wound heat exchange tubes, spiral heat exchange tubes, coil heat exchange tubes, finned heat exchange tubes, and microchannel heat exchange tubes. And / or, the heat recovery zone (I) is also provided with a receiving pipe (4), the two ends of which are respectively connected to the heat exchange component (3) and the central pipe (5).

3. The system according to claim 2, wherein, According to the material flow direction, the receiving pipe (4) is arranged after or before the heat exchange component (3), preferably after; And / or, the receiving pipe (4) and the heat exchange component (3) are connected by a connector (9); And / or, the inner diameter of the heat exchange component (3) is less than or equal to the inner diameter of the receiving pipe (4) and less than or equal to the inner diameter of the central pipe (5); And / or, the inner diameter ratio of the heat exchange component (3), the receiving pipe (4) and the central pipe (5) is 1:1.2-3:3-7.

5.

4. The system according to any one of claims 1-3, wherein, The heat exchange section is the area formed by the inner diameter of the central tube (5); the reaction section is the annular area formed by the outer diameter of the central tube (5) and the inner wall of the heat exchange reaction zone (II); And / or, the inner diameter ratio of the central tube (5) and the shell (12) is 0.4-0.6:1; And / or, the central tube (5) is provided with a first preconversion layer filled with a first preconversion catalyst; Preferably, the height ratio of the first pre-conversion layer to the central tube (5) is 0.1-0.5:1; Preferably, the preheating zone (III) is provided with a second preconversion layer filled with a second preconversion catalyst; Preferably, the height ratio of the second preconversion layer to the preheating zone (III) is 0.1-1:

1.

5. The system according to any one of claims 1-4, wherein, The preheating zone (III) is equipped with a feed distributor (6) connected to the central tube (5); Preferably, the preheating zone (III) is further provided with a support member (7) for connecting the feed distributor (6); And / or, the top of the housing (12) is provided with a flange cover (10) connected by a top welded flange (11), and the bottom is provided with a bottom welded end cap (13); Preferably, the flange cover (10) is provided with the feed pipe (1) and the discharge pipe (2); Preferably, at least one thermocouple sleeve (14) is also provided on the flange cover (10); More preferably, the bottom of at least one of the thermocouple sleeves (14) extends above the reaction section; More preferably, the bottom of at least one of the thermocouple sheaths (14) extends above the heat recovery zone (I).

6. The application of the system according to any one of claims 1-5 in the reforming of methane-rich gas into syngas, preferably in the reforming of natural gas into syngas, biogas into syngas, and coke oven gas into syngas.

7. A method for reforming methane-rich gas to produce syngas, characterized in that, The method includes: (1) Mix methane-rich gas with water to obtain raw material. Perform the first heat exchange to obtain vaporized raw material. (2) The vaporized raw material is subjected to a first preheating and a second preheating under external heating conditions to obtain preheated raw material; (3) The preheated raw material and the reforming catalyst are brought into contact and reformed to obtain reformed gas. After the reformed gas undergoes a second heat exchange with the vaporized raw material, the first heat exchange is performed to obtain syngas as product gas.

8. The method according to claim 7, wherein, In step (1), In the raw materials, the molar ratio of H2O to CH4 is 1.5-3.5, preferably 2-3, and more preferably 2.1-2.5; And / or, in the methane-rich gas, the CH4 content is 45-70 mol%, and the sulfur content is ≤0.5 mg / Nm³. 3 Chlorine content ≤0.1mg / Nm 3 ; And / or, in the methane-rich gas, the molar ratio of CH4 to CO2 is 1:0.1-2, preferably 1:0.4-1.5; And / or, the methane-rich gas is selected from at least one of natural gas, biogas, and coke oven gas; And / or, in the vaporized feedstock, the vaporization rate of water is ≥50%, preferably 80-100%; And / or, the temperature of the vaporized raw material is 180-450℃, preferably 330-430℃.

9. The method according to claim 7 or 8, wherein, In step (2), The temperature of the preheated raw material is 400-650℃, preferably 450-600℃, and more preferably 500-550℃; And / or, the temperature provided by the external heating is 800-1200°C; And / or, the external heating method is selected from at least one of combustion furnace heating, electric heating and electromagnetic induction heating.

10. The method according to any one of claims 7-9, wherein, In step (3), The conditions for the reforming reaction include: a temperature of 400-980℃, preferably 450-980℃, more preferably 500-950℃, and even more preferably 550-940℃; And / or, the conditions for the reforming reaction further include: a pressure of 0.5-2.5 MPa, preferably 0.8-2 MPa, more preferably 1-1.5 MPa; And / or, the conditions for the reforming reaction further include: the volume hourly space velocity (VHSV) of the preheated feedstock, calculated as CH4, is 500-2000 h⁻¹. -1 Preferably 800-1500h -1 More preferably 1000-1300h -1 ; And / or, the temperature of the second heat-exchanged reformed gas is 900-980℃, preferably 900-950℃, and more preferably 920-940℃; And / or, the temperature of the synthesis gas is 300-400°C, preferably 320-350°C; And / or, in the synthesis gas, the CH4 content is ≤3.5 mol%, preferably ≤2.5 mol%, more preferably ≤1 mol%, and even more preferably ≤0.7 mol%.

11. The method according to any one of claims 7-10, wherein, In step (3), The reforming catalyst includes a first active component and a first auxiliary agent, wherein the first active component is selected from nickel, and the first auxiliary agent is selected from at least one of lithium, sodium, potassium, magnesium, calcium, copper, cerium and zinc; Preferably, based on the total weight of the reforming catalyst, the content of the first active component is 10-20 wt%, and the content of the first auxiliary agent is 1-5 wt%.

12. The method according to any one of claims 7-10, wherein, The method further includes: under external heating conditions, subjecting the vaporized raw material to the first preheating, and after contacting with the first preconversion catalyst and undergoing the first preconversion, subjecting it to the second preheating, and after contacting with the second preconversion catalyst and undergoing the second preconversion, to obtain the preheated raw material; Preferably, the first preconversion catalyst and the second preconversion catalyst each independently comprise: a second active component and a second auxiliary agent, wherein the second active component is selected from nickel, and the second auxiliary agent is selected from at least one of lithium, sodium, potassium, magnesium, calcium, copper, cerium and zinc; Preferably, based independently on the total weight of the first preconversion catalyst and the second preconversion catalyst, the content of the second active component is 25-40 wt%, and the content of the second auxiliary agent is 1-5 wt%. And / or, the method is carried out in the system of any one of claims 1-5, wherein the raw material undergoes the first heat exchange in the heat recovery zone (I) via the feed pipe (1), and the vaporized raw material undergoes the first preheating and the second preheating in the heat exchange reaction zone (II) and the preheating zone (III) respectively, which are heated by external heating, and the preheated raw material passes through the reaction section from bottom to top, contacts the reforming catalyst packed in the catalyst bed (8) and undergoes the reforming reaction, and the reformed gas undergoes the second heat exchange with the vaporized raw material, and then undergoes the first heat exchange, and the product gas is discharged through the discharge pipe (2).

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