A skid-mounted biogas-to-syngas system

Abstract

The utility model discloses a pry mounted type marsh gas system for synthetic gas relates to marsh gas system for synthetic gas technical field mainly is used for solving the problem of the existing marsh gas system for synthetic gas large floor space, conversion catalyst life low. Its main gas path is equipped with marsh gas preheater, desulfurization jar, marsh gas / conversion gas heat exchanger, preconversion reactor, conversion furnace, water cooler and gas -liquid separator in proper order installed on the warp block, still include the desalted water jar installed on the warp block, and the bottom water outlet of desalted water jar is connected with desalted water pump, desalted water preheater, steam generator and steam superheater installed on the warp block in proper order through the pipeline. The utility model provides a pry mounted type marsh gas system for synthetic gas, and its can prolong the life of conversion catalyst while reducing the floor space of system.

Description

Technical Field

[0001] This utility model relates to the field of biogas to syngas technology, and in particular to a skid-mounted biogas to syngas system. Background Technology

[0002] Biogas is a mixed gas produced by the fermentation of organic matter under anaerobic conditions by microorganisms. Its main component is methane (CH4), typically accounting for 50%-80%, and it also contains gases such as carbon dioxide (CO2) and hydrogen sulfide (H2S). With increasing global emphasis on renewable energy and environmental protection, biogas, as a clean and renewable energy source, has enormous potential for development and utilization.

[0003] Syngas (mainly composed of CO and H2) is an important chemical raw material that can be used to produce various products such as methanol, dimethyl ether, and synthetic oils. It can also be used as fuel for power generation and other applications. Converting biogas into syngas enables the efficient utilization of biogas, meeting the requirements of sustainable development and green energy.

[0004] Currently, the main processes for producing syngas from biogas include steam reforming, carbon dioxide reforming, and partial oxidation. Among these, steam reforming is the most widely used method. A biogas-to-syngas system using this method typically consists of multiple units, such as a pretreatment unit, a conversion reaction unit, and an energy recovery unit.

[0005] However, existing biogas-to-syngas systems have relatively independent units and dispersed equipment layouts, resulting in a large footprint for the entire system. Furthermore, the C2 and higher carbon components in biogas are easily cracked in the converter to form coke, leading to a decrease in catalyst activity and a reduced lifespan. Additionally, existing biogas-to-syngas systems generate a large amount of process condensate during operation. Because the condensate contains dissolved carbon dioxide and is acidic, it cannot be directly reused. To achieve condensate reuse, current technologies often use steam stripping to remove carbon dioxide, which consumes a large amount of steam, further increasing the overall system energy consumption. Utility Model Content

[0006] The purpose of this invention is to provide a skid-mounted biogas to syngas system that reduces the system's footprint while extending the lifespan of the conversion catalyst.

[0007] The technical solution of this utility model to solve the above-mentioned technical problems is: a skid-mounted biogas to syngas system, including a main gas path, wherein a biogas preheater, a desulfurization tank, a biogas / converted gas heat exchanger, a pre-conversion reactor, a conversion furnace, a water cooler and a gas-liquid separator are sequentially installed on the skid along the gas conveying direction, and the top of the gas-liquid separator is connected to a syngas output gas path. It also includes a demineralized water tank installed on the rocker block. The bottom outlet of the demineralized water tank is connected in sequence to a demineralized water pump, a demineralized water preheater, a steam generator, and a steam superheater installed on the rocker block via a pipeline. The steam outlet of the steam superheater is connected to the main gas path between the biogas / converted gas heat exchanger and the pre-conversion reactor via a steam delivery pipe. The main gas path between the converter and the water cooler is arranged along the gas delivery direction, passing through the heat exchange tubes of the biogas / converted gas heat exchanger, the steam generator, and the demineralized water preheater in sequence.

[0008] As a further improvement of this utility model, the bottom of the gas-liquid separator is connected to the side wall of the demineralized water tank through a process condensate output pipeline. The main gas path between the desulfurization tank and the biogas / conversion gas heat exchanger is connected to the side wall of the demineralized water tank below the output end of the process condensate output pipeline through a desulfurized biogas branch pipe. The top of the demineralized water tank is also connected to the main gas path between the output end of the biogas / conversion gas heat exchanger and the steam transmission pipe through a stripping gas output pipe.

[0009] As a further improvement of this utility model, the demineralized water tank is connected to a demineralized water input pipe.

[0010] As a further improvement of this utility model, both the biogas preheater and the steam superheater are electric heaters, and the converter is an electric heating furnace.

[0011] As a further improvement of this utility model, the inner wall of the conversion furnace is provided with a resistance wire wound into a spiral shape, the outer wall of the conversion furnace is provided with a heat insulation layer, and the conversion furnace is also provided with multiple reaction furnace tubes, and the reaction furnace tubes are filled with a conversion catalyst with a porous columnar structure.

[0012] As a further improvement of this invention, the conversion catalyst is a nickel-based catalyst.

[0013] As a further improvement of this utility model, the desulfurization tank is filled with zinc oxide desulfurizing agent.

[0014] As a further improvement of this utility model, the pre-conversion reactor is filled with a nickel-based pre-conversion catalyst.

[0015] As a further improvement of this utility model, the biogas / converted gas heat exchanger, the demineralized water preheater and the water cooler are all shell and tube heat exchangers, and the steam generator is a kettle heat exchanger.

[0016] As a further improvement of this utility model, the gas-liquid separator is a vertical container, and the ratio of the tangential height of the vertical container to the container diameter is 3:1-5:1.

[0017] Beneficial effects

[0018] Compared with existing technologies, the advantages of this skid-mounted biogas to syngas system are as follows: This system integrates all the devices onto a single skid, which effectively utilizes space and saves floor space. At the same time, the integrated installation on a single skid also facilitates transportation, thereby reducing the transportation cost of the devices. Furthermore, in this system, a pre-conversion reactor is set up before the converter to convert the C2 and above heavy hydrocarbons in the feed gas into a mixture of hydrogen, carbon monoxide, and methane, thereby preventing the heavy hydrocarbons from cracking and carbonizing in the converter and thus extending the life of the conversion catalyst. In this system, a stream of desulfurized biogas is introduced into the demineralized water tank from below the output end of the process condensate output pipeline via a desulfurized biogas branch pipe. This allows for the removal of dissolved carbon dioxide from the process condensate through stripping, enabling the process condensate to be recycled and reused. Furthermore, compared to traditional steam stripping methods, this system does not consume a large amount of steam, thus reducing energy consumption. In this system, the conversion catalyst adopts a porous columnar structure. This structure has a large surface area, providing more active sites and facilitating the diffusion of reactant and product molecules, thus promoting efficient conversion reactions. Simultaneously, the columnar structure gives the catalyst good mechanical strength, allowing for tight and uniform packing within the reactor tubes, improving space utilization. Furthermore, the pores within the column serve as heat transfer channels, preventing localized overheating of the catalyst and maintaining its thermal stability at high temperatures, thereby extending catalyst lifespan. All heat sources in this system are electric heating methods. Compared with traditional gas combustion heating methods, electric heating does not produce exhaust gas, which reduces air pollution and is cleaner and more environmentally friendly. At the same time, electric heating can achieve precise control of the heating temperature through a precise temperature control system. In addition, the electric heating element can quickly respond to temperature control commands and accurately adjust the heating power according to the set temperature value, so that the temperature of the heated stream is kept within the set range.

[0019] The present invention will become clearer from the following description and in conjunction with the accompanying drawings, which are used to explain the embodiments of the present invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a top-down structural diagram of the system when it is mounted on a skid.

[0022] The components are as follows: 1-Biogas preheater; 2-Desulfurization tank; 3-Biogas / conversion gas heat exchanger; 4-Pre-conversion reactor; 5-Conversion furnace; 6-Steam generator; 7-Demineralized water preheater; 8-Water cooler; 9-Gas-liquid separator; 10-Steam superheater; 11-Demineralized water tank; 12-Demineralized water pump; 13-Skirt; 14-Main gas path; 15-Synthetic gas output path; 16-Process condensate output pipeline; 17-Demineralized water input pipe; 18-Gas stripping gas output pipe; 19-Steam delivery pipe; 20-Desulfurized biogas branch pipe. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0024] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; of course, they can also refer to a mechanical connection or an electrical connection; furthermore, they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0025] Embodiments of the present invention will now be described with reference to the accompanying drawings.

[0026] Example

[0027] The specific embodiments of this utility model are as follows: Figure 1 As shown, a skid-mounted biogas-to-syngas system includes a main gas path 14. Along the gas transport direction, the main gas path 14 is sequentially equipped with a biogas preheater 1, a desulfurization tank 2, a biogas / syngas heat exchanger 3, a pre-conversion reactor 4, a converter 5, a water cooler 8, and a gas-liquid separator 9. The top of the gas-liquid separator 9 is connected to a syngas output gas path 15. The desulfurization tank 2 is filled with zinc oxide desulfurizing agent, which can reduce the hydrogen sulfide content in the biogas to below 0.1 ppm. Simultaneously, the pre-conversion reactor 4 is filled with a nickel-based pre-conversion catalyst, and the nickel oxide mass fraction of the nickel-based pre-conversion catalyst is 50%.

[0028] In operation, biogas is input into the system from the main gas path 14. After passing through the biogas preheater 1, desulfurization tank 2, biogas / converter heat exchanger 3, pre-conversion reactor 4, converter 5, and water cooler 8 in sequence, it enters the gas-liquid separator 9 for solid-liquid separation, and finally obtains syngas output from the syngas output path 15. In this system, the pre-conversion reactor 4 is set before the converter 5 to convert the C2 and above heavy hydrocarbons in the feed gas into a mixture of hydrogen, carbon monoxide, and methane, thereby avoiding the cracking and carbon deposition of heavy hydrocarbons in the converter 5 and extending the life of the conversion catalyst.

[0029] The system also includes a demineralized water tank 11. The bottom outlet of the demineralized water tank 11 is connected in sequence to a demineralized water pump 12, a demineralized water preheater 7, a steam generator 6, and a steam superheater 10 via pipelines. The steam outlet of the steam superheater 10 is connected to the main gas path 14 between the biogas / converted gas heat exchanger 3 and the pre-conversion reactor 4 via a steam delivery pipe 19. Furthermore, to make efficient use of the high temperature of the gas output from the converter 5, the main gas path 14 between the converter 5 and the water cooler 8 is arranged along the gas delivery direction, passing sequentially through the heat exchange tubes of the biogas / converted gas heat exchanger 3, the steam generator 6, and the demineralized water preheater 7. Therefore, the system does not require external steam supply; the steam required for the conversion reaction is obtained by vaporizing the demineralized water using the waste heat of the converted gas output from the converter 5, thereby reducing energy consumption.

[0030] In this embodiment, as Figure 2 As shown, the biogas preheater 1, desulfurization tank 2, biogas / converted gas heat exchanger 3, pre-conversion reactor 4, converter 5, steam generator 6, demineralized water preheater 7, water cooler 8, gas-liquid separator 9, steam superheater 10, demineralized water tank 11, and demineralized water pump 12 are all mounted on skid 13. This system integrates all the devices onto a single skid 13, effectively utilizing space and saving floor space. Furthermore, the integrated installation on a single skid 13 facilitates transportation, thereby reducing the equipment's transportation costs.

[0031] In this system, the bottom of the gas-liquid separator 9 is connected to the side wall of the demineralized water tank 11 via the process condensate output pipeline 16. The main gas passage 14 between the desulfurization tank 2 and the biogas / converter heat exchanger 3 is connected to the side wall of the demineralized water tank 11 below the output end of the process condensate output pipeline 16 via the desulfurized biogas branch pipe 20. The top of the demineralized water tank 11 is also connected to the main gas passage 14 between the output end of the biogas / converter heat exchanger 3 and the steam transmission pipe 19 via the stripping gas output pipe 18. In this embodiment, a demineralized water input pipe 17 is connected to the demineralized water tank 11. Through the desulfurized biogas branch pipe 20, a stream of desulfurized biogas is introduced into the demineralized water tank 11 from below the output end of the process condensate output pipeline 16, which can remove dissolved carbon dioxide from the process condensate by stripping, thereby enabling the process condensate to be recycled and reused. At the same time, compared with the traditional steam stripping method, the process condensate treatment of this system does not require the consumption of a large amount of steam, thus further reducing energy consumption.

[0032] Furthermore, both the biogas preheater 1 and the steam superheater 10 in this system are electric heaters, thus allowing for control of the outlet gas temperature by adjusting the electric power. The converter 5 is an electric heating furnace; specifically, the inner wall of the converter 5 is equipped with spirally wound resistance wires with a diameter of 5mm-10mm. By adjusting the electric heating power, the furnace temperature can be precisely controlled. The outer wall of the converter 5 is also equipped with a heat insulation layer; the insulation material can be ceramic fiber, rock wool, etc., to reduce heat loss. All heat sources in this system are electrically heated. Compared to traditional gas combustion heating, electric heating does not produce exhaust gases, reducing air pollution and making it cleaner and more environmentally friendly. Simultaneously, electric heating can achieve precise temperature control through a precise temperature control system. In addition, the electric heating elements can quickly respond to temperature control commands and accurately adjust the heating power according to the set temperature value, keeping the temperature of the heated stream within the set range.

[0033] Meanwhile, the conversion furnace 5 is also equipped with multiple reactor tubes made of HP-Nb material, with an outer diameter of 100mm-150mm and an effective length of 3m-12m. The reactor tubes are filled with a porous columnar conversion catalyst. Specifically, the conversion catalyst is cylindrical in shape, with a diameter of approximately 10mm-20mm and a length of 5mm-20mm, and four evenly distributed circular holes with a diameter of 2mm-8mm at the center of the cylinder. In this embodiment, the conversion catalyst is a nickel-based catalyst, and the nickel oxide mass fraction in the nickel-based catalyst is 10%-20%. The porous columnar structure of the conversion catalyst has a large surface area, providing more active sites and facilitating the diffusion of reactant and product molecules, thus promoting efficient conversion reactions. Simultaneously, the columnar structure gives the conversion catalyst good mechanical strength, allowing for tight and uniform packing in the reactor tubes, which improves the space utilization of the reactor tubes. Furthermore, the pores in the column can also serve as heat transfer channels, preventing localized overheating of the catalyst and maintaining its thermal stability at high temperatures, thereby improving catalyst lifespan.

[0034] In addition, the biogas / converted gas heat exchanger 3, the demineralized water preheater 7, and the water cooler 8 in this system are all shell-and-tube heat exchangers. The steam generator 6 is a vessel-type heat exchanger with a vessel diameter to tube bundle diameter ratio of 1.5:1 to 3:1. When the steam generator 6 is in use, the converted gas flows through the tubes, and the demineralized water enters the vessel, is heated by the converted gas, vaporizes, and generates saturated steam, which exits from the top of the vessel.

[0035] In this embodiment, the gas-liquid separator 9 is a vertical container, and the ratio of the tangential height to the container diameter is 3:1 to 5:1. A wire mesh demister is installed on the upper part of the gas-liquid separator 9. The wire mesh demister can be 100mm or 150mm thick, and the wire mesh porosity is 0.975-0.985.

[0036] The specific usage process of this system is as follows: First, biogas, used as feedstock, is input into the system through the main pipeline 14. After being heated to 320℃-400℃ by the biogas preheater 1, it is sent to the desulfurization tank 2. The desulfurization tank 2 is filled with zinc oxide desulfurizing agent, which has a zinc oxide mass fraction ≥95%, and is cylindrical in shape with a diameter of approximately 4mm-8mm, a length of 4mm-15mm, and a bulk density of 0.95g / mL-1.1g / mL. The hydrogen sulfide content in the biogas at the outlet of the desulfurization tank 2 is <0.1ppm(mol), thus preventing the conversion catalyst in the converter 5 from being deactivated due to sulfur poisoning.

[0037] Then, the desulfurized biogas output from desulfurization tank 2 is divided into two streams. One stream of desulfurized biogas is heated to 560°C by exchanging heat with converted gas in biogas / converter gas heat exchanger 3. It then mixes with stripped gas from demineralized water tank 11 and superheated steam from steam superheater 10 to obtain mixed feed gas. The temperature of the superheated steam is approximately 560°C, and its molar ratio with methane in the biogas is 2.8-4.0. The other stream of desulfurized biogas is introduced from the bottom of demineralized water tank 11, forming bubbles that rise upwards. Due to the low carbon dioxide concentration in the bubbles, dissolved carbon dioxide in the water is transferred from the aqueous phase to the gas phase, i.e., the stripping effect. As the desulfurized biogas bubbles rise, they continuously carry carbon dioxide released from the process condensate, forming stripped gas, which is eventually discharged from the stripped gas output pipe 18 at the top of demineralized water tank 11. The process condensate, after being decarbonized, is neutral and can be reused.

[0038] Next, the mixed feed gas enters the pre-conversion reactor 4. In the pre-conversion reactor 4, the C2 and heavier alkane components in the mixed feed gas undergo a pre-conversion reaction with water vapor on the pre-conversion catalyst to produce hydrogen, carbon monoxide, and methane, with a conversion rate of more than 98%. This avoids excessive C2 and heavier alkane components from cracking into carbon in the conversion furnace 5, which would cause deactivation of the conversion catalyst.

[0039] Subsequently, the pre-converted gas output from the pre-conversion reactor 4 enters the converter 5 for conversion reaction. Specifically, biogas and water vapor undergo a conversion reaction in converter 5 to obtain converted gas. The converted gas temperature is 750℃-850℃, the pressure is 0.1MPa-3.5MPa, and the space velocity is 500h⁻¹. -1- 1500h -1 The methane conversion rate in biogas can reach over 95%.

[0040] Finally, the converted gas output from converter 5 passes sequentially through biogas / converted gas heat exchanger 3, steam generator 6, demineralized water preheater 7, and water cooler 8. After being cooled to 40℃-45℃, it enters gas-liquid separator 9 to remove moisture from the converted gas, yielding process condensate and syngas. The process condensate is discharged to demineralized water tank 11 for reuse, while the syngas is delivered to users as product gas.

[0041] Meanwhile, the system also recovers waste heat: the demineralized water output from the demineralized water tank 11 is pressurized by the demineralized water pump 12 to obtain pressurized demineralized water. After heat exchange in the demineralized water preheater 7 and the steam generator 5, the pressurized demineralized water becomes saturated steam, which is then heated to approximately 560°C by the steam superheater 10 to obtain superheated steam. The superheated steam is mixed with the heated biogas to obtain mixed feed gas. Thus, the system can fully recover waste heat from the converted gas and simultaneously convert demineralized water into steam, eliminating the need to introduce additional steam from outside the unit and reducing energy consumption.

[0042] The present invention has been described above in conjunction with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations made in accordance with the essence of the present invention.

Claims

1. A skid-mounted biogas to syngas system, comprising a main gas path (14), characterized in that, The main gas path (14) is provided with a biogas preheater (1), a desulfurization tank (2), a biogas / converted gas heat exchanger (3), a pre-conversion reactor (4), a converter (5), a water cooler (8), and a gas-liquid separator (9) installed on the rocker block (13) in sequence along the gas conveying direction. The top of the gas-liquid separator (9) is connected to a syngas output gas path (15). It also includes a demineralized water tank (11) installed on the rocker block (13). The bottom outlet of the demineralized water tank (11) is connected in sequence to a demineralized water pump (12), a demineralized water preheater (7), a steam generator (6), and a steam superheater (10) installed on the rocker block (13). The steam outlet of the steam superheater (10) is connected to the main gas path (14) between the biogas / converted gas heat exchanger (3) and the pre-conversion reactor (4) through a steam delivery pipe (19). The main gas path (14) between the converter (5) and the water cooler (8) is set along the gas delivery direction through the heat exchange tubes of the biogas / converted gas heat exchanger (3), the steam generator (6), and the demineralized water preheater (7).

2. The skid-mounted biogas to syngas system according to claim 1, characterized in that, The bottom of the gas-liquid separator (9) is connected to the side wall of the demineralized water tank (11) through the process condensate output pipeline (16). The main gas path (14) between the desulfurization tank (2) and the biogas / converted gas heat exchanger (3) is connected to the side wall of the demineralized water tank (11) below the output end of the process condensate output pipeline (16) through the desulfurized biogas branch pipe (20). The top of the demineralized water tank (11) is also connected to the main gas path (14) between the output end of the biogas / converted gas heat exchanger (3) and the steam conveying pipe (19) through the stripping gas output pipe (18).

3. The skid-mounted biogas to syngas system according to claim 1 or 2, characterized in that, The demineralized water tank (11) is connected to a demineralized water inlet pipe (17).

4. The skid-mounted biogas to syngas production system according to claim 1, characterized in that, The biogas preheater (1) and the steam superheater (10) are both electric heaters, and the converter (5) is an electric heating furnace.

5. The skid-mounted biogas to syngas production system according to claim 4, characterized in that, The inner wall of the converter (5) is provided with a resistance wire wound into a spiral shape, and the outer wall of the converter (5) is provided with a heat insulation layer. The converter (5) is also provided with multiple reaction furnace tubes, and the reaction furnace tubes are filled with a conversion catalyst with a porous columnar structure.

6. The skid-mounted biogas to syngas system according to claim 5, characterized in that, The conversion catalyst is a nickel-based catalyst.

7. The skid-mounted biogas to syngas production system according to claim 1, characterized in that, The desulfurization tank (2) is filled with zinc oxide desulfurizing agent.

8. The skid-mounted biogas to syngas system according to claim 1, characterized in that, The preconversion reactor (4) is filled with a nickel-based preconversion catalyst.

9. The skid-mounted biogas to syngas production system according to claim 1, characterized in that, The biogas / converted gas heat exchanger (3), the demineralized water preheater (7) and the water cooler (8) are all shell-and-tube heat exchangers, and the steam generator (6) is a kettle heat exchanger.

10. The skid-mounted biogas to syngas production system according to claim 1, characterized in that, The gas-liquid separator (9) is a vertical container, and the ratio of the tangential height of the vertical container to the container diameter is 3:1-5:1.

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