System for preparing methanol from biogas

Abstract

The utility model provides a system for preparing methanol from biogas and relates to the field of biogas treatment. The system comprises a raw material treatment assembly and a methanol synthesis assembly communicated with the raw material treatment assembly, the raw material treatment assembly comprises a biogas buffer tank, a biogas compressor, a biogas desulfurization and decarbonization device, a biogas reforming device, a steam generator and a water cooler which are communicated in sequence, the biogas buffer tank is connected with an external biogas source, the water cooler is communicated with the methanol synthesis assembly, and a purge gas outlet of the methanol synthesis assembly is communicated with the biogas reforming device; the steam generator is connected with a desalted water booster pump; the desalted water booster pump is communicated with the steam generator and the methanol synthesis assembly, and steam generated by the steam generator and the methanol synthesis assembly enters the biogas reforming device to serve as raw material water for reforming. According to the utility model, sulfur and excessive carbon dioxide in the methane can be removed, the requirement of methanol synthesis can be met in the subsequent treatment process, the process flow is simplified, and the equipment investment is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of biogas treatment, in particular to a system for preparing methanol from biogas. Background Art

[0002] The carbon dioxide and methane contained in biogas provide the source of the basic elements C, H, and O required for the preparation of methanol. For the preparation of methanol, the carbon dioxide content in biogas is generally excessive. Therefore, it is necessary to separate the excess CO2 in the biogas, and then carry out high-temperature reforming reaction to obtain synthesis gas. After the high-temperature synthesis gas is cooled, it is sent to the methanol synthesis tower for synthesis reaction to produce methanol.

[0003] The existing devices for treating biogas have complicated equipment, which makes the biogas treatment process complicated. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a system for preparing methanol from biogas. In the system for preparing methanol from biogas, a biogas desulfurization and decarbonization device is used to not only remove sulfur in the biogas, but also partially remove excess carbon dioxide therein. The synthesis gas prepared in the biogas reforming device can meet the demand for methanol synthesis, and there is no need to supplement hydrogen; the process is simplified and the equipment investment is reduced.

[0005] The technical solution adopted by the utility model is:

[0006] A system for preparing methanol from biogas, comprising:

[0007] A feedstock processing component and a methanol synthesis component connected to the feedstock processing component;

[0008] Wherein, the raw material processing component comprises:

[0009] A biogas buffer tank, a biogas compressor, a biogas desulfurization and decarbonization device, a biogas reforming device, a steam generator and a water cooler are connected in sequence, wherein the biogas buffer tank is connected to an external biogas source, the water cooler is connected to the methanol synthesis component, the purge gas outlet of the methanol synthesis component is connected to the biogas reforming device, and the steam generator is connected to a desalted water booster pump;

[0010] The desalted water booster pump is in communication with the steam generator and the methanol synthesis component, and the desalted water processed by the steam generator and the methanol synthesis component is circulated into the biogas reforming device.

[0011] Optionally, the biogas compressor compresses the biogas to 10-30 bar and then sends it to the biogas desulfurization and decarbonization device.

[0012] Optionally, the methanol synthesis component comprises:

[0013] a synthesis gas compressor, connected to the water cooler;

[0014] a heat exchanger, wherein the synthesis gas compressor is in communication with a cold process passage of the heat exchanger;

[0015] A methanol synthesis tower, the inlet of which is in communication with the cold process channel of the heat exchanger, and the outlet of which is in communication with the hot process channel of the heat exchanger;

[0016] a circulating gas cooler in communication with a hot process channel of the heat exchanger;

[0017] A methanol separator, the inlet of which is in communication with the circulating gas cooler, and the purge gas in the methanol separator is transported to the biogas reforming device;

[0018] A circulating gas compressor is connected to the methanol separator, and an outlet of the circulating gas compressor is connected to the cold process channel of the heat exchanger.

[0019] Optionally, the synthesis gas compressor compresses the gas to 40-60 bar and then transports it to the heat exchanger.

[0020] Optionally, the heat exchanger is disposed in the methanol synthesis tower.

[0021] Compared with the prior art, the beneficial effects of the utility model are:

[0022] 1. When preparing methanol, the only raw materials required are biogas and water. There is no carbon emission in the production process, which reduces environmental pollution.

[0023] 2. The biogas desulfurization and decarbonization device not only removes sulfur from the biogas, but also partially removes excess carbon dioxide. The synthesis gas produced in the biogas reforming device can meet the needs of methanol synthesis, and there is no need to supplement hydrogen; it simplifies the process and reduces equipment investment.

[0024] 3. The heat exchanger is arranged inside the methanol synthesis tower, so that the pressure inside and outside the heat exchanger is basically the same, the pressure is small, and the manufacturing cost of the heat exchanger can be reduced.

[0025] 4. Due to the presence of inert components such as CH4 and N2 in methanol synthesis, in order to avoid excessive inert component content in the synthesis system, resulting in low system efficiency, a portion of the gas phase separated in the methanol separator must be released out of the system, and this portion of gas returns to the fuel system of the biogas reforming device for combustion to provide heat for the reforming reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the system for producing methanol from biogas.

[0028] Reference numerals:

[0029] 1. Raw material processing components; 11. Biogas buffer tank; 12. Biogas compressor; 13. Biogas desulfurization and decarbonization device; 14. Biogas reforming device; 15. Steam generator; 16. Water cooler; 17. Desalted water booster pump;

[0030] 2. Methanol synthesis component; 21. Synthesis gas compressor; 22. Heat exchanger; 23. Methanol synthesis tower; 24. Circulating gas cooler; 25. Methanol separator; 26. Circulating gas compressor. DETAILED DESCRIPTION

[0031] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0032] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0034] The embodiments of the present utility model are described in detail below with reference to the accompanying drawings.

[0035] The embodiment of the utility model provides a system for preparing methanol from biogas, comprising: a raw material processing component 1 and a methanol synthesis component 2 connected to the raw material processing component 1.

[0036] Among them, the raw material processing component 1 includes: a biogas buffer tank 11, a biogas compressor 12, a biogas desulfurization and decarbonization device 13, a biogas reforming device 14, a steam generator 15 and a water cooler 16 which are connected in sequence, the biogas buffer tank 11 is connected to an external biogas source, the water cooler 16 is connected to the methanol synthesis component 2, the purge gas outlet of the methanol synthesis component 2 is connected to the biogas reforming device 14, and the steam generator 15 is connected to a desalted water booster pump 17.

[0037] The desalted water booster pump 17 is connected to the steam generator 15 and the methanol synthesis component 2, and the water vapor generated after being processed by the steam generator 15 and the methanol synthesis component 2 is sent to the biogas reforming device 14 as raw water for reforming.

[0038] In one embodiment, the biogas compressor 12 compresses the biogas to 10-30 bar and then sends it to the biogas desulfurization and decarbonization device 13.

[0039] In one embodiment, the methanol synthesis component 2 includes: a synthesis gas compressor 21, a heat exchanger 22, a methanol synthesis tower 23, a circulating gas cooler 24, a methanol separator 25 and a circulating gas compressor 26. The synthesis gas compressor 21 is in communication with the water cooler 16. The synthesis gas compressor 21 is in communication with the cold process channel of the heat exchanger 22. The inlet of the methanol synthesis tower 23 is in communication with the cold process channel of the heat exchanger 22, and the outlet of the methanol synthesis tower 23 is in communication with the hot process channel of the heat exchanger 22. The circulating gas cooler 24 is in communication with the hot process channel of the heat exchanger 22. The inlet of the methanol separator 25 is in communication with the circulating gas cooler 24, and the purge gas in the methanol separator 25 is transported to the biogas reforming device 14. The circulating gas compressor 26 is in communication with the methanol separator 25, and the outlet of the circulating gas compressor 26 is in communication with the cold process channel of the heat exchanger 22.

[0040] Due to the presence of inert components such as CH4 and N2 in methanol synthesis, in order to avoid excessive inert component content in the synthesis system, resulting in low system efficiency, the gas phase separated in the methanol separator 25 must be released to flow out of the system, and this part of the gas returns to the fuel system of the biogas reforming device 14 to be burned to provide heat for the reforming reaction.

[0041] In one embodiment, the synthesis gas compressor 21 compresses the gas to 40-60 bar and then transmits it to the heat exchanger 22.

[0042] In one of the embodiments, the heat exchanger is disposed inside the methanol synthesis tower 23, so that the pressure inside and outside the heat exchanger is substantially the same, the pressure it bears is small, and the manufacturing cost of the heat exchanger can be reduced.

[0043] It should be noted that the biogas buffer tank 11, biogas compressor 12, biogas desulfurization and decarbonization device 13, biogas reforming device 14, steam generator 15, water cooler 16, desalted water booster pump 17, synthesis gas compressor 21, heat exchanger 22, methanol synthesis tower 23, circulating gas cooler 24, methanol separator 25 and circulating gas compressor 26 are all existing technologies and can be purchased and used in actual use.

[0044] Specific process of preparing methanol from biogas:

[0045] The low-pressure biogas enters the biogas buffer tank 11, where the liquid water that may be carried is separated and serves as a buffer for the biogas compressor 12. The biogas is compressed to 10-30 bar and enters the biogas desulfurization and decarbonization device 13. The sulfur in the biogas and the excess carbon dioxide for the back-end methanol synthesis are removed under pressure, and the biogas enters the biogas reforming device 14. The CH4 in the biogas is mixed with water vapor and undergoes a water vapor reforming reaction at high temperature to produce the raw material synthesis gas required for methanol synthesis. The high-temperature synthesis gas is cooled to room temperature through the steam generator 15 and the water cooler 16 in turn, enters the synthesis gas compressor 21 to be pressurized to 40-60 bar, and is mixed with the circulating gas as a fresh gas supplement for methanol synthesis and enters the heat exchanger 22 to be preheated to a certain temperature before entering the methanol synthesis tower 23. The methanol synthesis reaction occurring in the methanol synthesis tower 23 is an exothermic reaction. The temperature in the tower is maintained by water heat transfer. The gas leaving the tower passes through the heat exchanger 22 and the circulating gas cooler 24 in sequence and is cooled to room temperature and condensed into liquid methanol. The liquid methanol is separated in the methanol separator 25 and sent out as a product. Part of the separated gas phase enters the circulating gas compressor 26 for pressurization and circulation, and the remaining part is returned to the biogas reforming device 14 as the purge gas for combustion and heat supply.

[0046] The desalted water booster pump 17 is used to increase the pressure of the desalted water and generate steam in the steam generator 15 and the methanol synthesis tower 23 . The generated steam is used as raw water vapor for the biogas reforming device 14 .

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A system for preparing methanol from biogas, characterized in that: include: A feedstock processing component and a methanol synthesis component connected to the feedstock processing component; Wherein, the raw material processing component comprises: A biogas buffer tank, a biogas compressor, a biogas desulfurization and decarbonization device, a biogas reforming device, a steam generator and a water cooler are connected in sequence, wherein the biogas buffer tank is connected to an external biogas source, the water cooler is connected to the methanol synthesis component, the purge gas outlet of the methanol synthesis component is connected to the biogas reforming device, and the steam generator is connected to a desalted water booster pump; The desalted water booster pump is connected to the steam generator and the methanol synthesis component, and the water vapor generated after being processed by the steam generator and the methanol synthesis component is sent to the biogas reforming device as raw water for reforming.

2. The system for preparing methanol from biogas according to claim 1, characterized in that: The biogas compressor compresses the biogas to 10-30 bar and then sends it to the biogas desulfurization and decarbonization device.

3. The system for preparing methanol from biogas according to claim 1, characterized in that: The methanol synthesis component comprises: a synthesis gas compressor, connected to the water cooler; a heat exchanger, wherein the synthesis gas compressor is in communication with a cold process passage of the heat exchanger; A methanol synthesis tower, the inlet of which is in communication with the cold process channel of the heat exchanger, and the outlet of which is in communication with the hot process channel of the heat exchanger; a circulating gas cooler in communication with a hot process channel of the heat exchanger; A methanol separator, the inlet of which is in communication with the circulating gas cooler, and the purge gas in the methanol separator is transported to the biogas reforming device; A circulating gas compressor is connected to the methanol separator, and an outlet of the circulating gas compressor is connected to the cold process channel of the heat exchanger.

4. The system for preparing methanol from biogas according to claim 3, characterized in that: The synthesis gas compressor compresses the gas to 40-60 bar and then transports it to the heat exchanger.

5. The system for preparing methanol from biogas according to claim 3, characterized in that: The heat exchanger is arranged in the methanol synthesis tower.

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