System for preparing methanol and co-producing formic acid through biomass gasification

Abstract

The invention discloses a system for preparing methanol and co-producing formic acid by biomass gasification, which belongs to the technical field of formic acid production and comprises a methanol production line and a formic acid production line. The methanol production line comprises a synthesis gas preparation unit, a methanol preparation unit and a methanol purification and storage unit, wherein the synthesis gas preparation unit comprises a biomass gasification device, a dust removal device, a water gas shift reaction device and an acid gas removal device; the formic acid production line comprises a formic acid preparation unit and a formic acid purification and storage unit, the formic acid preparation unit comprises a carbon dioxide electroreduction pool, and the carbon dioxide electroreduction pool is connected with the acid gas removal device and the formic acid purification and storage unit. According to the method, methanol can be produced by utilizing biomass gasification treatment, carbon dioxide produced in the methanol production process is captured, and the carbon dioxide is successfully converted into formic acid through coupling of the carbon dioxide electroreduction pool, so that green co-production of methanol and formic acid with zero carbon emission is realized, and the method conforms to the green and environment-friendly development concept and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of formic acid production, in particular to a biomass gasification methanol co-production system. BACKGROUND

[0002] Formic acid, also known as ant acid, is an important chemical raw material, widely used in pesticide, chemical, leather, medical and rubber fields. Among them, the medical and food chemical field accounts for about 31.2%, the organic raw material field accounts for about 10.0%, and the pesticide field accounts for about 12.8%. With the continuous development of these downstream industries, the demand for formic acid will continue to grow. The traditional industrial synthesis method of formic acid has significant limitations. Among them, the sodium formate method causes serious environmental burden due to the generation of a large amount of high-salt and difficult-to-treat wastewater; the methanol carbonylation synthesis method involves high-purity carbon monoxide raw materials, high-pressure reaction systems and multi-step separation and purification processes, which are harsh and costly. These technical bottlenecks seriously restrict the sustainable development of the formic acid production field.

[0003] Therefore, there is an urgent need for a new formic acid production process. SUMMARY

[0004] The purpose of the present application is to solve the above technical problems, provide a biomass gasification methanol co-production system, which can produce methanol by biomass gasification treatment, capture carbon dioxide produced in the methanol production process, and successfully convert carbon dioxide into formic acid through the coupling of the carbon dioxide electro-reduction pool, realizing the green co-production of zero-carbon emission methanol and formic acid, conforming to the development concept of green environmental protection, and having wide application prospect.

[0005] To achieve the above purpose, the present application provides the following scheme: the present application discloses a biomass gasification methanol co-production system, which comprises a methanol production line and a formic acid production line; The methanol production line comprises a synthesis gas preparation unit, a methanol preparation unit and a methanol purification and storage unit, the synthesis gas preparation unit comprises a biomass gasification device, a dust removal device, a water gas shift reaction device and an acid gas removal device, the biomass gasification device comprises an oxygen inlet, a biomass inlet and a synthesis gas outlet, the synthesis gas outlet is connected with the gas inlet of the dust removal device, the water gas shift reaction device comprises a water vapor inlet, a synthesis gas inlet and a reaction gas outlet, the synthesis gas inlet is connected with the gas outlet of the dust removal device, the reaction gas outlet and the gas outlet of the dust removal device are both connected with the gas inlet of the acid gas removal device, the gas outlet of the acid gas removal device is connected with the methanol preparation unit, and the methanol preparation unit is connected with the methanol purification and storage unit; The formic acid production line comprises a formic acid preparation unit and a formic acid purification and storage unit, the formic acid preparation unit comprises a carbon dioxide electro-reduction tank, the carbon dioxide inlet of the carbon dioxide electro-reduction tank is connected with the carbon dioxide outlet of the acid gas removal device, and the formic acid aqueous solution outlet of the carbon dioxide electro-reduction tank is connected with the formic acid purification and storage unit.

[0006] Preferably, the synthesis gas preparation unit further comprises a water vapor source, the water vapor source comprises a first conveying pump and a first heat exchanger, the inlet of the first conveying pump is connected with a water source, and the first heat exchanger is connected between the outlet of the first conveying pump and the water vapor inlet of the water gas shift reaction device.

[0007] Preferably, the synthesis gas preparation unit further comprises an air separation device, the air inlet of the air separation device is provided for air to enter, and the oxygen outlet of the air separation device is connected with the oxygen inlet of the biomass gasification device.

[0008] Preferably, the synthesis gas preparation unit further comprises a first flow divider, a first mixer, a second heat exchanger and a third heat exchanger, the second heat exchanger is connected between the gas outlet of the dust removal device and the inlet of the first flow divider, the first outlet of the first flow divider is connected with the synthesis gas inlet of the water gas shift reaction device, the second outlet of the first flow divider is connected with the first inlet of the first mixer, the reaction gas outlet of the water gas shift reaction device is connected with the second inlet of the first mixer, and the third heat exchanger is connected between the gas outlet of the first mixer and the gas inlet of the acid gas removal device.

[0009] Preferably, the methanol preparation unit comprises a first flash device, a second mixer, a first compressor, a fourth heat exchanger, a methanol synthesis device, a second flash device and a second conveying pump; the gas inlet of the first flash device is connected with the gas outlet of the acid gas removal device, the water outlet of the first flash device is externally discharged, the gas outlet of the first flash device is connected with the first inlet of the second mixer, the outlet of the second mixer is connected with the gas inlet of the first compressor, the fourth heat exchanger is connected between the gas outlet of the first compressor and the gas inlet of the methanol synthesis device, the methanol outlet of the methanol synthesis device is connected with the liquid inlet of the second flash device, the gas outlet of the second flash device is connected with the second inlet of the second mixer, and the liquid outlet of the second flash device is connected with the methanol purification and storage unit through the second conveying pump.

[0010] Preferably, the methanol purification and storage unit comprises a methanol purification device and a methanol storage tank, the liquid inlet of the methanol purification device is connected with the methanol preparation unit, and the liquid outlet of the methanol purification device is connected with the methanol storage tank.

[0011] Preferably, the formic acid preparation unit further comprises a third flash device, the carbon dioxide electro-reduction cell comprises a cathode chamber, a center chamber and an anode chamber; the cathode chamber is provided with a carbon dioxide inlet and a carbon dioxide outlet, the carbon dioxide inlet of the cathode chamber is connected with the carbon dioxide outlet of the acid gas removal device, and the carbon dioxide outlet of the cathode chamber is connected with the carbon dioxide inlet of the cathode chamber; the center chamber is provided with a first water source inlet and a formic acid aqueous solution outlet, the formic acid aqueous solution outlet is connected with the formic acid purification and storage unit, the anode chamber is provided with a second water source inlet and a water-oxygen mixed outlet, the water-oxygen mixed outlet is connected with the gas inlet of the third flash device, the gas outlet of the third flash device is connected with the oxygen inlet of the biomass gasification device, and the water outlet of the third flash device is externally discharged.

[0012] Preferably, the formic acid purification and storage unit comprises a third mixer, a third delivery pump, a formic acid purification device and a formic acid storage tank, the first inlet of the third mixer is connected with the formic acid aqueous solution outlet, the outlet of the third mixer is connected with the liquid inlet of the formic acid purification device through the third delivery pump, the formic acid outlet of the formic acid purification device is connected with the formic acid storage tank, and the residual liquid outlet of the formic acid purification device is connected with the second inlet of the third mixer.

[0013] Preferably, the formic acid purification and storage unit comprises multiple groups of the formic acid purification device arranged in sequence along a production direction, the liquid inlet of the formic acid purification device of a previous stage is connected with the third delivery pump, the formic acid outlet of the formic acid purification device of the previous stage is connected with the liquid inlet of the formic acid purification device of a next stage, the formic acid outlet of the formic acid purification device of the next stage is connected with the formic acid storage tank, and the residual liquid outlet of the formic acid purification device of a tail stage is connected with the second inlet of the third mixer.

[0014] Preferably, the formic acid production line further comprises a power smoothing unit, the power smoothing unit comprises a second diverter, a second compressor, a fifth heat exchanger, a carbon dioxide storage tank, a sixth heat exchanger and a control valve, the inlet of the second diverter is connected with the carbon dioxide outlet of the acid gas removal device, the first outlet of the second diverter is connected with the carbon dioxide inlet, the second outlet of the second diverter is connected with the gas inlet of the second compressor, the fifth heat exchanger is connected between the gas outlet of the second compressor and the inlet of the carbon dioxide storage tank, the sixth heat exchanger is connected between the outlet of the carbon dioxide storage tank and the control valve, and the control valve is connected with the carbon dioxide inlet of the carbon dioxide electro-reduction cell.

[0015] The present application has the following technical effects relative to the prior art: Compared with the traditional methanol synthesis process, the advanced synthesis process is adopted in the application, the energy utilization rate of biomass is improved from the aspects of biomass gasification treatment, syngas dust removal, hydrogenation, carbon dioxide removal and the like, the captured carbon dioxide is successfully converted into formic acid through coupling a carbon dioxide electro-reduction tank, zero carbon emission is realized, no pollution is generated, green production of methanol and formic acid is realized, the development concept of green environmental protection is met, and the application prospect is wide.

[0016] The other technical solutions of the application also have the following technical effects relative to the prior art: In the application, by connecting the carbon dioxide storage tank, the carbon dioxide entering the carbon dioxide electro-reduction tank can be adjusted in real time according to the fluctuation of electric power, the fluctuation of electric power is suppressed, and zero carbon emission is further realized. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiments will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0018] Fig. 1 It is a structure schematic diagram of the biomass gasification methanol co-production formic acid system in the embodiments of the application. Fig. 2 It is a production flow chart of the biomass gasification methanol co-production formic acid system in the embodiments of the application.

[0019] The reference signs are explained as follows: 1, air separation device; 2, biomass gasification device; 3, dust removal device; 4, water-gas shift reaction device; 5, acid gas removal device; 6, first delivery pump; 7, first heat exchanger; 8, second heat exchanger; 9, first flow divider; 10, first mixer; 11, third heat exchanger; 12, first flash device; 13, second mixer; 14, first compressor; 15, fourth heat exchanger; 16, methanol synthesis device; 17, second flash device; 18, second delivery pump; 19, methanol purification device; 20, methanol storage tank; 21, carbon dioxide electro-reduction tank; 22, third mixer; 23, third delivery pump; 24, formic acid purification device; 25, formic acid storage tank; 26, third flash device; 27, second flow divider; 28, second compressor; 29, fifth heat exchanger; 30, carbon dioxide storage tank; 31, sixth heat exchanger; 32, control valve; 33, cathode chamber; 34, center chamber; 35, anode chamber. DETAILED DESCRIPTION

[0020] With reference to the accompanying drawings: the technical solutions in the embodiments of the present application will be apparently and completely described, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments analyzed and obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present application.

[0021] The purpose of the present application is to provide a biomass gasification methanol co-production system for formic acid, to solve the problems existing in the prior art, compared with the traditional methanol synthesis process, the present application adopts a more advanced synthesis process, from biomass gasification treatment, synthesis gas dust removal, hydrogenation, removal of carbon dioxide and other aspects, improves the energy utilization rate of biomass, through coupling the carbon dioxide electric reduction pool, successfully converts the captured carbon dioxide into formic acid, realizes zero carbon emission, does not produce pollution, realizes the green production of methanol and formic acid, conforms to the development concept of green environmental protection, has a broad application prospect.

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0023] As shown in Figs. 1-2 The present embodiment provides a biomass gasification methanol co-production system for formic acid, which comprises a methanol production line and a formic acid production line.

[0024] The methanol production line comprises a synthesis gas preparation unit, a methanol preparation unit and a methanol purification and storage unit. The synthesis gas preparation unit comprises a biomass gasification device 2, a dust removal device 3, a water gas shift reaction device 4 and an acid gas removal device 5. The biomass gasification device 2 comprises an oxygen inlet, a biomass inlet and a synthesis gas outlet, the oxygen inlet is used for supplying oxygen, the biomass inlet is used for supplying biomass (such as wood chips, etc.), and the synthesis gas outlet is connected with the gas inlet of the dust removal device 3. The water gas shift reaction device 4 comprises a water vapor inlet, a synthesis gas inlet and a reaction gas outlet, the water vapor inlet is used for supplying water vapor, the synthesis gas inlet is connected with the gas outlet of the dust removal device 3, and the reaction gas outlet and the gas outlet of the dust removal device 3 are both connected with the gas inlet of the acid gas removal device 5. The gas outlet of the acid gas removal device 5 is connected with the methanol preparation unit. The methanol preparation unit is connected with the methanol purification and storage unit.

[0025] The formic acid production line comprises a formic acid preparation unit and a formic acid purification and storage unit. The formic acid preparation unit comprises a carbon dioxide electric reduction pool 21, the carbon dioxide inlet of the carbon dioxide electric reduction pool 21 is connected with the carbon dioxide outlet of the acid gas removal device 5, and the formic acid aqueous solution outlet of the carbon dioxide electric reduction pool 21 is connected with the formic acid purification and storage unit.

[0026] Working principle: First, oxygen is introduced into the biomass gasification device 2 through the oxygen inlet, and biomass is introduced into the biomass gasification device 2 through the biomass inlet. The biomass gasification device 2 uses oxygen to oxidize the biomass, and obtains synthesis gas (containing hydrogen, carbon monoxide and carbon dioxide); Then, the synthesis gas generated by the biomass gasification device 2 is transported to the dust removal device 3 through the synthesis gas outlet. After removing the dust in the synthesis gas, part of the synthesis gas enters the water gas shift reaction device 4 to perform a water gas shift reaction (reaction process: ) with the water vapor introduced through the water vapor inlet, so as to increase the content of hydrogen in the synthesis gas; the other part of the synthesis gas is mixed with the synthesis gas after hydrogenation, and is transported to the acid gas removal device 5 to remove excess carbon dioxide in the synthesis gas, so that the proportion of in the synthesis gas is maintained at 2.05~2.15; Then, the synthesis gas after the acid gas removal device 5 is sent to the methanol preparation unit to synthesize crude methanol (reaction process: and ), and then the methanol is introduced into the methanol purification and storage unit to separate and purify pure methanol from the crude methanol containing synthesis gas, and to store the pure methanol. At the same time, the carbon dioxide captured by the acid gas removal device 5 is discharged through the carbon dioxide outlet into the carbon dioxide electric reduction pool 21 of the formic acid preparation unit to produce an aqueous solution containing formic acid, and the formic acid purification and storage unit is used to separate and purify pure formic acid from the aqueous solution containing formic acid, and to store the pure formic acid.

[0027] In an embodiment, the biomass gasification device 2 uses a gas flow bed gasification furnace, and the biomass raw material uses oxygen as an oxidant to obtain synthesis gas, and the slag generated by the gas flow bed gasification furnace is discharged.

[0028] In an embodiment, the dust removal method of the dust removal device 3 at least uses one of the following: inertial dust removal method, cyclone dust removal method, bag dust removal method and electrostatic dust removal method. That is, the dust removal device 3 at least includes one of an inertial dust remover, a cyclone dust remover, a bag dust remover and an electrostatic dust remover.

[0029] In an embodiment, the acid gas removal device 5 is used to remove CO2 in the synthesis gas, and the removal method at least uses one of the following: chemical adsorption method, low-temperature rectification method, membrane separation method and adsorption separation method. That is, the acid gas removal device 5 at least includes one of a chemical adsorption remover, a low-temperature rectification remover, a membrane separation remover and an adsorption separation remover.

[0030] In an embodiment, the syngas preparation unit further comprises a water vapor source, the water vapor source comprising a first delivery pump 6 and a first heat exchanger 7, an inlet of the first delivery pump 6 being connected to a water source, an outlet of the first delivery pump 6 being connected to the first heat exchanger 7, and the first heat exchanger 7 being connected to a water vapor inlet of the water gas shift reaction device 4. Working principle: the first delivery pump 6 can provide water for the first heat exchanger 7, and the water heated by the first heat exchanger 7 forms water vapor to be supplied into the water gas shift reaction device 4.

[0031] In an embodiment, the syngas preparation unit further comprises an air separation device 1, an air inlet of the air separation device 1 being connected to an air source, and an oxygen outlet of the air separation device 1 being connected to an oxygen inlet of the biomass gasification device 2. Working principle: after the air separation device 1 is supplied with air, the air separation device 1 can separate oxygen from the air, and then supply the oxygen to the biomass gasification device 2 for oxidizing the biomass to obtain syngas.

[0032] In an embodiment, the air separation device 1 uses at least one of the following separation methods: cryogenic air separation method, molecular sieve air separation method, membrane separation method, and pressure swing adsorption method. That is, the air separation device 1 comprises at least one of a cryogenic air separator, a molecular sieve air separator, a membrane separator, and a pressure swing adsorber.

[0033] In an embodiment, the syngas preparation unit further comprises a second heat exchanger 8, a first flow divider 9, a first mixer 10, and a third heat exchanger 11. The second heat exchanger 8 is connected between an outlet of the dust removal device 3 and an inlet of the first flow divider 9. A first outlet of the first flow divider 9 is connected to a syngas inlet of the water gas shift reaction device 4. A second outlet of the first flow divider 9 is connected to a first inlet of the first mixer 10, and a reaction gas outlet of the water gas shift reaction device 4 is connected to a second inlet of the first mixer 10. The third heat exchanger 11 is connected between an outlet of the first mixer 10 and an inlet of the acid gas removal device 5. Working principle: the syngas generated by the biomass gasification device 2 is transported into the dust removal device 3 to remove ash in the syngas. After the ash is removed, the syngas is cooled by the second heat exchanger 8 and then enters the first flow divider 9 for flow division. Part of the syngas is sent into the first mixer 10, and the other part of the syngas enters the water gas shift reaction device 4 for water gas shift reaction. The syngas after hydrogenation is sent into the first mixer 10, mixed with the syngas without hydrogenation, and then sent into the third heat exchanger 11 for cooling. The cooled syngas is transported into the acid gas removal device 5 to remove excess carbon dioxide in the syngas.

[0034] In an embodiment, the methanol preparation unit comprises a first flash device 12, a second mixer 13, a first compressor 14, a fourth heat exchanger 15, a methanol synthesis device 16, a second flash device 17, and a second delivery pump 18. The gas inlet of the first flash device 12 is connected to the gas outlet of the acid gas removal device 5, the water outlet of the first flash device 12 is externally discharged, and the gas outlet of the first flash device 12 is connected to the first inlet of the second mixer 13. The outlet of the second mixer 13 is connected to the gas inlet of the first compressor 14. The fourth heat exchanger 15 is connected between the gas outlet of the first compressor 14 and the gas inlet of the methanol synthesis device 16. The methanol outlet of the methanol synthesis device 16 is connected to the liquid inlet of the second flash device 17. The gas outlet of the second flash device 17 is connected to the second inlet of the second mixer 13. The liquid outlet of the second flash device 17 is connected to the methanol purification and storage unit through the second delivery pump 18. The working principle is as follows: the synthesis gas passing through the acid gas removal device 5 is sent to the first flash device 12 to remove water, then is sent to the fourth heat exchanger 15 to be heated after being pressurized by the first compressor 14, then is sent to the methanol synthesis device 16 to synthesize methanol, the synthesized methanol is separated from the unreacted synthesis gas by the second flash device 17, the methanol is sent to the methanol purification and storage unit by the second delivery pump 18, and the remaining synthesis gas in the second flash device 17 is sent to the second mixer 13 for recycling.

[0035] In an embodiment, the methanol purification and storage unit comprises a methanol purification device 19 and a methanol storage tank 20. The liquid inlet of the methanol purification device 19 is connected to the methanol preparation unit (if the second delivery pump 18 is included, then to the second delivery pump 18). The liquid outlet of the methanol purification device 19 is connected to the methanol storage tank 20. The working principle is as follows: the dehydrated methanol output by the methanol preparation unit is sent to the methanol purification device 19 for purification, and the purified refined methanol is stored in the methanol storage tank 20.

[0036] In an embodiment, the methanol purification and storage unit comprises two groups of methanol purification devices 19, and the multiple groups of methanol purification devices 19 are connected in series.

[0037] In an embodiment, the formic acid preparation unit further comprises a third flash device 26. The carbon dioxide electro-reduction cell 21 is a three-chamber electrochemical device, comprising a cathode chamber 33, a center chamber 34 and an anode chamber 35. The cathode chamber 33 is provided with a carbon dioxide inlet and a carbon dioxide outlet, the carbon dioxide inlet of the cathode chamber 33 is connected to the carbon dioxide outlet of the acid gas removal device 5, and the carbon dioxide outlet of the cathode chamber 33 is connected to the carbon dioxide inlet of the cathode chamber 33. The center chamber 34 is provided with a first water source inlet and a formic acid aqueous solution outlet, and the formic acid aqueous solution outlet is connected to the formic acid purification and storage unit. The anode chamber 35 is provided with a second water source inlet and a water-oxygen mixture outlet, and the water-oxygen mixture outlet is connected to the gas inlet of the third flash device 26, the gas outlet of the third flash device 26 is connected to the oxygen inlet of the biomass gasification device 2, and the water outlet of the third flash device 26 is discharged. Working principle: The carbon dioxide collected by the acid gas removal device 5 is discharged into the cathode chamber 33 of the carbon dioxide electro-reduction cell 21 through the carbon dioxide outlet and the carbon dioxide inlet, and the center chamber 34 and the anode chamber 35 are fed with water. The carbon dioxide and water react to generate a formic acid-containing aqueous solution under the action of electric energy, the formic acid-containing aqueous solution is sent to the formic acid purification and storage unit through the formic acid aqueous solution outlet of the center chamber 34, the remaining carbon dioxide in the cathode chamber 33 is recycled by being mixed with newly added carbon dioxide through the carbon dioxide outlet and the carbon dioxide inlet, and the water and oxygen generated in the anode chamber 35 are sent to the third flash device 26 through the water-oxygen mixture outlet for dehydration. The dehydrated oxygen is sent to the oxygen inlet of the biomass gasification device 2 for utilization.

[0038] In an embodiment, the electric energy of the carbon dioxide electro-reduction cell 21 comes from renewable electricity.

[0039] In an embodiment, the formic acid purification and storage unit comprises a third mixer 22, a third delivery pump 23, a formic acid purification device 24 and a formic acid storage tank 25. The first inlet of the third mixer 22 is connected to the formic acid aqueous solution outlet, the outlet of the third mixer 22 is connected to the liquid inlet of the formic acid purification device 24 through the third delivery pump 23, the formic acid outlet of the formic acid purification device 24 is connected to the formic acid storage tank 25, and the residual liquid outlet of the formic acid purification device 24 is connected to the second inlet of the third mixer 22. Working principle: The formic acid-containing aqueous solution discharged from the carbon dioxide electro-reduction cell 21 enters the third mixer 22, is sent to the formic acid purification device 24 through the third delivery pump 23, the refined formic acid is stored in the formic acid storage tank 25, and the remaining solution in the formic acid purification device 24 is sent to the third mixer 22 for recycling.

[0040] In one embodiment, the formic acid purification and storage unit includes two sets of formic acid purification devices 24, with multiple sets of formic acid purification devices 24 arranged sequentially along the production direction. The inlet of the previous formic acid purification device 24 is connected to the third transfer pump 23, and the formic acid outlet of the previous formic acid purification device 24 is connected to the inlet of the next formic acid purification device 24. The formic acid outlet of the next formic acid purification device 24 is connected to the formic acid storage tank 25. The residual liquid outlet of the last-stage formic acid purification device 24 is connected to the second inlet of the third mixer 22, and the remaining solution in the last-stage formic acid purification device 24 is sent to the third mixer 22 for recycling. The residual liquid outlets of the remaining formic acid purification devices 24 are discharged externally.

[0041] In one embodiment, the formic acid purification apparatus 24 uses pressure swing distillation to separate and purify pure formic acid.

[0042] In one embodiment, the formic acid production line further includes an electrical suppression unit, which comprises a second distributor 27, a second compressor 28, a fifth heat exchanger 29, a carbon dioxide storage tank 30, a sixth heat exchanger 31, and a control valve 32. The inlet of the second distributor 27 is connected to the carbon dioxide outlet of the acid gas removal device 5, the first outlet of the second distributor 27 is connected to the carbon dioxide inlet of the formic acid purification device 24, and the second outlet of the second distributor 27 is connected to the inlet of the second compressor 28. The fifth heat exchanger 29 is connected between the outlet of the second compressor 28 and the inlet of the carbon dioxide storage tank 30. The sixth heat exchanger 31 is connected between the outlet of the carbon dioxide storage tank 30 and the control valve 32. The control valve 32 is connected to the carbon dioxide inlet of the formic acid purification device 24. Working principle: When power is insufficient, the carbon dioxide collected by the acid gas removal device 5 passes through the second distributor 27. Part of the carbon dioxide is sent to the carbon dioxide electroreduction cell 21, and the other part is compressed by the second compressor 28, cooled by the fifth heat exchanger 29, and then sent to the carbon dioxide storage tank 30 for storage. When power is sufficient, the control valve 32 can be opened to heat the carbon dioxide in the carbon dioxide storage tank 30 through the fifth heat exchanger 29 and then add it to the carbon dioxide storage tank 30. The amount of carbon dioxide entering the carbon dioxide electroreduction cell 21 is adjusted in real time according to the power fluctuations of the carbon dioxide electroreduction cell 21, effectively smoothing out power fluctuations. For example, when power is sufficient, more carbon dioxide is added, consuming more power; when power decreases, less carbon dioxide is added.

[0043] In one embodiment, the carbon dioxide storage tank 30 is a cryogenic liquid carbon dioxide storage tank.

[0044] In one embodiment, the production process of the biomass gasification to methanol co-production formic acid system is as follows: The syngas production unit utilizes biomass to produce syngas and carbon dioxide; The methanol production unit uses syngas to synthesize crude methanol; The methanol purification and storage unit separates and purifies pure methanol from the crude methanol containing synthesis gas and stores it; The formic acid preparation unit produces an aqueous solution containing formic acid by using carbon dioxide and electric energy; The formic acid purification and storage unit separates and purifies pure formic acid from the aqueous solution containing formic acid; The power smoothing unit adjusts the storage and supply relationship of carbon dioxide according to the fluctuation of electric power to smooth the fluctuation of electric power of the formic acid preparation unit.

[0045] Specifically, the biomass gasification methanol co-production formic acid system uses oxygen generated by the air separation device 1 to supply the biomass gasification device 2 to generate synthesis gas, and sequentially passes through the dust removal device 3, the water gas shift reaction device 4, the acid gas removal device 5, the flash device 12, the methanol synthesis device 16 and the methanol purification device 19 to generate refined methanol; the carbon dioxide collected by the acid gas removal device 5 is then introduced into the carbon dioxide electro-reduction tank 21, and after electrochemical reaction with water, a formic acid solution is generated, which is passed through the formic acid purification device 24 to generate refined formic acid; when the supply of electric power (such as renewable electric power) is insufficient, the excess carbon dioxide generated is stored in the carbon dioxide storage tank 30; when the supply of electric power is sufficient, the carbon dioxide stored in the carbon dioxide storage tank 30 is supplied into the carbon dioxide electro-reduction tank 21 to cope with the fluctuation of electric power (such as renewable electric power). By using the carbon dioxide generated in the process of biomass gasification methanol to prepare formic acid, the consumption of renewable electric power is realized, and the zero carbon emission of the synthesis methanol system is also realized, realizing green production of methanol and green production of formic acid, which has broad application prospects.

[0046] The principles and implementation modes of the present application are described by using specific examples in the present application, and the above examples are only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A biomass gasification system for methanol production and formic acid co-production, characterized in that, Including methanol production lines and formic acid production lines; The methanol production line includes a syngas preparation unit, a methanol preparation unit, and a methanol purification and storage unit. The syngas preparation unit includes a biomass gasification device, a dust removal device, a water-gas shift reaction device, and an acid gas removal device. The biomass gasification device includes an oxygen inlet, a biomass inlet, and a syngas outlet. The syngas outlet is connected to the inlet of the dust removal device. The water-gas shift reaction device includes a steam inlet, a syngas inlet, and a reaction gas outlet. The syngas inlet is connected to the outlet of the dust removal device. The reaction gas outlet and the outlet of the dust removal device are both connected to the inlet of the acid gas removal device. The outlet of the acid gas removal device is connected to the methanol preparation unit. The methanol preparation unit is connected to the methanol purification and storage unit. The formic acid production line includes a formic acid preparation unit and a formic acid purification and storage unit. The formic acid preparation unit includes a carbon dioxide electroreduction cell. The carbon dioxide inlet of the carbon dioxide electroreduction cell is connected to the carbon dioxide outlet of the acid gas removal device. The formic acid aqueous solution outlet of the carbon dioxide electroreduction cell is connected to the formic acid purification and storage unit.

2. The biomass gasification system for methanol production and formic acid co-production according to claim 1, characterized in that, The syngas preparation unit further includes a steam source, which includes a first delivery pump and a first heat exchanger. The inlet of the first delivery pump is connected to a water source, and the first heat exchanger is connected between the outlet of the first delivery pump and the steam inlet of the water-gas shift reaction device.

3. The biomass gasification system for methanol production and formic acid co-production according to claim 1, characterized in that, The syngas preparation unit also includes an air separation device, the air inlet of which supplies air, and the oxygen outlet of which is connected to the oxygen inlet of the biomass gasification device.

4. The biomass gasification system for methanol production and formic acid co-production according to claim 1 or 3, characterized in that, The syngas preparation unit further includes a first distributor, a first mixer, a second heat exchanger, and a third heat exchanger. The second heat exchanger is connected between the outlet of the dust removal device and the inlet of the first distributor. The first outlet of the first distributor is connected to the syngas inlet of the water-gas shift reaction device. The second outlet of the first distributor is connected to the first inlet of the first mixer. The reaction gas outlet of the water-gas shift reaction device is connected to the second inlet of the first mixer. The third heat exchanger is connected between the outlet of the first mixer and the inlet of the acid gas removal device.

5. The biomass gasification system for methanol production and formic acid co-production according to claim 1, characterized in that, The methanol preparation unit includes a first flash evaporator, a second mixer, a first compressor, a fourth heat exchanger, a methanol synthesis unit, a second flash evaporator, and a second delivery pump. The inlet of the first flash evaporator is connected to the outlet of the acid gas removal unit, the drain outlet of the first flash evaporator discharges externally, the outlet of the first flash evaporator is connected to the first inlet of the second mixer, the outlet of the second mixer is connected to the inlet of the first compressor, the fourth heat exchanger is connected between the outlet of the first compressor and the inlet of the methanol synthesis unit, the methanol outlet of the methanol synthesis unit is connected to the liquid inlet of the second flash evaporator, the outlet of the second flash evaporator is connected to the second inlet of the second mixer, and the liquid outlet of the second flash evaporator is connected to the methanol purification and storage unit via the second delivery pump.

6. The biomass gasification system for methanol production and formic acid co-production according to claim 1 or 5, characterized in that, The methanol purification and storage unit includes a methanol purification device and a methanol storage tank. The inlet of the methanol purification device is connected to the methanol preparation unit, and the outlet of the methanol purification device is connected to the methanol storage tank.

7. The biomass gasification system for methanol production and formic acid co-production according to claim 1, characterized in that, The formic acid preparation unit further includes a third flash evaporation device. The carbon dioxide electroreduction cell includes a cathode chamber, a central chamber, and an anode chamber. The cathode chamber is provided with a carbon dioxide inlet and a carbon dioxide outlet. The carbon dioxide inlet of the cathode chamber is connected to the carbon dioxide outlet of the acid gas removal device, and the carbon dioxide outlet of the cathode chamber is connected to the carbon dioxide inlet of the cathode chamber. The central chamber is provided with a first water source inlet and a formic acid aqueous solution outlet. The formic acid aqueous solution outlet is connected to the formic acid purification and storage unit. The anode chamber is provided with a second water source inlet and a water-oxygen mixture outlet. The water-oxygen mixture outlet is connected to the air inlet of the third flash evaporation device. The air outlet of the third flash evaporation device is connected to the oxygen inlet of the biomass gasification device, and the drain outlet of the third flash evaporation device discharges externally.

8. The biomass gasification system for methanol production and formic acid co-production according to claim 1 or 7, characterized in that, The formic acid purification and storage unit includes a third mixer, a third transfer pump, a formic acid purification device, and a formic acid storage tank. The first inlet of the third mixer is connected to the outlet of the formic acid aqueous solution. The outlet of the third mixer is connected to the inlet of the formic acid purification device through the third transfer pump. The formic acid outlet of the formic acid purification device is connected to the formic acid storage tank. The residual liquid outlet of the formic acid purification device is connected to the second inlet of the third mixer.

9. The biomass gasification system for methanol production and formic acid co-production according to claim 8, characterized in that, The formic acid purification and storage unit includes multiple sets of formic acid purification devices arranged sequentially along the production direction. The inlet of the formic acid purification device at the previous stage is connected to the third transfer pump, the formic acid outlet of the formic acid purification device at the previous stage is connected to the inlet of the formic acid purification device at the next stage, the formic acid outlet of the formic acid purification device at the next stage is connected to the formic acid storage tank, and the residual liquid outlet of the formic acid purification device at the tail stage is connected to the second inlet of the third mixer.

10. The biomass gasification system for methanol production and formic acid co-production according to claim 1 or 7, characterized in that, The formic acid production line also includes an electrical suppression unit, which comprises a second distributor, a second compressor, a fifth heat exchanger, a carbon dioxide storage tank, a sixth heat exchanger, and a control valve. The inlet of the second distributor is connected to the carbon dioxide outlet of the acid gas removal device, the first outlet of the second distributor is connected to the carbon dioxide inlet, and the second outlet of the second distributor is connected to the air inlet of the second compressor. The fifth heat exchanger is connected between the air outlet of the second compressor and the inlet of the carbon dioxide storage tank. The sixth heat exchanger is connected between the outlet of the carbon dioxide storage tank and the control valve. The control valve is connected to the carbon dioxide inlet of the carbon dioxide electroreduction cell.

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