System and method for preparing methanol through low-carbon co-conversion of coal and biomass

Abstract

The invention relates to a system and a method for preparing methanol through low-carbon co-conversion of coal and biomass, and relates to the technical field of energy and chemical industry. Comprising a coal and biomass co-gasification unit, a water-gas shift adsorption enhanced hydrogen production unit, a synthesis gas methanol production unit and a carbon dioxide hydrogenation methanol production unit, the mixed feed of coal and biomass enters the coal and biomass co-gasification unit; synthesis gas I generated by the coal and biomass co-gasification unit enters the water-gas shift adsorption enhanced hydrogen production unit and the synthesis gas methanol production unit; high-purity hydrogen generated by the water-gas shift adsorption enhanced hydrogen production unit enters the synthesis gas-to-methanol unit, and carbon dioxide generated by the water-gas shift adsorption enhanced hydrogen production unit enters the carbon dioxide hydrogenation-to-methanol unit; the synthesis gas-to-methanol unit is used for synthesizing a methanol product I; the carbon dioxide hydrogenation methanol preparation unit is used for synthesizing a methanol product II. According to the invention, the energy consumption and carbon dioxide emission in the gasification process and the carbon dioxide trapping process can be reduced, and the resource and energy utilization rate can be obviously improved.

Description

Technical Field

[0001] The present invention relates to the field of energy chemical technology, and in particular to a system and method for producing methanol through low-carbon co-conversion of coal and biomass. Background Art

[0002] Coal-to-methanol and chemicals using methanol as a transition platform are important components of modern new coal chemical industry, and are also key links in achieving clean and efficient utilization of coal with coal gasification as the core. At present, the traditional production of chemicals through coal gasification has the problems of low energy utilization, high energy consumption and high carbon emissions. The hydrogen-carbon ratio of coal is about 4:5, while the hydrogen-carbon ratio of coal chemicals such as methanol, olefins, liquid fuels and natural gas is about 2:1, 2:1, 2:1 and 3:1. The mismatch between carbon and hydrogen elements in coal and chemical products leads to carbon redundancy and high CO2 emissions in the coal chemical process. For example, in the coal-to-methanol process, since the hydrogen-carbon ratio of coal gasification synthesis gas is 0.7, a water-gas shift reaction is required to convert CO into H2. More than 50% of the carbon is converted into CO2 through the water-gas shift reaction and discharged into the atmosphere, and the CO2 emissions per unit methanol product are 3.8 to 4.3 tons. Energy conservation and emission reduction have become an important goal of the current coal-to-chemical industry.

[0003] The coal-to-methanol process includes an air separation unit, a coal gasification unit, an acid gas removal unit, a water-gas shift unit, a methanol synthesis and methanol distillation unit, and a CO2 geological storage unit. Among them, the air separation unit has a large energy consumption during oxygen separation. The shifted gas is mixed with the unshifted gas before entering the acid gas removal unit, resulting in a low CO2 concentration and high capture energy consumption in the acid gas removal unit. After the acid gas removal unit, the direct carbon emissions caused by each ton of methanol produced are as high as 2 tons, and this part of CO2 is geologically stored instead of being used.

[0004] Solar energy as a heat source for the system not only saves the air separation unit to reduce energy consumption, but also avoids the waste of elements caused by direct combustion of coal and reduces the pollution of the combustion byproduct CO2 to the synthesis gas. Co-gasification of biomass with coal in a certain proportion can not only make up for the shortage of coal resources, reduce the emission of CO2, but also improve the utilization rate of elements in the gasification process. The CO2 in-situ capture enhanced water-gas shift hydrogen production process can combine the synthesis gas preparation and gas separation steps, remove the CO2 produced by the water-gas shift reaction in situ by adding adsorbents, produce high-purity H2 in one step and enrich and recover pure CO2. CO2 participates in many chemical reactions as the main reactant. From the perspective of large-scale utilization, the CO2 hydrogenation to methanol reaction is one of the most valuable research and application methods. H2 can be obtained by electrolysis of water or industrial byproducts using green and clean energy such as solar energy or wind energy. By developing suitable process methods, coal and biomass can be converted into methanol in a low-carbon manner, which can not only reduce carbon emissions but also improve energy efficiency. Summary of the invention

[0005] In order to solve at least one technical problem in the background technology, the present invention provides a system and method for low-carbon co-conversion of coal and biomass to produce methanol, which helps to reduce energy consumption in the gasification process and the carbon dioxide capture process and reduce carbon dioxide emissions, thereby significantly improving resource and energy utilization.

[0006] To achieve the above-mentioned object, the present invention provides a system for producing methanol by low-carbon co-conversion of coal and biomass, comprising: a coal and biomass co-gasification unit, a water-gas shift adsorption enhanced hydrogen production unit, a synthesis gas to methanol unit and a carbon dioxide hydrogenation to methanol unit;

[0007] Coal and biomass are crushed and mixed by a mixing crusher, and the mixed feed enters the coal and biomass co-gasification unit; the synthesis gas I generated by the coal and biomass co-gasification unit enters the water-gas shift adsorption enhanced hydrogen production unit and the synthesis gas to methanol unit; the high-purity hydrogen produced by the water-gas shift adsorption enhanced hydrogen production unit enters the synthesis gas to methanol unit, and the carbon dioxide produced by the water-gas shift adsorption enhanced hydrogen production unit enters the carbon dioxide hydrogenation to methanol unit; the synthesis gas to methanol unit is used to synthesize methanol product I; the carbon dioxide hydrogenation to methanol unit is used to synthesize methanol product II.

[0008] Furthermore, the coal and biomass co-gasification unit includes a gasifier, a desulfurization tower, a convection heat exchanger, a gas-liquid separator and a splitter I; the gasifier is used to gasify the mixed feed to produce a crude synthesis gas; the desulfurization tower is used to remove hydrogen sulfide from the crude synthesis gas; the convection heat exchanger is used to cool the desulfurized synthesis gas; the gas-liquid separator is used to separate the unreacted water vapor in the synthesis gas after cooling to produce synthesis gas I; wherein the synthesis gas I is divided into two streams by the splitter I, one stream enters the synthesis gas to methanol unit as synthesis gas III, and the other stream enters the water gas shift adsorption enhanced hydrogen production unit as synthesis gas II and unreacted water vapor.

[0009] Furthermore, the water-gas shift adsorption enhanced hydrogen production unit includes a water-gas shift adsorption enhanced reactor and an adsorbent regeneration reactor; wherein, synthesis gas II enters the water-gas shift adsorption enhanced reactor to undergo a water-gas shift reaction with unreacted water vapor to produce hydrogen and carbon dioxide, the adsorbent reacts chemically with the generated carbon dioxide to capture the generated carbon dioxide, causing the equilibrium of the water-gas shift reaction to shift to the right, the adsorbed saturated adsorbent enters the adsorbent regeneration reactor for adsorbent regeneration reaction, the regenerated adsorbent circulates into the water-gas shift adsorption enhanced reactor for adsorption reaction, the reproduced carbon dioxide I is divided into two streams by diverter II, one stream is carbon dioxide II entering the coal and biomass co-gasification unit to undergo gasification reaction with the mixed feed, and the other stream is carbon dioxide III entering the carbon dioxide hydrogenation to methanol unit to produce methanol product; the high-purity hydrogen I produced by the water-gas shift adsorption enhanced hydrogen production unit is mixed with synthesis gas III by a mixer and then enters the synthesis gas to methanol unit.

[0010] Furthermore, the synthesis gas to methanol unit comprises a methanol synthesis reactor I, a high-pressure separator I, a pre-distillation tower and a methanol main distillation tower; wherein, the mixed synthesis gas enters the methanol synthesis reactor I to generate crude methanol, the product enters the high-pressure separator I to separate the unreacted gas, a part of which is circulated back to the methanol synthesis reactor I as the circulating reaction gas I, and a part of which is discharged as the purge gas I, the separated high-pressure separator liquid I enters the pre-distillation tower to separate the light component product, and then the crude methanol II in the tower bottom enters the methanol main distillation tower to obtain the methanol product I and wastewater I.

[0011] Furthermore, the carbon dioxide hydrogenation to methanol unit comprises a methanol synthesis reactor II, a high-pressure separator II, a low-pressure separator and a methanol distillation tower; wherein, carbon dioxide III enters the methanol synthesis reactor II to react with hydrogen II to generate crude methanol III, the product enters the high-pressure separator II to separate out unreacted circulating reaction gas II which is circulated back to the methanol synthesis reactor II, the separated high-pressure separator liquid II enters the low-pressure separator to separate out unreacted gas, a part of which is used as circulating reaction gas III to be circulated back to the methanol synthesis reactor II, and a part of which is discharged as purge gas II, and the separated low-pressure separator liquid enters the methanol distillation tower to obtain methanol product II and wastewater II.

[0012] A method for producing methanol by low-carbon co-conversion of coal and biomass comprises the following steps:

[0013] a): feeding coal and biomass into a mixer crusher to generate mixed feed through crushing and mixing;

[0014] b): The mixed feed produced in step a) enters the gasifier, and water vapor as a gasifying agent is added to produce a crude synthesis gas and ash. The crude synthesis gas enters the desulfurization tower. The desulfurized synthesis gas enters the convection heat exchanger for cooling and then enters the gas-liquid separator to obtain synthesis gas I and unreacted water vapor. The synthesis gas I enters the splitter and is divided into synthesis gas II and synthesis gas III;

[0015] c): The unreacted water vapor and synthesis gas II generated in step b) enter the water gas shift adsorption enhanced reactor to produce hydrogen I and carbon dioxide, the reaction temperature is 200-350°C, and the adsorbent enters to adsorb the generated carbon dioxide to form an adsorbent saturated adsorbent;

[0016] d): The synthesis gas III produced in step b) and the hydrogen I produced in step c) enter a mixer and are then sent to a methanol synthesis reactor I to produce crude methanol I, with a reaction temperature of 200-300° C.;

[0017] e): The adsorption saturated adsorbent produced in step c) enters the adsorbent regeneration reactor to produce adsorbent and release carbon dioxide I, and the adsorbent is recycled, and the reaction temperature is 350-450°C;

[0018] f): The crude methanol I produced in step d) enters the high-pressure separator I, and the obtained gas is recycled as the circulating reaction gas I to the methanol synthesis reactor I, and discharged as the purge gas I, as well as the high-pressure separator liquid I;

[0019] g): The high-pressure separator liquid I obtained in step f) enters a pre-distillation tower, and a light component product is obtained at the top of the tower, and crude methanol II is obtained at the bottom of the tower;

[0020] h): The crude methanol II obtained in step g) enters a methanol main distillation tower, and methanol product I is obtained at the top of the tower, and waste water I is obtained at the bottom of the tower;

[0021] i): The carbon dioxide I produced in step e) enters the splitter II and is divided into two streams to obtain carbon dioxide II and carbon dioxide III. The carbon dioxide II enters the gasifier as a gasifying agent to react with the mixed feed to produce a crude synthesis gas, and the carbon dioxide III enters the carbon dioxide hydrogenation to methanol unit;

[0022] j): The carbon dioxide III produced in step i) enters into the methanol synthesis reactor II together with the hydrogen II to obtain crude methanol III, and the reaction temperature is 200-300°C;

[0023] k): The crude methanol III produced in step j) enters the high-pressure separator II, and the obtained circulating reaction gas II is circulated back to the methanol synthesis reactor II and the obtained high-pressure separator liquid II;

[0024] l): The high-pressure separator liquid II obtained in step k) enters the low-pressure separator, and the obtained gas is recycled as the circulating reaction gas III and circulated back to the methanol synthesis reactor II, and the gas is discharged as the purge gas II, as well as the low-pressure separator liquid;

[0025] m): The low-pressure separator liquid obtained in step l) enters a methanol distillation tower, and methanol product II is obtained at the top of the tower, and waste water II is obtained at the bottom of the tower.

[0026] Furthermore, the gasification furnace in step b) is a fixed bed, a fluidized bed, or an entrained bed.

[0027] Furthermore, in step c), the adsorbent is one of magnesium oxide and calcium oxide.

[0028] Furthermore, the catalyst used in the methanol synthesis gas reactor I in step d) is one or a mixture of CuO, Al2O3, and ZnO.

[0029] The beneficial effects of the present invention are:

[0030] 1) Solar energy as the heat source of the system not only eliminates the need for an air separation unit to reduce energy consumption, but also avoids the waste of elements caused by direct combustion of coal and reduces the pollution of the combustion by-product CO2 to the synthesis gas.

[0031] 2) Co-gasification of biomass with coal in a certain proportion can make up for the shortage of coal resources, reduce the emission of gaseous pollutants in the coal utilization process, especially reduce the emission of CO2, improve the efficiency of coal gasification reaction and promote the effective utilization of elements such as C, H, and O in the raw materials.

[0032] 3) Compared with the high energy consumption of the traditional solvent absorption method, the CO2 in-situ capture enhanced water gas shift hydrogen production process can break through the thermodynamic and kinetic limitations of the traditional water gas shift hydrogen production process, combine the synthesis gas preparation and gas separation steps, and remove the CO2 produced by the water gas shift reaction in situ by adding adsorbents, thereby improving the conversion rate and selectivity, producing high-purity H2 in one step and enriching and recovering pure CO2.

[0033] 4) Chemical utilization of CO2 to produce methanol can reduce CO2 emissions on the one hand and increase methanol production on the other. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a system structure diagram of the present invention.

[0035] In the figure: 1, coal; 2, biomass; 3, mixed feed; 4, water vapor; 5, ash; 6, crude synthesis gas; 7, desulfurized synthesis gas; 8, hydrogen sulfide; 9, synthesis gas after cooling; 10, synthesis gas I; 11, unreacted water vapor; 12, synthesis gas II; 13, synthesis gas III; 14, hydrogen I; 15, adsorbent; 16, adsorption saturated adsorbent; 17, carbon dioxide I; 18, mixed synthesis gas; 19, crude methanol I; 20, circulating reaction gas I; 21, purge gas I; 22, high pressure separator liquid I; 23, light component product; 24, crude methanol II; 25, methanol product I; 26, wastewater I; 27, carbon dioxide II; 28, carbon dioxide III; 29, hydrogen II; 30, crude methanol III; 3 1. High-pressure separator liquid II; 32. Circulating reaction gas II; 33. Circulating reaction gas III, 34. Purge gas II; 35. Low-pressure separator liquid; 36. Methanol product II; 37. Wastewater II; B1. Mixer crusher; B2. Gasifier; B3. Desulfurization tower; B4. Convective heat exchanger; B5. Gas-liquid separator; B6. Diverter I; B7 Water-gas shift adsorption enhanced reactor; B8. Adsorbent regeneration reactor; B9. Mixer; B10. Methanol synthesis reactor I; B11. High-pressure separator I; B12. Pre-distillation tower; B13. Methanol main distillation tower; B14. Diverter II; B15. Methanol synthesis reactor II; B16. High-pressure separator II; B17. Low-pressure separator; B18. Methanol distillation tower. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0038] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0039] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0040] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] like Figure 1As shown, the present invention provides a system for producing methanol by low-carbon co-conversion of coal and biomass, comprising: a coal and biomass co-gasification unit, a water-gas shift adsorption enhanced hydrogen production unit, a synthesis gas to methanol unit and a carbon dioxide hydrogenation to methanol unit;

[0042] Coal 1 and biomass 2 are crushed and mixed by a mixing crusher B1, and the mixed feed 3 enters the coal and biomass co-gasification unit; the synthesis gas Ⅰ10 generated by the coal and biomass co-gasification unit enters the water gas shift adsorption enhanced hydrogen production unit and the synthesis gas to methanol unit; the high-purity hydrogen produced by the water gas shift adsorption enhanced hydrogen production unit enters the synthesis gas to methanol unit, and the carbon dioxide produced by the water gas shift adsorption enhanced hydrogen production unit enters the carbon dioxide hydrogenation to methanol unit; the synthesis gas to methanol unit is used to synthesize methanol product Ⅰ25; the carbon dioxide hydrogenation to methanol unit is used to synthesize methanol product Ⅱ36.

[0043] The coal and biomass co-gasification unit includes a gasifier B2, a desulfurization tower B3, a convection heat exchanger B4, a gas-liquid separator B5 and a splitter ⅠB6; the gasifier B2 is used to gasify the mixed feed 3 to produce a crude synthesis gas 6; the desulfurization tower B3 is used to remove hydrogen sulfide from the crude synthesis gas 6; the convection heat exchanger B4 is used to cool the desulfurized synthesis gas 7; the gas-liquid separator B5 is used to separate the unreacted water vapor 11 in the synthesis gas 9 after cooling to produce synthesis gas Ⅰ10; wherein the synthesis gas Ⅰ10 is divided into two streams by the splitter ⅠB6, one stream enters the synthesis gas to methanol unit as synthesis gas Ⅲ13, and the other stream enters the water gas shift adsorption enhanced hydrogen production unit as synthesis gas Ⅱ12 and the unreacted water vapor 11.

[0044] The water-gas shift adsorption enhanced hydrogen production unit includes a water-gas shift adsorption enhanced reactor B7 and an adsorbent regeneration reactor B8; wherein, the synthesis gas II 12 enters the water-gas shift adsorption enhanced reactor B7 and undergoes a water-gas shift reaction with the unreacted water vapor 11 to produce hydrogen and carbon dioxide, the adsorbent 15 reacts chemically with the generated carbon dioxide to capture the generated carbon dioxide, causing the water-gas shift reaction equilibrium to shift to the right, the adsorbed saturated adsorbent 16 enters the adsorbent regeneration reactor B8 for the adsorbent regeneration reaction, the regenerated adsorbent 15 circulates into the water-gas shift adsorption enhanced reactor B7 for the adsorption reaction, the reproduced carbon dioxide I 17 is divided into two streams by the splitter IIB14, one stream is carbon dioxide II 27 that enters the coal and biomass co-gasification unit to undergo a gasification reaction with the mixed feed 3, and the other stream is carbon dioxide III 28 that enters the carbon dioxide hydrogenation to methanol unit to produce a methanol product; the high-purity hydrogen I 14 produced by the water-gas shift adsorption enhanced hydrogen production unit is mixed with the synthesis gas III 13 by the mixer B9 and then enters the synthesis gas to methanol unit.

[0045] The synthesis gas to methanol unit comprises a methanol synthesis reactor ⅠB10, a high-pressure separator ⅠB11, a pre-distillation tower B12 and a methanol main distillation tower B13; wherein, a mixed synthesis gas 18 enters the methanol synthesis reactor ⅠB10 to generate crude methanol 19, the product enters the high-pressure separator ⅠB11 to separate the unreacted gas, a part of which is circulated back to the methanol synthesis reactor ⅠB10 as a circulating reaction gas Ⅰ20, and a part of which is discharged as a purge gas Ⅰ21, the separated high-pressure separator liquid Ⅰ22 enters the pre-distillation tower B12 to separate the light component product 23, and then the crude methanol Ⅱ24 ​​in the tower bottom enters the methanol main distillation tower B13 to obtain a methanol product Ⅰ25 and wastewater Ⅰ26.

[0046] The carbon dioxide hydrogenation to methanol unit comprises a methanol synthesis reactor ⅡB15, a high-pressure separator ⅡB16, a low-pressure separator B17 and a methanol distillation tower B18; wherein, carbon dioxide III28 enters the methanol synthesis reactor ⅡB15 to react with hydrogen II29 to generate crude methanol III30, the product enters the high-pressure separator ⅡB16 to separate out unreacted circulating reaction gas Ⅱ32 which is circulated back to the methanol synthesis reactor ⅡB15, the separated high-pressure separator liquid Ⅱ31 enters the low-pressure separator B17 to separate out unreacted gas, a part of which is used as circulating reaction gas III33 to be circulated back to the methanol synthesis reactor ⅡB15, and a part of which is discharged as purge gas Ⅱ34, and the separated low-pressure separator liquid 35 enters the methanol distillation tower B18 to obtain methanol product Ⅱ36 and wastewater Ⅱ37.

[0047] The present invention adopts the co-gasification of coal and biomass, makes full use of the hydrogen-rich resources in biomass, and reduces the consumption of non-renewable energy coal. Solar energy is used as the heat source of the system, which not only saves the air separation unit and reduces energy consumption, but also effectively utilizes more biomass and coal raw materials by reducing in-situ coal combustion. In addition, the water-gas shift adsorption enhanced hydrogen production technology can produce high-purity hydrogen in one step without the water-gas shift unit and acid gas removal unit in the traditional coal-to-methanol process, and capture carbon dioxide at one time, reducing the capture energy consumption. In addition, the production of methanol from carbon dioxide can reduce carbon emissions and increase methanol production. The method significantly improves resource and energy utilization and reduces carbon emissions.

[0048] The present invention also provides a method for producing methanol by low-carbon co-conversion of coal and biomass, comprising the following steps:

[0049] a): coal and biomass are fed into a mixer crusher B1, and mixed and crushed to produce a mixed feed 3, wherein the coal and biomass in the obtained mixed feed are 0-100wt% and 0-100wt% respectively;

[0050] b): The mixed feed 3 produced in step a) enters the gasifier, and the gasifying agent water vapor 4 is added, and a crude synthesis gas 6 and ash 5 are produced by gasification reaction. The crude synthesis gas 6 enters the desulfurization tower to remove hydrogen sulfide 8, and the desulfurized synthesis gas 7 enters the convection heat exchanger B4 for cooling and then enters the gas-liquid separator B5 for water vapor separation to obtain synthesis gas I10 and unreacted water vapor 11. The synthesis gas I10 enters the splitter B6 and is divided into synthesis gas II12 and synthesis gas III13, wherein the gasifier is a fixed bed, fluidized bed, or entrained flow bed, wherein the temperature of the gasifier is 700-1000°C;

[0051] c): The unreacted water vapor 11 and the synthesis gas II 12 generated in step b) enter the water gas shift adsorption enhanced reactor to undergo a water gas shift reaction to produce hydrogen I 14 and carbon dioxide, the reaction temperature is 200-350°C, and the adsorbent 15 enters to adsorb the generated carbon dioxide to form an adsorbed saturated adsorbent 16, wherein the adsorbent is one of magnesium oxide and calcium oxide;

[0052] d): The synthesis gas III13 produced in step b) and the hydrogen I14 produced in step c) enter the mixer B9 and are sent to the methanol synthesis reactor IB10 to produce crude methanol I19. The reaction temperature is 200-300°C. The catalyst used in the methanol synthesis gas reactor IB10 is a mixture of CuO, Al2O3, and ZnO. Preferably, the weight ratio of each component of the mixed catalyst is: CuO 20-75 parts, ZnO 15-50 parts, Al2O3 50 parts. The single-pass conversion rate of the mixed synthesis gas 18 is 0-100%.

[0053] e): The adsorbent saturated adsorbent 16 produced in step c) enters the adsorbent regeneration reactor B8 to be heated and regenerated to produce adsorbent 15 and release carbon dioxide I17. The adsorbent 15 is recycled, and the reaction temperature is 350-450°C;

[0054] f): The crude methanol I19 produced in step d) enters the high-pressure separator IB11, and one of the obtained gases is the circulating reaction gas I20 which is circulated back to the methanol synthesis reactor IB10, and the other is the purge gas I21 which is discharged, and the high-pressure separator liquid I22;

[0055] g): The high-pressure separator liquid I22 obtained in step f) enters the pre-distillation tower B12, and a light component product 23 is obtained at the top of the tower, and crude methanol II24 is obtained at the bottom of the tower;

[0056] h): The crude methanol II 24 obtained in step g) enters the methanol main distillation tower B13, and a methanol product I 25 is obtained at the top of the tower, and waste water I 26 is obtained at the bottom of the tower, wherein the methanol mass fraction in the methanol product I 25 is greater than 99.9%;

[0057] i): The carbon dioxide I17 produced in step e) enters the splitter IIB14 and is divided into two streams to obtain carbon dioxide II27 and carbon dioxide III28. The carbon dioxide II27 enters the gasifier B2 as a gasifying agent to react with the mixed feed to produce a crude synthesis gas, and the carbon dioxide III28 enters the carbon dioxide hydrogenation to produce methanol unit;

[0058] j): The carbon dioxide III 28 produced in step i) is fed together with hydrogen II 29 into a methanol synthesis reactor IIB15 to obtain crude methanol III 30, wherein the reaction temperature is 200-300°C;

[0059] k): The crude methanol III30 produced in step j) enters the high-pressure separator II B16, and the obtained circulating reaction gas II32 is circulated back to the methanol synthesis reactor II B15 and the obtained high-pressure separator liquid II31;

[0060] l): The high-pressure separator liquid II31 obtained in step k) enters the low-pressure separator B17, and the obtained gas is recycled as the circulating reaction gas III33 and circulated back to the methanol synthesis reactor IIB15, and the gas is discharged as the purge gas II34, and the low-pressure separator liquid 35;

[0061] m): The low-pressure separator liquid 35 obtained in step l) enters the methanol distillation tower B18, and a methanol product II 36 is obtained at the top of the tower, and waste water II 37 is obtained at the bottom of the tower, wherein the methanol mass fraction in the methanol product II 36 is greater than 99.9%.

[0062] The present invention utilizes solar energy as the heat source of the system, which not only eliminates the air separation unit to reduce energy consumption, but also avoids the waste of elements caused by direct combustion of coal, and reduces the pollution of the combustion byproduct CO2 to the synthesis gas. Co-gasification of biomass with coal in a certain proportion can not only make up for the shortage of coal resources, reduce the emission of gaseous pollutants in the coal utilization process, especially reduce the emission of CO2, improve the efficiency of coal gasification reaction and promote the effective utilization of elements such as C, H, and O in the raw materials. Compared with the high energy consumption of the traditional solvent absorption method, the CO2 in-situ capture and enhanced water-gas shift hydrogen production process can break through the thermodynamic and kinetic limitations of the traditional water-gas shift hydrogen production process, combine the synthesis gas preparation and gas separation steps, and remove the CO2 produced by the water-gas shift reaction in situ by adding an adsorbent, thereby improving the conversion rate and selectivity, producing high-purity H2 in one step and enriching and recovering pure CO2. Chemical utilization of CO2 to produce methanol can reduce the emission of CO2 on the one hand, and increase the yield of methanol on the other hand.

[0063] Embodiment 1:

[0064] like Figure 1 As shown in the figure, 6t / h of coal 1 and 4t / h of biomass are fed into the mixer crusher B1 and then into the gasifier B2. The temperature of the gasifier is 900℃, and the gasifier steam 4 is 7t / h, generating 105,000m3 / h of crude synthesis gas 6, the crude synthesis gas 6 is desulfurized by desulfurization tower B3 to remove hydrogen sulfide 8, and then enters the counter-flow heat exchanger B4 to 101,800 m 3 / h desulfurized synthesis gas 7 is cooled and the gas-liquid separator B5 is used to achieve 24,600 m 3 / h after cooling, the unreacted water vapor 11 in the synthesis gas 9 is separated to produce 8132m 3 / h of synthesis gas Ⅰ10. The synthesis gas Ⅰ10 is divided into two streams, 61% of which enters the synthesis gas to methanol unit, and the rest and unreacted water vapor 11 enter the water gas shift adsorption enhanced hydrogen production unit. 3171m 3 / h of synthesis gas II 12 enters the water-gas shift adsorption enhanced reactor B7 and undergoes water-gas shift reaction with 2.25t / h of unreacted water vapor 11 to produce 17,100m 3 / h of hydrogen, adsorbent 15 adsorbs saturated carbon dioxide and enters adsorbent regeneration reactor B8 for adsorbent regeneration reaction, and the regenerated adsorbent circulates into water-gas shift adsorption enhanced reactor B7. The regenerated carbon dioxide I 178.8t / h is divided into two streams, of which 2.5t / h enters the coal and biomass co-gasification unit to react with the mixed feed 3 for gasification, and the remaining 6.3t / h enters the carbon dioxide hydrogenation to methanol unit to produce 4.3t / h of methanol product. The 17,100m 3 / h high-purity hydrogen and 4961m 3 / h of synthesis gas III13 is mixed and then enters the synthesis gas to methanol unit to produce 9.6t / h of methanol product.

[0065] Embodiment 2:

[0066] like Figure 1 As shown in the figure, 5t / h of coal 1 and 5t / h of biomass are fed into the mixer crusher B1 and then into the gasifier B2. The temperature of the gasifier is 900℃, and the gasifier steam 4 is 7t / h, generating 103,100m 3 / h of crude synthesis gas 6, the crude synthesis gas 6 is desulfurized by desulfurization tower B3 to remove hydrogen sulfide 8, and then enters the counter-heat exchanger B4 to 100,600 m 3 / h desulfurized synthesis gas 7 is cooled and the gas-liquid separator B5 is used to achieve 23,900 m 3 / h after cooling, the unreacted water vapor 11 in the synthesis gas 9 is separated to produce 7911m 3 / h of synthesis gas Ⅰ10. The synthesis gas Ⅰ10 is divided into two streams, 62% of which enters the synthesis gas to methanol unit, and the rest and unreacted water vapor 11 enter the water gas shift adsorption enhanced hydrogen production unit. 3006m 3 / h of synthesis gas II 12 enters the water-gas shift adsorption enhanced reactor B7 and reacts with 2.5t / h of unreacted water vapor 11 to produce 17,800m 3 / h of hydrogen, adsorbent 15 adsorbs saturated carbon dioxide and enters adsorbent regeneration reactor B8 for adsorbent regeneration reaction, and the regenerated adsorbent circulates into water-gas shift adsorption enhanced reactor B7. The regenerated carbon dioxide I 178.09t / h is divided into two streams, of which 2t / h enters the coal and biomass co-gasification unit to undergo gasification reaction with mixed feed 3, and the remaining 6.09t / h enters the carbon dioxide hydrogenation to methanol unit to produce 5.7t / h of methanol product. The 17,800m 3 / h high purity hydrogen and 4905m 3 / h of synthesis gas III13 is mixed and then enters the synthesis gas to methanol unit to produce 9.2t / h of methanol product.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A system for producing methanol by low-carbon co-conversion of coal and biomass, characterized in that: include: Coal and biomass co-gasification unit, water gas shift adsorption enhanced hydrogen production unit, synthesis gas to methanol unit and carbon dioxide hydrogenation to methanol unit; Coal (1) and biomass (2) are crushed and mixed by a mixing crusher (B1), and the mixed feed (3) enters the coal and biomass co-gasification unit; the synthesis gas I (10) generated by the coal and biomass co-gasification unit enters the water gas shift adsorption enhanced hydrogen production unit and the synthesis gas to methanol unit; the high-purity hydrogen produced by the water gas shift adsorption enhanced hydrogen production unit enters the synthesis gas to methanol unit, and the carbon dioxide produced by the water gas shift adsorption enhanced hydrogen production unit enters the carbon dioxide hydrogenation to methanol unit; the synthesis gas to methanol unit is used to synthesize methanol product I (25); the carbon dioxide hydrogenation to methanol unit is used to synthesize methanol product II (36).

2. A system for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 1, characterized in that: The coal and biomass co-gasification unit comprises a gasifier (B2), a desulfurization tower (B3), a convection heat exchanger (B4), a gas-liquid separator (B5) and a splitter I (B6); the gasifier (B2) is used to gasify the mixed feed (3) to produce a crude synthesis gas (6); the desulfurization tower (B3) is used to remove hydrogen sulfide from the crude synthesis gas (6); the convection heat exchanger (B4) is used to cool the desulfurized synthesis gas (7); the gas-liquid separator (B5) is used to separate the unreacted water vapor (11) in the synthesis gas (9) after cooling to produce synthesis gas I (10); wherein the synthesis gas I (10) is divided into two streams by the splitter I (B6), one stream is used as synthesis gas III (13) to enter the synthesis gas to methanol unit, and the other stream is used as synthesis gas II (12) and the unreacted water vapor (11) to enter the water gas shift adsorption enhanced hydrogen production unit.

3. A system for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 2, characterized in that: The water-gas shift adsorption enhanced hydrogen production unit comprises a water-gas shift adsorption enhanced reactor (B7) and an adsorbent regeneration reactor (B8); wherein, the synthesis gas II (12) enters the water-gas shift adsorption enhanced reactor (B7) and reacts with the unreacted water vapor (11) to produce hydrogen and carbon dioxide, the adsorbent (15) reacts chemically with the produced carbon dioxide to capture the produced carbon dioxide, causing the water-gas shift reaction equilibrium to shift to the right, and the adsorbent (16) enters the adsorbent regeneration reactor (B8) to undergo a regeneration reaction of the adsorbent, and the regenerated adsorbent The additive (15) is circulated into the water-gas shift adsorption enhanced reactor (B7) for adsorption reaction, and the re-produced carbon dioxide I (17) is divided into two streams through the splitter II (B14). One stream is carbon dioxide II (27) which enters the coal and biomass co-gasification unit to undergo gasification reaction with the mixed feed (3), and the other stream is carbon dioxide III (28) which enters the carbon dioxide hydrogenation to methanol unit to produce methanol product; the high-purity hydrogen I (14) produced by the water-gas shift adsorption enhanced hydrogen production unit is mixed with the synthesis gas III (13) through the mixer (B9) and then enters the synthesis gas to methanol unit.

4. A system for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 3, characterized in that: The synthesis gas to methanol unit comprises a methanol synthesis reactor I (B10), a high-pressure separator I (B11), a pre-distillation tower (B12) and a methanol main distillation tower (B13); wherein, a mixed synthesis gas (18) enters the methanol synthesis reactor I (B10) to generate crude methanol (19), the product enters the high-pressure separator I (B11) to separate out unreacted gas, a part of which is circulated back to the methanol synthesis reactor I (B10) as a circulating reaction gas I (20), and a part of which is discharged as a purge gas I (21), the separated high-pressure separator liquid I (22) enters the pre-distillation tower (B12) to separate out a light component product (23), and then the crude methanol II (24) in the tower kettle enters the methanol main distillation tower (B13) to obtain a methanol product I (25) and wastewater I (26).

5. A system and method for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 4, characterized in that: The carbon dioxide hydrogenation methanol unit comprises a methanol synthesis reactor II (B15), a high-pressure separator II (B16), a low-pressure separator (B17) and a methanol distillation tower (B18); wherein carbon dioxide III (28) enters the methanol synthesis reactor II (B15) and reacts with hydrogen II (29) to generate crude methanol III (30); the product enters the high-pressure separator II (B16) to separate out unreacted circulating reaction gas II (32) which is circulated back to the methanol synthesis reactor II (B15); the separated high-pressure separator liquid II (31) enters the low-pressure separator (B17) to separate out unreacted gas, a part of which is circulated back to the methanol synthesis reactor II (B15) as circulating reaction gas III (33) and a part of which is discharged as purge gas II (34); the separated low-pressure separator liquid (35) enters the methanol distillation tower (B18) to obtain methanol product II (36) and wastewater II (37).

6. A method for producing methanol by low-carbon co-conversion of coal and biomass, characterized in that: The steps include: a): coal (1) and biomass (2) are fed into a mixer-crusher (B1), and mixed and crushed to produce a mixed feed (3); b): The mixed feed (3) produced in step a) enters the gasifier (B2), and the gasifying agent water vapor (4) is added to produce a crude synthesis gas (6) and ash (5). The crude synthesis gas (6) enters the desulfurization tower. The desulfurized synthesis gas (7) enters the convection heat exchanger (B4) for cooling and then enters the gas-liquid separator (B5) to obtain synthesis gas I (10) and unreacted water vapor (11). The synthesis gas I (10) enters the splitter (B6) to be divided into synthesis gas II (12) and synthesis gas III (13); c): The unreacted water vapor (11) and the synthesis gas II (12) generated in step b) enter the water gas shift adsorption enhanced reactor to produce hydrogen I (14) and carbon dioxide, the reaction temperature is 200-350° C., and the adsorbent (15) enters to adsorb the generated carbon dioxide to form an adsorbent saturated adsorbent (16); d): The synthesis gas III (13) produced in step b) and the hydrogen I (14) produced in step c) enter the mixer (B9) and are then sent to the methanol synthesis reactor I (B10) to produce crude methanol I (19), and the reaction temperature is 200-300°C; e): The adsorption saturated adsorbent (16) produced in step c) enters the adsorbent regeneration reactor (B8) to produce adsorbent (15) and release carbon dioxide I (17), and the adsorbent (15) is recycled, and the reaction temperature is 350-450°C; f): The crude methanol I (19) produced in step d) enters the high-pressure separator I (B11), and the obtained gas is recycled as the circulating reaction gas I (20) to the methanol synthesis reactor I (B10), and the obtained gas is discharged as the purge gas I (21), and the high-pressure separator liquid I (22); g): The high-pressure separator liquid I (22) obtained in step f) enters a pre-distillation tower (B12), and a light component product (23) is obtained at the top of the tower, and crude methanol II (24) is obtained at the bottom of the tower; h): The crude methanol II (24) obtained in step g) enters a methanol main distillation tower (B13), and a methanol product I (25) is obtained at the top of the tower, and waste water I (26) is obtained at the bottom of the tower; i): The carbon dioxide I (17) produced in step e) enters the splitter II (B14) and is divided into two streams to obtain carbon dioxide II (27) and carbon dioxide III (28). The carbon dioxide II (27) enters the gasifier (B2) as a gasifying agent to react with the mixed feed to produce a crude synthesis gas, and the carbon dioxide III (28) enters the carbon dioxide hydrogenation to produce methanol unit; j): The carbon dioxide III (28) produced in step i) is fed together with hydrogen II (29) into a methanol synthesis reactor II (B15) to obtain crude methanol III (30), and the reaction temperature is 200-300°C; k): The crude methanol III (30) produced in step j) enters the high-pressure separator II (B16), and the obtained circulating reaction gas II (32) is circulated back to the methanol synthesis reactor II (B15) and the obtained high-pressure separator liquid II (31); l): The high-pressure separator liquid II (31) obtained in step k) enters the low-pressure separator (B17), and the obtained gas is a circulating reaction gas III (33) that is circulated back to the methanol synthesis reactor II (B15), and a purge gas II (34) that is discharged, as well as the low-pressure separator liquid (35); m): The low-pressure separator liquid (35) obtained in step l) enters a methanol distillation tower (B18), and methanol product II (36) is obtained at the top of the tower, and waste water II (37) is obtained at the bottom of the tower.

7. The method for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 6, characterized in that: The gasification furnace in step b) is a fixed bed, a fluidized bed or an entrained bed.

8. The method for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 6, characterized in that: In the step c), the adsorbent is one of magnesium oxide and calcium oxide.

9. The method for producing methanol by low-carbon co-conversion of coal and biomass as claimed in claim 6, characterized in that: The catalyst used in the methanol synthesis gas reactor I in step d) is one or a mixture of CuO, Al2O3, and ZnO.

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