System and method for co-conversion of coal and biomass to methanol with low carbon

Abstract

The present application relates to a coal and biomass low-carbon co-conversion methanol system and method, and relates to the technical field of energy chemical industry. The system comprises a coal and biomass co-gasification unit, a water-gas shift adsorption enhanced hydrogen production unit, a syngas 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; the syngas I generated by the coal and biomass co-gasification unit enters the water-gas shift adsorption enhanced hydrogen production unit and the syngas methanol production unit; the high-purity hydrogen generated by the water-gas shift adsorption enhanced hydrogen production unit enters the syngas methanol production unit, and the carbon dioxide generated by the water-gas shift adsorption enhanced hydrogen production unit enters the carbon dioxide hydrogenation methanol production unit; the syngas methanol production unit is used for synthesizing methanol product I; and the carbon dioxide hydrogenation methanol production unit is used for synthesizing methanol product II. The present application helps to reduce the energy consumption of the gasification process and the carbon dioxide capture process and the carbon dioxide emission, and significantly improves the resource and energy utilization rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy and chemical industry, in particular to a system and method for low-carbon co-conversion of coal and biomass into methanol. BACKGROUND

[0002] Methanol production from coal and chemicals based on methanol as an over-platform is an important part of modern new coal chemical industry, and is also a key link to realize clean and efficient utilization of coal with coal gasification as the core. At present, the traditional chemical production from coal gasification has the problems of low energy utilization rate, high energy consumption and large carbon emission. 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 of carbon and hydrogen elements in coal and chemical products leads to carbon redundancy and high CO2 emission in the process of coal chemical industry. For example, in the process of coal-to-methanol, the hydrogen-carbon ratio of coal gasification synthesis gas is 0.7, and water-gas shift reaction is needed to convert CO into H2. More than 50% of carbon is converted into CO2 and discharged into the atmosphere through water-gas shift reaction, and the CO2 emission per unit of methanol product is 3.8-4.3 tons. Energy saving and emission reduction has become an important goal of the current coal 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 rectification unit, and a CO2 geological sequestration unit. Among them, the air separation unit has large energy consumption during oxygen separation. The shift gas is mixed with the unshifted gas before entering the acid gas removal unit, resulting in low CO2 concentration and high capture energy consumption in the acid gas removal unit. After the acid gas removal unit, the direct carbon emission per ton of methanol produced is as high as 2t, and this part of CO2 is sequestrated without being utilized.

[0004] Solar energy as a system heat source 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 combustion byproduct CO2 to synthesis gas. Co-gasification of biomass with coal in a certain proportion can not only make up for the shortage of coal resources and reduce CO2 emissions, but also improve the element utilization rate in the gasification process. CO2 in-situ capture enhanced water-gas shift process can combine synthesis gas preparation and gas separation steps, remove CO2 generated by water-gas shift reaction in-situ by adding adsorbent, and produce high-purity H2 in one step and recover pure CO2. CO2 as the main reactant participates in many chemical reactions. From the perspective of large-scale utilization, CO2 hydrogenation to methanol is one of the most valuable ways for research and application. H2 can be obtained by electrolysis of water using solar or wind energy or industrial byproducts. By developing a suitable process, coal and biomass can be low-carbon converted into methanol, which not only reduces carbon emissions, but also improves energy efficiency. SUMMARY

[0005] To solve at least one technical problem in the background art, the present application provides a system and method for co-conversion of coal and biomass with low carbon to produce methanol, which helps to reduce the energy consumption of the gasification process and the carbon dioxide capture process, and reduce the emission of carbon dioxide, and significantly improve the utilization rate of resources and energy.

[0006] To achieve the above purpose, the present application provides a system for co-conversion of coal and biomass with low carbon to produce methanol, comprising: a coal and biomass co-gasification unit, a water-gas shift adsorption enhanced hydrogen production unit, a syngas to methanol unit, and a carbon dioxide hydrogenation to methanol unit.

[0007] The coal and biomass are crushed and mixed by a mixing crusher, and the mixed feed is fed into the coal and biomass co-gasification unit; the syngas I generated by the coal and biomass co-gasification unit enters the water-gas shift adsorption enhanced hydrogen production unit and the syngas to methanol unit; the high-purity hydrogen produced by the water-gas shift adsorption enhanced hydrogen production unit enters the syngas 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 syngas 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] Further, the coal and biomass co-gasification unit comprises a gasifier, a desulfurization tower, a convection heat exchanger, a gas-liquid separator, and a flow divider I; the gasifier is used to gasify the mixed feed to produce crude syngas; the desulfurization tower is used to remove hydrogen sulfide from the crude syngas; the convection heat exchanger is used to cool the desulfurized syngas; the gas-liquid separator is used to separate the unreacted steam in the cooled syngas to produce syngas I; wherein the syngas I is divided into two streams by the flow divider I, one stream enters the syngas to methanol unit as syngas III, and the other stream enters the water-gas shift adsorption enhanced hydrogen production unit as syngas II together with unreacted steam.

[0009] Further, the water-gas shift adsorption enhanced hydrogen production unit comprises a water-gas shift adsorption enhanced reactor and an adsorbent regeneration reactor; wherein, the syngas II enters the water-gas shift adsorption enhanced reactor to undergo a water-gas shift reaction with unreacted steam to produce hydrogen and carbon dioxide, the adsorbent chemically reacts with the produced carbon dioxide to capture the produced carbon dioxide, causing the water-gas shift reaction to shift to the right, the adsorbent saturated with adsorption enters the adsorbent regeneration reactor to undergo a regeneration reaction, the regenerated adsorbent circulates into the water-gas shift adsorption enhanced reactor to undergo an adsorption reaction, and the produced carbon dioxide I is divided into two streams by a flow divider II, one stream enters the coal and biomass co-gasification unit to undergo a gasification reaction with the mixed feed, and the other stream enters the carbon dioxide hydrogenation to methanol unit to produce methanol products; the high-purity hydrogen I produced by the water-gas shift adsorption enhanced hydrogen production unit is mixed with the syngas III by a mixer and then enters the syngas to methanol unit.

[0010] Further, the synthesis gas to methanol unit comprises a methanol synthesis reactor I, a high pressure separator I, a pre-fractionation column and a main methanol fractionation column; 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 out unreacted gas, a part of which is recycled as recycle reaction gas I back to the methanol synthesis reactor I, a part of which is discharged as purge gas I, the separated high pressure separator liquid I enters the pre-fractionation column to separate out light component product, and then the crude methanol II in the column bottom enters the main methanol fractionation column to obtain methanol product I and waste water I.

[0011] Further, the synthesis gas to methanol unit comprises a methanol synthesis reactor I, a high pressure separator I, a pre-fractionation column and a main methanol fractionation column; 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 out unreacted gas, a part of which is recycled as recycle reaction gas I back to the methanol synthesis reactor I, a part of which is discharged as purge gas I, the separated high pressure separator liquid I enters the pre-fractionation column to separate out light component product, and then the crude methanol II in the column bottom enters the main methanol fractionation column to obtain methanol product I and waste water I.

[0012] A method for low-carbon co-conversion of coal and biomass to methanol, comprising the following steps:

[0013] a) : coal and biomass are sent into a mixing crusher to generate mixed feed by crushing and mixing;

[0014] b) : the mixed feed generated in step a) enters a gasification furnace, water vapor as a gasification agent is added to generate crude synthesis gas and ash, the crude synthesis gas enters a desulfurization tower, the desulfurized synthesis gas enters a convection heat exchanger to be cooled and then enters a gas-liquid separator to obtain synthesis gas I and unreacted water vapor, the synthesis gas I enters a flow divider to be divided into synthesis gas II and synthesis gas III;

[0015] c) : the unreacted water vapor generated in step b) and the synthesis gas II enter a water-gas shift adsorption enhanced reactor to generate hydrogen I and carbon dioxide, the reaction temperature is 200-350℃, the adsorbent enters the adsorption to generate adsorption saturated adsorbent and release carbon dioxide I;

[0016] d) : the synthesis gas III generated in step b) and the hydrogen I generated in step c) enter a mixer and then are sent into a methanol synthesis reactor I to generate crude methanol I, the reaction temperature is 200-300℃;

[0017] e) : the adsorption saturated adsorbent generated in step c) enters an adsorbent regeneration reactor to generate adsorbent and release carbon dioxide I, the adsorbent is recycled, and the reaction temperature is 350-450℃;

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

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

[0020] h) The crude methanol II obtained in step g) enters the main methanol rectification column, and methanol product I is obtained at the top, and waste water I is obtained at the bottom;

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

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

[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 is obtained;

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

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

[0026] Further, the gasifier in step b) is one of a fixed bed, a fluidized bed and an entrained flow bed.

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

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

[0029] The present application has the following beneficial effects:

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

[0031] 2) Biomass is co-gasified with coal in a certain proportion, which can make up for the shortage of coal resources, reduce the emission of gas pollutants during the use of coal, especially the emission of CO2, improve the efficiency of coal gasification reaction and promote the effective use of elements such as C, H and O in 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 steps of syngas preparation and gas separation, remove the CO2 generated by the water-gas shift reaction in-situ by adding an adsorbent, improve the conversion rate and selectivity, and produce high-purity H2 in one step and enrich and recover pure CO2.

[0033] 4) CO2 is chemically utilized to produce methanol, which can reduce the emission of CO2 on the one hand and increase the yield of methanol on the other hand. BRIEF DESCRIPTION OF DRAWINGS

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

[0035] In the figure: 1, coal; 2, biomass; 3, mixed feed; 4, steam; 5, ash; 6, crude syngas; 7, desulfurized syngas; 8, hydrogen sulfide; 9, syngas after cooling; 10, syngas I; 11, unreacted steam; 12, syngas II; 13, syngas III; 14, hydrogen I; 15, adsorbent; 16, saturated adsorbent; 17, carbon dioxide I; 18, mixed syngas; 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, waste water I; 27, carbon dioxide II; 28, carbon dioxide III; 29, hydrogen II; 30, crude methanol III; 31, 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, waste water II; B1, mixing crusher; B2, gasifier; B3, desulfurization tower; B4, convection heat exchanger; B5, gas-liquid separator; B6, splitter 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-fractionation column; B13, main methanol rectification column; B14, splitter II; B15, methanol synthesis reactor II; B16, high-pressure separator II; B17, low-pressure separator; B18, methanol rectification column. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below. 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 obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0037] It should be noted that the terms "first", "second" and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those clearly listed steps or units, but can include other steps or units 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 the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended 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, in addition to indicating the orientation or positional relationship, the above-mentioned part of the terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0040] In addition, the terms "mount", "set", "provided with", "connect", "connect", "socket" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] As Figure 1As shown, the present application provides a system for low-carbon co-conversion of coal and biomass to methanol, comprising: a coal and biomass co-gasification unit, a water-gas shift adsorption enhanced hydrogen production unit, a syngas 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 syngas I 10 generated by the coal and biomass co-gasification unit enters the water-gas shift adsorption enhanced hydrogen production unit and the syngas to methanol unit; the high-purity hydrogen produced by the water-gas shift adsorption enhanced hydrogen production unit enters the syngas 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 syngas 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.

[0043] 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 flow divider IB6; the gasification of the mixed feed 3 by the gasifier B2 produces a crude syngas 6; the crude syngas 6 is subjected to hydrogen sulfide removal by the desulfurization tower B3; the desulfurized syngas 7 is cooled by the convection heat exchanger B4; the unreacted steam 11 in the cooled syngas 9 is separated by the gas-liquid separator B5 to produce the syngas I 10; wherein the syngas I 10 is divided into two streams by the flow divider IB6, one stream enters the syngas to methanol unit as syngas III 13, and the other stream enters the water-gas shift adsorption enhanced hydrogen production unit as syngas II 12 together with the unreacted steam 11.

[0044] 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 syngas II 12 enters the water-gas shift adsorption enhanced reactor B7 to undergo a water-gas shift reaction with the unreacted steam 11 to produce hydrogen and carbon dioxide, the adsorbent 15 chemically reacts with the produced carbon dioxide to capture the produced carbon dioxide, causing the water-gas shift reaction to shift to the right, the adsorption saturated adsorbent 16 enters the adsorbent regeneration reactor B8 to undergo an adsorbent regeneration reaction, the regenerated adsorbent 15 is recycled into the water-gas shift adsorption enhanced reactor B7 to undergo an adsorption reaction, and the produced carbon dioxide I 17 is divided into two streams by the flow divider II B14, one stream enters the coal and biomass co-gasification unit to undergo a gasification reaction with the mixed feed 3 as carbon dioxide II 27, and the other stream enters the carbon dioxide hydrogenation to methanol unit to produce methanol products; the high-purity hydrogen I 14 produced by the water-gas shift adsorption enhanced hydrogen production unit is mixed with the syngas III 13 by a mixer B9 and then enters the syngas to methanol unit.

[0045] The synthesis gas to methanol unit includes a methanol synthesis reactor IB10, a high-pressure separator IB11, a pre-distillation column B12, and a methanol main distillation column B13; wherein the 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 out unreacted gas, a part of which is recycled as circulating reaction gas I 20 back to the methanol synthesis reactor IB10, a part of which is discharged as purge gas I 21, the separated high-pressure separator liquid I 22 enters the pre-distillation column B12 to separate out light component product 23, and then the crude methanol II 24 in the column bottom enters the methanol main distillation column B13 to obtain methanol product I 25 and waste water I 26.

[0046] The carbon dioxide hydrogenation to methanol unit includes a methanol synthesis reactor II B15, a high-pressure separator II B16, a low-pressure separator B17, and a methanol distillation column B18; wherein the carbon dioxide III 28 enters the methanol synthesis reactor II B15 to react 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 recycled 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 recycled as circulating reaction gas III 33 back to the methanol synthesis reactor II B15, a part of which is discharged as purge gas II 34, and the separated low-pressure separator liquid 35 enters the methanol distillation column B18 to obtain methanol product II 36 and waste water II 37.

[0047] The present application adopts coal and biomass co-gasification, fully utilizes 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 going through the traditional water-gas shift unit and acid gas removal unit in the coal-to-methanol process, and can capture carbon dioxide at one time, thereby reducing the energy consumption for carbon capture. In addition, the production of methanol from carbon dioxide can reduce carbon emissions and increase methanol production. The method significantly improves the resource and energy utilization rate and reduces carbon emissions.

[0048] The present application also provides a method for low-carbon co-conversion of coal and biomass to methanol, which comprises the following steps:

[0049] a): coal and biomass are sent into a mixing crusher B1 to generate mixed feed 3 by crushing and mixing, wherein the coal in the obtained mixed feed is 0-100wt%, and the biomass is 0-100wt%;

[0050] b): the mixed feed 3 produced in step a) enters a gasifier, water vapor 4 is added as gasification agent, a gasification reaction occurs to produce crude synthesis gas 6 and ash 5, the crude synthesis gas 6 enters a desulfurization tower to remove hydrogen sulfide 8, the desulfurized synthesis gas 7 enters a convection heat exchanger B4 to be cooled and then enters a gas-liquid separator B5 to separate water vapor, to obtain synthesis gas I 10 and unreacted water vapor 11, the synthesis gas I 10 enters a flow divider B6 to be divided into synthesis gas II 12 and synthesis gas III 13, wherein the gasifier is one of a fixed bed, a fluidized bed and an entrained flow bed, and the temperature of the gasifier is 700-1000℃;

[0051] c): the unreacted water vapor 11 produced in step b) and the synthesis gas II 12 enter a 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℃, and the adsorbent 15 enters to adsorb the produced carbon dioxide to generate adsorption saturated adsorbent 16, wherein the adsorbent is one of magnesium oxide and calcium oxide;

[0052] d): the synthesis gas III 13 produced in step b) and the hydrogen I 14 produced in step c) enter a mixer B9 and then are sent to a methanol synthesis reactor IB10 to produce crude methanol I 19, the reaction temperature is 200-300℃, and wherein the catalyst used in the methanol synthesis gas reactor IB10 is one or a mixture of several of CuO, Al2O3 and ZnO. Preferably, the weight ratio of the components of the mixed catalyst is: CuO 20-75 parts, ZnO 15-50 parts, and Al2O3 50 parts. The single-pass conversion rate of the mixed synthesis gas 18 is 0-100%.

[0053] e): the adsorption saturated adsorbent 16 produced in step c) enters an adsorbent regeneration reactor B8 to be heated to produce adsorbent 15 and release carbon dioxide I 17, the adsorbent 15 is recycled, and the reaction temperature is 350-450℃;

[0054] f): the crude methanol I 19 produced in step d) enters a high-pressure separator IB11, the obtained gas is circulated back to the methanol synthesis reactor IB10 as circulating reaction gas I 20, is discharged as purge gas I 21, and is the high-pressure separator liquid I 22;

[0055] g): the high-pressure separator liquid I 22 obtained in step f) enters a pre-fractionation tower B12, to obtain light component product 23 at the top and crude methanol II 24 at the bottom;

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

[0057] i) : The carbon dioxide I 17 generated in step e) enters the flow divider II B 14, 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 gasification agent to react with the mixed feed to produce a crude synthesis gas, and the carbon dioxide III 28 enters the carbon dioxide hydrogenation methanol unit;

[0058] j) : The carbon dioxide III 28 generated in step i) enters the methanol synthesis reactor II B 15 together with hydrogen II 29, to obtain a crude methanol III 30, wherein the reaction temperature is 200-300 DEG C;

[0059] k) : The crude methanol III 30 generated in step j) enters the high-pressure separator II B 16, to obtain a circulating reaction gas II 32 which is recycled to the methanol synthesis reactor II B 15, and a high-pressure separator liquid II 31;

[0060] l) : The high-pressure separator liquid II 31 obtained in step k) enters the low-pressure separator B 17, to obtain a circulating reaction gas III 33 which is recycled to the methanol synthesis reactor II B 15, a purge gas II 34 which is discharged, and a low-pressure separator liquid 35;

[0061] m) : The low-pressure separator liquid 35 obtained in step l) enters the methanol rectification column B 18, to obtain a methanol product II 36 at the top and a waste water II 37 at the bottom, wherein the mass fraction of methanol in the methanol product II 36 is greater than 99.9%.

[0062] The present application uses solar energy as a system heat source, which not only saves the air separation unit to reduce energy consumption, but also avoids the waste of elements caused by direct coal combustion and reduces the pollution of combustion by-products CO2 to synthesis gas. The biomass is co-gasified with coal in a certain proportion, which can make up for the shortage of coal resources, reduce the emission of gas pollutants during the use of coal, especially the emission of CO2, improve the efficiency of coal gasification reaction, and promote the effective use 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, remove the CO2 generated by the water-gas shift reaction in-situ by adding an adsorbent, and improve the conversion rate and selectivity. High-purity H2 is produced in one step, and pure CO2 is enriched and recovered. The chemical utilization of CO2 to produce methanol can reduce CO2 emissions on the one hand and increase methanol production on the other hand.

[0063] Example 1:

[0064] As shown in the figure, 6t / h of coal 1 and 4t / h of biomass are sent into the mixing crusher B1 and then into the gasifier B2, the temperature of the gasifier is 900 DEG C, the steam 4 as a gasification agent is 7t / h, and 105,000 m3 / h of synthesis gas is produced. Figure 1 ​3 / h of crude synthesis gas 6, the crude synthesis gas 6 is desulfurized by the desulfurization tower B3 to remove hydrogen sulfide 8, and then enters the counter-flow heat exchanger B4 to 101,800m 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 separation of unreacted water vapor 11 in the synthesis gas 9 produces 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. 3 / h of synthesis gas II12 enters the water-gas shift adsorption enhanced reactor B7 and reacts 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. 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 undergo gasification reaction with mixed feed 3, and the remaining 6.3t / h enters the carbon dioxide hydrogenation to methanol unit to produce 4.3t / h of methanol product. The 17,100m3 generated by the water-gas shift adsorption enhanced hydrogen production unit 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] Example 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 gasifying agent water vapor 4 is 7t / h, generating 103,100m 3 / h of crude synthesis gas 6, the crude synthesis gas 6 is desulfurized by the desulfurization tower B3 to remove hydrogen sulfide 8, and then enters the counter-flow heat exchanger B4 to 100,600m 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 separation of unreacted water vapor 11 in the synthesis gas 9 produces 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. 3 / h of synthesis gas II12 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. 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 17,800m3 generated by the water-gas shift adsorption enhanced hydrogen production unit 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 merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor 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 generated by the water-gas shift adsorption enhanced hydrogen production unit enters the synthesis gas to methanol unit, and the 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 to synthesize methanol product I (25); the carbon dioxide hydrogenation to methanol unit is used to synthesize methanol product II (36); 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 enters the water gas shift adsorption enhanced hydrogen production unit with the unreacted water vapor (11); 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 reacts 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 equilibrium of the water-gas shift reaction to shift to the right, and the adsorbent (16) that is saturated with adsorption enters the adsorbent regeneration reactor (B8) to undergo adsorbent regeneration reaction, and the regenerated adsorbent The additive (15) is circulated into the water-gas shift adsorption enhanced reactor (B7) to undergo 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) and 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) and 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; 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, the mixed synthesis gas (18) enters the methanol synthesis reactor I (B10) to generate crude methanol I (19), the product enters the high-pressure separator I (B11) to separate the unreacted gas, a part of which is recycled 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 the light component product (23), and then the crude methanol II (24) in the tower bottom enters the methanol main distillation tower (B13) to obtain the methanol product I (25) and wastewater I (26); 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 portion of which is circulated back to the methanol synthesis reactor II (B15) as circulating reaction gas III (33) and a portion 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).

2. 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 I (B6) and is divided into synthesis gas II (12) and synthesis gas III (13); c): The unreacted water vapor (11) produced in step b) and the synthesis gas II (12) 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 adsorption 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 fed into the methanol synthesis reactor I (B10) to produce crude methanol I (19). 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). The adsorbent (15) is recycled. 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 one of the gases obtained is the circulating reaction gas I (20) which is circulated back to the methanol synthesis reactor I (B10), and the other is the purge gas I (21) which is discharged, as well as the high-pressure separator liquid I (22); g): The high-pressure separator liquid I (22) 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 II (24) is obtained at the bottom of the tower; h): The crude methanol II (24) obtained in step g) enters the methanol main distillation tower (B13), and the methanol product I (25) is obtained at the top of the tower, and the wastewater 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 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), with the reaction temperature being 200-300°C; k): The crude methanol III (30) produced in step j) enters the high-pressure separator II (B16), and the resulting circulating reaction gas II (32) is circulated back to the methanol synthesis reactor II (B15) and the resulting 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 the methanol distillation tower (B18), and methanol product II (36) is obtained at the top of the tower, and wastewater II (37) is obtained at the bottom of the tower.

3. The method for producing methanol by low-carbon co-conversion of coal and biomass according to claim 2, characterized in that: The gasification furnace in step b) is a fixed bed, fluidized bed or entrained flow bed.

4. The method for producing methanol by low-carbon co-conversion of coal and biomass according to claim 2, characterized in that: In the step c), the adsorbent is one of magnesium oxide and calcium oxide.

5. The method for producing methanol by low-carbon co-conversion of coal and biomass according to claim 2, 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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