A green methanol production system and method

Abstract

The present invention discloses a green methanol production system and method, wherein the green methanol production system includes a hydrogen production unit, a methanol synthesis unit and a catalyst regeneration unit, wherein the hydrogen production unit is used to obtain hydrogen and oxygen; the methanol synthesis unit has a first hydrogen inlet, a carbon dioxide inlet, a catalyst inlet and a catalyst outlet, wherein the first hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit; the catalyst regeneration unit has a second hydrogen inlet, a regenerated catalyst inlet, a regenerated catalyst outlet and a second hydrogen outlet, wherein the second hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit, the regenerated catalyst inlet is connected to the catalyst outlet, and the regenerated catalyst outlet is connected to the catalyst inlet. The green methanol production system of the present invention can reduce energy consumption in the green methanol production process, improve the economy of green methanol, and solve the matching problem between methanol production and fluctuating renewable energy.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular to a green methanol production system and method. Background Art

[0002] Hydrogen energy is considered to be a secondary energy source that can be used in parallel with electricity in the future. However, the storage and transportation of hydrogen energy still faces the problems of high energy consumption, high cost and high risk.

[0003] In view of the problem of hydrogen energy storage and transportation, converting hydrogen into methanol and then transporting and utilizing it is a promising solution. Methanol is a mature industrial product that can be directly used in fuel cells and can also be used as a precursor for the conversion of other organic products. It can be used as a hydrogen storage carrier to indirectly realize the spatial and temporal configuration of hydrogen energy, thereby meeting the flexibility requirements of new energy systems. In addition, the production of methanol using carbon dioxide and hydrogen as raw materials can also achieve carbon capture and utilization, which is a technical means with carbon emission reduction benefits.

[0004] However, the production of green methanol using green hydrogen as raw material is still in its early stages. Limited by the economic feasibility of using green hydrogen to produce methanol, the high temperature and high pressure conditions of the methanol synthesis process also limit the flexible production of methanol and its matching with fluctuating renewable energy. Summary of the invention

[0005] In view of this, one object of the present invention is to propose a green methanol production system, which can reduce the energy consumption in the green methanol production process, improve the economy of green methanol, and solve the matching problem between methanol production and fluctuating renewable energy.

[0006] The second object of the present invention is to provide a green methanol production method.

[0007] To achieve the above object, the first embodiment of the present invention provides a green methanol production system, comprising:

[0008] A hydrogen production unit, wherein the hydrogen production unit is used to obtain hydrogen and oxygen;

[0009] A methanol synthesis unit, wherein the methanol synthesis unit has a first hydrogen inlet, a carbon dioxide inlet, a catalyst inlet and a catalyst outlet, and the first hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit;

[0010] A catalyst regeneration unit, wherein the catalyst regeneration unit has a second hydrogen inlet, a regenerated catalyst inlet, a regenerated catalyst outlet and a second hydrogen outlet, wherein the second hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit, the regenerated catalyst inlet is connected to the catalyst outlet, the regenerated catalyst outlet is connected to the catalyst inlet, and the second hydrogen outlet is connected to the first hydrogen inlet.

[0011] In some embodiments of the present invention, the green methanol production system further includes a boiler; the fuel inlet of the boiler is connected to the oxygen outlet of the hydrogen production unit, and the steam outlet of the boiler is connected to the first steam inlet of the methanol synthesis unit and the second steam inlet of the catalyst regeneration unit.

[0012] In some embodiments of the present invention, the hydrogen production unit adopts a water electrolysis hydrogen production system or a water photolysis hydrogen production system.

[0013] In some embodiments of the present invention, the water electrolysis hydrogen production system is electrically connected to a renewable energy power generation system.

[0014] In some embodiments of the present invention, the water electrolysis hydrogen production system is one or more of an alkaline water electrolysis hydrogen production system, a proton exchange membrane water electrolysis hydrogen production system, an alkaline ion membrane water electrolysis hydrogen production system, or a high-temperature solid oxide water electrolysis hydrogen production system.

[0015] In some embodiments of the present invention, the catalyst is a carbon dioxide hydrogenation to methanol catalyst.

[0016] In some embodiments of the present invention, the catalyst is a metal dispersed on the surface of a carbon-based or metal oxide-based support.

[0017] In some embodiments of the present invention, the catalyst is one of Cu / ZnO / Al2O3, Cu / CeO2, and Cu / ZnO / SiO2.

[0018] In some embodiments of the present invention, the methanol synthesis unit and the catalyst regeneration unit are both gas-solid reaction equipment; the gas-solid reaction equipment includes a reactor; the reactor is a fixed bed reactor, a fluidized bed reactor or an intermittent fully mixed kettle reactor.

[0019] In some embodiments of the present invention, the reactor in the methanol synthesis unit has the first hydrogen inlet, the carbon dioxide inlet, the catalyst inlet and the catalyst outlet; the reactor in the catalyst regeneration unit has the second hydrogen inlet, the regenerated catalyst inlet, the regenerated catalyst outlet and the second hydrogen outlet.

[0020] In some embodiments of the present invention, the catalyst outlet is located at the upper end of the reactor in the methanol synthesis unit, and the regenerated catalyst inlet is located at the lower end of the reactor in the catalyst regeneration unit.

[0021] To achieve the above-mentioned object, the second embodiment of the present invention proposes a green methanol production method, which is applied to the green methanol production system of the embodiment of the present invention, comprising:

[0022] A portion of the hydrogen produced by the hydrogen production unit is used as feed gas to enter the methanol synthesis unit to react with carbon dioxide under the action of a catalyst to generate methanol, and the other portion enters the catalyst regeneration unit to participate in the regeneration of the deactivated catalyst from the methanol synthesis unit;

[0023] The hydrogen flowing out of the catalyst regeneration unit and the obtained regenerated catalyst re-enter the methanol synthesis unit to participate in the methanol synthesis reaction.

[0024] In some embodiments of the present invention, the green methanol production method further includes: oxygen produced by the hydrogen production unit enters the boiler to assist combustion and produce steam, and the steam is used as a heat exchange medium to assist in generating the temperature required for methanol synthesis and catalyst regeneration.

[0025] In some embodiments of the present invention, the reaction temperatures of the methanol synthesis unit and the catalyst regeneration unit are both 200-400°C.

[0026] In some embodiments of the present invention, the reaction pressure of the methanol synthesis unit is 1-7 MPa, and the reaction pressure of the catalyst regeneration unit is 0.1-10 MPa.

[0027] In some embodiments of the present invention, the catalyst loading of the methanol synthesis unit is calculated as follows:

[0028] m1=SQ 1，H2 / nR com

[0029] Where:

[0030] m1——catalyst loading of methanol synthesis unit, kg;

[0031] Q 1，H2 ——Hydrogen production of the hydrogen production unit, mol / h;

[0032] S——target methanol synthesis conversion rate, %;

[0033] n——the flow ratio of all hydrogen and carbon dioxide entering the methanol synthesis unit;

[0034] R com ——Reaction rate of methanol synthesis unit, mol / kg / h.

[0035] In some embodiments of the present invention, the target methanol synthesis conversion rate is calculated as follows:

[0036] S=[N(in)-N(out)] / N(in)

[0037] Where:

[0038] N(in)——the molar flow rate of carbon dioxide entering the methanol synthesis unit, mol / h;

[0039] N(out)——the molar flow rate of carbon dioxide out of the methanol synthesis unit, mol / h;

[0040] In some embodiments of the present invention, the reaction rate of the methanol synthesis unit is the number of moles of methanol produced per kilogram of catalyst particle surface per unit time.

[0041] In some embodiments of the present invention, the flow ratio of hydrogen to carbon dioxide entering the methanol synthesis unit is 3-10, preferably 3-4;

[0042] In some embodiments of the present invention, the target methanol synthesis conversion rate is 10-30%.

[0043] In some embodiments of the present invention, the catalyst loading of the catalyst regeneration unit is calculated as follows:

[0044] m2=m1*Q 1,H2 / Q 3,H2 *R d / R g

[0045] Where:

[0046] m2——catalyst loading in catalyst regeneration unit, kg;

[0047] m1——catalyst loading of methanol synthesis unit, kg;

[0048] Q 1,H2 ——Hydrogen production of the hydrogen production unit, mol / h

[0049] Q 3,H2 ——Hydrogen flow rate entering the catalyst regeneration unit, mol / h;

[0050] R d ——catalyst deactivation rate, h -1 ;

[0051] R g ——Catalyst regeneration rate, h -1 .

[0052] In some embodiments of the present invention, the ratio of the hydrogen production of the hydrogen production unit to the hydrogen flow rate entering the catalyst regeneration unit is between 2-10.

[0053] In some embodiments of the present invention, the rated hydrogen production of the hydrogen production unit is equal to the hydrogen consumption of the methanol synthesis unit under design conditions.

[0054] In some embodiments of the present invention, the judgment criterion for determining whether the catalyst in the methanol synthesis unit has reached a replacement state is that the catalyst activity reaches a preset catalyst replacement value, and the preset catalyst replacement value is 90-95%; the conversion rate of methanol synthesis is the product of the preset catalyst replacement value and the target methanol synthesis conversion rate.

[0055] In some embodiments of the present invention, the criterion for determining whether the catalyst regeneration unit has completed catalyst regeneration is that the catalyst activity in the catalyst regeneration unit reaches a catalyst regeneration value, and the regeneration value is 95-100%;

[0056] The time for the catalyst regeneration unit to complete catalyst regeneration is calculated as follows:

[0057] t=(a2-a1) / R g

[0058] Where:

[0059] t——the time when the catalyst regeneration unit completes the catalyst regeneration, d;

[0060] a1——preset catalyst replacement value, 90-95%;

[0061] a2——catalyst regeneration value, 95-100%, and a2>a1;

[0062] R g ——Catalyst regeneration rate, h -1 .

[0063] The green methanol production system of the embodiment of the present invention can bring the following beneficial effects:

[0064] (1) The hydrogen production unit, methanol synthesis unit and catalyst regeneration unit are coupled. The system input is carbon dioxide and the output is methanol, which avoids the difficulties in hydrogen storage and transportation. While utilizing green hydrogen, it can also reduce carbon dioxide emissions, and at the same time achieve catalyst regeneration and reuse, which can ensure the sustainable production of methanol.

[0065] (2) The by-product oxygen produced by the hydrogen production unit is introduced into the boiler for use as auxiliary combustion to produce the heat exchange medium (high-temperature steam) required to ensure the reaction temperature of the methanol synthesis unit and the catalyst regeneration unit, which has high material utilization and saves energy.

[0066] (3) The catalyst is regenerated through the hydrogen generated in the system with the auxiliary combustion of by-product oxygen, which saves overall energy consumption, extends the system working time, and improves the economic efficiency of green hydrogen to methanol.

[0067] (4) When the hydrogen production unit adopts a photocatalytic water hydrogen production system or an electrolytic water hydrogen production system electrically connected to a renewable energy power generation system, the reaction hydrogen flow rate can be matched with the renewable energy hydrogen production power, and the reaction space velocity of the methanol synthesis unit and the catalyst regeneration unit can be adjusted accordingly to maintain the designed reaction conversion rate, thereby improving the adaptability to renewable energy;

[0068] (5) The catalyst loading of the methanol synthesis unit and the catalyst regeneration unit can be determined according to the capacity of the hydrogen production unit, providing sufficient operating space for flexible adjustment.

[0069] (6) The operating parameters can be flexibly adjusted to obtain different products such as methanol, methanol + hydrogen, methanol + oxygen, etc.

[0070] (7) The hydrogen production unit adopts a photolysis water hydrogen production system or an electrolysis water hydrogen production system electrically connected to a renewable energy power generation system, which can save energy.

[0071] The beneficial effects of the green methanol production method of the embodiment of the present invention are basically the same as the beneficial effects of the green methanol production system of the embodiment of the present invention, and will not be repeated here.

[0072] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0074] Figure 1 It is a simple structural schematic diagram of a green methanol production system according to an embodiment of the present invention (also a simple flow chart of a green methanol production method).

[0075] Figure 2 It is a simple structural schematic diagram of a green methanol production system according to another embodiment of the present invention.

[0076] Reference numerals:

[0077] 1-Hydrogen production unit; 2-Methanol synthesis unit; 3-Catalyst regeneration unit; 4-Boiler. DETAILED DESCRIPTION

[0078] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0079] The green methanol production system and green methanol production method according to the embodiments of the present invention are described below with reference to the accompanying drawings.

[0080] Figure 1 Schematic diagram of a simple structure of a green methanol production system according to an embodiment of the present invention.

[0081] like Figure 1 As shown, the green methanol production system of an embodiment of the present invention includes a hydrogen production unit 1, a methanol synthesis unit 2 and a catalyst regeneration unit 3, the hydrogen production unit 1 is used to obtain hydrogen and oxygen; the methanol synthesis unit 2 has a first hydrogen inlet, a carbon dioxide inlet, a catalyst inlet and a catalyst outlet, the first hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit 1; the catalyst regeneration unit 3 has a second hydrogen inlet, a regenerated catalyst inlet, a regenerated catalyst outlet and a second hydrogen outlet, the second hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit 1, the regenerated catalyst inlet is connected to the catalyst outlet, the regenerated catalyst outlet is connected to the catalyst inlet, and the second hydrogen outlet is connected to the first hydrogen inlet.

[0082] The green methanol production system of the embodiment of the present invention couples a hydrogen production unit, a methanol synthesis unit and a catalyst regeneration unit. The system input is carbon dioxide and the output is methanol, thereby avoiding difficulties in hydrogen storage and transportation. While utilizing green hydrogen, it can achieve carbon dioxide emission reduction, and at the same time achieve catalyst regeneration and reuse, thereby ensuring the sustainable production of methanol. The catalyst loading of the methanol synthesis unit and the catalyst regeneration unit can be determined according to the capacity of the hydrogen production unit, providing sufficient operating space for flexible adjustment. The operating parameters can be flexibly adjusted to obtain different products such as methanol, methanol + hydrogen, and methanol + oxygen.

[0083] In some embodiments, in order to use the byproducts produced by the hydrogen production unit in the green methanol system of the present invention, Figure 2 As shown, the green methanol production system also includes a boiler 4; the fuel inlet of the boiler 4 is connected to the oxygen outlet of the hydrogen production unit, and the steam outlet of the boiler is connected to the first steam inlet of the methanol synthesis unit and the second steam inlet of the catalyst regeneration unit, so that the by-products produced by the hydrogen production unit can be used as auxiliary fuel to enter the boiler for combustion, heat cold water, sewage, oil and other fluids to generate high-temperature steam, and then use the high-temperature steam as a high-temperature heat exchange medium to supplement heat for the methanol synthesis unit and the catalyst regeneration unit, and assist in providing the reaction temperature required by each of them, with high material utilization and energy saving; at the same time, the catalyst is regenerated under the auxiliary combustion of the by-product oxygen through the hydrogen generated in the system, saving overall energy consumption, extending the system working time, and improving the economy of green hydrogen to methanol.

[0084] It should be noted that the boiler can be installed in the boiler room of the factory, and the type of boiler can be a waste heat boiler, a gas boiler, etc.

[0085] In some embodiments, the hydrogen production unit 1 can adopt an electrolytic water hydrogen production system, such as an alkaline electrolytic water hydrogen production system, a proton exchange membrane electrolytic water hydrogen production system, an alkaline ion membrane electrolytic water hydrogen production system, or a high-temperature solid oxide electrolytic water hydrogen production system. When the hydrogen production unit 1 can adopt an electrolytic water hydrogen production system, such as an alkaline electrolytic water hydrogen production system, a proton exchange membrane electrolytic water hydrogen production system, an alkaline ion membrane electrolytic water hydrogen production system, or a high-temperature solid oxide electrolytic water hydrogen production system, each hydrogen production system is arranged in parallel to produce hydrogen respectively, and then collected uniformly. Electrolytic water hydrogen production is to pass direct current into an electrolytic cell filled with electrolyte, and water molecules undergo electrochemical reactions on the electrodes to decompose into hydrogen and oxygen. The alkaline electrolytic water hydrogen production system, proton exchange membrane electrolytic water hydrogen production system, alkaline ion membrane electrolytic water hydrogen production system, and high-temperature solid oxide electrolytic water hydrogen production system involved in the present invention are all existing electrolytic water hydrogen production systems, and the specific structure and working principle are not repeated.

[0086] In the present invention, when the electrolysis hydrogen production unit adopts the water electrolysis hydrogen production system, the electric energy of the water electrolysis hydrogen production system can be the electric energy of the power grid, or the electric energy generated by the renewable energy power generation system. However, since the use of the electric energy of the power grid for water electrolysis hydrogen production has high energy consumption and large greenhouse gas emissions, and renewable energy has the characteristics of cleanliness and environmental protection, the water electrolysis hydrogen production system can be electrically connected to the existing wind energy, solar energy and other renewable energy power generation systems, and the electric energy generated by the renewable energy power generation system is used to electrolyze water to produce hydrogen, which has low energy consumption, less greenhouse gas release during the entire preparation process, and the obtained hydrogen has high purity and less impurity content.

[0087] In other embodiments, the hydrogen production unit 1 may adopt an existing photocatalytic water splitting hydrogen production system. The principle of photocatalytic water splitting hydrogen production is to directly utilize solar energy to decompose water to produce hydrogen and oxygen with the assistance of a photocatalyst.

[0088] In some embodiments, the catalyst in the methanol synthesis unit and the catalyst in the catalyst regeneration unit are both carbon dioxide hydrogenation methanol catalysts, such as metals dispersed on the surface of a carbon-based or metal oxide-based carrier, wherein the carrier includes but is not limited to one or more of ZnO, Al2O3, ZrO2, CeO2, SiO2, In2O3, porous activated carbon, etc., and the metal dispersed on the surface of the carrier includes but is not limited to one or more of Cu, Pd, Pt, Ni, La, Co, etc. As a possible example, the catalyst in the methanol synthesis unit and the catalyst in the catalyst regeneration unit can be one of Cu / ZnO / Al2O3, Cu / CeO2, and Cu / ZnO / SiO2, which are commercially available or homemade by known methods.

[0089] In some embodiments, the methanol synthesis unit 2 and the catalyst regeneration unit 3 are both commonly used gas-solid reaction equipment in industry, mainly including a reactor and matching pipeline accessories, wherein the reactor can be a fixed bed reactor, a fluidized bed reactor or an intermittent fully mixed kettle reactor. The first hydrogen inlet, the first steam inlet, the carbon dioxide inlet, the catalyst inlet and the catalyst outlet of the methanol synthesis unit 2 are all arranged on the reactor in the methanol synthesis unit, wherein the first steam inlet is connected to the heat exchange coil of the reactor in the methanol synthesis unit; the second hydrogen inlet, the second steam inlet, the regenerated catalyst inlet, the regenerated catalyst outlet and the second hydrogen outlet of the catalyst regeneration unit 3 are all arranged on the reactor in the catalyst regeneration unit, wherein the second steam inlet is connected to the heat exchange coil of the reactor in the catalyst regeneration unit.

[0090] In some embodiments, the catalyst outlet is located at the upper end of the reactor in the methanol synthesis unit 2, and the regenerated catalyst inlet is located at the lower end of the reactor in the catalyst regeneration unit 3. When the catalyst particles reach the replacement state, the input of the reaction gases hydrogen and carbon dioxide is stopped, and the catalyst particles are blown out to the catalyst inlet at the lower part of the catalyst regeneration unit 3. The catalyst to be regenerated contacts hydrogen in the reactor of the catalyst regeneration unit 3, and a reduction regeneration reaction occurs.

[0091] As a possible example, the reactors in the methanol synthesis unit 2 and the catalyst regeneration unit 3 are both fluidized bed reactors.

[0092] The working process of the green methanol production system of the embodiment of the present invention is as follows:

[0093] A portion of the hydrogen produced by the hydrogen production unit 1 enters the methanol synthesis unit 2 as a raw gas to react with carbon dioxide to generate methanol; a portion enters the catalyst regeneration unit 3 to react with the deactivated catalyst to regenerate the catalyst. The oxygen produced by the hydrogen production unit 1 enters the boiler and burns as an auxiliary fuel to generate high-temperature steam (such as water vapor). The high-temperature steam and the like enter the methanol synthesis unit 2 and the catalyst regeneration unit 3 respectively as a high-temperature heat exchange medium to assist in generating the high temperature required for methanol synthesis and catalyst regeneration.

[0094] In the methanol synthesis unit 2, carbon dioxide and hydrogen enter the reactor and react with the catalyst particles in the reaction area to produce methanol. When the catalyst particles are deactivated and reach the replacement state, the input of the reaction gas carbon dioxide and hydrogen is stopped, and the deactivated catalyst particles are transferred to the catalyst regeneration unit 3.

[0095] In the catalyst regeneration unit 3, the hydrogen produced from the hydrogen production unit 1 contacts the deactivated catalyst particles from the methanol synthesis unit 2, and a reduction regeneration reaction occurs to regenerate the catalyst. The regenerated catalyst reenters the methanol synthesis unit 2, and the hydrogen from the second hydrogen outlet returns to the first hydrogen inlet of the methanol synthesis unit 2 to participate in the methanol synthesis reaction.

[0096] The green methanol production system of the embodiment of the present invention is applicable to the green methanol production method of the embodiment of the present invention. Figure 1 As shown, the green methanol production method of the embodiment of the present invention comprises the following steps:

[0097] A portion of the hydrogen produced by the hydrogen production unit 1 is used as a raw gas to enter the methanol synthesis unit 2 to react with carbon dioxide under the action of a catalyst to generate methanol, and the other portion enters the catalyst regeneration unit 3 to participate in the regeneration of the deactivated catalyst from the methanol synthesis unit 2;

[0098] The hydrogen flowing out of the catalyst regeneration unit 3 and the obtained regenerated catalyst re-enter the methanol synthesis unit 2 to participate in the methanol synthesis reaction.

[0099] In some embodiments, the green methanol production method of the present invention further includes: the oxygen produced by the hydrogen production unit 1 enters the boiler to assist combustion and produce steam, and the steam is used as a heat exchange medium to assist in generating the temperature required for methanol synthesis and catalyst regeneration.

[0100] In the production process of the green methanol production system, continuous and efficient synthesis of methanol is achieved by controlling the gas flow and gas-solid ratio between the hydrogen production unit 1, the methanol synthesis unit 2 and the catalyst regeneration unit 3. The specific process is as follows:

[0101] 1) For a specific type of catalyst, determine the reaction temperature of the methanol synthesis unit 2, the flow ratio of raw hydrogen and carbon dioxide, and the target methanol synthesis conversion rate; the reaction temperature of the catalyst regeneration unit 3; and the reaction rate Rcom (mol / kg / h) of the methanol synthesis unit 2;

[0102] 2) determining the catalyst deactivation rate in the methanol synthesis unit 2 and the catalyst regeneration rate in the catalyst regeneration unit 3, and obtaining a ratio of the two;

[0103] 3) Determine the catalyst loading of the methanol synthesis unit 2 according to the hydrogen production of the hydrogen production unit 1;

[0104] 4) The catalyst loading and hydrogen flow rate of the catalyst regeneration unit 3 are determined according to the ratio of the catalyst regeneration rate of the catalyst regeneration unit 3 to the catalyst deactivation rate in the methanol synthesis unit 2 and the reactor characteristics of the catalyst regeneration unit 3.

[0105] Among them, the process conditions for hydrogen production by water electrolysis vary depending on the specific selection of the hydrogen production unit:

[0106] When the hydrogen production unit selects the alkaline water electrolysis hydrogen production system, the process conditions are: temperature 70-90℃, working pressure 1.6MPa, chamber voltage 1.6-2.0V, current density 2000-4000A / m 2 As a possible example, when the hydrogen production unit selects the alkaline water electrolysis hydrogen production system, the process conditions are: temperature 80°C, working pressure 1.6MPa, chamber voltage 1.8V, current density 3000A / m 2 .

[0107] When the hydrogen production unit selects the proton exchange membrane water electrolysis hydrogen production system, the process conditions are: temperature 50-80℃, working pressure 1-7MPa, chamber voltage 1.6-2.0V, current density 5000-10000A / m 2 As a possible example, when the hydrogen production unit selects the proton exchange membrane water electrolysis hydrogen production system, the process conditions are: temperature 75°C, working pressure 4MPa, chamber voltage 1.8V, current density 8000A / m 2 .

[0108] When the hydrogen production unit selects the high-temperature solid oxide water electrolysis hydrogen production system, the process conditions are: temperature 700-850℃, working pressure 1.0MPa, chamber voltage 1.2-1.8V, current density 3000-6000A / m 2 As a possible example, when the hydrogen production unit selects a high-temperature solid oxide water electrolysis hydrogen production system, the process conditions are: temperature 800°C, working pressure 1.0MPa, chamber voltage 1.5V, current density 4500A / m 2 .

[0109] When the hydrogen production unit selects the alkaline ion exchange membrane water electrolysis hydrogen production system, the process conditions are: temperature 40-60℃, working pressure 1-3MPa, chamber voltage 1.6-2.0V, current density 2000-10000A / m 2 As a possible example, when the hydrogen production unit selects the alkaline ion exchange membrane water electrolysis hydrogen production system, the process conditions are: temperature 50°C, working pressure 2MPa, chamber voltage 1.8V, current density 6000A / m 2 .

[0110] Among them, the hydrogen flow ratio from the hydrogen production unit to the methanol synthesis unit and the hydrogen flow ratio entering the catalyst regeneration unit is (3-6):1, preferably 4:1; the water vapor flow ratio entering the methanol synthesis unit and the water vapor flow ratio entering the catalyst regeneration unit can be any ratio as long as the temperature of the auxiliary methanol production process and the temperature of the catalyst regeneration are met.

[0111] Among them, the reaction temperature of methanol synthesis unit 2 is 200-400°C, at which time the catalyst has a high reaction rate and reaction conversion rate (methanol synthesis reaction is an exothermic reaction, and too high a temperature is not conducive to the formation of reaction products, but too low a temperature will cause a high or low reaction rate, so it is necessary to select a suitable temperature range), preferably 240-350°C, more preferably 240-260°C; as a possible example, the reaction temperature of the methanol synthesis unit includes but is not limited to 230°C, 250°C, 260°C, 290°C, 300°C, 330°C, 360°C or 390°C. The reaction temperature of the catalyst regeneration unit 3 is 300-700°C, which is conducive to the occurrence of hydrogen reduction reaction. The reaction temperature of the methanol synthesis unit 2 is also the reaction temperature of hydrogen and carbon dioxide synthesizing methanol under the action of the catalyst, and the reaction temperature of the catalyst regeneration unit 3 is also the temperature at which the deactivated catalyst undergoes a reduction and regeneration reaction with hydrogen. The reaction temperature of the catalyst regeneration unit 3 includes but is not limited to 350°C, 400°C, 450°C, 500°C, 600°C or 650°C.

[0112] The reaction pressure of the methanol synthesis unit is 1-7MPa, preferably 3-5MPa; as a possible example, the reaction pressure of the methanol synthesis unit includes but is not limited to 2MPa, 3MPa, 4MPa, 5MPa or 6MPa. The reaction pressure of the catalyst regeneration unit is 0.1-10MPa, preferably 0.5-5MPa, more preferably 1-3MPa; as a possible example, the reaction pressure of the catalyst regeneration unit includes but is not limited to 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa or 9MPa.

[0113] The reaction space velocity of methanol synthesis from hydrogen and carbon dioxide under the action of catalyst in the methanol synthesis unit is 5000h -1 -20000h -1 , preferably 8000-16000h -1 , more preferably 10000-14000h -1 As a possible example, the reaction space velocity of the methanol synthesis unit includes, but is not limited to, for example, 8000h -1 、10000h -1 、12000h -1 、15000h -1 or 18000h -1 The reaction space velocity of the catalyst regeneration unit is 5000-40000h -1 , preferably 10000-30000h -1 As a possible example, the reaction space velocity of the catalyst regeneration unit includes but is not limited to 6000h -1 、10000h -1、15000h -1 、20000h -1 、25000h -1 、30000h -1 or 35000h -1 .

[0114] The catalyst loading of methanol synthesis unit 2 is calculated according to formula (1):

[0115] m1=SQ 1，H2 / nR com Formula (1)

[0116] In formula (1):

[0117] m1——catalyst loading of methanol synthesis unit, kg;

[0118] Q 1，H2 ——Hydrogen production of the hydrogen production unit, mol / h;

[0119] S——target methanol synthesis conversion rate, %;

[0120] n——the flow ratio of all hydrogen and carbon dioxide entering the methanol synthesis unit;

[0121] R com ——Reaction rate of methanol synthesis unit, mol / kg / h.

[0122] In formula (1), the target methanol synthesis conversion rate is calculated according to formula (2):

[0123] S=[N(in)-N(out)] / N(in) Formula (2)

[0124] In formula (2):

[0125] N(in)——the molar flow rate of carbon dioxide entering the methanol synthesis unit, mol / h;

[0126] N(out)——the molar flow rate of carbon dioxide out of the methanol synthesis unit, mol / h;

[0127] In formula (1), the reaction rate of the methanol synthesis unit is the number of moles of methanol produced per kilogram of catalyst particle surface per unit time. The reaction rate of the methanol synthesis unit under the conditions of a specific methanol synthesis reaction temperature, a flow ratio n of hydrogen entering the methanol synthesis unit to carbon dioxide, and a target methanol synthesis conversion rate S can be determined by experiments or data provided by the manufacturer when a specific type of catalyst is selected; the flow ratio of all hydrogen entering the methanol synthesis unit (consisting of hydrogen from the hydrogen production unit and hydrogen from the catalyst regeneration unit) to carbon dioxide is not less than 3, preferably 3-10, more preferably 3-4, such as 3.5, to ensure that the carbon dioxide in the reaction is completely converted as much as possible to reduce process carbon emissions. The target methanol synthesis conversion rate is not less than 10%, such as but not limited to 10-30%, such as 15%, 20% or 25%. If the target methanol synthesis conversion rate is too high, the reactant concentration in the methanol synthesis unit will be low, the product concentration will be high, and the reaction rate will be reduced, so that the reaction residence time will be extended, and a larger reaction device will be required to process the same amount of feed gas, which will increase investment; if the target methanol synthesis conversion rate is too low, the unit output of the methanol product will be reduced, and the production efficiency will be reduced.

[0128] In formula (1), the hydrogen production of the hydrogen production unit is matched with the power generation of renewable energy to obtain a certain renewable energy power generation and consumption effect. For example, the rated power P of the hydrogen production unit is equal to the average power of renewable energy power generation in a typical period (day, month, year). 1，H2 The relationship can be obtained according to formula (1-1):

[0129] Q 1，H2 =P / 2.39U Formula (1-1)

[0130] In formula (1-1):

[0131] P——rated power of hydrogen production unit, KW;

[0132] U——Average voltage of the electrolysis chamber of the hydrogen production unit, V.

[0133] In formula (1), the reaction rate R of the methanol synthesis unit is com The determination method is completed using a commercially available micro-tubular reactor system, as follows:

[0134] The micro-tubular reactor filled with catalyst is kept at a set temperature for more than 12 hours, and then the raw gas is introduced according to the set first reaction raw gas flow rate Q (L / kg / h, the volume of gas passing through a certain mass of catalyst per unit time). The catalyst type, reaction raw gas flow rate, raw gas ratio, set temperature, and pressure are the same as those of the actual methanol synthesis unit reaction system of the present invention. The gas concentration at the outlet of the micro-tubular reactor is analyzed by chromatography, and the average carbon dioxide concentration C at the outlet of the micro-tubular reactor within 0-2 hours is recorded. out (mol / L), the reaction rate calculation formula is as follows (1-2):

[0135] R com =Q*(C out -C in ) Formula (1-2)

[0136] In formula (1-2):

[0137] Q——the set first reaction raw gas flow rate, L / kg / h;

[0138] C out ——Average concentration of carbon dioxide at the outlet of the micro-tubular reactor, mol / L;

[0139] C in ——Average carbon dioxide concentration at the inlet of the micro-tubular reactor, mol / L.

[0140] The catalyst loading of the catalyst regeneration unit 3 is calculated according to formula (3):

[0141] m2=m1*Q 1,H2 / Q 3,H2 *R d / R g Formula (3)

[0142] In formula (3):

[0143] m2——catalyst loading in catalyst regeneration unit, kg;

[0144] m1——catalyst loading of methanol synthesis unit, kg;

[0145] Q 1,H2 ——Hydrogen production of the hydrogen production unit, mol / h;

[0146] Q 3,H2 ——Hydrogen flow rate entering the catalyst regeneration unit, mol / h;

[0147] R d ——catalyst deactivation rate, h -1 ;

[0148] R g——Catalyst regeneration rate, h -1 .

[0149] In formula (3), Q 1,H2 The ratio of the hydrogen flow rate to the catalyst regeneration unit 3 is between 2-10, preferably 4-7, for example 5.5. The hydrogen flow rate entering the catalyst regeneration unit 3 is determined based on the balance between the regeneration effect and the power consumption of hydrogen transportation. The larger the hydrogen flow rate, the better the regeneration effect, but the power consumption of hydrogen transportation increases; the smaller the hydrogen flow rate, the smaller the power consumption of hydrogen transportation, but the regeneration effect becomes worse. In the actual calculation process, Q can be calculated first 1,H2 , and then calculate the hydrogen flow rate Q entering the catalyst regeneration unit 3 according to the ratio of the hydrogen flow rate entering the catalyst regeneration unit 3 3,H2 .

[0150] In formula (3), the catalyst deactivation rate is the decrease in the reaction activity per unit time under the reaction conditions of the methanol synthesis unit 2 (hydrogen to carbon dioxide flow ratio, reaction temperature). Since the methanol synthesis conversion rate is maintained at a high level, in formula (3), the catalyst deactivation rate can be considered to be a constant, for example, 0.005-0.05d -1 Similarly, in formula (3), the catalyst regeneration rate is the increase in the reaction activity per unit time under the reaction conditions (hydrogen flow rate, reaction temperature) of the catalyst regeneration unit 3. Since the methanol synthesis conversion rate is maintained at a high level, in formula (3), the catalyst regeneration rate can be considered to be a constant, such as 0.025-0.25d -1 .

[0151] In formula (3), the catalyst deactivation rate R d and catalyst regeneration rate R g The determination method is completed using a commercially available micro-tubular reactor system, as follows:

[0152] Catalyst deactivation rate R d :The micro-tubular reactor filled with catalyst is kept at a constant temperature for more than 12 hours at a set temperature, and then the raw gas is introduced according to the set second reaction raw gas flow rate Q' (L / kg / h, the volume of gas passing through a certain mass of catalyst per unit time). The catalyst type, raw gas ratio, set temperature and pressure are the same as the reaction system of the actual methanol synthesis unit of the present invention. The gas concentration at the outlet of the micro-tubular reactor is analyzed by chromatography, and the carbon dioxide concentration C at the outlet of the micro-tubular reactor at time t is recorded. T (mol / L), calculate the methanol synthesis reaction rate R at time t com,t The catalyst deactivation rate calculation formula is as follows (3-1):

[0153] R d =Q / Q'*(R com,0 -Rcom,t ) / R com,0 / T formula (3-1)

[0154] In formula (3-1),

[0155] Q——the set first reaction raw gas flow rate, L / kg / h (same as formula (1-2));

[0156] Q'——set second reaction raw gas flow rate, L / kg / h;

[0157] R com,0 ——The methanol synthesis reaction rate corresponding to the carbon dioxide concentration (e.g., C0) at the outlet of the micro-tubular reactor at the initial time of the reaction, calculated according to formula (1-2), mol / kg / h;

[0158] R com,t ——The methanol synthesis reaction rate corresponding to the carbon dioxide concentration at the outlet of the micro-tubular reactor at time t, calculated according to formula (1-2), mol / kg / h;

[0159] T——reaction time from initial moment to moment t, d -1 .

[0160] In order to accelerate the deactivation reaction, the set second reaction raw material gas flow rate Q' can take a larger value, such as 10-20 times of the actual reaction flow rate.

[0161] Catalyst regeneration rate R g : The micro-tubular reactor filled with catalyst is kept at a set temperature for more than 12 hours, and then the third reaction raw material gas (i.e. hydrogen) flow rate Q is set. g The catalyst type, purity of the raw gas (i.e., hydrogen), set temperature, and pressure are the same as those of the actual catalyst regeneration system of the present invention. The catalysts after different regeneration times t' are tested in the same system as the methanol synthesis reaction system for reaction rate R' com,t’ , the catalyst regeneration rate calculation formula is as follows (3-2):

[0162] R g =(R' com,t’ -R' com,0 ) / R' com,0 / T' formula (3-2)

[0163] In formula (3-2):

[0164] R' com,0 ——The methanol synthesis reaction rate corresponding to the carbon dioxide concentration at the outlet of the micro-tubular reactor at the initial time of the reaction, calculated according to formula (1-2), mol / kg / h;

[0165] R' com,t’ ——The methanol synthesis reaction rate corresponding to the carbon dioxide concentration at the outlet of the micro-tubular reactor at time t', calculated according to formula (1-2), mol / kg / h;

[0166] T'——reaction time from the initial moment to moment t', d -1 .

[0167] Among them, the production capacity of the methanol synthesis unit 2 matches the production capacity of the hydrogen production unit 1. Specifically, the rated hydrogen production of the hydrogen production unit 1 is equal to the hydrogen consumption of the methanol synthesis unit 2 under the designed working conditions. In the present invention, although part of the hydrogen produced by the hydrogen production unit enters the methanol synthesis unit and part enters the catalyst regeneration unit, the hydrogen entering the catalyst regeneration unit mainly plays the role of carrier gas, and its consumption is very limited and can be ignored; and the hydrogen from the catalyst regeneration unit returns to the methanol synthesis unit again. Therefore, it can be considered that the hydrogen produced by the hydrogen production unit is all used for methanol synthesis, that is, the total amount of hydrogen entering the methanol synthesis unit is the hydrogen production of the hydrogen production unit, and the calculation formula of the catalyst loading of the methanol synthesis unit is Q in formula (1) 1，H2 And the catalyst loading calculation formula of the catalyst regeneration unit Q in formula (3) 1，H2 They can all be considered as the hydrogen production of the hydrogen production unit. In actual calculations, the rated production of the hydrogen production unit can be used as the hydrogen production of the hydrogen production unit and substituted into formulas (1) and (3) for calculation.

[0168] The hydrogen production of the hydrogen production unit 1 can be adjusted within a certain range (for alkaline electrolyzers, 20-110% of the rated production, such as 60%; for proton exchange membrane electrolyzers, 5-120% of the rated production, such as 70%), and the hydrogen consumption of the methanol synthesis unit 2 can be adjusted accordingly with the hydrogen production of the hydrogen production unit 1, so as to achieve intermittent matching with the renewable energy in the renewable energy power generation system connected to the electrolytic hydrogen production system. By following the power output of renewable energy, fluctuations can be smoothed, the auxiliary service function of the power grid can be met, and additional benefits can be achieved. At the same time, the frequency of catalyst particle replacement between the methanol synthesis unit 2 and the catalyst regeneration unit 3 is adjusted (controlled by the calculation program combined with the catalyst particle state detection results), so as to achieve a stable methanol synthesis conversion rate.

[0169] The judgment standard for the catalyst in the methanol synthesis unit 2 to reach the replacement state is that the catalyst activity reaches a preset catalyst replacement value, and the preset catalyst replacement value is 90-95%, such as 92.5%. The catalyst activity in the methanol synthesis unit 2 can be indirectly judged by the methanol synthesis conversion rate. When the activity of the catalyst particles reaches the preset catalyst replacement value, the actual synthesis conversion rate of methanol synthesis is the product of the preset catalyst replacement value and the target methanol synthesis conversion rate, that is, formula (3-3):

[0170] S'=a1*S Formula (3-3)

[0171] In formula (3-3):

[0172] S'——actual methanol synthesis conversion rate, %;

[0173] a1——preset catalyst replacement value, %;

[0174] S——target methanol synthesis conversion rate, %.

[0175] The actual methanol synthesis conversion rate is calculated by sampling and analyzing the outlet methanol concentration through chromatography and other methods.

[0176] The catalyst regeneration unit 3 completes the catalyst regeneration. The catalyst activity in the catalyst regeneration unit reaches the catalyst regeneration value, which is 95-100%, such as 97.5%. The activity of the catalyst can be determined by performing a reaction kinetic test on the catalyst sample. The specific test method is a well-known method and will not be described in detail here.

[0177] The time required for the catalyst regeneration unit 3 to complete the catalyst regeneration is calculated according to formula (4):

[0178] t=(a2-a1) / R g Formula (4)

[0179] In formula (4):

[0180] t——the time when the catalyst regeneration unit completes the catalyst regeneration, d;

[0181] a1——preset catalyst replacement value, 90-95%, preferably 92.5%;

[0182] a2——catalyst regeneration value, 95-100%, preferably 97.5%, and a2>a1;

[0183] R g ——Catalyst regeneration rate, h -1 .

[0184] The reaction gas of the catalyst regeneration unit 3 is high-purity hydrogen (hydrogen purity is 99.999% (volume fraction) or more). The greater the hydrogen flow rate entering the catalyst regeneration unit 3, the greater the catalyst regeneration rate Rg. Therefore, while adapting to the dynamic power input of renewable energy, the frequency of particle replacement between the methanol synthesis unit 2 and the catalyst regeneration unit 3 also changes accordingly, thereby achieving a stable methanol synthesis conversion rate.

[0185] The principle of catalyst regeneration is to heat the catalyst in a hydrogen atmosphere to reduce the metal oxidized during the catalytic process and restore its activity.

[0186] It should be noted that the methanol synthesis unit in the system and method of the embodiment of the present invention can also be replaced by other hydrogenation reaction systems, such as synthetic ammonia, carbon dioxide hydrogenation to carbon monoxide, biomass hydrogenation conversion, etc.; accordingly, the type of catalyst, the conditions for synthesizing organic matter, the catalyst regeneration conditions, etc. can be adaptively adjusted.

[0187] The green methanol production system and method of the present invention are described below with reference to specific embodiments.

[0188] Example 1

[0189] like Figure 2 As shown, the green methanol production system of the embodiment of the present invention includes a hydrogen production unit 1, a methanol synthesis unit 2, a catalyst regeneration unit 3 and a boiler 4.

[0190] The hydrogen production unit 1 is used to obtain hydrogen and oxygen; the hydrogen production unit adopts the existing alkaline water electrolysis hydrogen production system, in which the electrolyzer is a conventional 1000Nm 3 / h alkaline electrolyzer, the hydrogen production unit is electrically connected to the existing wind power generation system to obtain electricity for electrolyzing water to produce hydrogen.

[0191] The methanol synthesis unit 2 adopts the gas-solid reaction equipment commonly used in industry, which mainly includes a first fluidized bed reactor and matching pipeline accessories. The interconnection relationship between the first fluidized bed reactor and the matching pipeline accessories is the existing technology and will not be repeated. The first fluidized bed reactor is provided with a first hydrogen inlet, a first steam inlet and a carbon dioxide inlet at the bottom, and a catalyst inlet and a catalyst outlet at the upper end. The first hydrogen inlet is connected to the hydrogen outlet of the electrolyzer of the hydrogen production unit 1 through a first pipeline; one end of the first steam inlet is connected to the inlet of the heat exchange coil in the first fluidized bed reactor, and the other end is connected to the steam outlet of the boiler through a second pipeline.

[0192] The catalyst regeneration unit 3 adopts the gas-solid reaction equipment commonly used in industry, which mainly includes a second fluidized bed reactor, a second centrifugal separator and matching pipeline accessories. The interconnection relationship between the second fluidized bed reactor, the second centrifugal separator and the matching pipeline accessories is the existing technology and will not be repeated. The second fluidized bed reactor is provided with a second hydrogen inlet, a second steam inlet and a regenerated catalyst outlet at the bottom, a regenerated catalyst inlet is provided at the lower end, and a second hydrogen outlet is provided at the upper end. The second hydrogen inlet is connected to the hydrogen outlet of the electrolyzer of the hydrogen production unit 1 through the third pipeline, the second steam inlet is connected to the steam outlet of the boiler 4 through the fourth pipeline, the regenerated catalyst inlet is connected to the catalyst outlet through the fifth pipeline, the regenerated catalyst outlet is connected to the catalyst inlet through the sixth pipeline, and the second hydrogen outlet is connected to the first hydrogen inlet (not shown) through the seventh pipeline. Solenoid valves are installed on the first pipeline, the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline, the sixth pipeline and the seventh pipeline, and the sixth pipeline can be connected to an inert gas pipeline such as nitrogen as a carrier gas or a catalyst delivery pump is installed.

[0193] The boiler is installed in the boiler room. Boiler 4 is a waste heat boiler. Its refrigerant inlet is connected to the circulating water pump, and its fuel inlet is connected to the oxygen outlet of the hydrogen production unit. Oxygen is used as a combustion aid to burn and heat cold water to generate high-temperature steam.

[0194] The commercially available catalyst Cu / ZnO2 / Al2O3 is arranged in the first fluidized bed reactor in the methanol synthesis unit 2. After the catalyst is deactivated during methanol synthesis in the methanol synthesis unit, it enters the second fluidized bed reactor in the catalyst regeneration unit 3 for regeneration.

[0195] The method for producing green methanol using the green methanol production system of this embodiment is as follows:

[0196] The hydrogen production unit 1 produces 44.6 kmol / h of hydrogen, of which 80% directly enters the methanol synthesis unit 2 as raw gas to react with carbon dioxide under the action of a catalyst to produce methanol, and 20% enters the catalyst regeneration unit 3 to participate in the regeneration of the deactivated catalyst from the methanol synthesis unit 2.

[0197] The oxygen output of hydrogen production unit 1 is 22.3 kmol / h, which enters the boiler room of the production area and serves as a combustion aid for the waste heat boiler to assist in generating high-temperature steam. The high-temperature steam enters the heat exchange coils of the first fluidized bed reactor and the heat exchange coils of the second fluidized bed reactor respectively as a high-temperature heat exchange medium to assist in generating the reaction temperature required for methanol synthesis and catalyst regeneration.

[0198] The hydrogen flowing out of the catalyst regeneration unit 3 and the obtained regenerated catalyst re-enter the methanol synthesis unit 2 to participate in the methanol synthesis reaction.

[0199] Throughout the production process:

[0200] The process parameters of hydrogen production by electrolysis of water are: temperature 80℃, working pressure 1.6MPa, chamber voltage 1.6-2.0V, current density 2000-4000A / m 2 .

[0201] Hydrogen production unit Q 1,H2 The hydrogen production of the hydrogen production unit is matched with the power generation of renewable energy to obtain a certain renewable energy power generation and consumption effect. For example, the rated power P of the hydrogen production unit is equal to the average power of renewable energy power generation in a typical period (day, month, year). 1，H2 The relationship can be calculated according to formula (1-1). For example, in this embodiment, when P = 191.87KW, the average voltage of the electrolysis chamber of the instantaneous hydrogen production unit U = 1.8V, the hydrogen production Q of the hydrogen production unit can be calculated according to formula (1-1): 1,H2 It is 44.6.

[0202] The process parameters for synthesizing methanol from hydrogen and carbon dioxide in the presence of a catalyst are as follows: reaction temperature 250°C, reaction pressure 4 MPa, reaction space velocity 10,000 h -1 The total flow rate of raw hydrogen entering the methanol synthesis unit (consisting of hydrogen from the hydrogen production unit and hydrogen from the catalyst regeneration unit, and the value is equal to the hydrogen output of the hydrogen production unit) is 44.6 kmol / h, the flow rate of carbon dioxide is 11.89 mol / h, the flow ratio n of raw hydrogen and carbon dioxide is 3.75, and the reaction rate Rcom is 6.7 mol / kg / h; the molar flow rate of carbon dioxide flowing out of the methanol synthesis unit is 9.51 mol / h; the target methanol synthesis conversion rate S is 20% (calculated according to formula (2)).

[0203] Catalyst regeneration unit The process parameters of catalyst regeneration are: reaction temperature is 250℃, reaction pressure is 1.6MPa, reaction space velocity is 10000h -1 , the catalyst deactivation rate Rd is 0.01d -1 , the catalyst regeneration rate Rg is 0.045d -1 ; Hydrogen flow rate Q entering the catalyst regeneration unit 3,H2 It is 9.91kmol / h.

[0204] According to formula (1), the catalyst loading m1 of the methanol synthesis unit is calculated to be 332 kg.

[0205] Q 1,H2 / Q 3,H2=4.5; The catalyst loading m2 of the catalyst regeneration unit is calculated according to formula (3) to be 332 kg.

[0206] The judgment standard for the catalyst particles in the methanol synthesis unit to reach the replacement state is: the activity of the catalyst particles reaches 95% of the preset catalyst replacement value (a1 in formula (4)). The activity of the catalyst in the methanol synthesis unit can be indirectly judged by the methanol synthesis conversion rate. When the activity of the catalyst particles reaches 95% of the preset catalyst replacement value, the actual methanol synthesis conversion rate reaches 19%. The actual methanol synthesis conversion rate is calculated by sampling and analyzing the outlet carbon dioxide concentration through chromatography and other methods.

[0207] The criterion for judging whether the catalyst particles in the catalyst regeneration unit have completed regeneration is that the activity of the catalyst particles reaches 100% of the catalyst regeneration value (a2 in formula (4)). The activity of the catalyst particles can be determined by performing a reaction kinetic test on a catalyst sample. The time t for completing regeneration calculated according to formula (4) is 1.11, that is, under rated production conditions, the catalyst needs to be replaced once between the methanol synthesis unit and the catalyst regeneration unit every 1.11 days.

[0208] Under rated production conditions, the wind power input of the wind power generation system is 5MW.

[0209] When the wind power fluctuates, the hydrogen production flow rate of the hydrogen production unit 1 changes proportionally with the wind power. The specific relationship is shown in formula (1-1).

[0210] When the temperature and pressure remain unchanged, R d / R g =0.01 / 0.045=10 / 45, at this time, by adjusting Q 1,H2 / Q 3,H2 、m2(m2=m1*Q 1,H2 / Q 3,H2 *R d / R g ), the methanol conversion rate can be maintained at 20%. Thus, flexible wind power consumption can be achieved while maintaining a certain methanol conversion rate.

[0211] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0212] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0213] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0214] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0215] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0216] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A green methanol production system, characterized in that: include: A hydrogen production unit, wherein the hydrogen production unit is used to obtain hydrogen and oxygen; A methanol synthesis unit, wherein the methanol synthesis unit has a first hydrogen inlet, a carbon dioxide inlet, a catalyst inlet and a catalyst outlet, and the first hydrogen inlet is connected to the hydrogen outlet of the hydrogen production unit; a catalyst regeneration unit, the catalyst regeneration unit having a second hydrogen inlet, a regenerated catalyst inlet, a regenerated catalyst outlet and a second hydrogen outlet, the second hydrogen inlet being connected to the hydrogen outlet of the hydrogen production unit, the regenerated catalyst inlet being connected to the catalyst outlet, the regenerated catalyst outlet being connected to the catalyst inlet, and the second hydrogen outlet being connected to the first hydrogen inlet; A boiler, wherein a fuel inlet of the boiler is connected to an oxygen outlet of the hydrogen production unit, and a steam outlet of the boiler is connected to a first steam inlet of the methanol synthesis unit and a second steam inlet of the catalyst regeneration unit; The hydrogen production unit adopts a water electrolysis hydrogen production system or a photolysis water hydrogen production system; the water electrolysis hydrogen production system is electrically connected to a renewable energy power generation system; the water electrolysis hydrogen production system is one or more of an alkaline water electrolysis hydrogen production system, a proton exchange membrane water electrolysis hydrogen production system, an alkaline ion membrane water electrolysis hydrogen production system or a high-temperature solid oxide water electrolysis hydrogen production system; The methanol synthesis unit and the catalyst regeneration unit are both gas-solid reaction equipment; the gas-solid reaction equipment includes a reactor; The reactor is a fixed bed reactor, a fluidized bed reactor or a batch fully mixed reactor.

2. The green methanol production system according to claim 1, characterized in that: The catalyst is a catalyst for producing methanol by hydrogenating carbon dioxide.

3. The green methanol production system according to claim 2, characterized in that: The catalyst is a metal dispersed on the surface of a carbon-based or metal oxide-based support.

4. The green methanol production system according to claim 2, characterized in that: The catalyst is one of Cu / ZnO / Al2O3, Cu / CeO2, and Cu / ZnO / SiO2.

5. The green methanol production system according to claim 1, characterized in that: The reactor in the methanol synthesis unit has the first hydrogen inlet, the carbon dioxide inlet, the catalyst inlet and the catalyst outlet; The reactor in the catalyst regeneration unit has the second hydrogen inlet, the regenerated catalyst inlet, the regenerated catalyst outlet and the second hydrogen outlet.

6. The green methanol production system according to claim 5, characterized in that: The catalyst outlet is located at the upper end of the reactor in the methanol synthesis unit, and the regenerated catalyst inlet is located at the lower end of the reactor in the catalyst regeneration unit.

7. A green methanol production method, applied to the green methanol production system according to any one of claims 1 to 6, characterized in that: include A portion of the hydrogen produced by the hydrogen production unit is used as feed gas to enter the methanol synthesis unit to react with carbon dioxide under the action of a catalyst to generate methanol, and the other portion enters the catalyst regeneration unit to participate in the regeneration of the deactivated catalyst from the methanol synthesis unit; The hydrogen flowing out of the catalyst regeneration unit and the obtained regenerated catalyst re-enter the methanol synthesis unit to participate in the methanol synthesis reaction.

8. The green methanol production method according to claim 7, characterized in that: Also includes: The oxygen produced by the hydrogen production unit enters the boiler to assist combustion and produce steam, which serves as a heat exchange medium to help generate the temperature required for methanol synthesis and catalyst regeneration.

9. The green methanol production method according to claim 7 or 8, characterized in that: The rated hydrogen production of the hydrogen production unit is equal to the hydrogen consumption of the methanol synthesis unit under the designed working conditions.

10. The green methanol production method according to claim 7 or 8, characterized in that: The reaction temperatures of the methanol synthesis unit and the catalyst regeneration unit are both 200-400°C; The reaction pressure of the methanol synthesis unit is 1-7 MPa, and the reaction pressure of the catalyst regeneration unit is 0.1-10 MPa.

11. The green methanol production method according to claim 7 or 8, characterized in that: The catalyst loading of the methanol synthesis unit is calculated as follows: m1=SQ 1，H2 / nR com Where: m1——catalyst loading of methanol synthesis unit, kg; Q 1，H2 ——Hydrogen production of the hydrogen production unit, mol / h; S——target methanol synthesis conversion rate, %; n——the flow ratio of all hydrogen and carbon dioxide entering the methanol synthesis unit; R com ——Reaction rate of methanol synthesis unit, mol / kg / h.

12. The green methanol production method according to claim 11, characterized in that: The target methanol synthesis conversion rate is calculated as follows: S=[N(in)-N(out)] / N(in) Where: N(in)——the molar flow rate of carbon dioxide entering the methanol synthesis unit, mol / h; N(out) ——molar flow rate of carbon dioxide flowing out of the methanol synthesis unit, mol / h.

13. The green methanol production method according to claim 11 or 12, characterized in that: The reaction rate of the methanol synthesis unit is the number of moles of methanol produced per kilogram of catalyst particle surface per unit time; The flow ratio of hydrogen to carbon dioxide entering the methanol synthesis unit is 3-10; The target methanol synthesis conversion rate is 10-30%.

14. The green methanol production method according to claim 13, characterized in that: The flow ratio of hydrogen to carbon dioxide entering the methanol synthesis unit is 3-4.

15. The green methanol production method according to claim 11, characterized in that: The catalyst loading of the catalyst regeneration unit is calculated as follows: m2=m1* Q 1,H2 / Q 3,H2 *R d / R g Where: m2——catalyst loading in catalyst regeneration unit, kg; m1——catalyst loading of methanol synthesis unit, kg; Q 1,H2 ——Hydrogen production of the hydrogen production unit, mol / h; Q 3,H2 ——Hydrogen flow rate entering the catalyst regeneration unit, mol / h; R d ——catalyst deactivation rate, h -1 ; R g ——Catalyst regeneration rate, h -1 .

16. The green methanol production method according to claim 13, characterized in that: The ratio of the hydrogen production of the hydrogen production unit to the hydrogen flow entering the catalyst regeneration unit is between 2-10.

17. The green methanol production method according to claim 7 or 8, characterized in that: The judgment standard for the catalyst in the methanol synthesis unit to reach the replacement state is that the catalyst activity reaches a preset catalyst replacement value, and the preset catalyst replacement value is 90-95%; The conversion rate of methanol synthesis is the product of the preset catalyst replacement value and the target methanol synthesis conversion rate.

18. The green methanol production method according to claim 7 or 8, characterized in that: The criterion for judging whether the catalyst regeneration unit has completed catalyst regeneration is that the catalyst activity in the catalyst regeneration unit reaches the catalyst regeneration value, and the regeneration value is 95-100%; The time for the catalyst regeneration unit to complete catalyst regeneration is calculated as follows: t=(a2-a1) / R g Where: t——the time when the catalyst regeneration unit completes the catalyst regeneration, d; a1——preset catalyst replacement value, 90-95%; a2——catalyst regeneration value, 95-100%, and a2>a1; R g ——Catalyst regeneration rate, h -1 .

Images