Chemical looping hydrogen production system and method for absorbing and trapping carbon dioxide by coupling solvent

Abstract

The invention relates to the technical field of chemical-looping hydrogen production, in particular to a chemical-looping hydrogen production system and method for absorbing and trapping carbon dioxide through a coupling solvent. The invention discloses a chemical looping hydrogen production system for absorbing and trapping carbon dioxide by coupling a solvent. The chemical looping hydrogen production system comprises an air oxidation reaction unit, a reduction reaction unit, a hydrogen extraction unit, a solvent absorption decarburization unit and an oxygen carrier circulating feeding unit, the solvent absorption decarburization unit comprises a solvent absorption device and a solvent regeneration device; the air oxidation reaction unit comprises an air oxidation reaction device; the reduction reaction unit comprises a reduction reaction device; the hydrogen extraction unit comprises a PSA hydrogen extraction device; the oxygen carrier circulating feeding unit comprises a separating device, a dust removing device, a dust collecting device, a lifting pipe and a particle lifting device. The system can realize 100% conversion of raw materials and 100% capture of carbon dioxide, the obtained carbon dioxide is high in purity, the hydrogen production rate of unit methane is high, the energy consumption is low, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical chain hydrogen production, and in particular to a chemical chain hydrogen production system and method for coupling solvent absorption and capture of carbon dioxide. Background Art

[0002] Hydrogen is an important process raw material for refineries and is widely used in gasoline, diesel, and residual oil hydrogenation processes to adjust the hydrogen-carbon ratio of products and desulfurize and denitrogenate. At present, crude oil is becoming seriously heavy and inferior. For large refineries, hydrocracking and hydrotreating process routes are conducive to "using up" the raw materials in the processing of heavy and inferior crude oil, and the benefits are better than the coking route. With the continuous acceleration of oil quality upgrades, the demand for hydrogen in refineries is increasing rapidly.

[0003] The main process technology for producing hydrogen from natural gas in industry is steam reforming (SMR). Steam reforming refers to the process of reacting hydrocarbons such as methane with water vapor in the presence of a catalyst and at high temperature to generate synthesis gas, and then further converting the CO in the synthesis gas into hydrogen and CO2 through a shift reaction. Finally, the residual CH4, CO, CO2 and H2O in the synthesis gas are removed by pressure swing adsorption to obtain high-purity hydrogen, and the desorbed gas is used as fuel for the reformer.

[0004] The problems of producing hydrogen using the traditional steam reforming (SMR) process include: (1) The steam reforming reaction temperature is high, reaching 800-950°C, which places stringent requirements on the material of the reactor; (2) The raw gas conversion rate is low, with a primary conversion rate of about 70%-75%, and the remaining 25%-30% of methane enters the desorption gas as fuel for the reformer; (3) In addition to the natural gas used as raw material, the device also needs to supplement some natural gas as fuel for the reformer; (4) Carbon dioxide is emitted into the atmosphere through the chimney through the flue gas. The concentration of carbon dioxide in the flue gas is low (10%-15%), which makes it difficult to capture and consumes a lot of energy. It also requires increased investment in the SMR device.

[0005] Chemical chain hydrogen production is the most promising hydrogen production technology for industrialization, but the existing chemical chain hydrogen production is a high-temperature reaction of 850-950°C. High temperature can accelerate the reaction rate, but high temperature will place stringent requirements on the reactor material, pipelines and valves. If the reaction temperature is lowered, methane cannot be completely converted into carbon dioxide, and the conversion rate is low. In addition, the energy consumption is high.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] One object of the present invention is to provide a chemical chain hydrogen production system for coupling solvent absorption and capture of carbon dioxide, which can solve the above-mentioned technical problems, achieve 100% conversion of raw materials, 100% capture of carbon dioxide, the purity of carbon dioxide is not less than 98%, the hydrogen production rate per unit methane is high, the energy consumption is low, and the cost is low.

[0008] Another object of the present invention is to provide a chemical chain hydrogen production method for coupling solvent absorption and capture of carbon dioxide, which can achieve high conversion rate of raw materials, high capture rate of carbon dioxide, high purity carbon dioxide, and high hydrogen production rate per unit methane.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] A chemical chain hydrogen production system for coupling solvent absorption and capture of carbon dioxide comprises an air oxidation reaction unit, a reduction reaction unit, a hydrogen extraction unit, a solvent absorption and decarbonization unit and an oxygen carrier circulation and feeding unit; the air oxidation reaction unit comprises an air oxidation reaction device, the air oxidation reaction device is used to obtain an oxidized oxygen carrier and hot oxygen-poor air; the reduction reaction unit comprises a reduction reaction device, the reduction reaction device is used to mix a mixed raw gas with the oxidized oxygen carrier to obtain a synthesis gas and a reduced oxygen carrier; the solvent absorption and decarbonization unit comprises a solvent absorption device and a solvent regeneration device, the solvent absorption device is used to absorb carbon dioxide in the synthesis gas to obtain a mixed gas and a rich solvent, the solvent regeneration device is used to desorb carbon dioxide in the rich solvent and form a lean solvent; the hydrogen extraction unit comprises a hydrogen extraction device, the hydrogen extraction device is used to purify hydrogen and obtain desorbed gas; the oxygen carrier circulation and feeding unit is used to provide the air oxidation reaction device with a reduced oxygen carrier, and to realize the transportation and flow control of the reduced oxygen carrier from bottom to top.

[0011] In some embodiments, the oxygen carrier circulation feeding unit includes a separation device, a dust removal device, a dust collection device, a lifting pipe and a particle lifting device; the particle lifting device is connected to the first feed port of the separation device through the lifting pipe; the first discharge port of the separation device is connected to the feed port of the air oxidation reaction device; the second discharge port of the separation device is respectively connected to the feed port of the particle lifting device and the feed port of the dust removal device through the dust collection device, and the discharge port of the dust removal device is connected to the second feed port of the separation device.

[0012] In some embodiments, the solvent absorption decarbonization unit also includes a cooling device and a reboiler; the cooling device is used to cool the synthesis gas; the reboiler is connected to the solvent regeneration device; the gas outlet of the solvent absorption device is connected to the feed inlet of the hydrogen extraction device; the liquid outlet of the solvent absorption device is connected to the feed inlet of the solvent regeneration device; the liquid inlet of the solvent absorption device is connected to the lean solvent supply source; the solvent regeneration device also includes a carbon dioxide outlet and a liquid phase outlet, and the liquid phase outlet is connected to the lean solvent supply source or the liquid inlet of the solvent absorption device.

[0013] In some embodiments, the air oxidation reaction unit also includes a first heat exchange device and a compressed air source, the compressed air source is connected to the gas inlet of the air oxidation reaction unit through the first heat exchange device; the gas outlet of the air oxidation reaction device is connected to the reboiler through the first heat exchange device; the feed inlet of the air oxidation reaction device is connected to the feed outlet of the separation device.

[0014] In some embodiments, the reduction reaction unit further includes a second heat exchange device and a mixed raw gas supply source, wherein the mixed raw gas supply source is connected to the gas inlet of the reduction reaction device through the second heat exchange device; the feed inlet of the reduction reaction device is connected to the discharge port of the air oxidation reaction device; the discharge port of the reduction reaction device is connected to the riser of the oxygen carrier circulation feed unit; and the gas outlet of the reduction reaction device is connected to the solvent absorption device through the second heat exchange device and the cooling device.

[0015] In some embodiments, the hydrogen extraction device includes a PSA hydrogen extraction device, which is provided with a hydrogen outlet and a desorption gas outlet; the desorption gas outlet is connected to the mixed raw gas supply source; the hydrogen extraction unit also includes a crude hydrogen compression device, and the gas outlet of the solvent absorption device is connected to the hydrogen extraction device through the crude hydrogen compression device.

[0016] A method for producing hydrogen by chemical chaining by coupling solvent absorption and capturing carbon dioxide, using the chemical chaining hydrogen production system by coupling solvent absorption and capturing carbon dioxide, comprising the following steps:

[0017] The separation device in the oxygen carrier circulation feeding unit provides the reduced oxygen carrier to the air oxidation reaction device of the air oxidation reaction unit, and performs air oxidation reaction with compressed air to form oxidized oxygen carrier and hot oxygen-depleted air; the oxidized oxygen carrier enters the reduction reaction device of the reduction reaction unit, and performs reduction reaction with the mixed raw gas to form synthesis gas and reduced oxygen carrier; the reduced oxygen carrier formed in the reduction reaction device is lifted to the separation device through the lifting pipe under the action of the particle lifting device for separation treatment to obtain purified reduced oxygen carrier and dust gas phase; the synthesis gas enters the solvent absorption device of the solvent absorption decarbonization unit, and absorbs carbon dioxide after mixing with the lean solvent to obtain a mixed gas and a rich solvent; the mixed gas enters the hydrogen extraction device of the hydrogen extraction unit for hydrogen purification to obtain high-purity hydrogen and desorbed gas, and the desorbed gas flows back to the reduction reaction device; the rich solvent enters the solvent regeneration device for carbon dioxide desorption to obtain high-concentration carbon dioxide and regenerated lean solvent, and the regenerated lean solvent flows back to the solvent absorption device.

[0018] In some embodiments, the hot oxygen-depleted air and the compressed air provided by the compressed air source are heat exchanged through a first heat exchange device, and the compressed air is heated up and enters the air oxidation reaction device. The hot oxygen-depleted air is cooled down and enters the reboiler to provide heat to heat the liquid phase in the solvent regeneration device.

[0019] In some embodiments, the mixed raw gas and the synthesis gas formed by the reduction reaction device are heat exchanged in a second heat exchange device, and the synthesis gas is cooled and then enters the cooling device for cooling, and then enters the solvent absorption device, and the mixed raw gas is heated and then enters the reduction reaction device.

[0020] In some embodiments, the dust gas phase enters a dust collection device for dust removal, part of the gas after dust removal passes through a particle lifting device as lifting gas, and the remaining gas enters a dust removal device for dust removal and then serves as dust removal gas for a separation device.

[0021] In some embodiments, the mixed gas is first compressed by a crude hydrogen compression device before entering the hydrogen extraction device for hydrogen purification.

[0022] In some embodiments, the temperature of the air oxidation reaction is 650-800° C., and the pressure of the air oxidation reaction is normal pressure to 2.0 MPag.

[0023] In some embodiments, the temperature of the reduction reaction is 500-650° C., and the pressure of the reduction reaction is normal pressure to 2.0 MPag.

[0024] In some embodiments, the mixed raw gas includes raw gas and water vapor, the raw gas includes methane or natural gas, and the water-to-carbon ratio of water vapor to raw gas is 1-3.

[0025] In some embodiments, in the method, the capture rate of carbon dioxide is 100%; and the concentration of the high-concentration carbon dioxide is greater than 98%.

[0026] In some embodiments, in the method, the hydrogen production rate per unit of methane is 2.6 Nm 3 / Nm 3 More than methane.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The system of the present invention can achieve 100% conversion of raw materials and 100% capture of carbon dioxide with a purity of not less than 98% through the coordination of various units; the hydrogen production rate per unit of methane is high; the required heat in the reduction reaction device is supplied by the heat released by the reaction materials in the air oxidation reaction device, and the heat is carried by the movement of oxygen carriers. The device can achieve self-heating balance and does not require external fuel; the material of high-temperature equipment can be effectively reduced, and energy consumption and investment can be reduced.

[0029] (2) The method of the present invention can achieve 100% conversion of raw materials through the coordination of various steps, achieve a carbon dioxide capture rate of 100%, and a purity of not less than 98%; the heat required for the reduction reaction is supplied by the heat released by the air oxidation reaction, and the heat is carried by the movement of the oxygen carrier. The device can achieve self-heating balance and does not require external fuel; the reduction reaction adopts a lower temperature, which is much lower than the reaction temperature under conventional process conditions; the reaction product is used to preheat the reactant, the heat of the reaction product is recovered, and the oxygen-depleted air is used as the solvent heat source to reduce energy consumption and cost; the hydrogen production rate per unit of methane can reach 2.6Nm 3 / Nm 3 More than methane. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a schematic diagram of a chemical chain hydrogen production system for capturing carbon dioxide by coupling solvent absorption according to the present invention.

[0032] Reference numerals:

[0033] 1-separation device, 2-dust collection device, 3-particle lifting device, 4-lifting pipe, 5-dust removal device, 6-air oxidation reaction device, 7-first heat exchange device, 8-reduction reaction device, 9-second heat exchange device, 10-cooling device, 11-solvent absorption device, 12-solvent regeneration device, 13-reboiling device, 14-crude hydrogen compression device, 15-PSA hydrogen extraction device. DETAILED DESCRIPTION

[0034] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] According to one aspect of the present invention, the present invention relates to a chemical chain hydrogen production system for coupling solvent absorption and capture of carbon dioxide, comprising an air oxidation reaction unit, a reduction reaction unit, a hydrogen extraction unit, a solvent absorption and decarbonization unit, and an oxygen carrier circulation and feeding unit. The air oxidation reaction unit comprises an air oxidation reaction device, which is used to obtain an oxidized oxygen carrier and hot oxygen-poor air; the reduction reaction unit comprises a reduction reaction device, which is used to mix the mixed raw gas with the oxidized oxygen carrier to obtain synthesis gas and reduced oxygen carrier; the solvent absorption and decarbonization unit comprises a solvent absorption device and a solvent regeneration device, the solvent absorption device is used to absorb carbon dioxide in the synthesis gas to obtain a mixed gas and a rich solvent, and the solvent regeneration device is used to desorb carbon dioxide in the rich solvent and form a lean solvent; the hydrogen extraction unit comprises a hydrogen extraction device, which is used to purify hydrogen and obtain desorbed gas; the oxygen carrier circulation and feeding unit is used to provide reduced oxygen carriers for the air oxidation reaction device, and to realize the transportation and flow control of the reduced oxygen carriers from bottom to top.

[0038] The system of the present invention can achieve 100% conversion of raw materials and 100% capture of carbon dioxide with a purity of not less than 98% (v) through the coordination of various units; the required heat in the reduction reaction device is supplied by the heat released by the reaction materials in the air oxidation reaction device, and the heat is carried by the movement of the oxygen carrier. The device can achieve self-heating balance and does not require external fuel; the hydrogen production rate per unit of methane can reach 2.6Nm 3 / Nm 3 Methane and above; can effectively reduce the material of high-temperature equipment, reduce energy consumption and investment.

[0039] In some embodiments, the oxygen carrier circulation feeding unit includes a separation device, a dust removal device, a dust collection device, a lifting pipe and a particle lifting device. The particle lifting device is connected to the first feed port of the separation device through the lifting pipe; the first discharge port of the separation device is connected to the feed port of the air oxidation reaction device; the second discharge port of the separation device is connected to the feed port of the particle lifting device and the feed port of the dust removal device respectively through the dust collection device, and the discharge port of the dust removal device is connected to the second feed port of the separation device. The oxygen carrier circulation feeding unit of the present invention can realize the recycling of oxygen carriers, wherein the separation device is used to provide reduced oxygen carriers. Specifically, the original oxygen carriers formed in the reduction reaction device can be further separated to obtain high-purity reduced oxygen carriers and recycled. The dust collection device is used to collect dust and gas in the dust gas phase obtained after separation by the separation device. Part of the gas is used as the lifting gas of the reduced oxygen carrier through the particle lifting device and the lifting pipe, and the dust removal device is used to remove dust from the remaining gas to serve as the dust removal gas of the separation device.

[0040] In some embodiments, the air oxidation reaction unit further includes a first heat exchange device and a compressed air source, the compressed air source is connected to the gas inlet of the air oxidation reaction unit through the first heat exchange device; the gas outlet of the air oxidation reaction device is connected to the reboiler of the solvent absorption decarbonization unit through the first heat exchange device; the feed inlet of the air oxidation reaction device is connected to the discharge outlet of the separation device. The compressed air source is used to provide compressed air. The reduced oxygen carrier moves from top to bottom in the air oxidation reaction device and contacts with the compressed air in parallel flow. The air oxidation reaction unit of the present invention can realize the oxidation of the reduced carrier to obtain hot oxygen-depleted air and the reduced carrier, and part of the heat of the hot oxygen-depleted air is exchanged through the first heat exchange device and the reboiler to realize the recycling of heat.

[0041] In some embodiments, the reduction reaction unit further includes a second heat exchange device and a mixed raw gas supply source, the mixed raw gas supply source is connected to the gas inlet of the reduction reaction device through the second heat exchange device; the feed port of the reduction reaction device is connected to the discharge port of the air oxidation reaction device; the discharge port of the reduction reaction device is connected to the lifting pipe of the oxygen carrier circulation feeding unit through the discharge pipe. In some embodiments, the lifting pipe has a three-way structure, one port is connected to the separation device, one port is connected to the particle lifting device, and one port is connected to the discharge pipe. The gas outlet of the reduction reaction device is connected to the solvent absorption device through the second heat exchange device and the cooling device of the solvent absorption decarbonization unit. The mixed raw gas supply source is used to provide mixed raw gas, including raw gas and water vapor. In some embodiments, the raw gas and water vapor are each merged through a pipeline to form a mixed raw gas. The present invention can achieve an efficient reduction reaction of the oxidized oxygen carrier and the mixed raw gas through the coordination of each device of the reduction reaction unit to obtain synthesis gas and reduced oxygen carrier, and the reduced oxygen carrier can be further recycled. After the synthesis gas is heat exchanged by the second heat exchange device and cooled by the cooling device, it reaches room temperature.

[0042] In some embodiments, the solvent absorption decarbonization unit further includes a cooling device and a reboiling device; the cooling device is used to cool the synthesis gas, and the first heat exchange device is connected to the solvent absorption device through the cooling device. The reboiling device is connected to the solvent regeneration device, and is arranged at the bottom of the solvent regeneration device to provide heat. The gas outlet of the solvent absorption device is connected to the feed inlet of the hydrogen extraction device; the liquid outlet of the solvent absorption device is connected to the feed inlet of the solvent regeneration device; the liquid inlet of the solvent absorption device is connected to the lean solvent supply source; the solvent regeneration device also includes a carbon dioxide outlet and a liquid phase outlet, and the liquid phase outlet is connected to the lean solvent supply source or the liquid inlet of the solvent absorption device. The solvent absorption decarbonization unit, through the cooperation of various devices, can absorb carbon dioxide from the synthesis gas to obtain a mixed gas and a rich solvent, perform carbon dioxide analysis on the rich solvent to obtain carbon dioxide and a lean solvent, and the lean solvent is further recycled. After the synthesis gas passes through the solvent absorption decarbonization device, more than 90% of the carbon dioxide can be removed, which can effectively reduce the load and investment of the subsequent PSA device.

[0043] In some embodiments, the hydrogen extraction device includes a PSA hydrogen extraction device, which is provided with a hydrogen outlet and a desorbed gas outlet; the desorbed gas outlet is connected to the mixed raw material gas supply source and can be further recycled. The hydrogen extraction unit also includes a crude hydrogen compression device, and the gas outlet of the solvent absorption device is connected to the hydrogen extraction device through the crude hydrogen compression device. The hydrogen extraction unit of the present invention can obtain high-purity hydrogen and desorbed gas, and the desorbed gas can be further recycled and reused. The pressure is slightly positive and circulated into the raw gas pipeline under the action of the ejector, and the incompletely reacted raw material is sent to the reduction reaction device to achieve complete conversion of the raw material.

[0044] In some embodiments, the solvent absorption device and the solvent regeneration device adopt a co-current or counter-current moving bed reactor. In some embodiments, the separation device is a separation hopper. The dust removal device is a dust removal fan. The lifting device is a lifting fan.

[0045] According to another aspect of the present invention, the present invention also relates to a method for producing hydrogen by chemical chaining by coupling solvent absorption and capture of carbon dioxide, using the above-mentioned system, comprising the following steps:

[0046] The separation device in the oxygen carrier circulation feeding unit provides the reduced oxygen carrier to the air oxidation reaction device of the air oxidation reaction unit, and performs air oxidation reaction with compressed air to form oxidized oxygen carrier and hot oxygen-depleted air; the oxidized oxygen carrier enters the reduction reaction device of the reduction reaction unit, and performs reduction reaction with the mixed raw gas to form synthesis gas and reduced oxygen carrier; the reduced oxygen carrier formed in the reduction reaction device is lifted to the separation device through the lifting pipe under the action of the particle lifting device for separation treatment to obtain purified reduced oxygen carrier and dust gas phase (dust and gas phase generated by wear); the synthesis gas enters the solvent absorption device of the solvent absorption decarbonization unit, mixes with the lean solvent and absorbs carbon dioxide to obtain a mixed gas and a rich solvent; the mixed gas enters the hydrogen extraction device of the hydrogen extraction unit for hydrogen purification to obtain high-purity hydrogen and desorbed gas, and the desorbed gas flows back to the reduction reaction device; the rich solvent enters the solvent regeneration device for carbon dioxide desorption to obtain high-concentration carbon dioxide and regenerated lean solvent, and the regenerated lean solvent flows back to the solvent absorption device.

[0047] The method of the present invention can achieve 100% conversion of raw materials through the coordination of various steps, achieve a carbon dioxide capture rate of 100%, and a purity of not less than 98%; the heat required for the reduction reaction is supplied by the heat released by the air oxidation reaction, and the heat is carried by the movement of the oxygen carrier. The device can achieve self-heating balance and no external fuel is required; the reaction product is used to preheat the reactant, the heat of the reaction product is recovered, and the oxygen-deficient air is used as a solvent heat source to reduce energy consumption and cost; the hydrogen production rate per unit of methane can reach 2.6Nm 3 / Nm 3 Above methane, e.g. 2.6Nm 3 / Nm 3 Methane, 2.7Nm 3 / Nm 3 Methane, 2.8Nm 3 / Nm 3 Methane, 3Nm 3 / Nm 3 Methane, etc.

[0048] In some embodiments, the hot oxygen-depleted air and the compressed air provided by the compressed air source are heat exchanged through the first heat exchange device, the compressed air is heated and enters the air oxidation reaction device, and the hot oxygen-depleted air is cooled and enters the reboiler to provide heat to heat the liquid phase in the solvent regeneration device, and is safely discharged after recovering the high-temperature heat. The hot oxygen-depleted air can achieve heat transfer and reduce energy consumption.

[0049] In some embodiments, the mixed raw gas and the synthesis gas formed by the reduction reaction device are heat exchanged in the second heat exchange device, and the synthesis gas is cooled and then enters the cooling device for cooling, and then enters the solvent absorption device. The mixed raw gas is heated and then enters the reduction reaction device.

[0050] In some embodiments, the dust gas phase enters the dust collection device for dust removal, and part of the gas after dust removal passes through the particle lifting device as lifting gas, the lifting gas includes nitrogen, and enters the separation device through the lifting pipeline. The remaining gas enters the dust removal device for dust removal and then serves as the dust removal gas of the separation device.

[0051] In some embodiments, the mixed gas is first compressed by a crude hydrogen compression device before entering the hydrogen extraction device for hydrogen purification, which is more conducive to subsequent purification.

[0052] In some embodiments, the reduced oxygen carrier includes Fe oxide containing Ni and Al2O3, and the Fe oxide is Fe2O3 or FeO. In some embodiments, the reduced oxygen carrier is Fe2O3 / Al2O3 oxygen carrier containing Ni, which includes, by mass percentage, Fe2O3 35%, Ni 5% and Al2O3 60%. It should be noted that the reduced oxygen carrier can be an existing conventional oxygen carrier, or can be prepared by a conventional preparation method, as long as the above-mentioned suitable ratio of ferric oxide, nickel and aluminum oxide is satisfied.

[0053] In some embodiments, the lean solvent is countercurrently contacted with the synthesis gas in a solvent absorption device. In some embodiments, the lean solvent includes a physical solvent and a chemical solvent, the physical solvent has a greater solubility in carbon dioxide under pressure, and a lower solubility in carbon dioxide under normal pressure. The chemical solvent includes various amine solutions, such as MEA (ethanolamine), DEA (ethylenediamine) or MDEA (methyldiethanolamine) solutions, with a concentration (mass content) of 25% to 35% (e.g., 25%, 28%, 30%, 32%, etc.), which can react with carbon dioxide at room temperature to form ammonium carbonate or ammonium bicarbonate, and can be decomposed into amine solution and carbon dioxide after heating.

[0054] In some embodiments, the temperature of the air oxidation reaction is 650-800° C., such as 650° C., 670° C., 700° C., 720° C., 750° C., 780° C., 790° C., 800° C., etc., or any range therebetween. The pressure of the air oxidation reaction is from atmospheric pressure to 2.0 Mpag, such as 0.5 Mpag, 1 Mpag or 2.0 Mpag, etc.

[0055] In some embodiments, the temperature of the reduction reaction is 500-650°C, such as 500°C, 550°C, 600°C, 650°C, etc., and the pressure of the reduction reaction is from normal pressure to 2.0Mpag, such as 0.5Mpag, 1Mpag or 2.0Mpag, etc. The reduction reaction adopts a lower temperature, which is greatly reduced compared with the reaction temperature (850-950°C) of conventional process conditions.

[0056] In some embodiments, the mixed feed gas includes feed gas and water vapor, the feed gas includes methane or natural gas, and the water-to-carbon ratio of water vapor to feed gas is 1 to 3, such as 1, 1.5, 2, 2.5 or 3. By introducing water vapor into the reduction reactor, the reduction reaction temperature is lowered.

[0057] The following is further explained in conjunction with specific embodiments.

[0058] Example 1

[0059] A chemical chain hydrogen production system coupled with solvent absorption and capture of carbon dioxide, such as Figure 1 As shown, it includes an air oxidation reaction unit, a reduction reaction unit, a hydrogen extraction unit, a solvent absorption decarbonization unit and an oxygen carrier circulation feeding unit. The oxygen carrier circulation feeding unit includes a separation device 1, a dust collection device 2, a particle lifting device 3, a lifting pipe 4 and a dust removal device 5. The air oxidation reaction unit includes an air oxidation reaction device 6, a first heat exchange device 7, and a compressed air supply source. The reduction reaction unit includes a reduction reaction device 8, a second heat exchange device 9 and a mixed raw gas supply source. The solvent absorption decarbonization unit includes a cooling device 10, a solvent absorption device 11, a solvent regeneration device 12 and a reboiling device 13. The hydrogen extraction unit includes a crude hydrogen compression device 14 and a PSA hydrogen extraction device 15.

[0060] The air oxidation reaction device 6 is used to obtain oxidized oxygen carriers and hot oxygen-deficient air; the compressed air source is connected to the gas inlet of the air oxidation reaction unit through the first heat exchange device 7; the gas outlet of the air oxidation reaction device 6 is connected to the reboiler 13 through the first heat exchange device 7; the feed inlet of the air oxidation reaction device 6 is connected to the discharge port of the separation device 1.

[0061] The reduction reaction device 8 is used to mix the mixed raw gas with the oxidized oxygen carrier to obtain synthesis gas and reduced oxygen carrier; the mixed raw gas supply source is connected to the gas inlet of the reduction reaction device 8 through the second heat exchange device 9; the feed inlet of the reduction reaction device 8 is connected to the discharge port of the air oxidation reaction device 6; the discharge port is connected to the oxygen carrier circulation supply unit; the gas outlet of the reduction reaction device 8 is connected to the solvent absorption device 11 through the second heat exchange device 9 and the cooling device 10.

[0062] The solvent absorption device 11 is used to absorb carbon dioxide in the synthesis gas to obtain a mixed gas and a rich solvent, and the solvent regeneration device 12 is used to desorb carbon dioxide in the rich solvent and form a lean solvent; the cooling device 10 is used to cool the synthesis gas; and the reboiler 13 is connected to the solvent regeneration device 12. The gas outlet of the solvent absorption device 11 is connected to the feed inlet of the PSA hydrogen extraction device 15; the liquid outlet of the solvent absorption device 11 is connected to the feed inlet of the solvent regeneration device 12; the liquid inlet of the solvent absorption device 11 is connected to the lean solvent supply source through a pipeline; the solvent regeneration device 12 also includes a carbon dioxide outlet and a liquid phase outlet, and the liquid phase outlet is connected to the above-mentioned pipeline connected to the lean solvent supply source.

[0063] The PSA hydrogen extraction device 15 is used to purify hydrogen and obtain desorption gas; the PSA hydrogen extraction device 15 is provided with a hydrogen outlet and a desorption gas outlet; the desorption gas outlet is connected to the mixed raw gas supply source (specifically connected to the raw gas inlet pipeline); the gas outlet of the solvent absorption device 11 is connected to the PSA hydrogen extraction device 15 through the crude hydrogen compression device 14.

[0064] The oxygen carrier circulation feeding unit is used to provide reduced oxygen carriers for the air oxidation reaction device 6, and to realize the transportation and flow control of the reduced oxygen carriers from bottom to top. The particle lifting device 3 is connected to the first feed port of the separation device 1 through the lifting pipe 4; the first discharge port of the separation device 1 is connected to the feed port of the air oxidation reaction device 6; the second discharge port of the separation device 1 is connected to the feed port of the particle lifting device 3 and the feed port of the dust removal device 5 through the dust collection device 2, and the discharge port of the dust removal device 5 is connected to the second feed port of the separation device 1.

[0065] Example 2

[0066] A method for producing hydrogen by chemical chaining by coupling solvent absorption and capture of carbon dioxide, comprising the following steps:

[0067] The separation device 1 in the oxygen carrier circulation feeding unit provides a reduced oxygen carrier, which is a Fe2O3 / Al2O3 oxygen carrier containing Ni. Under the action of gravity, the reduced oxygen carrier slowly moves downward to the air oxidation reaction device 6 of the air oxidation reaction unit. The compressed air provided by the compressed air source enters the air oxidation reaction device 6 and undergoes an air oxidation reaction with the reduced oxygen carrier. The temperature of the air oxidation reaction is 750°C and the pressure is 1Mpag to form an oxidized oxygen carrier and hot oxygen-depleted air. The hot oxygen-depleted air exchanges heat with the compressed air source through the first heat exchange device 7, and then enters the reboiler 13 after cooling to provide heat to heat the mixed phase in the solvent regeneration device 12 to provide a heat source.

[0068] The oxidized oxygen carrier formed in the air oxidation reaction device 6 slowly moves downward to the reduction reaction device 8 of the reduction reaction unit under the action of gravity; the mixed raw gas is provided with a mixed raw gas, the mixed raw gas includes natural gas and water vapor, the water-to-carbon ratio of water vapor and natural gas is 2, and the mixed raw gas enters the reduction reaction device 8 after passing through the second heat exchange device 9, contacts with the oxidized oxygen carrier and undergoes a reduction reaction, the temperature of the reduction reaction is 600°C, and the pressure of the reduction reaction is from normal pressure to 1Mpag, generating a synthesis gas with a high hydrogen content and a reduced oxygen carrier.

[0069] The reduced oxygen carrier formed in the reduction reaction device 8 is lifted to the separation device 1 through the lifting pipe 4 under the action of the particle lifting device 3 for separation treatment to obtain the purified reduced oxygen carrier and the dust gas phase. The dust gas phase enters the dust collection device 2 for dust removal. Part of the gas after dust removal passes through the particle lifting device 3 as the lifting gas (nitrogen), and the remaining gas enters the dust removal device 5 for dust removal and then serves as the dust removal gas of the separation device 1.

[0070] The synthesis gas is cooled after passing through the second heat exchange device 9, and then enters the cooling device 10 to cool to room temperature, and then enters the solvent absorption device 11 of the solvent absorption decarbonization unit, and absorbs carbon dioxide after mixing with the lean solvent to obtain a mixed gas and a rich solvent. The lean solvent adopts a 30% MDEA aqueous solution. The mixed gas enters the PSA hydrogen extraction device 15 of the hydrogen extraction unit to purify the hydrogen to obtain high-purity hydrogen and desorbed gas. The desorbed gas includes methane, hydrogen, carbon monoxide and carbon dioxide. After the desorbed gas is mixed with the mixed raw gas, it flows back to the reduction reaction device 8 through the second heat exchange device. The rich solvent enters the solvent regeneration device 12 to desorb carbon dioxide to obtain high-concentration carbon dioxide and regenerated lean solvent. The regenerated lean solvent flows back to the solvent absorption device 11 for recycling.

[0071] Example 3

[0072] A chemical chain hydrogen production method for coupling solvent absorption and capture of carbon dioxide, which differs from Example 2 in that:

[0073] The water-to-carbon ratio of water vapor and methane is 2.5.

[0074] The temperature of the air oxidation reaction is 700°C and the pressure is 0.8Mpag;

[0075] The temperature of the reduction reaction is 550° C., and the pressure of the reduction reaction is from normal pressure to 0.8 Mpag.

[0076] Example 4

[0077] A chemical chain hydrogen production method for coupling solvent absorption and capture of carbon dioxide, which differs from Example 2 in that:

[0078] The water-to-carbon ratio of water vapor and methane is 2.

[0079] The temperature of the air oxidation reaction is 650°C and the pressure is 0.5Mpag;

[0080] The temperature of the reduction reaction is 500° C., and the pressure of the reduction reaction is from normal pressure to 0.5 MPag.

[0081] Example 5

[0082] A chemical chain hydrogen production method for coupling solvent absorption and capture of carbon dioxide, which differs from Example 2 in that:

[0083] The water-to-carbon ratio of water vapor and methane is 3.

[0084] The temperature of the air oxidation reaction is 800°C and the pressure is 2Mpag;

[0085] The temperature of the reduction reaction is 650° C., and the pressure of the reduction reaction is from normal pressure to 2 Mpag.

[0086] Experimental example

[0087] In the methods of Examples 2 to 5 of the present invention, the results of the raw material utilization rate, the carbon dioxide capture rate, and the hydrogen production rate per unit methane are shown in Table 1.

[0088] Table 1 Raw material utilization rate, carbon dioxide capture rate, and hydrogen production rate per unit of methane

[0089]

[0090] As can be seen from the above, the method of the present invention can achieve 100% conversion of raw materials, the capture rate of carbon dioxide is 100%, and the purity is not less than 98%; it can achieve self-heating balance, and the reduction reaction adopts a lower temperature, which is much lower than the reaction temperature under conventional process conditions; it can reduce energy consumption and cost, and the hydrogen production rate per unit of methane can reach 2.6Nm 3 / Nm 3 The traditional steam reforming process and the conventional chemical chain hydrogen production process are usually 2.2-2.4Nm 3 / Nm 3 Methane.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chemical chain hydrogen production system for coupling solvent absorption and capture of carbon dioxide, characterized in that: It includes an air oxidation reaction unit, a reduction reaction unit, a hydrogen extraction unit, a solvent absorption decarbonization unit and an oxygen carrier circulation feeding unit; The air oxidation reaction unit comprises an air oxidation reaction device, and the air oxidation reaction device is used to obtain oxidized oxygen carriers and hot oxygen-deficient air; The reduction reaction unit comprises a reduction reaction device, and the reduction reaction device is used to mix the mixed raw gas with the oxidized oxygen carrier to obtain synthesis gas and reduced oxygen carrier; The solvent absorption decarbonization unit comprises a solvent absorption device and a solvent regeneration device, wherein the solvent absorption device is used to absorb carbon dioxide in the synthesis gas to obtain a mixed gas and a rich solvent, and the solvent regeneration device is used to desorb carbon dioxide in the rich solvent and form a lean solvent; The hydrogen extraction unit includes a hydrogen extraction device, and the hydrogen extraction device is used to purify hydrogen and obtain desorbed gas; The oxygen carrier circulation supply unit is used to provide the air oxidation reaction device with reduced oxygen carriers, and to realize the transportation and flow control of the reduced oxygen carriers from bottom to top.

2. The chemical chain hydrogen production system for capturing carbon dioxide by coupling solvent absorption according to claim 1 is characterized in that: The oxygen carrier circulation feeding unit includes a separation device, a dust removal device, a dust collection device, a lifting pipe and a particle lifting device; The particle lifting device is connected to the first feed port of the separation device through the lifting pipe; the first discharge port of the separation device is connected to the feed port of the air oxidation reaction device; the second discharge port of the separation device is respectively connected to the feed port of the particle lifting device and the feed port of the dust removal device through the dust collection device, and the discharge port of the dust removal device is connected to the second feed port of the separation device.

3. The chemical chain hydrogen production system for capturing carbon dioxide by coupling solvent absorption according to claim 2 is characterized in that: The solvent absorption decarbonization unit further comprises a cooling device and a reboiling device; the cooling device is used to cool the synthesis gas; the reboiling device is connected to the solvent regeneration device; The gas outlet of the solvent absorption device is connected to the feed inlet of the hydrogen extraction device; the liquid outlet of the solvent absorption device is connected to the feed inlet of the solvent regeneration device; the liquid inlet of the solvent absorption device is connected to the lean solvent supply source; The solvent regeneration device further comprises a carbon dioxide outlet and a liquid phase outlet, wherein the liquid phase outlet is connected to the lean solvent supply source or the liquid inlet of the solvent absorption device.

4. The chemical chain hydrogen production system for capturing carbon dioxide by coupling solvent absorption according to claim 3 is characterized in that: The air oxidation reaction unit further comprises a first heat exchange device and a compressed air source, wherein the compressed air source is connected to a gas inlet of the air oxidation reaction unit through the first heat exchange device; The gas outlet of the air oxidation reaction device is connected to the reboiler through the first heat exchange device; the feed inlet of the air oxidation reaction device is connected to the discharge outlet of the separation device.

5. The chemical chain hydrogen production system for capturing carbon dioxide by coupling solvent absorption according to claim 4 is characterized in that: The reduction reaction unit further comprises a second heat exchange device and a mixed raw gas supply source, wherein the mixed raw gas supply source is connected to the gas inlet of the reduction reaction device through the second heat exchange device; The feed inlet of the reduction reaction device is connected to the discharge port of the air oxidation reaction device; the discharge port of the reduction reaction device is connected to the riser of the oxygen carrier circulation feeding unit; the gas outlet of the reduction reaction device is connected to the solvent absorption device through the second heat exchange device and the cooling device.

6. The chemical chain hydrogen production system for capturing carbon dioxide by coupling solvent absorption according to claim 1 is characterized in that: The hydrogen extraction device comprises a PSA hydrogen extraction device, and the hydrogen extraction device is provided with a hydrogen outlet and a desorption gas outlet; the desorption gas outlet is connected to a mixed raw material gas supply source; The hydrogen extraction unit further comprises a crude hydrogen compression device, and the gas outlet of the solvent absorption device is connected to the hydrogen extraction device through the crude hydrogen compression device.

7. A chemical chain hydrogen production method for coupling solvent absorption and capture of carbon dioxide, characterized in that: The chemical chain hydrogen production system using a coupled solvent to absorb and capture carbon dioxide according to any one of claims 1 to 6 comprises the following steps: The separation device in the oxygen carrier circulation feeding unit provides the reduced oxygen carrier to the air oxidation reaction device of the air oxidation reaction unit to perform air oxidation reaction with the compressed air to form the oxidized oxygen carrier and hot oxygen-deficient air; The oxidized oxygen carrier enters the reduction reaction device of the reduction reaction unit and undergoes a reduction reaction with the mixed raw gas to form synthesis gas and a reduced oxygen carrier; The reduced oxygen carrier formed in the reduction reaction device is lifted to the separation device through a lifting pipe under the action of the particle lifting device for separation treatment to obtain purified reduced oxygen carrier and dust gas phase; The synthesis gas enters the solvent absorption device of the solvent absorption decarbonization unit, is mixed with the lean solvent and then absorbs carbon dioxide to obtain a mixed gas and a rich solvent; The mixed gas enters the hydrogen extraction device of the hydrogen extraction unit to purify the hydrogen to obtain high-purity hydrogen and desorbed gas, and the desorbed gas flows back to the reduction reaction device; The rich solvent enters the solvent regeneration device to desorb carbon dioxide to obtain high-concentration carbon dioxide and regenerated lean solvent, and the regenerated lean solvent flows back to the solvent absorption device.

8. The chemical chain hydrogen production method of coupling solvent absorption and capture of carbon dioxide according to claim 7 is characterized in that: Contains at least one of the following features (1) to (4): (1) The hot oxygen-depleted air and the compressed air provided by the compressed air source are heat exchanged through a first heat exchange device, and the compressed air is heated and enters the air oxidation reaction device, and the hot oxygen-depleted air is cooled and enters the reboiler to provide heat to heat the liquid phase in the solvent regeneration device; (2) The mixed raw gas and the synthesis gas formed by the reduction reaction device are heat exchanged in a second heat exchange device, and the synthesis gas is cooled and then enters the cooling device for cooling, and then enters the solvent absorption device, and the mixed raw gas is heated and then enters the reduction reaction device; (3) The dust gas phase enters the dust collection device for dust removal, and part of the gas after dust removal passes through the particle lifting device as lifting gas, and the remaining gas enters the dust removal device for dust removal and then serves as dust removal gas for the separation device; (4) Before the mixed gas enters the hydrogen extraction device for hydrogen purification, it is first compressed by the crude hydrogen compression device.

9. The chemical chain hydrogen production method of coupling solvent absorption and capture of carbon dioxide according to claim 7, characterized in that: Contains at least one of the following features (1) to (3): (1) The temperature of the air oxidation reaction is 650-800° C., and the pressure of the air oxidation reaction is normal pressure to 2.0 MPag; (2) The temperature of the reduction reaction is 500-650° C., and the pressure of the reduction reaction is normal pressure to 2.0 MPag; (3) The mixed raw gas includes raw gas and water vapor, the raw gas includes methane or natural gas, and the water-to-carbon ratio of water vapor to raw gas is 1 to 3.

10. The chemical chain hydrogen production method of coupling solvent absorption and capture of carbon dioxide according to claim 9, characterized in that: Contains at least one of the following features (1) to (2): (1) The capture rate of carbon dioxide is 100%; the concentration of the high-concentration carbon dioxide is greater than 98%; (2) The hydrogen production rate per unit of methane is 2.6 Nm 3 / Nm 3 More than methane.

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