Two-section absorption enhanced moving bed reactor

Abstract

The invention provides a two-section absorption-enhanced moving bed reactor, which relates to the technical field of hydrogen production, and comprises an upper half-section reduction reaction region and a lower half-section absorption-enhanced reaction region, the reduction reaction area is communicated with the absorption enhancement reaction area through a reducing section, an air inlet is formed in the lower end side wall of the reduction reaction area, and an exhaust pipe and a feeding pipe are arranged on the upper end side wall; an exhaust pipe and a feed pipe are arranged on the side wall of the upper end of the absorption-enhanced reaction region, and a solid material discharge hole is formed in the bottom of the absorption-enhanced reaction region; an exhaust pipe of the reduction reaction region is communicated with a reaction gas inlet of the absorption enhancement reaction region; a material inlet of the absorbent regeneration reactor is communicated with a material outlet of the absorption enhancement reaction region, a material outlet of the absorbent regeneration reactor is communicated with a feeding pipe of the absorption enhancement reaction region, and the absorbent regeneration reactor is used for conveying an absorbent into the absorption enhancement reaction region again. According to the invention, the hydrogen production reaction temperature is reduced, the purity of the hydrogen product is improved, and the self-heat balance of the reactor and the source separation and capture of CO2 are realized.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production from fossil energy, and in particular to a two-stage absorption-enhanced moving bed reactor. Background Art

[0002] As an emerging renewable energy source, hydrogen energy can effectively reduce carbon dioxide emissions and achieve efficient use of energy. How to produce hydrogen efficiently and sustainably is a very worthy issue to study. The existing hydrogen production process of steam methane reforming reaction has a complex catalytic process, and the pressure swing adsorption separation of carbon dioxide consumes a lot of energy. Water-based chemical chaining hydrogen production is an emerging hydrogen production method. In the process of oxygen carrier reduction reaction, hydrocarbon fuel is reduced to oxygen carrier under the action of water vapor to prepare H2, and reduced oxygen carrier and CO2 are obtained at the same time, so as to achieve low-energy separation of carbon dioxide in the hydrogen production process. The purity of hydrogen and the carbon dioxide capture rate can be further improved by introducing carbon dioxide absorbent, but its CO2 absorption performance is greatly affected by temperature, which makes it difficult to take into account the optimal temperature of the absorption reaction and the optimal temperature of the thermochemical reaction of hydrocarbon fuel. For the practical application of chemical chaining absorption intensification reaction, fixed bed, moving bed and fluidized bed are usually used to achieve it.

[0003] Compared with fixed bed reactors, moving bed reactors have better continuity and much less wear on internal oxygen carriers than fluidized bed reactors. Therefore, moving bed reactors are better matched with chemical looping hydrogen production processes. An existing moving bed continuous catalytic adsorption enhanced chemical looping reforming hydrogen production process uses glycerol, a byproduct of biodiesel, as a hydrogen production raw material. The system fully utilizes the redox oxygen transfer performance of NiO / Al2O3 oxygen carriers, uses CaO as an absorbent to enhance in-situ adsorption of hydrogen production CO2, and uses water vapor as the carrier gas of the reformer to separate the product water vapor and hydrogen, which can continuously and stably produce high-concentration hydrogen. However, in this process, the reduction reaction of the oxygen carrier and the absorption reaction of the absorbent occur simultaneously in the same reaction domain. However, higher temperatures are conducive to the reduction reaction of the oxygen carrier, but not to the absorption reaction of CO2. Since it is difficult to take into account the optimal reaction temperatures of both, the hydrogen production and decarbonization performance cannot achieve the overall efficiency maximization. In addition, the mismatch of the optimal working temperatures of the two makes the overall reaction control difficult and the side reactions proceed at a high level. The CO2 absorption enhancement cannot promote the reaction, and the product purity still has room for improvement. Other processes are still needed to further improve the CO2 capture rate, which brings about additional higher carbon dioxide capture energy consumption, thereby reducing the energy utilization efficiency of the system. How to further improve the technical and economic efficiency of the chemical chain system has become an urgent problem that the majority of chemical chain hydrogen production research technicians need to solve. Summary of the invention

[0004] In view of this, the embodiments of the present application provide a two-stage absorption-enhanced moving bed reactor and its application, so as to achieve the purposes of reducing system energy consumption, improving hydrogen purity and carbon dioxide utilization rate, etc.

[0005] The embodiment of the present application provides the following technical solution: a two-stage absorption-enhanced moving bed reactor, comprising: a reduction reaction zone in the upper half and an absorption-enhanced reaction zone in the lower half;

[0006] The reduction reaction domain and the absorption enhancement reaction domain are connected via a reduced diameter section, and solid particles are filled in the reaction domain and move downward by gravity; a reaction gas inlet for introducing hydrocarbon fuel is arranged on the lower side wall of the reduction reaction domain, and an exhaust pipe and a feed pipe for introducing solid materials are arranged on the upper side wall of the reduction reaction domain;

[0007] The lower side wall of the absorption enhancement reaction domain is provided with a reaction gas inlet, the upper side wall of the absorption enhancement reaction domain is provided with an exhaust pipe and a feed pipe for feeding a carbon dioxide absorbent, and the bottom of the absorption enhancement reaction domain is provided with a solid material discharge port; wherein the exhaust pipe of the reduction reaction domain is connected to the reaction gas inlet of the absorption enhancement reaction domain;

[0008] It also includes an absorbent regeneration reactor, the material inlet of the absorbent regeneration reactor is connected with the solid material discharge port of the absorption enhancement reaction domain, and the material outlet of the absorbent regeneration reactor is connected with the feed pipe of the absorption enhancement reaction domain, so as to allow the absorbent after absorbing carbon dioxide to enter the absorbent regeneration reactor for desorption and then be re-transported to the absorption enhancement reaction domain.

[0009] According to one embodiment of the present application, it also includes a mechanical lifting device, which is arranged between the connecting pipeline between the absorption enhancement reaction zone and the absorbent regeneration reactor, and is used to mechanically lift the absorbent after absorbing carbon dioxide and send it into the absorbent regeneration reactor.

[0010] According to one embodiment of the present application, a filter is further included, wherein the filter is arranged at the solid material discharge port at the bottom of the absorption enhancement reaction domain and is used to filter the solid powder in the gas product.

[0011] According to one embodiment of the present application, a filter, a condenser and a gas separator are sequentially arranged at the exhaust pipe on the upper side wall of the absorption enhancement reaction domain, so that the gas products generated by the reaction are collected after filtering, condensing and separating.

[0012] According to one embodiment of the present application, the solid material added to the feed pipe on the upper side wall of the reduction reaction zone is a hydrocarbon fuel reforming reaction catalyst or an oxygen carrier.

[0013] The two-stage absorption-enhanced moving bed reactor is in the form of a moving bed, and the hydrocarbon fuel reforming reaction catalyst or oxygen carrier and carbon dioxide absorbent flowing through the reactor flow downward by gravity.

[0014] According to one embodiment of the present application, a cut-off gas inlet is provided at the reduced diameter section for introducing cut-off gas to prevent gas cross-talk between the reduction reaction domain and the absorption enhancement domain.

[0015] According to one embodiment of the present application, it also includes an oxidation reactor and an air reactor, the feed inlet of the oxidation reactor is connected with the solid material discharge port of the absorption enhancement reaction domain, water vapor is introduced into the oxidation reactor to cause an oxidation reaction between the water vapor and the reduced oxygen carrier, the discharge port of the oxidation reactor is connected with the feed inlet of the air reactor, and is used to completely oxidize the partially oxidized oxygen carrier into an oxidized oxygen carrier, and the discharge port of the air reactor is connected with the feed pipe of the upper end side wall of the reduction reaction domain, and is used to send the completely oxidized oxygen carrier into the reduction reaction domain to re-participate in the reaction.

[0016] According to one embodiment of the present application, it also includes a screening device, which is arranged at the solid material discharge port of the absorption enhancement reaction domain, the first outlet of the screening device is connected to the feed port of the oxidation reactor, and the second outlet of the screening device is connected to the material inlet of the absorbent regeneration reactor, for separating the reduced oxygen carrier output from the absorption enhancement reaction domain and the absorbent after absorbing carbon dioxide, and sending them to the oxidation reactor and the absorbent regeneration reactor respectively.

[0017] According to one embodiment of the present application, it also includes a gas-solid separator, which is arranged between the connecting pipeline between the air reactor and the reduction reaction domain, and is used to perform gas-solid separation on the completely oxidized oxygen carrier, and send the separated oxygen carrier into the reduction reaction domain to participate in the reaction again.

[0018] According to one embodiment of the present application, the main component of the carbon dioxide absorbent in the absorption enhancement reaction domain is Li4SiO4 or Li2ZrO3 or CaO, etc.

[0019] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0020] 1. The reactor used in the embodiment of the present invention is a moving bed reactor, which has fast reaction kinetics and good heat transfer characteristics compared with the traditional fixed bed reactor, prevents the back mixing of solids and gases in the reactor, and reduces the energy loss of the system.

[0021] 2. Compared with the ordinary single-stage co-current / countercurrent moving bed, the two-stage reduction reactor described in the embodiment of the present invention divides the reactor into two reaction domains. The absorption reaction of the absorbent and the oxidation reaction of the reduced oxygen carrier can be carried out step by step, so that the bed temperature is better matched with the target reaction, and the reaction performance of the CO2 absorbent and the reduction reaction performance of the oxygen carrier are fully utilized.

[0022] 3. The absorption reaction of the absorbent described in the embodiment of the present invention can be carried out at a relatively low temperature. The absorbent can absorb carbon dioxide at about 550°C, with good absorption effect, high purity of product hydrogen, and reduced heat load of the reactor.

[0023] 4. The reactor described in the embodiment of the present invention can be used for both methane absorption enhanced reforming reaction and natural gas chemical chain hydrogen production reaction, and has a wide range of applications.

[0024] 5. In the embodiment of the present invention, during the reaction process in the absorption enhancement reaction domain, the saturated absorbent at its outlet enters the absorbent regeneration reactor for regeneration and can be sent to the absorption enhancement reaction domain for reuse by gas transportation. It can quickly absorb carbon dioxide in the mixed gas without stopping the machine to replace the absorbent, and has good continuity and production efficiency.

[0025] 6. While producing high-purity hydrogen, the reactor can capture carbon dioxide at the source and can be organically coupled with other devices to achieve efficient utilization of carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 2 is a schematic structural diagram of a two-stage absorption enhanced moving bed reactor according to an embodiment of the present invention;

[0028] Figure 2 This is a process diagram of a methane absorption-enhanced reforming reaction system based on a two-stage absorption-enhanced moving bed reactor in an embodiment of the present invention;

[0029] Figure 3 This is a process diagram of a natural gas water-based chemical chain hydrogen production system based on a two-stage absorption-enhanced moving bed reactor in an embodiment of the present invention;

[0030] Among them, 1-reduction reaction domain, 2-absorption enhancement reaction domain, 3-partition gas inlet, 4-second electric slide valve, 5-reaction gas inlet of the reduction reaction domain, 6-reaction gas inlet of the absorption enhancement reaction domain, 7-exhaust pipe of the reduction reaction domain, 8-feed pipe of the reduction reaction domain, 9-feed pipe of the absorption enhancement reaction domain, 10-exhaust pipe of the absorption enhancement reaction domain. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0032] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0033] like Figure 1 As shown, an embodiment of the present invention provides a two-stage absorption-enhanced moving bed reactor, comprising: a reduction reaction domain 1 in the upper half and an absorption-enhanced reaction domain 2 in the lower half;

[0034] The reduction reaction domain 1 and the absorption enhancement reaction domain 2 are connected to each other through a reduced diameter section, the lower side wall of the reduction reaction domain 1 is provided with a reaction gas inlet 5 for introducing hydrocarbon fuel, and the upper side wall of the reduction reaction domain 1 is provided with an exhaust pipe and a feed pipe for adding solid materials;

[0035] The lower side wall of the absorption enhancement reaction domain 2 is provided with a reaction gas inlet, the upper side wall of the absorption enhancement reaction domain 2 is provided with an exhaust pipe and a feed pipe for adding a carbon dioxide absorbent, and the bottom of the absorption enhancement reaction domain 2 is provided with a solid material discharge port; wherein the exhaust pipe 7 of the reduction reaction domain is connected to the reaction gas inlet 6 of the absorption enhancement reaction domain;

[0036] It also includes an absorbent regeneration reactor, the material inlet of the absorbent regeneration reactor is connected to the solid material discharge port of the absorption enhancement reaction domain 2, and the material outlet of the absorbent regeneration reactor is connected to the feed pipe 9 of the absorption enhancement reaction domain, so as to allow the absorbent after absorbing carbon dioxide to enter the absorbent regeneration reactor for desorption and then be re-transported to the absorption enhancement reaction domain 2.

[0037] A two-stage absorption-enhanced moving bed reactor of this embodiment can be used for methane absorption-enhanced reforming reaction, and can also be used for natural gas chemical chain hydrogen production reaction. Among them, the reduction reaction domain 1 and the absorption-enhanced reaction domain 2 are connected through a reduced diameter section, solid particles are filled in the reaction domain, and move downward by gravity; the solid material discharge port of the absorption-enhanced reaction domain 2 is also provided with a second electric slide valve 4 to control the material flow rate. The reaction gas inlet 5 of the reduction reaction domain is used to introduce reaction gases, such as methane and water vapor. The feed pipe 8 of the reduction reaction domain is used to add material such as catalysts or oxygen carriers, and the exhaust pipe 10 of the absorption-enhanced reaction domain is used to discharge prepared gases, such as hydrogen and carbon monoxide.

[0038] In a specific implementation of this embodiment, it also includes a mechanical lifting device, which is arranged between the connecting pipeline between the absorption enhancement reaction zone and the absorbent regeneration reactor, and is used to mechanically lift the absorbent after absorbing carbon dioxide and send it into the absorbent regeneration reactor.

[0039] In order to prevent the countercurrent flow between the solid particles and the gas, which may cause the solid particles to be pulverized or broken, a specific implementation of this embodiment also includes a filter, which is arranged at the solid material discharge port at the bottom of the absorption enhancement reaction domain, and is used to filter the solid powder in the gas product.

[0040] In a specific implementation of this embodiment, a filter, a condenser and a gas separator are sequentially arranged at the exhaust pipe on the upper side wall of the absorption enhancement reaction domain, so that the gas products generated by the reaction are collected after filtering, condensing and separating.

[0041] In the specific implementation of this embodiment, the two-stage reduction reactor used in this embodiment includes two reaction domains, the upper part of the reactor is the upper half reaction domain, and the lower part of the reactor is the lower half reaction domain. The two reaction domains are connected by a shrinking section, and the lower end side of the upper half reaction domain is provided with an air inlet, and the upper end side is provided with a feed pipe and an exhaust pipe for adding solid materials; the lower end side of the lower half reaction domain is provided with an air inlet, and the upper end side is provided with a solid material feed pipe and an exhaust pipe, and the bottom is provided with a solid discharge port. After the solid material exiting from the bottom end of the lower half reaction domain is sieved and separated, it can re-enter the reactor through the solid material feed pipe provided in the lower half reaction domain and the upper end side of the upper half reaction domain. The gas discharged from the exhaust pipe on the upper end side of the upper half reaction domain is collected and utilized after passing through a filter, a heat exchanger and a condenser in sequence.

[0042] In the upper reaction zone, chemical reactions of methane, water vapor and solid materials occur, and methane and water vapor enter the system from the lower side of the upper reaction zone of the moving bed. High-temperature solid materials flow downward evenly from the top, in the opposite direction of the flow of reactant / product gases, and the generated gas re-enters the system from the lower side inlet of the lower reaction zone, while the solids flow downward into the lower reaction zone by gravity.

[0043] In the lower half of the reaction zone, an absorption reaction of the absorbent occurs, and the gas entering from the lower end side of the lower half of the reaction zone contacts and reacts fully with the absorbent entering from the upper end side and the solid material entering from the top in countercurrent to obtain higher purity hydrogen, which is discharged from the top and passes through the filter, heat exchanger and condenser in sequence to finally obtain high purity hydrogen. At the same time, the solid material is discharged from the bottom of the lower half of the reaction zone.

[0044] The saturated absorbent from the bottom outlet of the lower half reaction zone enters the absorbent regeneration reactor for regeneration, and then enters the lower half reaction zone again through the absorbent feed pipe at the upper side of the lower half reaction zone, thus realizing the cyclic regeneration of the absorbent.

[0045] When the two-stage reactor of this embodiment is used for methane absorption enhanced reforming reaction, the solid material added to the feed pipe on the upper side wall of the reduction reaction zone is a hydrocarbon fuel reforming reaction catalyst.

[0046] When the two-stage reactor described in this embodiment is used for the natural gas chemical chain hydrogen production reaction, the solid material added to the feed pipe on the upper side wall of the reduction reaction zone is an oxygen carrier.

[0047] In the present embodiment, a cut-off gas inlet 3 is provided at the reduced diameter section for introducing cut-off gas to prevent gas cross-talk between the reduction reaction domain and the absorption enhancement domain.

[0048] When used for the natural gas chemical chain hydrogen production reaction, in a specific implementation of this embodiment, it also includes an oxidation reactor and an air reactor, the feed inlet of the oxidation reactor is connected with the solid material discharge port of the absorption enhancement reaction domain, water vapor is introduced into the oxidation reactor to cause an oxidation reaction between the water vapor and the reduced oxygen carrier, the discharge port of the oxidation reactor is connected with the feed inlet of the air reactor, and is used to completely oxidize the partially oxidized oxygen carrier into an oxidized oxygen carrier, and the discharge port of the air reactor is connected with the feed pipe of the upper end side wall of the reduction reaction domain, and is used to send the completely oxidized oxygen carrier into the reduction reaction domain to re-participate in the reaction.

[0049] In a specific implementation of this embodiment, it also includes a screening device, which is arranged at the solid material discharge port of the absorption enhancement reaction domain, the first outlet of the screening device is connected to the feed port of the oxidation reactor, and the second outlet of the screening device is connected to the material inlet of the absorbent regeneration reactor, which is used to separate the reduced oxygen carrier output from the absorption enhancement reaction domain and the absorbent after absorbing carbon dioxide, and send them to the oxidation reactor and the absorbent regeneration reactor respectively.

[0050] In a specific implementation of this embodiment, it also includes a gas-solid separator, which is arranged between the connecting pipeline between the air reactor and the reduction reaction domain, and is used to perform gas-solid separation on the completely oxidized oxygen carrier, and send the separated oxygen carrier into the reduction reaction domain to participate in the reaction again.

[0051] The entire reactor of the embodiment of the present invention is self-heating balanced and does not need to be heated by the outer wall; the heat demand of the reaction is met by the sensible heat of the solid particles themselves in the reduction reaction domain; in the absorption enhancement reaction domain, the heat released by the CO2 absorption process meets the heat absorption demand of the reduction reaction / reforming reaction. The reactor of the embodiment of the present invention is in the form of a moving bed, and the solid particles are filled in the reactor and move downward by gravity.

[0052] The two-stage reactor described in the embodiment of the present invention can be used for methane absorption enhanced reforming reaction, and can also be used for natural gas chemical chain hydrogen production reaction. The reactor is further described below in conjunction with the accompanying drawings and specific embodiments.

[0053] Example 1: The two-stage reactor of this example is used for methane absorption-enhanced reforming reaction. In the reduction reaction zone, solid particles enter at about 800°C, and are reduced to 600°C through the reduction reaction zone; then they enter the absorption-enhanced reaction zone, mix with the absorbent, and undergo absorption-enhanced reaction at a temperature of 550-600°C. The solid material added to the feed pipe on the upper side wall of the reduction reaction zone is a hydrocarbon fuel reforming reaction catalyst.

[0054] This embodiment proposes a methane absorption enhanced reforming reaction system based on a two-stage reactor. The system flow chart is as follows: Figure 2 As shown. The system mainly includes a two-stage reduction reactor (including the lower half reaction zone and the upper half reaction zone), an absorbent regeneration reactor, and a mechanical riser. Based on the two-stage reduction reactor, the system can achieve zero-energy consumption of carbon dioxide and high-purity synthesis gas production.

[0055] The internal temperature of the upper reaction zone described in this embodiment is 600-800°C. The methane raw material is flow-controlled by a gas mass flowmeter, and then enters the lower end side of the upper reaction zone together with the water raw material after being preheated in the vaporizer. The gas material contacts the nickel-based catalyst to undergo a reforming reaction to generate CO, H2 and a small amount of CO2. The gas generated by the reforming reaction re-enters the system from the lower end side of the lower reaction zone through the air inlet pipe.

[0056] The internal temperature of the lower half reaction zone described in this embodiment is 500-700°C; the output gas of the upper half reaction zone enters from the lower end side of the lower half reaction zone, and flows upward to countercurrently contact with the carbon dioxide absorbent Li4SiO4 or Li2ZrO3 to undergo absorption reaction. After the reaction is completed, the gas product is discharged from the upper end side exhaust port of the lower half reaction zone. At the same time, the saturated absorbent is controlled by the flow rate of the electric slide valve and then lifted by the mechanical lifting pipe to enter the absorbent regeneration reactor. After sufficient reaction, it can re-enter the system reaction, thereby realizing the circulation of the absorbent.

[0057] The internal temperature of the absorbent regeneration reactor described in this embodiment is 600-750°C; the saturated absorbent from the bottom outlet of the lower half reaction domain is mechanically lifted and enters the absorbent regeneration reactor for regeneration, and then enters the lower half reaction domain again from the absorbent feeding port on the upper side of the lower half reaction domain, thereby realizing the cyclic regeneration of the absorbent. The fresh absorbent has good absorption performance and improves the carbon dioxide absorption efficiency.

[0058] Due to the countercurrent flow between solid particles and gas, solid particles may be pulverized or broken. In order to prevent the powdered materials produced by the pulverization or crushing of solid materials from clogging the reaction gas pipeline, a filter needs to be set at the outlet of the lower half of the reaction domain to filter the solid powder in the gas product. After the product gas is discharged from the top of the absorption enhancement reactor, it passes through the filter tank to filter the solid oxygen carrier and absorbent powder that may be mixed in the gas product. The filtered gas product enters the heat exchanger (condenser) for cooling, and then enters the gas-liquid separation tank for gas-liquid separation. The condensed gas enters the tail gas protection tank after adjusting the reaction pressure through the pressure control valve, and then enters the wet flow meter for volume flow measurement.

[0059] The specific steps of implementing the methane absorption enhanced reforming reaction system based on the two-stage reactor described above are as follows:

[0060] Methane and water are preheated and mixed in a mixer before entering from the lower side of the upper reaction zone. The gaseous material contacts the nickel-based catalyst to undergo a reforming reaction to generate CO, H2 and a small amount of CO2. The gas generated by the reforming reaction re-enters the system from the lower side of the lower reaction zone through the intake pipe, and flows upward to countercurrently contact with the carbon dioxide absorbent Li4SiO4 or Li2ZrO3 to undergo an absorption reaction. After the reaction, the gaseous product is discharged from the upper side exhaust pipe of the lower reaction zone, and is separated by a filter, a condenser and a gas separator. The condensed gas is collected in the tail gas protection tank after the reaction pressure is adjusted by a pressure control valve. At the same time, the saturated absorbent is controlled by an electric slide valve and then lifted by a mechanical lifting pipe. After entering the absorbent regeneration reactor for regeneration, it enters from the solid feed pipe on the upper side of the lower reaction zone, thus completing a methane absorption enhanced reforming reaction cycle.

[0061] Embodiment 2: The two-stage reactor of this embodiment is used for the natural gas chemical chain hydrogen production reaction, and the solid material added to the feed pipe on the upper side wall of the reduction reaction zone is an oxygen carrier.

[0062] This embodiment proposes a natural gas water-based chemical chain hydrogen production system based on a two-stage reactor. The system flow chart is as follows: Figure 3 As shown. The system mainly includes: a two-stage reduction reactor (including the lower half reaction domain and the upper half reaction domain), an oxidation reactor, an air reactor, an absorbent regeneration reactor, and a screening. The system uses natural gas, water, and air as raw materials. The system is equipped with a natural gas feed pipeline, two water working fluid feed pipelines, an air feed pipeline, a carbon dioxide absorbent feed pipeline, a high-temperature oxygen carrier feed pipeline, and a product gas outlet pipeline. Based on the two-stage reduction reactor, the system can achieve zero-energy separation of carbon dioxide and production of high-purity hydrogen.

[0063] The internal temperature of the upper half reaction domain described in this embodiment is 550-750°C; the methane raw material is flow-controlled by a gas mass flowmeter, and then enters the lower end side of the upper half reaction domain together with the water raw material after being preheated in the vaporizer, and the gas material flows from bottom to top and contacts with the oxygen carrier Fe2O3 in countercurrent to produce a thermochemical reaction to generate FeO, H2 and a small amount of CO2, and the gas generated by the thermochemical reaction re-enters the system from the lower end side of the lower half reaction domain through the air inlet pipe, and at the same time, the reduced oxygen carrier FeO moves downward, and enters the lower half reaction domain at the lower position after the flow is controlled by the electric slide valve;

[0064] The internal temperature of the lower half reaction zone described in this embodiment is 500-650°C; the output gas of the upper half reaction zone enters from the lower end side of the lower half reaction zone, and flows upward to countercurrently contact with the carbon dioxide absorbent Li4SiO4 or Li2ZrO3 and the reduced oxygen carrier FeO to produce an absorption enhancement reaction. After the reaction is completed, the gas product is discharged from the upper end side exhaust port of the lower half reaction zone. At the same time, the reduced oxygen carrier and the saturated absorbent are separated by entering the bottom screening after the flow rate is controlled by the electric slide valve, and then enter the oxidation reactor and the absorbent regeneration reactor respectively. After sufficient reaction, they can re-enter the system reaction, thereby realizing the overall circulation of solid materials.

[0065] The internal temperature of the oxidation reactor described in this embodiment is 550-650°C; the reduced oxygen carrier discharged from the bottom of the lower half of the reaction zone flows into the oxidation reactor from the feed port at the upper end of the oxidation reactor, and undergoes an oxidation reaction with the water vapor entering the reactor from the side of the lower end of the oxidation reactor after preheating. The reduced oxygen carrier FeO is oxidized by the water vapor in the oxidation reactor to a high-valent reduced oxygen carrier Fe3O4, and then lifted by the air into the air reactor.

[0066] The internal temperature of the air reactor described in this embodiment is 600-800°C; the outlet of the air reactor is connected to the gas-solid separator, and the solid outlet of the separator is connected to the top of the upper reaction domain. While the oxygen carrier is lifted in the gas lift pipe, it is oxidized by the air to become an oxidized oxygen carrier Fe2O3, and after separation by the gas-solid separator, it re-enters the top of the upper reaction domain. While replenishing the oxygen carrier, it also supplies a part of the heat required for the reaction in the upper reaction domain, thereby realizing efficient utilization of heat.

[0067] The internal temperature of the absorbent regeneration reactor described in this embodiment is about 650°C; the saturated absorbent from the bottom outlet of the lower half reaction domain is mechanically lifted into the absorbent regeneration reactor for regeneration, and then enters the lower half reaction domain again through the absorbent feed pipe on the upper side of the upper half reaction domain, thereby realizing the cyclic regeneration of the absorbent. The fresh absorbent has good absorption performance and improves the carbon dioxide absorption efficiency.

[0068] Due to the countercurrent flow between solid particles and gas, solid particles may be pulverized or broken. In order to prevent the powdered materials produced by the pulverization or crushing of solid materials from clogging the reaction gas pipeline, a filter needs to be set at the outlet of the lower half of the reaction domain to filter the solid powder in the gas product. After the product gas is discharged from the top of the absorption enhancement reactor, it passes through the filter tank to filter the solid oxygen carrier and absorbent powder that may be mixed in the gas product. The filtered gas product enters the heat exchanger (condenser) for cooling, and then enters the gas-liquid separation tank for gas-liquid separation. The non-condensable gas enters the tail gas protection tank after the reaction pressure is adjusted by the pressure control valve, and then enters the wet flow meter for volume flow measurement.

[0069] The specific steps of implementing the natural gas water-based chemical chain hydrogen production system based on the two-stage reactor described above are as follows:

[0070] After being preheated and mixed in a mixer, methane and water enter from the lower side of the upper reaction domain, countercurrently contact with the oxygen carrier entering from the top to produce a thermochemical reaction to generate ferrous oxide, hydrogen and a small amount of carbon dioxide. The generated gas products are discharged through an exhaust pipe, and enter from the intake pipe at the lower side of the lower reaction domain and flow upward. The reduced oxygen carrier is controlled by an electric slide valve to enter from the top of the lower reaction domain. At the same time, the absorbent enters the lower reaction domain from the upper side feed pipe, mixes with the reduced oxygen carrier and flows downward, countercurrently contacting with the upward flowing gas to produce an absorption enhancement reaction. The generated gas products are discharged from the top of the lower reaction domain, separated by a filter, a condenser and a gas separator, and the condensed gas is collected in a tail gas protection tank after adjusting the reaction pressure through a pressure control valve; the generated solid products are discharged from the bottom and separated by screening, and the reduced oxygen carrier flows into the oxidation reactor through a pipeline to countercurrently react with the water vapor entering the reactor from the lower side of the oxidation reactor, and then lifted by air to the air reactor. While the oxygen carrier is lifted in the gas lift pipe, it is oxidized by the air into an oxidized oxygen carrier, and after separation by the gas-solid separator, it re-enters the top of the upper reaction zone; the saturated absorbent flows into the absorbent regeneration reactor through the pipeline and is regenerated, and then enters from the upper side of the lower reaction zone, thus completing a chemical chain hydrogen production cycle.

[0071] To further demonstrate the superiority of the two-stage reactor, the single-stage co-current / countercurrent moving bed and the reactor described in this embodiment were simulated using Aspen Plus software, and the simulation results are shown in Table 1. This embodiment has a higher unit CH4 hydrogen production and CO2 capture rate.

[0072] Table 1 Comparison of performance of four reactors

[0073]

[0074]

[0075] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A two-stage absorption enhanced moving bed reactor, characterized in that: include: the reduction reaction domain in the upper half and the absorption enhancement reaction domain in the lower half; The reduction reaction domain and the absorption enhancement reaction domain are connected through a reduced diameter section, the lower end side wall of the reduction reaction domain is provided with a reaction gas inlet for introducing hydrocarbon fuel, and the upper end side wall of the reduction reaction domain is provided with an exhaust pipe and a feed pipe for introducing solid materials; The lower side wall of the absorption enhancement reaction domain is provided with a reaction gas inlet, the upper side wall of the absorption enhancement reaction domain is provided with an exhaust pipe and a feed pipe for feeding a carbon dioxide absorbent, and the bottom of the absorption enhancement reaction domain is provided with a solid material discharge port; wherein the exhaust pipe of the reduction reaction domain is connected to the reaction gas inlet of the absorption enhancement reaction domain; It also includes an absorbent regeneration reactor, the material inlet of the absorbent regeneration reactor is connected with the solid material discharge port of the absorption enhancement reaction domain, and the material outlet of the absorbent regeneration reactor is connected with the feed pipe of the absorption enhancement reaction domain, so as to allow the absorbent after absorbing carbon dioxide to enter the absorbent regeneration reactor for desorption and then be re-transported to the absorption enhancement reaction domain.

2. The two-stage absorption enhanced moving bed reactor according to claim 1, characterized in that: It also includes a mechanical lifting device, which is arranged between the connecting pipeline of the absorption enhancement reaction zone and the absorbent regeneration reactor, and is used to mechanically lift the absorbent after absorbing carbon dioxide and send it into the absorbent regeneration reactor.

3. The two-stage absorption enhanced moving bed reactor according to claim 1, characterized in that: It also includes a filter, which is arranged at the solid material discharge port at the bottom of the absorption enhancement reaction domain and is used to filter the solid powder in the gas product.

4. The two-stage absorption enhanced moving bed reactor according to claim 1, characterized in that: A filter, a condenser and a gas separator are sequentially arranged at the exhaust pipe on the upper side wall of the absorption enhancement reaction domain, so that the gas products generated by the reaction are collected after filtering, condensing and separating.

5. The two-stage absorption enhanced moving bed reactor according to claim 1, characterized in that: The solid material fed into the feed pipe on the upper side wall of the reduction reaction zone is a hydrocarbon fuel reforming reaction catalyst or an oxygen carrier.

6. The two-stage absorption enhanced moving bed reactor according to claim 1, characterized in that: The reduced diameter section is provided with a cut-off gas inlet for introducing cut-off gas to prevent gas cross-talk between the reduction reaction domain and the absorption enhancement domain.

7. The two-stage absorption enhanced moving bed reactor according to claim 5, characterized in that: It also includes an oxidation reactor and an air reactor, wherein the feed inlet of the oxidation reactor is connected to the solid material discharge port of the absorption enhancement reaction domain, water vapor is introduced into the oxidation reactor to cause an oxidation reaction between the water vapor and the reduced oxygen carrier, the discharge port of the oxidation reactor is connected to the feed inlet of the air reactor, and is used to completely oxidize the partially oxidized oxygen carrier into an oxidized oxygen carrier, and the discharge port of the air reactor is connected to the feed pipe of the upper end side wall of the reduction reaction domain, and is used to send the completely oxidized oxygen carrier into the reduction reaction domain to participate in the reaction again.

8. The two-stage absorption enhanced moving bed reactor according to claim 7, characterized in that: It also includes a screening device, which is arranged at the solid material discharge port of the absorption enhancement reaction domain, the first outlet of the screening device is connected to the feed port of the oxidation reactor, and the second outlet of the screening device is connected to the material inlet of the absorbent regeneration reactor, and is used to separate the reduced oxygen carrier output from the absorption enhancement reaction domain and the absorbent after absorbing carbon dioxide, and send them to the oxidation reactor and the absorbent regeneration reactor respectively.

9. The two-stage absorption enhanced moving bed reactor according to claim 7, characterized in that: It also includes a gas-solid separator, which is arranged between the connecting pipeline of the air reactor and the reduction reaction domain, and is used to perform gas-solid separation on the completely oxidized oxygen carrier, and send the separated oxygen carrier into the reduction reaction domain to participate in the reaction again.

10. The two-stage absorption enhanced moving bed reactor according to claim 1, characterized in that: The main component of the carbon dioxide absorbent in the absorption enhancement reaction zone is Li4SiO4 or Li2ZrO3 or CaO.

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