CN103086325A - Natural gas hydrogen production reactor and hydrogen production process thereof - Google Patents

Abstract

A natural gas hydrogen production reactor and its hydrogen production process. The reactor is composed of multiple different reaction chambers. The entire reactor includes five reaction areas including reforming, catalytic combustion, pre-catalytic combustion, conversion, and purification. The three areas of material gasification and material preheating increase the compactness of the reactor, reduce the processing difficulty of the reactor, and facilitate scale expansion; the flow mode of the material flow between different reaction chambers is mainly parallel flow and countercurrent flow , the energy matching between different internal logistics is reasonable, and the heat transfer efficiency is high. The reactor of the present invention can be widely used in coupled reaction systems with strong heat release and heat absorption, and is especially suitable for hydrogen source systems of 1-10kW fuel cell distributed power sources.

Description

A natural gas hydrogen production reactor and its hydrogen production process

technical field

The invention belongs to the technical field of hydrogen energy and fuel cells, and in particular relates to a natural gas hydrogen production reactor and a hydrogen production process thereof.

Background technique

my country is rich in natural gas resources, most of which are mainly distributed in remote areas such as the west and northwest, resulting in high costs for compression, transportation, storage, and utilization. At present, in order to realize the economical utilization of natural gas, natural gas is usually processed as the initial raw material to produce compounds such as multi-carbon hydrocarbons and alcohols, which are mainly completed in two steps: first, methane is converted into CO _and H Synthesis gas is converted into multi-carbon hydrocarbons and alcohols, such as by FT synthesis. Synthesis gas can be prepared from almost carbon-containing compounds, such as coal and natural gas, etc. The cost of producing synthesis gas is variable, mainly determined by H ₂ /CO ratio, raw materials, preparation process, scale, system integration and other factors. Syngas has a wide range of uses and can be used as industrial raw materials to produce ammonia, hydrogen, methanol, etc.

In recent years, the hydrogen production process has attracted more and more attention, and the application targets are mainly stationary and mobile heating and power supply systems. There are four main reaction pathways in the hydrogen production process of natural gas: steam reforming, _CO2 reforming, partial oxidation and autothermal reforming. The respective reaction processes are as follows:

CH _4(g) +H ₂ O _(g) →CO _(g) +3H _2(g) +Q.------(1)

CH _4(g) +CO _2(g) →2CO _(g) +2H _2(g) +Q---(2)

CH _4(g) +0.5O _2(g) →CO _(g) +2H _2(g) -Q------(3)

CH _4(g) +2O _2(g) →CO _2(g) +2H ₂ O _(g) -Q ₀ -----(4-0)

CH _4(g) +H ₂ O _(g) →CO _(g) +3H _2(g) +Q ₁ ------(4-1)

Among them, the steam reforming hydrogen production process has the most mature technology, the highest hydrogen production, and the most widely used. As shown in Equation (1), steam reforming of methane to hydrogen is an endothermic process, so it is necessary to provide sufficient external heat supply to ensure the smooth progress of steam reforming of methane. The supply of external heat can be provided in many ways, and the combustion and heat release of carbon-containing compounds is one of them. In the natural gas hydrogen production reactor, the effective control and management of heat, especially the reasonable matching and coupling of endothermic and exothermic reactions when multiple reactions are carried out at the same time, is very important, which will directly affect the reaction temperature, conversion rate, reactor efficiency, etc. For example, in the same reactor, when the reaction heat absorption and external heat supply are unbalanced, the reaction temperature will be unstable. If the temperature is too high, it will cause local hot spots, and if the temperature is too low, it will cause the hydrogen production rate to increase. Decrease until the reaction ceases.

At present, the fixed-bed reactors for reforming hydrogen production generally adopt the cylindrical type. Although this kind of reactor is simple to manufacture, it has certain difficulties in improving the reaction capacity. To improve the reaction capacity, it is necessary to consider how to increase the heat exchange area and the loading amount of the catalyst. For this cylindrical fixed bed reactor, the general method to improve the reaction capacity is to increase the diameter of the cylinder to increase the heat exchange area and catalyst capacity of the reactor. The loading amount of the catalyst, but this will cause uneven radial temperature distribution, which will make the reaction difficult to control and increase the occurrence of side reactions; if it is changed to simply increasing the height of the fixed bed reactor, this will also cause axial temperature distribution The inhomogeneity of the reaction leads to a decrease in the conversion efficiency of the reaction, a decrease in selectivity, and a decrease in the energy efficiency of hydrogen production. In addition, when the power requirement is high to a certain extent, this cylindrical reactor is not suitable for mobile decentralized hydrogen production due to its large volume. Therefore, some scholars have conducted research on compact reforming hydrogen production reactors, and how to improve the heat transfer efficiency between exothermic and endothermic sources is a core issue. How to design a hydrogen production reactor that can ensure a certain scale of hydrogen production reaction smoothly and is easy to process in a limited space is another core issue in the study of compact reforming hydrogen production reactors.

Contents of the invention

The object of the present invention is to provide a natural gas hydrogen production reactor and its hydrogen production process. The hydrogen production reactor can solve: 1. Improve the problem of uneven temperature distribution in traditional cylindrical fixed bed reactors; The volume of the device can meet the needs of distributed hydrogen sources; 3. Reduce the heat transfer resistance between reforming heat absorption and combustion heat release, improve heat transfer efficiency, and improve reaction efficiency and reaction selectivity.

The invention provides a natural gas hydrogen production reactor, which is composed of a plurality of different reaction chambers, including catalytic combustion (1b), reforming (1c), pre-catalytic combustion (1d), conversion (1f) 1, purification (1h) 5 reaction areas and material gasification (1a), two material preheating (1e and 1g) 3 areas; two raw material gas inlets for hydrogen production are (12 and 13), and one product gas outlet (14);

Among them, the four areas of material gasification (1a), reforming (1c), conversion (1f) and purification (1h) are connected in sequence, and the two areas of material preheating (1e and 1g) are connected with catalytic combustion (1b), preheating The catalytic combustion (1d) reaction zones are connected. The feed gas entering from the inlets (12 and 13) first enters the mixing distributor (1i) after being preheated.

In the natural gas hydrogen production reactor provided by the present invention, the whole reactor is composed of a plurality of different regions, and the purpose of expanding the reaction scale can be achieved by increasing the number and size of the reaction regions in parallel.

The present invention also provides a hydrogen production process using the reactor, the process is as follows: the combustible gas natural gas and air first enter the corresponding material preheating (1e and 1g) areas respectively from the inlets (12 and 13), and then In the pre-catalytic combustion (1d) reaction area, the catalytic combustion reaction is mixed and started by the mixing distributor (1i), and the released heat is transferred to the reforming (1c) reaction area and the material preheating (1e) area through convection and heat conduction ; The combustion gas enters the catalytic combustion (1b) reaction area after passing through the pre-catalytic combustion (1d) reaction area to continue the catalytic combustion reaction, and transfers a large amount of heat to the material gasification (1a) area and reforming (1c) reaction area ; The reaction raw material enters the hydrogen production reactor in turn from the inlet (11) into the four areas of material gasification (1a), reforming (1c), transformation (1f) and purification (1h), and finally at the reactor outlet (14) The hydrogen-rich mixed gas that meets the requirements can be obtained everywhere.

In the hydrogen production process provided by the present invention, the three reaction zones of reforming (1c), conversion (1f) and purification (1h) of the reactor are all filled with different catalysts, and the reforming (1c), conversion (1f) And purification (1h) The catalysts in the three reaction areas are particle catalysts or wall-supported catalysts.

In the hydrogen production process provided by the present invention, the material preheating (1e and 1g) areas of the reactor are filled with porous media materials with large heat capacity to improve the material preheating effect.

In the hydrogen production process provided by the present invention, the catalytic combustion (1b) and pre-catalytic combustion (1d) areas of the reactor are filled with catalysts, and the catalysts are granular catalysts or wall-mounted catalysts; catalytic combustion (1b) and pre-catalytic combustion The catalyst in the (1d) area is the same type of catalytic combustion catalyst or a catalyst with better low-temperature activity is loaded in the pre-catalytic combustion (1d) area.

In the hydrogen production process provided by the present invention, the internal heat utilization of the reactor is reasonable, and better heat coupling is realized between the exothermic reaction and endothermic reaction, gasification and cooling, and the material gasification (1a) and catalytic combustion (1b) Between areas, between reforming (1c) and pre-catalytic combustion (1d) areas, between material preheating (1e and 1g) and conversion (1f) areas, the flow of streams is co-current; in reforming (1c ) and catalytic combustion (1b) area, between pre-catalytic combustion (1d) and material preheating (1e) area, between purification (1h) and material preheating (1g) area, the flow mode of the stream is countercurrent.

In the hydrogen production process provided by the present invention, the combustible gas natural gas and air first pass through the corresponding material preheating (1e and 1g) areas before the catalytic combustion reaction, and the preheated gas is easier to start the catalytic combustion reaction; the combustible gas After preheating, the natural gas and air first enter the mixing distributor (1i). In the mixing distributor (1i), on the one hand, the natural gas and air can be fully mixed, and on the other hand, they can evenly enter through the mixing distributor (1i). Pre-catalytic combustion (1d) region.

In the hydrogen production process provided by the present invention, the catalytic combustion of combustible natural gas and air goes through two stages of pre-catalytic combustion and catalytic combustion. After the natural gas passes through the pre-catalytic combustion (1d) and catalytic combustion (1b) areas, the natural gas in the exhaust gas is burned The content is below 20ppm.

In the hydrogen production process provided by the present invention, the concentration of carbon monoxide in the product gas at the outlet (14) of the reactor is between 0-10ppm, which can meet the requirements of the proton exchange membrane fuel cell on the quality of the gas source, and can be directly supplied to the proton exchange membrane fuel battery and generate corresponding electricity.

The technical solution adopted by the present invention is: 1. The gas distributor is used to make the material distribution in the reaction chamber relatively uniform, and the structure similar to a flat plate is adopted to make the reactor structure compact and avoid the temperature caused by the long radial direction. Uneven distribution; 2. The whole reactor integrates multiple areas such as material gasification, material preheating, catalytic combustion, reforming, pre-catalytic combustion, conversion, and purification, which greatly reduces the volume of the reactor and the processing difficulty It is also reduced accordingly, which is beneficial to the scale-up of the hydrogen production reactor. 3. Utilize the reasonable arrangement of different areas inside the reactor to maximize the use of the internal heat of the reactor; achieve better heat coupling between exothermic reaction and endothermic reaction, gasification and cooling, so as to increase heat transfer Effect, the purpose of improving conversion rate and selectivity.

Description of drawings

Figure 1 is a schematic diagram (three-dimensional) of a natural gas hydrogen production reactor;

Figure 2 is a schematic diagram of a natural gas hydrogen production reactor (top view);

Fig. 3 is a schematic diagram of the material flow of a natural gas hydrogen production reactor;

Fig. 4 is the change of CO concentration in the outlet product gas of the natural gas hydrogen production reactor with time.

Detailed ways

The following examples will further illustrate the present invention, but do not limit the present invention thereby.

The natural gas hydrogen production reactor (Fig. 1) of the present invention is composed of a plurality of different reaction chambers. The whole reactor body adopts a flat plate structure, which includes material gasification (1a), catalytic combustion ( 1b), reforming (1c), pre-catalytic combustion (1d), material preheating (1e), transformation (1f), material preheating (1g) and purification (1h). The natural gas and water required for the hydrogen production reaction enter through the inlet (11), and are provided to the user through the outlet (14) after gasification, reforming, conversion and purification; the energy for the entire hydrogen production process comes from the catalysis of natural gas Combustion reaction, the raw material natural gas and air of the catalytic combustion reaction enter the hydrogen production reactor through the inlets (12 and 13) respectively.

The natural gas hydrogen production reactor in the present invention (Fig. 1) can use methanol, ethanol and other alcohols as well as natural gas, gasoline and other hydrocarbons as raw materials. In order to briefly explain some situations in the actual implementation process, methane (CH ₄ ) and water are chosen as examples to illustrate that catalytic combustion (1b) and pre-catalytic combustion (1d) reaction areas mainly carry out catalytic combustion reactions:

CH _4(g) +2O _2(g) →CO _2(g) +2H ₂ O _(g)

Its main functions are: 1. Provide heat for the preheating and gasification of materials; 2. Provide energy for the reforming reaction in the hydrogen production reaction process.

The main reactions in the reforming (1c) reaction area are:

CH _4(g) +2H ₂ O _(g) →CO _2(g) +4H _2(g)

CH _4(g) +H ₂ O _(g) →CO _(g) +3H _2(g)

Transformation (1f) mainly reacts in the reaction region:

CO _(g) +H ₂ O _(g) →CO _2(g) +H _2(g)

The main reactions in the purification (1h) reaction area are:

CO _(g) + O _{2 (g)} → CO _{2 (g)}

_H2(g) +O2 _(g) → _{H2O (g)}

Figure 3 is a schematic diagram of the material flow of the natural gas hydrogen production reactor. When the system is running, CH ₄ and air enter the respective material preheating (1e and 1g) areas through the inlet (12) and inlet (13) respectively in a certain proportion. The material preheating (1e and 1g) areas of the reactor are filled with porous media materials with large heat capacity, which can improve the material preheating effect. After preheating, CH ₄ and air enter the mixing area (305) of catalytic combustion reaction materials from the outlets (304 and 303) of each material preheating area, and then CH ₄ and air enter into the pre-catalysis through the mixing distributor (1i). Burning (1d) area. In the mixing distributor (1i), natural gas and air can be fully mixed on the one hand, and on the other hand can evenly enter the pre-catalytic combustion (1d) area through the mixing distributor (1i). The preheated, mixed and uniformly distributed CH ₄ and air rapidly undergo a catalytic combustion reaction in the pre-catalytic combustion (1d) area, releasing a large amount of heat, which can rapidly increase the overall temperature of the reactor. The gas after pre-catalytic combustion enters the catalytic combustion (1b) area from the outlet (306) of the pre-catalytic combustion (1d) area through the inlet (307) of the catalytic combustion (1b) area. In the catalytic combustion (1b) area, the incompletely combusted CH ₄ and air continue to carry out the catalytic combustion reaction, and at the outlet of this area, the CH ₄ content in the combustion tail gas is finally controlled below 20ppm. The high-temperature combustion tail gas that is nearly completely converted passes through the catalytic combustion (1b) area and performs efficient heat exchange with the low-temperature hydrogen production raw material that enters the material gasification (1a) area. While preheating and gasifying the hydrogen production raw material, the temperature of the combustion tail gas drops sharply and is finally discharged from the outlet (308) of the catalytic combustion (1b) zone.

When the reforming (1c), conversion (1f) and purification (1h) reaction areas reach a suitable reaction temperature, a certain proportion of CH ₄ and liquid water mixture is introduced into the hydrogen production raw material inlet (11), and the material gas passes through Heat exchange with the high-temperature tail gas in the catalytic combustion (1b) area during the gasification (1a) area. After the material is gasified, the outlet (32) of the material gasification (1a) area passes through the buffer area (3A) of the hydrogen production raw material and passes through reforming The entrance (33) of the (1c) zone enters the reforming (1c) zone. In the reforming (1c) area, the raw materials for hydrogen production undergo reforming reactions, and a reformed mixed gas containing hydrogen, carbon monoxide, carbon dioxide and other gases is initially obtained. Due to the existence of carbon monoxide in the mixed gas produced in the reforming (1c) area, this gas cannot be supplied to the proton membrane fuel cell for the time being. Therefore, after the mixed gas produced in the reforming (1c) area flows out from the outlet (34) of the reforming (1c) area, the buffer area (3B) of the reformed mixed gas enters through the inlet (35) of the transforming (1f) area Shift (1f) region, where the shift reaction takes place, the carbon monoxide concentration in the reformed mixed gas drops to an order of magnitude of about 1%, which is still unable to meet the use requirements of the proton membrane fuel cell. Therefore, this part of the reaction gas flows out from the outlet (36) of the conversion (1f) area, and then enters the purification (1h) area from the inlet (37) of the purification (1h) area through the buffer area (3C) of the conversion mixed gas, Selective oxidation of carbon monoxide is carried out in this area, and the concentration of carbon monoxide in the reformed mixed gas finally drops below 10ppm, which can be provided to the user of the fuel cell through the outlet (14) of the purification (1h) area.

Fig. 4 shows that in the specific implementation process of the present invention, the carbon monoxide concentration at the outlet (14) of the purification (1h) area is always controlled below 10ppm within 1000 hours of experimental testing time, which can fully meet the design requirements of the present invention.

The natural gas hydrogen production reactor of the present invention can also be widely used in coupled reaction systems with strong heat release and heat absorption, and is especially suitable for hydrogen source systems of 1-10kW fuel cell distributed power sources.

Claims (10)

1. A natural gas hydrogen production reactor, characterized in that: the reactor is composed of a plurality of different reaction chambers, including catalytic combustion (1b), reforming (1c), pre-catalytic combustion (1d), conversion ( 1f), purification (1h) 5 reaction areas and material gasification (1a), two material preheating (1e and 1g) 3 areas; two feed gas inlets for hydrogen production are (12 and 13), one product Gas outlet (14); Among them, the four areas of material gasification (1a), reforming (1c), conversion (1f) and purification (1h) are connected in sequence, and the two areas of material preheating (1e and 1g) are connected with catalytic combustion (1b), preheating The catalytic combustion (1d) reaction areas are connected; the feed gas entering from the inlets (12 and 13) first enters the mixing distributor (1i) after being preheated. 2. The natural gas hydrogen production reactor according to claim 1, characterized in that: the reactor is composed of a plurality of different regions, and the purpose of expanding the reaction scale can be achieved by increasing the number and size of the reaction regions in parallel. 3. A hydrogen production process using the reactor described in claim 1, characterized in that: the process is: the combustible gas natural gas and air first enter the corresponding material preheating (1e and 1g) respectively from the inlets (12 and 13) ) area, and then in the pre-catalytic combustion (1d) reaction area, mix and start the catalytic combustion reaction through the mixing distributor (1i), and the released heat is transferred to the reforming (1c) reaction area and material preheating by convection and heat conduction (1e) area; the combustion gas enters the catalytic combustion (1b) reaction area after passing through the pre-catalytic combustion (1d) reaction area to continue the catalytic combustion reaction, and transfers a large amount of heat to the material gasification (1a) area and reforming ( 1c) Reaction area; the reaction raw material enters the four areas of material gasification (1a), reforming (1c), transformation (1f) and purification (1h) of the hydrogen production reactor sequentially from the inlet (11), and finally in the reactor The hydrogen-rich mixed gas meeting the requirements is obtained at the outlet (14). 4. According to the hydrogen production process described in claim 3, it is characterized in that: the reforming (1c), conversion (1f) and purification (1h) three reaction areas of the reactor are all filled with different catalysts, and the reforming The catalysts in the three reaction zones of (1c), transformation (1f) and purification (1h) are particle catalysts or wall-supported catalysts. 5. The hydrogen production process according to claim 3, characterized in that: the material preheating (1e and 1g) areas of the reactor are filled with porous media materials with large heat capacity to improve the material preheating effect. 6. The hydrogen production process according to claim 3, characterized in that: the catalytic combustion (1b) and pre-catalytic combustion (1d) areas of the reactor are filled with catalysts, and the catalysts are particle catalysts or wall-mounted catalysts; The catalysts in the combustion (1b) and pre-catalytic combustion (1d) areas are the same type of catalytic combustion catalysts or a catalyst with better low-temperature combustion activity is loaded in the pre-catalytic combustion (1d) area. 7. According to the hydrogen production process described in claim 3, it is characterized in that: the internal heat utilization of the reactor is reasonable, and better heat coupling is realized between exothermic reaction and endothermic reaction, gasification and cooling, and the material gasification ( Between 1a) and catalytic combustion (1b) areas, between reforming (1c) and pre-catalytic combustion (1d) areas, between material preheating (1e and 1g) and transformation (1f) areas, the flow mode of the stream is Co-current; between reforming (1c) and catalytic combustion (1b) zones, between precatalytic combustion (1d) and material preheating (1e) zones, between purification (1h) and material preheating (1g) zones , the flow mode of the logistics is countercurrent. 8. The hydrogen production process according to claim 3, wherein the combustible gas natural gas and air first pass through the corresponding material preheating (1e and 1g) areas before the catalytic combustion reaction, and the preheated gas is more It is easy to start the catalytic combustion reaction; combustible gas natural gas and air first enter the mixing distributor (1i) after preheating, and in the mixing distributor (1i), the natural gas and air can be fully mixed on the one hand, and on the other hand can be The mixing distributor (1i) enters the pre-catalytic combustion (1d) zone uniformly. 9. The hydrogen production process according to claim 3, characterized in that: the catalytic combustion of combustible gas natural gas and air undergoes two stages of pre-catalytic combustion and catalytic combustion, and natural gas undergoes pre-catalytic combustion (1d) and catalytic combustion (1b) After the zone, the natural gas content in the combustion tail gas is below 20ppm. 10. The hydrogen production process according to claim 3, characterized in that: in the product gas at the outlet (14) of the reactor, the concentration of carbon monoxide is between 0-10ppm, which can meet the requirements of proton exchange membrane fuel cells for gas source quality , directly provide to the proton exchange membrane fuel cell, and produce corresponding electric power.

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