KR100246079B1 - Reactor and process for preparing synthetic gas - Google Patents

Abstract

The present invention relates to a reactor for producing hydrogen and carbon monoxide (hereinafter referred to as "synthetic gas") and a method for producing a synthesis gas using the same. The reactor of the present invention includes a fuel supply port 1 for supplying fuel and an air inlet ( 2), a mixing section 4 for mixing fuel and air, an electric heater 5 for inducing ignition of the introduced mixed gas, a combustion catalyst layer 6 for promoting combustion, and promoting reforming of water vapor and carbon dioxide It is characterized in that it comprises a reforming catalyst layer (7) and a hydrogen gas outlet (3), the production method of the present invention in the reaction for generating hydrogen and carbon monoxide from methane, carbon dioxide which is the exhaust gas of methane used as a heat source And steam is recovered to the reactor, and excess methane is added and reused as raw materials.

In the process of obtaining hydrogen and carbon monoxide from methane according to the present invention, it is possible to suppress the emission of carbon dioxide, which is currently a problem worldwide, and to reuse the waste heat that has been released into the atmosphere.

Description

Reactor for syngas production and method for producing syngas using the same

The present invention relates to a reactor for producing hydrogen and carbon monoxide (hereinafter referred to as "synthetic gas") and a method for producing a syngas using the same.

Hydrocarbon reforming refers to a process of converting hydrocarbons, especially methane and steam, to hydrogen and carbon monoxide by catalytic reaction at about 800 to 900 ° C. The production of hydrogen and carbon monoxide is carried out through a reaction process as shown in Scheme 1 below on a nickel catalyst at high temperature.

CH ₄ + H ₂ O ↔ CO + 3H ₂

The process using this reaction was first intact at BASF in Germany in 1926 and has already become a global process, with industrial frameworks for thermodynamic studies, catalysts and reaction conditions. In the reforming reaction, water vapor is supplied three times more than raw materials to prevent reverse reaction and coke formation of the catalyst. The reaction temperature is maintained at 600 ~ 900 ℃.

Hydrogen and carbon monoxide, synthesis gases obtained through this reaction, can be used as a raw material for ammonia synthesis, which is an important raw material for fertilizer production, and can be used as a reaction gas for the synthesis of methanol. It can be used as a raw material of the phosphate fuel cell to produce electricity by reacting with.

Since the steam reforming reaction is a strong endothermic reaction (ΔH> 206 KJ / hr), heat supply from the outside is required. To this end, the installation of the burners also uses natural gas (or hydrocarbons) as fuel for the burners. The conventional process uses a flame burner as shown in FIG. 1 and also uses natural gas (or hydrocarbon) as fuel for the burner. In addition, the burned flue gas contains carbon dioxide and water vapor. In the conventional method, only the heat required for the reforming reaction is used, and the hot flue gas (500 to 800 ° C.) containing the remaining carbon dioxide and water vapor after the remaining combustion is discharged to the atmosphere through the flue. Has been. This is unreasonable in terms of the efficiency of energy use because steam boilers used to make separate steams did not use steam, carbon dioxide and heat in exhaust gas.

The present invention is to solve the problems of the prior art as described above, the main purpose is to improve the energy efficiency in the production of hydrogen and carbon monoxide through a reforming reaction. Another object of the present invention is to recycle carbon dioxide and water vapor, which are exhaust gases generated after the combustion of methane supplied as fuel.

1 is a process chart of a conventional steam reforming process,

2 is a cross-sectional view of the reactor of the present invention,

3 is a graph showing the conversion rate of methane,

4 is a graph showing the composition of the product.

* Explanation of symbols for main parts of the drawings

1: fuel supply port 2: air inlet port

3: hydrogen gas outlet 4: mixing part

5: electric heater 6: combustion catalyst

7: modified catalyst 8: support

In the present invention, in the reaction for producing hydrogen and carbon monoxide from methane, supplying the heat required for the reforming reaction and adding excess methane to the carbon dioxide and water vapor, which is the exhaust gas is used as a raw material, the reactor of the present invention Fuel supply port (1) and air inlet (2) for supplying fuel, mixing section (4) for mixing fuel and air, electric heater (5) for inducing ignition of the introduced mixed gas, and promoting combustion It characterized in that it comprises a combustion catalyst layer (6), a reforming catalyst layer (7) and a hydrogen gas outlet (3) for promoting the reforming of water vapor and carbon dioxide.

Hereinafter, the present invention will be described in detail.

In order to generate the synthesis gas CO and 3H ₂ through the prior art, a separate heat must be applied to proceed with the endothermic reaction 1, and this heat is obtained through the reaction shown in the following reaction formula 2.

CH ₄ + 2O ₂ ↔ CO ₂ + 2H ₂ O + △ H

The gases produced by Scheme 2, CO ₂ and H ₂ O, were released into the atmosphere, and the released CO ₂ is an environmental pollutant that has a global greenhouse effect. In addition, the released H ₂ O is released in a state containing heat.

In the present invention, in order to use CO ₂ and H ₂ O released as it is in the prior art for the reaction, a catalytic combustion reaction of methane is used, as shown in Scheme 3 below. Reactions as in Schemes 4 and 5 proceed.

CH ₄ + 3 / 2O ₂ ↔ CO ₂ + H ₂ O

CH ₄ + CO ₂ ↔ 2CO + 2H ₂

CH ₄ + H ₂ O ↔ CO + 3H ₂

Combination of the reaction schemes 3, 4, and 5 can be represented by the overall scheme 6.

3CH ₄ + 3 / 2O ₂ ↔ 3CO + 6H ₂

Therefore, in the present invention, carbon dioxide and water vapor released into the air in the prior art can theoretically generate 3 mol and 6 mol of theoretical carbon monoxide and hydrogen, respectively, with respect to 3 mol of methane injected. It is higher than 1 mol and 3 mol of.

The reactor of the present invention is novel and is configured to be suitable for the production method of the present invention, the cross section of which is shown in FIG.

Methane, which is a fuel, is supplied through the fuel supply port 1, and the supplied fuel is mixed in the mixing unit 4 with the air introduced through the air inlet 2. The mixing ratio of fuel and air is 3: 2, and when this is introduced into the reactor in which the electric heater 5 is operated in advance to maintain the initial reaction temperature of methane at 300 ° C., the mixed gas passes through the mixing unit 4. The vortex is generated and mixed well to start combustion. Once combustion starts, the power of the electric heater 5 is cut off.

Even if the power is cut off, the combustion reaction continues. As a result, methane mixed well with air passes through the combustion catalyst layer 6 to generate carbon dioxide and water, a small amount of hydrogen and carbon monoxide, and some of the secondary catalyst is unreacted. It is moved to the phosphorus reforming catalyst layer 7. In the secondary catalyst, carbon dioxide and water generated from the methane combustion reaction are reacted with unreacted methane to produce hydrogen and carbon monoxide. The combustion catalyst layer 6 and the reforming catalyst layer 7 are formed in a dome shape, and the reforming catalyst layer 7 is formed so as to surround the combustion catalyst layer 6, thereby widening the reaction area and effectively utilizing the heat of combustion generated from the combustion catalyst. The combustion catalyst layer 6 and the reforming catalyst layer 7 are attached to the support 8, respectively.

The syngas produced as a result of the reaction is a high temperature (500 ~ 800 ℃), this heat can increase the overall energy efficiency by preheating the reactant methane and air flowing into the reactor from the finned heat exchanger at the reactor inlet.

Combustion catalyst is preferably Pd-Rh / cordierite which is 1% by weight of Pd and Rh supported on CeO ₂ and wash-coated on cordierite, and the reforming catalyst is NiO, CaO, K It is preferable to use a catalyst in which ₂ O, SiO ₂ , MgO and the like are supported on alumina.

Embodiments of the present invention are as follows.

Example 1

Equilibrium composition of the exhaust gas after the reaction in the present invention was determined using a computer model (ASPEN PLUS Rel.9.3-1). Here, the catalytic combustion reaction of methane as a reactant is to supply 2 moles of oxygen more than 3/2 moles of stoichiometry to increase excess water and calorific value to 3 moles of methane, and the catalytic combustion reaction temperature is 800 ° C. Assumed In addition, it was assumed that the reforming reaction reached chemical equilibrium, and the reactor temperature in the reforming reaction was determined to be determined by the reaction conditions, and the exhaust gas composition at that time was calculated by computer simulation. It is assumed that the reactor is insulated so that heat generated through catalytic combustion of methane can be used for all reforming reactions. As a result of computer simulation, the molar ratios of the products after catalytic combustion and reforming according to the conversion rate of methane during catalytic combustion are shown in Table 1 below, and the graph of temperature-methane conversion rate is shown in FIG.

Computer simulations concluded that when methane is burned on the combustion catalyst, the heat required for reforming reaction can be supplied as catalytic combustion heat when the conversion of methane is 0.45 or more.The exhaust gas temperature at that time is 680 ℃ and the exhaust gas composition It can be seen that 5.069 mol of hydrogen, 2.343 mol of carbon monoxide, 0.147 mol and 0.51 mol of unreacted methane and carbon dioxide are also 0.637 mol of water discharged.

Example 2

99.9% of methane and 21% of oxygen (He base) were used as the reaction gas. Methane and oxygen were adjusted to have a molar ratio of 3 to 2, respectively. The reactor was allowed to pass through the reactor, and the volumetric flow rate of the entire reactor was 131.5 ml / min to allow the methane combustion and reforming reactions to occur continuously. In addition, the outside of the reactor was insulated to prevent the loss of heat generated during catalytic combustion. After the reaction, the flue gas was analyzed using TCD of gas chromatography (Young Lin 600D), and the column was CARBOXEN 1000.

The product obtained at 700 ° C. obtained 5.84 mol of hydrogen corresponding to 97.3% of 6 mol of the theoretical value of Scheme 5 and 2.l2 mol of 3 mol of carbon monoxide of 70.7% of the theoretical value, and 0.62 mol of carbon dioxide and water as reaction by-products. This 0.42 mol was obtained. The composition of the product is shown in Table 2 and 4 below.

In the catalytic combustion reaction of methane, Pd-Rh / cordierite wash-coated with cordierite was used because 1 wt% of Pd and Rh were each supported on CaO ₂ as a catalyst, and for reforming water vapor and carbon dioxide, As a catalyst, a catalyst in which 22 wt% NiO, 13 wt% CaO, 6.5 wt% K ₂ O, 15 wt% SiO ₂ , and ₁₂ wt% MgO was supported on alumina was used.

In the process of obtaining hydrogen and carbon monoxide from methane according to the present invention, since it is possible to exclude the burner device for supplying the steam supply equipment and the reaction heat of the existing process, it is possible to manufacture a small natural gas reformer for the capacity and the same amount Synthesis gas with hydrogen carbon monoxide ratio of 1.7 ~ 2.8 can be manufactured from raw materials of. And by controlling the ratio of methane and air to 3 to 2 as reactants, supplying heat for reforming reaction and generating extra steam There is an advantage that can prevent the carbon deposition phenomenon occurs during the reforming.

In addition, the synthesis gas can be obtained with a yield of 2.3 times that of the existing reforming equipment (generated hydrogen, carbon monoxide 9 mol / existing 4 mol). In addition, the emission of carbon dioxide, which is currently a problem worldwide, has a 70% emission reduction effect compared to the existing process (in the result of the present invention, since 0.62 mol of carbon dioxide is produced at the reaction temperature of 700 ° C., 70% ((2-0.62) / 2), and also can reuse the waste heat that has been released into the atmosphere during the time to increase energy use efficiency.

Claims (5)

A fuel supply port 1 and an air inlet port 2 for supplying fuel and oxygen, a mixing unit 4 for mixing fuel and air, an electric heater 5 for inducing ignition of the introduced mixed gas, combustion A reforming catalyst layer (7) and a hydrogen gas outlet (3) for promoting the reforming catalyst layer (7) is formed outside the combustion catalyst layer (6), and the combustion catalyst layer (6) has a Pd and Rh of 1% by weight, respectively. It is supported on each CeO _{2 and} is wash-coated to cordierite, and the reforming catalyst layer 7 includes NiO, CaO, K ₂ O, SiO ₂ , and MgO supported on alumina. Manufacturing reactor. The reactor for syngas production according to claim 1, characterized in that the combustion catalyst layer (6) and the reforming catalyst layer (7) are attached to the support (8). The reactor for syngas production according to claim 1, wherein the combustion catalyst layer (6) and the reforming catalyst layer (7) have a dome structure. In the reaction where methane is used as the heat source and carbon monoxide and hydrogen are generated from the methane through reforming reaction, carbon dioxide and water vapor, which are the exhaust gas of methane used as the heat source through the reactor according to claim 1, are not discharged. Method of producing a synthesis gas, characterized in that to recycle the carbon dioxide and water vapor as a raw material by reacting by adding excess methane to the mixed gas of carbon dioxide and water vapor to induce the reaction schemes 3 to 6. Scheme 3 CH ₄ + 3 / 2O ₂ ↔ CO ₂ + H ₂ O Scheme 4 CH ₄ + CO ₂ ↔ 2CO + 2H ₂ Scheme 5 CH ₄ + H ₂ O ↔ CO + 3H ₂ [Scheme 6 (whole scheme of schemes 3, 4, 5)] 3CH ₄ + 3 / 2O ₂ ↔ 3CO + 6H ₂ 5. A process according to claim 4, wherein the combustion reaction and the reforming reaction occur simultaneously in the reactor.

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