DE102008027882A1 - Preparing carbon monoxide rich, methane-poor gas, comprises autothermal reforming of hydrocarbon-containing fuel with carbon dioxide, steam and an oxidant - Google Patents

Abstract

Preparing carbon monoxide rich, methane-poor gas (synthesis gas), comprises catalytic partial oxidation (autothermal reforming) of hydrocarbon-containing fuel with carbon dioxide, steam and an oxidant, where the synthesis gas is extracted as a product gas of autothermal reforming process with a temperature of greater than 1100[deg] C. An independent claim is included for a device with a refractory lining for the production of carbon monoxide rich, methane-poor gas (synthesis gas) comprising autothermal reforming reactor for executing the autothermal reforming process, and a reactor burner over which the use materials in the reaction chamber of the autothermal reforming reactor is contacted.

Description

The invention relates to a method for producing a low-carbon, low-methane gas (synthesis gas), wherein a hydrocarbon-containing use (fuel) together with carbon dioxide (CO ₂ ) and / or water vapor and an oxidizing agent by catalytically assisted partial oxidation (autothermal reforming or ATR ) is implemented.

Farther The invention relates to a device for implementation the method according to the invention.

The Synthesis gas production is an important step in the manufacturing process a variety of substances such as ammonia or methanol, as well in the production of synthetic fuels from natural gas (GTL). The preferred process by which the syngas is produced depends on the target product and the plant capacity from. The production of hydrogen is mostly based on the principle Steam reforming in externally heated tube reformer. For the production of synthesis gas for methanol production In large plants, the autothermal reform has prevailed. For the production of synthesis gas in GTL plants, which after the Fischer-Tropsch process will work, both autothermal reforming as well as a combination of partial oxidation without catalyst (POX) and steam reforming used in the tube reformer.

In steam reforming in the tube reformer, a preheated hydrocarbonaceous feed is mixed with steam and passed through catalyst tube filled reformer tubes. The catalyst accelerates the steam reforming of the hydrocarbons and at the same time supports the so-called water gas shift reaction. For example, if the hydrocarbonaceous feedstock is methane, the endothermic reforming reaction will follow the equation CH ₄ + H ₂ O⇔CO + 3H ₂ (1) and the exothermic water gas shift reaction according to the equation CO + H ₂ O⇔CO ₂ + H ₂ (2) from. Since the reforming reaction consumes more energy than the water gas shift reaction provides, the reformer tubes must be externally heated with burners or hot process gases to maintain a sufficient reaction temperature. Due to the strength properties of the pipe material (nickel-containing stainless steels), the reaction temperatures are limited to 800-900 ° C and the reaction pressures to 20-40 bar. In these operating parameters, the implementation of hydrocarbons in use is incomplete. In order to achieve the highest possible degree of conversion and at the same time to minimize soot formation in the reformer tubes, an excess of steam is used so that the ratio of steam to carbon (D / C ratio) is between 2 and 4, depending on the temperature and the desired synthesis gas composition.

In the partial oxidation without catalyst, synthesis gas is produced by reacting a preheated hydrocarbonaceous feed at temperatures between 1300 and 1500 ° C and pressures up to 150 bar with an oxidizing agent. The high reaction pressures and operating temperatures are made possible by the fact that the reaction space is encapsulated with a heat insulation against an external pressure-resistant steel jacket. Since only small amounts of water vapor (flushing steam) are supplied with the starting materials, the D / C ratio is i. Gen. less than 0.1. The heat required for the reforming must be generated internally by oxidation reactions. For the oxidation, oxygen is added in an amount which is insufficient for complete conversion of the hydrocarbons. The reforming reaction proceeds in the gas phase without catalyst. If, for example, methane is used as an insert, the exothermic conversion takes place according to the following equations: CH ₄ + 2 O ₂ ⇒ CO ₂ + 2 H ₂ O (3) 2CH ₄ + O ₂ ⇒ 2CO + 4H ₂ (4)

at the autothermal reforming is a reactor (ATR reactor) with a preheated hydrocarbonaceous feed, a also preheated oxidizing agent and carbon dioxide and / or Steam is charged. The typical D / C ratio is between 0.3 and 1.0. Characteristic of the autothermal reforming is the high flexibility of the process, which is a choice the reaction parameter (hydrocarbonaceous use, D / C ratio, Temperature, pressure) in a wide range. Typically, the working temperature of an ATR reactor is intermediate 900 and 1500 ° C and the working pressure between 20 and 40 bar. As hydrocarbon-containing operations are natural gas, LPG and naphtha suitable.

From a process engineering point of view, the ATR is a combination of POX with increased steam supply and subsequent steam reforming in a catalyst bed. The energy for maintaining the endothermic reforming reaction is in the combustion chamber of the ATR reactor by the partial oxidation of the hydrocarbon containing use. From the combustion chamber, the hot gas flows into the, often designed as a packed bed, catalyst bed in which the steam reforming takes place. In order to cover the heat losses of the reformer, the amount of oxidizing agent is adjusted so that the overall process (heating of the starting materials, partial oxidation, reforming and water-gas shift reaction) is slightly exothermic. The synthesis gas exits the catalyst bed at a temperature (exit temperature) that is significantly lower than the combustion chamber temperature. For example, it is about 1100 ° C when the average combustion chamber temperature is about 1450 ° C. The typical D / C ratio is between 0.3 and 1, while the ratio of oxygen to hydrocarbon-bound carbon (O ₂ / C ratio) is between 0.52 and 0.7.

ATR reactors are i. Gen. vertical cylinders with a pressure-resistant Steel mantle up with a cone and down with a Dished or basket bottom are completed. For protection the steel mantle from heat is inside the ATR reactors a heat-insulating lining made of refractory Built in stones and refractory concrete enclosing a reaction space, which serves as a combustion chamber in its upper part and which in its upper part bottom area is filled with catalyst material. At the top of the cone is a burner (reactor burner) arranged over the the starting materials are introduced into the reaction space. The flame temperatures in the combustion chamber are typically between 1600 and 2000 ° C. As walling usually only for temperatures <1600 ° C are designed, the construction of the lining with a Length / diameter ratio of <3 relatively bulky, so that there is a big gap between lining and flame consists. The thermal insulation consists of refractory bricks, as a statically self-supporting structure in the reactor shell with be masonry refractory mortar.

A carbon monoxide-rich synthesis gas with a H ₂ / CO ratio between 1 and 3, as required for example for the methanol or the Oxogasproduktion or in GTL process is, according to the prior art by steam reforming with optional subsequent autothermal reforming or partial Oxidation generated. Despite the elaborate process procedure, a synthesis gas produced in this way still has CH ₄ residual contents between 2000-6000 ppm. For certain applications, such. As the Oxogasproduktion, but lower CH ₄ residual levels are required so that the synthesis gas must be subjected before its use a treatment in which its methane content is reduced.

task The invention is a method of the type described above and to provide a device for carrying it out, which make it possible, a synthesis gas with high CO content and low methane content in a simpler and more economical way to produce, as this is possible in the prior art is.

The asked task is the method according to the invention thereby solved that using the synthesis gas as a product gas of autothermal reforming a temperature of more than 1100 ° C is recovered.

The recovery of the synthesis gas having a temperature of more than 1100 ° C is equivalent to the fact that the product gas produced in the autothermal reforming exits the catalyst bed with a temperature which is higher than 1100 ° C and thus higher than in the state of Technology. By increasing the exit temperature of the auto-thermal reforming according to the invention, a shift of the reforming equilibrium toward lower CH ₄ contents in the product or synthesis gas is effected. An additional treatment step for reducing the methane content can therefore be dispensed with.

As Experiments have shown, the inventive Process surprisingly carried out with a catalyst be, as well as the state of the art in ATR reactors is used. Although the elevated temperatures cause sintering of the catalyst material, which, however, no or only an insignificant impact on the specific sales performance Has.

refinements of the method according to the invention provide that the synthesis gas is generated at a temperature between 1100 and 1400, preferably between 1100 and 1250, and more preferably between 1130 and 1200 ° C.

The method according to the invention is suitable Generating synthesis gases that cover a wide pressure range. It makes sense to produce a synthesis gas with a pressure that between 1 and 100, preferably between 5 and 80, and more preferably between 10 and 40 bar (a).

For the reforming step of the process according to the invention, a large number of catalysts can be used, in particular those which are also used in an autothermal reforming according to the prior art. With particular advantage, however, a catalyst is used which consists of a catalyst support and a catalytically active material attached to the catalyst support, wherein the catalyst support is preferably aluminum oxide (Al ₂ O ₃ ) or zirconium oxide (ZrO ₂ ) and in the catalytically active material is preferably nickel, rhodium or ruthenium.

The carbon monoxide content in the synthesis gas is primarily dependent on the quantities of carbon dioxide and / or water vapor used. Both quantities also influence the position of the equilibria of the reactions taking place during the autothermal reforming and thus the methane concentration in the synthesis gas. The autothermal reforming allows the amounts of carbon dioxide and / or water vapor used to vary widely and thus adapt the composition of the synthesis gases their use. Embodiments of the method according to the invention therefore provide that the fuel so much water vapor and / or carbon dioxide are admixed that the ratio of water vapor and the bound carbon in the hydrocarbons (D / C ratio) between 0 and 2, preferably between 0.1 and 1.0 and more preferably between 0.2 and 0.6 mol / mol and the ratio of carbon dioxide and the hydrocarbon-bound carbon (CO ₂ / C ratio) is between 0 and 3, preferably between 0.5 and 2 , 0 and more preferably between 0.6 and 1.0 mol / mol.

Another quantity that affects the synthesis gas composition is the ratio of oxygen to the carbon-bonded carbon (O ₂ / C ratio). Conveniently, the O ₂ / C ratio is between 0.5 and 0.9, and preferably between 0.55 and 0.8 mol / mol.

In addition, the invention relates to a device for producing a low-carbon, low-methane gas (synthesis gas), comprising a refractory lined, pressure-resistant reactor (ATR reactor), in which a hydrocarbon-containing feed (fuel) together with carbon dioxide (CO ₂ ) and / or water vapor and an oxidizing agent by catalytically assisted partial oxidation (autothermal reforming or ATR) can be implemented and a reactor burner, via which the starting materials are introduced into the combustion chamber of the ATR reactor.

The asked task is device-side according to the invention solved by the synthesis gas as product gas the ATR reactor with a temperature of more than 1100 ° C is removable.

For the use in the device according to the invention a number of different ATR reactors are suitable. So can it is for example a ATR reactor according to the prior art, as described in, for example, Hydrocarbon Processing / March 2000, p 100 is described. Such a reactor consists of a a refractory lined reactor vessel, the in its largely cylindrically shaped lower reaction space a bed suitable for steam reforming Contains catalyst. Above the catalyst bed there is a conically tapering combustion chamber upwards whose highest point a burner is arranged. The catalyst bed must be carried out with a large inflow area be around the required gas velocities of only 1-1.5 m / s to reach. This results in the typical bulbous shape this ATR reactor, where the ratio of reaction space length to the reaction space diameter is less than three. Due The geometric conditions can be strong in the combustion chamber Form circulation flow, which for a desired Homogenization of the combustion chamber temperature ensures.

In the German Offenlegungsschrift DE10320965 , the disclosure of which is incorporated in the present specification with the citation, a tubular reactor for the conversion of gas streams at high temperatures is described, the slender, cylindrical reaction chamber favors a directed gas flow and prevents the formation of large-scale circulation flows. This tube reactor makes it possible to significantly increase the conversion efficiency compared to a bulbous reactor described above. A variant of the device according to the invention therefore provides that the ATR reactor is designed as a vertical tubular reactor having a catalyst bed in the lower part of its reaction space. Conveniently, the ratio of length to diameter of the reaction space is between 2 and 20, but preferably between 3 and 10. Since due to the slender reactor design relatively high gas velocities of 10-20 m / s are achieved, the specific pressure drop in the catalyst bed should be relatively low to reduce the pressure loads in the catalyst bed and its support. It makes sense, therefore, the catalyst bed is designed as a monolithic, coated with catalyst material honeycomb structure.

A further variant of the device according to the invention provides that only the combustion chamber of the ATR reactor is designed as a vertical tubular reactor. Such an ATR reactor is in the German Offenlegungsschrift DE 10 2005 026 881 whose disclosure content with the citation is also fully incorporated into the present description. The combustion chamber, which contains no internals, can be operated as a POX reactor. It is connected to at least one catalyst-filled steam reforming reactor, to which gas formed in the POX reaction can be fed. Between the combustion chamber and the or the steam reforming reactors, there is expediently a device for supplying steam via which water vapor required for the steam reforming of the gas formed in the POX reaction can be added. The catalyst material is present in the steam reforming reactor in the form of a packed bed or as a monolithic honeycomb structure. Conveniently, the ratio of length to diameter of the combustion chamber is between 6 and 16, but preferably between 9 and 14.

One embodiment of the device according to the invention provides that the reactor burner is designed as a gas-cooled burner, which is preferably a swirl burner, as described for example in the German Offenlegungsschrift DE10332860 is described. Conveniently, the reactor burner is designed so that it can also be used as a preburner for heating the cold ATR reactor.

A further embodiment of the device according to the invention provides that the refractory lining of the ATR reactor at least is executed clamshell, wherein the outer Shell composed of molded parts, which consist of fiber material.

A further embodiment of the device according to the invention provides that the inner, the reaction space forming shell of the refractory lining is constructed of dry ZrO ₂ -Steinen set.

A further embodiment of the device according to the invention provides that the ATR reactor contains a catalyst material which consists of a catalyst support and a catalytically active material mounted on the catalyst support, wherein the catalyst support is preferably alumina (Al ₂ O ₃ ) or zirconium oxide (ZrO ₂ ) and in the catalytically active material is preferably nickel, rhodium or ruthenium.

By The invention can be a carbon monoxide rich synthesis gas with essential lower fuel demand and residual methane content are produced, as is possible in the prior art. Furthermore can the investment needs for the separation of carbon dioxide be significantly reduced. Because of the possible high Synthesis gas pressure can be saved intermediate compressor and wire cross sections are reduced.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10320965 A [0022]
• - DE 102005026881 A [0023]
• - DE 10332860 A [0024]

Claims (15)

Process for the production of a carbon monoxide-rich, low-methane gas (synthesis gas), wherein a hydrocarbon-containing feed (fuel) is reacted together with carbon dioxide (CO ₂ ) and / or water vapor and an oxidizing agent by catalytically assisted partial oxidation (ATR), characterized in that the synthesis gas is recovered as a product gas of the autothermal reforming at a temperature of more than 1100 ° C. Method according to claim 1, characterized in that that the syngas is generated at a temperature between 1100 and 1400, preferably between 1100 and 1250, and more preferably between 1130 and 1200 ° C. Method according to one of claims 1 or 2, characterized in that the synthesis gas with a pressure which is between 1 and 100, preferably between 5 and 80 and more preferably between 10 and 40 bar (a). Method according to one of claims 1 to 3, characterized in that for the reforming step, a catalyst is used which consists of a catalyst support and a catalyst supported on the carrier, catalytically active material, wherein the catalyst support is preferably alumina (Al ₂ O ₃ ) or zirconium oxide (ZrO ₂ ) and in the catalytically active material is preferably nickel, rhodium or ruthenium. Method according to one of claims 1 to 4, characterized in that the fuel water vapor in a Amount is mixed, so that the ratio of water vapor and the carbon bonded in the hydrocarbons (D / C ratio) between 0 and 2, preferably between 0.1 and 1.0, and more preferably is between 0.2 and 0.6 mol / mol. Method according to one of claims 1 to 5, characterized in that the fuel carbon dioxide in an amount is mixed, so that the ratio of carbon dioxide and the bound carbon in the hydrocarbons (CO ₂ / C ratio) between 0 and 3, preferably between 0.5 and 2.0 and more preferably between 0.6 and 1.0 mol / mol. Method according to one of claims 1 to 6, characterized in that the fuel is added via an oxidizing agent oxygen in an amount such that the ratio of oxygen and the carbon bonded in the hydrocarbons (O ₂ / C ratio) is between 0.5 and 0.9, and preferably between 0.55 and 0.8 mol / mol. An apparatus for producing a low carbon, low methane gas (synthesis gas), comprising a refractory lined, pressure-resistant reactor (ATR reactor) in which a hydrocarbon-containing feed (fuel) together with carbon dioxide (CO ₂ ) and / or water vapor and a Oxidizing agent by catalytically assisted partial oxidation (autothermal reforming or ATR) can be implemented and a reactor burner, via which the starting materials in the reaction chamber of the ATR reactor can be introduced, characterized in that the synthesis gas as a product gas from the ATR reactor at a temperature of more than 1100 ° C is deductible. Device according to claim 8, characterized in that that the ATR reactor formed as a vertical tubular reactor is, wherein the cylindrical reaction space with a ratio from length to diameter between 7 and 16, preferably however, is executed between 9 and 14. Device according to claim 8, characterized in that that the combustion chamber of the ATR reactor as a vertical tubular reactor is formed, wherein the cylindrical reaction space with a ratio from length to diameter between 7 and 16, preferably however, is executed between 9 and 14. Device according to one of claims 8 or 9, characterized in that the reactor burner as gas-cooled Burner is executed. Device according to one of claims 8 to 10, characterized in that the reactor burner as a swirl burner is executed. Device according to one of claims 8 to 11, characterized in that the refractory lining of the ATR reactor is at least bivalve, the outer shell composed of molded parts is, which consist of fiber material. Apparatus according to claim 12, characterized in that the inner, the reaction space forming shell of the refractory lining of dry set ZrO ₂ -Steinen is constructed. Device according to one of claims 8 to 13, characterized in that the ATR reactor contains a catalyst material consisting of a catalyst support and a catalyst supported on the catalytically active material, wherein it is in front of the catalyst support Preferably, aluminum oxide (Al ₂ O 3) or zirconium oxide (ZrO ₂ ) and in the catalytically active material is preferably nickel, rhodium or ruthenium.