DE102008039014A1 - Multi-stage reactor cascade for soot-free production of systhesegas - Google Patents

Abstract

A method and apparatus for soot-free production of synthesis gas from hydrocarbonaceous feed gas and oxygen-containing gas in a multi-stage cascade comprising at least one of catalytic autothermal reforming and / or catalytic partial oxidation, wherein each stage of the cascade is supplied with oxygen-containing gas and hydrocarbon feed gas, respectively converted to hydrogen-containing process gas and goes through in series the entire subsequent cascade. Alternatively, it is a two-stage series circuit comprising in the first stage an allothermal steam methane reformer, and in the second stage a catalytic autothermal reformer, wherein the second stage, the hydrogen-containing process gas of the first stage is fed and additionally hydrocarbon feed gas, steam and oxygen-containing gas is supplied, wherein the balanceable H2 stream of a preceding stage with respect to the stoichiometry of H2O formation of the next stage preferably compensates for the O2 requirement of this subsequent stage, but at most equal to twice the amount of balance size, and the hydrocarbon-containing feed gas and the oxygen-containing gas separated from each other via devices that protrude at different levels with different orientation in the last catalytic autothermal reforming stage, wherein the oxygen-containing gas via at least one separate feeder ...

Description

The invention relates to a process for the large-scale production of synthesis gases for ammonia, Fischer-Tropsch, methanol or other syntheses by means of a multi-stage reactor cascade, which allows to work with a low steam-to-carbon ratio without it to damage the catalysts by soot formation comes. The cascade comprises at least one of the stages catalytic autothermal reforming and / or catalytic partial oxidation, wherein each stage of the cascade oxygen-containing gas and hydrocarbon feed gas is supplied, which is converted to hydrogen-containing process gas and in series through the entire subsequent cascade. Alternatively, the cascade comprises a two-stage series circuit comprising in the first stage an allothermal steam methane reformer, and in the second stage a catalytic autothermal reformer, wherein the second stage, the hydrogen-containing process gas of the first stage is fed and additionally hydrocarbon feed gas, steam and oxygen-containing Gas is supplied, wherein the balanceable H ₂ stream of a preceding stage with respect to the stoichiometry of H ₂ O formation of the next stage preferably compensates the O ₂ requirement of this subsequent stage, but at most equal to twice the amount of balance size, and the hydrocarbon-containing feed gas and the oxygen-containing gas is supplied separately from one another via devices which protrude at different levels with different orientation in the last catalytic autothermal reforming stage, wherein the oxygen-containing gas via at least one separate feed secant to the M Is introduced the first point of the circular reactor above the catalyst bed, and the hydrocarbon-containing feed gas is preferably fed axially at the top of the reactor. The invention also relates to the respective device for carrying out such a method.

A Possibility to produce synthesis gas from natural gas the use of steam methane reformers. These are kilns, in which catalyst-filled tubes systematically are arranged. The for the endothermic reforming reaction needed heat is through burners in the ovens generated.

A another way to synthesis gas production, in the on an external heat supply can be dispensed with can, based on the autothermal cleavage of the hydrocarbon Feed gas with oxygen-containing gas and steam in an autothermal Reformer. These are catalytic reactors that heat the exothermic hydrocarbon combustion for the subsequent use endothermic reforming reaction, so that both reactions drain in a single compact reactor.

disadvantage said embodiments, the risk of soot formation under certain conditions, detailed below will be received. As the cause of soot formation can in the partial combustion of hydrocarbon-containing feed gas among other things a local lack of oxygen responsible made a pyrolysis of the hydrocarbons and thus results in the formation of soot. So-called soot precursors such as acetylene must be degraded in the catalyst bed with steam become.

• CH₄ + H₂O ⇔ CO + 3H₂ (1)
• C_nH_2n+2 + nH₂O ⇔ nCO + (2n + 1)H₂ (2)
• CO + H₂O ⇔ CO₂ + H₂ (3)
• H₂O + C ⇔ CO + H₂ (4)

The catalytic autothermal reforming can in principle be divided into 2 stages. On the one hand, this is a combustion chamber for producing a high-temperature feed gas by substoichiometric, partial combustion of a hydrocarbon-containing feed gas with an oxygen-containing gas and, on the other hand, a catalyst-filled reaction zone in which unbeaten hydrocarbons are simultaneously split with H ₂ O under adiabatic process conditions. In addition, a CO conversion with H ₂ O takes place:

• CH ₄ + H ₂ O⇔CO + 3H ₂ (1)
• C _n H _{2n + 2} + nH ₂ O ⇔nCO + (2n + 1) H ₂ (2)
• CO + H ₂ O⇔CO ₂ + H ₂ (3)
• H ₂ O + C⇔CO + H ₂ (4)

there the output temperature of the reformer stage is in the range between 800 ° C and 1025 ° C.

H ₂ O in the reactions (1) to (4) mentioned on the one hand has the function that it serves as a reactant for the cleavage of CH ₄ and higher hydrocarbons in the catalyst zone and further it serves according to equation (4) as a moderator to prevent the soot formation in the catalyst bed.

An increased H ₂ O feed could now be used to minimize soot, but is the oxygen demand for the partial combustion is very much dependent on the steam to hydrocarbon ratio of the feed gas mixture. In order to keep the O ₂ requirement and thus the investment costs low, one strives to minimize the H ₂ O content in the feed gas, which also has the advantage of shifting the reaction equilibrium on the part of the CO component.

• CH₄ + 0,5O₂ ⇒ CO + 2H₂ (5)

An alternative to autothermal reforming is provided by the catalytic partial oxidation of methane, which also undergoes a catalytic autothermal process, also known as cPOX. In this case, a hydrocarbon-containing feed gas and oxygen-containing gas is added directly to a catalyst, on which the partial combustion at low temperatures, such as at 850 ° C, takes place. Ideally, this is done in the absence of steam, ie at a zero vapor to carbon ratio. Under these conditions, the reaction mechanism dominates the so-called oxy reforming, which proceeds according to the following reaction equation:

• CH ₄ + 0.5 O ₂ ⇒ CO + 2H ₂ (5)

• • In K. Heitnes et al, Catalysis Today 24 (1995) 211–216, Elsevier Science B. V. und in E. H. M. Vermeiren et al, Catalysis Today 13 (1992) 427–436, Elesevier Science B. V. wird die Totalverbrennung eines Teils des CH₄ unter H₂O-Bildung mit nachfolgender endothermer Reformierungsreaktion des nicht umgesetzten CH₄ nach Gleichung (1) und Gleichung (3) beschrieben.
• • In Rongchao Jin et al, Applied Catalysis A: General 201 (2000) 71–80, Elesivier Science B. V. , wird für Ni/Al₂O₃ Katalysatoren das Modell der ”Direkten partiellen Oxidation” vorgestellt. Dabei erfolgt nach einer Aktivierungsphase mit Temperaturanstieg unter Bildung von Metalloxid (NiO) und Verbrennung von CH₄ über dem gebildeten Metalloxid eine teilweise endotherme Reduzierung des Metalloxids durch nicht umgesetztes CH₄(NiO → Ni/NiO). Über den frei werdenden Ni-Oberflächen erfolgt eine CH₄-Dissoziation mit H₂-Abspaltung und Bildung von Kohlenstoffdeckschichten (CH₄ + Ni → NiC + 2H₂). Die Bildung des CO erfolgt über eine Interaktion der aktiven Zentren des NiO und des NiC. Der letzte Reaktionsschritt verläuft dabei nahezu isotherm.

Laboratory studies for the interpretation of the oxy reforming were carried out both with expensive noble metal catalysts, as well as with cheaper Ni-based catalysts. There are two models for the interpretation of the reaction mechanism:

• • In K. Heitnes et al., Catalysis Today 24 (1995) 211-216, Elsevier Science BV and in EHM Vermeiren et al, Catalysis Today 13 (1992) 427-436, Elesevier Science BV the total combustion of a portion of the CH ₄ under H ₂ O formation with subsequent endothermic reforming reaction of the unreacted CH ₄ according to equation (1) and equation (3) is described.
• • In Rongchao Jin et al, Applied Catalysis A: General 201 (2000) 71-80, Elesivier Science BV , the model of "direct partial oxidation" is presented for Ni / Al ₂ O ₃ catalysts. In this case, after an activation phase with temperature rise to form metal oxide (NiO) and combustion of CH ₄ over the metal oxide formed, a partial endothermic reduction of the metal oxide by unreacted CH ₄ (NiO → Ni / NiO). Over the liberated Ni surfaces occurs a CH ₄ dissociation with H ₂ splitting and formation of carbon topcoats (CH ₄ + Ni → NiC + 2H ₂ ). The formation of CO occurs via an interaction of the active sites of NiO and NiC. The last reaction step is almost isothermal.

The Advantages of the process lie in the compact construction and the low oxygen demand of the oxy reforming. For the realization However, there are a number of catalytic partial oxidation Litigation risks. In addition to "hot spots" in the catalyst structure stands the long-term stability of the catalysts under the Aspect of the carbon topcoat for debate. For large-scale The benchmarks will be the catalytic autothermal reforming for the time being the dominant technology.

Of the The prior art proposes various possible solutions to prevent soot formation in a catalytic autothermem To minimize reformers.

In DE 10230149 A1 is z. For example, it is described that soot formation occurs below a soot formation limit at readings of λ = 0.6, where λ is the air ratio and λ = 1.0 corresponds to stoichiometric combustion, assuming atmospheric CH ₄ combustion. These results are based on experiments with intensive mixing of air and fuel gas in the burning zone. The above value can be further lowered by using pure O ₂ as the adiabatic temperature increases and thus the burning rate is increased.

This shows that the combustion temperature in the burner significantly influences soot formation. Accordingly, the temperature distribution in the flame should have no local minima. In DE 10230149 A1 However, test results are cited that show an increased soot formation with lowering of the flame temperature by additional cooling in the surface jet burner. The explanation of these effects on the combustion rate is insufficient under the conditions of substoichiometric combustion (λ <1), since in the case of soot formation, the carbon of the feed gas is not completely burned, but the oxygen is consumed. The combustion of hydrocarbons proceeds, as mentioned above, via the formation of soot precursors such as acetylene ( J. Warnatz, Ber. Bunsenges. Phys. Chem. 87 (1983) 1008-1022 ). Accordingly, at lower temperatures, different rates of combustion of the intermediates should also be considered, which are generated in a chain of secondary reactions. One of the first fission products of this chain is hydrogen, which burns very quickly, so that it can not be ruled out that most of the stoichiometric unbalanced hydrocarbons are present as carbon black precursors and H ₂ O at the end of the process. This one speaks then of a Se selective combustion of hydrogen at low temperatures.

In diffused flame burners, either a pronounced pyrolysis occurs in the O ₂ -marm zone in the center of the flame or in the O ₂ -free zone beyond the flame. In the latter, the risk of soot formation is particularly high, since the hot zones beyond the burnout receive no oxygen, but are subject to intensive pyrolysis at high temperatures. The intensity of soot formation is dependent on the height of the flame temperature as well as on the surface of the burn-out zone of the flame.

In the case of catalytic autothermal reforming, the use of highly turbulent swirl burners is customary, which represent a special embodiment of the diffusion flame, and produce the most ideal possible mixing of O ₂ and fuel at the outlet of the burner. But even in the cold start-up phase and with feed gases containing higher hydrocarbons, these burners are not ideal. In EP 0989094 B1 It is proposed to convert higher hydrocarbons by adding a pre-reformer with H ₂ O to CH ₄ , CO and H ₂ , which in turn involves very high costs.

at low temperatures find those described in (1) to (3) Equilibrium reactions that compensate for pyrolysis, only limited and thus there is, inter alia, to increased acetylene formation. The reaction chain begins according to the following scheme:

• CH ₄ ⇔ CH ₃ + H (6a)
• 2CH ₃ ⇔ C ₂ H ₅ + H (6b)
• 2CH ₃ ⇒ C ₂ H ₄ + H ₂ (6c)

From the literature it is known that H ₂ burns much faster than other gases.

Table 1 shows the comparison of the maximum (v _max ) and stoichiometric (v _stoe ) combustion _{rates of} different combustion gases with cold air (293.15 K, 1.013 bar). fuel gas V _max [cm / sec] V _stoe [cm / sec] literature source H ₂ 346 237 C. -J. Winter, et al. Springer-Verlag 1989 CH ₄ 43 42 C. -J. Winter, et al. Springer-Verlag 1989 C ₂ H ₄ 22 (interpolated) V. Kah, V. Edition, Chemistry Leuna AG C ₂ H ₂ 85 (interpolated) V. Kah, V. Edition, Chemistry Leuna AG

The interpretation of these points leads to the conclusion that a feed of external H ₂ into the combustion chamber leads to the suppression of the CH ₄ cleavage and the acetylene formation and that the additional H _{2 introduced is} largely converted to H ₂ O due to the relatively high combustion rate. This is in the US 6,818,198 B2 implemented so that by recirculation of hot H ₂ - and H ₂ O-rich synthesis gas, a reduction of the steam-to-carbon ratio is aimed at, without resulting in increased acetylene.

• CH₄ + Ni° ⇒ Ni...C + 4H (7)

wobei Ni° als reduziertes feindispergiertes metallisches Ni und Ni...C als Kohlenstoffdeckschicht auf der Ni-Oberfläche verstanden wird ( R. Jin et al., Applied Catalysis A: General 201 (2000), 71–80, Elsevier Science B. V. ).Commercially available steam methane reformers are based on NiO / Al ₂ O ₃ catalysts. Here, CH ₄ dissociates via reduced NiO at temperatures above 390 ° C and absence of H ₂ O according to:

• CH ₄ + Ni ° ⇒ Ni ... C + 4H (7)

where Ni ° is understood as a reduced finely dispersed metallic Ni and Ni... C as a carbon coating layer on the Ni surface ( R. Jin et al., Applied Catalysis A: General 201 (2000), 71-80, Elsevier Science BV ).

At elevated steam to hydrocarbon ratio, the hydrocarbon is reacted according to equation (4) at the phase boundary without damaging the catalyst. Therefore, it is common in steam methane reformers in practice to prevent soot formation by admixing H ₂ O to the hydrocarbon-containing feed gas.

Calculating the stoichiometric combustion of CH ₄ and H ₂ under ambient conditions with air, the H ₂ balance will yield higher adiabatic temperatures than the CH ₄ balance:
Table 2 shows the result of stoichiometric combustion calculations with cold air (20 ° C) and fuel gas (200 ° C) at 1.013 bar. gas Invoice 1 Invoice 2 Invoice 3 Invoice 4 CH ₄ [mol%] 100 25 H ₂ [mol%] 100 25 H ₂ O [mol%] 75 75 T adiabatic ° C 2053 2289 1646 1228

These However, values only apply to the combustion of the individual components.

Taking into account an inert gas such. B. H ₂ O vapor, reverse conditions apply. This effect is based on the calorific balance of the gas mixtures, ie, taking into account an inert gas, the specific heat capacities of the feed and the fuel gas change and thereby cause a significantly corrected adiabatic temperature jump.

From the previous points it can be concluded that an additional H ₂ supply into a CH ₄ flame has this cooling effect. The risk of additional soot formation does not exist because the lowering of the flame temperature is due to a change in the consistency of the fuel. As a result of this effect, at a given adiabatic combustion temperature, which is dependent on the design temperature of the catalyst, an increase in the O ₂ feed into the combustion chamber, whereby the CH ₄ conversion increases due to additional combustion, can indirectly increase the exit temperature from the catalyst bed. by reducing the CH ₄ conversion by reforming, which also leads to an increase in the distance to the Boudouard equilibrium.

This one makes oneself in the EP 1604948 A1 exploiting, by recirculation of H ₂ - and CO-rich synthesis gas, a lowering of the flame temperature is achieved in the combustion chamber in order to achieve a favorable reaction equilibrium at high catalyst outlet temperatures without thermal damage to the catalyst. In particular, care must be taken that the supplied hydrogen is intensively premixed with the fuel gas.

The supply of H ₂ into the combustion zone of a swirl burner of a catalytic autothermal reformer initially has a cooling effect on the flame and thus on the inlet temperature in the catalyst zone. As a result, in accordance with the design temperature of the catalyst, additional adiabatic catalyst exit temperature can be increased by additional O ₂ feed, which reduces the risk of carbon deposition in the catalyst bed. This procedure is particularly suitable when CO-rich synthesis gases under high catalyst outlet temperatures, such as. As in the Fischer-Tropsch synthesis to be produced. In compensation of this effect, the steam to hydrocarbon ratio and thus the O ₂ supply can be reduced.

When using O ₂ -Brennerlanzen for O ₂ entry, the cooling of the flame brings a lower heat radiation in the zone beyond the burn with it, thus reducing the risk of intense pyrolysis associated with the formation of soot. In this case, an increase in the adiabatic temperature in the combustion chamber due to additional O ₂ supply causes less an increase in the flame temperature, but rather an increase in the flame. Thus, the extent of soot formation can be achieved by choosing a lower autothermal exit temperature and higher steam to hydrocarbon ratio. This method is therefore suitable for the production of H ₂ rich synthesis gas.

To reduce the pollutants and to save energy, a steam methane reformer is combined with a downstream catalytic autothermal reformer in the prior art. An exemplary development of this method is in the EP 0233076 B1 described. Here, a partial stream of the hydrocarbon-containing feed gas is conducted past the steam methane reformer to be fed directly to the subsequent catalytic autothermal reformer. The aim of this circuit is the generation of a synthesis gas with a defined stoichiometric indicator for the methanol synthesis. However, if the feed gas contains higher hydrocarbons, additional steam must be introduced into the steam methane reformer for splitting, which leads to an increase in the plant. This problem solves the problem DE 10 2006 023 248 A1 by dividing the feed gas into a pre-reformer before splitting it into two sub-streams passes through it comes to the cleavage of higher hydrocarbons.

In the EP 1927577 A1 will the circuit of EP 0233076 B1 insofar further developed as the gas stream which is fed to the catalytic autothermal reformer in addition to the product stream from the steam-methane reformer, which is mixed with a partial stream of the hydrocarbon-containing feed gas, nor a partial stream of the synthesis gas from the catalytic autothermal reforming is fed by recycling , This ensures that there is a reduction of soot formation in the catalytic autothermal reformer.

In GB 2407819 A Synthesis gas production is being solved by combining three different types of reformers with the aim of achieving higher plant capacities. In this case, an adiabatic pre-reformer is arranged in series with a steam methane reformer and an autothermal or POX reformer, the latter being arranged parallel to one another.

There with the above-mentioned solution attempts, the soot minimization and simultaneously minimizing the steam to hydrocarbon ratio, no ideal solutions to the problem can be achieved There is still a need for improvements the existing processes and plants further optimize the Effect reforming reaction in syngas production what makes the invention to be described here the task. It is the object of the invention both a method for solution the described task, as well as a device for carrying out of the method.

These Task is with a method for soot-free production of synthesis gas from hydrocarbon-containing feed gas and oxygen-containing Gas in a multistage cascade, which is at least one of the stages catalytic autothermal reforming and / or catalytic partial Having oxidation, wherein each stage of the cascade is oxygen-containing Gas and hydrocarbon feed gas supplied which is converted in each case to hydrogen-containing process gas and in series the entire subsequent cascade goes through.

• 2H₂ + O₂ ⇒ 2H₂O (8)

In one embodiment of the method, the H ₂ flow that can be balanced in a preceding stage, with reference to the stoichiometry of the H ₂ O formation of the subsequent stage, preferably compensates for the O ₂ requirement of this succeeding stage, but at most the H ₂ flow that can be balanced is 1.5 times Amount of balance sheet size. This procedure is based on the following equation:

• 2H ₂ + O ₂ ⇒ 2H ₂ O (8)

In a further embodiment of the method becomes the first reforming stage of the cascade, called catalytic Autothermal reforming is carried out at a higher Steam-to-carbon ratio realized as in the Follow-up stages of the cascade. The vapor-to-carbon ratio is this Reforming stage in a range between 1.0 and 3.0.

optional In the first stage of the reaction of the cascade a catalytic reaction takes place partial oxidation from.

optional is the individual in the process according to the invention Steps of the cascade additionally supplied steam. This step may be useful in performing a catalytic partial oxidation omitted.

A further possibility of the process design lies in that the hydrocarbon-containing feed gas before passing through a catalytic reactor stage together with steam a pre-reforming step to undergo. Alternatively, only the hydrocarbon-containing Feed gas before passing through the first catalytic reactor stage be subjected to a pre-reforming step together with steam.

Furthermore, the above-described problems arising from the prior art are solved by a method for the soot-free production of synthesis gas from a hydrocarbon-containing feed gas and from oxygen-containing gas and water vapor in a two-stage series circuit comprising an allothermal steam in the first stage Methane reformer, and in the second stage, a catalytic autothermal reformer, wherein the second stage, the hydrogen-containing process gas of the first stage is fed and in addition hydrocarbon feed gas, steam and oxygen-containing gas is supplied, is used. This method is characterized in particular by the fact that the H ₂ flow of a preceding stage, which can be balanced, with respect to the stoichiometry of the H ₂ O formation of the subsequent stage preferably compensates for the O ₂ requirement of this subsequent stage, but at most 2 times the amount of Bi lanzgröße and the hydrocarbon-containing feed gas and the oxygen-containing gas separately via devices which protrude at different levels with different orientation in the last catalytic autothermal reforming stage, wherein the oxygen-containing gas via at least one separate feed secantially to the center of the circular reactor above the Catalyst bed is introduced, and the hydrocarbon-containing feed gas is preferably fed axially at the top of the reactor.

Further advantageous embodiments of this two-stage process relate to the feed of the process gas from the steam methane reformer in the catalytic autothermal reformer. This can for one thing happen that the process gas from the steam methane reformer with hydrocarbon-containing feed gas is mixed and this mixture is fed axially at the top of the reactor. On the other hand exists the possibility of the process gas from the steam methane reformer to mix with hydrocarbon-containing feed gas and this Mixture via at least one separate feed secantially to the center of the circular reactor to introduce the catalyst bed in the catalytic autothermal reformer. Another option is the process gas from the steam methane reformer without prior admixture with the hydrocarbon feed gas over at least one separate feeder secantial to the center of the circular reactor above the catalyst bed to introduce in the catalytic autothermal reformer.

In a further embodiment of the invention Two-stage process takes place in the catalytic autothermal Reformierungsstufe an additional separate oxygen supply, with which a pilot burner is operated.

In One embodiment of the two-stage process is in the steam methane reformer a hydrocarbon-containing feed gas and water vapor at a Ratio of steam to carbon, calculated as a ratio from moles of steam to moles of pure carbon in the hydrocarbon, from 2.0 to 4.0, preferably from 2.8, allothermic reacted.

Of Further, in the two-stage invention Process in the catalytic autothermal reforming stage hydrocarbon-containing feed gas and an oxygen-containing Gas and water vapor at a steam to carbon ratio, calculated as the ratio of molar amount of steam to molar amount pure carbon in the hydrocarbon, from 0.0 to 3.0, implemented become.

In a further embodiment of the two-stage process is the hydrocarbon-containing feed gas of the catalytic autothermal Reforming stage together with steam before going through this reforming stage heated in a pre-reformer.

A Another embodiment of the two-stage process it is the steam methane reformer a partial flow consisting of at least 10%, preferably 25% based on the hydrocarbon-containing Feed gas of both stages to feed.

The corresponding device for carrying out the soot-free Production of synthesis gas in a multi-stage reformer cascade, comprising at least two catalytic reactor stages, a device for the introduction of the hydrocarbon-containing feed gas in the first catalytic reactor stage, an apparatus for introduction from oxygen-containing gas to the first catalytic reactor stage, and a device for transferring the in one Reactor stage received process gas in a subsequent reactor stage, the catalytic reactors via the process gas guide are connected in series, a device for supplying oxygen-containing gas in the individual series-connected catalytic Reactors is provided, and devices for feeding of hydrocarbon-containing feed gas in the process gas guide and / or provided in the individual series-connected catalytic reactors are.

A Possibility of designing the device relates to reactors provided in the cascade. The cascade can be exclusive consist of catalytic autothermal reformers or alternatively can the first stage of the cascade by means of a catalytic partial oxidation element will be realized.

optional The device according to the invention can be designed in this way be that inlet for the hydrocarbon Feed gas of a catalytic reactor with the outlet of the gas connected to a pre-reformer. Alternatively, this interconnection with a pre-reformer just for the first catalytic Reactor of the cascade apply.

The corresponding device for carrying out the soot-free Production of synthesis gas in a two-stage reformer cascade, comprising a steam methane reformer, a catalytic autothermal reformer, a device for introducing the hydrocarbon-containing feed gas, in the steam methane reformer, a device for the initiation of Water vapor in the feed gas device, and a device for transfer of the process gas obtained in the steam methane reformer in the catalytic Autothermal reformer, wherein in each case at least one device for gas entry at the reactor head of the catalytic autothermal reformer is provided, and other devices for gas entry, the secantial to the center of the circular reactor are aligned and different at different levels Orientation to the container center axis protrude into the reactor. In this case, the devices for gas entry, for example Be lances.

A Another possibility of the design of the two-stage Reformer cascade is a device for mixing the process gas the respective reformer with hydrocarbon-containing feed gas provided.

In Another embodiment of the two-stage reformer cascade is an additional separate feeder for oxygen-containing gas at the reactor head of the last catalytic Autothermal reformer stage provided with a pilot burner connected is.

In an embodiment of the invention two-stage Reformer cascade becomes the inlet for the hydrocarbon Feed gas of the catalytic autothermal reformer with the outlet connected to the gas of a pre-reformer.

The The invention will be described in more detail below by way of example with reference to FIG. 6 explains:

1 A method according to the invention for the soot-free production of synthesis gas by means of a multistage cascade of catalytic reactors.

2 : An inventive embodiment of the inventive method for soot-free production of synthesis gas by means of a multi-stage cascade of catalytic autothermal reformers, which is preceded by a pre-reformer.

3 : A process sketch for the soot-free production of synthesis gas, in which the cascade consists of a series arrangement of a reactor for catalytic partial oxidation and a catalytic autothermal reformer with upstream pre-reformer by way of example.

4 : A process flow diagram of a two-stage series circuit comprising in the first stage an allothermal steam methane reformer, and in the second stage a catalytic autothermal reformer, which is preceded by a pre-reformer.

5 : Cross section of a catalytic autothermal reformer, as in the two-stage series circuit 4 is to be used, with arrangement examples of the lances with respect to the circular reactor.

6 : Longitudinal section of a catalytic autothermal reformer, as in the two-stage series circuit 4 is to be used, with arrangement examples of the lances with respect to the different levels and the different orientations to the container center axis of the reactor.

1 shows a cascade containing by way of example four catalytic reactors 1a . 1b . 1c . 1d that about the process gas guidance 5a . 5b . 5c are connected in series. All are catalytic reactors 1a . 1b . 1c . 1d with feed lines for hydrocarbon-containing feed gas 4b . 4c . 4d . 4e , oxygen-containing gas 2a . 2 B . 2c . 2d and optional for steam 3a . 3b . 3c . 3d fitted. If one of the catalytic reactors is designed as a catalytic partial oxidation element, the steam supply can be dispensed with. The hydrocarbon-containing feed gas 4b , which is the first catalytic reactor 1a goes through there is optional by means of steam 3a and oxygen-containing gas 2a in a process gas 5a implemented that via a conduit into the second catalytic reactor 1b by passing it with the hydrocarbon feed gas 4c is mixed. Optionally, the feed gas mixture thus obtained 6a continue with steam 3b be enriched. That in the process stage 1b recovered process gas 5b then enters the hydrocarbon feed gas 4d passed and gives the feed gas mixture 6b , in turn, with steam 3c can be enriched and then into the third catalytic reactor 1c is directed. There is the process gas 5c generated that with the hydrocarbon-containing feed gas 4e is mixed and the feed gas mixture 6c that forms with steam 3d can be enriched and through the subsequent reactor 1d is sent. The cascade can be continued until a synthesis gas 9 obtained with desired properties and quality. The final product can be used, for example, for ammonia or methanol production.

In practice, the implementation of the feed gas 4a hydrocarbons contained primarily in an initial catalytic autothermal reactor. The subsequent reactors are then mainly used to optimize the quality of the recovered synthesis gas 9 ,

2 differs from 1 in that the cascade two catalytic autothermal reformer 7a . 7b includes and additionally the inlets for the hydrocarbonaceous feed gas of the catalytic autothermal reformer 7a . 7b with the outlet of the gas of a pre-reformer 8th are connected. This may be necessary when higher hydrocarbons have to be split. It is in the in 2 embodiment shown the hydrocarbon-containing feed gas 4f steam 3e fed and both gases are used as a mixture in the pre-reformer 8a directed. After passing through the pre-reformer 8a becomes the resulting hydrocarbonaceous feed gas 4g divided. The first partial flow 4h becomes steam 3f added and the mixture passes through the first catalytic autothermal reformer 7a , which has a separate supply line for oxygen-containing gas 2e features. The first catalytic autothermal reformer 7a leaving process gas 5d becomes the hydrocarbon-containing feed gas 4g that the pre-reformer 8a has passed through, fed and as feed gas mixture 6d in the second catalytic autothermal reformer 7b directed. Also this one is with a separate supply line for oxygen-containing gas 2f fitted. Optionally, it can be used to add steam 3g come.

In the embodiment in 2 For example, the process is carried out in such a way that in the first catalytic autothermal reformer 7a a hydrocarbon-containing feed gas 4h and an oxygen-containing gas 2e and steam 3f at a ratio of steam to carbon, calculated as the ratio of moles of steam to moles of pure carbon in the hydrocarbon, from 1.3 to 3.0. In contrast, in the subsequent catalytic autothermal reformer 7b but at least in the last catalytic autothermal reformer of a reformer cascade a hydrocarbon-containing feed gas 6d and an oxygen-containing gas 2f and steam at a ratio of steam to carbon, calculated as the ratio of moles of steam to moles of pure carbon in the hydrocarbon, from 0.0 to 2.5.

In the embodiment in FIG 3 becomes the first catalytic autothermal reformer 7a out 2 through a catalytic partial oxidation reactor 10 replaced. The hydrocarbon-containing feed gas 4i is shared and a first partial flow 4y gets steamed 3h staggered and goes through a pre-reformer 8b , The second partial flow 4k enters the reactor for catalytic partial oxidation 10 and is only optional with steam 3i added. Otherwise, the reactor becomes 10 operated at zero at a steam to carbon ratio. The process gas generated in the catalytic partial oxidation 5e is before passing through the catalytic autothermal reformer 7c from the pre-reformer 8b coming hydrocarbon feed gas 4l added. This feed gas mixture 6e then goes through the second catalytic autothermal reformer 7c , Again, this reforming stage can optionally steam as needed 3y be supplied. Both reformers of the cascade have separate supply lines for oxygen-containing gas 2g . 2h ,

Used in the reformer for catalytic partial oxidation 10 used a suitable catalyst material, the step of pre-reforming can be omitted in a pre-reformer.

For example, a small partial flow of the hydrocarbon-containing feed gas should be supplied in carrying out the respective preceding stage, which in all embodiments in 1 to 3 at least 10%, but preferably 25% based on the total process gas. The operating pressure of the reforming stages is set in the implementation of the process between 20 and 60 bar. By way of example, the outlet temperature of the first catalytic reactor stage 10 in 3 set at 850 ° C and operated without steam, while the outlet temperature of the catalytic autothermal reformer 7c of the embodiment is set to a temperature around 900 ° C. In addition, technically pure oxygen is used as the oxygen-containing gas.

4 represents a two-stage cascade of steam methane reformer 11 and catalytic autothermal reformer 7d This is the hydrocarbon-containing feed gas 4m with steam 3k mixed and a partial stream of this steam / feed gas mixture 12a goes through the steam methane reformer 11 to which additionally separately steam 3l can be forwarded. The second part of the feed gas-steam mixture 12b goes through a pre-reformer 8c , The process gas flow 5f in the steam methane reformer 11 is obtained is split so that a first partial flow 5g into the hydrocarbon-containing feed gas 4n that the pre-reformer 8c has passed through, is passed and a feed gas mixture 6e forms while a second partial flow 5h the process gas from the steam methane reformer 11 directly in the subsequent catalytic autothermal reformer 7d secantial to the center of the circular reactor 7d is introduced above the catalyst bed. The feed gas mixture 6e is also split to a first partial flow 6f at the reactor head of the catalytic autothermal reformer 7d axially introduce and a second partial flow 6g via at least one feed secantially to the center of the circular reactor 7d above the catalyst bed. The supply lines for the oxygen-containing gas 2i of the catalytic autothermal reformer 7d allow also a contribution of the gas, the secantial to the center of the circular reactor 7d takes place over the catalyst bed.

5 forms a cross section of a catalytic autothermal reformer 7d off, as in the second-stage series circuit 4 containing a steam methane reformer and a catalytic autothermal reformer to be used. In this case, various embodiments of the lance arrangements for the supply of hydrocarbon-containing feed gas and / or process gas and oxygen-containing gas are shown. In this case, the left embodiment provides two lances 13a . 13b to the semantic entry related to the center 16 of the circular reactor 7d of oxygen-containing gas over the catalyst bed. This type of introduction of the oxygen-containing gas may be accompanied by the supply of the feed and / or process gas 14a . 14b be combined so that the lances 13a and 14a , such as 13b and 14b are arranged crosswise, as shown in the middle graph. Another embodiment is shown in the right figure. Here are all lances 13a . 13b . 14a . 14b equidistant from each other in the catalytic autothermal reformer 7d introduced. The alignment of the lances 13 . 14 can be related to the midpoint 16 of the circular reactor, including the two extreme orientations from tangential to a 90 ° angle, have all the angular dimensions therebetween, which is then referred to as secantial. These options can be used to create swirl impulses in a targeted manner, thus minimizing the generation of soot.

In 6 is a longitudinal section of the catalytic autothermal reformer 7d out 4 shown. Here it becomes clear that the lances 15a . 15b may be attached to the gas inlet at different levels on the reactor wall. In addition, the figure shows that the lances 15a . 15b different orientations to the container center axis 17 of the reactor 7d can have. In this embodiment, the lance shows 15a a 90 ° angle to the container center axis 17 of the reactor and the lance 15b has an acute angle to the container central axis 17 of the reactor 7b on. In this case, the lances should preferably be oriented downwards toward the catalyst bed, so that the acute angle of the lance alignment to the container axis moves between 90 ° and 45 °.

• • Minimierung der Rußbildung, womit eine verlängerte Betriebszeit der Katalysatorenbetten erreicht wird.
• • Minimierung der Dampf-zu-Kohlenwasserstoff-Verhältnisse bei der Reformierung, was mit einem reduzierten O₂-Verbrauch verknüpft ist.
• • geringere Investitionskosten

Advantages resulting from the invention:

• • Minimization of soot formation, thus achieving extended catalyst bed service life.
• • Minimization of steam to hydrocarbon ratios in reforming, which is associated with reduced O ₂ consumption.
• • lower investment costs

1a, 1b, 1c, 1d

catalytic reactor

2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i

oxygenated gas

3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, 3l, 3m

steam

4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4j, 4k, 4l, 4n, 4n

hydrocarbonaceous feed gas

5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h

process gas

6a, 6b, 6c, 6d, 6e, 6f, 6g

Feed gas mixture

7a, 7b, 7c, 7d

catalytic Autothermal reformer

8a, 8b, 8c

Pre-reformer

9

synthesis gas

10

reactor for catalytic partial oxidation

11

Steam methane reformer

12a, 12b

Steam / feed gas mixture

13

lances to the entry of oxygen-containing gas

14

lances for entry of input and / or process gas

15

lances

16

Center of the circular reactor 7d

17

Container centerline of the circular reactor 7d

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 10230149 A1 [0013, 0014]
• EP 0989094 B1 [0016]
• US 6818198 B2 [0020]
• EP 1604948 A1 [0027]
• EP 0233076 B1 [0030, 0031]
• - DE 102006023248 A1 [0030]
• - EP 1927577 A1 [0031]
• - GB 2407819 A [0032]

Cited non-patent literature

• K. Heitnes et al., Catalysis Today 24 (1995) 211-216, Elsevier Science BV [0010]
• EHM Vermeiren et al., Catalysis Today 13 (1992) 427-436, Elesevier Science BV [0010]
• Rongchao Jin et al, Applied Catalysis A: General 201 (2000) 71-80, Elesivier Science BV [0010]
• - J. Warnatz, Ber. Bunsenges. Phys. Chem. 87 (1983) 1008-1022 [0014]
• - C. -J. Winter, et al. Springer-Verlag 1989 [0019]
• - C. -J. Winter, et al. Springer-Verlag 1989 [0019]
• V. Kah, V. Edition, Chemiewerk Leuna AG [0019]
• V. Kah, V. Edition, Chemiewerk Leuna AG [0019]
• R. Jin et al., Applied Catalysis A: General 201 (2000), 71-80, Elsevier Science BV [0021]

Claims (25)

A process for the soot-free production of synthesis gas from hydrocarbon-containing feed gas and oxygen-containing gas in a multi-stage cascade, which has at least one of the following stages: catalytic autothermal reforming, catalytic partial oxidation, characterized in that oxygen-containing gas and hydrocarbon-containing feed gas are fed to each stage of the cascade is converted to hydrogen-containing process gas and in series through the entire subsequent cascade. A method according to claim 1, characterized in that the balanceable H ₂ stream of a preceding stage with respect to the stoichiometry of the H ₂ O formation of the next level compensated for the O ₂ requirement of this subsequent stage maximum, but at most equal to 1.5 times the amount of the balance size , Method according to one of claims 1 or 2, characterized in that in the first stage of reforming the cascade, which operated as a catalytic autothermal reformer will, a higher steam-to-carbon ratio is realized, than in the subsequent stages of the cascade. Method according to one of claims 1 to 3, characterized in that in the first stage of the cascade a catalytic partial oxidation takes place. Method according to one of claims 1 to 4, characterized in that the individual stages of the cascade additionally steam is supplied. Method according to one of claims 1 to 5, characterized in that the hydrocarbon-containing feed gas before passing through a catalytic reactor stage together with steam subjected to a pre-reforming step. Method according to one of claims 1 to 6, characterized in that the hydrocarbon-containing feed gas before passing through the first catalytic reactor stage together is subjected to a pre-reforming step with steam. Process for the soot-free production of synthesis gas from a hydrocarbon-containing feed gas and from oxygen-containing gas and water vapor in a two-stage series circuit comprising in the first stage an allothermal steam methane reformer, and in the second stage a catalytic autothermal reformer, wherein the second stage, the hydrogen-containing process gas is fed to the first stage and in addition hydrocarbon-containing feed gas, steam and oxygen-containing gas is supplied, characterized in that • the H ₂ stream which can be balanced in a preceding stage, with reference to the stoichiometry of the H ₂ O formation of the subsequent stage, preferably the O ₂ requirement of this Compensated, but at most equal to twice the amount of balance size, and • the hydrocarbon-containing feed gas and the oxygen-containing gas separated from each other via devices that are on different levels with different orientation in the last kata lytic autothermal reforming stage, the oxygen-containing gas is introduced via at least one separate feed secantially to the center of the circular reactor above the catalyst bed, and the hydrocarbon-containing feed gas is preferably fed axially at the top of the reactor. Method according to claim 8, characterized in that that the process gas from the steam methane reformer with hydrocarbon Feed gas is mixed and this mixture axially at the top of the reactor is forwarded. Method according to one of claims 8 or 9, characterized in that the process gas from the steam methane reformer is mixed with hydrocarbon-containing feed gas and this Mixture via at least one separate feed secantially to the center of the circular reactor introduced the Katalystorbett in the catalytic autothermal reformer becomes. Method according to one of claims 8 to 10, characterized in that the process gas from the steam methane reformer via at least one separate feeder secantial to the center of the circular reactor above the catalyst bed is introduced into the catalytic autothermal reformer. Method one of claims 8 to 11, characterized in that in the catalytic autothermal Reformierungsstufe an additional separate oxygen supply takes place, with which a pilot burner is operated. Method according to one of claims 8 to 12, characterized in that in the steam-methane reformer a hydrocarbon feed gas and water vapor at a ratio of steam-to-carbon, calculated as a ratio of Molar amount of steam to molar amount of pure carbon in the hydrocarbon, from 2.0 to 4.0, preferably from 2.8, are reacted allothermically. Method according to one of claims 8 to 13, characterized in that in the catalytic autothermal Reformierungsstufe a hydrocarbon-containing feed gas as well an oxygen-containing gas and water vapor at a ratio of steam-to-carbon, calculated as a ratio of Molar amount of steam to molar amount of pure carbon in the hydrocarbon, from 0.0 to 3.0. Method according to one of claims 8 to 14, characterized in that the hydrocarbon-containing feed gas the catalytic autothermal reforming stage together with steam before going through this reforming stage in a pre-reformer is heated. Method according to one of claims 8 to 15, characterized in that the steam methane reformer a partial flow, consisting of at least 10%, preferably 25% based on the hydrocarbon-containing Feed gas is supplied to both stages. Apparatus for carrying out soot-free Production of synthesis gas in a multi-stage reactor cascade according to claim 1, containing • at least two catalytic reactor stages, • a device for Introduction of the hydrocarbon-containing feed gas into the first catalytic reactor stage, • a device for Introduction of oxygen-containing gas into the first catalytic Reactor stage, • a device for transfer of the process gas obtained in a reactor stage into a subsequent reactor stage, thereby marked that • the catalytic reactors over the process gas guide are connected in series, • one Apparatus for supplying oxygen-containing gas in the individual series-connected catalytic reactors provided is and • Devices for feeding hydrocarbon-containing feed gas in the process gas guide and / or in the individual series-connected catalytic reactors are provided. Device according to claim 17, characterized in that that the cascade consists of catalytic autothermal reformers. Device according to claim 17, characterized in that that the first stage of the cascade consists of a catalytic partial oxidation element consists. Device according to one of claims 17 19, characterized in that the inlet for the hydrocarbon-containing Feed gas of a catalytic reactor with the outlet of the gas connected to a pre-reformer. Device according to one of claims 17 to 20, characterized in that the inlet for the hydrocarbon-containing Feed gas of the first catalytic reactor of the cascade with the Outlet of the gas of a pre-reformer is connected. Apparatus for carrying out the soot-free production of synthesis gas in a two-stage reformer cascade according to claim 8, comprising • a steam-methane reformer, • a catalytic autothermal reformer, • a device for introducing the hydrocarbon-containing feed gas, in the steam-methane reformer, • a Device for introducing steam into the feed gas device, and • a device for transferring the process gas obtained in the steam methane reformer in the catalytic autothermal reformer, characterized in that • at least one device for gas entry at the reactor head of the catalytic autothermal Refor Mers is provided, as well as other devices for gas entry, which are aligned secantially to the center of the circular reactor and protrude at different levels with different orientation to the container central axis in the reactor. Device according to claim 22, characterized in that in that a device for mixing the process gas of the respective Reformers is provided with hydrocarbon-containing feed gas. Device according to one of claims 22 or 23, characterized in that an additional separate feed for oxygen-containing gas at the reactor head of the last catalytic autothermal reformer stage is provided, which is connected to a pilot burner. Device according to one of claims 22 to 24, characterized in that the inlet for the hydrocarbon-containing of the catalytic autothermal reformer with the outlet of the gas connected to a pre-reformer.