EP3638620A1

EP3638620A1 - Soot avoidance and/or soot reduction process and assembly

Info

Publication number: EP3638620A1
Application number: EP18730971.1A
Authority: EP
Inventors: Dietmar Rüger; Carl Berninghausen; Christian Klahn; Sebastian Becker; Robert Blumentritt
Original assignee: SunFire GmbH
Current assignee: SunFire GmbH
Priority date: 2017-06-12
Filing date: 2018-06-11
Publication date: 2020-04-22
Also published as: EP3638619A1; CA3067060A1; WO2018228642A1; WO2018228641A1; CA3067090A1; AU2018283056A1; BR112019022352A2; US20200179897A1; US11612872B2; CA3067090C; AU2018283056B2; EP3415466A1; ZA201906574B

Abstract

The invention relates to a soot avoidance and/or soot reduction process for avoidance and/or reduction of soot inside a synthesis gas and/or CO-containing gas production apparatus from the feed gases carbon dioxide, steam, hydrogen and/or a hydrocarbon-containing residual gas and electrical energy in RWGS processes, electrolyses for electrochemical decomposition of carbon dioxide and/or steam, reforming operations and/or synthesis gas production processes having at least one gas production unit, an electrolysis stack and/or a heater-reactor combination for performing an RWGS reaction and at least one cooling sector/recuperator for CO-containing gas and/or synthesis gas and to a soot avoidance and/or soot reduction assembly.

Description

Soot avoidance and / or soot reduction method and arrangement

The invention relates to a Rußvermeidungs- and / or Rußverminderungsverfahren for

Prevention and / or reduction of soot within a synthesis gas and / or CO-containing gas generating device from the feed gases carbon dioxide, water vapor, hydrogen and / or a hydrocarbon-containing residual gas and electric energy in RWGS processes, electrolysis for the electrochemical decomposition of carbon dioxide and / or Water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for performing a RWGS reaction, and at least one

Cooling section / recuperator for CO-containing gas and / or synthesis gas, as well as a

Soot avoidance and / or soot reduction arrangement.

It should be noted at this point that a "and / or" link listed in feature lists also applies to the directly associated "," links, for example the feature list "a, b, c and / or d" should be referred to as "a and / or b and / or c and / or d "in this disclosure.

If hot, CO-containing gases are cooled in heat exchangers, solid carbon, so-called soot, can form in the temperature range of about 300 ... 800 ° C, given the thermodynamic and kinetic conditions.

The following chemical reactions are mainly responsible for soot formation:

2 CO C0 ₂ + C ΔΗ _Κ = -172.5 kJ / mol R1

H ₂ O + C -132.0 kJ / mol of R2

<~ »H ₂ + C +74.9 kJ / mol R3

The formed soot settles on the heat exchanger surface and there leads to a deterioration of the heat transfer and to a blockage of the flow channels. Dirty heat exchanger surfaces reduce the proportion of heat that can be recovered and used from gas cooling. Clogged flow channels increase the

Flow loss and reduce the gas permeability of the apparatus, which must be compensated by higher compression of the gas. Both thus leads to

Deterioration in efficiency and deterioration of the efficiency of the overall process. Does the carbon make a chemical connection with the

The heat exchanger's construction material (carbide formation) can do that to one

Destruction of the heat exchanger (metal dusting). The term heat exchanger includes here also pipelines in which the CO-containing gas cools due to insufficient thermal insulation, which also can form soot. In general, heat exchangers in the sense of this disclosure can also be recuperators and the like.

The technical field is the cooling of hot, CO-containing gases after their

Production in gasification plants, C0 ₂ electrolyses and co-electrolyses, RWGS processes (reverse water gas shift processes) and / or reformers, which are operated with the aid of preferably regeneratively generated electric energy and synthesis gas production. The invention is concerned with how the formation of soot during gas cooling can be suppressed or prevented and how yet formed soot can be removed again from the heat exchanger surface.

From the prior art, different arrangements and methods with respect to this disclosure are known.

To assess the risk of soot formation, reference is made to the appended FIG. 9, which shows the state point of a synthesis gas, in order to illustrate the thermodynamic soot formation conditions. The composition of a (synthesis) gas whose individual gases consist only of the components C, O ₂ and H ₂ , in the C-0 ₂ -H ₂ -Standsdiagramm as a point (point 1) with the coordinates C, 0 ₂ and H ₂ are shown.

The sum of all the state points at which a gas mixture at a constant temperature and at a constant pressure (in this case 1 bar) just begins to form soot or at the

Gas mixture has reached the limit of absorption capacity of carbon, can be represented as an isotherm (soot limit at the corresponding temperature).

In the state area to the left of the soot boundary (toward the C corner) there are always 2 phases at once, the gas mixture and the solid soot. That the state point is formed by the composition of the gas mixture and the proportion of solid carbon.

The formation of soot is temperature and pressure dependent as shown in Figures 10 and 11. Fig. 10 shows the synthesis gas composition of an RWGS process as a function of equilibrium temperature at a pressure of 1 bar for a H ₂ -CO molar ratio of 2 and Fig. 11 shows the synthesis gas composition of an RWGS process as a function of equilibrium temperature at a pressure of 10 bar also for a H ₂ -CO molar ratio of 2.

The maximum temperature at which soot is still formed increases at higher pressures and also the amount of soot formed at a given temperature is greater at higher pressures. In the generation of CO-containing gases, one wants to know whether a gas is in the carbon black or not. For example, soot formation during the electrolysis of carbon dioxide in a solid oxide electro-lysing cell (SOEC) can lead to deposits on the electrolysis cells and clogging of the membranes, ultimately stopping the operation of the electrolysis.

The synthesis gas 1 in Fig. 9 should have been generated at 950 ° C and 1 bar. The soot limit of 950 ° C lies to the left of point 1. This means that the gas is outside the soot area under these conditions.

In an assumed isobaric cooling of the gas in a heat exchanger may, depending on the rate of cooling and the kinetics of the possible homogeneous and

heterogeneous chemical reactions still slightly change the gas composition. An equilibrium composition is usually not achieved, as the

Cooling rates are too high and thus the residence times will be too short. This is also not wanted, since the gas composition u.a. about the adaptation of

Reactor outlet temperature is controlled procedurally.

The position of the state point in the C-0 ₂ -H ₂ diagram remains unchanged, however, since none of the three components are added to or removed from the system.

The soot limit in the C-0 ₂ -H ₂ diagram applicable for each cooling (inter-) temperature shifts to the right. At about 570 ° C point 1 enters the soot area, assuming the thermodynamic equilibrium state, and remains in this area during further cooling.

Fig. 12 shows the course of the carbon activities of reactions R1, R2 and R3 starting from gas 1 (analogous to point 1 at 950 ° C). It is purely thermodynamic to assume soot formation in carbon activities of the single reactions of ac £ 1, with the driving force increasing to higher values a _c . At a _c <1, the reverse reaction is thermodynamically favored.

With gas composition assumed to be constant, the risk of soot formation increases during the gas cooling by the exothermic Boudouard (R1) and heterogeneous water gas reaction (R2). Throughout the temperature range, carbon black can be thermodynamically decomposed by reaction R3.

A qualitative statement on the basis of the carbon activities, from which temperature carbon black is formed during the gas cooling, is only possible under the assumption that eg reaction R3 is kinetically strongly inhibited. A first soot formation is ideally carried out only from about 680 ° C by reaction R1, wherein resulting carbon black can be consumed by reaction R2 until it forms thermodynamically soot at temperatures less than 630 ° C. This approach differs from the C-02 H ₂ diagram (soot formation <570 ° C), in which, as in a chemical reactor, all reactants are in thermodynamic equilibrium at all temperatures, but also has the disadvantage that the complex reaction system and the mutual influence of the reactions is disregarded.

Whether and how much soot in the overall balance of all participating homogeneous and heterogeneous reactions R1, R2 and R3 arises depends on the kinetics of the individual reactions under the conditions (pressure, temperature, residence time in the heat exchanger, catalytic effect of the construction material, etc.) is sufficiently high.

An assessment of the effectiveness of the measures is possible under consideration of both extreme cases.

In practice, at usual cooling rates and sufficiently high temperatures (> 500 ° C), according to experience still soot is formed, which in the course of the operating time in

Heat exchanger accumulates on the heat exchanger surface and in the flow channels and leads to problems there. Below 350-400 ° C is known to hardly form carbon black at the usual residence times.

For gasification or reforming, the prior art is carried out below.

In the gasification of coal with air or oxygen, as practiced by Shell, Siemens, Texaco et al., Water vapor is added to the gasification agent to convert the coal completely and without formation of soot in a gas. The Wasserdampfzumischung causes the gas composition is shifted in the direction of H ₂ 0 in the state diagram and thus is out of the Rußgebietes for the temperatures in question.

In the production of synthesis gas by reforming hydrocarbons, e.g.

Natural gas, as e.g. is also offered by Uhde and Linde

Excess steam suppresses soot formation in the reformer.

In "Diesel Steam Reforming in Microstructured Reactors", J. Thormann, Scientific Reports FZKA 7471, it is recommended to choose the highest possible steam to carbon ratio to avoid soot formation during reforming

Steam quantity at the expense of efficiency.

The patent EP 1717 198 A2 also states that a high vapor excess minimizes soot formation during synthesis gas production.

The cooling of the synthesis gas is generally carried out by quenching with WasserAdampf or cooled and recirculated synthesis gas. The problem of soot formation during the Cooling of the synthesis gas is just not described in the prior art of the production of CO-containing gases by gasification and reforming.

With regard to the RWGS process, the applicant's EP 20 49 232 B1 describes a method with the aim of recycling the combustion products carbon dioxide and water, as they occur in the exhaust gases from combustion processes or in the environment, into renewable synthetic fuels and fuels by electrical energy , which was not generated with the help of fossil fuels, but renewable. Here, the technical problem is solved by separating the chemically bound in the combustion process of carbon and hydrogen oxygen from the products of combustion carbon dioxide and water with the introduction of electrical energy, which was primarily using renewable energy sources, but not with the help of fossil fuels produced by according to the invention by electrolysis of water, or preferably steam,

produced hydrogen mixed with carbon dioxide to a carbon dioxide-hydrogen mixture to a molar ratio of 1 to 3.5, this is preheated in a Hochtemperaturrekuperator and then heated in an electrically heated device or an electric plasma generator to 800 to 5000 ° C, which forming synthesis gas used recuperator for preheating the carbon dioxide-hydrogen mixture, then directly cooled with deposition of the reaction water and then fed the present carbon monoxide carbon dioxide-hydrogen mixture of a Fischer-Tropsch or methanol synthesis and there converted into the products hydrocarbons or methanol which are cooled with the separation of water and condensed if necessary. In addition, it is also according to the invention that the recuperative preheating of the carbon dioxide-hydrogen mixture and its further heating takes place by supplying electrical energy in the presence of catalysts. Furthermore, according to the invention, the water used in the gas and product cooling is to be used together with external water for the direct cooling of the synthesis crude gas and the synthesis processes to vaporize it and to split the steam into electrolysis into hydrogen and oxygen.

In the following, we first refer to the attached Fig. 1 and the accompanying

Figure description referenced below, which shows and explains a schematic representation of a procedural circuit of the RWGS process.

The application of steam admixture in the gasification of the prior art e.g. in an RWGS process, the following description will be given with the aid of Fig. 13, namely admixing of steam with the production of synthesis gas in an RWGS process.

If one mixes the gas in Fig. 13, point 1, in an RWGS process of hydrogen and carbon dioxide on a suitable catalyst, for example nickel catalyst at 950 ° C and 1 bar has been generated and has a H ₂ -CO molar ratio of 2, in the gas generation of steam to, for example, in which one adds the feed gases to water vapor, shifts the

Gas composition towards the H ₂ 0 point. The amount of steam determines the location of point 2 in the state diagram. In a chosen example is the

Condition point 2 only at a temperature <300 ° C in the soot area. Due to the very slow kinetics of the soot formation reactions (R1, R2 and R3) at this temperature level, no soot would be likely to form.

The water vapor participates in the gas conversion reactions in the RWGS process and alters the gas composition, which also leads to a change in the H ₂ -CO molar ratio. At the same time, to obtain a H ₂ -CO molar ratio of 2, the amount of H ₂ feed gas must be reduced. The resulting gas composition shows point 3, which reaches the soot area at about 300 ° C.

On the basis of carbon activities and neglecting reaction R3, carbon black can theoretically be produced as soon as the temperatures below are reached:

Soot formation at T <[° C] point 1 point 3

Reaction R1 680 620

Reaction R2 630 560

The soot-reducing effect of the Wasserdampfzumischung is maintained, but is lower than in the boundary view in the thermodynamic equilibrium state by means of C-0 ₂ -H ₂ - diagram.

The price of water vapor mixing during gas production is a higher C0 ₂ content in the product gas.

With regard to the prior art for co-electrolysis, reference is made to document WO 2008 016 728 A2, which discloses a method / arrangement for generating a synthesis gas, wherein steam, carbon dioxide, hydrogen and nitrogen produced by nuclear thermal energy directly form a solid oxide electrolysis cell (SOEC) fed and with the application of nuclear electrical energy electrochemically to synthesis gas with a

Molar ratio H ₂ / CO of about 2/1 be worked up.

Furthermore, the document WO 2011 133 264 A1 discloses a method / arrangement for the electrochemical reduction of carbon dioxide to the product carbon monoxide at the cathode and supply of a reducing agent to rinse the anode. On the anode side is achieved by the oxidation of the reducing agent (eg hydrocarbons) an efficiency-increasing reduction of the oxygen partial pressure and the heating of the apparatus. The feed streams are heated recuperatively against the product streams. The invention further comprises the additional supply of steam to produce a synthesis gas. Furthermore, the publication WO 2013 131 778 A2 discloses a method / arrangement for producing high-purity carbon monoxide (> 90% by volume) by electrolysis of carbon dioxide, consisting of SOEC stack (<80% conversion) and a special gas separation unit. Other features here are the recirculation of (C0 ₂ / CO), the C0 ₂ purging of anode and / or stack housing, cleaning Feed-C0 ₂ and the pressure increase upstream of the gas separation unit. Furthermore, it is recognized that carbon deposits on the tube wall of the nickel-based material (Boudouard reaction) can form behind the stack during the cooling of the CO ₂ / CO mixture, which can lead to damage of the material by metal dusting. To prevent C formation and dusting, it is proposed to coat the material with Cu or Ni / Sn or to use Cu insertion tubes.

Document WO 2014 154 253 A1 goes deeper into the recuperative preheating of the feed gases compared to the above-mentioned method / arrangement and proposes further measures for avoiding the formation of carbon deposits and metal dusting in the system, namely quenching with inert gas (C0 ₂ or N ₂ ) to 400-600 ° C to avoid metaldusting, then recuperation for efficiency and further H ₂ S admixture in feed and / or downstream, to avoid soot formation in the system (50 ppb ... 2 ppm).

With regard to the co-electrolysis process for the production of synthesis gas according to the prior art, reference is made to the Fig. 2 below, which is a possible

procedural circuit of the co-electrolysis process shows.

In Fig. 14, which illustrates the state points of synthesis gases from co-electrolysis at different H ₂ O / C0 ₂ conversions, point 1 shows the feed gas mixture C0 ₂ and water vapor and point 2 the product gas compositions for 80% conversion.

Upon cooling of the feed gas in point 2, this passes at about 650 ° C in the Rußgebiet. It would form in the further cooling soot in the heat exchanger.

By reducing the C0 ₂ - or H ₂ 0 conversion from 80% to 60% of the

State point 3 reached. This point reaches the soot area at a temperature of 550 ° C during gas cooling.

A further reduction of the C0 ₂ - and H ₂ 0 conversion to 50% shows the state point 4. At this point, the soot formation would thermodynamically start at about 400 ° C in the gas cooling, but probably no longer occur for kinetic reasons.

A reduction in sales also results in an increase in the C0 ₂ content in the product gas and thus gas deterioration.

The sole electrolysis of carbon dioxide, ie without water vapor, can be treated in exactly the same way as the co-electrolysis of carbon dioxide and water vapor. On the basis of carbon activities and neglecting reaction R3, carbon black can theoretically be produced as soon as the temperatures below are reached:

Soot formation at T <[° C] point 2 point 3 point 4 conversion 80% 60% 50% reaction R1 700 650 625 reaction R2 680 610 590

The soot-reducing effect of the reduction in turnover is retained, but is lower than in the limit state consideration in the thermodynamic equilibrium state by means of C-0 ₂ -H ₂ diagram.

Further, in the prior art for eliminating soot, soot blowing with steam and mechanical soot removal by knockers, ball-sweepers, brushes, etc. are known.

The following will be further detailed to the other known printed-writing state of

Technology detailed:

From the publication WO 2010/020358 A2 is a method and apparatus for the soot-free production of synthesis gas from hydrocarbon-containing 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 in series all subsequent Cascade goes through. 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 fed, wherein the catalytic autothermal reformer is fed at most 1, 5 times the amount of O ₂ , which corresponds to the amount of H ₂ , which is formed in the allothermal steam methane reformer, and the hydrocarbon-containing feed gas and the oxygen-containing gas separated be fed 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 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.

This publication WO 2010/020358 A2 thus discloses a multi-stage process for soot-free steam reforming of hydrocarbon-containing starting gases by means of catalytic all-thermal and catalytic auto-thermal reforming. The goal is

To prevent soot formation on the catalyst. The reforming of hydrocarbons (here am Example of CH ₄ ) with water vapor is an endothermic process and proceeds according to the following reaction:

CH ₄ + H ₂ 0 ^■ »CO + 3 H ₂ AH _R = +206.2 kJ / mol

Water vapor is a necessary reaction partner of methane for the formation of CO and H ₂ in this process. By increasing the amount of water vapor, by using the homogeneous water vapor reaction, additional hydrogen can be generated from the CO formed:

CO + H ₂ 0 C0 ₂ + H ₂ ΔΗ _Κ = -41, 2 kJ / mol

Again, water vapor is the main reaction partner. The heat required for the reformation reaction can be supplied externally (allothermic) or by partial oxidation of CH ₄ and / or H ₂ and / or CO with an oxygen-containing oxidant in the process itself (autothermic).

CH ₄ + 0.5 O ₂ CO + 2H ₂ AH _R = -36 kJ / mol

H ₂ + 0.5 0 ₂ ^■ »H ₂ 0 ΔΗ _Κ = -242 kJ / mol

CO + 0.5 0 ₂ C0 ₂ AH _R = -283 kJ / mol

In the case of water vapor or 0 ₂ deficiency, there is the danger that carbon black forms on the catalyst, which causes poisoning of the catalyst and thus reduces the catalytic effect.

In the publication WO 2010/020358 A2, the cooling of the gas generated in the reforming and thus the soot reduction or soot reduction during cooling is not considered. In the publication WO 2010/020358 A2 after the gas production

introduced water vapor streams 3b, 3c, 3d are correct to the respectively before the other reforming stages 1 b, 1 c and 1 d necessary amount of steam to continue the running in these stages reforming reactions. No additional amount of water vapor is introduced at the end of all process stages in order to suppress or avoid soot formation during gas cooling. The amounts of hydrogen 6a, 6b and 6c introduced into the process stages 1b, 1c and 1c are the amount of hydrogen produced in the preceding process stages and not an additional amount of hydrogen introduced before or at the end of the overall process, which is the formation of soot upon cooling to suppress or prevent the generated gas.

In WO 2010/020358 A2 is the soot in the production of synthesis gas from hydrocarbon-containing gases by multi-stage allothermic or autothermal steam reforming, in which the supplied water vapor necessary reaction gas and the subsequent process stages supplied hydrogen is produced product and no additional Water vapor or hydrogen for soot prevention and soot suppression is supplied. Since it continues to be the gas generation and not the gas cooling process, the disclosure according to the document

WO 2010/020358 A2 with respect to the present invention does not oppose. From the document WO 2015/185039 A1, an electrolysis method with an electrolytic cell using at least one recirculating flushing medium is known. Furthermore, this document relates to an electrolysis device. In a SOEC electrolysis, water vapor and / or carbon dioxide are decomposed electrolytically into hydrogen, carbon monoxide and oxygen. The product gas H ₂ / CO is removed from the cathode compartment by means of purge gas (50) and separated into product gas H ₂ / CO, purge gas (50) or purge gas-product gas mixture (50 + H ₂ / CO) in the gas separation device located behind the electrolysis , The separated purge gas (50) or the separated purge gas product gas mixture (50 + H ₂ / CO) or a part of the

Product gases H ₂ / CO are recycled, added to the reactant gas stream before the electrolysis and again as a cathode purge gas for the removal of the electrolysis products H ₂ / CO the

Cathode side of the electrolysis used. The purge gas (50) is inert to the

Product gas H ₂ / CO. A gas cooling behind the electrolysis is not the subject of

Invention in D2, but can be used. The rinsing of the cathode side can also be done by the unreacted portion of the supplied reactant gas (C0 ₂ / H ₂ 0), which can also be recycled after gas separation.

The document WO 2015/185039 A1 is thus concerned with the provision and the effective use of cathode and anode scavenging gas by the use of a gas separation device downstream of the electrolysis and recycling and reintroduction of the separated purge gas stream as purge gas in the electrolysis. The purge gas does not necessarily have to be H ₂ or H ₂ O on the cathode side. It must be only inert to CO and H ₂ on the cathode side. The document WO 2015/185039 A1 does not therefore relate to soot avoidance or

Rußverminderungsverfahren.

The publication DE 42 35 125 A1 proposes a process for the production of synthesis gas and an apparatus for carrying out this process. In known processes for the production of synthesis gas fossil materials, such as. As coal or natural gas, as starting materials. This contributes to a further shortage of raw material reserves as well as to an increase in C0 ₂ emissions. The process of the invention is

Synthesis gas by a direct reduction of carbon dioxide to carbon monoxide without

Use of fossil fuels produced as starting materials. The carbon dioxide is in particular from the atmosphere or from non-fossil emissions such. B.

Cement production emissions won. The liquid fuels produced from this synthesis gas, such as. As methanol, are thus recoverable energy sources of a closed carbon dioxide-fuel cycle.

In this document DE 42 35 125 A1, the hydrogen is not mixed in addition to avoid the soot formation in the gas cooling in the synthesis gas produced, but in this multi-step process, the resulting in electrodialysis H ₂ in the H ₂ -CO-containing Synthesis gas from the electrolysis mixed into the finished synthesis gas, so this document does not concern Rußvermeidungs- or Rußverminderungsverfahren.

The publication WO 2014/097142 A1 describes a process for the parallel production of hydrogen, carbon monoxide and a carbon-containing product which is characterized in that one or more hydrocarbons are thermally decomposed and at least part of the resulting pyrolysis gas from the reaction zone of the

Stripped off at a temperature of 800 to 1400 ° C and decomposed with

Carbon dioxide is converted to a carbon monoxide and hydrogen-containing gas mixture, a synthesis gas.

In the publication WO 2014/097142 A1, the hydrogen is not additionally mixed in the generated synthesis gas in order to avoid the formation of soot in the gas cooling, but serves to set the desired H ₂ : CO molar ratio in the finished synthesis gas. The addition of hydrogen-containing gas mixture from the pyrolysis directly into the gas stream after the RWGS process reduces the generatable in the RWGS-level amount of CO, since heat and H ₂ is missing for the chemical conversion of C0 _2, corresponding to

C0 ₂ + H ₂ CO + H ₂ 0 AH _R = +41, 2 kJ / mol,

which also lacks the characteristic of the electric power, and this document therefore does not anticipate the present Rußvermeidungs- or Rußverminderungsverfahren or Rußverminderungsverfahren.

Summarizing the state of the art, it is thus known:

- The generation of CO-containing gases by RWGS, Co and CO _z -SOEC

the recuperative preheating the Feedgase.bzw. Cooling of the hot gases leaving the reactor

the recirculation, even after gas separation

Measures to prevent soot formation / metal dusting in the system, too

Cooling section, with C0 ₂ electrolysis

o a. Coating of the material (Ni / Sn, Cu)

if. Quenching with inert gas (C0 _2, N ₂₎ leads to high cooling rates o c. H ₂ S admixture to avoid C formation and metal dusting in the

System is known.

- Water vapor excess with H ₂ 0 addition before reactor deteriorates gas quality (more C0 ₂ ).

The following will discuss the disadvantages and problems of the prior art

executed. In the cooling of CO-containing gases, in particular of synthesis gases after generation in RWGS processes, co-electrolysis, electrochemical electrochemical

Decomposition of carbon dioxide, reforming plants, etc., forms soot.

The formed soot settles on the heat exchanger surface and there leads to a deterioration of the heat transfer and to a blockage of the flow channels. Especially the danger of blockage of the flow channels of the gas cooling sections is in large-scale systems such as gasification and reformer systems also because of there usually

Quenching is usually of little relevance, but increases as the system size declines (decentralized RWGS or C0 ₂ / Co electrolyzers).

Dirty heat exchanger surfaces reduce the proportion of heat that can be recovered and used from gas cooling.

Clogged flow channels increase the flow pressure loss and reduce the

Gas permeability of the apparatus, which must be compensated by higher compression of the gas.

If the carbon makes a chemical connection with the construction material of the

Heat exchanger on (carbide formation), this can lead to destruction of the heat exchanger (metal dusting).

Plant shutdowns for cleaning purposes and additional revisions reduce the

Availability of the plant.

The consequences are a deterioration in efficiency, lower availability and thus a deterioration in the efficiency of the overall process.

An increase of the water vapor content in the feed gas stream leads to the reduction and possibly also the avoidance of soot formation during the gas production and during the gas cooling. The disadvantage of increasing the water vapor content is that due to the chemical

Equilibrium during gas generation also more carbon dioxide is formed.

High concentrations of carbon dioxide in the synthesis gas are often undesirable because carbon dioxide is usually not involved in the synthesis reactions and the

Partial pressure of the synthesis gas components reduced. Is the synthesis gas after the

Gas production compressed to higher pressures, additional compressor power is required. Therefore, expensive and expensive gas purification processes, e.g. chemical washes (MEA, MDEA, etc.), physical washes (pressurized water wash, Rectisol wash, etc.),

Pressure swing, membrane separation, etc. required to remove the unwanted C0 ₂ from the syngas after gas generation. The same effect has the reduction of H ₂ 0 / C0 ₂ -satz in the co-electrolysis. Here, too, with the reduction of the conversion due to the chemical equilibrium in the gas production in the electrolysis stack, the C0 ₂ content in the synthesis gas increases.

The coating of the catalytically effective heat transfer surface e.g. with Ni / Sn, Cu, suppresses the catalyzed soot formation and is thus able to extend the operating time between two cleaning cycles. In addition, the layer protects the construction material from metal dusting. However, as experience has shown, a protective layer can not completely prevent soot formation.

An admixture of H ₂ S is complicated and expensive, since the gas must then be cleaned again in order not to poison the subsequent catalytic synthesis.

Small compact heat exchangers, e.g. Plate heat exchangers from the company Heatric,

allow high cooling rates, which ensures that the gas temperature quickly reaches a temperature range in which the kinetics for soot formation is too slow.

At least, so that the soot formation rate can be reduced.

The disadvantage of these heat exchangers, however, is that especially in systems with low power, the cross sections of the flow channels in the heat exchangers are relatively small and thus increases the risk of clogging of the channels with soot.

High cooling rates are also indicated by u.a. Quenching of the hot

Synthesis gas stream achieved with water. Possibly formed soot is usually discharged without problems with the excess quench water from the quencher and can be separated by filters from the water.

The disadvantage of gas quenching is that the sensible heat of the hot synthesis gas is converted into predominantly sensible heat of the quench water at a low temperature level. Thus, this heat is no longer available for preheating the feed gases and must be covered by additional energy supply to the process. The efficiency of the process is deteriorating and the cost of providing energy is increasing.

Inert gas quenching, such as C0 ₂ or N ₂ , degrades gas quality and would require expensive gas purification processes.

During sootblowing, an increased amount of gas is released for a short time or longer

Heat exchanger given so that the flow rate increases and the adhering soot can be blown out. Due to the increased flow velocity, the pressure loss via the heat exchanger increases in part considerably. Especially in co-electrolysis with electrolysis cells based on SOC lead strong Pressure fluctuations to impermissibly high differential pressures across the electrolysis cells, which leads to the breakage and thus the destruction of the cells.

With some mechanical soot cleaning options, such as the use of brushes, scratches, etc., it is necessary to shut down the syngas plant, which shortens plant availability and uptime.

Knockers for Rußabbreinigung during operation of the system are problematic in that the heat exchangers are used at high gas temperatures 850 ... 950 ° C and a mechanical vibration stress in this temperature range leads to problems in the strength of the materials.

It is an object of the present invention to eliminate the above-mentioned problems and disadvantages of the prior art and to provide a soot avoidance and / or reduction method which enables low carbon and high efficiency operation free from soot.

These objects are achieved with a Rußvermeidungs- and / or - erminderungsverfahren according to the main claim and corresponding thereto arrangements.

Soot prevention / soot reduction:

The soot avoidance and / or Rußverminderungsverfahren for avoiding and / or reducing soot within a synthesis gas and / or CO-containing gas generating device from the feed gases carbon dioxide, water vapor, hydrogen and / or a hydrocarbon-containing residual gas and electric energy in RWGS processes, electrolysis for the electrochemical decomposition of carbon dioxide and / or water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for carrying out a RWGS reaction, and at least one cooling line / recuperator for CO-containing Gas and / or synthesis gas,

is characterized in that an additional gas, liquid and / or gas mixture is added before being fed into the gas production in the feed gas stream and / or after gas production in the CO-containing gas / synthesis gas, wherein the additional gas, liquid and / or gas mixture is selected from:

a) water vapor for increasing the water vapor content in the generated gas,

this being introduced after synthesis gas production;

b) hydrogen to increase the hydrogen content in the gas produced, wherein

this introduced into the feed gas stream or after the synthesis gas production

becomes;

c) hydrogen-rich gas for cooling the CO-rich gas stream, this Hydrogen-rich gas is externally supplied or produced by separate C0 ₂ - and H ₂ 0 electrolysis, and the hydrogen-rich gas in the CO-rich

Gas stream is mixed, wherein the hydrogen-rich gas when produced via the separate electrolysis process prior to interference recuperative against

is cooled to be heated water vapor and / or C0 ₂ stream;

and or

d) water to cool the CO-containing gas stream before a

Hydrogen interference.

Further, the soot avoidance and / or soot reduction method for preventing and / or reducing soot within a synthesis gas and / or CO containing gas producing apparatus from the feed gases is carbon dioxide, water vapor, hydrogen and / or a hydrocarbonaceous residual gas and electric power in RWGS processes , Electrolysis for electrochemical decomposition of carbon dioxide and / or water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for performing a RWGS reaction, and at least one CO cooling / Rekuperator -containing gas and / or synthesis gas,

characterized in that

after gas generation in the CO-containing gas / synthesis gas water vapor is introduced to increase the water vapor content in the gas produced.

Further, the soot avoidance and / or soot reduction method for preventing and / or reducing soot within a synthesis gas and / or CO-containing gas producing apparatus from the feed gases is carbon dioxide, water vapor, hydrogen and / or a hydrocarbonaceous residual gas and electric power in RWGS processes , Electrolysis for electrochemical decomposition of carbon dioxide and / or water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for performing a RWGS reaction, and at least one CO cooling / Rekuperator -containing gas and / or synthesis gas,

characterized in that

Before feeding into the gas production in the feed gas stream and / or after the gas production in the CO-containing gas / synthesis gas hydrogen is introduced to increase the hydrogen content in the gas produced.

In addition, the soot-avoidance and / or soot-reduction method is for

Prevention and / or reduction of soot within a synthesis gas and / or CO-containing gas generating device from the feed gases carbon dioxide, water vapor, Hydrogen and / or a hydrocarbon-containing residual gas and electric energy in RWGS processes, electrolysis for the electrochemical decomposition of carbon dioxide and / or water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for implementation an RWGS reaction, and at least one

Cooling section / recuperator for CO-containing gas and / or synthesis gas,

characterized in that

after gas generation in the CO-containing gas / synthesis gas, hydrogen-rich gas for cooling the CO-rich gas stream, this hydrogen-rich gas being externally supplied or produced by separate C0 ₂ and H ₂ 0 electrolysis, and the hydrogen rich gas is mixed into the CO-rich gas stream, wherein the hydrogen-rich gas is recuperatively cooled against heated water vapor and / or C0 ₂ stream when prepared via the separate electrolysis process prior to mixing.

In addition, the soot avoidance and / or Rußverminderungsverfahren for avoiding and / or reducing soot within a synthesis gas and / or CO-containing gas generating device from the feed gases carbon dioxide, water vapor, hydrogen and / or a hydrocarbon-containing residual gas and electric energy in RWGS- Processes, electrolysis for the electrochemical decomposition of carbon dioxide and / or water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for performing a RWGS reaction, and at least one cooling line / recuperator for CO-containing gas and / or synthesis gas,

characterized in that

after gas generation in the CO-containing gas additional water for cooling the CO-containing gas stream is mixed before a hydrogen mixture.

According to the arrangement, the soot-avoidance and / or soot-reducing arrangement, in particular in conjunction with a soot-evisceration and / or soot-reduction method disclosed herein, on or within a synthesis gas and / or CO-containing gas generating device from the feed gases carbon dioxide, water vapor, hydrogen and / or a hydrocarbon-containing residual gas and electric energy in RWGS processes, electrolyses for the electrochemical decomposition of carbon dioxide and / or water vapor, reforming processes and / or synthesis gas production processes with at least one gas generation unit, an electrolysis stack and / or a heater-reactor combination for carrying out an RWGS reaction , and at least one cooling line / recuperator for CO-containing gas and / or synthesis gas,

characterized in that before feeding into the gas production in the feed gas stream and / or after the gas production in the CO-containing gas / synthesis gas an additional gas, liquid and / or

Gas mixture supply is provided, whereby by this supply water vapor,

Hydrogen-rich gas from an external feed device, hydrogen-rich gas from a separate C0 ₂ - and H ₂ 0 electrolysis and / or water are supplied.

Soot reduction and / or soot reduction by increasing the water vapor content in the generated gas:

To at a plant for the production of synthesis gas from carbon dioxide, water vapor and / or hydrogen and a hydrocarbon synthesis syngas and

Electric energy consisting of at least one gas generating unit, e.g. a co-electrolysis stack or a heater-reactor combination for carrying out the RWGS reaction, and a recuperative syngas cooling, it is proposed to suppress the soot formation during the gas cooling or possibly avoid, is proposed by admixing water vapor into the synthesis gas after gas production the

To increase water vapor content in the synthesis gas produced.

If the product gas (Fig. 13, point 1), which is produced at 950 ° C, initially cooled to about 600 ° C, then mixes the water vapor and then immediately further cooled, a gas conversion due to the water vapor due to the lower kinetics and the missing catalyst are largely avoided. It would turn out the state point 2, but compared to the point 1 only with a higher

Water content and (almost) unchanged H ₂ -CO molar ratio.

The Wasserzampfmischung can be done in two ways.

The first possibility is that the colder steam (about 150 ° C) is added directly to the approximately 600 ° C hot gas. That would be like a quench with gas. In this case, the product gas loses exergy, and in a recuperative preheating of the feed gases would their

Reduce preheating temperature, which would have to be compensated by a higher electrical energy demand in the RWGS process.

In the second possibility of Wasserzampfzumischung the colder water vapor is first preheated recuperatively against a partial stream of the gas-water vapor mixture to be further cooled. The exergy loss is lower, and it must be less

Electric energy for reheating the feed gases are applied.

The water vapor admixture to the product gas 1 produced may also be at 950 ° C, i. without prior intermediate cooling, immediately before the subsequent gas cooling.

Any still occurring homogeneous gas reactions can be considered in the adjustment of the product gas composition, for example by varying the amounts of feed gas. The water vapor has in the admixture after the actual gas generation only the task to reduce the formation of soot and suppress at best. The energy content of the steam is not used. It is usually removed to the atmosphere in the final cooling of the gas. Soot reduction and / or soot reduction by H ₂ excess

In order to suppress the formation of soot during the gas cooling or to avoid altogether, it is further proposed, with an additional hydrogen flow, which is mixed either to the feed gas or the synthesis gas after gas generation, to increase the hydrogen content in the synthesis gas produced. The additional hydrogen flow is after the

Gas cooling again from the synthesis gas by a suitable device, e.g. a

Membrane separation plant removed so that the synthesis gas has the desired H ₂ -CO molar ratio. The separated hydrogen is recycled by means of a compressor and mixed again with the feed gas stream or the synthesis gas stream.

The admixture of hydrogen to the feed gases of a RWGS process or a co-electrolysis shifts the gas toward the hydrogen corner and thus out of the soot area.

The effectiveness of this measure depends on the kinetics, especially of the reactions R2 and R3.

In Fig. 15, the representation of the state points of a co-electrolysis process with H ₂ - excess is shown. The state diagram Fig. 15 shows the admixture of a H ₂ -rich recycle gas (point 2) to a H ₂ 0-C0 ₂ feed gas stream (point 1) before co-electrolysis. The electrolytic decomposition of the mixed gas (point 3) gives the gas after co-electrolysis (point 4).

After the separation of water by condensation and the sufficient recycle gas (point 2), for example by means of a suitable membrane or other gas separation device from the gas point 4, the synthesis gas (point 5) with the desired H ₂ -CO molar ratio of 2.

The approximately 850 ° C hot gas at point 4 after co-electrolysis is cooled. Although it enters the soot area at a temperature <300 ° C, it will not form soot during cooling due to the low kinetics of soot formation reactions at temperatures below 300 ° C.

Even the approximately 30 ° C cold gas at point 5 after the water and H ₂ gas separation will no longer form carbon black at this temperature. The H ₂ 07C0 ₂ conversion of the gas point 3 in the co-electrolysis to the gas in point 4 is only 60%, since higher conversions increase the risk of soot formation again.

Nevertheless, this anhydrous gas has a lower C0 ₂ content (0.0973 kmol / kmo) than the gas at the same conversion but without hydrogen admixture (see Fig. 14, C0 ₂ = 0.1772 kmol / kmo).

The reason for this is that the excess of hydrogen is the chemical balance of the reaction

C0 ₂ + H ₂ - »CO + H ₂ 0 R4 shifts in the direction of the reaction products, thus reducing the C0 ₂ content in the gas. Soot avoidance and / or soot reduction by quenching (separate C0 ₂ and H ₂ 0 electrolysis, quenching of the CO-rich stream)

To suppress in a system for the production of synthesis gas from carbon dioxide, water and a hydrocarbon synthesis syngas and electric energy, which consists of a co-electrolysis stack and a recuperative synthesis gas cooling, the soot formation during the gas cooling or avoid possible, it is proposed that Performing water vapor and C0 ₂ electrolysis in two separate electrolysis stacks to cool the generated hydrogen-rich gas recuperatively against the steam and / or C0 ₂ stream to be heated and then mix in the hot CO-rich gas stream from the C0 ₂ electrolysis.

By mixing the cooled hydrogen into the hot CO-rich gas stream, it is rapidly cooled so that the kinetics of the carbon black formation reactions are insufficient to form carbon black.

In an extended embodiment, it is proposed to quench the hot CO-containing gas stream prior to hydrogen mixing by mixing in water. The

Intermixing of water allows even faster gas cooling than the mixing of cold hydrogen.

A disadvantage of quenching with water is that the heat for the product gas cooling is not available, but must be dissipated as condensation heat at low temperatures.

When quenching with gas, the temperature level of heat recovery from the still necessary synthesis gas cooling is reduced, so that the heat in the process itself, for example, for the recuperative feed gas preheating to the highest possible temperature level, can not be fully utilized. Both in the gas quenching and quenching the lack of heat for the recuperative preheating of the feed gases but can be covered by otherwise unused heat from the 0 ₂ -containing exhaust gas, so that hardly any loss of efficiency occur.

Fig. 16 shows the representation of the state points of a co-electrolysis process with separate electrolyses and water quenching of the CO-rich synthesis gas. It shows the electrolytic decomposition of C0 ₂ (point 1) and H ₂ 0 (point 4) and the subsequent quenching with water.

After C0 ₂ -SOEC, the formed CO-containing gas (point 2) is quenched with water (point 3). The H ₂ -rich gas (point 5) from the H ₂ 0-SOEC is recuperatively cooled in a heat exchanger. Both cold gas streams become ready after cooling

Synthesis gas (item 6) mixed.

After condensing out the excess water vapor in the gas mixture, the finished synthesis gas is obtained (item 7).

In Fig. 17 is the representation of the state points of a co-electrolysis process with separate electrolysis and quenching of the CO-rich synthesis gas with cooled

Hydrogen shown. It shows the quenching of the hot CO-containing gas with recuperatively cooled hydrogen.

After C0 ₂ -SOEC, the CO-containing gas formed (point 2) is quenched with cooled H ₂ -rich gas (point 5). The H ₂ -rich gas (point 5) from the H ₂ 0-SOEC is previously cooled recuperative in a heat exchanger. The resulting gas mixture (item 6) is cooled, and after the separation of the condensate, the finished synthesis gas is obtained (item 7).

Hereinafter, embodiments of the invention with reference to the accompanying

Drawings are described in detail in the description of the figures, which are intended to illustrate the invention and are not intended to be limiting:

Show it:

Fig. 1 is a schematic representation of a procedural circuit of the RWGS

process;

Figure 2 shows a possible procedural circuit of the co-electrolysis process.

Fig. 3 shows a RWGS process for the production of synthesis gas, in which to avoid

Soot formation after intercooling water vapor is mixed into the hot, to be cooled synthesis gas;

Fig. 4 shows an RWGS process in which the steam is mixed before mixing into the

intermediate-cooled synthesis gas is preheated by process heat; Fig. 5 shows a co-electrolysis process with steam mixing before gas cooling with preheating of the steam by process heat;

Figure 6 shows a co-electrolysis process with hydrogen surplus mode to avoid soot formation during gas cooling.

FIG. 7 shows an electrolysis process for the production of synthesis gas from water vapor and carbon dioxide with the aid of two separate electrolyses for water vapor and carbon dioxide in a first variant;

Fig. 8 shows an electrolysis process for the production of synthesis gas from water vapor and

Carbon dioxide by means of two separate electrolyses for water vapor and carbon dioxide in a second variant;

The o.g. Production of the synthesis gas via the reverse water gas shift reaction, in short: RWGS, in an RWGS reactor, recuperative cooling and condensation according to the prior art is practiced by the applicant.

Fig. 1 shows a schematic representation of a procedural circuit of the RWGS process.

As feed gases for the RWGS process are carbon dioxide C0 ₂ , hydrogen H ₂ , possibly residual gases from a Fischer Tropsch synthesis SPG, which unreacted

Synthesis gas components contains carbon monoxide and hydrogen and carbon dioxide and low hydrocarbons, and water vapor H ₂ Og used.

The feed gas mixture 1 is called in the recuperator 2 against the approximately 900 to 950 ° C.

Preheated synthesis gas stream 6 and then fed as stream 3 to the electric power operated heater 4.

In the heater 4, the gas mixture 3 is further heated and thereby fed so much heat that in the subsequent catalytic reactor 5, the endothermic reverse water gas shift reaction (RWGS reaction)

C0 ₂ + H ₂ ^ CO + H ₂ O R 4

and the endothermic reforming reactions (example)

C ₃ H ₈ + 3 H ₂ O -> 3 CO + 7 H ₂ R 5 CH ₄ + H ₂ O - CO + 3 H ₂ R6. The gas cools down.

Since the amount of heat that can be supplied in the heater 4 is limited due to the maximum permissible temperature of the materials of construction used, it may be necessary to achieve a certain amount Synthesis gas quality in the synthesis gas 6 to achieve a number of heater-reactor combinations 4 and 5 provide.

The about 900 to 950 ° C hot synthesis gas 6 is recuperatively cooled in the heat exchanger 2 against the heated feed gas 1 and then in operated with cooling water end cooler 7. During the cooling of the synthesis gas, water of reaction can condense out. The condensate 8 is discharged from the process.

During the cooling of the synthesis gas stream 6 in the heat exchanger 2, according to the reaction equations R1, R2 and R3, soot can form, which settles on the heat exchanger surface and deteriorates the heat transfer, so that less heat is available for heating the feed gas. This lack of heat must be additionally applied by the electric heater 4, which deteriorates the efficiency of the process.

At the same time, the synthesis gas stream 6 is cooled less, which must be compensated by the final cooler 7.

The deposited in the heat exchanger 2 soot also clogs the gas channels in the heat exchanger. The thus increasing flow pressure loss is measured by the differential pressure measurement 9 and must be compensated by a higher pressure of the supplied feed gas streams C0 ₂ , H ₂ , SPG and H ₂ Og. If this is not possible, the total quantity of feed gas must be reduced, which ultimately leads to a reduction in the output of the RWGS plant.

If the contamination of the heat exchanger with soot is too high, the process for cleaning or renewing the heat exchanger must be interrupted or completely shut down.

Fig. 2 shows a possible procedural circuit of the co-electrolysis process of the prior art.

The feed gases carbon dioxide C0 ₂ and water vapor H ₂ Og are mixed and recuperatively cooled as gas mixture 100 in the heat exchanger 101 against the hot

Synthesis gas 107 preheated as far as possible.

After the recuperative preheating follows in the heater 103 operated with electric energy, a further heating of the gas 102 to the inlet temperature in the electrolysis stack 105 of about 850 ° C. In the electrolysis stack 105, the water vapor and the carbon dioxide of the gas mixture 104 by means of electrical energy 106 electrolytically in hydrogen and

Carbon monoxide and oxygen decomposed.

The electrolytic decomposition is not complete and the synthesis gas 107 leaving the stack 105 is largely in chemical equilibrium, so that in the

Gas mixture 107 in addition to hydrogen and carbon monoxide also water vapor, Carbon dioxide and methane are included. Typical H ₂ O or C0 ₂ decomposition levels in SOC electrolyses are approx. 60-80%.

The synthesis gas 107, which has a temperature of approximately 850 ° C., is first recuperatively cooled in the heat exchanger 101 against the feed gas mixture 100 to be heated and then in the final cooler 108 operated with cooling water. The resulting in the cooling by condensation of the residual steam in the synthesis gas condensate 109 is discharged from the process.

The cooled syngas SYG is supplied for subsequent use.

The electrolytically separated in the electrolysis stack 105 oxygen is on the anode side of the stack of purge air air preheated in the recuperator 201 against the cooled oxygen-air mixture 110 and then reheated in the electric heater 203 to about 850 ° C, removed and after cooling discharged in the recuperator 201 as exhaust gas EXG to the atmosphere.

During the cooling of the synthesis gas 107 in the heat exchanger 101, the gas enters the soot area and soot is produced.

Deposits of soot during the cooling of the gas 107 in the heat exchanger 101 increases the pressure loss 111 via the heat exchanger 101 on the synthesis gas side. This increases the differential pressure 211 between the anode and cathode side of the

Electrolysis stacks 105, which can lead to breakage of individual cells and thus to performance losses and total failure of the co-electrolysis system.

Hereinafter, the embodiments for soot prevention and soot reduction are executed.

Fig. 3 shows a RWGS process for the production of synthesis gas, in which, to avoid soot formation after an intermediate cooling water vapor H ₂ 0g.2 is mixed in the hot, to be cooled synthesis gas (Wasserdampfzumischung before the

Synthesis gas cooling without steam preheating (RWGS)). The steam comes from an external source and is in this variant before interference in the hot

Synthesis gas not preheated by process heat.

In contrast to Fig. 1, the approximately 900 to 950 ° C hot synthesis gas 6 is first cooled in the recuperator 2.2 to a temperature of about 600 to 650 ° C. The temperature of the intermediate cooling may only be so low that the state point of the cooled

Synthesis gas in the state diagram (Fig. 13) is still outside the Rußgebietes at the appropriate cooling temperature. So that no soot is still formed in the heat exchanger 2.2. In the intercooled synthesis gas stream 10, water vapor H ₂ 0g.2 is mixed in from an external source. Due to the water vapor mixing, the state point of the

Synthesis gas in the state diagram (Fig. 13) in the direction of water shifted. Thus, the synthesis gas-water vapor mixture 11 reaches the soot area, preferably at lower temperatures, where the kinetics no longer allow soot formation.

The further cooling of the gas mixture 11 takes place in the recuperator 2.1 against the

heated feed gas mixture 1 and then in the final cooler. 7

The resulting amount of condensate 8 is higher than in the prior art due to the Wasserdampfzumischung.

The water vapor mixture in the synthesis gas to be cooled is also without

Intermediate cooling of the synthesis gas feasible.

The disadvantage of the above-described process with steam mixing is that the mixing of the relatively cold steam into the hot synthesis gas to be cooled exergy is lost and thus the feed gases can not be so high preheated. in the

Electric heater 4 thus needs more electric power to be used to the same

Preheat temperature as in the process of the prior art in front of the reactor 5 to achieve.

Fig. 4 therefore shows an RWGS process in which the steam is preheated by process heat before mixing into the intercooled synthesis gas and thus the exergy loss due to the steam mixture is lower (steam admixing before synthesis gas cooling with steam preheating (RWGS)).

The approximately 900 to 950 ° C hot synthesis gas stream 6 is first recooled as in the process Fig. 3 recuperative against the heated feed gas mixture in the heat exchanger 2.2 to about 600 to 650 ° C.

In the intercooled gas stream 10 water vapor H ₂ 0g.2 is mixed from external sources, which was previously preheated in the recuperator 2.3 against the partial stream 12.2 of the synthesis gas - steam mixture 11.

The other partial stream 12.1 of the synthesis gas-steam mixture 11 is used for the first preheating stage of the feed gas mixture 1 in the heat exchanger 2.1.

The recuperative cooled synthesis gas streams 13.1 and 13.2 are in the

Cooling chillers 7.1 and 7.2 cooled against cooling water to the desired final temperature. The condensate streams 8.1 and 8.2 are removed from the process. Subsequently, the cooled gas streams 14.1 and 14.2 on the three-way valve 15 for

Total synthesis gas flow SYG summarized. The water vapor mixture in the synthesis gas to be cooled can also be carried out without intermediate cooling of the synthesis gas before the steam mixture.

The steam mixture in the synthesis gas to be cooled to prevent soot formation during cooling is also in a co-electrolysis process for the production of

Synthesis gas feasible.

In order to suppress or prevent soot formation in a co-electrolysis process, as in the RWGS process, steam can be mixed into the synthesis gas to be cooled. To avoid excessive exergy loss, the water vapor should

Process heat to be preheated.

Fig. 5 shows a co-electrolysis process with steam mixing before the gas cooling with preheating of the steam by process heat (Wasserdampfzumischung before the

Synthesis gas cooling with steam preheating (Co-SOC)).

The approximately 850 ° C hot synthesis gas 107 is first cooled in the heat exchanger 101.2 to about 650 to 700 ° C. At this temperature, the gas mixture is not yet in the Rußgebiet. In the intercooled gas mixture 112 steam H ₂ Og.2 is mixed from an external source, which was preheated in the heat exchanger 101.3 against a partial stream 114.2 of the steam-synthesis gas mixture 113.

As a result of the water vapor mixing, the state point of the gas mixture 113 shifts in the direction of water and, during the further cooling in the heat exchangers 101. 1 and 101. 3, only reaches the soot area at a lower temperature. At this temperature, due to the kinetics of the soot formation reactions R1 and R2 and the short residence time of the gas mixture in the heat exchanger no soot is expected.

The second partial stream 114.1 of the steam-synthesis gas mixture 113 is used for the recuperative preheating of the feed gas mixture 100 in the heat exchanger 101.1. The recuperatively cooled synthesis gas streams 115.1 and 115.2 are in the

Final coolers 108.1 and 108.2 further cooled. The resulting condensate 109.1 and 109.2 is discharged.

In the control valve 117, the cooled synthesis gas streams 116.1 and 116.2 are combined again into the total flow SYG.

The water vapor mixture in the synthesis gas to be cooled is also without

Intermediate cooling of the synthesis gas before Dampfeinmischung feasible.

Fig. 6 shows a co-electrolysis process with hydrogen excess mode for

Prevention of soot formation during gas cooling (excess of hydrogen (Co-SOC)). The principle of the hydrogen surplus method can also be applied to an RWGS process (will not be described separately).

In contrast to the co-electrolysis process according to the prior art (FIG. 2), in addition to carbon dioxide C0 ₂ and water vapor H ₂ Og, also circulating hydrogen 118 is mixed to form gas mixture 100. The circulating hydrogen causes the state point of the synthesis gas 107 to be cooled to be displaced in the direction of hydrogen (see FIG. 15), and thus the soot formation during gas cooling in the heat exchanger 101 is suppressed or prevented.

Since the synthesis gas 116 after the final cooling in the radiator 108 too high

Has hydrogen content, the excess hydrogen in a suitable, hydrogen-selective gas separation device 119, for example in a Membrantrennanläge or PSA plant, separated and recycled as hydrogen chloride 118 again with the feed gases H ₂ Og and C0 ₂ fed to the process.

As the separated hydrogen 118 is typically depressurized by the gas separation device 119 and the synthesis gas is supplied to a synthesis which is operated under pressure, the total gas stream 116 is increased in pressure prior to gas separation with the compressor 120. Alternatively, the compressor 120 may also be in the separated hydrogen stream 118.

To control the amount 121 separated in the hydrogen stream 118 and the hydrogen to carbon monoxide molar ratio, which from the in the gas analysis 122 in the

Synthesis gas flow SYG measured H ₂ - and CO concentrations is used, the control valve 123, which leads a bypass flow 124 to the gas separation device 119.

In Fig. 7 is an electrolysis process for the production of synthesis gas from water vapor and carbon dioxide by means of two separate electrolyses for water vapor and

Carbon dioxide shown (separate H ₂ 0 and C0 ₂ electrolysis and quenching of CO rich gas with water). The CO-containing product stream from the C0 ₂ electrolysis is quenched with water and thus rapidly cooled, which suppresses or prevents soot formation during cooling.

Carbon dioxide C0 ₂ is preheated in the heat exchanger 101.3 against the partial flow 126.2 of the hot oxygen-air mixture 110 and then heated in the electric heater 103.2 to an inlet temperature of about 850 ° C in the stack 105.2.

In stack 105.2, the hot carbon dioxide 104.2 is decomposed by means of electric energy 106.2 into carbon monoxide and oxygen. The decomposition of the C0 ₂ is not complete, so that in the exiting gas 107.2 after the stack 105.2 in addition to CO still C0 _{2 is} included. The about 850 ° C hot CO-C0 ₂ mixture 107.2 is cooled in the quencher 127 by injecting water 128 shock. The rapid cooling prevents soot formation. If, however, little soot is formed, it is washed out of the gas by the atomized water and ends up in the quench 127 of the quench, from where it is separated as

Mud water 129 withdrawn and fed to a further treatment.

The quench water also accumulating in the sump passes through an overflow in the subsequent cooler 130. A partial flow of the cooled water 131 is recirculated by means of the pump 132 and fed as quench water 128 to the quencher 127 again. In order to prevent an accumulation of soot in the quench water 128, a portion of the water is discharged as wastewater ABW. The additional water H ₂ Of serves to compensate for water losses in Quenchwasserkreislauf.

The steam H ₂ Og is preheated in the heat exchanger 101.1 against the hot, to be cooled H ₂ - H ₂ 0 mixture 107.1 and then preheated by means of the electric heater 103.1 to inlet temperature of about 850 ° C in the stack 105.1. In the stack 105.1, the electrolytic decomposition of the hot water vapor 104.1 into hydrogen and oxygen takes place with the aid of electric energy 106.1. The decomposition of the water vapor is not complete, so that in the exiting gas 107.1 after the stack 105.1 next to hydrogen nor water vapor is included.

The cooled in the heat exchanger 101.1 H ₂ -H ₂ 0 mixture 133.1 is mixed with the cooled in quencher 127 CO-C0 ₂ mixture 133.2, which is saturated by quenching with water vapor, and fed as a gas mixture 134 operated with cooling water end cooler 108 , After final cooling, the finished synthesis gas SYG reaches the subsequent synthesis. The resulting in the cooling condensate 109 is discharged from the process.

The in the stacks 105.1 and 105.2 electrolytically split off from C0 ₂ and H ₂ 0 oxygen is scavenged air, in the heat exchanger 201 against the second partial flow 126.1 of about 850 ° C hot air-0 ₂ mixture 110, resulting from the Streams 110.1 and 110.2 composed of the stacks 105.1 and 105.2, preheated.

Subsequently, the purge air is divided into stacks 105.1 and 105.2 and heated in the electric heaters 203.1 and 203.2 to an inlet temperature of about 850 ° C.

The cooled in the heat exchangers 201 and 101.3 exhaust gas (air-0 ₂ mixture) is in the control valve 123 temperature regulated (135.1, 135.2) summarized and discharged as a common stream EXG to the environment.

In Fig. 8 is an electrolysis process for the production of synthesis gas from water vapor and carbon dioxide by means of two separate electrolyses for water vapor and

Carbon dioxide (separate H ₂ O and CQ ₂ electrolysis and quenching of the CO containing gas with cold hydrogen). The carbon monoxide-containing product stream from the C0 ₂ - electrolysis is quenched with cooled H ₂ -rich gas from the H ₂ 0 electrolysis and thus cooled rapidly, which suppresses or prevents soot formation during cooling.

Carbon dioxide C0 ₂ is preheated in the heat exchanger 101.3 against the partial flow 126.2 of the hot exhaust gas 110 and then heated in the electric heater 103.2 to an inlet temperature of about 850 ° C in the stack 105.2.

In stack 105.2, the hot carbon dioxide 104.2 is decomposed by means of electric energy 106.2 into carbon monoxide and oxygen. The decomposition of the C0 ₂ is not complete, so that in the exiting gas 107.2 after the stack 105.2 in addition to CO still C0 _{2 is} included.

The about 850 ° C hot CO-C0 ₂ mixture 107.2 is cooled in the gas quencher 136 by mixing cold H ₂ -rich gas 137 shock. The rapid cooling prevents soot formation.

The cooled in the heat exchanger 101.1 H ₂ -H ₂ 0 mixture 138 is cooled as far as possible in operated with cooling water end cooler 108. The resulting

Condensate 109 is removed from the process.

After the mixture of the two gas streams 107.2 and 137 in the gas quencher 136, the gas 139 is cooled in the second cooling cooler 108 operated with cooling water and finished

Synthesis gas SYG supplied to the subsequent synthesis process.

The split off in the stacks 105.1 and 105.2 electrolytically from C0 ₂ and H ₂ 0 oxygen is scavenged air, in the heat exchanger against the second partial flow 126.1 of about 850 ° C hot air-0 ₂ mixture 110 resulting from the streams 110.1 and 110.2 composed of the stacks 105.1 and 105.2, preheated.

The cooled in the heat exchangers 201 and 101.3 exhaust gas (air-0 ₂ mixture) is in the control valve 123 temperature regulated (135.1, 135.2) summarized and discharged as a common stream EXG to the environment. The following describes measures to eliminate soot deposits in heat exchangers for synthesis gas cooling (soot removal).

LIST OF REFERENCE NUMBERS

ABW wastewater

Air purge air

C0 ₂ carbon dioxide

EXG exhaust

H _{2 is} hydrogen

H ₂ Og water vapor

H ₂ Og.2 additional water vapor

H ₂ of water (liquid)

N ₂ purge nitrogen

SPG synthesis purge gas

SYG synthesis gas

I feed gas mixture RWGS

2 recuperator RWGS

2.1 Recuperator for partial cooling of the synthesis gas RWGS

2.2 Recuperator for partial cooling of the synthesis gas RWGS

2.3 Recuperator for partial cooling of the synthesis gas RWGS 3 hot feed gas stream RWGS

4 electric heaters RWGS

5 catalytic reactor RWGS

6 hot syngas RWGS

7 shot coolers RWGS

7.1 Final cooler in the synthesis gas partial flow RWGS

7.2 Final cooler in the synthesis gas partial flow RWGS

8 condensate RWGS

8.1 Condensate from the synthesis gas partial flow RWGS

8.2 Condensate from the synthesis gas stream RWGS

9 Differential pressure measurement RWGS

9.1 Differential pressure measurement in the synthesis gas partial flow RWGS

9.2 Differential pressure measurement in the synthesis gas partial flow RWGS

10 intercooled syngas stream RWGS

I I Synthesis gas-water vapor mixture RWGS

12.1 Partial stream of the synthesis gas-water vapor mixture RWGS 12.2 Partial stream of the synthesis gas-water vapor mixture RWGS

13.1 Cooled synthesis gas stream RWGS 13.2 Cooled synthesis gas partial flow RWGS

14.1 Synthesis gas partial stream downstream of RWGS end cooler

14.2 Synthesis gas partial stream downstream of RWGS final cooler

15 Three-way fitting RWGS

100 feed gas mixture co-electrolysis

101 recuperator co-electrolysis

101.1 Recuperator Co-electrolysis for partial cooling of the synthesis gas

101.2 Recuperator Co-electrolysis for partial cooling of the synthesis gas

101.3 Recuperator co-electrolysis to heat C0 ₂

102 preheated feed gas co-electrolysis

103 Electric heater Feedgas co-electrolysis

103.1 Electric heater Partial flow Feedgas Co-electrolysis

103.2 Electric heater Partial flow Feedgas Co-electrolysis

104 hot feed gas co-electrolysis

104.1 hot partial stream feed gas (C0 ₂ ) co-electrolysis

104.2 hot partial flow of feed gas (H ₂ Og) co-electrolysis

105 Co-electrolysis stack

105.1 Electrolysis stack for H ₂ Og

105.2 Electrolysis stack for C0 ₂

106 Electric energy co-electrolysis

106.1 Electric Energy Electrolysis H ₂ Og

106.2 Electric energy electrolysis C0 ₂

107 hot syngas co-electrolysis

107.1 Partial stream of hot syngas co-electrolysis

107.2 Partial stream of hot syngas co-electrolysis

108 Final Cooler Co-electrolysis

109 condensate co-electrolysis

110 oxygen-air mixture co-electrolysis

110.1 partial flow oxygen-air mixture co-electrolysis

110.2 Partial flow oxygen-air mixture Co-electrolysis

111 Differential pressure measurement Recuperator Co-electrolysis

111.1 Differential pressure measurement in the synthesis gas partial stream Co-electrolysis

111.2 Differential pressure measurement in the synthesis gas partial stream Co-electrolysis

112 intercooled syngas co-electrolysis

113 Synthesis gas-water vapor mixture Co-electrolysis

114.1 Partial stream of the synthesis gas-water vapor mixture Co-electrolysis

114.2 Partial stream of synthesis gas-water vapor mixture Co-electrolysis 115.1 Cooled synthesis gas partial stream Co-electrolysis

115.2 Cooled synthesis gas partial stream Co-electrolysis

116 Synthesis gas stream after final condenser Co-electrolysis

116.1 Synthesis gas partial stream after final cooler Co-electrolysis

116.2 Synthesis gas partial stream after final cooler Co-electrolysis

117 Three-way fitting Co-electrolysis

118 circulating hydrogen

119 gas separation co-electrolysis (e.g., membrane)

120 gas compressor

121 Flow rate measurement

122 gas analysis

123 three-way regulator

124 bypass flow synthesis gas

126.1 Partial flow oxygen-air mixture Co-electrolysis

126.2 Partial flow oxygen-air mixture Co-electrolysis

127 water quenchers co-electrolysis

128 quench water co-electrolysis

129 muddy water

130 cooler quencher co-electrolysis

131 partial flow quench water co-electrolysis

132 pump quench water co-electrolysis

133.1 cooled H ₂ -H ₂ 0 mixture co-electrolysis

133.2 cooled CO-C0 ₂ -mixture co-electrolysis

134 cooled syngas co-electrolysis

135.1 Temperature measurement partial flow of exhaust gas

135.2 Temperature measurement partial flow of exhaust gas

136 Gas quencher co-electrolysis

137 cold, H ₂ -rich gas co-electrolysis

138 cooled, H ₂ -H ₂ 0 mixture co-electrolysis

139 mixed gas after gas quenching co-electrolysis

201 recuperator co-electrolysis, exhaust side

203 electric heater air co-electrolysis

211 Differential pressure measurement anode-cathode stack co-electrolysis

Claims

Soot avoidance and / or Rußverminderungsverfahren within a synthesis gas and / or CO-containing gas generating device from the feed gases

Carbon dioxide, water vapor, hydrogen and / or a

Hydrocarbon residual gas and electric energy in RWGS processes,

Electrolysis for electrochemical decomposition of carbon dioxide and / or

Water vapor, reforming processes and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for performing a RWGS reaction, and at least one cooling line / recuperator for CO-containing gas and / or synthesis gas, characterized that

an additional gas, liquid and / or gas mixture is admixed before the feed into the gas production in the feed gas stream and / or after the gas production in the CO-containing gas / synthesis gas, wherein the additional gas, liquid and / or gas mixture is selected from:

a) water vapor for increasing the water vapor content in the generated gas,

this being introduced after synthesis gas production;

b) hydrogen to increase the hydrogen content in the generated gas, which is introduced into the feed gas stream or after the synthesis gas production;

c) Hydrogen-rich gas for cooling the CO-rich gas stream, wherein this hydrogen-rich gas is externally provided or produced by separate C0 ₂ - and H ₂ 0 electrolysis, and mixed the hydrogen-rich gas in the CO-rich gas stream is, wherein the hydrogen-rich gas is recuperatively cooled against heated water vapor and / or C0 ₂ stream when prepared via the separate electrolysis process prior to mixing;

and or

d) water to cool the CO-containing gas stream before a

Hydrogen interference. Soot avoidance and / or soot reduction arrangement with a

A soot avoidance and / or soot reduction process according to the preceding claim, at or within a synthesis gas and / or CO-containing gas producing device from the feed gases carbon dioxide, water vapor, hydrogen and / or a hydrocarbonaceous residual gas and electric energy in RWGS processes, electrochemical electrochemicals Disassembly of Carbon dioxide and / or steam, reforming operations and / or synthesis gas production processes with at least one gas generating unit, an electrolysis stack and / or a heater-reactor combination for

Performing an RWGS reaction, and at least one cooling / recuperator for CO-containing gas and / or synthesis gas,

characterized in that

an additional gas, liquid and / or gas mixture supply is provided before feeding into the gas production in the feed gas stream and / or after gas production in the CO-containing gas / synthesis gas, wherein by this supply water vapor, hydrogen, hydrogen-rich gas an external supply device, hydrogen-rich gas from a separate C0 ₂ - and H ₂ 0 electrolysis and / or water are supplied.