EP3288891A1

EP3288891A1 - Apparatus and method for producing a synthesis gas

Info

Publication number: EP3288891A1
Application number: EP16722103.5A
Authority: EP
Inventors: Olaf Kühl
Original assignee: Ccp Technology GmbH
Current assignee: CAPHENIA GMBH
Priority date: 2015-04-30
Filing date: 2016-04-29
Publication date: 2018-03-07
Also published as: DE102015005610A1; WO2016174207A1; US10906806B2; US20180230008A1; CA2984551A1

Abstract

The apparatus described here has a first reaction space with an inlet for a medium composed of hydrocarbon, especially a gas having the composition C_nH_m, and an outlet. In the first reaction space, means of splitting the hydrocarbon with supply of heat into carbon particles and hydrogen are provided between the inlet and the outlet. The apparatus also has a second reaction space having an elongated configuration with a first inlet at one end and an outlet at the opposite end, wherein the first inlet of the second reaction space is connected to the outlet of the first reaction space, and wherein the second reaction space has an increasing flow cross section between the inlet and the outlet (measured at right angles to the longitudinal extent of the second reaction space). Also provided is at least one second inlet into the second reaction space, wherein the second inlet can be connected to a source for CO₂ and/or H₂O. Preferably, the second inlet is connected to a source for CO₂, and hence CO₂ is passed through it in operation. A method of operation for the purpose is likewise described. The apparatus and the method of operation can be used to improve the energy balance of synthesis gas production compared to known methods.

Description

DEVICE AND METHOD FOR PRODUCING A

SYMTHF FOR CCC

The following invention relates to an apparatus and method for generating a synthesis gas.

DE 10 2012 015 314 A1, which is assigned to the assignee of the present application, describes, inter alia, both an apparatus and a method for producing a synthesis gas. In the process disclosed therein, first of all a medium of hydrocarbon is split under the application of heat, in particular by a plasma. This splitting takes place in a first reaction space. A resulting aerosol of carbon particles and hydrogen is fed without substantial cooling a second reaction chamber, in addition C0 _{2 is} introduced. In the second reaction space, which is described for example as a simple tube, there is a conversion of the carbon particles and the C0 ₂ in carbon monoxide (CO). According to DE 10 2012 015 314 A1, a stoichiometric ratio of carbon particles and CO ₂ in the second reaction space should preferably be provided here, which is furthermore preferably maintained at a temperature of approximately 1000 ° C. in order to determine the conversion, which represents an equilibrium reaction. to move in the direction of the CO. Thus, the CO exiting from the second reaction space usually has a temperature of over 800 ° C, and the temperature is usually 800 ° C to 1000 ° C. The invention has for its object to improve the energy balance of a corresponding synthesis gas production and optionally allow a lower temperature at the end of the conversion of the carbon particles into carbon monoxide.

According to the invention, a device for producing a synthesis gas according to claim 1 and a method for producing a synthesis gas according to claim 12 are provided for this purpose.

In particular, the device has a first reaction space with an inlet for a medium of hydrocarbon, in particular a gas with the composition C _n Hn>, and an outlet. In the first reaction space, means are provided between the inlet and the outlet for splitting the hydrocarbon by supplying heat into the carbon particles and hydrogen. The device also has a second one A reaction space having an elongated configuration with a first inlet at one end and an outlet at the opposite end, wherein the first inlet of the second reaction space communicates with the outlet of the first reaction space, and wherein the second reaction space is located between the inlet and having the outlet increasing flow cross-section (measured perpendicular to the longitudinal extent of the second reaction space). Furthermore, at least one second inlet is provided in the second reaction space, wherein the second inlet can be connected to a source for C0 ₂ and / or H ₂ 0. Preferably, the second inlet is connected to a source of CO ₂ , and thus C0 ₂ is introduced thereover in operation.

This configuration allows carbon particles leaving the first high temperature reaction space to first react with C0 _{2 in} accordance with the Boudouard reaction and / or to convert the carbon particles to CO and H ₂ 0 by a heterogeneous water gas shift reaction H _{2 can} react. By a progressive conversion of carbon particles with corresponding C0 ₂ and / or H ₂ 0 gases, a larger volume of CO or synthesis gas (ie CO and H ₂ ) is formed. Due to the widening second reaction space, the increasing volume of CO or synthesis gas can be absorbed. In this way, a pressure increase within the second reaction space can be counteracted. Therefore, a corresponding conversion reaction (ie Boudouard reaction or heterogeneous water gas shift reaction) does not have to work against an increased pressure increase.

In one embodiment and further at least a third inlet is provided in the second reaction space, which is connectable to a source of H ₂ 0-steam and / or C0 ₂ . The second inlet is located in the longitudinal direction of the second reaction space preferably between the first inlet and the third inlet. Preferably, the third inlet is connected to a source of H ₂ O, and thus H ₂ O is introduced thereover. In this configuration, carbon particles not reacted with the C0 _{2 can} then be converted to CO and hydrogen with H ₂ O vapor according to the known heterogeneous water gas shift reaction (also known as hetWGS reaction). The Boudouard reaction is slower compared to the hetWGS and usually requires higher temperatures as well; so that the Boudouard reaction can take place upstream of a hetWGS in the flow direction of the reacting substances or reactants. The sequence of a Boudouard reaction and a hetWGS reaction also makes it possible for the synthesis gas leaving the second reaction space to have a lower temperature than is the case, for example, in the process according to the abovementioned DE 10 2012 015 314 A1 is. Among other things, this results from the fact that the hetWGS reaction also still at lower temperatures is possible. Instead of the staggering of the introduction of the reactants, ie C0 ₂ upstream with respect to the H ₂ O vapor, it is also possible (a) to introduce these two reactants simultaneously via the second inlet, or also (b) the H ₂ O- To introduce steam upstream of the C0 ₂ , even if the stocking as stated above is preferred.

According to one embodiment of the invention, the second process space at the outlet end has a flow cross-section which is larger by at least 20% than at the inlet end. This takes account of an increase in the volume during the conversion of the carbon particles with the corresponding gases C0 ₂ and / or H ₂ O. Advantageously, the second reaction space between the inlet and the outlet has no significant reduction in the flow cross-section. A substantial reduction in the flow cross-section of, for example, more than 5% would result in the desired effect not being fully achieved. A substantial reduction in the flow cross-section would slow down the increasing volume of CO or synthesis gas and lead to an undesirable increase in pressure. In particular, the second reaction space can expand conically in order to provide a continuous, uniform increase in the flow cross section. However, it would also be possible to provide a stepped increase or, for example, two different conical extensions. For example, a first conical extension may be provided downstream of the second inlet, and a second conical extension with a different cone angle may be added downstream of the third inlet for optionally increasing the volume of the hetWGS reaction more rapidly. The flow cross-section may remain the same over a small area (less than about 10%) compared to the length, for example to mount the second and third inlets or sensors.

The means for splitting the hydrocarbon are preferably suitable for heating the carbon particles formed during the decomposition and the hydrogen such that they have a temperature of greater than 1200 ° C., in particular greater than 1600 ° C., at the first inlet of the second reaction space. As a result, the energy required for the conversion can be provided primarily by the carbon particles.

In order to provide a good utilization of the length of the second reaction space, the at least one second inlet lies in the second reaction space with respect to the longitudinal extent of the second reaction space and starting from the first inlet in the first third, in particular in the first quarter. Preferably, the at least one second inlet is located as close as possible to the first inlet of the second reaction space. Moreover, to allow sufficient time for a Boudouard reaction between the CO ₂ and the carbon particles, the at least one third inlet in the second reaction space is located with respect to the longitudinal extent of the second reaction space and again from the first inlet in the second half , especially in the last third. It is considered that the Boudouard reaction is much slower compared to the hetWGS reaction. Therefore, it is also possible to introduce the steam via the at least one third inlet only shortly before the end of the second reaction space. This is particularly advantageous for the variant in which C0 _{2 is introduced} via the second inlet.

Thus, the C0 _{2 should} therefore be introduced as close as possible to the inlet of the second reaction space, while the steam is introduced so far at the end of the second reaction space that there is just enough time left for a conversion of remaining carbon particles according to the hetWGS reaction and possibly further Boudouard reactions perform.

For a good distribution of the process gases, a plurality of second or third inlets is preferably provided, which are spaced apart at least in the longitudinal extent of the second reaction space. In particular, however, a plurality of second or third inlets may also be provided in the circumferential direction, which are also aligned, for example, so that they are not centered on the second reaction space, but introduce gas in the circumferential direction. As a result, good mixing and turbulence of the constituents can be achieved.

In one embodiment, at least one heating unit is provided, which is suitable for heating the second reaction space, and which is arranged in the longitudinal extent of the second reaction space between the at least one second inlet and the at least one third inlet.

The Boudouard reaction is an endothermic reaction such that the temperature drops along the second reaction space (starting from the first inlet). However, in order not to drop the temperature below a certain value, the area lying between the at least one second inlet and the at least one third inlet can be actively heated. According to a further embodiment, at least one heating unit is provided for heating C0 ₂ or H ₂ 0 before entering the second reaction space via the second or third inlet, wherein the heating unit is suitable, the corresponding medium (C0 ₂ or H ₂ 0) to heat a temperature of at least 1000 ° C. Corresponding heating of the media ensures a sufficient temperature for the corresponding reactions. In addition, a corresponding heating also allow a lower inlet temperature of carbon particles and hydrogen.

According to the method for producing a synthesis gas, a medium of hydrocarbon, in particular a gas having a composition C _n H _m , is first split into carbon particles and hydrogen in a first reaction space while supplying heat. Subsequently, at least the carbon particles, but preferably an aerosol of carbon particles and hydrogen, are introduced into a second reaction space having an elongated configuration with a first inlet at one end and an outlet at the opposite end. In this case, the first inlet of the second reaction space communicates with an outlet of the first reaction space, and the second reaction space has a flow cross section which increases between the first inlet and the outlet. Further, C0 ₂ and / or H ₂ 0 are introduced into the second reaction space and adjacent to the inlet end of the second reaction space, ie in a region closer to the inlet end than at the outlet end, at least the carbon particles with C0 ₂ and / or H ₂ 0th to mix. In this case, the mixture of carbon particles (optionally with hydrogen) and C0 ₂ and / or H ₂ O initially has a temperature of at least 1000 ° C., preferably of at least 1400 ° C. If only C0 _{2 is} introduced, at least part of the carbon particles and the C0 ₂ in this mixture is converted into CO according to the Boudouard reaction. When only H ₂ O is introduced, at least a portion of the carbon particles and H ₂ O are converted into synthesis gas according to the heterogeneous water gas shift reaction. When C0 ₂ and H ₂ 0 are introduced, the Boudouard reaction and the heterogeneous water gas shift reaction occur.

By a corresponding extension of the second reaction space, volume-induced pressure increases are prevented or at least reduced so as not to counteract the reaction of the carbon particles with the respective gases. In a preferred embodiment, C0 _{2 is} introduced first at a location near the first inlet, and then H ₂ 0 vapor is introduced into the second reaction space downstream of the C0 ₂ inlet, and at least a portion of the remaining carbon is introduced. The hydrogen particles and the H ₂ O vapor are converted into CO and H ₂ according to the hetWGS reaction. Such a two-stage introduction of C0 ₂ and H ₂ 0 steam, especially when they are in excess, allow a good and substantially complete conversion of the carbon particles and a reduced outlet temperature at the outlet of the second reaction space. This can be, for example, 500-600 ° C.

According to one embodiment of the invention, the carbon particles formed during the decomposition and the hydrogen are introduced jointly as aerosol and at a temperature of greater than 1200 ° C., in particular greater than 1400 ° C., into the second reaction space. This eliminates the one hand, a separation of carbon particles and hydrogen, and moreover, the high temperature of the carbon particles ensures that a sufficient temperature for the reaction is available. It should be noted that the carbon particles are formed from a large number of carbon atoms, which are freed from the surface by the reaction with C0 ₂ from outside carbon atoms. In this process, heat is supplied to the carbon particle while the resulting CO cools. Therefore, the carbon particles can maintain a high temperature over their temperature level over wide areas of the second reaction space over which they release external carbon atoms. Even if a total cooling occurs, the temperature of the carbon particles can be kept sufficiently high even with progressive degradation reaction, so that they can even react towards the end of the reaction with colder C0 ₂ or H ₂ 0. Therefore, it may be advantageous to start with a relatively high temperature of the aerosol. The hydrogen is also available according to the hydrocarbon feedstock for the CO / H ₂ ratio of the synthesis gas.

Based on the longitudinal extent of the second reaction space, the introduction of C0 ₂ and / or H ₂ 0, starting from the first inlet preferably takes place in the first third, in particular in the first quarter. In particular, when introducing C0 ₂ alone, the C0 ₂ should be introduced as close as possible to the first inlet in order to ensure sufficient running time for the Boudouard

Provide reaction. Alternatively, an introduction by in the longitudinal extent of the second reaction space spaced inlets may be advantageous in order to achieve a good mixing of the reactants (carbon particles and C0 ₂ ). Preferably, the amount of introduced C0 _{2 is} controlled based on the amount of previously generated carbon particles. Assuming that the introduced C0 _{2 is} completely or even converted to a certain percentage, can be adjusted as a lot of carbon particles are available for reaction with H ₂ O vapor. In this way, in turn, the hydrogen content in the synthesis gas can be adjusted, on the one hand, the hydrogen from the splitting in the first reaction space and the hydrogen by the reaction according to the hetWGS reaction is considered.

In order to ensure a good conversion of the C0 ₂ according to the Boudouard reaction, the second reaction space can be heated at least in a region which lies in the longitudinal extent of the second reaction space between the introduction of C0 ₂ and the introduction of H ₂ 0 vapor. In this case, the second reaction space is preferably heated to at least 800 ° C. But a corresponding heating can also be omitted if, for example, the carbon particles (possibly mixed with H ₂ ) and the C0 _{2 have} a sufficiently high inlet temperature in the second reaction space.

According to a further embodiment, it is provided that at least one of the following: C0 ₂ and the H ₂ 0 vapor is heated to a temperature of at least 1000 ° C., preferably of at least 1400 ° C., before it enters the second reaction space.

In the above, devices have been described in which the second reaction space has a flow cross-section which increases between the inlet and the outlet (measured perpendicular to the longitudinal extent of the second reaction space). The above-described methods were also carried out with a second reaction space having a larger flow cross-section. However, it is also considered an alternative device in which the second reaction space has any other shape, in particular a constant flow cross-section. The second reaction space has a second and a third inlet in this alternative device. The second

Inlet may be connected to a source for at least C0 ₂ , and the third inlet may be connected to a source of H ₂ 0. The second and third inlets are arranged as described above. In operation, CO ₂ (and optionally a small amount of H ₂ O) is introduced through the second inlet, and H ₂ O is introduced downstream thereof through the third inlet. All other features of the apparatus and method are the same as described above. This alternative apparatus and method also improves the energy balance of syngas production and allows for a lower temperature at the end of the conversion of carbon particles to carbon monoxide. In addition, the composition of the synthesized syngas generated can be easily controlled by controlling the amount of C0 _{2 introduced} . The invention will be explained in more detail with reference to the drawings; in the drawings shows:

Figure 1 is a schematic cross-sectional view through an apparatus for generating a synthesis gas;

Figure 2 is a schematic cross-sectional view along the line II-II in Figure 1;

Figure 3 is a schematic detail view in section of introduction areas for

Process gases.

Terms used in the description, such as top, bottom, left and right, refer to the representation in the drawings and are not limiting. But you can describe preferred versions. The words "substantially" and similar phrases referring to parallel, perpendicular or angular terms shall include deviations of + 3 degrees and shall include deviations of 5% based on other data and quantities.

In the following, a schematic structure of a device 1 for producing a synthesis gas will be explained in more detail with reference to FIGS. 1 to 3, wherein FIG. 1 shows a schematic sectional view of the device 1 for producing a synthesis gas. Figure 2 shows a schematic sectional view through the device 1 along the line II-II in Figure 1, wherein a special gas introduction configuration is shown, which does not match the representation of FIG. FIG. 3 shows an enlarged partial sectional view of various embodiments of a gas introduction region of the device 1.

The device 1 consists essentially of a first reaction space 3, which is surrounded by an insulating housing 5, and a second reaction space 7, which is surrounded by an insulating housing 9.

In the housing 5 surrounding the first reaction space 3, a multiplicity of first inlets 10 and a multiplicity of second inlets 12 are formed. The inlets 10 and 12 are each provided in an upper wall of the housing 5. The inlets 10 are arranged on a first imaginary circular line and the inlets 12 are arranged on a second imaginary circular line. The two circles are concentric with each other. However, it is also possible to provide a different arrangement of the first and second inlets 10, 12. In particular, it is also possible to provide only one, for example, circumferential inlet 10 or a circumferential inlet 12. The inlets 12 are arranged with respect to the inlets lying inside. The housing 5 has fei ner an underlying outlet opening 13. As can be seen in Figure 1, the housing 5 may provide the same in the lower region of the reaction chamber 3 a taper. But it is also possible that a corresponding taper is not provided, and the housing 5 in section, essentially describes an upside-down U-shape.

In the interior of the reaction space 3, two annular, concentrically arranged electrodes 14, 15 are arranged, which are connectable via supply line elements, not shown, with a power source. In this case, the electrode 14 lies concentrically within the electrode 15. The electrodes 14, 15 are fastened to an upper wall of the housing 5 in such a manner that they extend downwards. The inlets 12 are aligned with the electrodes 14, 15 so as to open into the space between the electrodes 14, 15. The outlet openings 10 are aligned with respect to the electrodes 14, 15 so that they open to a region between the outer electrode 15 and a side wall of the housing 5. Alternatively, rod-shaped electrodes can be used.

The second inlets 12 are suitably connected to a gas source for introducing a plasma gas. As plasma gas, any suitable gas can be selected, which is supplied from the outside or produced in the hydrocarbon converter. As plasma gas, for example inert gases are suitable, for example argon or nitrogen. On the other hand, hydrogen gas H ₂ , CO or synthesis gas offer, since these gases are incurred anyway in the operation of the device described here. The electrodes 14, 15 and the current source connected thereto are matched to one another such that when a voltage is applied between the electrodes 14, 15 and a plasma gas is introduced via the second inlets 12, a plasma can be ignited and maintained between the electrodes. In particular, the vote can be made such that a plasma also burns beyond the free ends of the electrodes 14, 15 out. The inlets 10 are in turn connected to the source of a medium of hydrocarbon, in particular a gas having a composition C _n H _m in combination. The medium introduced via the inlets 10 essentially forms a media curtain or layer of flowing gas between the outer electrode 15 and the sidewall of the housing 5 to protect the sidewall from high temperatures generated by the plasma. In addition, the medium also absorbs heat to be split on its way from the second inlet 10 in the direction of the lower outlet 13 of the housing 5 by the heat supply and the plasma into its constituents. That is, the medium introduced via the inlet 10 is split into carbon particles and hydrogen as it exits the outlet 13 of the first reaction space. The second reaction space 7 has a substantially tubular shape, which widens conically from a first end adjacent to the first reaction space 3 to a second end. The second reaction space 7 is bounded by the housing 9, which specifies a corresponding conically widening shape in the circumferential direction. However, a corresponding extension can also be carried out stepwise or in another way continuously or discontinuously. The reaction space 7 thus has a first inlet 20, which essentially corresponds in shape and in the flow cross-section to the outlet 13 of the first reaction space 3 and lies directly adjacent thereto. At the opposite end, a corresponding outlet 22 is formed. The second reaction space 7 has no or at least no substantial reduction of the flow cross-section between the inlet 20 and the outlet 22, so that the volume of CO or synthesis gas flowing through is not braked. The flow cross-section can remain the same over a small area (less than about 10%) compared to the length, for example to mount inlets, outlets or sensors. However, an insignificant reduction in the flow cross-section is not detrimental and should also be included in this disclosure. Such an insignificant reduction may, for example, result in the design when an outlet flange or fitting is to be attached to the end of the second reaction space 7.

A plurality of second gas inlets 24 and third gas inlets 26 are formed in the insulating housing 9, which has a corresponding, conically widening tubular shape.

The second gas inlets 24 are located substantially directly adjacent to the first inlet 20 of the reaction space 7, preferably in the longitudinal extent of the second reaction space and starting from the first inlet 20 in the first third, in particular in the first quarter. The second gas inlets 24 may be directed radially inwards on a longitudinal axis of the reaction space 7 or also extend into the reaction space 7 at an angle, as indicated in FIG. A corresponding angled introduction, as shown in FIG. 2, causes gas introduced via the second inlet 24 to effect a circular flow component (perpendicular to the longitudinal extent) within the first reaction space 7. The second inlets 24 communicate with a source of CO ₂ gas. In particular, the source of CO ₂ gas may be waste gases from an industrial process. The corresponding exhaust gases may have been previously cleaned and / or filtered in order to provide as pure C0 ₂ as possible. For example, the C0 _{2 can} also be frozen out of a corresponding exhaust gas flow, whereby water is usually frozen out with it, so that not only CO ₂ but also water can be introduced via the second inlets 24.

The second inlets 24 may be surrounded in a supply region by a heating sleeve 30, which is suitable for heating the medium supplied via the corresponding second inlet 24 to a predetermined temperature. In particular, it is contemplated to heat via the second inlet 24 initiated C0 ₂ (and possibly water) to a temperature of about 1000 ° C. The heating sleeve 30 should be designed accordingly. But it is also possible instead of a heating jacket 30 to provide another heating unit, which can ensure a corresponding preheating. It is contemplated to heat the C0 ₂ (and possibly water) with waste heat from the first reaction space 3. Thus, the housing 5 of the first reaction chamber 3 can be protected against overheating. The third inlets 26 are located farther from the inlet 20 of the reaction space 7 than the second inlets 24 in the longitudinal direction of the reaction space. In particular, the third inlets 26 are located in a second half and in particular in a last third of the reaction space 7 relative to the longitudinal direction of the reaction space 7 The third inlets 26 may have substantially the same configuration as the second inlets 24 and may in turn include a heating collar 30 to facilitate preheating a medium introduced thereinto. The third inlets 26 communicate with a source of water or water vapor, respectively.

In a region between the second inlets 24 and the third inlets 26, a heating unit 34 facing the second reaction space 7 is provided in the insulating housing 9. This is designed so that it can heat the reaction space 7 and reactants contained therein at a temperature of at least 800 ° C., preferably 1000 ° C., or at a corresponding temperature. Although a plurality of in-plane second and third inlets 24 and 26 are shown in each of FIGS. 1 and 2, it is also possible to provide only a single inlet, which may have different shapes. Also it is possible, as in Figure 3 is indicated to provide a plurality of spaced apart in the longitudinal direction of the reaction chamber 7 second inlet 24 or third inlets 26. In this case, the inlets 24, 26 accommodate different shapes, in Figure 3, two different shapes are indicated. In the overhead mold three in the longitudinal direction of the reaction chamber 7 spaced inlets 24 and 26 are provided, each having its own supply line with heating jacket 30, if necessary.

In the embodiment below, only one supply line with heating jacket 30 is provided, and the inlets 24 and 26, which are spaced apart in the longitudinal direction of the second reaction space, are formed through a side wall of the housing 9 through an angled bore.

The operation of the device 1 will now be explained in more detail with reference to the figures.

Via the second inlets 12 to the first reaction space 3, a plasma gas, such as argon, nitrogen, hydrogen gas H ₂ , CO or synthesis gas, is introduced into the space between the ring electrodes 14, 15. Between the electrodes 14, 15, a voltage is applied so that the plasma gas ignites and a plasma is generated. The plasma burns in the gap between the electrodes 14, 15 and beyond their free ends.

For example, a methane gas (CH ₄ ) is introduced into the annular space between the outer electrode 15 and the side wall of the housing 5 via the first inlets 10 in the reaction space 3. The methane gas heats up in its flow in the direction of the outlet 13 of the first reaction chamber 3. It is heated so much that it splits into its constituents carbon and hydrogen. These form an aerosol which exits from the outlet 13 of the first reaction space 3. This aerosol also contains components of the plasma gas, which are neglected in the following.

The supply of the plasma gas, the voltage between the electrodes 14, 15 and the supply of methane are coordinated so that the methane is completely split, and the corresponding generated aerosol of carbon and hydrogen at its exit from the outlet 13 of the first reaction chamber. 3 a temperature of greater than 1000 ° C, in particular over 1200 ° C preferably above 1400 ° C has. Furthermore, the process conditions are coordinated so that the resulting carbon particles size as possible in the range 1 -500 nm, in particular from 5 to 200 nm and preferably from 10 to 100 nm. These can be present as individual particles or as clusters which disintegrate into individual particles shortly after the beginning of a reaction. The aerosol enters the second reaction chamber 7 via the inlet 20 and is there mixed with C0 ₂ which is introduced via the second inlet 24 into the second reaction chamber 7, mixed. In this case, the temperature of the C0 _{2 is} adjusted to the aerosol temperature, class, the mixture has at least a temperature of 1000 ° C, preferably of at least 1200 ° C. In the corresponding mixture, the carbon particles in the aerosol are converted to CO (carbon monoxide) by reaction with the CO ₂ . For the carbon particles, which initially release carbon atoms on their surface, the process causes heat to be supplied to the carbon particles. On the other hand, the CO ₂ gas cools down to CO at the corresponding conversion. Corresponding conversion of carbon particles and C0 ₂ to CO is also known as the Boudouard reaction (C0 ₂ + C -> 2 CO). The reaction proceeds while the reactants involved in the reaction flow along the second reaction space 7. Optionally, the area downstream of the second inlets 24 may be maintained at a predetermined temperature level via the heating unit 34.

The feed of C0 ₂ via the second inlets 24 is preferably controlled so as to convert all or a certain percentage of C0 ₂ , but not all of the carbon particles. In other words, C0 ₂ can be supplied substoichiometrically.

Via the third inlets 26, steam (H ₂ O vapor) is introduced into the second reaction space 7 downstream of the second inlet 24. The water vapor as well as remaining C0 ₂ reacts with the remaining carbon particles. The reaction of carbon particles and the H ₂ 0 vapor is carried out according to the so-called heterogeneous Watergas shift reaction (hetWGS reaction). This reaction is much faster than the Boudouard reaction and can also take place at lower temperatures, with the temperature preferably above 550 ° C.

Here, a substantially complete implementation of the carbon particle is sought. At the outlet 22 of the second reaction space 7, the carbon particles should thus be substantially completely reacted, wherein "substantially" is intended to include a conversion of at least 90%, preferably of at least 95%. Thus occurs at the outlet 22 a synthesis gas as a mixture of CO and hydrogen, wherein in the synthesis gas also also C0 ₂ and water vapor and possibly smaller unreacted carbon particles may be present. Overall, the supply of the corresponding reactants should be selected so that the unreacted constituents are below predetermined thresholds, not to preclude further processing in subsequent processes, such as a Fischer-Tropsch synthesis. A corresponding regulation can be made by the person skilled in the art within the scope of the above disclosure. As described above, the second reaction space 7 has a conical pipe shape expanding from the first inlet 20 to the outlet 22. The shape is selected such that the outlet end has a cross section approximately at least 20% larger than the inlet end. Preferably, the increase in the flow cross-section is between 20 and 25%.

While previously a process of a process has been described with reference to the figures, further considerations on which the present invention is based are set forth below. The basic equation of the conversion reaction in the second reaction space starting from CH ₄ as input gas in the first reaction space 3 is:

3 C + 6 H ₂ + C0 ₂ + 2 H ₂ O = 4 CO + 8 H ₂ ,

in which case a stoichiometric ratio of the reactants in a specific ratio to each other is assumed.

The reaction thus takes place with a doubling of the number of particles and is also endothermic. From the general gas equation p V = n R T therefore follows an increase in pressure in a closed system, starting from a constant temperature, which can be kept constant, for example via an external heater.

If one waives the external heating, the temperature decreases in the course of the reaction along the second reaction space and the pressure increase is flatter. Due to the conical widening of the second reaction space, an increase in pressure despite an increase in volume can essentially be avoided or at least reduced, so that the reaction must work less against an external pressure. In the present system, a constant temperature maintenance in the second reaction space 7 dispensed with, although an additional heating can optionally be provided via the heating unit 34 in an intermediate region.

Due to the conical design of the second reaction space 7, a volume increase, which can not be compensated by the decrease in temperature along the second reaction space 7, is at least partially absorbed.

Two specific examples of a process sequence will now be given below, wherein 3 methane (CH ₄ ) is used as the input gas for the first reaction chamber. The temperature of the resulting by the decomposition of CH ₄ aerosol at the outlet 13 is 2100 ° C, and the temperature of the synthesis gas at the outlet is 1000 ° C. In a first stage of the second reaction space 7, ie between the inlet 20 and the inlets 26, 600 units of the aerosol (of carbon particles and hydrogen) with 100 units of C0 ₂ (1600 ° C) are converted to 800 units of fluid. The temperature drops from 2100 ° C to 1660 ° C. In a second stage, ie downstream of the inlet 26, 800 units of the fluid are then reacted with 200 units of steam (1600 ° C) to 1200 units of synthesis gas. The temperature drops from 1660 ° C to 1000 ° C. This results in:

Stage I: AT = -1/6 AV = +1/3 Δρ

Stage II: AT = -1/3 AV = +1/2 Ap

Total: AT = -1/2 AV = +1 Ap where AT is the temperature decrease, AV is the volume increase, and AP is the pressure increase.

In a second example, the temperature of the aerosol is 1600 ° C and the temperature of the exiting syngas is 500 ° C. In the first stage, 600 units of aerosol with 100 units of C0 ₂ (1600 ° C) are converted to 800 units of fluid. The temperature drops from 1600 ° C to 1080 ° C. In the second stage, 800 units of the fluid are mixed with 200 units of water vapor (1600 ° C) to form 1200 units of synthesis gas. The temperature drops from 1080 ° C to 500 ° C. It follows:

Stage I: AT = -1/4 AV = +1/3 Ap = +1/12

Stage II: AT = -2/5 AV = +1/2 Δρ = +1/10

Total: AT = -3/5 AV = +1 Ap = +2/5 At a lower initial temperature of the aerosol and thus at the same time a lower starting temperature of the synthesis gas so also to be compensated pressure increase is lower. The necessary expansion of the tube results from the equation for the cross-sectional area A = π r ² as factor 1, 18 (for p ₂ = 1, 4 p,) and factor 1, 22 (for p ₂ =

By compensating for the increase in volume, the principle of Le Chatelier is overridden and the reaction no longer has to work against the external pressure.

As a result of the process control described above, it is possible to dispense with heating the first reaction space 7 to a constant temperature, although additional heating for an intermediate area may be advantageous. As a result, the exit temperature of the synthesis gas can be brought below 500 ° C and is no longer at 800 -

1000 ° C, as in a classic Boudouard reactor, as mentioned in the prior art. It is saved corresponding heating energy.

The reaction gases C0 ₂ and H ₂ 0 can be stoichiometrically introduced with respect to the introduced carbon particles, but both (together) are preferably used in excess 10 - 30%. If necessary, the unreacted reaction gases can be re-frozen after the reaction in order to be reintroduced into the second reaction space, if necessary. Even if a part of the syngas is also frozen out, it is not lost. Residues of C0 ₂ and H ₂ 0 in the synthesis gas do not interfere with further processing, for example in a Fischer-Tropsch process, provided that certain limit values are met.

An excess of carbon particles, on the other hand, would be at the expense of the synthesis gas yield and is therefore not economical. Therefore, it is preferable to work with an excess of C0 ₂ and / or H ₂ 0.

The H ₂ / CO ratio of the synthesis gas can be regulated by changing the amount of C0 ₂ added based on the amount of the introduced carbon particles. The more C0 ₂ is supplied, the lower the relative H ₂ content in the synthesis gas and the higher the amount of CO. The reaction gases C0 ₂ and H ₂ 0 can be heated prior to their introduction into the second reaction space. Heating to a temperature range between 1400 and 1600 ° C is considered. As a result, the exit temperature of the aerosol at the outlet of the first reaction space can be reduced, for example to a temperature range between 200 and 1400 ° C.

The invention has been explained in detail above with reference to a specific embodiment, without being limited to the specific embodiment. In particular, the construction of the first reaction space may differ from that shown. In particular, the design, arrangement and number of electrodes may change, as well as the inlet for hydrocarbons be arranged differently. Furthermore, it is not necessary for the decomposition of the starting material to take place by means of a plasma. Also, the arrangement and the number of second and third inlets to the second reaction space may differ from the illustrated arrangement and number.

As mentioned above, it is also considered that the second reaction space has any other shape, in particular a constant flow area. In this alternative device, the second reaction space has second and third inlets arranged as described above. In operation, CO ₂ (and optionally a small amount of H ₂ O) is introduced through the second inlet, and H ₂ O is introduced downstream thereof through the third inlet. All other features of the device and method are the same as described above.

Claims

claims

1 . Apparatus for producing a synthesis gas, comprising:

a first reaction space having an inlet for a medium of hydrocarbon, in particular a gas having the composition C _n H _m , and an outlet; Means for cracking the hydrocarbon by applying heat to carbon particles and hydrogen disposed in the first reaction space between the inlet and the outlet;

a second reaction space having an elongated configuration with a first inlet at one end and an outlet at the opposite end, the first inlet of the second reaction space communicating with the outlet of the first reaction space and the second reaction space communicating between the inlet and the second reaction space Outlet increasing flow cross-section;

at least one second inlet into the second reaction space, wherein the second inlet is connectable to a source of C0 ₂ and / or H ₂ 0.

2. Apparatus according to claim 1, wherein the apparatus comprises at least a third inlet into the second reaction space, which is connectable to a source of H ₂ 0-steam and / or C0 ₂ .

3. The apparatus of claim 2, wherein the second inlet is arranged in the longitudinal direction of the second reaction space between the first inlet and the third inlet.

4. Device according to one of the preceding claims, wherein the second reaction space at the outlet end has a flow cross-section which is larger by at least 20% than at the inlet end.

5. Device according to one of the preceding claims, wherein the second reaction space between the inlet and the outlet has no significant reduction of the flow cross-section.

6. Device according to one of the preceding claims, wherein the second reaction space widens conically.

7. Device according to one of the preceding claims, wherein the means are suitable for splitting the hydrocarbon, which arise during the splitting- To heat the carbon particles and the hydrogen so that they have a temperature of greater than 1200 ° C, in particular greater than 1400 ° C at the first inlet of the second reaction space.

8. Device according to one of the preceding claims, wherein the at least one second inlet in the second reaction space with respect to the longitudinal extension of the second reaction space, starting from the first inlet in the first third, in particular in the first quarter, is arranged.

9. Device according to one of the preceding claims, wherein the at least one third inlet in the second reaction space with respect to the longitudinal extent of the second reaction space and starting from the first inlet in the second half, in particular in the last third, is arranged.

10. Device according to one of the preceding claims, wherein a plurality of second and / or third inlets is provided which are spaced apart at least in the longitudinal extent of the second reaction space.

1 1. Device according to one of the preceding claims, which has at least one heating unit which is suitable for heating the second reaction space and which is arranged in the longitudinal extent of the second reaction space between the at least one second inlet and the at least one third inlet.

12. Device according to one of the preceding claims, comprising at least one heating unit for heating C0 ₂ or H ₂ 0 before entering the second reaction space via the second or third inlet, wherein the heating unit is adapted to the corresponding medium to a temperature of to heat at least 1000 ° C.

13. A process for producing a synthesis gas, comprising the following steps:

Splitting a medium of hydrocarbon, in particular a gas having the composition C _n H _m , in a first reaction space while supplying heat into carbon particles and hydrogen;

At least the carbon particles pass into a second reaction space having an elongated configuration with a first inlet at one end and an outlet at the opposite end, the first inlet of the second reaction space communicating with an outlet of the first reaction space, and wherein the second reaction space between the inlet and the outlet lass enlarging flow cross-section;

Introducing C0 ₂ and / or H ₂ 0 into the second reaction space via a second inlet adjacent the inlet end of the second reaction space to mix the carbon particles with C0 ₂ and / or H ₂ 0, wherein the mixture of carbon particles and C0 ₂ and / or H ₂ O initially has a temperature of at least 1000 ° C, preferably of at least 1400 ° C;

Reacting at least a portion of the carbon particles and the C0 ₂ to CO according to the Boudouard reaction; and or

Reacting at least a portion of the carbon particles and the H ₂ 0 to CO and H ₂ in accordance with the heterogeneous water-gas shift reaction.

14. The method of claim 13, wherein H ₂ O vapor is introduced via a third inlet downstream of the second inlet.

15. The method according to any one of claims 13 or 14, wherein the carbon particles formed during the splitting and the hydrogen are introduced together as an aerosol and at a temperature of greater than 1200 ° C, in particular greater than 1400 ° C, in the second reaction space.

16. The method according to any one of claims 13 to 14, wherein the introduction of C0 ₂

and / or H ₂ 0 via the second inlet based on the longitudinal extent of the second reaction space and starting from the first inlet in the first third, in particular in the first quarter, takes place.

17. The method according to any one of claims 13 to 16, wherein the amount of the introduced C0 _{2 is} controlled.

18. The method according to any one of claims 13 to 17, wherein the introduction of H ₂ 0 via the third inlet based on the longitudinal extent of the second reaction space and starting from the first inlet in the second half, in particular in the last third takes place.

19. The method according to any one of claims 13 to 18, wherein the second reaction space is actively heated at least in a region which lies in the longitudinal extent of the second reaction space between the second inlet and the third inlet.

20. The method according to any one of claims 13 to 19, wherein the second reaction space is heated to at least 800 ° C.

21. Method according to one of claims 13 to 20, wherein at least one of the following: the C0 ₂ and H ₂ 0 before entering the second reaction space to a

Temperature of at least 1000 ° C, preferably of at least 1400 ° C are heated.