DEVICE AND METHOD FOR THE PRODUCTION OF AN ALCOHOL SYNTHETIC GASE

Description

[0001] The invention relates to a device for producing an alcohol synthesis gas, in particular a methanol synthesis gas. Furthermore, the invention relates to a method for producing such a synthesis gas.

[0002] The production of methanol from methanol synthesis gas is known from the prior art. The methanol synthesis gas contains, in particular, hydrogen and carbon monoxide as essential components. Furthermore, various solutions for producing methanol synthesis gas are described in the prior art. It is known to obtain methanol synthesis gas from biomass or another organic substrate.

[0003] DE 10 2006 012 313 A1 describes a solution in which carbon dioxide is reduced to carbon monoxide and water to hydrogen with the removal of oxygen using an oxygen ion conductor. The disadvantage of this approach is the limited range of starting materials.

[0004] Furthermore, DE 10 2012 010 542 A1 describes a method and device for generating synthesis gas. The disadvantage here is the comparatively complex design.

[0005] The object of the invention is to provide a device and a method for the efficient, reliable and cost-effective production of an alcohol synthesis gas while overcoming the disadvantages of the prior art.

[0006] The problem is solved with respect to the device by the features listed in patent claim 1 and with respect to the method by the features listed in patent claim 6. Preferred developments arise from the respective subclaims.

[0007] The device according to the invention is based on the following: Alcohol synthesis gas is understood to be a gas mixture characterized by a precisely adjusted atomic composition, in particular in a specific numerical ratio of the carbon, hydrogen, and oxygen atoms to one another, hereinafter also referred to as the C:H:O ratio. The C:H:O ratio results from the chemical formula of the alcohol to be produced and refers to the sum of all C, all H, and all O atoms in the formula. For example, the C:H:O ratio for methanol (CH3OH or CH4O) is 1:4:1, and for ethanol (C2H5OH or C2H6O) it is 2:6:1. Since the C:H:O ratio of the organic substrate in particular can be subject to natural fluctuations that cannot always be precisely compensated, the C:H:O ratio also lies within a certain tolerance corridor. A tolerance of approximatelyA ratio of 5 percent based on the number of H atoms and O atoms is considered in accordance with the invention. For example, for an alcohol synthesis gas for methanol, a C:H:O ratio in the range of 1 to 3.8 to 4.2 to 0.95 to 1.05 is considered in accordance with the invention. The alcohol synthesis gas can always be mixed with a water vapor stream, although this superimposed water vapor stream is not included in the calculation of the C:H:O ratio. The superimposed water vapor stream is understood here to mean, in particular, water that has been synthesized alongside the alcohol after the alcohol synthesis.

[0008] The alcohol synthesis gas serves, in particular, to produce an alcohol by further reaction. The alcohol can be, in particular, methanol, hereinafter also referred to as CH3OH, but is not limited to this.

[0009] The alcohol synthesis gas is also referred to as synthesis gas in the following.

[0010] The synthesis gas may contain as components hydrogen, hereinafter also H2 and carbon monoxide, hereinafter also CO, as well as the other components in particular oxygen, hereinafter also O2, carbon dioxide, hereinafter also CO2 and water, hereinafter also H2O, as well as methane, hereinafter also CH4.

[0011] A synthesis gas intermediate is defined as a gas mixture that contains synthesis gas and, in addition, a high proportion of O2. A high proportion of O2 is defined as a numerically higher ratio of oxygen atoms to carbon or hydrogen atoms than is advantageous for alcohol synthesis and exceeds the tolerance defined above for the alcohol synthesis gas with respect to the O content. For example, for the production of methanol synthesis gas, an oxygen content is considered high if the C:H:O ratio has an O content that is more than 5 percent higher than stoichiometrically required for methanol synthesis.

[0012] The alcohol synthesis gas reactor according to the invention comprises as basic components a reactor vessel, a plasma generator and an oxygen separator.

[0013] According to the invention, the reactor vessel is designed as a bubble column reactor and has an organic substrate-water supply line, a reaction chamber, a gassing device and a withdrawal line.

[0014] By means of the organic substrate-water supply line, an organic substrate and water, preferably in the form of an organic substrate-water suspension, are introduced into the reaction chamber.

[0015] In this context, an organic substrate is understood to be a mixture of substances that can consist of a wide variety of compounds, but which essentially consist of molecules of organic chemistry. For the purposes of the present invention, "essentially consisting" means that more than 90 percent of all atoms in the organic substrate are either carbon, hydrogen, or oxygen. For example, the organic substrate can be biomass, such as that produced by shredding wood or plastic packaging. It can also be the following substances: biogenic waste, sewage sludge from sewage treatment plants, fermentation residues from a biogas plant, shredded packaging and household waste, blackwater, animal or human feces, or waste contaminated with medications or organic chemicals. The organic substrate-water supply line is also referred to below as the supply line for short.

[0016] The reaction chamber is designed to accommodate the organic substrate-water suspension, which can be introduced via the supply line or produced in the reaction chamber from the organic substrate and the water.

[0017] The gassing device is designed to supply a process gas into the reaction chamber. Preferably, the gassing device has a plurality of small outlet nozzles for supplying the process gas, at least partially in a lower region of the reaction chamber. As a result, the gassing device is designed for a dispersed distribution of the process gas.

[0018] A process gas within the meaning of the present invention is understood to be a vaporous or gaseous fluid that is deliberately added to adjust the carbon to hydrogen ratio (hereinafter also referred to as the C:H ratio) of the alcohol synthesis gas and has a different C:H ratio than the organic substrate. This can in particular also be the following substances: H2, H2O, CH4, CO2, or CO, as well as mixtures thereof.

[0019] The gassing device is thus designed to generate a bubble column in the reaction chamber by means of an arrangement of outlet nozzles. The bubble column simultaneously ensures fine distribution of the process gas in the organic substrate-water suspension, thus creating a three-phase dispersion consisting of the organic substrate as the solid phase, the water as the liquid phase, and the process gas as the gaseous phase. The bubble column ensures continuous fine distribution of all three phases. Viewed vertically, the bubble column begins at the bottom where the process gas enters via the gassing device and ends at the top at the outer surface of the three-phase dispersion.

[0020] The withdrawal line of the reactor is preferably arranged in an upper section of the reaction chamber and is designed for withdrawal of the synthesis gas or a synthesis gas intermediate product.

[0021] As a further basic component, the device according to the invention comprises the plasma generator. This is arranged in the bubble column and has anodes and cathodes, collectively referred to as the plasma electrodes. The plasma generator is designed to generate a plasma, producing the synthesis gas intermediate. The plasma generator can be arranged, in particular, at the base of the bubble column or distributed decentrally within the bubble column.

[0022] Plasma is defined as the state that a portion of the process gas or synthesis gas intermediate enters after it has been passed through an electric field and electrical power has been coupled in. The plasma itself is so energetic due to the coupled electrical power that it can dissolve (dissociate) molecular bonds in the organic-water substrate.

[0023] Furthermore, the device according to the invention comprises the oxygen separator as a further basic component. The oxygen separator is designed to separate oxygen from the synthesis gas intermediate and thus obtain the synthesis gas.

[0024] The oxygen separator can preferably be arranged in the reaction chamber, thus separating the oxygen close to its source. In this case, the synthesis gas is extracted via the extraction line. However, the solution according to the invention also encompasses an arrangement outside the reaction vessel, in which case the synthesis gas intermediate is extracted via the extraction line and fed to the oxygen separator.

[0025] The oxygen separator prevents the oxygen separated from the organic substrate by the plasma generator from forming undesirable compounds, for example with CO to form CO2 or with H2 to form H2O.

[0026] The oxygen separator can preferably be designed in particular as a ceramic separator, also as an SOEC (Solid Oxide Electrolyzer Cell) or SOFC (Solid Oxide Fuel Cell) separator.

[0027] The device according to the invention has the following advantages in particular. A technically simple and particularly trouble-free solution has been found for generating a synthesis gas by using a bubble column to create a three-phase dispersion and arranging a plasma generator within the bubble column. Surprisingly, it was discovered that plasma formation can be carried out particularly efficiently due to the large internal surface area at the boundary layers of the gaseous phase.

[0028] The gaseous portion of the plasma is entrained by the bubble column and introduced into the three-phase dispersion. In the three-phase dispersion, the composition of the gaseous phase changes along the vertical extent, with the proportion of process gas decreasing and the proportion of the synthesis gas intermediate, or depending on the design of the oxygen separator, also the synthesis gas, increasing.

[0029] The resulting synthesis gas can then be converted into an alcohol, particularly methanol, after further treatment, such as purification. Methanol (CH3OH) can be represented stoichiometrically as C + H2O + H2.

[0030] From an energetic perspective, the material energy of the methanol is provided by approximately two-thirds of the material energy of the organic substrate and approximately one-third of the electrical energy for generating the plasma.

[0031] According to an advantageous development, the device for producing an alcohol synthesis gas is characterized in that the plasma generator has a plurality of elongated and vertically arranged plasma electrodes.

[0032] The plasma electrodes are preferably rod-shaped and vertically immersed in the reaction chamber in the three-phase dispersion in the region of the bubble column. The plasma electrodes can preferably be designed as round rods and arranged in parallel. This advantageously achieves plasma formation spatially distributed over a wide area of ​​the bubble column. This simultaneously achieves a low plasma concentration and good plasma distribution. It was surprisingly found that this can suppress an undesirable rapid reaction of the oxygen component of the synthesis gas intermediate.

[0033] According to a further improvement based on this, the device for producing an alcohol synthesis gas is characterized in that the anodes and cathodes are arranged in a checkerboard manner relative to one another in a horizontal section.

[0034] A checkerboard arrangement means that anodes and cathodes alternate in both a row and a line. This ensures particularly effective plasma formation and, at the same time, its largely homogeneous distribution across the plasma electrode surface.

[0035] According to a further advantageous development, the device for producing an alcohol synthesis gas is characterized in that the oxygen separator is designed as at least one elongated and vertically arranged ceramic dip tube and is arranged in the bubble column.

[0036] According to this design, the surface of the oxygen separator is advantageously distributed longitudinally within the bubble column. This advantageously enables spatially distributed oxygen separation from the synthesis gas intermediate.

[0037] According to a next advantageous development, the device for producing an alcohol synthesis gas is characterized in that the plasma electrodes and the ceramic immersion tube are arranged substantially parallel to one another.

[0038] This refinement provides a particularly advantageous combination of spatially distributed plasma generation with spatially distributed oxygen separation. This separates the oxygen component of the synthesis gas intermediate close to its source, effectively counteracting unwanted reactions with other components of the three-phase dispersion, particularly the synthesis gas intermediate.

[0039] According to a further aspect of the invention, it relates to a process for producing such an alcohol synthesis gas.

[0040] The alcohol synthesis gas is also referred to as synthesis gas in relation to the process and contains in particular hydrogen and carbon monoxide.

[0041] The definitions and descriptions of the device for producing the alcohol synthesis gas also apply accordingly below with regard to the process for producing the alcohol synthesis gas.

[0042] The method is carried out by means of the reactor vessel, the plasma generator and the oxygen separator, these basic components being designed according to one of claims 1 to 5.

[0043] The procedure comprises the following steps: a) Providing the organic substrate and water as starting materials and feeding them into the reaction chamber via the organic substrate-water feed line, b) Providing the process gas as a further starting material and feeding it into the reaction chamber via the gassing device, c) Generating the bubble column via the gassing device to form a 3-phase dispersion of the organic substrate, the water and the process gas, d) Generating the plasma via the plasma generator in the bubble column and forming the synthesis gas intermediate, e) Separating oxygen from the synthesis gas intermediate by means of the oxygen separator and obtaining the synthesis gas.

[0044] In process step a), the organic substrate and water are prepared and introduced into the reaction chamber. Preferably, the organic substrate and water are prepared as a fine suspension and introduced into the reaction chamber, so that a process-ready suspension is present.

[0045] In addition, in process step b) the process gas is provided and introduced into the reaction chamber via the gassing device.

[0046] In process step c), according to the invention, a bubble column is generated by means of the process gas and a distribution of the process gas in the organic substrate-water suspension is generated, thus providing a finely dispersed 3-phase dispersion of the organic substrate, the water and the process gas.

[0047] According to process step d), a plasma is generated in the bubble column using the plasma generator, thus forming the synthesis gas intermediate. The chemical bonds, particularly of the organic substrate, are completely or partially broken at the plasma electrodes by applying electrical energy, thus forming the synthesis gas intermediate, which has a high oxygen content. The plasma electrodes are preferably arranged as vertical rods in the bubble column, so that the plasma is distributed over a large area in the bubble column and is rapidly carried away from the plasma electrodes by the flow of the bubble column, entering the three-phase dispersion.

[0048] After process step e), the oxygen component of the synthesis gas intermediate is finally at least partially removed by means of the oxygen separator.

[0049] The result of the process is synthesis gas, which is then available for further processing, in particular for the formation of an alcohol.

[0050] According to an advantageous development of the method, this is characterized in that in the method step e) a separation of oxygen distributed along the bubble column is carried out by means of a ceramic immersion tube which is designed to be longitudinally extended and arranged vertically in the bubble column, and the synthesis gas is withdrawn by means of the withdrawal line.

[0051] According to this refinement, the oxygen is advantageously separated close to its source, allowing it to be removed promptly and its undesirable reaction to be largely prevented. This approach can advantageously influence the composition of the synthesis gas. Since, according to this refinement, the synthesis gas intermediate is already converted into synthesis gas within the three-phase dispersion in the reaction vessel, it is removed as synthesis gas via the extraction line.

[0052] The invention is illustrated by way of example with reference to Fig. 1Schematic side view as vertical section Fig. 2Horizontal section showing the plasma electrodes Fig. 3Horizontal section with additional representation of the ceramic immersion tubes explained in more detail.

[0053] Identical reference symbols in the various figures refer to identical features or components. These reference symbols are used in the description even if they are not shown in the respective figure.

[0054] Fig. 1 shows the structure of an apparatus for producing an alcohol synthesis gas in one embodiment.

[0055] In the exemplary embodiment, the reactor vessel 10 is designed as an upright vessel of essentially cylindrical design.

[0056] The organic substrate-water supply line 11 leads laterally into the reaction chamber 12. The organic substrate-water suspension is supplied via this supply line 11 and then essentially fills the reaction chamber 12.

[0057] The outlet nozzles of the gassing device 13, through which the process gas is introduced, are located in the lower section of the reaction chamber 12. The process gas supply is schematically represented by the horizontal arrow from right to left. The supplied process gas rises in the organic substrate-water suspension in small bubbles, thus creating the bubble column 40. The fine distribution of the bubbles in the organic substrate-water suspension forms the three-phase dispersion consisting of the organic substrate as the solid phase, the water as the liquid phase, and the process gas as the gaseous phase.

[0058] Also shown is the plasma generator 20, whose plasma electrodes 21 are arranged as vertically arranged rod electrodes in the bubble column 40. The plasma electrodes thus generate the plasma in the bubble column and thus the synthesis gas intermediate, which rises in the bubbles in the bubble column 40.

[0059] The oxygen separator 30 has several ceramic immersion tubes 31, which in the exemplary embodiment are also arranged in the bubble column parallel to the plasma electrodes. The synthesis gas intermediate thus comes into contact with the ceramic immersion tubes 31 immediately after its production, where a high proportion of the oxygen is separated and discharged. The discharge of the oxygen is represented by the horizontal arrow from left to right and the designation O2.

[0060] After the oxygen has been separated, the synthesis gas continues to rise in the bubbles in the bubble column 40 and is discharged from the reaction chamber 12 via the extraction line 14. This is represented by the vertical arrow pointing upwards in the reaction chamber 12 and the horizontal arrow pointing to the right, both in bold, adjoining the end of the extraction line 14.

[0061] The synthesis gas can then be further treated, which, however, is not part of the device and method according to the invention.

[0062] Fig. 2 shows, in a horizontal section, only the arrangement of the plasma electrodes 21 in the reaction chamber 12 of the reactor vessel 10. They are arranged in the bubble column 4, with the anodes 21 and the cathodes 22 alternating in each row and each line, thus forming a checkerboard-like arrangement.

[0063] Fig. 3 shows in addition to Fig. 2 also the arrangement of the ceramic immersion tubes 31. They are each arranged in a diagonal offset in the spaces spanned by the plasma electrodes 21 and are located in an electrically neutral zone due to the arrangement of the polarities of the plasma electrodes.

[0064] For reasons of clarity, only some of the ceramic immersion tubes 31 and some of the plasma electrodes 21 have reference numerals. Reference symbols used

[0065] 10Reactor vessel 11Organic substrate-water supply line 12Reaction chamber 13Gassing device 14Sampling line 20Plasma generator 21Plasma electrodes 22Anode 23Cathode 30Oxygen separator 40Bubble column

Claims

1. A device for producing an alcohol synthesis gas, designed to produce a synthesis gas, comprising hydrogen and carbon monoxide, comprising a reactor vessel (1), a plasma generator (2) and an oxygen separator (3), wherein the reactor vessel (1) is designed as a bubble column reactor, comprising an organic-substrate-water supply line (11), a reaction chamber (12) which is designed to receive an organic-substrate-water suspension, a gassing system (13) which is designed to supply and disperse a process gas in the organic-substrate-water suspension to produce a three-phase dispersion by means of generating a bubble column (4), the dispersion comprising a solid, a liquid and a gaseous phase, the solid phase comprising the organic substrate, the liquid phase comprising the water and the gaseous phase comprising the process gas, a discharge line (14) designed to discharge the synthesis gas or a synthesis gas intermediate product, wherein the plasma generator (2) is arranged in the bubble column (4) and comprises plasma electrodes (21), wherein these are provided as anodes (22) and cathodes (23), wherein the plasma electrodes (21) are designed to generate a plasma with the production of the synthesis gas intermediate product, and wherein the oxygen separator (3) is designed to separate oxygen from the synthesis gas intermediate product to obtain the synthesis gas.

2. The device for producing an alcohol synthesis gas according to claim 1, characterized in that the plasma generator (2) comprises a plurality of longitudinally extended and vertically arranged plasma electrodes (21).

3. The device for producing an alcohol synthesis gas according to the previous claim 2, characterized in that the anodes (22) and cathodes (23) of the plasma electrodes (21) are arranged in a chessboard pattem in a horizontal section.

4. The device for producing an alcohol synthesis gas according to one of the previous claims, characterized in that the oxygen separator (3) is designed as at least one longitudinally extended and vertically arranged ceramic immersion tube (31) and is arranged in the bubble column (4).

5. The device for producing an alcohol synthesis gas according to the previous claim 4, characterized in that the plasma electrodes (21) and the ceramic immersion tube (31) are arranged substantially parallel to each another.

6. A method for producing an alcohol synthesis gas by means of the reactor vessel (1), the plasma generator (2) and the oxygen separator (3) according to one of claims 1 to 5, wherein the synthesis gas comprises hydrogen and carbon monoxide, the method comprising the following procedural steps: a) providing the organic substrate and the water as starting materials and supplying them into the reaction chamber (12) via the organic-substrate-water supply line (11), b) providing the process gas as a further starting material and supplying it into the reaction chamber (12) by means of the gassing system (13), c) generating the bubble column (4) by means of the gassing system (13) under the formation of a three-phase dispersion from the organic substrate, the water and the process gas, d) generating the plasma by means of the plasma generator (2) in the bubble column and producing the synthesis gas intermediate product, e) separating oxygen from the synthesis gas intermediate product by means of the oxygen separator (3) and obtaining the synthesis gas.

7. The method for producing an alcohol synthesis gas, characterized in that, in the process step e), a separation of oxygen in a distributed manner along the bubble column is carried out by means of a ceramic immersion tube (31), which has a longitudinally extended design and is arranged vertically in the bubble column, and the synthesis gas is discharged via the discharge line (14).