Method and device for producing syngas

Abstract

Methods and devices are provided for producing syngas with an adjustable molar CO/H.sub.2 ratio. Syngas can have different proportions of CO and H.sub.2 (molar CO/H.sub.2 ratio) depending on the type and composition of starting materials. To set the desired molar CO/H.sub.2 ratio, a first sub-process is combined with at least one additional sub-process selected from: a sub-process T.sub.2 by which a second syngas B is generated from the starting material, the syngas having a molar ratio (V.sub.2) of CO to H.sub.2, wherein V.sub.1V.sub.2; a sub-process T.sub.3 by which the hydrocarbon(s) of the hydrocarbon-containing starting material is/are split substantially into solid carbon and hydrogen; and a sub-process T.sub.4 based on the reaction equation: CO+H.sub.2O.fwdarw.2CO.sub.2+H.sub.2. The methods and devices are suitable for producing syngas useful as a starting material in a plurality of chemical syntheses, for example oxo, Fischer-Tropsch, or Reppe syntheses.

Claims

1. A method for producing a synthesis gas product having a desired, adjustable molar CO/H.sub.2 ratio denoted by V from a hydrocarbon-containing starting material selected from the group consisting of pyrolysis gas, pyrolysis oil, flare gas, biogas and natural gas, the method comprising steps of: performing a first sub-process T.sub.1 by which a first synthesis gas A is generated from a first sub-stream of the hydrocarbon-containing starting material by feeding the first sub-stream of the hydrocarbon-containing starting material directly into a first plasma reactor , the first synthesis gas A having a molar ratio of CO to H.sub.2 which is denoted by V.sub.1, the first sub-stream of the hydrocarbon-containing starting material and the hydrocarbon-containing starting material having the same composition; performing at least one additional sub-process selected from the group consisting of a second sub-process T.sub.2 and a third sub-process T.sub.3, wherein the second sub-process T.sub.2 comprises generating a second synthesis gas B from a second sub-stream of the hydrocarbon-containing starting material by feeding the second sub-stream of the hydrocarbon-containing starting material directly into a second plasma reactor, the second synthesis gas B having a molar ratio of CO to H.sub.2 denoted by V.sub.2, wherein V.sub.1 V.sub.2, the first and second sub-streams of the hydrocarbon-containing starting material having the same composition, and wherein the third sub-process T.sub.3 comprises breaking down hydrocarbon(s) of a third sub-stream of the hydrocarbon-containing starting material into solid carbon and hydrogen by feeding the third sub-stream of the hydrocarbon-containing starting material directly into a third plasma reactor, the first and third sub-streams of the hydrocarbon-containing starting material having the same composition; and combining the first synthesis gas A generated in the first sub-process T.sub.1 with at least one of the second synthesis gas B generated in the second sub-process T.sub.2 and the hydrogen produced in the third sub-process T.sub.3 to obtain the synthesis gas product having the desired molar CO/H.sub.2 ratio V by adjusting a mixing ratio of the combined gases.

2. The method according to claim 1, wherein V.sub.1 is less than V.sub.2, optionally V.sub.1 <1 and V.sub.2 1.

3. The method according to claim 1, wherein at least one of the first and second sub-processes (T.sub.1, T.sub.2) generates a low-hydrogen synthesis gas whose molar ratio of CO to H.sub.2 is at least 1, and wherein at least one other of the first and second sub-processes (T.sub.2, T.sub.1) generates a high-hydrogen synthesis gas whose molar ratio of CO to H.sub.2 is less than 1.

4. The method according to claim 3, wherein the at least one other of the first and second sub-processes (T.sub.1, T.sub.2) for producing a high-hydrogen synthesis gas is based on a following reaction equation:
C.sub.nH.sub.2n+2+n.H.sub.2O.fwdarw.n.CO+(2n+1).H.sub.2, (I) wherein C.sub.nH.sub.2n+2represents alkane, and n is 1 to 20; and wherein the reaction is optionally:
CH.sub.4+H.sub.2O.fwdarw.CO+3H.sub.2(Ia).

5. The method according to claim 1, wherein at least one of the first and second sub-processes (T.sub.1, T.sub.2) generates a low-hydrogen synthesis gas based on a following reaction equation:
C.sub.nH.sub.2n+2+.sub.n.CO2.fwdarw.2.sub.n.CO+(n+1).H.sub.2, (II) wherein C.sub.nH.sub.2n+2represents alkane, and n is 1 to 20; and wherein the reaction is optionally:
CH.sub.4+CO.sub.2.fwdarw.2CO+2H.sub.2(IIa).

6. The method according to claim 1, wherein the first sub-process (T.sub.1) generates the first synthesis gas A based on a following reaction equation:
C.sub.nH.sub.2n+2+n.CO.sub.2.fwdarw.2n.CO+(n+1).H.sub.2, (II) wherein C.sub.nH.sub.2n+2represents alkane, and n is 1 to 20, wherein the first synthesis gas A is a low-hydrogen synthesis gas, and wherein the reaction is optionally:
CH.sub.4+CO.sub.2.fwdarw.2 CO+2 H.sub.2; (IIa) wherein the second sub-process (T.sub.2) produces the second synthesis gas B according to a following reaction equation:
C.sub.nH.sub.2n+2n.H.sub.2O .fwdarw.n.CO+(2n+1).H.sub.2, tm (I) wherein C.sub.nH.sub.2n+2represents alkane, and n is 1 to 20, wherein the second synthesis gas is a high-hydrogen synthesis gas, and wherein the reaction is optionally:
CH.sub.4 +H.sub.2O .fwdarw.CO+3 H.sub.2;(Ia) and wherein the first and second synthesis gases A B are combined, during which the mixing ratio is adjusted such that the synthesis gas product having the desired molar CO/H.sub.2 ratio V is obtained.

7. The method according to claim 6, wherein the mixing ratio of the first and second synthesis gases A and B is adjusted by one of the first and second sub-processes being run at a higher or lower throughput than the respective other sub-process.

8. The method according to claim 7, wherein the second sub-process which produces the high-hydrogen synthesis gas run at a higher throughput than the first sub-process at 1.5 times to 10 times the throughput relative to the first sub-process.

9. The method according to claim 1, wherein the molar ratio of CO to H.sub.2 (V.sub.1, V.sub.2, . . . ) present in the synthesis gases (A, B, . . . ) produced by the sub-processes is determined continuously, and the sub-processes are controlled by open-loop or closed-loop control as a function of a determined ratio such that a synthesis gas product having the desired CO/H.sub.2 ratio V is obtained.

10. The method according to claim 1, wherein the third sub-processes (T.sub.3) causes pyrolytic decomposition of hydrocarbons according to a following reaction equation:
C.sub.nH.sub.2n+2.fwdarw.n.C.sub.solid+(2n+2).H.sub.2;(IV) wherein the reaction is optionally:
CH.sub.4 .fwdarw.C.sub.solid+2 H.sub.2(IVa).

11. The method according to claim 10, wherein the pyrolytic decomposition of hydrocarbons is combined with a sub-process for producing a low-hydrogen synthesis gas and/or with a sub-process for producing a high-hydrogen synthesis gas, and wherein the hydrogen produced by the pyrolytic decomposition is combined with the synthesis gas of one of the first and second sub-processes (T.sub.1, T.sub.2) to increase the proportion of hydrogen contained in the synthesis gas.

12. The method according to claim 11, wherein the sub-process for producing a high-hydrogen synthesis gas is based on a following reaction equation:
C.sub.nH.sub.2n+2+n.H.sub.2O.fwdarw.n.CO+(2n+1).H.sub.2,(I) wherein C.sub.nH.sub.2n+2represents alkane, and n is 1 to 20; and wherein the reaction is optionally:
CH.sub.4+H.sub.2O.fwdarw.CO +3 H.sub.2(Ia).

13. The method according to claim 11, wherein the sub-process for generating a low-hydrogen synthesis gas is based on a following reaction equation:
C.sub.nH.sub.2n+2+n.CO.sub.2 .fwdarw.2n.CO+(n+1).H.sub.2,(II) wherein C.sub.nH.sub.2n+2represents alkane, and n is 1 to 20; and wherein the reaction is optionally:
CH.sub.4+CO.sub.2.fwdarw.2CO+2 H.sub.2(IIa).

14. The method according to claim 1, further comprising a downstream sub-process T.sub.4 based on a water-gas shift reaction (III) which causes an increase in the H.sub.2 content present in the synthesis gas product:
CO +H.sub.2O.fwdarw.2CO.sub.2+H.sub.2(III).

15. The method according to claim 1, wherein at least two of the sub-processes for synthesis gas production based on following reaction equations (I) and (II) are carried out in a combined manner in a same plasma reactor:
C.sub.nH.sub.2n+2+n.H.sub.2O.fwdarw.n.CO+(2n+1).H.sub.2,(I)
C.sub.nH.sub.2n+2+n.CO.sub.2.fwdarw.2n.CO+(n+1).H.sub.2(II)

16. The method according to claim 15, wherein a proportion of admixed CO.sub.2 and/or a proportion of admixed H.sub.2O is varied as a function of the composition of the hydrocarbon-containing starting material, optionally a hydrocarbon-containing feed gas, in order to obtain a synthesis gas product having a constant CO/H.sub.2 ratio.

17. The method according to claim 15, wherein the hydrocarbon-containing starting material (C.sub.nH.sub.2n+2) is a biogas mixed with CO.sub.2 and/or H.sub.2O and is converted to the desired synthesis gas product, optionally in a microwave plasma reactor.

18. The method according to claim 1, wherein a hydrocarbon-containing starting material having a CO.sub.2 content is used as a starting material, and wherein the starting material is converted in a first sub-process according to a reaction formula:
C.sub.nH.sub.2n+2+n.CO.sub.2.fwdarw.2n.CO+(n+1).H.sub.2 (II) to a synthesis gas which is converted in a second sub-process, with addition of water, to a synthesis gas higher in hydrogen, wherein the two sub-processes are carried out in a combined manner in a same plasma reactor, optionally in a microwave plasma reactor.

19. The method according to claim 1, wherein a hydrocarbon-containing gas which, relative to the hydrocarbon content, contains CO.sub.2 in excess is used as a starting material, the gas optionally being a pyrolysis gas or a flare gas, wherein this feed gas is enriched with hydrocarbons or with a hydrocarbon-containing mixture, optionally natural gas, prior to use as a starting material or during the conversion to synthesis gas.

20. The method according to claim 19, wherein the starting material enriched with hydrocarbons is converted under action of a plasma, optionally a microwave plasma, to synthesis gas, with addition of water to increase the hydrogen content of the synthesis gas.

21. The method according to claim 1, wherein a hydrocarbon which is liquid under normal conditions or a mixture of hydrocarbons which is liquid under normal conditions, optionally oils from a pyrolysis, is used as the hydrocarbon-containing starting material.

22. The method according to claim 1, wherein the synthesis gas product(s) is/are used in at least one subsequent synthesis process as a starting material(s), and wherein a residual proportion of unreacted synthesis gas accumulating in the subsequent synthesis process is admixed to the hydrocarbon-containing starting material and thereby recycled back into the method.

23. A method for the production of synthesis gas from a hydrocarbon-containing starting material according to claim 1, wherein the hydrocarbon-containing starting material, in a gaseous form, is enriched with hydrocarbons prior to or during its use for synthesis gas production, the gaseous hydrocarbons or a hydrocarbon-containing gas being selected from the group comprising methane, ethane, propane, butane and natural gas.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

(2) FIG. 1 is a schematic flow diagram showing the principle of a method according to one embodiment of the invention;

(3) FIG. 2 is a schematic flow diagram showing the principle of a further embodiment of the method and device according to the invention;

(4) FIG. 3 is a schematic flow diagram showing the principle of another embodiment and device according to the invention as a concrete example for the embodiment shown in FIG. 1;

(5) FIG. 4 is a schematic flow diagram showing the principle of another embodiment of the method and device according to the invention, based on FIG. 2 and FIG. 3;

(6) FIG. 5 is a schematic flow diagram showing the principle of another embodiment of the method and device according to the invention, in a modification of the embodiment shown in FIG. 1;

(7) FIG. 6 is a schematic flow diagram showing the principle of another embodiment of the method and device according to the present invention, in a modification of the embodiment shown in FIG. 3; and

(8) FIG. 7 is a schematic flow diagram showing a variant of the embodiment shown in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

(9) FIG. 1 shows the principle of a method according to the invention in which a hydrocarbon-containing starting material (E) is divided into two sub-streams. In two different sub-processes (T.sub.1, T.sub.2), which are combined with each other and which are carried out in two reactors (R.sub.1, R.sub.2), the starting material is converted into synthesis gases (A, B) having a molar CO/H.sub.2 ratio V.sub.1 or V.sub.2, respectively, (V.sub.1<V.sub.2 or V.sub.1>V.sub.2). The reactors (R.sub.1, R.sub.2) are preferably plasma reactors, particularly microwave plasma reactors.

(10) In particular, such methods are suitable as sub-processes (T.sub.1, T.sub.2) as are based on the above-mentioned reaction equations (I), (Ia), (II) and (IIa).

(11) The synthesis gas streams thus obtained are combined in an adjustable or automatically controllable mixing device (M), so that a synthesis gas product (P) with a molar CO/H.sub.2 ratio (V) results.

(12) To measure the CO and H.sub.2 contents and to determine the CO/H.sub.2 ratios in the synthesis gas streams of the sub-processes (T.sub.1, T.sub.2) and in the synthesis gas product (P), gas sensors (G.sub.1, G.sub.2, G.sub.3) are installed which have corresponding measuring devices and evaluation units. By open-loop or closed-loop control devices associated therewith, the throughput in the reactors (R.sub.1, R.sub.2) and/or the mixing ratio in the mixing device (M) are/is controlled by open-loop or closed-loop control such that a synthesis gas product (P) having a desired, preferably a constant, CO/H.sub.2 ratio (V) results.

(13) FIG. 2 shows the principle of a further embodiment of the method and device according to the invention, in whichin a modification of the embodiment shown in FIG. 1a combination with a third sub-process T.sub.3 provided. This sub-process can, for example, be a process based on the above-mentioned reaction equation (IV) or (IVa) (plasma-pyrolytic decomposition with formation of solid carbon and H.sub.2). As shown in FIG. 1, gas sensors with associated measuring devices, evaluation units, control devices, etc. may be provided (not shown in FIG. 2).

(14) FIG. 3 shows the principle of another embodiment and device according to the invention, whereinas a concrete example for the embodiment shown in FIG. 1as the sub-process T.sub.1, a method is used which is based on the reaction equation (steam reforming)
CH.sub.4+H.sub.2O.fwdarw.CO+3H.sub.2(Ia)
and wherein as the sub-process T.sub.2, a method is used which is based on the reaction equation (dry reforming)
CH.sub.4+CO.sub.2.fwdarw.2CO+2H.sub.2(IIa)

(15) In the above case, methane or a methane-containing gas mixture (e.g. natural gas, biogas) is used as hydrocarbon-containing starting material.

(16) The reactants required for these reactions (H.sub.2O, CO.sub.2) are, where necessary, fed, via corresponding supply lines, into the respective reactor (R.sub.1, R.sub.2).

(17) As shown in FIG. 1, gas sensors may be provided which comprise associated measuring devices, evaluation units, open-loop or closed-loop control devices, etc. (not shown in FIG. 3). One can also make use of the possibility of controlling, by open-loop or closed-loop control, the admixture of H.sub.2O and/or CO.sub.2 as a function of the values determined for the CO/H.sub.2 ratio.

(18) FIG. 4 shows the principle of another embodiment of the method and device according to the invention, based on FIG. 2 and FIG. 3, as described above. A method for the pyrolytic decomposition of hydrocarbons according to the following reaction equation
CH.sub.4.fwdarw.C.sub.solid+2H.sub.2(IVa)
is used as the sub-process T.sub.3.

(19) FIG. 5 shows the principle of another embodiment of the method and device according to the invention, in a modification of the embodiment shown in FIG. 1, as described above. Here, an additional reactor R.sub.4 is provided which is arranged downstream of the two reactors R.sub.1, R.sub.2. In that reactor, the synthesis gas generated by mixing (M) the synthesis gas streams (A, B), formed in the sub-processes (T.sub.1, T.sub.2) and reactors (R.sub.1, R.sub.2), respectively, is subjected to a further sub-process (T.sub.4), which comprises a water-gas shift reaction (reaction equation (III)). The CO.sub.2 from the sub-process (T.sub.4) can optionally be returned to the sub-process (T.sub.2) as feed gas (line (rf) in FIG. 5).

(20) FIG. 6 shows the principle of another embodiment of the method and device according to the present invention, in a modification of the embodiment shown in FIG. 3, as described above. The synthesis gas product (CO, H.sub.2), produced by mixing (M) of the two synthesis gas sub-streams, is used in a further reactor (MR) for the (catalytic) synthesis of methanol and dimethyl ether. Unreacted synthesis gas and CO.sub.2 accumulating in the synthesis are recycled back, as residual gas (CO, H.sub.2, CO.sub.2, H.sub.2O, C.sub.xH.sub.y (hydrocarbons)), to the beginning of the process chain for the production of synthesis gas and are used as feed gas or mixed into the feed gas. In this way, an almost 100% conversion of materials can be achieved.

(21) FIG. 7 shows a variant of the embodiment shown in FIG. 6, wherein the synthesis gas product (CO, H.sub.2), produced by mixing (M) the two synthesis gas sub-streams, is converted in a Fischer-Tropsch synthesis, in at least one further reactor (FT), into products such as liquid and gaseous hydrocarbons, alcohols, etc. The accumulating residual gas (may contain CO, H.sub.2, CO.sub.2, H.sub.2O, C.sub.xH.sub.y) is recycled back into the process and re-used as the feed gas, or mixed into the feed gas, as described in FIG. 6.

(22) The above-described embodiments, illustrated with reference to the drawings, represent only a few examples of embodiments and of applications of the present invention. Each of these exemplary embodiments can, either individually or in various combinations, form the subject matter of one or more claims. Furthermore, each of these embodiments can be combined with one or more feature(s) from the foregoing description of the invention.

(23) It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.