WO2017050645A1

WO2017050645A1 - Method and device for producing a synthesis gas using autothermal reforming and a membrane stage for providing oxygen-enriched air

Info

Publication number: WO2017050645A1
Application number: PCT/EP2016/071933
Authority: WO
Inventors: Joachim Johanning; Bernd Keil; Katja POSCHLAD; Julia Raab; Klaus NÖLKER
Original assignee: Thyssenkrupp Industrial Solutions Ag; Thyssenkrupp Ag
Priority date: 2015-09-22
Filing date: 2016-09-16
Publication date: 2017-03-30
Also published as: DE102015116021A1

Abstract

The invention relates to a method and a device for producing synthesis gas using autothermal reforming and a membrane stage for providing oxygen-enriched air, three partial streams being provided in connection with the membrane stage.

Description

Process and apparatus for producing synthesis gas with autothermal reforming and membrane stage for providing oxygen enriched air

The invention relates to a method and an apparatus for the production of

Synthesis gas with autothermal reforming and membrane stage to provide oxygen-enriched air.

Synthesis gas production from natural gas for large-scale production of ammonia is based today largely on the two-stage reforming process with an externally heated steam reformer as a primary reformer and operated with compressed air as an oxidant secondary reformer.

Due to its complexity and the large specific stress on essential parts, however, the steam reformer is a very expensive component and has a comparatively large proportion of the total construction costs of an ammonia synthesis plant. In principle, a steam reformer is a parallel connection of a large number of individual tube reactors whose individual capacity can not be significantly increased. The capacity of a steam reformer is therefore closely associated with a defined number of tube reactors and an increase is essentially possible only by increasing the number of tubes.

Almost all, necessary for the realization of a steam reformer components are coupled to the number of parallel-connected tubular reactors. The construction costs of a steam reformer are therefore largely proportional to the capacity of the entire system. This relationship reduces the overall degression associated with increasing capacity of the specific construction costs for ammonia synthesis plants based on the conventional process concept.

A process engineering alternative to the steam reformer with external heat is the so-called autothermal reformer (ATR). In this reformer, the heat is supplied internally by partial oxidation of the process gas to be reformed. Essentially, an ATR is a bricked combustor with a downstream catalyst bed. Accordingly, the manufacturing costs are more than an order of magnitude lower than those of a comparable steam reformer. In principle, ATR-based systems have better conditions for further increases in plant capacities. An important factor is the pressure level in synthesis gas production. Modern ammonia plants based on the steam reformer work in this area with up to 45 bara. In terms of reducing the volume flow and the concomitant reduction in the dimensions of the apparatus and piping in this area, an increase in pressure is advantageous. The higher admission pressure relieves the syngas compressor. This is of particular importance because the available synthesis gas compressors are limiting components in today's plant capacities. For further increases in plant capacities, special measures, in particular very low inlet temperatures, are generally required, which require additional technical effort. With the conventional method of two-stage reforming, however, an increase in pressure is set relatively narrow limits, because the pipes in the steam reformer already operate at the pressure limit defined by pressure and temperature.

A disadvantage of autothermal reforming is that a larger amount of oxygen must be added to the autothermal reformer. If this larger amount of oxygen is added only in the form of process air, the excess nitrogen must be removed again. It is also possible to enrich the process air with oxygen. However, this then requires the construction of an air separation plant.

In the methods usually used for the separation of air or the separation of the excess nitrogen, however, equipment is essentially used which has a pronounced cost degression with increasing capacity. System concepts based on purely autothermal reforming thus basically have the prerequisite of developing cost advantages over systems based on conventional two-stage reforming with increasing capacity.

Due to these conditions, the construction costs of ammonia synthesis plants based on the steam reforming approach those of ATR-based plants. According to the current state of knowledge, cost equalization is only expected with a plant capacity of about 4,000 tpd ammonia.

To produce a synthesis gas having the required stoichiometric ratio of hydrogen to nitrogen, an oxygen content of about 50% by volume in the oxidant of the ATR is sufficient. The high purities of oxygen that an air separation plant can provide are therefore unnecessary and cause only unnecessary equipment expense and additional costs. Frequently, a meaningful use of the resulting in the air separation nitrogen is not possible. It is therefore necessary to find other methods of oxygenation in order to economically represent the ATR technology for smaller ammonia plants.

[001 1] DE 10 2013 202 713 A1 discloses a method and apparatus for the production of low-cost, oxygen-enriched air which can be used to convert carbonaceous feedstocks such as natural gas, gasoline, heavy oil and solid carbonaceous materials such as coal into one Raw synthesis gas with a significant amount of nitrogen.

[0012] DE 696 23 536 T2 relates to the recovery of oxygen by high temperature ion transport membranes, and more particularly to the introduction of water into processes employing such membranes, thereby improving oxygen recovery and heat utilization.

However, the methods and apparatus known in the art for providing oxygen-enriched air are not entirely satisfactory and there is a need for improved methods and apparatus.

The invention has for its object to provide methods and apparatus for providing oxygen-enriched air for the production of synthesis gas in a reformer, which have advantages over the methods of the prior art.

This object is solved by the subject matter of the claims and the description.

A first aspect of the invention relates to a method for producing a synthesis gas, the method comprising the following steps:

(a) providing a gas stream comprising air;

(b) compressing the gas stream;

(c) dividing the gas stream into a first substream (Ti) and a second substream (T ₂ );

(D) passing the first partial flow (Ti) over the first side of an oxygen and / or oxygen ion permeable membrane to form a permeate stream which comprising oxygen diffused through the membrane and an oxygen-depleted retentate stream retained by the membrane;

(e) passing the second partial stream (T ₂ ) over the second side of the membrane;

(f) combining the second substream (T ₂ ) and the permeate stream to form a substream (T ₃ );

(g) introducing said partial stream (T ₃₎ in a reformer;

(h) introducing a hydrocarbonaceous composition into the reformer;

(i) reacting the substream (T ₃ ) with the hydrocarbon-containing composition to form a synthesis gas.

Synthesis gas refers to a gas mixture which is used for a synthesis, for example a gas mixture comprising hydrogen and carbon monoxide. In a preferred embodiment, the synthesis gas according to the invention is used for the synthesis of ammonia. The synthesis gas according to the invention preferably comprises nitrogen for this purpose.

In step (a) of the method according to the invention, a gas stream is preferably provided which comprises air. Preferably, the gas stream is continuous, but it can also be provided temporarily. Preferably, the gas stream comprises air, but it may also comprise further, preferably inert for the process constituents. Preferably, the oxygen content of the provided gas stream is in the range of 18 to 22% by volume.

In step (b) of the process according to the invention, the gas stream is preferably compressed. For compressing the gas stream, all methods and apparatuses known to a person skilled in the art, which are suitable for compressing a gas stream, can be used. Preferably, at least one, more preferably two or more, air compressors are used to compress the gas stream.

Preferably, the gas stream is compressed in a first air compressor so that the gas stream after compression has a pressure of at least 4 bara, more preferably at least 8 bara, at least 12 bara, at least 16 bara, at least 20 bara, at least 24 bara, at least 28 bara, at least 32 bara, at least 36 bara or at least 40 bara. The gas stream is preferably compressed in an external air compressor, preferably in four stages. Preferably, the gas stream is compressed to a pressure which is above the pressure which is usually within a reformer. In step (c) of the process according to the invention, the gas stream is preferably divided into a first partial stream (Τ-ι) and a second partial stream (T ₂ ). The splitting of the gas stream can be carried out via all methods and devices known to a person skilled in the art. Preferably, the mass ratio of first to second substream is in the range of 100: 1 to 1: 100, more preferably in the range of 80: 1 to 1:80, more preferably in the range of 60: 1 to 1:60, most preferably in the range of 40: 1 to 1:40, and more preferably in the range of 20: 1 to 1:20. In another preferred embodiment, the mass ratio of the first substream to the second substream is in the range of 1: 1 to 100: 1, more preferably in the range of 20: 1 to 100: 1, still more preferably in the range of 40: 1 to 100: 1, most preferably in the range of 60: 1 to 100: 1, and more preferably in the range of 80: 1 to 100: 1.

In a preferred embodiment, the partial flow (Τ-ι) is preferably further compressed in a further air compressor. Preferably, the first partial flow (Τ-ι) is compressed in the further air compressor so that the gas stream after compression has a pressure of at least 50 bara, more preferably at least 55 bara, at least 60 bara, at least 65 bara, at least 70 bara, at least 75th bara, at least 80 bara, at least 85 bara, at least 90 bara, at least 95 bara or at least 100 bara.

Preferably, in step (d) of the partial stream (Τ-ι) is passed over the first side of a permeable membrane for oxygen and / or oxygen ions to form a permeate stream, which comprises the oxygen diffused through the membrane, and an oxygen-depleted Retentate stream, which is retained by the membrane.

Preferably, in step (e) of the method according to the invention, the partial flow (T ₂ ) is passed over the second side of the membrane. The second side of the membrane is preferably the side of the membrane opposite the first side.

The retentate side of the membrane is accordingly the side of the membrane to which the partial flow (Τ-ι) meets and on which the oxygen-depleted retentate is formed, the permeate side corresponding to the other side of the membrane.

Membranes preferably allow the separation of mixtures, wherein driving forces for transport, for example, pressures, charges or temperatures. Suitable membranes may be porous or gas-tight. Gas-tight membranes combine high chemical inertness with good mechanical strength and can be used even at very high temperatures. By such gas-tight membranes can preferably oxygen and / or oxygen ions diffuse. Suitable gas-tight membranes are, for example, ceramics having a perovskite crystal lattice structure. As perovskite the mineral calcium titanate with the structural formula CaTi0 ₃ is called.

In the production of oxygen-conducting membranes, oxide defects are preferably incorporated into the crystal lattice in order to enable a transport of oxygen ions through the membrane. The driving force for the permeation of the oxygen or the oxygen ions through the membrane is preferably the partial pressure difference of the oxygen on both sides of the membrane. The oxygen partial pressure can be generated in various ways. For example, a pressure difference between the permeate and the retentate side of the membrane can be constructed. Furthermore, a partial pressure difference can be established by reaction of the permeated oxygen through the membrane. Furthermore, it is possible to form a partial pressure difference by purging the permeate side with an oxygen-free purging gas. The required membrane area is preferably determined by the required amount of oxygen to be separated off, the specific oxygen flow and the partial pressure difference of the oxygen.

The membrane of the invention is preferably highly selective for oxygen and / or oxygen ions permeable, but not for other gases or ions. Preferably, the permeate stream comprises at least 90% by volume of oxygen, more preferably at least 91% by volume, at least 92% by volume, at least 93% by volume, at least 94% by volume, at least 95% by volume, at least 96 Vol, -%, at least 97 vol .-%, at least 98 vol .-% or at least 99 vol .-%. The permeate stream preferably comprises at most 10% by volume of further constituents which are not oxygen or oxygen ions, more preferably not more than 9% by volume, not more than 8% by volume, not more than 7% by volume, not more than 6% by volume. %, at most 5 vol.%, at most 4 vol.%, at most 3 vol.%, at most 2 vol.% or at most 1 vol.%.

For oxygen to diffuse from the retentate side to the permeate side, a driving partial pressure difference of the oxygen must be present. In a preferred embodiment, the membrane is operated between a higher and a lower pressure level, with the higher pressure level on the side of the retentate stream, the retentate side, and the lower pressure level on the side of the permeate stream, the permeate side. Preferably, the pressure ratio of higher pressure level on the retentate side of the membrane to lower pressure level on the permeate side of the membrane is in the range of 1.8 to 2.5, more preferably in the range of 1.9 to 2.5, more preferably in the range of 2, 0 to 2.4, and most preferably in the range of 2.1 to 2.3. In a preferred embodiment, the higher pressure level is sufficiently high to match that for the Oxygen flow through the membrane to ensure necessary partial pressure difference of the oxygen. Preferably, the pressure on the retentate side of the membrane is at least 50 bara, more preferably at least 55 bara, at least 60 bara, at least 65 bara, at least 70 bara, at least 75 bara, at least 80 bara, at least 85 bara, at least 90 bara, at least 95 bara or at least 100 bara.

Preferably, the partial pressure difference of the oxygen between the retentate side and permeate side of the membrane is increased by passing the partial stream (T ₂ ) over the permeate side of the membrane. By passing the partial stream (T ₂ ) over the permeate side of the membrane, the oxygen content on the permeate side is preferably continuously diluted, as a result of which the oxygen partial pressure is lower than would be the case without the transfer of the partial stream. At the same time, however, the oxygen content of the partial stream (T ₂ ) is constantly enriched.

In step (f) of the process according to the invention, the substream (T ₂ ) and the permeate stream are combined to form a third substream (T ₃ ). The partial stream (T ₃ ) preferably has an oxygen content of at least 25% by volume, more preferably at least 30% by volume, at least 35% by volume, at least 40% by volume, at least 45% by volume or at least 50 Vol .-%.

In a preferred embodiment, the substream (T ₃ ) is used for the synthesis of ammonia. In this case, the amount of air which is necessary for introducing the nitrogen necessary for the ammonia synthesis is preferably conducted as partial stream (T ₂ ) over the permeate side of the membrane. The oxygen then permeates as permeate stream into partial stream (T ₂ ) through the membrane and enriches it to the desired oxygen content.

In step (g) of the process according to the invention, the partial stream (T ₃ ) is preferably introduced into a reformer. A reformer refers to a place where the synthesis of a synthesis gas occurs, and its structure is known to a person skilled in the art. The reformer according to the invention is preferably configured to produce hydrogen. Hydrogen is preferably produced in the reformer with the aid of steam reforming, partial oxidation or autothermal reforming. The reformer according to the invention is preferably an autothermal reformer.

In a preferred embodiment, the pressure within the reformer of the invention is in the range of 10 bara to 80 bara, more preferably in the range from 14 bara to 76 bara, in the range of 18 bara to 72 bara, in the range of 22 bara to 68 bara, in the range of 26 bara to 64 bara or in the range of 30 bara to 60 bara. Preferably, the pressure of partial flow (T ₃ ) is approximately equal to the pressure within the reformer, ie the pressure difference between the pressure of the partial flow (T ₃ ) and the pressure within the reformer is at most 2 bara, more preferably at most 1.6 bara. not more than 1, 4 bara, not more than 1, 2 bara, not more than 1, 0 bara, not more than 0,8 bara, not more than 0,6 bara, not more than 0,4 bara or not more than 0,2 bara. In another preferred embodiment, the pressure of the partial flow (T ₃ ) is greater than the pressure within the reformer. Preferably, the pressure of the partial flow T _{3 is} at least 0.2 bara greater than the pressure within the reformer, more preferably at least 0.4 bara, at least 0.6 bara, at least 0.8 bara, at least 1.0 bara, at least 1.2 bara, at least 1, 4 bara, at least 1, 6 bara, at least 1, 8 bara or at least 2.0 bara. The pressure of the partial flow (T ₃ ) is significantly determined by the higher pressure level on the retentate side of the membrane. Preferably, the higher pressure level is sufficiently high, so that the partial flow (T ₃ ) can be passed without compression in the reformer.

In step (h) of the process according to the invention, a hydrocarbon-containing composition is preferably introduced into the reformer. The hydrocarbon-containing composition preferably comprises energy sources which comprise natural gas, light gasoline, methanol, biogas or biomass. Preferably, natural gas is introduced into the reformer. Preferably, the natural gas is compressed prior to introduction into the reformer, preferably in a natural gas compressor. Preferably, the natural gas is compressed to a pressure of at least 50 bara, more preferably at least 55 bara, at least 60 bara, at least 65 bara, at least 70 bara, at least 75 bara, at least 80 bara, at least 85 bara, at least 90 bara, at least 95 bara or at least 100 bara.

Preferably, the natural gas is divided after compression in natural gas compressor in the two natural gas partial flows Ei and E ₂ . The volume ratio of E ₂ to Ei is preferably in the range of 100: 1 to 1: 1, more preferably in the range of 90: 1 to 2: 1, in the range of 80: 1 to 3: 1, in the range of 70: 1 to 4: 1, in the range of 60: 1 to 5: 1 or in the range of 50: 1 to 10: 1.

Preferably, the natural gas partial stream E _{2 is} desulphurized after compression and prior to introduction into the reformer in a reactor with the addition of hydrogen. Suitable apparatus and methods for desulfurizing natural gas are known to a person skilled in the art. After desulfurization, the sulfur content of the natural gas is at most 0.1 ppm by weight, more preferably at most 0.09 ppm by weight, at most 0.08 ppm by weight, at most 0.07% by weight. ppm, at most 0.06 ppm by weight, at most 0.05 ppm by weight, at most 0.04 ppm by weight, at most 0.03 ppm by weight, at most 0.02 ppm by weight or at most 0, 01 ppm by weight. The sulfur content comprises all compounds which contain at least one sulfur atom in their empirical formula.

Preferably, the natural gas partial stream E _{2 is divided} after compression in natural gas compressor in the two other natural gas streams E ₃ and E ₄ . The volume ratio of E ₄ to E ₃ is preferably in the range of 100: 1 to 1: 1, more preferably in the range of 90: 1 to 2: 1, in the range of 80: 1 to 3: 1, in the range of 70: 1 to 4: 1, in the range of 60: 1 to 5: 1 or in the range of 50: 1 to 10: 1.

After desulfurization, the natural gas partial stream E _{4 is} preferably mixed with medium-pressure steam. Preferably, the natural gas / vapor mixture is warmed in a tempering device, preferably at least 400 ° C, more preferably at least 450 ° C, at least 500 ° C, at least 550 ° C or at least 580 ° C. Preferably, the thus heated natural gas / vapor mixture is transferred to the reformer.

In step (i) of the process according to the invention, the substream (T ₃ ) is preferably reacted with the hydrocarbon-containing composition to form a synthesis gas.

The oxygen permeability of the membrane generally depends strongly on the operating temperature. The higher the operating temperature of the membrane, the higher the specific oxygen flux. Preferably, therefore, the gas streams which are passed over the membrane, warmed.

In a preferred embodiment, the first partial flow (Ti) is heated in a first temperature control device. Preferably, the first temperature control is a heat exchanger or a heat storage. The heat exchanger or heat accumulator according to the invention is not limited in terms of its construction according to the invention. Suitable heat exchangers include shell and tube heat exchangers, plate heat exchangers, spiral heat exchangers, U-tube heat exchangers, jacket tube heat exchangers, etc. Suitable heat accumulators basically include all components which have a comparatively large heat capacity and absorb heat from gases and can release this heat back to the gases. Suitable heat exchangers and heat accumulators are known to a person skilled in the art. Preferably, the partial stream (Τ-ι) in the first tempering to a temperature of at least 100 ° C warmed, more preferably at least 150 ° C, at least 200 ° C, at least 250 ° C, at least 300 ° C, at least 350 ° C, at least 400 ° C, at least 450 ° C, at least 500 ° C, at least 550 ° C, at least 600 ° C, at least 650 ° C, at least 700 ° C, at least 750 ° C or at least 800 ° C.

Preferably, the partial flow (Τ-ι) is supplied after leaving the temperature control of a first combustion chamber. Preferably, the partial stream (Τ-ι) by reacting with a hydrocarbon-containing composition, preferably natural gas, preferably with the desulfurized natural gas partial stream E ₃ , further heated.

Preferably, the partial stream (Τ-ι) after leaving the combustion chamber has a temperature of at least 700 ° C, more preferably at least 740 ° C, at least 780 ° C, at least 820 ° C, at least 860 ° or at least 900 ° C. Preferably, the oxygen content of the partial stream (Ti) after leaving the combustion chamber is in the range of 19 to 21% by volume, more preferably in the range of 19.2 to 20.8% by volume, in the range of 19.4 to 20.6 Vol .-% or in the range of 19.6 to 20.4 vol .-%.

In a preferred embodiment, the partial stream (T ₂ ) is warmed before flowing around the membrane in a further temperature control device. The further temperature control device is preferably a heat exchanger. In the further temperature control device, heat is preferably transferred from the partial flow (T ₃ ) to the partial flow (T ₂ ). Preferably, the second partial stream (T ₂ ) is heated in the further tempering to a temperature of at least 100 ° C, more preferably at least 150 ° C, at least 200 ° C, at least 250 ° C, at least 300 ° C, at least 350 ° C, at least 400 ° C, at least 450 ° C, at least 500 ° C, at least 550 ° C, at least 600 ° c, at least 650 ° C, at least 700 ° C, at least 750 ° C or at least 800 ° C.

In a further preferred embodiment, the partial flow (T ₂ ) is supplied to the bypass chamber before flowing around another combustion chamber. Preferably, the partial flow (T ₂ ) is warmed in the further combustion chamber by burning hydrogen. After leaving the further combustion chamber, the second partial flow (T ₂ ) preferably has a temperature of at least 700 ° C., more preferably at least 740 ° C., at least 780 ° C., at least 820 ° C., at least 860 °, at least 900 ° C., at least 940 ° C, at least 980 ° C, at least 1020 ° C, at least 1060 ° C or at least 1 100 ° C. Preferably, the oxygen content of the partial flow (T ₂ ) after leaving the further combustion chamber in the range of 14 to 21 vol .-%, more preferably in the range of 14.2 to 20.5 vol .-%, in the range from 14.4 to 20% by volume, in the range of 14.6 to 19.5% by volume, in the range of 14.8 to 19% by volume, or in the range of 15 to 18.5% by volume. %.

In the method according to the invention, only the first partial flow (Ti) or only the second partial flow (T ₂ ) or both partial flows (Τ-ι) and (T ₂ ) can be warmed. Preferably, the heating of at least one of the partial streams (Τ-ι) or (T ₂ ), the membrane is heated. In a preferred embodiment, the membrane is heated to a temperature in the range of 500 ° C to 1000 ° C, more preferably in the range of 550 ° C to 990 ° C, in the range of 600 ° C to 980 ° C, in the range of 650 ° C to 970 ° C, in the range of 700 ° C to 960 ° C or in the range of 750 ° C to 950 ° C.

Preferably, the temperature of the partial stream (T ₃ ) after leaving the membrane in the range of 500 ° C to 1000 ° C, more preferably in the range of 550 ° C to 990 ° C, in the range of 600 ° C to 980 ° C. , in the range of 650 ° C to 970 ° C, in the range of 700 ° C to 960 ° C or in the range of 750 ° C to 950 °. Preferably, the partial stream (T ₃ ) is passed after leaving the membrane via a heat exchanger, in which part of the heat is transferred to the partial stream (T ₂ ). When introduced into the reformer, the temperature of the partial stream (T ₃ ) is preferably at least 300 ° C., more preferably at least 350 ° C., at least 400 ° C., at least 450 ° C., at least 500 ° C., at least 550 ° C., at least 600 ° C. , at least 650 ° C, at least 700 ° C or at least 750 ° C. If the partial stream (T ₃ ) preheated introduced into the reformer, preferably less energy must be expended for the heating of the partial stream within the reformer, whereby hydrocarbons and oxygen can be saved.

Preferably, sufficient oxygen is still present in the retentate stream, so that it can be used as combustion air in a further combustion chamber. The retentate stream is preferably reacted with a hydrocarbon-containing composition, preferably with natural gas, preferably with the natural gas partial stream Ei, with formation of heat and offgas. After leaving the membrane, the oxygen content of the retentate stream is preferably at least 0.2% by volume, more preferably at least 0.4% by volume, at least 0.6% by volume, at least 0.8% by volume, at least 1, 0% by volume, at least 1.2% by volume, at least 1.4% by volume, at least 1.6% by volume, at least 1.8% by volume or at least 2.0% by volume , Preferably, the exhaust gas produced in the reaction has a temperature of at least 1200 ° C, more preferably at least 1300 ° C, at least 1400 ° C, at least 1500 ° C, at least 1600 ° C, at least 1700 ° C, at least 1800 ° C, at least 1900 ° C or at least 2000 ° C. In the reaction of the retentate with oxygen, heat is released and there is, inter alia, water vapor as a reaction product. The water vapor can be inside of the method according to the invention or in another method. Preferably, the heat can also be used to preheat the partial streams (Ti) and / or (T ₂ ) or other gas streams in the process according to the invention. Preferably, the pressure of the cooled exhaust gas is used in a turboexpander to at least partially cover the power requirements of the air compressor.

A second aspect of the invention relates to an apparatus for producing a synthesis gas, in particular according to a method described above, wherein the apparatus comprises the following, at least temporarily interacting components:

(A) a compression device configured to compress a gas flow comprising air;

(B) a membrane which is permeable to oxygen and / or oxygen ions, arranged after the compression device, wherein the membrane, a first and second partial stream can be fed, which are compatible in the membrane to form a third partial stream; and

(C) a reformer disposed after the membrane configured to react the third substream enriched with oxygen and a hydrocarbonaceous composition.

All preferred embodiments, which are described above in connection with the method according to the invention, apply analogously to the device according to the invention.

The components of the device according to the invention are in operative connection with each other, i. are connected to each other by suitable piping etc. in a manner which ensures the general functioning of the device. The necessary measures are known to a person skilled in the art.

A compression device is preferably configured to compress a gas stream. According to the invention, all devices suitable for compressing a gas stream can be used. Preferably, at least one, preferably a plurality of air compressors is used to compress a gas stream. For example, turbocompressors can be used as air compressors. A membrane preferably allows the separation of mixtures, wherein driving forces for transport, for example, pressures, charges or temperatures. Suitable membranes may be porous or gas-tight. The driving force for the permeation of oxygen through the membrane is the partial pressure difference of the oxygen on both sides of the membrane.

A reformer is preferably configured to react oxygen with a hydrocarbon-containing composition.

A reformer designates the location where the synthesis of a synthesis gas occurs, and its structure is known to a person skilled in the art. Preferably, the reformer is configured to produce hydrogen. Hydrogen is preferably produced in the reformer with the aid of steam reforming, partial oxidation or autothermal reforming. The reformer according to the invention is preferably an autothermal reformer.

In a preferred embodiment, the device additionally comprises the component operatively connected to the device:

(D) a combustor arranged after the membrane configured to combust a hydrocarbon-containing compound and oxygen.

Preferably, the combustion device is a device for the conversion of chemical into thermal energy, wherein preferably a gaseous hydrocarbon-containing composition is reacted with oxygen with heat release and formation of exhaust gas. The nature of such a firing device is known to a person skilled in the art. In the device according to the invention, the retentate stream is transferred after leaving the membrane into the firing device and preferably reacted with a hydrocarbon-containing composition, more preferably with natural gas.

In a preferred embodiment, the device according to the invention is used in the method according to the invention, in particular comprising an autothermal reformer.

Figures 1 and 2 illustrate schematically and by way of example the method according to the invention for the production of synthesis gas with autothermal reforming and a membrane stage, which comprises a membrane, for the provision of oxygen-enriched air, but are not to be interpreted as limiting. Figure 1 shows a simplified diagram of a plant for the production of synthesis gas with autothermal reformer. In this case, air (9) preferably in the air compressor (1) of ambient pressure is preferably compressed to 42.6 bara. Preferably, the compressed air is divided into the partial streams Ti (10) and T ₂ (12). Partial stream T ₂ (12) is preferably heated to 580 ° C. in a heat exchanger and fed to the membrane (3) as purge gas stream. Preferably, the partial flow Ti (10) is further compressed, preferably to a pressure of 102, 1 bara, and heated in a heat exchanger to 800 ° C. Preferably, in a combustion chamber (2), the compressed partial flow Ti is further heated to 906 ° C. by combustion with part of the desulfurized natural gas flow E ₃ (21). In this case, the oxygen content preferably drops slightly from 20.8% by volume to 19.9% by volume.

Preferably, only oxygen permeates through the highly selective membrane (3) into the partial flow T ₂ to form the partial flow T ₃ (14). Preferably, the partial flow Ti is thereby depleted to an oxygen content of 14% by volume, while the partial flow T ₂ (12) is preferably enriched to an oxygen content of 41.5% by volume.

The oxygen-enriched substream T ₃ (14) is preferably heated to 855 ° C. by heat transfer from the retentate stream, which is preferably heated to 900 ° C., and then passed as an oxidizer to the autothermal reformer (8).

Preferably, the oxygen-depleted retentate stream (15) still has a sufficiently high oxygen content to be used as combustion air in a second natural gas burner (4). Preferably, in this burner, the natural gas partial stream Ei (18) is burned with the retentate stream (15). Preferably, the heat of the resulting, 2000 ° C hot flue gas is used to generate steam and then relaxed in a turboexpander (5) to ambient pressure to cover the drive power of the compressor at least partially.

Preferably, natural gas (17) is compressed in a natural gas compressor (6) of 14 bara to 105 bara. Preferably, the natural gas (17) is divided into the natural gas partial flows Ei (18) and E ₂ (19). Preferably, the natural gas partial stream E ₂ (19) is desulfurized with the addition of hydrogen (20) in the reactor (7). Preferably, the natural gas partial stream E ₂ (19) is divided after desulfurization in the natural gas partial streams E ₃ (21) and E ₄ (22). Preferably, the natural gas partial stream E ₃ (21) of the desulphurised natural gas in the combustion chamber (2) is burned in order to preheat the partial flow Ti for the membrane. Preferably, the natural gas partial stream E ₄ (22) is mixed with medium-pressure steam (23) and preheated to a temperature of 580 ° C. This is preferred Natural gas / steam mixture (24) in the autothermal reformer (8) with the addition of the partial stream T ₃ (14) converted to a crude synthesis gas (25), which is rich in hydrogen and carbon monoxide.

FIG. 2 shows another variant of the method according to the invention, in which the purge air keeps the membrane at operating temperature.

Air (9) in the air compressor (1) is preferably compressed from ambient pressure to 4.6 bara. Preferably, the compressed air is divided into the partial streams Ti (10) and T ₂ (12). Preferably, the partial flow Ti (10) is further compressed to a pressure of 50 bara. Preferably, it is preheated in two heat exchangers by the hot retentate stream (16) so that it preferably enters the high pressure side of the membrane (3) at a temperature of 600 ° C. The partial stream T ₂ (12) ₃ (14) is preferably preheated in a heat exchanger by the hot partial stream T. Preferably, a small amount of hydrogen (20) is burnt in a combustion chamber with the partial flow T ₂ , so that the partial flow T _{2 is} preferably heated to 1080 ° C. Preferably, the partial flow T ₂ enters the low-pressure side of the membrane with an oxygen content of 16.5 vol .-%.

Preferably, only oxygen permeates through the highly selective membrane (3) into the heated partial flow T ₂ (13). The partial stream of Ti is preferably characterized depleted to an oxygen content of 2.3 vol .-%, whereas the partial current T ₂ .-% is enriched to an oxygen content of 37.6 vol.

Preferably, the oxygen-enriched substream T ₃ (14) heats the partial flow T ₂ (10). Preferably, the water formed in the combustion chamber is condensed out in a condenser. The partial flow T ₃ is preferably compressed in a process gas compressor (26) to the operating pressure of the autothermal reformer (8) and then passed as an oxidizer in the autothermal reformer (8).

The retentate stream (16), which is depleted of oxygen and heated by the partial stream T _2, preferably heats the partial stream Ti for the membrane (3) in two heat exchangers. Preferably, the partial flow T _{2 is} relaxed in a turboexpander (5) to ambient pressure in order to cover the power requirement of the compressor at least partially.

Preferably, natural gas (17) in a natural gas compressor (6) of 14 bara is compressed to the operating pressure of the autothermal reformer (8). The natural gas is preferably desulfurized with the addition of hydrogen (20) in the reactor (7). It is preferred then with Medium pressure steam (23) mixed and preferably preheated to a temperature of 580 ° C. Preferably, the natural gas / vapor mixture (24) is reacted in the autothermal reformer (8) with the addition of the compressed partial stream T ₃ (27) to a crude synthesis gas (25) which is rich in hydrogen and carbon monoxide.

[0073] List of Reference Numerals:

1 air compressor

2 combustion chamber

3 membrane

4 natural gas burners

5 turboexpander

6 natural gas compressor

7 reactor

8 autothermal reformers

9 air

10 first partial flow T-i

1 1 partial flow T-i, warmed

12 second partial flow T ₂

13 partial flow T ₂ , warmed

14 third partial flow T ₃

15 retentate flow

16 hot retentate stream

17 natural gas

18 natural gas partial flow Ei

19 Natural gas partial flow E ₂

20 hydrogen

21 Natural gas partial flow E ₃

22 natural gas partial flow E ₄

23 medium pressure steam

24 Natural gas / steam mixture

25 raw synthesis gas

26 process gas compressor

27 partial flow T ₃ , compressed

Claims

claims:

1 . A method of producing a synthesis gas (25), the method comprising the steps of:

(a) providing a gas stream comprising air (9);

(b) compressing the gas stream;

(c) dividing the gas stream into a first substream Ti (10) and a second substream T ₂ (12);

(d) passing the first substream Ti (10) over the first side of an oxygen and / or oxygen ion permeable membrane (3) to form a permeate stream comprising the oxygen diffused through the membrane (3) and an oxygen depleted retentate stream (15) which is retained by the membrane (3);

(e) passing the second substream T ₂ (12) over the second side of the membrane (3);

(f) combining the second substream T ₂ (12) and the permeate stream to form a third substream T ₃ (14);

(g) introducing the third substream T ₃ (14) into a reformer (8);

(h) introducing a hydrocarbonaceous composition into the reformer (8); and

(i) reacting the third substream T ₃ (14) with the hydrocarbon-containing composition to form a synthesis gas (25).

The process of claim 1, wherein the membrane (3) is operated between a higher and a lower pressure level, and wherein the higher pressure level is on the side of the retentate stream (15), the retentate side, and the lower pressure level on the side of the Permeate, the permeate, lies.

3. The process of claim 2, wherein the pressure ratio of higher pressure level on the retentate side of the membrane (3) to lower pressure level on the permeate side of the membrane is in the range of 1.8 to 2.5.

4. The method according to any one of claims 2 or 3, wherein the higher pressure level is sufficiently high to ensure the necessary for the oxygen flow through the membrane (3) partial pressure difference of the oxygen.

5. The method according to any one of claims 2 or 3, wherein the higher pressure level is sufficiently high, so that the third partial flow T ₃ (14) can be passed without compression in the reformer (8).

6. The method according to any one of the preceding claims, wherein the first partial flow T-i (10) has a pressure of at least 50 bara.

7. The method according to any one of the preceding claims, wherein the first partial flow T-i (10) is heated in a first temperature control device.

8. The method according to any one of the preceding claims, wherein the second partial flow T ₂ (12) is warmed before flowing around the membrane (3) in a further temperature control device.

9. The method according to any one of the preceding claims, wherein the third substream T ₃ (14) has an oxygen content of at least 25 vol .-%.

The process of any one of the preceding claims, wherein the membrane (3) is heated to a temperature in the range of 500 ° C to 1000 ° C.

1 1. The method according to any one of the preceding claims, wherein the retentate stream (15) is reacted with a hydrocarbon-containing composition to form heat and exhaust gas.

12. The method according to any one of the preceding claims, wherein the reformer (8) is an autothermal reformer.

13. An apparatus for producing a synthesis gas (25), in particular according to a method according to any one of the preceding claims, wherein the device comprises the following, at least temporarily interacting components:

(A) a compression device (1) configured to compress a gas flow comprising air;

(B) a membrane (3) arranged after the compression device (1), which is permeable to oxygen and / or oxygen ions, wherein the membrane first and second partial streams (10, 12) can be supplied, which are compatible in the membrane to form a third partial stream (14); and

(C) a reformer (8) arranged after the membrane (3) configured to react the third substream (14) enriched with oxygen and a hydrocarbon-containing composition.

14. The device according to claim 14, comprising the additional components operatively connected to the device:

(D) a combustor (2) arranged after the membrane (3) configured to combust a hydrocarbon-containing compound and oxygen.

15. Use of the device according to one of claims 13 or 14 in a method according to one of claims 1 to 12, wherein the device comprises an autothermal reformer.