EP3529206A1

EP3529206A1 - Method and installation for obtaining hydrogen

Info

Publication number: EP3529206A1
Application number: EP17786824.7A
Authority: EP
Inventors: Volker Göke; Christian Voss
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2016-10-18
Filing date: 2017-10-04
Publication date: 2019-08-28
Also published as: RU2019110119A; KR20190073443A; CN109843791B; KR102438581B1; RU2739072C2; RU2019110119A3; US20190247781A1; ZA201902184B; WO2018072865A1; CN109843791A; DE102016012391A1; US11298648B2; BR112019006827A2

Abstract

The invention relates to a method for obtaining hydrogen (b) from crude gas (a) originating from a coke oven (110), in which method the crude gas (a) generated in the coke oven (110) is condensed, and then pressure swing adsorption is used to separate impurities from the crude gas (a). Prior to the pressure swing adsorption process, oxygen is removed from the crude gas (a) using non-thermal plasma. The invention also relates to an installation for obtaining hydrogen from crude gas.

Description

description

Process and plant for the production of hydrogen

The invention relates to a method and a plant for the production of hydrogen from raw gas, which is produced in a coke oven, according to the preambles of the independent claims.

State of the art

There may be coking plants at steel mills' sites where coke, which is needed for steelmaking, is produced. In this case, coke is recovered in so-called coke ovens from, for example, hard coal. Several coke ovens can be provided in particular in the form of a so-called coke oven battery, that is, a plurality of coke ovens juxtaposed. As a further product falls next to the coke so-called coke oven gas or crude gas. This crude gas may, for example, about 60 to 65% hydrogen, about 20 to 25% methane and lower levels of, inter alia, nitrogen, carbon monoxide, carbon dioxide, oxygen and heavy hydrocarbons. The exact composition usually varies depending on the operation of the coke oven and the coal used.

From the raw gas, the hydrogen can now be obtained in a very pure form. For this purpose, the raw gas can first be compressed and then one

Pressure swing adsorption be supplied. By means of pressure swing adsorption, it is possible to remove or separate impurities from the raw gas and to provide a high-purity stream of hydrogen. If here and in the following of hydrogen, which is obtained from raw gas, is mentioned, it should be understood in particular also a gas mixture with a high proportion of hydrogen, in particular at least 90, 95 or 99 mol%.

The extraction of hydrogen from raw gas from a coke oven by means of

Pressure swing adsorption is known per se and, for example, in Yang and Lee: Adsorption dynamics of a layered bed PSA for H2 recovery from coke oven gas, AIChE Journal, Volume 44, Issue 6, June 1998, pages 1325-1334 or Takeuchi et. al .:

Hydrogen separation from COG (Coke Oven Gas) by PSA, Journal of the Fuel Society of Japan 62 (12), pages 989-994, December 1983. However, it can be problematic with such methods that leaks can occur in the coke ovens, which are generally operated under reduced pressure. Such leaks may increase with increasing age of coke ovens. By leaks ambient air and thus oxygen can get into the coke oven and thus into the raw gas. The higher the proportion of oxygen in the raw gas, the higher the risk that, together with the hydrogen or other gases within the pressure swing adsorption plant at certain process steps and / or in the residual gas pressure swing adsorption an ignitable mixture. There is the possibility of converting the oxygen by means of catalysts, for example by reacting oxygen with hydrogen to form water or steam, so that the purity of the hydrogen is further increased. Such catalysts are known, for example, by the term "deoxo." However, since many impurities are present in the crude gas, such catalysts would be damaged quickly or have a long service life increased, however, the ignitable mixture can not be avoided or reduced, and in particular additionally receives a moist product gas, which usually has to be post-dried.

The object of the present invention is to provide an improved and in particular safer way of obtaining hydrogen from raw gas produced in a coke oven. Disclosure of the invention

This task is accomplished by a method and a plant for the extraction of

Hydrogen solved with the features of the independent claims.

Embodiments are the subject of the dependent claims and the following description. Advantages of the invention

The present invention is based on a known per se or plant for the recovery of hydrogen from raw gas, which is produced in a coke oven, as described in more detail below. The raw gas that is produced in the coke oven is first compressed and then impurities are separated by pressure swing adsorption. According to the invention, before the pressure swing adsorption using a non-thermal plasma oxygen is depleted from the raw gas. By non-thermal plasma is meant a plasma which is not in thermal equilibrium, i. that the electrons in the plasma have a much higher energy or temperature than the other components, which often only at

Room temperature or slightly above, for example, to about 325 K. The

Temperature of the electrons may be, for example, about 10 ⁵ K or higher.

In contrast, there is also thermal plasma, ie plasma, which is in the

thermal equilibrium stands and in which the electrons and the rest

Ingredients have approximately the same energy or temperature, which is usually very high, for example, between some 1000 K and 10 ⁶ K or higher.

The non-thermal plasma can be generated in particular by means of dielectric barrier discharge (Dielectric Barrier Discharge or DBD, also known as silent electrical discharge) or by means of microwaves. In the former, a dielectric material or a dielectric layer may be provided between two electrodes and an alternating electric field may be applied to the electrodes. The microwaves, however, can be generated, for example, in a Magetron and passed into a reaction space.

Using the non-thermal plasma, the oxygen in the raw gas can react with other proportions in the raw gas and thus be removed from the raw gas or depleted. This can be an emergence of an ignitable mixture of oxygen and hydrogen and / or other combustible gases in

Pressure swing adsorber or be reduced in the resulting there residual gas. ever according to the type of plant can thus a depletion to less than 200 ppm

Oxygen content (based on the amount of substance, i.e. 0.02 mol%) may be possible, while a feed gas mixture usually from a proportion of 0.6 mol% to ignitable mixtures in the pressure swing adsorption (at least in

Process steps) or in the residual gas pressure swing adsorption - at least temporarily - is flammable. Thus, coke oven gases or raw gases can be made available for efficient hydrogen production even with an oxygen content of more than 0.6 mol%.

It is also particularly advantageous that in this way older systems for

Recovery of hydrogen from raw gas can be retrofitted from a coke oven. Coke ovens can have a maximum service life of 30 to 70 years, which usually means that leaks and thus the proportion of oxygen in the raw gas increase.

Preferably, oxygen is depleted from the raw gas by activating catalytic oxygen removal using the thermal plasma. In particular, catalysts with platinum and / or palladium and / or copper and / or zinc, in particular aluminum or aluminum oxide, can be used for such a catalytic oxygen removal. The catalyst can be in a

Plasma field of the thermal plasma or with respect to a stream of the raw gas to the plasma field. In this case, the catalyst may also be designed such that, in particular, higher hydrocarbons are separated or reacted from the crude gas. In particular, nickel-containing materials are suitable for this purpose. Also conceivable is a combination of several,

in particular different catalysts or materials.

By generating non-thermal plasma are not high

Process temperatures required so that when using a catalyst - in contrast to a conventional application - no or at least only a very small extent coking of the catalyst occurs. The catalysts mentioned at the outset (so-called DeOxo) can thus also be used before the pressure swing absorber. Overall, the delivery of oxygen can be made even more effective and efficient. In particular, it is expected that through the Activation by non-thermal plasma a lower doping of the

Catalyst is possible, resulting in a cost savings.

Advantageously, the crude gas before the pressure swing adsorption and after the raw gas is compressed, pretreated. This can be carried out in particular adsorptively or catalytically and / or regenerated or non-regenerated and / or using a pressure swing adsorption membrane hybrid process. In the case of using the pressure swing adsorption membrane hybrid method for this purpose, for example, a suitable membrane may be provided in front of the pressure swing adsorber, to enable a certain separation of the impurities before adsorption. The oxygen can be depleted using the non-thermal plasma from the raw gas before or after the raw gas is pretreated before pressure swing adsorption. The separation of impurities is improved by such pretreatment prior to pressure swing adsorption.

Oxygen can be depleted of the raw gas using the non-thermal plasma after the raw gas is compressed. If no

Pretreatment takes place, the generation of non-thermal plasma can thus between the compression (or a corresponding compressor) and the

Pressure swing adsorption (or a corresponding pressure swing adsorber) take place. If a pretreatment takes place, then the generation of the nonthermal plasma can take place between the compression and the pretreatment or between the pretreatment and the pressure swing adsorption. Depending on the situation, one or the other variant can be more efficient.

It is particularly preferred, however, if oxygen is depleted of the raw gas using the non-thermal plasma before the raw gas is compressed. The generation of the non-thermal plasma thus takes place before the compression (or before a corresponding compressor). This is the earliest possible point in the process flow where depletion can occur.

This is advantageous, in particular, if hydrocarbons were oxidized, so that fouling of the compressor is reduced.

A plant according to the invention for the production of hydrogen from crude gas comprises a coke oven, in which the raw gas can be generated, a compressor, the raw gas can be supplied from the coke oven and which is adapted to compress the raw gas, and a pressure swing adsorber to which the raw gas can be supplied after exiting the compressor and which is adapted to separate impurities from the raw gas and provide hydrogen. Furthermore, one is now

Plasma generator provided which is arranged in front of the pressure swing adsorber and adapted to generate non-thermal plasma in the raw gas.

With regard to further advantageous embodiments of a system according to the invention and the advantages thereof, reference is made to the above statements to avoid repetition, which apply accordingly.

The invention will be explained in more detail with reference to the accompanying drawing showing various parts of the system, by means of which the

inventive measures are explained.

Short description of the drawing

FIG. 1 shows a plant not according to the invention for the production of hydrogen in the form of a schematic process flow diagram.

FIG. 2 shows a preferred embodiment of a plant according to the invention in the form of a schematic process flow diagram.

FIG. 3 shows a further preferred embodiment of a system according to the invention in the form of a schematic process flow diagram.

FIG. 4 shows a further preferred embodiment of a system according to the invention in the form of a schematic process flow diagram. FIG. 5 shows a further preferred embodiment of a system according to the invention in the form of a schematic process flow diagram.

Detailed description of the drawing 1 shows a plant 100 for the recovery of hydrogen (H ₂ ) from crude gas is shown schematically, based on which first the underlying method for the production of hydrogen to be explained, on which the invention is based. In a coke oven 110, which may also be a so-called coke oven battery, in addition to coke, coke oven gas or raw gas is also generated, which via a pipeline 115 as stream a a compressor 120, which may be, for example, a compressor , is supplied. This crude gas may, for example, about 60 to 65% hydrogen, about 20 to 25% methane and lower levels of, inter alia, nitrogen, carbon monoxide, carbon dioxide, oxygen and heavy hydrocarbons. The exact composition may vary depending on the operation of the coke oven and the coal used.

While the raw gas from the coke oven 110 is usually provided with a slight negative pressure, the pressure swing adsorber requires a pressure of, for example, between 5 and 10 bar, possibly even higher, which is generated by the compressor. After the raw gas has been compressed in the compressor 120, i. After the pressure has been increased, the raw gas is supplied to the pressure swing adsorber 140. In the pressure swing adsorber 140 impurities are now separated by pressure swing adsorption of the raw gas. By impurities are meant in particular those components in the raw gas (which is a gas mixture) which are undesirable, i. present all shares except hydrogen. It is understood that not all of the pressure swing adsorption

Impurities can be completely removed or separated. Typical values for the purity of the hydrogen that can be provided by the pressure swing adsorber 140 as stream b are, for example, at least 98 mol% and higher.

The separated gas in the pressure swing adsorber 140 or the separated portions (residual gas) are supplied as stream d of the pipeline 1 15, so that it can then be used downstream, for example, as a heating gas.

For a more detailed description of the method presented here and

In particular, the pressure swing adsorption is at this point in specialist literature, as it was initially mentioned, for example, referenced. In the raw gas (stream a), as mentioned, an oxygen content of 0.6 mol% or higher may be present, which may in particular also come about through leaks in the coke oven 110 and the ambient air sucked thereby.

In the figures 2 to 5, various preferred embodiments of a system according to the invention are now shown schematically, by means of which the present invention will be explained in more detail. For the most part, in particular with regard to the basic components and the corresponding method steps, the systems shown in FIGS. 2 to 5 correspond to the system 100 according to FIG. 1. In this respect, reference should also be made to the description there, wherein identical components are designated by the same reference numerals.

FIG. 2 shows a plant 200 in which a plasma generator 150 and a catalytic converter 151 between the pipeline 1 15 and the compressor 120 are provided in comparison to the plant 100 according to FIG.

The plasma generator 150 can be, for example, a device with two electrodes to which an alternating voltage can be applied, between which a dielectric material is introduced. In this way, a non-thermal plasma can be generated in the raw gas (stream a).

The catalyst 151 may be, for example, a palladium, platinum, copper or zinc catalyst on an aluminum surface. Also conceivable are a combination of several of these materials or a plurality of catalysts each having one of these materials.

In this case, the catalytic converter 151 may be arranged in a plasma field that arises during the production of the non-thermal plasma. Thus, in the case of the dielectric barrier discharge, the catalyst 151 may be disposed, for example, between the dielectric material and a corresponding electrode.

However, it is also conceivable that the catalytic converter 151 is arranged downstream of the plasma generator 150 with respect to the current a and its current direction. By generating the non-thermal plasma, the kataiytische oxygen removal or the removal of oxygen from the raw gas can then be carried out particularly efficiently and in particular at relatively low temperatures. In the subsequent compression and in the pressure swing adsorber 140 so that the raw gas is already depleted of oxygen, so that no more ignitable mixture is present and a safe separation of other impurities is possible.

Typical values for the purity of the hydrogen, here now from

Pressure swing adsorber 140 can be provided as stream b lie

for example, at least 99 mol% and higher, in particular also 99.9999 mol% are conceivable.

FIG. 3 shows a plant 300 in which a pretreatment device 130 is provided between the compressor 120 and the pressure swing adsorber 140 in comparison to the plant 200 according to FIG.

The pretreatment device 130 can have, for example, a membrane in which a separation of impurities is possible even before the pressure swing adsorption. Together with the pressure swing adsorber 140 thus with the membrane a two-stage pressure swing adsorption membrane hybrid process for

Separation of impurities provided.

FIG. 4 shows a plant 400 in which, compared to the plant 300 according to FIG. 3, the plasma generator 150 and the catalyst 151 are now provided between the compressor 120 and the pretreatment device 130 instead of between the pipeline 115 and the compressor 120.

FIG. 5 shows a plant 500 in which, compared to the plant 400 according to FIG. 4, the plasma generator 150 and the catalytic converter 151 instead of between the compressor 120 and the pretreatment device 130 now between the plasma generator 150

Pre-treatment device 130 and the pressure swing adsorber 140 are provided.

The variants shown in FIGS. 4 and 5 can be more efficient, depending on the existing system or the possibilities with respect to the variant of FIG

Allow separation of oxygen. It is understood that other variants are conceivable. For example, the plasma generator 150 and the catalyst 151 in a system without

Pre-treatment device, as shown for example in Figure 2, be provided between the compressor and the pressure swing adsorber.

Claims

claims

1. A process for the recovery of hydrogen (b) from crude gas (a) from a

Coke oven (110), in which the raw gas (a) which is produced in the coke oven (110) is first compressed and in which impurities are separated from the raw gas (a) by means of pressure swing adsorption,

characterized in that before the pressure swing adsorption using non-thermal plasma oxygen is depleted from the raw gas (a).

2. The method of claim 1, wherein oxygen is depleted from the raw gas (a) by activating catalytic oxygen removal using the thermal plasma.

3. The method of claim 2, wherein for the catalytic oxygen removal

Platinum and / or palladium and / or copper and / or zinc, in particular on

Aluminum or alumina.

4. The method of claim 2 or 3, wherein for the catalytic oxygen removal at least one catalyst (151) is used, which in a

Plasma field of the thermal plasma or with respect to a stream of

Raw gas (a) is arranged after the plasma field.

5. The method according to any one of the preceding claims, wherein the non-thermal plasma is generated by dielectric barrier discharge or by means of microwaves.

6. The method according to any one of the preceding claims, wherein the raw gas (a) before the pressure swing adsorption and after the raw gas (a) is compressed, is pretreated, in particular adsorptively or catalytically and / or regenerated or non-regenerated and / or using a

Pressure swing adsorption membrane hybrid process.

7. The method according to claim 6, wherein oxygen by means of the non-thermal

Plasmas from the raw gas (a) is depleted before or after the raw gas (a) is pretreated before the pressure swing adsorption.

8. The method according to any one of the preceding claims, wherein oxygen is depleted by means of the non-thermal plasma from the raw gas (a) after the raw gas (a) is compressed.

9. The method according to any one of claims 1 to 6, wherein oxygen is depleted by means of the non-thermal plasma from the raw gas (a) before the raw gas

(a) is compressed.

10. Plant (200, 300, 400, 500) for recovering hydrogen (b) from raw gas (a), with a coke oven (110) in which the raw gas (a) is produced, a compressor (1 0), the the raw gas (a) from the coke oven (110) can be supplied and which is adapted to compress the raw gas (a), and a pressure swing adsorber (140) to which the raw gas (a) after discharge from the compressor (120) can be fed and which is adapted to separate impurities from the raw gas (a) and to provide hydrogen (b),

characterized by a plasma generator (150) positioned in front of

Pressure swing adsorber (140) arranged and adapted to generate non-thermal plasma in the raw gas (a).

The plant (200, 300, 400, 500) according to claim 10, further comprising at least one catalyst (151) for removing oxygen from the raw gas (a), which in one

Plasma field of the non-thermal plasma generated by the plasma generator (150) or with respect to a stream of the raw gas (a) after the plasma field is arranged.

12. Plant (300, 400, 500) according to claim 10 or 11, further comprising a

Pre-treatment device (130) through which the raw gas (a) is feasible before it is fed to the pressure swing absorber (140).