Method and apparatus for generating gas products using a

Shift converter

The invention relates to a method for producing a hydrogen-containing

Gas product in a first or a second modification having a lower hydrogen content than the first, wherein a water vapor, carbon monoxide and hydrogen containing and with a water vapor / carbon monoxide ratio (D / CO ratio) between 1.8 and 2.5 mol / mol synthesis gas provided is treated with the aid of a shift converter in order to obtain an intermediate product from which water and acid gases are separated off in order to obtain the hydrogen-containing gas product.

The invention also relates to a device for performing the

method according to the invention.

Methods and devices of the generic type are used in particular to generate hydrogen in petroleum refineries, which is generally required in large quantities, for example for the operation of desulphurizers and hydrocrackers. For this purpose, heavy refinery residues are usually converted together with an oxidizing agent as well as water vapor and possibly carbon dioxide in a gasifier by partial oxidation to a mixture of substances rich in hydrogen and carbon monoxide, which also contains carbon dioxide, water vapor and solids, which are mainly soot particles that caused by incomplete conversion of the carbon contained in the inserts. The mixture of substances known as synthesis raw gas, which leaves the gasifier at a temperature that is typically between 1300 and 1450 ° C,

To increase the hydrogen yield, the synthesis gas is fed into a shift converter, where carbon monoxide is catalytically active in an exothermic shift reaction with water according to the equation

CO + H 2 0 <-► H 2 + C0 2

is converted to hydrogen and carbon dioxide.

At the same time, trace components present in the synthesis gas and undesired in the gas product, such as metal carbonyls, carbon oxide sulfide (COS) and hydrocyanic acid (HCN), are removed by the catalyst used in the shift converter

retained or converted to substances that can be removed with little effort from the intermediate product obtained in the shift converter.

The shift converter is usually operated with a D / CO ratio between 1.8 and 2.5, and thus a significant excess of water, which is necessary for a

Shifting the reaction equilibrium to the hydrogen side ensures and also brings about a lessening of the thermal load on the catalyst and the suppression of undesired side reactions. The synthesis gas usually has a corresponding D / CO ratio when it emerges from the water scrubbing, so that it is not necessary to adjust its water content upstream of the shift converter.

The intermediate product that leaves the shift converter at a temperature of approx. 450 ° C is referred to below as an intermediate product cooler

Cooling device supplied in order to condense out water and to obtain a largely anhydrous gas mixture with a temperature of approx. 40 ° C for forwarding to an acid gas scrubber. In the acid gas scrubbing, which is about a methanol scrubbing, the gas mixture is converted in particular by the

Separation of carbon dioxide and sulfur components a gas product consisting predominantly of hydrogen, referred to as raw hydrogen, is obtained, which is optionally subjected to a fine purification in order to obtain hydrogen with the for its

Purpose required to produce purity

The intermediate product cooler normally comprises three heat exchanger groups that are connected in series to form a cooling chain. At the outlet of each heat exchanger group there is a condensate separator from the one in the previous one

The two-phase mixture of substances produced by cooling, in particular condensed water, is separated off and a gas phase is transferred to the next one

Heat exchanger group or the acid gas scrubbing generated. In the first

Heat exchanger group are, for example, to be heated or to

Evaporating boiler feed water and / or process condensate or steam to be superheated are used as cooling media, while cooling air and cooling water can be used in addition to these substances in the subsequent, second heat exchanger group. In the third and last group of heat exchangers, air and water coolers are used to keep the gas phase at a suitable temperature for introduction into the acid gas scrubbing system.

If one or more hydrogen consumers in the refinery fail, for example due to maintenance work, the hydrogen requirement temporarily drops and the hydrogen production must be adjusted accordingly. However, the obvious possibility of operating the hydrogen production plant at partial load for this purpose does not apply, since a constant decrease in the heavy refinery residues used for the production of synthesis gas, which are permanently incurred and otherwise not usable, must be guaranteed at all times. The synthesis gas is therefore generated with a constant amount regardless of the reduced hydrogen requirement, but further treated differently, so that instead of the raw hydrogen, a gas product is obtained which, in addition to hydrogen, also has a greater proportion of carbon monoxide,

In order to be able to use the gas product in a turbine, it should be

The carbon monoxide content is above and its hydrogen content is below 35% by volume, otherwise the maximum permissible flame temperature would be exceeded. According to the prior art, only part of the synthesis gas is therefore passed into the shift converter, while the remainder is bypassed to the shift converter and then combined with the converted partial flow to form the intermediate product. In this case, however, a minimum amount of the carbon monoxide present in the synthesis gas is always converted to hydrogen, since a shift converter is only functional to a limited extent or can even be damaged if it is operated with less than 25% of its nominal load. Another disadvantage of this type of process management is that the part of the bypass led to the shift converter

Trace components present in synthesis gas and undesired in the gas product are not retained or converted on the shift catalyst and therefore have to be removed at high cost upstream of the acid gas scrubber in a purification stage that is not used in normal operation.

The object of the present invention is therefore to provide a method and a device of the generic type which are suitable for overcoming the described disadvantages of the prior art.

In terms of the method, the object is achieved according to the invention in that the synthesis gas is fed to the shift converter in the form provided in order to obtain the gas product in the first modification, while the ratio of water vapor to carbon monoxide in the synthesis gas is achieved through the separation of water upstream of the shift -Converter is set to a value between 0.1 and 0.6 mol / mol in order to obtain the gas product in the second modification.

The invention makes use of the fact that the water-gas shift reaction does not take place or takes place only to a very limited extent at a D / CO ratio of the synthesis gas of less than 1.0 and the carbon monoxide contained in the synthesis gas therefore does not increase or only to a small extent Hydrogen is converted. The intermediate product is therefore obtained with an H 2 / CO ratio that largely corresponds to that of the

Syngas corresponds. The low D / CO ratio does not affect the ability of the shift catalyst to produce undesirable gas products

Retain or convert trace components so that the intermediate product withdrawn from the shift converter is largely free of such substances.

If the gas product is generated in the first modification, a preferred embodiment of the method according to the invention provides that the intermediate product, which leaves the shift converter at a temperature of typically approx. 270 ° C., is passed through an intermediate product cooler for cooling and removing water, which has at least three connected in series to form a cold chain

Includes heat exchanger groups. At the end of each heat exchanger group, the condensate that forms during cooling is separated from the gas phase before the gas phase is passed on to the following heat exchanger group for further cooling or to an acid gas separator to remove acid gases.

The intermediate product preferably enters the first heat exchanger group at the temperature at which it leaves the shift converter, while a largely anhydrous gas phase exits the last heat exchanger group at a temperature that allows the gas phase to be treated in the acid gas separation device. The intermediate product for cooling and removing water is particularly preferred by means of exactly three heat exchanger groups

Intermediate product cooler passed.

It is sensible to also cool the synthesis gas provided for the separation of water and the adjustment of the D / CO ratio to the value required for the generation of the gas product in the second modification in order to condense out water vapor to the required extent. The condensate produced when the synthesis gas is cooled is separated off in order to obtain the synthesis gas with a reduced water content for forwarding to the shift converter and a water-rich liquid phase.

The synthesis gas provided is very particularly preferably passed through one or more of the heat exchanger groups of the intermediate product cooler in order to separate off water and set the D / CO ratio. Since the temperature of the synthesis gas is significantly lower than the temperature obtained in the first modification in the shift converter when the gas product was generated

Intermediate product, the synthesis gas is usefully converted into a

Heat exchanger group initiated downstream of the first

Heat exchanger group of the intermediate product cooler is arranged. After the water that has condensed out has been separated off, the water content is reduced

Synthesis gas is drawn off from the intermediate product cooler via a removal point located upstream of the last heat exchanger group and introduced into the shift converter. In this operating mode, all of the heat exchanger groups through which synthesis gas flows are blocked for the intermediate product, but the remaining heat exchanger groups can be used to cool it.

Due to the low D / CO ratio of the synthesis gas with reduced water content, a comparatively small amount of heat is released in the shift converter, so that the intermediate product leaves the shift converter at a temperature that is only slightly higher than the temperature at which the synthesis gas with reduced water content into or out of the shift converter

Intermediate product cooler exits. Appropriately, therefore, when the gas product is obtained in the second modification, the intermediate product becomes his

Cooling downstream of the extraction point for the synthesis gas with reduced water content, but introduced into the intermediate product cooler upstream of the last heat exchanger group.

The invention also relates to a device for generating a

hydrogen-containing gas product in a first or a lower one

Hydrogen content as the first, second modification, with a shift converter and a feed device, via which a synthesis gas containing water vapor, carbon monoxide and hydrogen and provided with a water vapor / carbon monoxide ratio between 1.8 and 2.5 mol / mol is supplied to the shift converter can be fed to obtain an intermediate product, as well as a separation device with which the gas product can be obtained from the intermediate product by separating water and acid gases.

In terms of the device, the object is achieved according to the invention in that the feed device comprises a first and a second flow path having a gas dryer as well as a switching device with which the

Synthesis gas can be passed either via the first or the second flow path, with the synthesis gas passing through the shift converter via the first

Flow path can be supplied in the form provided in order to obtain the gas product in the first modification, while the synthesis gas for obtaining the gas product in the second modification is passed via the second flow path to the shift converter, the ratio of water vapor to carbon monoxide in the gas dryer in the Synthesis gas can be adjusted to a value between 0.1 and 0.6 mol / mol by separating off water.

The separation device preferably comprises an intermediate product cooler in which the intermediate product obtainable in the first modification in the shift converter during the production of the gas product can be cooled and dried. Particularly preferably, the intermediate product cooler has at least three heat exchanger groups connected in series to form a cooling chain, at the respective end of which a separator is arranged, with which a two-phase that occurs during cooling

Mixture of substances can be separated into a gas and a liquid phase. A

The separator is either with a further heat exchanger group of the intermediate product cooler or with one belonging to the separation device

Sour gas separation device connected, so that the gas phase obtained in the separator either for further cooling and drying in the further

Heat exchanger group or for removing acid gases in the

Sour gas separation device can be passed on.

The gas dryer expediently comprises a cooling device as well as a separator, with which condensate formed during the cooling of the synthesis gas in the cooling device can be separated from the gas phase. The gas dryer is particularly preferably at least one of the

Heat exchanger groups of the intermediate product cooler. In this version of the device according to the invention, the intermediate product cooler can be used simultaneously for drying the synthesis gas and for cooling and drying the intermediate product available in the shift converter, a heat transfer group used as a gas dryer being blocked for the treatment of the intermediate product. It makes sense to use one that can be replaced as a gas dryer

Heat exchanger group arranged downstream of the first heat exchanger group of the intermediate product cooler.

If the intermediate product cooler is designed with exactly three heat exchanger groups, the invention provides that the second heat exchanger group can be used as a gas dryer, while the third heat exchanger group located downstream of the second can be used to cool and dry the intermediate product obtained in the second modification when the gas product is obtained .

In the following, the invention is to be explained in more detail on the basis of an exemplary embodiment shown schematically in FIG.

FIG. 1 shows a preferred variant of the invention. Material flows, lines and valves which arise or are flowed through during the production of the gas product in the first modification are shown with solid lines, while those only during the production of the gas product in the second modification

Accruing material flows or lines and valves flowing through are shown with dashed lines or with black filling.

A synthesis gas containing hydrogen, carbon monoxide and water is provided via line 1 at a temperature of approx. 240 ° C. and a D / CO ratio between 1.8 and 2.5 mol / mol. In order to produce a gas product 7 in a first modification consisting largely of hydrogen and free of carbon monoxide, this is done, for example, by gasifying heavy

Synthesis gas 1 obtained from refinery residues via line 2 and the shut-off element a is introduced directly into the shift converter S, where the carbon monoxide contained in synthesis gas 1 is reacted with water in a catalytically supported exothermic shift reaction to form hydrogen and carbon dioxide. Substances also contained in synthesis gas 1 but undesired in the gas product, such as metal carbonyls,

Carbon oxide sulfide and hydrocyanic acid are retained or decomposed on the catalyst, so that such substances are practically non-existent downstream of the shift converter S. The intermediate product 3, consisting largely of water, carbon dioxide and hydrogen, which exits the shift converter S at a temperature of approx. 270 ° C. due to the heat released during the shift reaction is fed via the shut-off device b to the separating device A, in which it first the

Intermediate product cooler Z flows through.

The intermediate product cooler Z comprises three heat exchanger groups Z1, Z2 and Z3, which are connected in series to form a cooling chain in which the intermediate product 3 is gradually cooled down to approx. 40 ° C. and thereby dried. At the outlet of each heat exchanger group, water contained in intermediate product 3 and condensed during the previous cooling is separated off in a condensate separator (not shown), so that a dried gas phase is obtained in each case. While the first dried gas phase 4 from the first

Heat exchanger group Z1 and the second dried gas phase 5 via the shut-off element c from the second heat exchanger group Z2 to each other

Drying are continued in the next heat exchanger group, the third dried gas phase 6 from the third heat exchanger group Z3 is present with a temperature and a water content that allows its forwarding to the

Allow the acid gas scrubber R belonging to the separation device A. The intermediate product 3 is in the first heat exchanger group Z1, for example, against what is to be heated

Boiler feed water and / or process condensate is cooled down to approx. 200 ° C and in the subsequent, second heat exchanger group Z2, for example when generating low-pressure steam and heating demineralized water, it is cooled down to approx. 150 ° C. In the third and last heat exchanger group Z3, air and water coolers can be used in order to obtain the dried gas phase 6 largely anhydrous and at a temperature of approx. 40 ° C.

In the acid gas scrubber R, which is, for example, a methanol scrubber, carbon dioxide and other acid gases are separated from the third dried gas phase 6, the gas product 7 being obtained in the first modification as raw hydrogen. From the raw hydrogen 7 can in one

Pressure swing adsorber (not shown) pure hydrogen for delivery to a consumer are generated.

In order to produce a gas product 14 in a second modification with a lower hydrogen content than the first, the valves shown with white filling are closed and the valves shown with black filling are opened, which opens up a new flow path to the shift reactor for the synthesis gas 1 S results. Via line 10 and the shut-off device d, synthesis gas 1 is bypassed to the shift converter S which acts as a synthesis gas dryer

Heat exchanger group Z2 of the intermediate product cooler Z supplied in order to adjust the D / CO ratio in the synthesis gas by condensing out water. The dried synthesis gas 11 leaves the heat exchanger group Z2 with a D / CO ratio between 0.1 and 0.6 mol / mol and a temperature of approx. 185 ° C. in order to be fed to the shift converter S via the valve e. Because of the low steam content of the dried synthesis gas 11, the exothermic shift reaction does not take place, or only to a very limited extent, and that contained in the synthesis gas

Carbon monoxide is not converted into hydrogen, or only to a very small extent. The intermediate product 12 is therefore obtained with an H / CO ratio which largely corresponds to that of the synthesis gas 1. The low D / CO ratio of the dried synthesis gas 11 does not affect the ability of the catalyst used in the shift converter S to be undesirable in the gas product 14

Retain or convert trace components so that the

Intermediate product 12 is largely free of such substances.

Since no or only a very small amount of heat is released due to the shift reaction in the shift converter S which does not take place or takes place only to a very limited extent, the intermediate product 12 can be introduced into the third heat exchanger group Z3 for cooling and drying via the valve f, from which a largely anhydrous gas phase 13 consisting of carbon dioxide, carbon monoxide and hydrogen is withdrawn and fed to the acid gas scrubber R. In the

Sour gas scrubbing R are separated from the gas phase 13, carbon dioxide and other sour gases, the gas product 14 being obtained in the second modification, which essentially consists of the carbon monoxide and hydrogen contained in the synthesis gas 1 and is used, for example, as fuel in a gas turbine (not shown) can.

Claims

1. A method for generating a hydrogen-containing gas product in a first (7) or a, a lower hydrogen content than the first having second modification (14), wherein a water vapor, carbon monoxide and

Synthesis gas (1) containing hydrogen and provided with a water vapor / carbon monoxide ratio (D / CO ratio) between 1.8 and 2.5 mol / mol is treated with the aid of a shift converter (S) to convert an intermediate product (3, 12) to be obtained, from each of which water and acid gases to obtain the hydrogen-containing gas product (7, 14) are separated, thereby

characterized in that the synthesis gas (2) is fed to the shift converter (S) in the form provided in order to obtain the gas product in the first modification (7), while the ratio of water vapor to carbon monoxide in the synthesis gas (11) is achieved by the separation of water upstream of the shift converter (S) is set to a value between 0.1 and 0.6 mol / mol in order to obtain the gas product in the second modification (14).

2. The method according to claim 1, characterized in that in the production of the gas product in the first modification (7) obtained intermediate product (3) for cooling and the removal of water is passed through an intermediate product cooler (Z), the at least three in series to one Interconnected cold chain

Includes heat exchanger groups (Z1, Z2, Z3).

3. The method according to any one of claims 1 or 2, characterized in that the synthesis gas (1) provided for separating off water and setting the D / CO ratio to the value required for generating the gas product in the second modification (14) is cooled in order to condense water vapor to the required extent.

4. The method according to claim 2, characterized in that the synthesis gas (1) provided for the separation of water and the adjustment of the D / CO ratio to that for the production of the gas product in the second

Modification (14) required by one or more of the value

Heat exchanger groups of the intermediate product cooler is passed.

5. Apparatus for generating a hydrogen-containing gas product in a first (7) or a second modification (14) having a lower hydrogen content than the first, with a shift converter (S) and a

Feed device via which a synthesis gas containing water vapor, carbon monoxide and hydrogen and provided with a water vapor / carbon monoxide ratio between 1.8 and 2.5 mol / mol can be fed to the shift converter to obtain an intermediate product (3, 12), as well as a

Separation device (A) with which the gas product (7, 14) can be obtained from the intermediate product (3, 12) by separating water and acid gases, characterized in that the feed device has a first (2) and a gas dryer (Z2) comprising the second flow path (10, Z2, 1 1) and a switching device with which the synthesis gas (1) can be passed either via the first or the second flow path, the synthesis gas (1) passing the shift converter via the first flow path (2) in the form provided can be fed to the gas product in the first

To obtain modification (7), while the synthesis gas (1) to obtain the gas product in the second modification (14) via the second flow path (10, Z2, 1 1) to the shift converter (S), wherein in the gas dryer ( Z2) the ratio of water vapor to carbon monoxide in the synthesis gas

Water separation can be adjusted to a value between 0.1 and 0.6 mol / mol.

6. The device according to claim 5, characterized in that the

Separation device (A) comprises an intermediate product cooler (Z) which has at least three heat exchanger groups (Z1, Z2, Z3) connected in series to form a cooling chain, at the respective end of which a separator is arranged, with which a two-phase mixture of substances produced during cooling is converted into a gas - and a liquid phase can be separated.

7. Device according to one of claims 5 or 6, characterized in that the gas dryer (Z2) comprises a cooling device and a separator with which when the synthesis gas (1) is cooled in the cooling device

condensate formed can be separated from the gas phase (1 1).

8. The device according to claim 6, characterized in that the gas dryer is at least one of the heat exchanger groups (Z2) of the

Intermediate product cooler (Z) acts.