WO2025186011A1 - Energy-efficient method for crude hydrogen regeneration - Google Patents

Abstract

The present invention relates to a method for regenerating crude hydrogen, which contains at least carbon monoxide, hydrogen, methane and carbon dioxide, using an absorbent. The method is characterized in that energy from the unloaded absorbent is made useful in the process by means of a heat transfer medium in order to save energy costs and CO2.

Description

Energy-efficient process for raw hydrogen processing

The invention relates to a process for processing raw hydrogen containing at least carbon monoxide, hydrogen, methane, and carbon dioxide using an absorbent. The process is characterized in that energy from the discharged absorbent is harnessed within the process by means of a heat transfer medium, thereby saving energy costs and CO2 emissions.

The processing of raw hydrogen by separating carbon dioxide can be achieved in various ways. The most common methods include the use of absorption media, such as water, physical absorption media such as Selexol, or chemical absorption media such as Sulfinol. Sulfinol can be used to remove acidic components such as carbon dioxide from natural gas, long-distance gas, and synthesis gas. The acidic components are scrubbed from the raw gas under pressure using an absorption media composed of sulfolane and diisopropanolamine in an absorption column. In a subsequent process step, the acidic gas components are expelled from the loaded absorption media.

Particularly when removing gas components from the loaded absorption medium in a desorption column, a large amount of energy must be supplied externally. Heating steam is typically used as an external heat source. Rising energy prices therefore have a significant impact on the process. Furthermore, large amounts of CO2 are released during the generation of heating steam.

The objective of the present invention was to provide a purification process for raw hydrogen that requires less or no external energy input. In addition, a purification process that can reduce CO2 emissions should be provided.

The underlying objects could be achieved by the inventive process for processing crude hydrogen according to claim 1. Preferred embodiments of the process are specified in the subclaims.

The process according to the invention is a process for processing raw hydrogen which contains more than 50 vol.% hydrogen, less than 10 vol.% carbon monoxide, methane and more than 10 vol.% carbon dioxide, wherein the vol.% refers in each case to the total volume of the raw synthesis gas and wherein the process comprises at least the following steps: a) bringing the raw hydrogen into contact with an absorption medium which consists of 10 to 20 wt.% water, 40 to 50 wt.% DIPA and 35 to 45 wt.% sulfolane, wherein the amounts of the three components water, diisopropylamine (DIPA) and sulfolane add up to 100%, in at least one absorption column, as a result of which at least part of the carbon dioxide passes into the absorption medium and a loaded absorption medium BA is formed and as a result of which a processed hydrogen stream is obtained which contains at least 75 vol.% hydrogen; b) feeding the loaded absorption medium BA to at least one desorption column, wherein the loaded absorption medium BA is preheated before entering the desorption column; c) heating the loaded absorption medium in the desorption column by means of a bottom evaporator SV, which is fed with a stream taken from the lower end of the desorption column and, after passing through the bottom evaporator SV, is returned to the desorption column, whereby at least part of the carbon dioxide is outgassed from the loaded absorption medium and a discharged absorption medium EA is formed; d) returning the discharged absorption medium EA to the at least one absorption column in step a), whereby energy is transferred from EA to a liquid or gaseous heat transfer medium W, whereby a heat transfer medium W1 is formed and whereby the discharged absorption medium EA is cooled before entering the at least one absorption column; e) compressing at least a portion of the heat transfer medium W1 to produce a compressed heat transfer medium W2 having a higher pressure than the heat transfer medium W1; and f) transferring energy from the compressed heat transfer medium W2 to the stream in the bottom evaporator SV.

The process according to the invention is characterized by heat integration, in which energy is transferred in the form of heat from one part of the process to another. A heat transfer medium is used for this purpose. The absorption process is exothermic, with the absorption heat generally being extracted from the system via a cooler. The process according to the invention, however, utilizes this heat by using a heat transfer medium. The absorption heat is not dissipated via the cooling water, but is used to evaporate a heat transfer medium and then used to heat the bottom evaporator.

The raw hydrogen used for processing can come from various sources. One possibility is that the raw hydrogen is a sulfur-free, necessary excess synthesis gas from a hydroformylation plant. The raw hydrogen can also be taken as exhaust gas from a steam reformer to adjust the CO content. The raw hydrogen is preferably sulfur-free, i.e. it contains no sulfur-containing compounds. According to the invention, the raw hydrogen contains more than 50 vol.% hydrogen, preferably more than 55 vol.% hydrogen, particularly preferably more than 59 vol.% hydrogen, in each case based on the total volume of the raw hydrogen. The amounts of carbon dioxide in the raw hydrogen can vary and are a maximum of 45 vol.%, preferably a maximum of 40 vol.%, particularly preferably a maximum of 35 vol.%, in each case based on the total volume of the raw hydrogen. In addition, the raw synthesis gas contains less than 10 vol.% carbon monoxide, preferably less than 7 vol.% carbon monoxide, in each case based on the total volume of the raw synthesis gas. The raw synthesis gas also contains more than 10 vol.% Carbon dioxide, preferably more than 20 vol.% carbon dioxide, in each case based on the total volume of the raw synthesis gas.

In the first step a), the raw hydrogen is brought into contact in at least one absorption column with an absorption medium which consists of 10 to 20 wt.% water, 40 to 50 wt.% DI PA and 35 to 45 wt.% sulfolane, the amounts of the three components water, diisopropylamine (DIPA) and sulfolane adding up to 100%, whereby at least part of the carbon dioxide passes into the absorption medium and a loaded absorption medium BA is formed and whereby a purified raw hydrogen gas stream is produced.

The absorbent comprises at least water, diisopropylamine (DIPA), and sulfolane. In the present invention, the absorbent used consists only of the three components water, diisopropylamine (DIPA), and sulfolane. This absorbent can contain the three components in varying amounts. The absorbent consists of 10 to 20 wt.% water, 40 to 50 wt.% DIPA, and 35 to 45 wt.% sulfolane, each based on the total absorbent. The amounts of the three components water, diisopropylamine (DIPA), and sulfolane must add up to 100%.

The absorption in step a) of the process according to the invention is carried out in at least one absorption column. However, it is also possible to use more than one absorption column in step a). According to the invention, the absorption in step a) is preferably carried out in at least two absorption columns, preferably in exactly two absorption columns.

If the absorption in step a) is carried out in two absorption columns, the discharged absorption medium EA is first passed to the second absorption column, where a partially loaded absorption medium is formed. This is then passed to the first absorption column, where the loaded absorption medium is formed, which is then passed for desorption in step c). The raw hydrogen is then preferably first introduced into the first absorption column and from there passed to the second absorption column. The purified raw hydrogen gas is thus removed at the top of the second absorption column.

Any absorption column known to the person skilled in the art can be used as the absorption column. The absorption column preferably contains internals. Suitable internals are, for example, trays, unstructured packings (random packings) or structured packings. Trays which are typically used are bubble-cap trays, sieve trays, valve trays with fixed or movable valves, tunnel trays or slotted trays. Unstructured packings are generally random packings. The packings which are typically used are Raschig rings, Pall rings, Berl saddles, SuperRings/SuperRings Plus or Intalox® saddles. Structured packings are marketed, for example, under the trade name Mellapak® by Sulzer. In addition to the internals mentioned, other suitable internals are known to the person skilled in the art and can also be used. In a particularly preferred embodiment of the present invention, the Absorption column a plurality of internals, preferably 2 to 50 internals, particularly preferably 2 to 15 internals.

The absorption in step a) of the process according to the invention is preferably operated at a pressure of 10 to 40 bar, particularly preferably at a pressure of 14 to 30 bar. The temperature during the absorption in step a) is preferably in the range of 30 to 80 °C, more preferably in the range of 35 to 70 °C. If the absorption in step a) is carried out in two absorption columns, the pressure and temperature in the two absorption columns are each within the above-mentioned ranges (pressure: 10 to 40 bar, preferably 14 to 30 bar / temperature 30 to 80 °C, preferably 35 to 70 °C), but do not have to be identical. This means that the absorption columns can also be operated at different pressures and temperatures.

It is further preferred that the absorption in step a) is operated in countercurrent, i.e. the crude hydrogen and the absorbent are brought into contact with one another in countercurrent. If two or more absorption columns are present, it is preferred if all absorption columns are operated in countercurrent. It is preferred if the crude hydrogen is introduced into the lower part of the at least one absorption column and the absorbent is introduced into the upper part of the at least one absorption column. The crude hydrogen will then flow upwards and come into contact with the absorbent flowing down. At least the carbon dioxide is at least partially scrubbed out in the process. Better distribution and thus improved contact between crude hydrogen and absorbent can be achieved via the internals preferably present in the at least one absorption column.

In step a), a purified hydrogen stream is produced which contains at least 75 vol.% hydrogen, preferably at least 80 vol.% hydrogen, particularly preferably at least 85 vol.% hydrogen, in each case based on the total volume of the purified hydrogen stream. The purified raw hydrogen stream can then be used as a raw material.

In step b) of the process according to the invention, the loaded absorbent BA is fed to at least one desorption column, preferably only a single desorption column, wherein the loaded absorbent BA is preheated before entering the desorption column. After absorption, the loaded absorbent BA has a temperature in the range of 30 to 80 °C, preferably 35 to 70 °C. However, desorption takes place at a higher temperature than absorption. In this respect, it is advantageous to preheat the loaded absorbent BA before entering the desorption column, since not all of the desorption energy needs to be introduced via the bottom evaporator of the desorption column.

The preheating of the loaded absorption medium BA is preferably carried out by transferring energy from the discharged absorption medium EA to the loaded absorption medium BA in a heat exchanger. This involves a direct transfer of energy from the discharged absorption medium EA to the loaded absorption medium BA. Direct transfer means that the two streams Although they do not contact each other directly, energy, especially heat, is transferred from EA to BA without the presence of an additional heat transfer medium.

The preheating in step b) can be carried out using heat exchangers known to those skilled in the art. Suitable evaporators that can be used as heat exchangers include, for example, natural circulation evaporators, forced circulation evaporators, forced circulation evaporators with expansion, boiler evaporators, falling-film evaporators, or thin-film evaporators. In addition to the aforementioned evaporators, any other evaporator design known to those skilled in the art that is suitable for the desired preheating can also be used.

The separation of at least the carbon dioxide from the laden absorption medium takes place in at least one desorption column. Any desorption column known to the person skilled in the art can be used as the desorption column. The desorption column preferably contains internals. Suitable internals include, for example, trays, unstructured packings (random packing), or structured packings. Trays typically used are bubble-cap trays, sieve trays, valve trays with fixed or movable valves, tunnel trays, or slotted trays. Unstructured packings are generally random packings. Raschig rings, Pall rings, Berl saddles, SuperRings/SuperRings Plus, or Intalox® saddles are typically used as packings. Structured packings are marketed, for example, under the trade name Mellapak® by Sulzer. In addition to the internals mentioned, other suitable internals are known to the person skilled in the art and can also be used. In a particularly preferred embodiment of the present invention, the desorption column comprises a plurality of internals, preferably 2 to 50 internals, particularly preferably 2 to 15 internals.

Step c) of the process according to the invention involves heating the loaded absorption medium in the desorption column by means of a bottom evaporator (SV). The bottom evaporator (SV) is fed with a stream taken from the lower end of the desorption column and, after passing through the bottom evaporator (SV), is returned to the desorption column, thereby degassing at least a portion of the carbon dioxide from the loaded absorption medium and producing a discharged absorption medium (EA).

According to the invention, bottom evaporators are referred to as evaporators that heat the bottom of the desorption column. Such a bottom evaporator is usually located outside the respective desorption column. Since energy, in particular heat, is transferred from one stream to another in bottom evaporators, they act as heat exchangers. The stream to be evaporated, the at least partially loaded absorbent, is withdrawn from the bottom of the desorption column via an outlet and fed to the bottom evaporator. The evaporated stream, optionally with a residual liquid portion, is returned to the respective desorption column in the bottom region via at least one inlet.

Suitable evaporators that can be used as sump evaporators are, for example, natural circulation evaporators, forced circulation evaporators, forced circulation evaporators with expansion, Boiler evaporator, falling-film evaporator, or thin-film evaporator. Natural circulation evaporators and forced circulation evaporators typically use a tube bundle or plate evaporator as the heat exchanger. In addition to the above, any other evaporator design known to those skilled in the art that is suitable for use in a desorption column can also be used.

The desorption in step c) is preferably carried out at a pressure of 1 to 3 bar, particularly preferably at a pressure of 1.2 to 2 bar. The temperature in step c) of the process according to the invention should preferably be in the range of 110 to 140 °C, particularly preferably in the range of 115 to 130 °C.

The aim of desorption is to remove carbon dioxide from the loaded absorption medium BA. This occurs via the elevated temperature. As a result, in step c) a carbon dioxide-rich stream is withdrawn at the top of the desorption column, which preferably contains at least 80 vol.% carbon dioxide, preferably at least 85 vol.% carbon dioxide, particularly preferably at least 90 vol.% carbon dioxide, in each case based on the total volume of the carbon dioxide-rich stream. In addition, a discharged absorption medium EA is obtained, from which a large part, i.e. preferably > 90%, particularly preferably > 99% of the absorbed carbon monoxide has been removed. The discharged absorption medium EA is generally obtained at the bottom of the at least one desorption column.

The discharged absorption medium EA is returned in step d) to the at least one absorption column in step a). The discharged absorption medium is obtained at a temperature in the range of 100 to 140 °C. The high temperature is necessary to remove carbon monoxide from the absorption medium. At this high temperature, the discharged absorption medium cannot be returned to the at least one absorption column in step a). Instead, the discharged absorption medium must be cooled. In the present case, this is achieved by the heat integration according to the invention, in which energy is transferred from EA to a liquid or gaseous heat transfer medium W, thereby forming a heat transfer medium W1 and cooling the discharged absorption medium EA before entering the at least one absorption column.

The transfer of energy, in particular heat energy, from the discharged absorption medium EA to the heat transfer medium W in step d) preferably takes place in a heat exchanger. A direct transfer of energy from the discharged absorption medium EA to the heat transfer medium W takes place. Direct transfer means that the two streams do not directly contact each other, but that energy, in particular heat, is transferred from EA to W without the presence of an additional heat transfer medium.

The energy transfer in step d) can be carried out using heat exchangers known to those skilled in the art. Suitable evaporators that can be used as heat exchangers include, for example, natural circulation evaporators, forced circulation evaporators, forced circulation evaporators with expansion, boiler evaporators, falling film evaporators, or thin-film evaporators. In addition to the aforementioned, Any other type of evaporator known to the person skilled in the art that is suitable for use for the desired preheating may also be used.

A variety of different substances or mixtures can be used as heat transfer media. The heat transfer media W is preferably selected from the group consisting of water; alcohols; alcohol-water mixtures; salt-water solutions; ammonia; mineral oils, such as diesel oils; thermal oils, such as silicone oils; biological oils, such as limonene; and aromatic or aliphatic hydrocarbons, such as dibenzyltoluene. The heat transfer media W is water, methanol, ethanol, propanol, n-pentane, n-butane, n-hexane, n-propane, or ammonia. The heat transfer media W is preferably n-pentane.

If the heat transfer medium W is used in the liquid phase, i.e., a liquid heat transfer medium W, in step d) and energy, preferably thermal energy, is supplied to it in step d), the heat transfer medium W is at least partially evaporated, thereby obtaining an at least partially gaseous heat transfer medium W1. If the heat transfer medium W is used in the gaseous phase, i.e., a gaseous heat transfer medium W, in step d) and energy, preferably thermal energy, is supplied to it in step d), a gaseous heat transfer medium W1 is obtained.

In the context of the present invention, the formulation of liquid heat transfer medium means that > 50 wt.%, further preferably > 55 wt.%, further preferably > 75 wt.%, further preferably > 90 wt.% and particularly preferably > 99 wt.% of the heat transfer medium used in step d) is in the liquid state, in each case based on the total weight of the heat transfer medium used in step d).

In the context of the present invention, the formulation of gaseous heat transfer medium means that > 30 wt.%, further preferably > 50 wt.%, further preferably > 75 wt.%, further preferably > 90 wt.% and particularly preferably > 99 wt.% of the heat transfer medium used in step d) is in the gaseous state, in each case based on the total weight of the heat transfer medium used in step d).

After the described energy transfer in step d), the heat transfer medium W1 has a higher temperature and/or a higher pressure than the heat transfer medium W. In a preferred embodiment of the present invention, W1 has a temperature in the range from 30 °C to 110 °C, preferably in the range from 40 °C to 60 °C. The pressure of W1 is preferably in the range from 0.5 bar to 5 bar, more preferably 1 bar to 4 bar. It goes without saying that the heat transfer medium W1 corresponds to the heat transfer medium W and that W and W1 differ only in their respective pressure and/or temperature and, if W was used as a liquid, in their state of aggregation.

In the subsequent step e), at least a part of the heat transfer medium W1 is compressed, resulting in a heat transfer medium W2 which is more compressed than W1 and has a higher pressure than the Heat transfer medium W1. The pressure of W2 after compression is preferably in the range of 1 bar to 20 bar, preferably 2 bar to 15 bar.

The compression of at least a portion of the heat transfer medium W1 in step e) can be carried out in any desired manner known to the person skilled in the art. For example, the compression can be carried out mechanically and in a single-stage or multi-stage process. In this context, "single-stage" means that compression takes place from one pressure level to another. "Multi-stage" means that compression is first carried out to a pressure level X and then from X to pressure level Y. In multi-stage compression, several compressors of the same design or compressors of different designs can be used. Multi-stage compression can be carried out with one or more compressor machines. The use of single-stage compression or multi-stage compression depends on the compression ratio and thus on the pressure to which the heat transfer medium W1 is to be compressed.

Any compressor known to the person skilled in the art, preferably a mechanical compressor with which gas streams can also be compressed, is suitable as a compressor in the process according to the invention, in particular for compressing the heat transfer medium W1 in step e). Suitable compressors include, for example, single- or multi-stage geared turbocompressors, piston compressors, screw compressors, centrifugal compressors, or axial compressors.

In step h) of the process according to the invention, energy is transferred from the compressed heat transfer medium W2 to the stream in the bottom evaporator SV. As a result of step f), the energy of W2 decreases, so that W2 preferably condenses at least partially. The transfer of energy from W2 to the stream in the bottom evaporator SV, preferably the heating of the stream in the bottom evaporator SV by W2, preferably takes place directly. Direct transfer means that W2 and the stream in SV do not come into direct contact, but that energy, in particular thermal energy, is transferred from W2 to the stream in the SV without the presence of an additional heat transfer medium. The heat transfer devices or heat exchangers familiar to the person skilled in the art, in particular evaporators, can be used as the bottom evaporator SV.

The energy transfer in step f) can be carried out by methods known to those skilled in the art or using heat exchangers known to those skilled in the art. Suitable evaporators that can be used as heat exchangers include, for example, natural circulation evaporators, forced circulation evaporators, forced circulation evaporators with expansion, kettle evaporators, falling-film evaporators, or thin-film evaporators. In addition to the aforementioned evaporators, any other evaporator design known to those skilled in the art that is suitable for use in a distillation column can also be used.

The energy transfer in step f) can be carried out in different ways. In a variant of the process according to the invention, the compressed heat transfer medium W2 itself can be used in the heat exchanger to transfer energy from W2 to the stream in the bottom evaporator Sv. If Since energy is transferred from the heat transfer medium W2 to the stream in the bottom evaporator Sv, some of the absorption media mentioned are disadvantageous. For example, the evaporation temperature of n-butane, ammonia, and propanol k is above the critical point, and sufficient condensation cannot be achieved. However, a specialist would take this into account when selecting the appropriate heat transfer medium based on their usual expertise.

Another variant of the process according to the invention provides that energy is first transferred to another heat transfer medium, such as water. The energy transfer in step f) then occurs in such a way that steam is generated via the compressed heat transfer medium W2 in an evaporator, which steam is used for heating in the bottom evaporator SV. The evaporators mentioned above can be used as evaporators. In this case, the steam is preferably water vapor.

Regardless of whether the energy in step f) is transferred by W2 itself or by the generated steam, W2 or the steam can be used for further preheating of the loaded absorbent BA. This allows for additional energy savings that would otherwise have to be supplied externally.

In a preferred embodiment of the present invention, the heat transfer medium W2 is recycled after the energy transfer in step f) and reused as heat transfer medium W in step d). The heat transfer medium is thus circulated, and only a single heat transfer medium is used in steps d), e), and f).

In a particularly preferred embodiment of the present invention, the heat transfer medium W1 is compressed twice in step e). In the first compression V1, a compressed heat transfer medium W1.1 is produced which has a higher pressure than W1, and in the second compression V2, the compressed heat transfer medium W2 is produced which has a higher pressure than W1.1. W2 is then used for the energy transfer in step f), as already described. Two individual compressors can be used for the double compression. However, the use of a single multi-stage compressor is also possible, with which both compressions V1 and V2 can be carried out independently of one another.

The heat transfer medium W2 is preferably at least partially condensed during the energy transfer in step f). It is further preferred that the at least partially condensed heat transfer medium W2 is fed into a flash container which is operated at the pressure level lying between the two compression stages V1 and V2. Particularly preferably, the flash portion in the flash container is passed as a gas phase between the two compression stages. This allows part of the energy present in the heat transfer medium W2 after the energy transfer in step f) to be used. The flash portion is mixed with the compressed heat transfer medium W1.1, subjected to the second compression V2 and fed to the energy transfer in step f). Only the liquid portion in the flash container is then passed to step d) as heat transfer medium W and passes through steps d), e) and f). The present invention will be described with reference to the drawings described below.

Fig. 1 shows a non-inventive embodiment of the process. The CO2-containing

Raw hydrogen (1) is brought into countercurrent contact with an absorption medium in the first absorption column (2). A gas stream (3) is taken off at the top of the first absorption column (2), passed into the second absorption column (5), and again brought into countercurrent contact with the absorption medium. The processed hydrogen stream (6) is taken off at the top of the second absorption column. The partially loaded absorption medium (7) obtained in the second absorption column is fed to the first distillation column (2). The loaded absorption medium (4) is taken off at the bottom of the column (2), subjected to heat integration in the heat exchanger (8), and thereby heated. Before it is fed into the desorption column (10), it is further heated using low-pressure steam via a preheater (9). In the desorption column (10), the absorption medium is freed of carbon dioxide, and a carbon dioxide-rich stream (15) is taken off at the top of the column (10). Energy is introduced into the system via the bottom evaporator SV (11). The discharged absorption medium (12) is removed from the bottom of the desorption column (10) and transported via a booster pump (13) to the heat exchanger (8) for heat integration. Before being reused in the second absorption column (5), the absorption medium is cooled with cooling water in the heat exchanger (14).

Fig. 2 shows an embodiment of the method according to the invention, which corresponds in large parts to Fig. 1. In addition to the circuitry described in Fig. 1, the thermal energy of the discharged absorption medium is partially utilized using a heat pump. For this purpose, the heat transfer medium W, preferably n-pentane, is at least partially evaporated in the heat exchanger (25). The heat transfer medium is preheated via the heat exchanger (20) and subjected to multi-stage compression in two compressor stages (21, 22). In the heat exchanger (23), heating steam is generated via the heat transfer medium, which is used for heating in the preheater (9) and the bottom evaporator (11). The at least partially condensed steam is fed back into the heat exchanger (23) via a booster pump (26). The heat transfer medium is subjected to an intermediate flash (24). The gas phase generated in the intermediate flash (24) is recirculated to a section between the compressor stages (21 and 22). The liquid portion from the intermediate flash is fed to the heat exchanger (25).

Fig. 3 shows an embodiment of the method according to the invention, which corresponds in large parts to Fig. 1. In addition to the circuitry described in Fig. 1, the thermal energy of the discharged absorption medium is partially utilized using a heat pump. In the present case, the heat transfer medium is used directly as a heating medium. For this purpose, the heat transfer medium W, preferably n-pentane, is at least partially evaporated in the heat exchanger (25). The heat transfer medium is preheated via the heat exchanger (20) and subjected to multi-stage compression in two compressor stages (21, 22). After the first compression, a partial flow of the heat transfer medium can be used for preheating (9). The other part of the heat transfer medium is fed to the second compression stage (22) and then used for heating in the bottom evaporator (11). The following examples are intended to illustrate the invention without limiting its scope of application, which is apparent from the description and the claims.

Examples

The same feed stream is used as the basis for all subsequent examples. The composition of the raw hydrogen stream is considered as follows: 5.2 vol.% CO, 61.9 vol.% H2, 30.7 vol.% CO2, 1.1 vol.% CP, and 1.1 vol.% H2O. The calculations were performed using Aspen Plus® Version 10 and an adapted property model based on operationally validated property data.

Example 1 (not according to the invention)

The simulation was carried out using the process configuration shown in Fig. 1. The following parameters were considered in the simulation. The absorbent (fresh: 15% water, 45% DIPA, and 40% sulfolane) is fed at a rate of 60 t/h into the first desorption column (2), which is operated at a pressure of 17.5 bar abs. The purified raw hydrogen gas (6) is withdrawn from the second absorption column (5) at 17 bar abs and 45°C. The loaded absorbent is withdrawn from the bottom of the first absorption column (2) at approximately 77°C and heated to 102°C in the heat exchanger (8). It is heated to 115°C by the preheater (9). The preheater is operated with 0.9 t/h of low-pressure steam. Energy is introduced into the system via the bottom evaporator (11) on the desorption column (10) using 3.6 t/h of low-pressure steam to provide the required 60 t/h of discharged absorbent (12). Before being reused in the second absorption column (5), the absorbent is heated to the optimal absorption temperature of approximately 44°C using cooling water at the heat exchanger (14). At the heat exchanger (14), 2.3 MW of energy is removed from the system using recooling water. A total of 4.5 t/h of steam (= 2.7 MW of heating capacity) is required to operate the raw hydrogen purification process.

Example 2 (according to the invention)

The simulation was carried out using the process configuration shown in Fig. 2. The following parameters were taken into account in the simulation. During heat integration, n-pentane is evaporated in the heat exchanger (25) at 1.2 bar abs and 40°C. The n-pentane is preheated via the heat exchanger 20 and subjected to multi-stage compression (21, 22) using a machine. This requires an electrical output of 0.9 MW. In the heat exchanger 23, 4.5 t/h of heating steam at 4 bar abs is generated from the upgraded waste heat, which is used to heat the preheater (9) and bottom evaporator. A total of 2.7 MW of heating output (by 4.5 t/h steam) was replaced with 0.9 MW of electrical output. Example 3 (according to the invention)

The simulation was conducted using the process configuration shown in Fig. 2. During heat integration, n-pentane is vaporized in the heat exchanger (25) at 1.2 bar abs and 40°C. The n-pentane is preheated via heat exchanger 20 and subjected to multi-stage compression (21, 22). This requires a total electrical power of 0.8 MW. A total of 2.7 MW of heating power (by 4.5 t/h of steam) was replaced with 0.8 MW of electrical power.

Examples 2 and 3 according to the invention show a process for raw hydrogen gas scrubbing in which steam can be replaced by heat integration. By substituting steam with green

Electricity can be saved by up to 7,740 CO2eqt/a and operating costs can be reduced.

Claims

Patent claims 1 . Process for the processing of raw hydrogen containing more than 50 vol.% hydrogen, less than 10 vol.% carbon monoxide, methane and more than 10 vol.% carbon dioxide, wherein the specified vol.% refers in each case to the total volume of the raw synthesis gas and wherein the process comprises at least the following steps: a) bringing the raw hydrogen into contact with an absorption medium which consists of 10 to 20 wt.% water, 40 to 50 wt.% DIPA and 35 to 45 wt.% sulfolane, wherein the amounts of the three components water, diisopropylamine (DIPA) and sulfolane add up to 100%, in at least one absorption column, whereby at least part of the carbon dioxide passes into the absorption medium and a loaded absorption medium BA is formed and whereby a processed hydrogen stream is obtained which contains at least 75 vol.% hydrogen; b) feeding the loaded absorption medium BA to at least one desorption column, wherein the loaded absorption medium BA is preheated before entering the desorption column; c) heating the loaded absorption medium in the desorption column by means of a bottom evaporator SV, which is fed with a stream taken off at the lower end of the desorption column and, after passing through the bottom evaporator SV, is returned to the desorption column, whereby at least a portion of the carbon dioxide is outgassed from the loaded absorption medium and a discharged absorption medium EA is formed, which is obtained at the bottom of the at least one desorption column; d) returning the discharged absorption medium EA to the at least one absorption column in step a), wherein energy is transferred from EA to a liquid or gaseous heat transfer medium W, whereby a heat transfer medium W1 is formed which has a higher temperature than the heat transfer medium W, and whereby the discharged absorption medium EA is cooled before entering the at least one absorption column; e) compressing at least a portion of the heat transfer medium W1, whereby a compressed heat transfer medium W2 is formed which has a higher pressure than the heat transfer medium W1; and f) transferring energy from the compressed heat carrier W2 to the stream in the sump evaporator SV. 2. Process according to claim 1, wherein step a) is carried out in at least two absorption columns, preferably in exactly two absorption columns. 3. Process according to one of the preceding claims, wherein step a) is operated in countercurrent, i.e. the raw hydrogen and the absorbent are brought into contact with each other in countercurrent. 4. The process according to claim 3, wherein the raw hydrogen is introduced into the lower part of the at least one absorption column and the absorbent is introduced into the upper part of the at least one absorption column. 5. Process according to one of the preceding claims, wherein the heat transfer medium is water, methanol, ethanol, propanol, n-pentane, n-butane, n-hexane, n-propane or ammonia, preferably n-pentane. 6. Method according to one of the preceding claims, wherein the heat transfer medium W2 is returned after the energy transfer in step f) and used again as heat transfer medium W in step d). 7. The process according to claim 2, wherein, when the absorption in step a) is carried out in two absorption columns, the discharged absorbent EA is passed to the second absorption column, where a partially loaded absorbent is formed, which is then passed to the first absorption column, where the loaded absorbent is formed, which is passed for desorption in step c). 8. The process according to claim 7, wherein the raw hydrogen is introduced into the first absorption column. 9. Method according to one of the preceding claims, wherein the preheating of the loaded absorption medium BA takes place in that energy is transferred from the discharged absorption medium EA to the loaded absorption medium BA in a heat exchanger. 10. The method according to any one of the preceding claims, wherein the transfer of energy in step f) is carried out in such a way that steam, preferably water steam, is generated via the compressed heat carrier W2 in an evaporator, which steam is used for heating in the bottom evaporator SV. 11. Method according to one of the preceding claims, wherein the heat transfer medium W1 is compressed twice, wherein in the first compression a compressed heat transfer medium W1 .1 is produced which has a higher pressure than W1 and in the second compression the compressed heat transfer medium W2 is produced which has a higher pressure than W1 .1. 12. The method according to claim 10 or 11, wherein the heat transfer medium W2 condenses at least partially during the energy transfer. 13. The method according to claim 12, wherein the at least partially condensed heat transfer medium W2 is fed into a flash tank which is operated at the pressure level which lies between the two compression stages. 14. The method according to claim 13, wherein the flash portion in the flash container is passed between the two compression stages.