Energy saving method for crude hydrogen treatment

Abstract

The invention relates to a method for treating a crude hydrogen containing at least carbon monoxide, hydrogen, methane and carbon dioxide with an absorbent. The method is characterized in that the energy in the offloaded absorbent is utilized by means of a heat transfer medium in the process to save energy costs and to reduce CO2.

Description

[0001] The subject of this invention is a method for treating crude hydrogen containing at least carbon monoxide, hydrogen, methane, and carbon dioxide using an absorbent. This method is characterized by utilizing the energy in the unloaded absorbent through a heat transfer medium in the process, thereby saving energy costs and reducing CO2.

[0002] Treating crude hydrogen by separating carbon dioxide can be carried out by various methods. In particular, the use of absorbents such as water, physical absorbents like Selexol, or chemical absorbents like Sulfinol is known. Sulfinol can be used to remove acidic components, such as carbon dioxide, from natural gas, pipeline fuel gas, and syngas. Here, acidic components are washed from the crude gas under pressure in an absorption tower using an absorbent formed from sulfolane and diisopropanolamine. In downstream process steps, the acidic gaseous components are discharged from the loaded absorbent.

[0003] Especially when removing gaseous components from the loaded absorbent in a desorption tower, a large amount of energy needs to be supplied from the outside. The commonly used external heat source is heating steam. Therefore, the increase in energy costs has a significant impact on this method. Furthermore, a large amount of CO2 is released during the generation of heating steam.

[0004] The object of this invention is to provide a method for processing crude hydrogen, wherein little or no externally supplied energy is required. Furthermore, a purification method is also intended to be provided, which can be used to reduce CO2.

[0005] The basic objective can be achieved by the method for processing crude hydrogen according to claim 1. Preferred embodiments of this method are specified in the dependent claims.

[0006] The method of the present invention is a method for processing crude hydrogen containing more than 50% by volume of hydrogen, less than 10% by volume of carbon monoxide, methane, and more than 10% by volume of carbon dioxide, wherein the volume percentage data are based on the total volume of crude syngas, and wherein the method includes at least the following steps: a) In at least one absorber, crude hydrogen is contacted with an absorbent consisting of 10 to 20 wt% water, 40 to 50 wt% DIPA and 35 to 45 wt% sulfolane, wherein the sum of the amounts of the three components, water, diisopropylamine (DIPA) and sulfolane, is 100%, thereby transferring at least a portion of the carbon dioxide into the absorbent to form a loaded absorbent BA, and thus obtaining a treated hydrogen stream containing at least 75 vol% hydrogen. b) The loaded absorbent BA is fed into at least one desorption tower, wherein the loaded absorbent BA is preheated before entering the desorption tower; c) The loaded absorbent in the desorption tower is heated by a reboiler SV, which is fed by a stream taken from the bottom of the desorption tower, which re-enters the desorption tower after passing through the reboiler SV, thereby causing at least a portion of the carbon dioxide to escape from the loaded absorbent and forming unloaded absorbent EA. d) Return the unloaded absorbent EA to the at least one absorption tower in step a), wherein energy is transferred from EA to a liquid or gaseous heat transfer medium W, thereby forming a heat transfer medium W1, and thus cooling the unloaded absorbent EA before it enters the at least one absorption tower. e) Compressing at least a portion of the heat transfer medium W1, thereby generating a compressed heat transfer medium W2 at a pressure higher than that of the heat transfer medium W1; and f) The energy in the compressed heat transfer medium W2 is transferred to the feed stream in the reboiler SV.

[0007] The method of this invention is characterized by thermal integration, in which energy in the form of heat is transferred from one part of the method to another. A heat transfer medium is used here. Absorption processes are exothermic, where the absorbed heat is typically extracted from the system via a cooler. In contrast, the method of this invention specifies the utilization of this heat through the use of a heat transfer medium. Here, the absorbed heat is not discharged via cooling water, but is used to evaporate the heat transfer medium, which is then used to heat the reboiler.

[0008] The crude hydrogen used for processing can come from various sources. One possibility is that the crude hydrogen is the necessary excess sulfur-free syngas from a hydroformylation unit. Crude hydrogen can also be taken out as exhaust gas from a steam reformer to adjust the CO content. The crude hydrogen is preferably sulfur-free, i.e., free of sulfur-containing compounds. According to the invention, the crude hydrogen contains more than 50% by volume of hydrogen, preferably more than 55% by volume, more preferably more than 59% by volume, based on the total volume of the crude hydrogen. The amount of carbon dioxide in the crude hydrogen can vary, but is at most 45% by volume, preferably at most 40% by volume, more preferably at most 35% by volume, based on the total volume of the crude hydrogen. Furthermore, the crude syngas contains less than 10% by volume of carbon monoxide, preferably less than 7% by volume, based on the total volume of the crude syngas. The crude syngas also contains more than 10% by volume of carbon dioxide, preferably more than 20% by volume, based on the total volume of the crude syngas.

[0009] In the first step a), crude hydrogen is contacted in at least one absorber with an absorbent consisting of 10 to 20 wt% water, 40 to 50 wt% DIPA and 35 to 45 wt% sulfolane, wherein the sum of the amounts of the three components, water, diisopropylamine (DIPA) and sulfolane, is 100%, thereby transferring at least a portion of the carbon dioxide into the absorbent to form a loaded absorbent BA, and thus obtaining a purified crude hydrogen stream.

[0010] The absorbent comprises at least water, diisopropylamine (DIPA), and sulfolane. In this invention, the absorbent used consists of only these three components: water, diisopropylamine (DIPA), and sulfolane. The absorbent may contain varying amounts of these three components. The absorbent comprises 10 to 20% by weight of water, 40 to 50% by weight of DIPA, and 35 to 45% by weight of sulfolane, based on the total absorbent content. The sum of the amounts of water, diisopropylamine (DIPA), and sulfolane must be 100%.

[0011] The absorption in step a) of the method of the present invention is carried out in at least one absorption tower. However, more than one absorption tower may also be used in step a). According to the present invention, the absorption in step a) is preferably carried out in at least two absorption towers, and more preferably in exactly two absorption towers.

[0012] If the absorption in step a) is carried out in two absorption towers, the unloaded absorbent EA is first fed into the second absorption tower, where a partially loaded absorbent is formed. This partially loaded absorbent is then fed into the first absorption tower, where a loaded absorbent is formed, which is then fed into the desorption process in step c). Preferably, crude hydrogen is first introduced into the first absorption tower and then fed into the second absorption tower. The purified crude hydrogen gas is then removed from the top of the second absorption tower.

[0013] The absorption tower used can be any type of absorption tower known to those skilled in the art. The absorption tower preferably includes internals. Suitable internals include, for example, trays, irregular packing (random packing), or structured packing. Commonly used trays include bubble cap trays, sieve trays, valve trays with fixed or movable valves, tunnel cover trays, or slotted trays. Irregular packing is typically a layer of random packing. Commonly used random packing includes Raschig rings, Pall rings, Bell saddle packing, superring / superring reinforced packing, or Intalox® saddle packing. Structured packing is, for example, sold by Sulzer under the trademark Mellapak®. In addition to the above-mentioned internals, other suitable internals known to those skilled in the art can also be used. In a particularly preferred embodiment of the invention, the absorption tower includes a plurality of internals, preferably 2 to 50 internals, more preferably 2 to 15 internals.

[0014] The absorption in step a) of the method of the present invention is preferably carried out at a pressure of 10 to 40 bar, more preferably at a pressure of 14 to 30 bar. The absorption temperature in step a) is preferably 30 to 80°C, more preferably 35 to 70°C. If the absorption in step a) is carried out in two absorption towers, the pressure and temperature in the two absorption towers are respectively 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 not necessarily the same. This means that the absorption towers can also operate at different pressures and different temperatures.

[0015] More preferably, the absorption in step a) is operated in a counter-current manner, i.e., the crude hydrogen and the absorbent contact each other in a counter-current manner. If there are two or more absorption towers, it is preferable that all absorption towers operate in a counter-current manner. Preferably, the crude hydrogen is introduced into the lower part of the at least one absorption tower, and the absorbent is introduced into the upper part of the at least one absorption tower. At this time, the crude hydrogen flows upward and contacts the downward flowing absorbent. Here, at least some of the carbon dioxide is washed away. Better distribution can be achieved through the internals preferably present in the at least one absorption tower, thereby achieving improved contact between the crude hydrogen and the absorbent.

[0016] In step a), a treated hydrogen stream is obtained, containing at least 75% hydrogen, preferably at least 80% hydrogen, more preferably at least 85% hydrogen, based on the total volume of the treated hydrogen stream. The purified crude hydrogen stream can then be used as a feedstock.

[0017] In step b) of the method of the present invention, the loaded absorbent BA is fed into at least one desorption tower, preferably only a single desorption tower, wherein the loaded absorbent BA is preheated before entering the desorption tower. The temperature of the loaded absorbent BA after absorption is 30 to 80°C, preferably 35 to 70°C. However, the desorption temperature is higher than the absorption temperature. Therefore, it is advantageous to preheat the loaded absorbent BA before it enters the desorption tower, because not all desorption energy must be introduced through the reboiler of the desorption tower.

[0018] The loaded absorbent BA is preferably preheated by transferring energy from the unloaded absorbent EA to the loaded absorbent BA in a heat exchanger. Here, energy is transferred directly from the unloaded absorbent EA to the loaded absorbent BA. Direct transfer means that although the two streams are not in direct contact, energy, especially heat, is transferred from EA to BA without the presence of an additional heat transfer medium.

[0019] The preheating in step b) can be performed using a heat exchanger 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 flash evaporators, kettle evaporators, falling film evaporators, or thin film evaporators. In addition to the evaporators mentioned above, any other evaporator construction type known to those skilled in the art suitable for the required preheating can also be used.

[0020] The separation of at least carbon dioxide from the loaded absorbent is carried out in at least one desorption tower. The desorption tower used can be any type of desorption tower known to those skilled in the art. The desorption tower preferably includes internals. Suitable internals include, for example, trays, irregular packing (random packing), or structured packing. Commonly used trays include bubble cap trays, sieve trays, valve trays with fixed or movable valves, tunnel cover trays, or slotted trays. Irregular packing is typically a random packing bed. Commonly used random packing includes Raschig rings, Pall rings, Bell saddle packing, superring / superring reinforced packing, or Intalox® saddle packing. Structured packing is, for example, sold by Sulzer under the trademark Mellapak®. In addition to the internals described above, other suitable internals known to those skilled in the art can also be used. In a particularly preferred embodiment of the invention, the desorption tower includes a plurality of internals, preferably 2 to 50 internals, more preferably 2 to 15 internals.

[0021] Step c) of the method of the present invention specifies that the loaded absorbent in the desorption tower is heated by a reboiler SV. The reboiler SV is fed by a feed stream taken from the bottom of the desorption tower, which re-enters the desorption tower after passing through the reboiler SV, thereby causing at least a portion of the carbon dioxide to escape from the loaded absorbent and forming unloaded absorbent EA.

[0022] According to the present invention, a reboiler is an evaporator that heats the bottom of a desorption tower. Such reboilers are typically located outside the respective desorption towers. Because energy, particularly heat, is transferred from one feed stream to another within the reboiler, they function as heat transfer devices. The feed stream to be evaporated (at least partially loaded with absorbent) is removed from the bottom of the desorption tower and fed into the reboiler via a removal device. The evaporated feed stream (optionally containing a residual liquid portion) is returned to the bottom region of the respective desorption tower through at least one inlet.

[0023] Suitable evaporators that can be used as reboilers include, for example, natural circulation evaporators, forced circulation evaporators, forced circulation flash evaporators, kettle evaporators, falling film evaporators, or thin film evaporators. In natural circulation and forced circulation evaporators, the heat transfer device typically used in the evaporator is a tube bundle or plate device. In addition to these, any other evaporator construction type suitable for desorption towers known to those skilled in the art can also be used.

[0024] The desorption in step c) is preferably carried out at a pressure of 1 to 3 bar, more preferably at a pressure of 1.2 to 2 bar. The temperature in step c) of the method of the present invention is preferably 110 to 140°C, more preferably 115 to 130°C.

[0025] The purpose of desorption is to remove carbon dioxide from the loaded absorbent BA. This is achieved by increasing the temperature. Therefore, in step c), a carbon dioxide-rich stream is removed from the top of the desorption tower, preferably containing at least 80% by volume of carbon dioxide, more preferably at least 85% by volume of carbon dioxide, and more preferably at least 90% by volume of carbon dioxide, based on the total volume of the carbon dioxide-rich stream, respectively. Furthermore, unloaded absorbent EA is obtained, from which most, preferably >90%, more preferably >99% of the absorbed carbon monoxide is removed. The unloaded absorbent EA is typically obtained at the bottom of the at least one desorption tower.

[0026] In step d), the unloaded absorbent EA is returned to the at least one absorption tower from step a). The temperature of the unloaded absorbent obtained here is 100 to 140°C. High temperature is necessary for removing carbon monoxide from the absorbent. Due to the high temperature, the unloaded absorbent cannot be returned to the at least one absorption tower from step a). Instead, the unloaded absorbent must be cooled. In this example, this is achieved by thermal integration according to the invention, wherein energy is transferred from EA to a liquid or gaseous heat transfer medium W, thereby forming a heat transfer medium W1, which cools the unloaded absorbent EA before it enters the at least one absorption tower.

[0027] In step d), the process of transferring energy, particularly heat, from the unloaded absorbent EA to the heat transfer medium W preferably takes place in a heat exchanger. Here, energy is transferred directly from the unloaded absorbent EA to the heat transfer medium W. Direct transfer means that although the two streams are not in direct contact, energy, especially heat, is transferred from EA to W without the presence of an additional heat transfer medium.

[0028] 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 flash evaporators, kettle evaporators, falling film evaporators, or thin film evaporators. In addition to the above-mentioned evaporators, any other evaporator construction type suitable for the required preheating, known to those skilled in the art, can also be used.

[0029] The heat transfer medium used can be a variety of different substances or mixtures. The heat transfer medium W is preferably selected from: water; alcohol; alcohol-water mixtures; brine solutions; ammonia; mineral oil (e.g., diesel); heat transfer oil (e.g., silicone oil); bio-oil (e.g., limonene); and aromatic or aliphatic hydrocarbons (e.g., dibenzyltoluene). The heat transfer medium W can be water, methanol, ethanol, propanol, n-pentane, n-butane, n-hexane, n-propane, or ammonia. The heat transfer medium W is preferably n-pentane.

[0030] If the heat transfer medium W is used in liquid phase form in step d), i.e., a liquid heat transfer medium W is used, and energy, preferably thermal energy, is supplied to it in step d), then the heat transfer medium W will at least partially evaporate, thereby obtaining a heat transfer medium W1 that is at least partially gaseous. If the heat transfer medium W is used in gaseous phase form in step d), i.e., a gaseous heat transfer medium W is used, and energy, preferably thermal energy, is supplied to it in step d), then a gaseous heat transfer medium W1 is obtained.

[0031] In this invention, the term "liquid heat transfer medium" refers to the heat transfer medium used in step d) having >50% by weight, more preferably >55% by weight, more preferably >75% by weight, more preferably >90% by weight, and more preferably >99% by weight in a liquid state, respectively based on the total weight of the heat transfer medium used in step d).

[0032] In this invention, the term "gaseous heat transfer medium" refers to the heat transfer medium used in step d) having >30% by weight, more preferably >50% by weight, more preferably >75% by weight, more preferably >90% by weight, and more preferably >99% by weight in a gaseous state, respectively, based on the total weight of the heat transfer medium used in step d).

[0033] Following the energy transfer described in step d), the heat transfer medium W1 has an increased temperature and / or increased pressure compared to the heat transfer medium W. In a preferred embodiment of the invention, the temperature of W1 is 30°C to 110°C, preferably 40°C to 60°C. The pressure of W1 is preferably 0.5 bar to 5 bar, preferably 1 bar to 4 bar. Clearly, heat transfer medium W1 corresponds to heat transfer medium W, and the difference between W and W1 lies only in their respective pressures and / or their temperatures, and optionally, if W is used in liquid form, also in their physical state.

[0034] In subsequent step e), at least a portion of the heat transfer medium W1 is compressed, thereby generating a compressed heat transfer medium W2 relative to W1, with a higher pressure than the heat transfer medium W1. The pressure of W2 after compression is preferably from 1 bar to 20 bar, more preferably from 2 bar to 15 bar.

[0035] The compression of at least a portion of the heat transfer medium W1 described in step e) can be performed using any of the methods known to those skilled in the art. For example, compression can be mechanical and performed in single or multiple stages. Single-stage compression here refers to compression from one pressure level to another. Multi-stage compression refers to compression first to pressure level X, and then from X to pressure level Y. In multi-stage compression, multiple compressors of the same or different construction types can be used. Multi-stage compression can be accomplished by one or more compressors. Whether to use single-stage or multi-stage compression depends on the compression ratio, and therefore also on the pressure to which the heat transfer medium W1 should be compressed.

[0036] The compressor suitable for use in the method of the present invention, particularly the compressor for compressing the heat transfer medium W1 in step e), is any compressor known to those skilled in the art, preferably a mechanical compressor, which can also be used to compress airflow. Suitable compressors include, for example, single-stage or multi-stage geared turbine compressors, piston compressors, screw compressors, centrifugal compressors, or axial compressors.

[0037] In step h) of the method of the present invention, energy is transferred from the compressed heat transfer medium W2 to the feed stream in the reboiler SV. Step f) reduces the energy of W2 so that W2 preferably at least partially condenses. The energy transfer from W2 to the feed stream in the reboiler SV, preferably by heating the feed stream in the reboiler SV by W2, is preferably direct. Direct transfer means that although W2 and the feed stream in SV are not in direct contact, energy, especially heat, is transferred from W2 to the feed stream in SV without the presence of an additional heat transfer medium. The reboiler SV used can be a heat transferor or heat exchanger familiar to those skilled in the art, particularly an evaporator.

[0038] The energy transfer in step f) can be achieved by methods known to those skilled in the art or by 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 flash evaporators, kettle evaporators, falling film evaporators, or thin film evaporators. In addition to the evaporators described above, any other evaporator construction types suitable for distillation columns known to those skilled in the art can also be used.

[0039] The energy transfer in step f) can be achieved in different ways. In one variant of the method of the invention, the compressed heat transfer medium W2 itself can be used directly in the heat exchanger to transfer energy from W2 to the feed stream in the reboiler SV. If the energy is transferred from the heat transfer medium W2 to the feed stream in the reboiler SV, certain absorbents mentioned above will be disadvantageous. For example, in the cases of n-butane, ammonia, and propanol, the evaporation temperature is above the critical point, making sufficient condensation impossible. However, those skilled in the art will take this into account when selecting the appropriate heat transfer medium based on their professional knowledge.

[0040] In another variation of the method of the invention, energy is first transferred to another heat transfer medium, such as water. In this case, the energy transfer in step f) is carried out in such a way that steam is generated in an evaporator using a compressed heat transfer medium W2, which is used for heating in the reboiler SV. The evaporator used can be one of the aforementioned evaporators. Here, the steam is preferably water vapor.

[0041] Regardless of whether the energy in step f) comes from W2 itself or is transferred via the generated vapor, the W2 or vapor can be used to further preheat the load of absorbent BA. This also saves energy that would otherwise require an external supply.

[0042] In a preferred embodiment of the invention, the heat transfer medium W2 after energy transfer in step f) is returned and reused as the heat transfer medium W in step d). In this way, the heat transfer medium is circulated, and only a single heat transfer medium is used in steps d), e), and f).

[0043] In a preferred embodiment of the invention, the heat transfer medium W1 is compressed twice in step e). Here, in the first compression V1, a compressed heat transfer medium W1.1 with a pressure higher than W1 is obtained, and in the second compression V2, a compressed heat transfer medium W2 with a pressure higher than W1.1 is obtained. W2 is then used for energy transfer in step f) as described above. Two separate compressors can be used for the two compressions. However, a single multistage compressor can also be used to perform these two compressions V1 and V2 independently of each other.

[0044] During the energy transfer process in step f), the heat transfer medium W2 preferably undergoes at least partial condensation. More preferably, the at least partially condensed heat transfer medium W2 is fed into a flash tank, which operates at the pressure level between the two compression stages V1 and V2. More preferably, the flash distillate in the flash tank is guided in gaseous form between the two compression stages. This allows utilization of a portion of the energy present in the heat transfer medium W2 after the energy transfer in step f). The flash distillate is mixed with the compressed heat transfer medium W1.1, which undergoes a second compression V2, and enters the energy transfer process in step f). Then, only the liquid distillate in the flash tank is fed as the heat transfer medium W into step d), and passes through steps d), e), and f).

[0045] The present invention will be described in conjunction with the following figures.

[0046] Figure 1A non-inventive embodiment of the method is shown. Crude hydrogen (1) containing CO2 is contacted countercurrently with the absorbent in a first absorption tower (2). A stream (3) is drawn from the top of the first absorption tower (2) and enters a second absorption tower (5), where it again contacts the absorbent countercurrently. The treated hydrogen stream (6) is drawn from the top of the second absorption tower. The partially loaded absorbent (7) obtained in the second absorption tower is sent to a first distillation tower (2). The loaded absorbent (4) is drawn from the bottom of the tower (2), thermally integrated in a heat exchanger (8), and thus heated. Before entering the desorption tower (10), it is further heated using low-pressure steam via a preheater (9). In the desorption tower (10), carbon dioxide is removed from the absorbent, and a carbon dioxide-rich stream (15) is drawn from the top (10) of the tower. Energy is introduced into the system via a reboiler SV (11). The unloaded absorbent (12) is removed from the bottom of the distillation column (10) and fed into the heat exchanger (8) via the pressure boosting pump (13) for thermal integration. The absorbent is cooled with cooling water in the heat exchanger (14) before being used again in the second absorption column (5).

[0047] Figure 2 This invention illustrates an embodiment of the method, most of which is similar to... Figure 1 Correspondingly. Besides Figure 1 In addition to the circuit diagram described herein, the thermal energy from the unloaded absorbent is also partially utilized by 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 in the heat exchanger (20) and undergoes multi-stage compression in two compression stages (21, 22). Heating vapor is generated by the heat transfer medium in the heat exchanger (23), which is used for heating in the preheater (9) and reboiler (11). The vapor, which is at least partially condensed, is returned to the heat exchanger (23) by a pressure boosting pump (26). The heat transfer medium undergoes intermediate flash evaporation (24). The gas phase obtained in the intermediate flash evaporation (24) is returned between the compression stages (21 and 22). The liquid portion produced by the intermediate flash evaporation is fed into the heat exchanger (25).

[0048] Figure 3 This invention illustrates an embodiment of the method, most of which is similar to... Figure 1 Correspondingly. Besides Figure 1 In addition to the circuit diagram described herein, the thermal energy from the unloaded absorbent becomes partially available via a heat pump. In this example, the heat transfer medium is used directly as the 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 undergoes multi-stage compression in two compression stages (21, 22). After the first compression, the sub-stream of the heat transfer medium can be used for preheating (9). Another portion of the heat transfer medium enters the second compression stage (22) and is then used for heating in the reboiler (11).

[0049] The following examples are intended to illustrate the invention, but do not limit the scope of application defined in the specification and claims. Example

[0050] All the following examples use the same feed stream as a basis. The composition of the crude hydrogen stream is considered as follows: 5.2 vol% CO, 61.9 vol% H2, 30.7 vol% CO2, 1.1 vol% CH4, and 1.1 vol% H2O. Calculations were performed using Aspen Plus® version 10 and a material data model adapted based on run-validated material data.

[0051] Example 1 (not the present invention) The simulation adopts Figure 1 The process flow diagram shown is used. The following parameters are considered in the simulation. The absorbent (fresh: 15% water, 45% DIPA and 40% sulfolane) enters the first desorption tower (2) at a flow rate of 60 t / h, which operates at an absolute pressure of 17.5 bar. The purified crude hydrogen gas (6) is withdrawn from the second absorption tower (5) at an absolute pressure of 17 bar and a temperature of 45°C. The loaded absorbent is withdrawn from the bottom of the first absorption tower (2) at approximately 77°C and heated to 102°C in a heat exchanger (8). It is then heated to 115°C by a preheater (9). The preheater operates using low-pressure steam at a rate of 0.9 t / h. Energy is introduced into the system using low-pressure steam at a rate of 3.6 t / h through a reboiler (11) at the desorption tower (10) to provide the required 60 t / h of unloaded absorbent (12). Before being reused in the second absorption tower (5), the absorbent is cooled to an optimal absorption temperature of approximately 44°C in the heat transfer unit (14) using cooling water. 2.3 MW is removed from the system at the heat transfer unit (14) via reflux cooling water. A total of 4.5 t / h of steam (= 2.7 MW of thermal power) is required to operate the crude hydrogen purification.

[0052] Example 2 (according to the present invention) The simulation adopts Figure 2 The process flow diagram shown is used. The following parameters are considered in the simulation. During the thermal integration process, n-pentane evaporates in heat exchanger (25) at an absolute pressure of 1.2 bar and a temperature of 40°C. The n-pentane is preheated by heat transferr 20 and then subjected to multi-stage compression (21, 22) by the machine. This requires 0.9 MW of electrical power. In heat transferr 23, the enhanced waste heat is used to generate 4.5 t / h of heating steam at an absolute pressure of 4 bar, which is used to heat the preheater (9) and the reboiler. A total of 2.7 MW of thermal power (generated by 4.5 t / h of steam) is replaced by 0.9 MW of electrical power.

[0053] Example 3 (according to the present invention) The simulation adopts Figure 2The process flow diagram is shown. During thermal integration, n-pentane evaporates in heat exchanger (25) at an absolute pressure of 1.2 bar and a temperature of 40°C. The n-pentane is preheated by heat transferr 20 and undergoes multi-stage compression (21, 22). A total of 0.8 MW of electrical power is required for this. A total of 2.7 MW of thermal power (generated by 4.5 t / h of steam) is replaced by 0.8 MW of electrical power.

[0054] Embodiments 2 and 3 of the present invention illustrate methods for scrubbing crude hydrogen gas, wherein steam can be replaced by thermal integration. Replacing steam with green electricity can reduce CO2 by up to 7740%. 2eq t / a, and reduce operating costs. Claims (as amended under Article 19 of the Treaty) 1. A method for processing crude hydrogen containing more than 50% by volume hydrogen, less than 10% by volume carbon monoxide, methane, and more than 10% by volume carbon dioxide, wherein the volume percentage data are based on the total volume of crude syngas, and wherein the method comprises at least the following steps: a) In at least one absorber, crude hydrogen is contacted with an absorbent consisting of 10 to 20 wt% water, 40 to 50 wt% DIPA and 35 to 45 wt% sulfolane, wherein the sum of the amounts of the three components, water, diisopropylamine (DIPA) and sulfolane, is 100%, thereby transferring at least a portion of the carbon dioxide into the absorbent to form a loaded absorbent BA, and thus obtaining a treated hydrogen stream containing at least 75 vol% hydrogen. b) The loaded absorbent BA is fed into at least one desorption tower, wherein the loaded absorbent BA is preheated before entering the desorption tower; c) The loaded absorbent in the desorption tower is heated by a reboiler SV, which is fed by a stream taken from the bottom of the desorption tower, which re-enters the desorption tower after passing through the reboiler SV, thereby causing at least a portion of the carbon dioxide to escape from the loaded absorbent and forming the unloaded absorbent EA at the bottom of the at least one desorption tower. d) Return the unloaded absorbent EA to the at least one absorption tower in step a), wherein energy is transferred from EA to the liquid or gaseous heat transfer medium W, such that the temperature of the formed heat transfer medium W1 is higher than that of the heat transfer medium W, thereby cooling the unloaded absorbent EA before it enters the at least one absorption tower. e) Compressing at least a portion of the heat transfer medium W1 to produce a compressed heat transfer medium W2 with a pressure higher than that of the heat transfer medium W1, wherein the heat transfer medium W1 is compressed twice, wherein the pressure of the compressed heat transfer medium W1.1 obtained in the first compression is higher than that of W1, and the pressure of the compressed heat transfer medium W2 obtained in the second compression is higher than that of W1.1; and f) Transferring energy from the compressed heat transfer medium W2 to the feed stream in the reboiler SV, wherein the energy transfer in step f) is carried out by generating steam, preferably water vapor, in the evaporator through the compressed heat transfer medium W2 for heating in the reboiler SV. 2. The method according to claim 1, wherein step a) is carried out in at least two absorption towers, preferably in exactly two absorption towers. 3. The method according to any one of the preceding claims, wherein step a) is operated in a countercurrent manner, i.e., the crude hydrogen and the absorbent are in countercurrent contact with each other. 4. The method according to claim 3, wherein crude hydrogen is introduced into the lower part of the at least one absorption tower and absorbent is introduced into the upper part of the at least one absorption tower. 5. The method according to any 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. The method according to any one of the preceding claims, wherein the heat transfer medium W2 is returned and reused as the heat transfer medium W in step d) after energy transfer in step f). 7. The method of claim 2, wherein when the absorption in step a) is carried out in two absorption towers, the unloaded absorbent EA is fed into the second absorption tower, where a partially loaded absorbent is formed, which is then fed into the first absorption tower, where a loaded absorbent is formed, which is then fed into the desorption in step c). 8. The method of claim 7, wherein crude hydrogen is introduced into the first absorption tower. 9. The method according to any one of the preceding claims, wherein the loaded absorbent BA is preheated by transferring energy from the unloaded absorbent EA to the loaded absorbent BA in a heat exchanger. 10. The method of claim 1, wherein the heat transfer medium W2 condenses at least partially during energy transfer. 11. The method of claim 10, wherein at least partially condensed heat transfer medium W2 is fed into a flash tank, which operates at the pressure level between the two compression stages. 12. The method of claim 11, wherein the flash distillate in the flash tank is directed between two compression stages.

Claims

1. A method for processing crude hydrogen containing more than 50% by volume hydrogen, less than 10% by volume carbon monoxide, methane, and more than 10% by volume carbon dioxide, wherein the volume percentage data are based on the total volume of crude syngas, and wherein the method comprises at least the following steps: a) In at least one absorber, crude hydrogen is contacted with an absorbent consisting of 10 to 20 wt% water, 40 to 50 wt% DIPA and 35 to 45 wt% sulfolane, wherein the sum of the amounts of the three components, water, diisopropylamine (DIPA) and sulfolane, is 100%, thereby transferring at least a portion of the carbon dioxide into the absorbent to form a loaded absorbent BA, and thus obtaining a treated hydrogen stream containing at least 75 vol% hydrogen. b) The loaded absorbent BA is fed into at least one desorption tower, wherein the loaded absorbent BA is preheated before entering the desorption tower; c) The loaded absorbent in the desorption tower is heated by a reboiler SV, which is fed by a stream taken from the bottom of the desorption tower, which re-enters the desorption tower after passing through the reboiler SV, thereby causing at least a portion of the carbon dioxide to escape from the loaded absorbent and forming the unloaded absorbent EA at the bottom of the at least one desorption tower. d) Return the unloaded absorbent EA to the at least one absorption tower in step a), wherein energy is transferred from EA to the liquid or gaseous heat transfer medium W, such that the temperature of the formed heat transfer medium W1 is higher than that of the heat transfer medium W, thereby cooling the unloaded absorbent EA before it enters the at least one absorption tower. e) Compress at least a portion of the heat transfer medium W1 to generate a compressed heat transfer medium W2 with a pressure higher than that of the heat transfer medium W1. and f) The energy in the compressed heat transfer medium W2 is transferred to the feed stream in the reboiler SV.

2. The method according to claim 1, wherein step a) is carried out in at least two absorption towers, preferably in exactly two absorption towers.

3. The method according to any one of the preceding claims, wherein step a) is operated in a countercurrent manner, i.e., the crude hydrogen and the absorbent are in countercurrent contact with each other.

4. The method according to claim 3, wherein crude hydrogen is introduced into the lower part of the at least one absorption tower and absorbent is introduced into the upper part of the at least one absorption tower.

5. The method according to any 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. The method according to any one of the preceding claims, wherein the heat transfer medium W2 is returned and reused as the heat transfer medium W in step d) after energy transfer in step f).

7. The method of claim 2, wherein when the absorption in step a) is carried out in two absorption towers, the unloaded absorbent EA is fed into the second absorption tower, where a partially loaded absorbent is formed, which is then fed into the first absorption tower, where a loaded absorbent is formed, which is then fed into the desorption in step c).

8. The method of claim 7, wherein crude hydrogen is introduced into the first absorption tower.

9. The method according to any one of the preceding claims, wherein the loaded absorbent BA is preheated by transferring energy from the unloaded absorbent EA to the loaded absorbent BA in a heat exchanger.

10. The method according to any one of the preceding claims, wherein the energy transfer in step f) is carried out in such a manner as to generate steam, preferably water vapor, in an evaporator via a compressed heat transfer medium W2, which is used for heating in a reboiler SV.

11. The method according to any one of the preceding claims, wherein the heat transfer medium W1 is compressed twice, wherein the pressure of the compressed heat transfer medium W1.1 obtained in the first compression is higher than that of W1, and the pressure of the compressed heat transfer medium W2 obtained in the second compression is higher than that of W1.

1.

12. The method according to claim 10 or 11, wherein the heat transfer medium W2 condenses at least partially during energy transfer.

13. The method of claim 12, wherein at least partially condensed heat transfer medium W2 is fed into a flash tank, which operates at the pressure level between the two compression stages.

14. The method of claim 13, wherein the flash distillate in the flash tank is directed between two compression stages.

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