Purification system and method for industrial hydrogen-rich gas

Abstract

The invention relates to a purification system and method for industrial hydrogen-rich gas, and belongs to the technical field of gas purification. The system comprises a raw material pipeline; a pretreatment unit; the pretreatment unit comprises a macromolecule removal unit and a desulfurization unit which are communicated in sequence, and the macromolecule removal unit is communicated with a raw material pipeline; the pressure swing adsorption unit is communicated with the desulfurization unit and / or the raw material pipeline; the temperature swing adsorption unit is communicated with the pressure swing adsorption unit; the product pipeline is communicated with the pressure swing adsorption unit and / or the temperature swing adsorption unit; by integrating the pretreatment unit, the pressure swing adsorption unit and the temperature swing adsorption unit, the recovery rate of hydrogen can be increased. Meanwhile, the problem of unstable fuel hydrogen quality caused by fluctuation of raw material gas components and reduction of long-term operation performance of the adsorbent can be further solved through temperature swing adsorption. In addition, the combination of pretreatment, pressure swing adsorption and temperature swing adsorption can be flexibly adjusted according to actual needs so as to meet the hydrogen purity requirement.

Description

Technical Field

[0001] The present application relates to the technical field of gas purification, and in particular to a purification system and method for industrial hydrogen-rich gas. Background Art

[0002] Hydrogen is a common chemical raw material, widely used in petrochemical, metallurgy, aerospace, glass, semiconductor and other industries. In recent years, with the development of hydrogen energy, hydrogen as an energy source has also been rapidly developed in the fields of hydrogen vehicles and hydrogen power generation. Hydrogen comes from various sources, including hydrogen production devices such as coal-to-hydrogen, natural gas-to-hydrogen, and coke oven gas-to-hydrogen, as well as hydrogen-rich gas produced as a byproduct of industrial devices such as refinery reforming devices, ethylene devices, and propane dehydrogenation devices.

[0004] Common impurities in industrial hydrogen-rich gas include C2-C6, CH4, N2, Ar, CO, CO2, H2S, etc. In industry, CO is toxic to many catalysts, such as ammonia synthesis catalysts, polypropylene catalysts and polyethylene catalysts. Ammonia synthesis catalysts are usually required to be removed to below 5ppmv, and polyolefin catalysts are usually below 1ppmv. At the same time, hydrogen is used as fuel gas for fuel cells, and its quality determines the performance of fuel cells. Today, on a global scale, fuel cell technology is mainly based on proton exchange membrane fuel cells (PEMFC), which have the most mature technology and the highest degree of industrialization. On the electrode catalyst of PEMFC, since the precious metal Pt supported as a catalyst is very sensitive to CO and sulfur, when there are too many trace impurities in hydrogen, compounds containing C and S have irreversible poisoning effects on the electrodes, so the requirements for impurities in hydrogen are very high. Among them, carbon-containing compounds such as CO, CO2, and CH4 can cause irreversible carbon corrosion and other permanent damage to battery electrodes. Sulfides can not only have a serious impact on the performance of the battery anode, but may also cause significant damage to the performance of the battery cathode. After a trace amount of NH3 enters the membrane, it will react with H + The reaction produces NH4 + , while NH4 + H that can replace the electrolyte membrane + , which has an irreversible impact on battery performance. In particular, precious metal electrodes such as platinum and palladium have a greater adsorption effect on CO than on H2, so that CO adsorbed on the platinum electrode hinders the electrochemical reaction of H2, reduces energy conversion efficiency, shortens battery life, and even completely deactivates. Therefore, hydrogen fuel cells have very high requirements for hydrogen quality. According to the requirements of GB / T 37244-2018 "Hydrogen Fuel for Proton Exchange Membrane Fuel Cell Vehicles", the CO content in the fuel hydrogen is less than 0.2ppm, and the total sulfur content (measured in H2S) is less than 4ppb. Therefore, for these application scenarios, it is necessary not only to purify the hydrogen, but also to ensure that the content of other impurities such as CO meets the requirements.

[0005] In industry, commonly used methods for hydrogen purification include cryogenic separation, organic polymer membrane separation, adsorption (including pressure swing adsorption and temperature swing adsorption), etc. Among them, the purity of hydrogen produced by cryogenic separation and organic polymer membrane separation is generally below 99 mol%, which is suitable for occasions with low purity requirements. The adsorption method can obtain 99 to 99.999 mol% hydrogen, which has a wide range of applications. Therefore, for applications with high purity requirements and stringent impurity indicators, adsorption methods are often used, especially pressure swing adsorption (PSA). Molecular sieves are often used to remove CO in PSA. Conventional molecular sieve adsorbents have a low separation coefficient and a limited adsorption capacity. In order to ensure that CO meets the standard, it is often necessary to increase the amount of adsorbent used, sacrificing the recovery rate of the product hydrogen. At the same time, it is difficult to solve the potential risk of unstable fuel hydrogen quality caused by fluctuations in the raw gas components and the decline in the long-term operating performance of the adsorbent. Summary of the invention

[0006] The present application provides a purification system and method for industrial hydrogen-rich gas to improve the recovery rate of hydrogen.

[0007] In a first aspect, the present application provides a purification system for industrial hydrogen-rich gas, the system comprising:

[0008] Raw material pipeline to provide industrial hydrogen-rich gas;

[0009] A pretreatment unit for removing C5+ macromolecules and at least part of sulfides in the industrial hydrogen-rich gas; the pretreatment unit comprises a macromolecule removal unit for removing C5+ macromolecules and a desulfurization unit for removing sulfides, which are connected in sequence, and the macromolecule removal unit is connected to the raw material pipeline to receive the industrial hydrogen-rich gas;

[0010] A pressure swing adsorption unit, used to remove alkanes, nitrogen, carbon dioxide, sulfides and at least part of carbon monoxide in the industrial hydrogen-rich gas; the pressure swing adsorption unit is connected to the desulfurization unit and / or the raw material pipeline to receive the industrial hydrogen-rich gas;

[0011] A temperature swing adsorption unit, used to remove the remaining carbon monoxide and sulfide in the industrial hydrogen-rich gas; the temperature swing adsorption unit is connected to the pressure swing adsorption unit;

[0012] The product pipeline is used to discharge the purified hydrogen, and the product pipeline is connected to the pressure swing adsorption unit and / or the temperature swing adsorption unit.

[0013] As an optional embodiment, the macromolecular removal unit includes at least two purification towers connected in parallel.

[0014] As an optional embodiment, the macromolecular removal unit includes a first regeneration pipeline, one end of which is connected to the pressure swing adsorption unit, and the other end of which is connected to the purification tower, so as to use the gas treated by the pressure swing adsorption unit as the regeneration gas.

[0015] As an optional implementation, the first regeneration pipeline is provided with a first heater for heating the regeneration gas.

[0016] As an optional implementation manner, the number of the purification towers is an even number.

[0017] As an optional embodiment, the temperature swing adsorption unit includes at least two TSA adsorption towers.

[0018] As an optional embodiment, the temperature swing adsorption unit includes a second regeneration pipeline, one end of the second regeneration pipeline is connected to a nitrogen supply pipeline, and the other end of the second regeneration pipeline is connected to the TSA adsorption tower to use nitrogen as the regeneration gas.

[0019] As an optional embodiment, the second regeneration pipeline is provided with a second heater for heating the regeneration gas; and / or

[0020] The number of the TSA adsorption towers is an even number.

[0021] In a second aspect, the present application provides a method for purifying industrial hydrogen-rich gas, using the purification system described in the first aspect, the method comprising:

[0022] Pressure swing adsorption of industrial hydrogen-rich gas;

[0023] The industrial hydrogen-rich gas is subjected to pretreatment and / or temperature swing adsorption; the pretreatment comprises removing C5+ macromolecules and at least part of sulfides in the industrial hydrogen-rich gas.

[0024] As an optional implementation, the pretreatment of the industrial hydrogen-rich gas is performed before pressure swing adsorption.

[0025] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0026] The system provided in the embodiment of the present application can improve the recovery rate of hydrogen by 2% to 5% compared with the conventional pressure swing adsorption scheme for purifying hydrogen by integrating the pretreatment unit, the pressure swing adsorption unit and the temperature swing adsorption unit. At the same time, temperature swing adsorption can further improve the problem of unstable fuel hydrogen quality caused by fluctuations in raw gas components and degradation of the long-term operating performance of the adsorbent. In addition, the combination of pretreatment, pressure swing adsorption and temperature swing adsorption can be flexibly adjusted according to actual needs to meet the hydrogen purity requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 A schematic diagram of the structure of the system provided in the embodiment of the present application;

[0030] Figure 2 A schematic diagram of the structure of a pre-processing unit provided in an embodiment of the present application;

[0031] Figure 3 A schematic diagram of the structure of a temperature-swing adsorption unit provided in an embodiment of the present application.

[0032] Figure numerals: 1-raw material pipeline, 2-pretreatment unit, 21-purification tower, 22-first regeneration pipeline, 23-first heater, 3-pressure swing adsorption unit, 4-temperature swing adsorption unit, 41-TSA adsorption tower, 42-second regeneration pipeline, 43-second heater, 5-product pipeline. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0035] Industrial byproducts of hydrogen-rich gas are of high quality and large in total volume, such as refinery reforming hydrogen, ethane to ethylene byproduct hydrogen, natural gas steam reforming hydrogen production, etc. If these hydrogen-rich gases can be effectively utilized, it will be of great significance to promote the green and low-carbon development of enterprises and further improve economic benefits. Common impurities in industrial hydrogen-rich gas are mainly C2~C6, CH4, N2, Ar, CO, CO2, H2S, etc. As the fuel gas of fuel cells, the quality of hydrogen determines the performance of fuel cells. Nowadays, on a global scale, fuel cell technology is mainly based on proton exchange membrane fuel cells (PEMFC), which have the most mature technology and the highest degree of industrialization. On the electrode catalyst of PEMFC, the precious metal Pt supported as a catalyst is very sensitive to CO and sulfur. When there are too many trace impurities in hydrogen, compounds containing C and S have irreversible poisoning effects on the electrodes, so the requirements for impurities in hydrogen are very high. Among them, carbon-containing compounds such as CO, CO2, and CH4 will cause irreversible carbon corrosion and other permanent damage to the battery electrodes. Sulfide can not only seriously affect the performance of the battery anode, but also cause significant damage to the battery cathode performance. After a trace amount of NH3 enters the membrane, it will react with H + The reaction produces NH4 + , while NH4 + H that can replace the electrolyte membrane + , which has an irreversible impact on battery performance. In particular, precious metal electrodes such as platinum and palladium have a greater adsorption effect on CO than on H2, so that CO adsorbed on the platinum electrode hinders the electrochemical reaction of H2, reduces energy conversion efficiency, shortens battery life, and even completely deactivates. Therefore, hydrogen fuel cells have very high requirements for hydrogen quality. According to the requirements of GB / T 37244-2018 "Fuel Hydrogen for Proton Exchange Membrane Fuel Cell Vehicles", the CO content in the fuel hydrogen is less than 0.2ppm, and the total sulfur content (measured in H2S) is less than 4ppb. Therefore, the invention intends to invent a hydrogen purification system to purify industrial rich hydrogen to meet the hydrogen needs of fuel cells.

[0036] Figure 1 A schematic diagram of the structure of the system provided in the embodiment of the present application, such as Figure 1 As shown, an embodiment of the present application provides a purification system for industrial hydrogen-rich gas, the system comprising:

[0037] Raw material pipeline to provide industrial hydrogen-rich gas;

[0038] A pretreatment unit for removing C5+ macromolecules and at least part of sulfides in the industrial hydrogen-rich gas; the pretreatment unit comprises a macromolecule removal unit for removing C5+ macromolecules and a desulfurization unit for removing sulfides, the macromolecule removal unit being connected to the raw material pipeline to receive the industrial hydrogen-rich gas;

[0039] A pressure swing adsorption unit, used to remove alkanes, nitrogen, carbon dioxide, sulfides and at least part of carbon monoxide in the industrial hydrogen-rich gas; the pressure swing adsorption unit is connected to the desulfurization unit and / or the raw material pipeline to receive the industrial hydrogen-rich gas;

[0040] A temperature swing adsorption unit, used to remove the remaining carbon monoxide and sulfide in the industrial hydrogen-rich gas; the temperature swing adsorption unit is connected to the pressure swing adsorption unit;

[0041] The product pipeline is used to discharge the purified hydrogen, and the product pipeline is connected to the pressure swing adsorption unit and / or the temperature swing adsorption unit.

[0042] Figure 2 A schematic diagram of the structure of the preprocessing unit provided in the embodiment of the present application is shown in FIG. Figure 2 As shown, in some embodiments, the macromolecular removal unit includes at least two parallel purification towers. The macromolecular removal unit includes a first regeneration pipeline, one end of the first regeneration pipeline is connected to the pressure swing adsorption unit, and the other end of the first regeneration pipeline is connected to the purification tower, so as to use the gas treated by the pressure swing adsorption unit as the regeneration gas. The first regeneration pipeline is provided with a first heater for heating the regeneration gas. The pretreatment unit is fully integrated with the pressure swing adsorption unit, and the desorbed gas of the pressure swing adsorption is used to pre-treat the regeneration of the adsorbent, thereby reducing the loss in the regeneration process and improving the hydrogen recovery rate.

[0043] Furthermore, the number of the purification towers is an even number; illustratively, the number of the purification towers may be 2, 4, 6, 8 or 10, etc.

[0044] Specifically, the pretreatment unit removes macromolecular impurities such as C5+ using a two-tower temperature swing adsorption process, one of which is for adsorption and the other for regeneration, and the two towers are used alternately. The purification tower process operation is controlled by a sequential control program, with normal temperature and high pressure adsorption and low pressure and high temperature desorption. The desorption pressure is 0.3MPaG and the desorption temperature is 160°C. The regenerated gas uses the desorbed gas from the downstream PSA, and there is no need to remove the outlet gas or nitrogen from the C5+ purification tower as regeneration gas, which can reduce raw material losses and does not introduce other impurities. The desulfurization of the desulfurization unit adopts catalytic hydrolysis to convert carbonyl sulfide (COS) into H2S at room temperature, and then removes H2S through the fine desulfurizer zinc oxide.

[0045] Figure 3 A schematic diagram of the structure of the temperature swing adsorption unit provided in the embodiment of the present application is shown in FIG. Figure 3As shown, in some embodiments, the temperature swing adsorption unit includes at least two TSA adsorption towers. The temperature swing adsorption unit includes a second regeneration pipeline, one end of the second regeneration pipeline is connected to the nitrogen supply pipeline, and the other end of the second regeneration pipeline is connected to the TSA adsorption tower to use nitrogen as the regeneration gas. A second heater is provided on the second regeneration pipeline to heat the regeneration gas. The second heater can be selected from an electric heater. Temperature swing adsorption (TSA) adopts an integrated indirect heat exchange regeneration method, nitrogen is used as the regeneration heating gas, and the adsorbent is heated and desorbed, and a small amount of product gas is used as a purge gas to bring the desorbed gas out of the adsorption tower. Reduce the loss in the regeneration process, ensure product quality, and improve the adsorbent regeneration effect and hydrogen recovery rate.

[0046] Further, the number of TSA adsorption towers is an even number; illustratively, the number of TSA adsorption towers can be 2, 4, 6, 8 or 10, etc.

[0047] Specifically, the adsorbent used in the TSA adsorption tower adopts the complex adsorption method. CO and the adsorbent form a metal carbonyl complex at room temperature and high pressure, thereby removing CO. Complex adsorption is an adsorption effect between physical adsorption and chemical adsorption, and has the advantages of reversible adsorption-desorption and high selectivity.

[0048] In some embodiments, the pressure swing adsorption unit includes at least two PSA adsorption towers. Further, the number of PSA adsorption towers is an even number; illustratively, the number of PSA adsorption towers can be 2, 4, 6, 8 or 10, etc.

[0049] This system integrates the pretreatment unit, pressure swing adsorption unit and temperature swing adsorption unit. First, the pretreatment unit is used to remove C5+ and other macromolecular impurities and most sulfides in the raw gas. Then, the pressure swing adsorption (PSA) unit is used to remove alkanes, nitrogen, carbon dioxide, sulfides and most CO in the by-product gas. Finally, the temperature swing adsorption (TSA) unit is used to deeply remove the remaining trace CO and further ensure the removal quality of sulfides. And without changing the process flow, the hydrogen can be purified to 99.999vol% by adjusting the adsorption cycle and sequential control time of PSA, meeting the requirements of high-purity hydrogen.

[0050] In addition, different unit combinations and customized process routes can be made according to different impurity types of hydrogen-rich gas. For example, for the requirement that the CO content of fuel hydrogen is less than 0.2ppm, a two-step removal method is adopted: the first step is to purify the hydrogen to a purity of more than 99.99vol% through PSA, and remove CO to less than 5ppm; the second step is to further remove CO by TSA, and the CO content in the hydrogen out of TSA is less than 0.2ppm.

[0051] Based on a general inventive concept, an embodiment of the present application also provides a method for purifying industrial hydrogen-rich gas, using the purification system provided above, the method comprising: performing pressure swing adsorption on the industrial hydrogen-rich gas; performing pretreatment and / or temperature swing adsorption on the industrial hydrogen-rich gas; the pretreatment comprises removing C5+ macromolecules and at least part of the sulfides in the industrial hydrogen-rich gas.

[0052] The method is implemented based on the above system. The specific content of the system can refer to the above embodiment. Since the method adopts part or all of the technical solutions of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described one by one here.

[0053] In some embodiments, the pretreatment of the industrial hydrogen-rich gas is performed before pressure swing adsorption.

[0054] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0055] Example 1

[0056] The composition, temperature and pressure of the hydrogen-rich gas produced as a by-product of a refinery reforming unit are shown in Table 1.

[0057] Table 1

[0058]

[0059]

[0060] In view of the impurity characteristics of this hydrogen-rich gas, a crude hydrogen pretreatment module and a PSA purification module are used to produce qualified fuel hydrogen, the specifications of which meet the requirements of GB / T 37244-2018 "Fuel Hydrogen for Proton Exchange Membrane Fuel Cell Vehicles". The details are as follows:

[0061] The removal of C5+ in the pretreatment module adopts a temperature swing adsorption process. The adsorbent adsorbs C5+ at room temperature, and the adsorbed C5+ is desorbed from the adsorbent by increasing the temperature. At the same time, the adsorbent is regenerated, and then cooled to the adsorption temperature to enter the next adsorption cycle. The temperature swing adsorption process for removing C5+ adopts a two-tower process, one tower for adsorption and one tower for regeneration, and the two towers are used alternately. Each adsorption tower needs to go through the steps of adsorption, reverse pressure release, temperature desorption, cooling, and pressure increase in one cycle. The adsorption towers are staggered in the program arrangement to ensure continuous input of crude hydrogen and continuous output of C5+ degassing gas. The following takes one of the adsorption towers as an example to illustrate the various operating steps:

[0062] a. Adsorption

[0063] The crude hydrogen enters the C5+ removal purification tower from the bottom of the adsorption tower, and the trace C5+ in the gas is adsorbed by the adsorbent, and other components flow out of the adsorption tower from the top of the tower. After the predetermined adsorption time, when the adsorption front of C5+ in the adsorption tower reaches a certain position of the adsorption tower, the raw gas feed valve and the adsorption tail gas outlet valve of the adsorption tower are closed, the adsorption tower stops the adsorption step and begins to enter the regeneration stage.

[0064] b. Reverse pressure release

[0065] After the adsorbent is saturated with adsorption, the gas in the adsorption tower is discharged to 0.02MPag in the opposite direction of the intake air, and the gas is discharged into the waste gas treatment network in the plant area.

[0066] c. Desorption by heating

[0067] The desorbed gas from the pressure swing adsorption process is heated to 160°C by a heat exchanger, and then enters the adsorption tower from the top of the tower to heat the adsorbent, causing the adsorbed C5+ to be desorbed from the adsorbent, and then flows out of the adsorption tower from the bottom of the tower and enters the waste gas treatment network in the plant area.

[0068] d. Cooling

[0069] After the adsorbent is heated and desorbed completely, the heat exchange is stopped and the desorbed gas from the pressure swing adsorption module is still used to enter the adsorption tower from the top of the tower to cool it down to 40°C.

[0070] e. Final pressure

[0071] The pressure of the adsorption tower after regeneration is slightly positive. After the adsorbent is regenerated, part of the product gas produced by another adsorption tower is used to increase the pressure of the tower to the adsorption pressure.

[0072] At this point, the adsorption tower has completed a complete adsorption-regeneration cycle and is ready for the next cycle. The two adsorption towers perform the above steps alternately.

[0073] The crude hydrogen after removing C5+ enters the desulfurization part in the pretreatment module. First, COS is converted into H2S by a COS hydrolyzer, and then the H2S is removed by a fine desulfurizer, effectively protecting the adsorbent of the subsequent PSA purification module.

[0074] The main reactions of desulfurization are:

[0075]

[0076] ZnO+H2S→ZnS+H2O

[0077] The operating temperature of desulfurization is room temperature and the operating pressure is about 2MPaG.

[0078] The gas from the crude hydrogen pretreatment module enters the pressure swing adsorption (PSA) purification module. The desulfurized gas enters the PSA adsorption tower, the product gas is discharged from the top of the adsorption tower, and the desorbed gas is discharged from the bottom of the adsorption tower and sent to the crude hydrogen pretreatment module. The PSA purification module separates H2 from other impurity components such as CH4 and N2 to obtain hydrogen product gas.

[0079] The PSA purification module includes 8 adsorption towers, which work alternately to achieve the purpose of continuous separation and purification of H2. In one cycle, each adsorption tower must go through the following steps: adsorption, pressure equalization and pressure reduction, forward placement, reverse placement, flushing, pressure equalization and pressure increase, and final pressure filling. The following takes an adsorption tower as an example to illustrate the various operating steps:

[0080] a. Adsorption

[0081] The desulfurized gas is sent to the PSA adsorption tower. Under the predetermined adsorption pressure, the impurities in the raw gas are adsorbed by the special adsorbent, and H2 flows out from the top of the adsorption tower as the product gas. When the front of the impurity mass transfer zone in the adsorption tower reaches the predetermined position of the adsorption tower, the raw gas inlet valve and the adsorption tail gas outlet valve of the adsorption tower are closed, the adsorption tower stops the adsorption step and starts the regeneration process.

[0082] b. Pressure equalization and pressure reduction

[0083] After the adsorption step is completed, the adsorption tower is connected to the adsorption tower at low pressure in sequence to recover the useful components in the dead space of the adsorption tower.

[0084] c. Place in order

[0085] After the pressure equalization and pressure reduction step is completed, the adsorption tower performs multiple forward pressure release processes to the forward gas release buffer tank to reduce the pressure of the adsorption tower, and the forward gas release serves as the regeneration flushing gas for other adsorption towers.

[0086] d. Reverse

[0087] After the forward release step is completed, the adsorption front of the impurities approaches the outlet of the adsorption tower, and the reverse release begins to reduce the pressure of the adsorption tower to near normal pressure. The reverse release process can also partially desorb the impurities adsorbed by the adsorbent.

[0088] e. Rinse

[0089] After the reverse discharge is completed, in order to effectively regenerate the adsorbent, the adsorption tower is reversely flushed using the forward discharge gas in the forward discharge gas buffer tank to completely desorb the adsorbent.

[0090] f. Voltage balancing and boosting

[0091] After the flushing step is completed, the pressure of the adsorption tower is increased in sequence by using the higher pressure gas from other adsorption towers to increase the pressure of the adsorption tower gradually.

[0092] g. Final boost

[0093] The adsorption tower that has undergone the above pressure equalization and pressure increase steps has not yet reached the predetermined adsorption pressure. In order to enable the adsorption tower to smoothly switch to the next adsorption, the adsorption tower is finally pressurized with product H2 to raise the pressure of the adsorption tower to the predetermined adsorption pressure.

[0094] At this point, the adsorption tower has completed a complete adsorption-regeneration cycle and is ready for the next cycle. Each adsorption tower alternately performs the above steps, matching and coordinating operations to ensure that the entire device operates smoothly and obtains hydrogen products that meet the requirements.

[0095] Example 2

[0096] The composition, temperature and pressure of the hydrogen-rich gas produced as a by-product of an ethane-to-ethylene unit are shown in Table 2.

[0097] Table 2

[0098]

[0099] In view of the impurity characteristics of this hydrogen-rich gas, PSA purification module and TSA CO removal module are used to produce qualified fuel hydrogen, the specifications of which meet the requirements of GB / T 37244-2018 "Fuel Hydrogen for Proton Exchange Membrane Fuel Cell Vehicles". The details are as follows:

[0100] The process flow of the hydrogen-rich gas entering the pressure swing adsorption (PSA) purification module is the same as that in Example 1.

[0101] The gas from the PSA purification module enters the TSA fine CO removal module, which deeply removes CO and further ensures the removal quality of H2S. TSA adopts a two-tower process, one for adsorption and one for regeneration, and the two towers are used alternately. Each adsorption tower needs to go through the steps of adsorption, reverse decompression, temperature desorption, cooling, and pressure increase in one cycle. The adsorption towers are staggered in the program arrangement to ensure continuous input of raw gas and continuous output of product gas. The following takes an adsorption tower as an example to illustrate the various operation steps:

[0102] a. Adsorption

[0103] The gas from the PSA module enters the TSA adsorption tower from the bottom of the adsorption tower, and the trace CO and H2S in the gas are adsorbed by the adsorbent, and H2 flows out of the adsorption tower from the top of the tower. After the predetermined adsorption time, when the adsorption front of CO and H2S in the adsorption tower reaches a certain position of the adsorption tower, the raw gas feed valve and the adsorption tail gas outlet valve of the adsorption tower are closed, the adsorption tower stops the adsorption step and starts to enter the regeneration stage.

[0104] b. Reverse pressure release

[0105] After the adsorbent is saturated with adsorption, the gas in the adsorption tower is discharged to 0.02MPaG in the opposite direction of the intake air, and the gas is discharged into the waste gas treatment network in the plant area.

[0106] c. Desorption by heating

[0107] The low-pressure nitrogen from the low-pressure nitrogen pipeline network is used as the regeneration heating gas, and after being heated to 180°C by an electric heater, it enters the heat exchange pipe in the adsorption tower from the top of the tower to heat the adsorbent, so that the adsorbed CO is desorbed from the adsorbent. A small amount of product gas from the outlet of the other adsorption tower is used as the purge gas to reversely purge the adsorption tower from the top of the tower, and the desorbed gas is taken out of the adsorption tower from the bottom of the tower and enters the fuel gas pipeline network in the plant area.

[0108] d. Cooling

[0109] After the adsorbent is heated and desorbed completely, the heat exchange is stopped and low-pressure nitrogen is still used to enter the adsorption tower from the top of the tower to cool it down to 40°C.

[0110] e. Final pressure

[0111] After the adsorbent is regenerated, part of the product gas produced by another adsorption tower is used to pressurize the tower to the adsorption pressure.

[0112] At this point, the adsorption tower has completed a complete adsorption-regeneration cycle and is ready for the next cycle. Each adsorption tower alternately performs the above steps, matching and coordinating operations to ensure that the entire device operates smoothly and obtains hydrogen products that meet the requirements.

[0113] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0114] In this application, unless otherwise specified, directional words such as "upper" and "lower" used refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of this application, the terms "include", "comprise", etc. mean "including but not limited to".

[0115] In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, wherein a, b, c can be single or multiple respectively.

[0116] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A purification system for industrial hydrogen-rich gas, characterized in that: The system comprises: Raw material pipeline to provide industrial hydrogen-rich gas; A pretreatment unit for removing C5+ macromolecules and at least part of sulfides in the industrial hydrogen-rich gas; the pretreatment unit comprises a macromolecule removal unit for removing C5+ macromolecules and a desulfurization unit for removing sulfides, which are connected in sequence, and the macromolecule removal unit is connected to the raw material pipeline to receive the industrial hydrogen-rich gas; A pressure swing adsorption unit, used to remove alkanes, nitrogen, carbon dioxide, sulfides and at least part of carbon monoxide in the industrial hydrogen-rich gas; the pressure swing adsorption unit is connected to the desulfurization unit and / or the raw material pipeline to receive the industrial hydrogen-rich gas; A temperature swing adsorption unit, used to remove the remaining carbon monoxide and sulfide in the industrial hydrogen-rich gas; the temperature swing adsorption unit is connected to the pressure swing adsorption unit; The product pipeline is used to discharge the purified hydrogen, and the product pipeline is connected to the pressure swing adsorption unit and / or the temperature swing adsorption unit.

2. The purification system for industrial hydrogen-rich gas according to claim 1, characterized in that: The macromolecular removal unit comprises at least two purification towers connected in parallel.

3. The purification system for industrial hydrogen-rich gas according to claim 2, characterized in that: The macromolecular removal unit comprises a first regeneration pipeline, one end of which is connected to the pressure swing adsorption unit, and the other end of which is connected to the purification tower, so as to use the gas treated by the pressure swing adsorption unit as the regeneration gas.

4. The purification system for industrial hydrogen-rich gas according to claim 3, characterized in that: The first regeneration pipeline is provided with a first heater for heating the regeneration gas.

5. The purification system for industrial hydrogen-rich gas according to claim 2, characterized in that: The number of the purification towers is an even number.

6. The purification system for industrial hydrogen-rich gas according to claim 1, characterized in that: The temperature swing adsorption unit includes at least two TSA adsorption towers.

7. The purification system for industrial hydrogen-rich gas according to claim 6, characterized in that: The temperature swing adsorption unit comprises a second regeneration pipeline, one end of the second regeneration pipeline is connected to a nitrogen supply pipeline, and the other end of the second regeneration pipeline is connected to the TSA adsorption tower to use nitrogen as the regeneration gas.

8. The purification system for industrial hydrogen-rich gas according to claim 7, characterized in that: The second regeneration pipeline is provided with a second heater for heating the regeneration gas; and / or The number of the TSA adsorption towers is an even number.

9. A method for purifying industrial hydrogen-rich gas, characterized in that: Using the purification system according to any one of claims 1 to 8, the method comprises: Pressure swing adsorption of industrial hydrogen-rich gas; The industrial hydrogen-rich gas is subjected to pretreatment and / or temperature swing adsorption; the pretreatment comprises removing C5+ macromolecules and at least part of sulfides in the industrial hydrogen-rich gas.

10. The method for purifying industrial hydrogen-rich gas according to claim 9, characterized in that: The pretreatment of the industrial hydrogen-rich gas is carried out before pressure swing adsorption.

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