Integrated treatment method for hydrogen-containing industrial tail gas purification and carbon resource recovery

Abstract

This invention discloses an integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources, relating to the field of hydrogen energy comprehensive utilization technology. Specifically, it is an integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources, comprising: compressing and dehydrating industrial by-product hydrogen feed gas containing impurities; removing heavy impurities such as hydrogen and carbon dioxide through a first temperature-switching adsorption tower; removing light impurities such as hydrogen and carbon dioxide through a second temperature-switching adsorption tower to obtain crude hydrogen intermediate gas; separating hydrogen-rich permeate gas and hydrogen-rich retentate gas through a membrane separation unit; further purifying the hydrogen-rich permeate gas through a pressure swing adsorption tower group to obtain high-purity hydrogen; combining the retentate gas with the regeneration gas from the two temperature-switching adsorption towers, and converting it into hydrogen ions through catalytic conversion, then cooling and liquefying it to obtain a high-purity liquid product, with the uncondensed gas being recovered as fuel. This process can simultaneously achieve efficient purification and capture of industrial by-product hydrogen.

Description

Technical Field

[0001] This invention relates to the field of hydrogen energy comprehensive utilization technology, specifically an integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources. Background Technology

[0002] As the global energy structure transitions towards a low-carbon model, hydrogen energy, due to its clean and efficient characteristics, has become an important alternative to fossil fuels. However, current industrial hydrogen production still relies heavily on fossil fuel reforming (accounting for over 95%), resulting in high carbon emission intensity. In contrast, industrial by-product hydrogen, as a byproduct of chemical and oil refining processes, has a significant cost advantage (only 30%-50% of that produced from fossil fuels). However, its large-scale application has long been limited by insufficient purity (typically only 70%-90%) and complex impurity composition.

[0003] Typical sources of industrial by-product hydrogen include ammonia synthesis off-gas, refinery dry gas, chlor-alkali tail gas, and propane dehydrogenation tail gas. Direct emission of these feedstock gases not only wastes resources but also exacerbates the greenhouse effect (e.g., in ammonia synthesis off-gas). (The concentration can be as high as 30%). Therefore, developing an integrated system of efficient purification technology and carbon capture process is key to realizing the high-value utilization of industrial by-product hydrogen.

[0004] In existing technologies, the purification of industrial by-product hydrogen mainly employs physical absorption methods (such as low-temperature methanol washing), chemical absorption methods (such as amine absorption), and pressure swing adsorption (PSA) technology. Among these, PSA is widely used due to its simple operation and low energy consumption; however, traditional PSA has limited removal efficiency for polar impurities such as COS and H2S, requiring additional desulfurization equipment (such as iron oxide desulfurizing agents), resulting in a lengthy process. Furthermore, PSA has limitations in removing polar impurities such as COS and H2S. , The separation effect of weakly adsorbed components is poor, making it difficult to meet the stringent requirements for hydrogen (purity ≥99.97%) for fuel cells.

[0005] In CO2 capture, while post-combustion capture technologies (such as amine absorption) are mature, they suffer from problems such as solvent degradation and equipment corrosion. However, membrane separation coupled with catalytic conversion technology for hydrogen-rich systems can simultaneously achieve H2 purification and… Enrichment is possible, but existing membrane materials (such as polydimethylsiloxane) are prone to swelling under high pressure, and... / The selectivity (usually <50) is insufficient to meet the requirements for high-purity separation.

[0006] More importantly, traditional processes often employ a segmented design of "purification first, then collection," resulting in high equipment investment and significant energy loss. For example, a refinery using an "amine decarbonization + PSA hydrogen extraction" process has a combined energy consumption of 8-10 kWh / Nm³. ,and The capture rate is only 60%-70%. Therefore, developing integrated processes that combine high selectivity and low energy consumption has become the core direction for breaking through the bottleneck of industrial by-product hydrogen application.

[0007] In summary, there is a need for an integrated process that can simultaneously address the removal of multiple impurities, the preparation of high-purity H2, and the efficient capture of CO2, in order to promote the green and large-scale utilization of industrial by-product hydrogen. Summary of the Invention

[0008] The purpose of this invention is to provide an integrated treatment method for the purification of hydrogen-containing industrial tail gas and the recovery of carbon resources. By organically combining the purification of industrial by-product hydrogen with carbon dioxide capture, impurities such as sulfides, hydrocarbons, and inert gases in the raw gas are efficiently removed, thereby obtaining high-purity hydrogen products. At the same time, the carbon-containing gas generated during the purification process is converted into high-value-added liquid carbon dioxide products through catalytic conversion and cryogenic separation, and resource recovery is achieved. This achieves the dual goals of hydrogen production and carbon emission reduction, improving the economic efficiency and environmental benefits of the process.

[0009] To achieve the above objectives, the present invention provides the following technical solution: an integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources, comprising the following steps: (1) Containing , The industrial by-product hydrogen feed gas containing impurities is compressed and dehydrated to obtain pretreated gas. This step aims to provide preliminary physical treatment for industrial by-product hydrogen feedstock gas, which has complex origins and fluctuating composition, to meet the requirements of subsequent deep purification processes. First, a multi-stage compressor is used to increase the feedstock gas pressure to the operating pressure required for subsequent stages, while simultaneously achieving centralized gas delivery. Then, a combination of cooling separation and molecular sieve adsorption is employed to remove free water and most of the saturated water vapor from the gas, preventing hydrate formation and corrosion of equipment due to acidic gases dissolving in water. This also creates a low-humidity environment for the subsequent temperature-switching adsorption process, ensuring efficient utilization and long-term operation of the adsorbent.

[0010] (2) The pretreated gas is introduced into the first temperature-switching adsorption tower, and adsorption is performed to remove the gas under the set temperature conditions. , , After removing moisture, the gas is purified by removing heavy impurities; This step primarily utilizes the strong adsorption capacity of a specific adsorbent for highly polar, high-boiling-point impurities containing sulfur, nitrogen, and oxygen to achieve deep desulfurization and ammonia removal from the gas. Under specific intermediate-temperature operating conditions, the adsorbent preferentially captures COS (carbonyl sulfide), which has a poisoning effect on subsequent catalysts. and alkaline Simultaneously, trace amounts of moisture are removed. This process effectively solves the problem of downstream catalyst poisoning caused by the difficulty in removing COS in traditional processes, significantly improves the purification level of the feed gas, and provides qualified feed gas for membrane separation and pressure swing adsorption processes.

[0011] (3) The purified gas, after being de-impure, is passed into a second temperature-switching adsorption tower, where it is adsorbed and removed from the gas under set temperature conditions. , and some This yields crude hydrogen intermediate gas; This step aims to remove heavy gas components that significantly affect hydrogen purity through physical adsorption, thereby reducing the load on the subsequent high-pressure membrane separation system and minimizing hydrogen loss. Within a set temperature range, the adsorbent... , and some Gases exhibit high adsorption capacity, while those with high adsorption capacity exhibit high adsorption capacity. The adsorption capacity is extremely low. Through this selective adsorption process, the content of inert components in the feed gas is significantly reduced, resulting in the initial enrichment of hydrogen concentration entering the membrane separation unit, optimizing the operating conditions of the membrane separation, and improving the hydrogen recovery efficiency.

[0012] (4) The crude hydrogen intermediate gas is introduced into the membrane separation unit, and the difference in gas permeation rate is used to separate the hydrogen-rich intermediate gas into a membrane separation product. Permeable side gas and rich in and the gas trapped on the side containing residual impurities; This step utilizes the difference in dissolution and diffusion rates of gas molecules within the membrane material to achieve rapid hydrogen concentration. Under high pressure differential, H2 molecules with smaller diameters and higher permeability preferentially permeate through the membrane wall into the permeate side, while larger molecules with lower permeability... Residual impurities that were not completely adsorbed are retained on the pore side. This process not only achieves efficient separation of hydrogen from other gases, but also directly produces a high concentration of hydrogen-rich gas, while simultaneously generating a high concentration of... Logistics provides a convenient separation source for subsequent carbon capture and utilization (CCU) processes, enabling pre-separation for resource recovery.

[0013] (5) The rich The permeate-side gas is fed into the pressure swing adsorption tower group, and residual trace impurities are adsorbed through periodic pressure changes, ultimately yielding high-purity product hydrogen. This step, as the final refining stage of the entire process, utilizes the periodic pressure fluctuations within the adsorption tower to desorb and release trace impurities by leveraging the varying adsorption capacity of the adsorbent for these impurities under different pressures. Adsorption is completed under high pressure, and regeneration is completed under low pressure, achieving continuous production through multi-tower switching. This process effectively removes residual trace impurities from the permeate gas, ensuring that the final product is ultra-high purity hydrogen that meets national standards, satisfying the needs of fuel cells or high-end industrial applications.

[0014] (6) The gas trapped on the side is combined with the regenerated desorbed gas from the first and second temperature-switching adsorption towers and then introduced into the catalytic conversion reactor. Under the action of the catalyst, the residual gas is converted into a gas. Transform into The reacted gas mixture was then cooled and liquefied, separating the liquid phase. The product recovers and reuses uncondensed gas as fuel gas.

[0015] This step establishes a complete carbon dioxide capture and resource recovery chain. First, it involves... The highly toxic mixture It is converted into an easily processed form through catalytic hydrogenation. This eliminated safety risks and improved the utilization rate of carbon atoms. Subsequently, using... Its easily liquefiable physical property allows it to be condensed and separated into a high-purity liquid state through a refrigeration system. The remaining non-condensable gases have a high calorific value and can be recycled as fuel gas within the factory, replacing some of the purchased energy, thereby minimizing waste gas emissions and achieving cascaded energy utilization.

[0016] Furthermore, in step (2), the operating temperature of the first variable temperature adsorption tower is 80-150℃, and the regeneration temperature is 180-250℃.

[0017] This clause specifies the temperature control range of the first variable-temperature adsorption tower, aiming to balance the adsorption capacity and kinetic performance of the adsorbent. At lower operating temperatures, the adsorbent has a stronger affinity for polar impurity molecules, resulting in more thorough adsorption; while at higher regeneration temperatures, sufficient energy is provided for impurity molecules to detach from the adsorption sites, ensuring complete regeneration and cycle life of the adsorbent. This temperature range is designed with full consideration of the thermal stability of the adsorbent and the energy efficiency of impurity desorption.

[0018] Furthermore, in step (3), the operating temperature of the second temperature-switching adsorption tower is 80-150℃, and the regeneration temperature is 180-250℃.

[0019] This clause specifies the temperature parameters for the second variable-temperature adsorption tower, primarily targeting the separation characteristics of non-polar or weakly polar macromolecular gases. Within this temperature range, the adsorbent... , and The selective adsorption of gases of type 2 exhibits the best effect, effectively distinguishing the differences in physical properties between these gases and H2. A reasonable regeneration temperature setting ensures the structural stability of the adsorbent bed during the depressurization and heating process, preventing damage to the adsorbent micropores caused by high temperatures and ensuring the separation efficiency and reliability of the device during long-term operation.

[0020] Furthermore, in step (4), the membrane material used in the membrane separation unit is a polyimide or polysulfone hollow fiber membrane, and the operating pressure is 1.0-3.0 MPa.

[0021] This clause defines the core materials and key operating parameters for membrane separation technology. Polyimide and polysulfone materials are particularly suitable for applications involving [missing information - likely related to chemical stability, mechanical strength, and high throughput]. It separates complex industrial gases from sulfides. Hollow fiber membrane modules offer the advantage of high packing density, enabling large-scale gas processing within a small footprint. The set operating pressure range provides sufficient drive to achieve considerable hydrogen recovery rates while avoiding membrane module damage or shortened lifespan due to excessive pressure differentials.

[0022] Furthermore, in step (5), the operating pressure of the pressure swing adsorption tower group is 1.5-4.0 MPa, and the adsorption time is 2-10 minutes.

[0023] This clause defines the pressure and time windows for the pressure swing adsorption (PSA) hydrogen refining process. Higher operating pressures help improve the purity and recovery rate of the hydrogen product, but excessively high pressures increase equipment investment and energy consumption; lower adsorption times are beneficial for increasing the gas throughput, but may affect product purity. The selection of this parameter range represents an optimal balance point determined after comprehensively considering factors such as hydrogen purity indicators, equipment processing capacity, and valve switching frequency, aiming to achieve dual optimization of product quality and production intensity.

[0024] Furthermore, in step (6), the catalytic conversion reactor is filled with a copper-based catalyst, the reaction temperature is 200-350℃, and the reaction pressure is atmospheric pressure to 1.0MPa.

[0025] This clause specifies the exhaust gas... Technical pathways and operating conditions for conversion. The effects of copper-based catalysts at low temperatures. Oxidation reactions exhibit high reactivity and selectivity, efficiently converting toxic carbon monoxide into non-toxic carbon dioxide. The established mild reaction temperature and low-pressure operating conditions not only reduce the material requirements and energy consumption of the reactor but also help suppress the intense exothermic reactions such as methanation, ensuring the safety and economy of the production process.

[0026] Further, in step (6), the liquid... The purity of the product is no less than 99.9%.

[0027] This clause establishes the quality standards for liquid carbon dioxide products. Liquid carbon dioxide with a purity of 99.9% or higher is permitted. It belongs to the superior grade of food or industrial grade and can be directly applied in fields such as welding protection, food processing, and carbonated beverage preparation. This high standard has driven the refined design of the front-end purification process, ensuring the capture of high-quality products. The extremely low impurity content enhances the product's added value and market competitiveness.

[0028] Furthermore, in steps (2) and (3), both the first and second temperature-switching adsorption towers employ at least two adsorption towers connected in parallel to achieve continuous operation.

[0029] This clause emphasizes the engineering configuration principles of the adsorption unit. A dual-tower or multi-tower parallel switching mode is adopted, where when one adsorption tower is in adsorption operation, one or more other towers are in regeneration or pressure equalization standby mode. This design cleverly utilizes the cyclical characteristics of the adsorption process, overcoming the drawback of single-tower operation requiring interruption of gas intake, ensuring the continuity of feed gas processing, and meeting the stringent requirements of industrial production for stable gas supply and stable gas pressure.

[0030] Furthermore, in step (5), the oil rich in... The gas is also introduced into step (6) for CO2 capture.

[0031] This clause reflects the design concept of system integration optimization. The tail gas produced during the pressure swing adsorption (PSA) hydrogen purification process contains a high concentration of... Direct emission of carbon dioxide would waste carbon resources. By integrating this exhaust gas into the catalytic conversion and liquefaction unit, the entire process achieves complete carbon capture. This not only significantly improves the overall carbon capture rate and reduces total carbon emissions, but also maximizes the value of every gas stream in the system.

[0032] Furthermore, the industrial by-product hydrogen feed gas is selected from one or more of the following: synthetic ammonia off-gas, refinery dry gas, chlor-alkali tail gas, and propane dehydrogenation tail gas.

[0033] This clause defines the scope of application and feedstock adaptability of this integrated process. The listed synthetic ammonia off-gas and refinery dry gas contain abundant hydrogen resources, but also contain complex impurities, making it difficult to achieve cost-effective and efficient purification using traditional single purification methods. This process features a modular design tailored to the characteristics of these typical industrial by-product hydrogens, enabling flexible handling of feedstock gases from different sources and with varying compositions. It possesses broad industry applicability and promising prospects for widespread adoption.

[0034] This invention provides an integrated treatment method for purifying hydrogen-containing industrial waste gas and recovering carbon resources, which has the following beneficial effects: 1. Achieving high-purity hydrogen and high-value Simultaneous and efficient recycling This process utilizes a three-stage coupling technology of "temperature swing adsorption + membrane separation + pressure swing adsorption" to obtain industrial-grade high-purity hydrogen with a purity ≥99.9% (meeting the needs of high-end fields such as fuel cells and electronics), while simultaneously reducing the content of hydrogen containing... The stagnant gas is catalytically converted and cryogenically liquefied to produce food / industrial grade liquid. (Purity ≥ 99.9%), solving the problem of traditional hydrogen production processes focusing only on hydrogen recovery while neglecting other aspects. The pain points of resource utilization have enabled the high-value utilization of carbon and hydrogen resources in by-product gas, significantly improving overall economic benefits.

[0035] 2. Synergistic removal of multiple pollutants ensures long-term stable operation of the system.

[0036] The first temperature-controlled adsorption tower is specifically designed to remove... , , Highly corrosive / toxic impurities are further removed by a second temperature-controlled adsorption tower. , , By eliminating difficult-to-separate impurities and combining them with the high selectivity of membrane separation for H2, the poisoning and clogging of these impurities on subsequent membrane modules, pressure swing adsorbents, and catalytic conversion catalysts are avoided from the source. This significantly reduces the frequency of equipment maintenance, extends the service life of core units, and ensures continuous and stable operation of the device.

[0037] 3. Optimized process design significantly reduces overall energy consumption and operating costs.

[0038] The system employs a tiered separation model combining temperature-switching adsorption, membrane separation, and pressure-switching adsorption. This leverages the unique removal capabilities of each unit for specific impurities, reducing the processing load on individual units: temperature-switching adsorption removes heavy impurities at higher temperatures, while membrane separation achieves removal at lower pressures. and The initial separation and deep purification by pressure swing adsorption under high pressure avoid the high energy consumption of full high pressure or full high temperature operation; at the same time, the combined treatment of retentate gas and regenerated gas and the reuse of uncondensed fuel gas further reduce the consumption of raw material gas and carbon emissions, achieving energy saving and consumption reduction.

[0039] 4. Highly adaptable and capable of processing various complex industrial by-product hydrogen feedstocks.

[0040] The process addresses the significant differences in impurity composition among by-product hydrogen from various sources, including synthetic ammonia off-gas, refinery dry gas, chlor-alkali tail gas, and propane dehydrogenation tail gas. It achieves this through flexible temperature control via temperature-switching adsorption and selective matching of membrane materials (e.g., polyimide membranes for specific applications). / With its high separation coefficient, it enables universal processing of various types of raw gas without requiring significant equipment modifications for different gas sources, thus greatly expanding the application scenarios of the process and improving market adaptability.

[0041] 5. Significant environmental benefits, contributing to the achievement of "dual carbon" targets.

[0042] This process not only converts low-value industrial by-product hydrogen into high-purity hydrogen products, but also reduces hydrogen that would otherwise be directly emitted into the atmosphere. Capturing and utilizing the fuel gas in liquid form significantly reduces greenhouse gas emissions. At the same time, the reuse of uncondensed fuel gas further reduces fossil fuel consumption, forming a closed loop of "hydrogen production-hydrogen extraction-carbon capture-energy saving," which aligns with the trend of green chemical development and provides a replicable technological path for carbon emission reduction in the industrial sector. Attached Figure Description

[0043] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0044] Figure 1 This is a flowchart illustrating the overall process of this invention. Figure 2 This is a flowchart of the temperature-switching adsorption (TSA) subsystem of the present invention; Figure 3 This is a flowchart of the membrane separation and pressure swing adsorption (PSA) subsystem of the present invention; Figure 4 For the present invention Flowchart of the capture and conversion subsystem; Figure 5 This is a diagram illustrating the key parameters of the present invention. Detailed Implementation

[0045] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] How to use: Step 1: Raw material pretreatment The industrial by-product hydrogen feedstock gas is first compressed to increase the gas pressure to meet the requirements of subsequent processes. The gas is then dehydrated and dried to remove free water, yielding pretreated gas.

[0048] Step 2: Deep removal of heavy impurities

[0049] The pretreated gas is fed into the first temperature-switched adsorption tower. This tower operates at a temperature between 80°C and 150°C, selectively adsorbing and removing carbonyl sulfide, hydrogen sulfide, ammonia, and residual moisture from the gas, thus obtaining purified gas free of heavy impurities. Once the adsorption tower reaches adsorption saturation, it switches to regeneration mode, where desorption occurs at a high temperature of 180°C to 250°C, causing the impurities to desorb and be discharged from the system.

[0050] Step 3: Removal of light hydrocarbons and nitrogen

[0051] The purified gas obtained in the previous step, free of heavy impurities, is then fed into the second temperature-switched adsorption tower. This tower also operates at a temperature of 80°C to 150°C, and its main function is to adsorb and remove methane, carbon monoxide, and some nitrogen, producing crude hydrogen intermediate gas. This tower also employs at least two adsorption towers connected in parallel to ensure continuous production. After saturation, regeneration and desorption are carried out at 180°C to 250°C.

[0052] Step 4: Membrane pre-separation

[0053] A crude hydrogen intermediate gas is introduced into the membrane separation unit. This unit typically uses a hollow fiber membrane made of polyimide or polysulfone and operates at a pressure of 1.0 MPa to 3.0 MPa. Preliminary separation is achieved by utilizing the significant difference in permeation rates between hydrogen and other gases in the membrane material: the hydrogen-rich gas permeates through the membrane and becomes the permeate-side gas, while the gas rich in carbon dioxide and residual impurities is retained on the retainer side.

[0054] Step 5: Pressure Swing Adsorption Refining

[0055] The permeate-side gas is fed into a pressure swing adsorption (PSA) tower array. This array operates at pressures ranging from 1.5 MPa to 4.0 MPa, using periodic pressure fluctuations (adsorption times typically 2 to 10 minutes) to deeply adsorb residual trace impurities, thereby producing the final high-purity product, hydrogen. Simultaneously, the carbon dioxide-rich gas released from the PSA tower array is collected and sent downstream for further processing.

[0056] Step 6: Carbon Dioxide Capture and Conversion

[0057] The gas trapped on the membrane separation unit is combined with the regeneration desorption gas from the first and second temperature-switching adsorption towers and introduced into the catalytic conversion reactor. The reactor is filled with a copper-based catalyst, and at a reaction temperature of 200°C to 350°C and a pressure of atmospheric pressure to 1.0 MPa, residual carbon monoxide (CO) in the gas is converted into carbon dioxide. The resulting mixture is cooled and liquefied to separate liquid carbon dioxide with a purity of not less than 99.9%, which can be sold directly as a product or stored. The unliquefied residual gas, due to its high calorific value, is recovered as fuel gas for internal system heating or other applications.

[0058] Example: Example 1: Treatment process for ammonia synthesis off-gas This example uses the purge gas from a large-scale synthetic ammonia plant as feedstock. This feedstock gas mainly contains... (approximately 60%) (approximately 20%) (Approximately 15%) and a small amount (approximately 2%) (Approximately 1.5%) and trace amounts , Impurities such as hydrogen and hydrogen gas are present. This process aims to extract high-purity hydrogen from the purge gas and simultaneously capture it. .

[0059] Step 1: Raw material pretreatment

[0060] First, the ammonia synthesis off-gas is introduced into a multi-stage compressor for pressurization, reaching a pressure of 1.5 MPa to meet the operational requirements of the subsequent membrane separation unit. Then, the gas flows through a molecular sieve dehydration unit, where free moisture is completely removed to prevent corrosion of equipment or catalyst poisoning caused by water vapor at low temperatures or during adsorption, resulting in a dry pretreated gas.

[0061] Step 2: Deep removal of heavy impurities

[0062] The pretreated gas is introduced into the first temperature-switched adsorption tower (TSA-1). This tower is filled with a specialized activated carbon / molecular sieve composite adsorbent, and the operating temperature is set to 100℃. At this temperature, the adsorbent... , , Trace amounts of moisture have a strong affinity for these impurities, which are effectively adsorbed and removed, resulting in purified gas free of acidic gases. To ensure continuous operation of the unit, the system is equipped with three TSA-1 adsorption towers connected in parallel. When one tower is in adsorption mode, the other two are in depressurization and heating regeneration modes, respectively. The regeneration process utilizes the heat generated by the combustion of fuel gas from subsequent processes to raise the temperature inside the tower to 200°C, causing the adsorbed impurities to desorb. The regenerated gas is then cooled and sent to subsequent processing steps.

[0063] Step 3: Remove light hydrocarbons and nitrogen

[0064] The purified gas, after being stripped of heavy impurities, then enters the second temperature-switched adsorption tower (TSA-2). The operating temperature of this tower is also set at 100℃, primarily for... , and some Adsorption occurs. Since these components have a certain adsorption capacity on specific adsorbents, most of them can be adsorbed by controlling temperature and pressure. and Intercepted, output and The main component is crude hydrogen intermediate gas. The TSA-2 system also adopts a two-tower or multi-tower alternating operation mode, and its regeneration process is similar to that of TSA-1, with the regenerated desorbed gas being drawn out of the system.

[0065] Step 4: Membrane pre-separation

[0066] The crude hydrogen intermediate gas is pressurized to 2.0 MPa and then introduced into the membrane separation unit. This unit uses a polyimide hollow fiber membrane module, utilizing... and , , Physical separation is achieved by addressing the significant differences in the permeation rates of gases within the membrane material. Under pressure-driven conditions... Molecules rapidly permeate through the membrane wall, forming a permeate-side gas (hydrogen-rich flow), while the retentate-side gas is enriched with most of the hydrogen. , , And all of them .

[0067] Step 5: Pressure Swing Adsorption Refining

[0068] The permeate-side gas (hydrogen-rich stream) is further compressed to 3.0 MPa and then fed into a pressure swing adsorption (PSA) tower assembly. This assembly adsorbs residual trace amounts of gas under high pressure. , and Unadsorbed As a product gas output, its purity meets the high-purity hydrogen standard after analysis and testing. During the decompression phase of adsorption bed switching, a portion rich in hydrogen will be released. The gas in question is collected separately and then fed into subsequent processes. Capture system.

[0069] Step Six: Carbon Dioxide Capture and Conversion

[0070] The gas trapped on the membrane separation unit, the regeneration desorption gas from TSA-1 and TSA-2, and the PSA stripping gas are all collected and introduced into the catalytic conversion reactor. The reactor is packed with a copper-based catalyst, and under conditions of 280℃ and 0.8 MPa, catalytic conversion occurs. Transformation reaction ( + → + ), will the remaining Almost completely transformed The reacted gas mixture is cooled to room temperature by a heat exchanger, and then processed by a cryogenic liquefaction unit to separate a liquid with a purity of over 99.9%. The product is transported to the storage tank; the remaining uncondensed gas (mainly containing...) , , It has a high calorific value and is used as fuel gas in factory boilers for recycling.

[0071] Example 2: Process for Resource Utilization of Refinery Dry Gas

[0072] This example focuses on processing reformer dry gas or hydrocracking dry gas from an oil refinery. These feedstock gases are characterized by low olefin content but high sulfur content, and contain a certain amount of... The goal is to produce fuel cell-grade hydrogen and reduce carbon emissions, along with hydrocarbons.

[0073] Step 1: Raw material pretreatment

[0074] The refinery dry gas is first compressed to 2.0 MPa by a screw compressor. Given that the refinery gas may contain unsaturated hydrocarbons, a hydrogenation reactor is installed before it enters the drying tower to saturate it. The gas then passes through an alumina dehydration bed, with the dew point strictly controlled, to obtain pretreated gas.

[0075] Step 2: Deep removal of heavy impurities

[0076] The pretreated gas enters the first temperature-switched adsorption tower (TSA-1). Considering the high content of sulfides and nitrogen oxides in the refinery gas, the operating temperature for this step is set at 120°C to enhance the adsorption capacity. The adsorption capacity of NH3 is considered. After the gas passes through the bed, sulfides and nitrogen oxides are completely removed. During the regeneration stage, an electric heater is used to raise the bed temperature to 220°C to desorb pollutants. To cope with fluctuations in refinery gas conditions, TSA-1 adopts a dual-tower parallel design to ensure stable operation even when handling sudden high concentrations of impurities.

[0077] Step 3: Remove light hydrocarbons and nitrogen

[0078] The purified gas then enters the second temperature-switched adsorption tower (TSA-2). The focus here is on removing ethane, ethylene, and some methane, which are characteristic of refinery gas. The operating temperature is maintained at 110°C, and by precisely controlling the adsorption time, H2 and CO2 are retained to the maximum extent, while only CH4 and some N2 are adsorbed, thereby obtaining a crude hydrogen intermediate gas rich in H2 and CO2.

[0079] Step 4: Membrane pre-separation

[0080] The crude hydrogen intermediate gas enters the polysulfone hollow fiber membrane separation unit. Since the refinery dry gas has a relatively high CO2 content, membrane separation not only separates H2 but also preliminarily enriches CO2. The operating pressure is controlled at 2.5 MPa, resulting in relatively pure H2 on the permeate side and a high-concentration CO2 mixture on the retrieval side.

[0081] Step 5: Pressure Swing Adsorption Refining

[0082] The permeate-side gas enters the pressure swing adsorption (PSA) tower assembly. To obtain extremely high purity hydrogen (e.g., 99.999%), the PSA system is operated at a pressure of 3.5 MPa and the adsorption time is set to 5 minutes. This step effectively removes residual N2 and trace amounts of CH4. Notably, the gas released from the PSA contains a significant amount of CO2; this portion is directly piped into the CO2 recovery line, avoiding the waste of valuable components.

[0083] Step Six: Carbon Dioxide Capture and Conversion

[0084] The combined gas mixture, containing all CO2-containing gas streams, enters the catalytic conversion reactor. Although the CO content in the refinery dry gas is low, a copper-based catalyst is still installed to completely eliminate CO and further increase CO2 production. The reaction conditions are set at 250°C and atmospheric pressure. After the reaction, the gas mixture is compressed and cooled. Due to the high partial pressure of CO2 in the mixture, liquefaction and separation become easier, ultimately producing food-grade or industrial-grade liquid CO2 with a purity of not less than 99.9%. The purified tail gas still has a considerable calorific value and is returned to the refinery's fuel network.

[0085] Example 3: Comprehensive Utilization Process of Chlor-alkali Tail Gas

[0086] This example deals with the tail gas generated during the electrolysis process in the chlor-alkali industry (commonly known as "saltwater tail gas" or "air released from the hydrogen main pipe"). Its characteristics are that the gas volume is relatively small but the purity fluctuates greatly, and it contains trace amounts of HCl and O2 produced by the hydrolysis of chlorine.

[0087] Step 1: Raw material pretreatment

[0088] The chlor-alkali tail gas is first washed with water in a scrubbing tower to remove any trace amounts of chlorine, and then compressed to 1.2 MPa. Because the chlor-alkali process is sensitive to moisture, a high-efficiency silica gel dryer is used in the drying step to ensure extremely low moisture content in the outlet gas, resulting in pretreated gas.

[0089] Step 2: Deep removal of heavy impurities

[0090] The pretreated gas enters the first temperature-switched adsorption tower (TSA-1). Given that the chlor-alkali tail gas may have come into contact with an ammonia-containing medium and contains HCl hydrolysis products, the operating temperature for this step is set at 90℃, specifically for adsorbing HCl, NH3, and moisture. The adsorbent selection focuses on acid resistance and high capacity. The regeneration process is carried out at 190℃, and the resulting acidic waste gas is neutralized before being discharged. The system is equipped with two TSA-1 adsorption towers, enabling seamless switching.

[0091] Step 3: Remove light hydrocarbons and nitrogen

[0092] The purified gas, after being decontaminated, enters the second temperature-switched adsorption tower (TSA-2). Chlor-alkali tail gas itself contains relatively few hydrocarbon impurities; this step primarily aims to remove O2 and N2 from the air (if the tail gas is collected in an open environment). The operating temperature is set at 130℃, utilizing the selective adsorption of O2 by the adsorbent to improve hydrogen recovery. The regeneration temperature is 230℃.

[0093] Step 4: Membrane pre-separation

[0094] The crude hydrogen intermediate gas is introduced into the membrane separation unit. Considering the small flow rate of the chlor-alkali tail gas, a compact polyimide membrane module was selected. The operating pressure is maintained at 1.8 MPa. Since the CO2 content in the tail gas is extremely low, the main function of membrane separation is to further purify H2 and remove residual N2 / O2. The amount of gas on the retaining side is very small, mainly non-condensable gas.

[0095] Step 5: Pressure Swing Adsorption Refining

[0096] The permeate gas enters the pressure swing adsorption (PSA) tower assembly. To obtain a stable supply of high-purity hydrogen at a relatively small throughput (meeting the needs of the electronics industry), the PSA operating pressure is increased to 4.0 MPa, and the adsorption time is shortened to 3 minutes to increase the frequency. The desorbed gas contains trace amounts of H2 and impurities, and is entirely incorporated into the CO2 recovery process.

[0097] Step Six: Carbon Dioxide Capture and Conversion

[0098] Since the raw gas itself has an extremely low CO2 content, the main task of step six becomes tail gas treatment. The collected mixed gas undergoes an oxidation reaction in a catalytic conversion reactor (if there is residual organic matter or CO), with the copper-based catalyst operating at 320°C. After the gas is cooled, the water vapor is condensed and separated, and the remaining small amount of CO2 and non-condensable gas are used as low-calorific-value fuel gas to supply the plant's heating boilers, achieving true near-zero emissions.

[0099] Example 4: Low-carbon treatment process for propane dehydrogenation tail gas

[0100] This example applies to byproduct hydrogen produced in a propane dehydrogenation (PDH) unit. The feed gas is rich in H2, but also contains a large amount of unreacted C3H6 and C3H8, as well as CH4 and C2H6 produced from propane cracking, along with green oil (heavy hydrocarbons) and trace amounts of sulfides.

[0101] Step 1: Raw material pretreatment

[0102] The PDH tail gas is first compressed to 3.0 MPa. Because the gas contains easily polymerizable olefins, polymerization inhibitor injection points and a protective bed must be installed before it enters the drying tower to prevent blockage of downstream equipment. It then undergoes deep dehydration to obtain pretreated gas.

[0103] Step 2: Deep removal of heavy impurities

[0104] The pretreated gas enters the first temperature-switched adsorption tower (TSA-1). Sulfides in the PDH tail gas mainly exist in the form of organic sulfur, and the operating temperature is set at 140°C to ensure deep removal of organic sulfur. In addition, this tower also adsorbs recombinant and decomposed fragments carried by the gas stream. The regeneration temperature reaches up to 240°C to thoroughly remove carbon deposits and heavy organic matter. The system employs a three-tower process to handle complex impurity compositions.

[0105] Step 3: Remove light hydrocarbons and nitrogen

[0106] The purified gas enters the second temperature-switched adsorption tower (TSA-2). This is one of the key steps in the entire process, aiming to remove C3 hydrocarbons and CH4 to the greatest extent possible before PSA. The operating temperature is set at 150°C, utilizing the strong adsorption capacity of the adsorbent for these large molecular hydrocarbons, allowing only H2 and CO2 to pass through. The regeneration process is carried out at 220°C, and the hydrocarbon gases desorbed during regeneration have a high calorific value.

[0107] Step 4: Membrane pre-separation

[0108] The crude hydrogen intermediate gas enters the membrane separation unit. Since the hydrocarbon content in the gas is still relatively high, membrane separation plays a crucial role in bridging the upstream and downstream processes. The polyimide membrane preferentially permeates H2 under high pressure (3.0 MPa), while the retrieval side is enriched with large amounts of propane, propylene, and methane. This not only protects the subsequent PSA catalyst but also provides a high-concentration feedstock for CO2 capture.

[0109] Step 5: Pressure Swing Adsorption Refining

[0110] The permeate gas (with significant hydrocarbon removal) enters the pressure swing adsorption (PSA) tower assembly. The operating pressure is 2.5 MPa, and the adsorption time is set to 8 minutes. At this point, the primary task of the PSA is to remove residual N2 and CH4, producing high-purity polymer-grade or refinery-grade hydrogen. The desorbed gas, rich in CH4 and containing a small amount of H2, is collected.

[0111] Step Six: Carbon Dioxide Capture and Conversion

[0112] The gas from the membrane retrieval side, TSA regeneration gas, and PSA stripping gas are combined. Since the feed gas contains virtually no CO, the core of step six is ​​to use a catalytic converter to treat trace amounts of oxygen and olefins in the retrieval side gas, preventing the risk of explosion during subsequent liquefaction. The reaction is carried out at 200°C and 0.5 MPa. The resulting gas mixture undergoes cryogenic separation. Due to the presence of a large amount of C3 hydrocarbons, LPG products can be separated first. The CO2 in the remaining gas (from the feed gas) is further concentrated and liquefied, ultimately yielding high-purity liquid CO2, achieving full-component resource utilization of the PDH unit's tail gas.

[0113] Example 5: Multi-source mixed gas synergistic treatment process

[0114] This example simulates an industrial park that mixes synthetic ammonia off-gas, refinery dry gas, and chlor-alkali tail gas from different plants to balance gas source fluctuations and optimize overall economic benefits.

[0115] Step 1: Raw material pretreatment

[0116] The three raw materials are compressed and dehydrated separately by independent systems to raise the pressure to 1.0 MPa and remove the characteristic moisture carried by each. After being combined, they form a relatively stable mixed pretreated gas.

[0117] Step 2: Deep removal of heavy impurities

[0118] The mixed gas enters the first temperature-switched adsorption tower (TSA-1). Since the mixed gas contains H2S from refinery gas, trace amounts of acid from chlor-alkali gas, and NH3 from synthetic ammonia gas, the operating temperature of TSA-1 is set to 80℃ (to account for the adsorption characteristics of different impurities), and the contact time is appropriately extended. This tower can effectively handle this complex mixture of gases. The regeneration process is carried out at 180℃, and the system employs a four-tower linkage to ensure sufficient processing capacity during gas source switching.

[0119] Step 3: Remove light hydrocarbons and nitrogen

[0120] The purified gas enters the second temperature-switched adsorption tower (TSA-2). The hydrocarbon content in the mixed gas is moderate, and the operating temperature is set at 150℃ to maximize the removal rates of CH4 and CO. TSA-2 also employs multiple towers in parallel to ensure long-term operation.

[0121] Step 4: Membrane pre-separation

[0122] The crude hydrogen intermediate gas enters the membrane separation unit. The operating pressure is set to 1.0 MPa (lower limit, because some gas source pressures are low). The polysulfone membrane exhibits significant separation performance for H2 / N2 / CH4, maintaining good permeation flux even at this pressure. Crude hydrogen is obtained on the permeate side, while CO2-rich tail gas is obtained on the retrieval side.

[0123] Step 5: Pressure Swing Adsorption Refining

[0124] The permeate-side gas enters the pressure swing adsorption (PSA) tower assembly. To accommodate potential fluctuations in impurities in the mixed gas, the PSA operating pressure is set to 1.5 MPa (a lower value to increase safety margin), and the adsorption time is set to 10 minutes (a longer value to ensure deep purification). The high-purity hydrogen produced in this step is of stable quality. The CO2-rich gas extracted from the PSA is deliberately extracted and not mixed with other regeneration gases; instead, it is metered separately and enters the CO2 system for accurate calculation of carbon capture.

[0125] Step Six: Carbon Dioxide Capture and Conversion

[0126] The gas from the membrane retrieval side, the TSA regeneration desorption gas, and the PSA stripping gas are all introduced into the catalytic conversion reactor. Due to the complex composition of the mixed gas, containing CO from different sources, the copper-based catalyst operates under relatively high conditions of 350℃ and 1.0 MPa to ensure that all CO is converted into CO2. The mixed gas after reaction is cooled and liquefied, successfully separating liquid CO2 with a purity of not less than 99.9%. The uncondensed tail gas, after calorific value calculation, is rationally allocated to different boilers within the park as fuel, achieving the dual goals of energy cascade utilization and carbon emission reduction.

[0127] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An integrated treatment method for purifying hydrogen-containing industrial waste gas and recovering carbon resources, characterized in that, Includes the following steps: (1) Containing , The industrial by-product hydrogen feed gas containing impurities is compressed and dehydrated to obtain pretreated gas. (2) The pretreated gas is introduced into the first temperature-switching adsorption tower, and adsorption is performed to remove the gas under the set temperature conditions. , , After removing moisture, the gas is purified by removing heavy impurities; (3) The purified gas, after being de-impure, is passed into a second temperature-switching adsorption tower, where it is adsorbed and removed from the gas under set temperature conditions. , and some This yields crude hydrogen intermediate gas; (4) The crude hydrogen intermediate gas is introduced into the membrane separation unit, and the difference in gas permeation rate is used to separate the hydrogen-rich intermediate gas into a membrane separation product. Permeable side gas and rich in and the gas trapped on the side containing residual impurities; (5) The rich The permeate-side gas is fed into the pressure swing adsorption tower group, and residual trace impurities are adsorbed through periodic pressure changes, ultimately yielding high-purity product hydrogen. (6) The gas trapped on the side is combined with the regenerated desorbed gas from the first and second temperature-switching adsorption towers and then introduced into the catalytic conversion reactor. Under the action of the catalyst, the residual gas is converted into a gas. Transform into The reacted gas mixture was then cooled and liquefied, separating the liquid phase. The product recovers and reuses uncondensed gas as fuel gas.

2. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (2), the operating temperature of the first variable temperature adsorption tower is 80-150℃, and the regeneration temperature is 180-250℃.

3. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (3), the operating temperature of the second variable temperature adsorption tower is 80-150℃, and the regeneration temperature is 180-250℃.

4. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (4), the membrane material used in the membrane separation unit is polyimide or polysulfone hollow fiber membrane, and the operating pressure is 1.0-3.0 MPa.

5. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (5), the operating pressure of the pressure swing adsorption tower group is 1.5-4.0 MPa, and the adsorption time is 2-10 minutes.

6. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (6), the catalytic conversion reactor is filled with a copper-based catalyst, the reaction temperature is 200-350℃, and the reaction pressure is atmospheric pressure to 1.0MPa.

7. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (6), the liquid The purity of the product is no less than 99.9%.

8. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In steps (2) and (3), both the first and second temperature-switching adsorption towers employ at least two adsorption towers connected in parallel to achieve continuous operation.

9. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: In step (5), the oil rich in... The gas is also introduced into step (6) for further processing. Capture.

10. The integrated treatment method for purifying hydrogen-containing industrial tail gas and recovering carbon resources according to claim 1, characterized in that: The industrial by-product hydrogen feed gas is selected from one or more of the following: synthetic ammonia off-gas, refinery dry gas, chlor-alkali tail gas, and propane dehydrogenation tail gas.

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