Method for producing hydrogen enrichment products and recovering CO2 in a hydrogen production process unit

Abstract

A process and apparatus for producing a hydrogen-enriched product from an effluent stream from a hydrogen production process unit and capturing CO2 is described. The process utilizes a PSA system that produces at least two product streams and a CO2 capture system integrated to capture additional hydrogen and CO2 from the tail gas stream of a hydrogen PSA unit in the hydrogen production process.

Description

Technical Field

[0001] (Description of Priority) This application claims the benefit of U.S. Provisional Application No. 63 / 167,338, filed on March 29, 2021, entitled "Method of Producing Hydrogen and Recovering CO2 in a Hydrogen Production Process Unit", which is hereby incorporated by reference in its entirety.

Background Art

[0002] Hydrogen is expected to have significant growth potential as a clean combustion fuel. However, hydrogen production has traditionally been a significant source of CO2 emissions, and government regulations and social pressures have increased the taxation or penalties on CO2 emissions, or incentives on the incentives for CO2 capture. As a result, there is a major competition to reduce hydrogen production costs while recovering the by-product CO2 for subsequent underground storage in order to capture growing markets. CO2 can be separated as steam fed into a common pipeline, but it is more likely to be produced in a liquefied form for easy transportation by truck or ship due to the current lack of CO2 pipeline infrastructure in certain regions of the world.

[0003] The desired level of reduced CO2 emissions depends on the economic state of the region, and some hydrogen producers prioritize maximizing hydrogen production with CO2 capture, others prioritize minimizing CO2 emissions from hydrogen production, and some fall somewhere in between. Another important factor is the reformer technology selected for a given hydrogen production unit. In a steam reforming plant, 50% - 60% CO2 capture may be sufficient, but in an autothermal reformer (ATR), a gasifier, or a partial oxidation (POX) reformer, over 90% or over 95% may be expected.

[0004] Most existing hydrogen production processes utilize pressure swing adsorption (PSA) to recover high-purity product hydrogen from shift synthesis gas. The low-pressure exhaust gas flow from the PSA unit is typically combusted to generate heat or steam for the process. If the flow is not sent to a combustor, purging is required to prevent the accumulation of impurities in the process.

[0005] U.S. Patent No. 8,021,464 describes a process for the combined production of hydrogen and CO2 from a mixture of hydrocarbons to be converted into synthesis gas. The synthesis gas is separated into a hydrogen-enriched flow and a PSA off-gas flow in a PSA unit. The PSA off-gas is compressed and dried, followed by several sequential steps of condensing and separating a CO2-rich condensate, with the temperature decreasing at each step, ranging from ambient temperature to -56°C. However, the process results in a purge flow containing a significant amount of CO2 that must be removed from the process. Permeation modules can be used to improve separation, but at the cost of increased power requirements.

[0006] U.S. Patent No. 8,241,400 describes a process for recovering hydrogen and CO2 from a hydrocarbon mixture using a system comprising a reformer unit, an optional water-gas shift reactor, a PSA unit, and a cryogenic purification unit or catalytic oxidation device. The PSA unit generates three flows: a high-pressure hydrogen flow, a low-pressure CO2 flow, and a CH4-rich flow which is removed during a CO2 co-purge step. Purified CO2 from the CO2 purification unit in the process is used as a co-purge in the PSA unit. The adsorption step is performed at a pressure of 250 psig to 700 psig. The pressure during the co-purge step is in the range of 300 psig to 800 psig, and the CO2 co-purge flow is introduced at a pressure higher than that during the adsorption step.

[0007] The use of a second high-pressure feed flow (CO2 co-purge flow) increases the cost and complexity of the process under U.S. Patent No. 8,241,400. The need for segmented adsorbents (or two separate vessels) and isolation valves between them and the intermediate side draw further increases the cost and complexity of the process.

[0008] Therefore, an improved hydrogen production process with improved cost-effective CO2 capture is needed. [Brief explanation of the drawing]

[0009] [Figure 1] This figure illustrates one embodiment of a method for producing hydrogen from a steam reforming process unit and recovering CO2 using a PSA system that generates at least two product flows according to the present invention. [Figure 2] This is a diagram of one embodiment of a three-product PSA unit for use in a PSA system that generates at least two product flows according to the present invention. [Figure 3] This is a diagram of another embodiment of a method for producing hydrogen from a steam reforming process unit and recovering CO2 using another embodiment of a PSA system that generates at least two product flows of the present invention. [Figure 4] This figure shows another embodiment of a method for producing hydrogen from an ATR process unit and recovering CO2 using a PSA system that generates at least two product streams according to the present invention. [Figure 5] This figure shows another embodiment of a method for producing hydrogen from an ATR process unit and recovering CO2 using a PSA system that generates at least two product streams according to the present invention. [Figure 6] This is a diagram of one embodiment of a CO2 recovery system using a binary refrigerant CO2 fractionation process. [Figure 7] This is a diagram of another embodiment of a CO2 recovery system using a mixed refrigerant CO2 fractionation process. [Modes for carrying out the invention]

[0010] The process enables the production of hydrogen enrichment products and CO2 recovery from the effluent logistics of a hydrogen production process unit. The process uses a PSA system that generates at least two product streams to recover hydrogen enrichment products from the exhaust gas flow from a hydrogen separation unit in the hydrogen production process. The process utilizes a CO2 recovery system integrated with the PSA that generates at least two product streams to recover additional hydrogen and high-purity liquid CO2.

[0011] Extracting hydrogen enrichment products (and in some embodiments, pure hydrogen products) directly from the top flow of a CO2 recovery system using a PSA system that generates at least two product flows can offer economic advantages over systems using a recirculation configuration. Additional hydrogen production substantially improves process economics. By using a PSA system that generates at least two product flows in the top flow of the CO2 recovery system, non-permeable CO2 losses resulting from the use of membrane separation processes are also avoided. Utilizing a PSA system that generates at least two product flows brings innovation and flexibility, reduces downstream equipment size and utility, and increases captured CO2 (because the impurity-rich purge flow does not contain significant CO2).

[0012] The hydrogen production process unit may include a novel or existing steam reforming unit with an optional gas-heated reformer, a self-thermal reforming unit with an optional gas-heated reformer, a gasification unit, or a partial oxidation (POX) unit. The hydrogen production process produces an effluent containing hydrogen, carbon dioxide, water, and a mixture of gases including at least one of methane, carbon monoxide, nitrogen, and argon.

[0013] The spillway is first sent to a hydrogen pressure swing adsorption (PSA) unit, where it is separated into a hydrogen-rich high-pressure hydrogen stream and a hydrogen-depleted flue gas stream containing the remaining hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon. The high-pressure hydrogen stream contains 90% of the hydrogen in the spillway and is recovered.

[0014] The hydrogen-depleted exhaust gas flow is compressed and sent to a CO2 capture system, where it is separated into a liquid CO2 product and a top flow containing hydrogen and some carbon dioxide, as well as some of at least one of methane, carbon monoxide, nitrogen, and argon.

[0015] The top flow is sent to a PSA system that generates at least two product flows. The PSA system, which generates at least two product flows, separates the top flow into at least two flows: a second high-pressure hydrogen flow and a low-pressure CO2 flow. The high-pressure hydrogen flow is rich in hydrogen. The low-pressure CO2 flow is rich in carbon dioxide. The second high-pressure hydrogen flow is recovered, and the low-pressure CO2 flow is recycled to the compressor.

[0016] In some embodiments, the process enables the recovery of 80–90% of the hydrogen in the exhaust gas stream from the hydrogen PSA unit, as well as the capture of substantially all (e.g., 95–100%) of the CO2.

[0017] The effluent from the hydrogen production process unit supplied to the hydrogen PSA system is typically in the range of 20°C to 60°C, 30°C to 50°C, or 40°C (or any combination of temperature ranges). The pressure is typically in the range of 2,000 to 5,000 kPa.

[0018] The effluent is separated into a high-pressure hydrogen stream and an exhaust gas stream in the hydrogen PSA unit. The high-pressure hydrogen stream contains 80% to 90% of the hydrogen in the effluent. The high-pressure hydrogen stream is typically in the pressure range of 2,000 to 5,000 kPa.

[0019] The exhaust gas stream from a hydrogen PSA unit containing 10% to 20% hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon in the effluent stream is at a pressure in the range of 100 to 200 kPa.

[0020] The exhaust gas stream is compressed to a pressure in the range of 3,000 to 6,000 kPa and sent to a CO2 recovery system. The compressed exhaust gas stream is dried and cooled to a temperature in the range of -20°C to -50°C. This is separated into a CO2-enriched stream and a top stream containing some hydrogen, some carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon. In some embodiments, the CO2-enriched stream contains substantially all (e.g., 95% to 100%) of the CO2 in the exhaust gas stream from the hydrogen PSA unit and substantially no hydrogen, methane, carbon monoxide, nitrogen, and argon. In some embodiments, the CO2-enriched stream contains 95.0 mol% or more of CO2, 98.0 mol% or more of CO2, or 98.5 mol% or more of CO2, or 99.0 mol% or more of CO2, or 99.5 mol% or more of CO2, or 99.9 mol% or more of CO2.

[0021] The CO2 recovery system can include a distillation column, the CO2-enriched product stream is recovered from the bottom of the column, and the lighter components (such as hydrogen, methane, nitrogen, etc.) are recovered from the top of the column. The CO2 recovery system can alternatively or similarly include one or more continuous flash gas-liquid separation vessels, each separator providing additional theoretical stages of mass transfer, the CO2-enriched product is recovered in the liquid stream, and the lighter components (such as hydrogen, methane, nitrogen, etc.) are recovered in the top vapor stream.

[0022] The CO2-enriched stream is recovered. The CO2-enriched stream may be a liquid stream. In some cases, if necessary, the liquid stream may be vaporized and used.

[0023] The overhead stream is sent to a PSA system that produces at least two product streams. The PSA system that produces at least two product streams may be a three-product PSA unit having three product streams, a PSA unit having two product streams, or two PSA units each having two product streams, where the product stream from the first PSA unit is supplied to the second PSA unit.

[0024] The three-product PSA unit includes four or more PSA adsorption vessels. Generally, there are at least six vessels, typically 8 to 14 vessels. The vessels include one or more, generally 1 to 5, typically 2 to 3 adsorbent layers. The proportion of the adsorbent layer bed is typically 10% to 100%. Different adsorbent layers have different selectivities for the components in the overhead stream, as known to those skilled in the art. Some layers contain adsorbents for selectively adsorbing CO2 with respect to methane, carbon monoxide, nitrogen, argon, and hydrogen, and include, but are not limited to, layers of activated alumina, silica gel, and sodium Y zeolite. Other layers contain adsorbents for selectively adsorbing CO2, methane, carbon monoxide, nitrogen, and argon with respect to hydrogen, and include, but are not limited to, layers of activated carbon, silica gel, and molecular sieve zeolite (e.g., 5A or sodium X zeolite). Those skilled in the art understand that other zeolites can be used and recognize the method of selecting appropriate adsorbents.

[0025] There is a first opening at one end of the vessel and a second opening at the opposite end. For convenience, the ends are referred to as the upper and lower parts of the vessel. The first opening at the bottom is selectively connected to a high-pressure feed gas inlet line and a low-pressure exhaust gas outlet line. The second opening at the top of the vessel is selectively connected to a high-pressure product outlet line, a medium-pressure vent gas outlet line, and a low-pressure purge gas inlet line.

[0026] The supply gas enters at high pressure through a first opening at the bottom of the vessel, and a high-pressure co-current adsorption and product removal step is performed, after which the product exits the vessel at high pressure through a second opening at the top of the vessel. There is at least one co-current depressurization step, followed by a medium-pressure co-current depressurization and vent gas removal step. The second flow is removed at a second pressure through an opening at the top of the vessel. There are countercurrent blowdown and countercurrent purge steps. The purge gas enters at low pressure through an opening at the top of the vessel. CO2 can be removed at low pressure through an opening at the bottom of the vessel during either or both of the countercurrent blowdown and countercurrent purge steps. There is at least one countercurrent repressurization step after the countercurrent purge and exhaust gas removal step.

[0027] A PSA system that generates at least two product flows may include one PSA unit having two product flows, or two PSA units in series, each having two product flows. In a single PSA unit having two product flows, the top flow from the CO2 capture system is introduced into the PSA unit, where it is separated into a low-pressure exhaust gas flow rich in CO2 and a high-pressure flow rich in hydrogen (e.g., 85% to 95%). The high-pressure flow may contain a portion of at least one of methane, carbon monoxide, nitrogen, and argon.

[0028] Using two series-connected PSA units, the top flow from the CO2 capture system is introduced into a first PSA unit having two product flows, where it is separated into a low-pressure flue gas flow rich in CO2 and a high-pressure flow containing substantially all hydrogen (e.g., 85%–95%), as well as a portion of at least one of methane, carbon monoxide, nitrogen, and argon. The high-pressure flow is fed into a second PSA unit having two product flows, where it is separated into a high-pressure hydrogen flow rich in hydrogen and a low-pressure flow containing substantially all methane, carbon monoxide, nitrogen, and argon (e.g., 95%–100%).

[0029] The PSA system of the present invention that produces at least two product flows offers several advantages. The second flow is not removed at high pressure. In a three-product PSA unit, the second flow is between the high pressure at which hydrogen is removed and the low pressure at which CO2 is removed, but is removed at an intermediate pressure much closer to the low pressure than the high pressure. The intermediate pressure is typically less than 450 kPa. If the PSA system that produces at least two product flows includes two PSA units, the second flow is removed at a low pressure, typically less than 250 kPa.

[0030] Furthermore, a high-pressure co-purge flow is not used. Additionally, the vessel is not segmented. The second flow is withdrawn through an opening at the top of the vessel. Therefore, an isolation valve and side-draw outlet are not required between the two adsorbent beds. These factors make the 3-product PSA unit far less complex and less expensive to construct and operate than the PSA and process described in U.S. Patent No. 8,241,400.

[0031] The temperature of the top flow entering the PSA system, which generates at least two product flows (after chilling recovery and heat exchange), is typically within the range of 20°C to 60°C, 30°C to 50°C, or 40°C (or any combination of these temperature ranges).

[0032] The hydrogen concentration in the top flow supplied to a PSA unit with at least two product flows is generally in the range of 20 mol% to 60 mol%. For example, the hydrogen concentration in the top gas within a CO2 recovery system for steam methane reforming plant exhaust gas is 30 mol% to 50 mol%.

[0033] In the case of a 3-product PSA unit, 80% to 90% of the hydrogen in the top flow is typically recovered in the high-pressure hydrogen stream, which is substantially free of CO2, methane, carbon monoxide, nitrogen, and argon. The high-pressure hydrogen stream typically contains less than 1%, less than 0.1%, or less than 0.01% of CO2 relative to the top flow. The high-pressure hydrogen stream typically contains less than 10%, less than 5%, less than 2%, less than 1%, or less than 0.1% of methane, carbon monoxide, nitrogen, and argon relative to the top flow. The high-pressure hydrogen stream is typically removed at high pressures ranging from 1,000 to 6,000 kPa, or 2,000 to 5,000 kPa, or 2,500 to 4,500 kPa.

[0034] Low-pressure exhaust gas flows are typically removed at low pressures in the range of 50 kPa to 250 kPa, or 100 kPa to 200 kPa.

[0035] The low-pressure CO2 stream typically contains substantially all (e.g., 95%–100%) of the CO2 in the top flow. This typically contains 10% hydrogen (e.g., 5%–15%) relative to the top flow, and 40% methane, carbon monoxide, nitrogen, and argon (e.g., 20%–60%) relative to the top flow.

[0036] If a PSA system that produces at least two product flows contains three product PSA units, the second gas flow is removed at an intermediate pressure between high and low pressure, where the intermediate pressure is much closer to low pressure than high pressure, typically within 400 kPa, 300 kPa, or 200 kPa of low pressure. Typically, the intermediate pressure product flow is removed at pressures in the range of 150 kPa to 450 kPa, or 250 kPa to 350 kPa. There is some overlap between the intermediate and low pressure ranges, but in certain cases, low pressure is understood to be lower than intermediate pressure.

[0037] The second flow typically contains 40% to 80% of the methane, carbon monoxide, nitrogen, and argon in the top flow. The second flow typically contains 10% hydrogen (e.g., 5% to 25%) relative to the top flow, and less than 5%, less than 1%, or less than 0.1% CO2 relative to the top flow.

[0038] All or part of the second flow can be recycled to a hydrogen production process unit, a water-gas shift process unit, and / or a combustion unit.

[0039] If a PSA system that produces at least two product flows includes one PSA unit, the top flow is introduced into the PSA unit, where it is separated into a low-pressure CO2 flow containing substantially all (95%–100%) of CO2 and a high-pressure flow containing substantially all (e.g., more than 75%, or 85%–95%) of hydrogen, as well as a portion (50%–90%) of at least one of methane, carbon monoxide, nitrogen, and argon. The low-pressure CO2 flow has a low pressure of 50 kPa–250 kPa, or 100 kPa–200 kPa. The high-pressure flow has a high pressure in the range of 1,000–6,000 kPa, or 2,000 kPa–5,000 kPa, or 2,500 kPa–4,500 kPa.

[0040] If a PSA system that generates at least two product flows includes two PSA units in series, the high-pressure flow from the first PSA unit is supplied to the second PSA unit, where it is separated into a high-pressure hydrogen flow containing substantially all hydrogen (e.g., 80%–90%) and a second gas flow. The second gas flow contains substantially all (e.g., 95%–100%) of at least one of methane, carbon monoxide, nitrogen, and argon. The high-pressure hydrogen flow typically has a high pressure in the range of 1,000–6,000 kPa, or 2,000–5,000 kPa, or 2,500–4,500 kPa. In this configuration, the second flow has a pressure in the range of 50 kPa–250 kPa, or 100 kPa–200 kPa.

[0041] The first PSA unit contains an adsorbent for selectively adsorbing CO2 from methane, carbon monoxide, nitrogen, argon, and hydrogen, and includes, but is not limited to, layers of activated alumina, silica gel, and sodium Y zeolite. The second PSA unit contains an adsorbent for selectively adsorbing CO2, methane, carbon monoxide, nitrogen, and argon from hydrogen, and includes, but is not limited to, layers of activated carbon, silica gel, and molecular sieve zeolite (e.g., 5A or sodium X zeolite). Those skilled in the art will understand that other zeolites may be used and will know how to select appropriate adsorbents for the first and second PSA units.

[0042] If a PSA system that generates at least two product streams includes a three-product PSA unit, the high-pressure hydrogen stream may be removed during the high-pressure co-current adsorption step in the PSA cycle, the second gas stream may be removed during the co-current depressurization step in the PSA cycle, and the low-pressure CO2 stream may be removed during the countercurrent depressurization step and countercurrent purge step in the PSA cycle.

[0043] In some embodiments, if the PSA system that generates at least two product flows is a three-product PSA unit, the PSA cycle is: High-pressure co-current adsorption and hydrogen removal step, A high-pressure co-current adsorption step and a hydrogen removal step followed by at least one co-current depressurization step, A co-flow decompression step followed by at least one co-flow decompression step and a second gas removal step, A counterflow blowdown step and a CO2 removal step are performed, following a medium-pressure parallel flow depressurization and a second gas removal step. Counterflow blowdown step followed by counterflow purge and CO2 removal step, A countercurrent purging and CO2 removal step followed by at least one countercurrent repressurization step, and The process may optionally include at least one countercurrent repressurization step followed by a parallel feed repressurization step, or at least one countercurrent repressurization step followed by countercurrent product repressurization.

[0044] In some embodiments, the CO2 recovery system includes a refrigeration CO2 fractional distillation process, and the refrigeration is provided by at least two refrigeration circuits, one of which utilizes a portion of the liquid CO2 product recovered from the distillation column, or by a single closed-loop multi-component mixed refrigerant circuit, which is described in more detail below.

[0045] In some embodiments, the process may include a catalytic oxidation (CATOX) reactor on a second flow to recover heat in the form of high-pressure steam from unconverted carbon monoxide and methane, as well as unrecovered hydrogen, from the hydrogen production process. Approximately the same amount of heat or steam is generated as when the second flow is sent to the furnace. However, by sending it to the CATOX reactor unit, CO2 emissions resulting from the combustion of these components in the furnace are avoided, and the proportion of CO2 captured from the process increases. The CATOX reactor unit may be nearly isothermal, with a catalyst on one side of the heat exchanger and boiling water on the other. For example, the CATOX reactor unit may have a water / steam (reactor) temperature of 250°C. The size of the reactor may be relatively small, for example, 100,000 Nm³. 3 6,000 Nm / hour of hydrogen production plant capacity 3 The total gas supply rate per hour (fuel gas + oxygen) may also be used.

[0046] In some embodiments, there is a selective bypass configuration that allows the system to operate in the event of a problem with the compressor, the CO2 recovery system, or the PSA system that generates at least two product flows. In this case, the compressor, the CO2 recovery system, or the PSA system that generates at least two product flows is bypassed, and the exhaust gas flow from the hydrogen PSA unit is sent to the furnace or other location in the hydrogen production process unit. Suitable furnace burners include, but are not limited to, the burner described in U.S. Patent No. 6,875,008, modified to include an inlet for the exhaust gas flow, and the burner described in U.S. Patent Application No. 63 / 167,286, filed concurrently with this application, entitled Active And Passive Combustion Stabilization For Burners For Highly and Rapidly Varying Fuel Gas Compositions, each of which is incorporated in whole by reference.

[0047] Additional energy recovery can be obtained from the effluent of the WGS unit in the process. The effluent from the WGS unit can be heat-exchanged with the process flow to form cooled effluent and preheated process flow. Using a process involving the reversible oligomerization reaction of phosphoric acid, waste heat can be recovered from the cooled effluent to generate steam. Contact between waste heat and phosphoric acid results in oligomerization to diphosphate. As a result of oligomerization, water molecules split and condense, causing cooling of the waste heat. The pressure of the diphosphate flow is increased. The waste heat then evaporates the water absorbed by the diphosphate. This results in deoligomerization and hydrolysis, leading to conversion back to phosphoric acid and the generation of more valuable process heat. The pressure of the phosphoric acid flow is then decreased and the cycle is repeated. A waste heat recovery process using the reversible oligomerization of phosphoric acid is available from Qpinch in Antwerp, Belgium.

[0048] Another aspect of the present invention is an apparatus for producing hydrogen enrichment products from a hydrogen production process unit and recovering CO2. In one embodiment, the apparatus includes a hydrogen production process unit having at least one inlet and at least one outlet, a hydrogen PSA unit having an inlet, a hydrogen outlet and an exhaust gas outlet, the inlet of which is in fluid communication with the outlet of the hydrogen production process unit, a compressor having an inlet and an outlet, the inlet of which is in fluid communication with the hydrogen PSA exhaust gas outlet, a CO2 recovery system having an inlet, a first outlet and a top outlet, the inlet of which is in fluid communication with the outlet of the compressor, and a PSA system having at least one inlet, a high-pressure hydrogen outlet and a low-pressure CO2 outlet, the inlet of which is in fluid communication with the top outlet of the CO2 recovery system and the low-pressure CO2 outlet is in fluid communication with the inlet of the compressor.

[0049] In some embodiments, the apparatus includes a dryer and chiller positioned between a compressor and a CO2 recovery system, a dryer having an inlet and at least one outlet, wherein the inlet of the dryer is in fluid communication with the outlet of the compressor, a chiller having a gas inlet, a gas outlet, a chilling fluid inlet, and a chilling fluid outlet, wherein the gas inlet of the chiller is in fluid communication with the outlet of the dryer, the fluid inlet of the chiller is in fluid communication with a chilling fluid source, and the inlet of the CO2 recovery system is in fluid communication with the gas outlet of the chiller.

[0050] In some embodiments, the PSA system further includes a second gas outlet that is in fluid communication with a combustion unit in a hydrogen production process unit, or the second gas outlet of the PSA system is in fluid communication with the inlet of a catalytic oxidation unit, and the outlet of the catalytic oxidation unit is in fluid communication with the inlet of a compressor.

[0051] In some embodiments, the PSA system includes a first PSA unit having an inlet and first and second outlets, and a second PSA unit having an inlet and first and second outlets, wherein the inlet of the first PSA unit includes the inlet of the PSA system, the first outlet of the first PSA unit includes a low-pressure CO2 outlet, the inlet of the second PSA unit is in fluid communication with the second outlet of the first PSA unit, the first outlet of the second PSA unit includes a high-pressure hydrogen outlet, and the second outlet of the second PSA unit includes a second gas outlet.

[0052] Figure 1 shows one embodiment of a hydrogen production process 100 incorporating a PSA system that generates at least two product streams, including the three-product PSA unit of the present invention. Natural gas 105 and water 110 are sent to the reaction section 112 of a steam reforming process unit 120, and assist fuel gas 114 and air 115 are sent to a furnace 118 for combustion with air in the steam reforming process unit 120. Instead of natural gas, other feed streams containing hydrocarbons, including but not limited to naphtha and liquefied petroleum gas (LPG), can be used. The assist fuel gas is an additional fuel source to provide stability and sufficient heat for the reforming reaction, as the PSA exhaust gas or vent gas does not provide enough heat to drive the process. Suitable assist fuel gases include, but not limited to, natural gas and other fuels mainly containing hydrocarbons, such as refined fuel gas, petrochemical composite fuel gas, vaporized naphtha or vaporized liquefied petroleum gas (LPG), or hydrocarbon-containing fuels, and blends thereof with hydrogen up to crude hydrogen or refined hydrogen.

[0053] The steam reforming and water-gas shift reactions produce an outflow stream 125 containing hydrogen, CO2, water, and at least one of methane, carbon monoxide, and nitrogen. The flue gas stream 130 and steam stream 135 also exit the steam reforming process unit 120.

[0054] The spillway 125 has a temperature of 30°C to 50°C (after heat recovery and cooling in the steam reforming process) and a pressure of 2,000 to 3,000 kPa. The spillway 125 is sent to a hydrogen PSA unit 140, where it is separated into a hydrogen-rich high-purity hydrogen stream 145 and a hydrogen-depleted exhaust gas stream 150 containing some hydrogen, CO2, water, and at least one of methane, carbon monoxide, and nitrogen.

[0055] The exhaust gas flow 150 is sent to the compressor 155, where it is compressed from a pressure in the range of 110 kPa to 200 kPa to a pressure in the range of 3,000 kPa to 6,000 kPa.

[0056] The compressed exhaust gas flow 160 is sent to the CO2 recovery unit 165, where it is dried to remove the water flow 167, cooled to a temperature of -20°C to -50°C, and separated into a bottom flow 170 and a top flow 175. The bottom flow 170, which contains liquid CO2, is recovered.

[0057] The top flow 175 is sent to a PSA system 180 that generates at least two product flows, including a three-product PSA unit 185, where it is separated into three flows. The high-pressure hydrogen flow 190 is recovered. The low-pressure CO2 flow 195 is recycled to the compressor 155. The medium-pressure vent gas flow 200, containing at least one of methane, carbon monoxide, and nitrogen, as well as a small amount of hydrogen (e.g., less than 20%, or 10% to 20%), is sent to the steam reforming process unit 120 as fuel.

[0058] The bypass line 202 directs the exhaust gas flow 150 to the furnace 118 in the steam reforming process unit 120 for combustion. This allows the steam reforming process unit 120 to continue operating without recovering CO2 if a problem occurs with the compressor 155, the CO2 recovery unit 165, or the PSA system 180 that generates at least two product flows.

[0059] Figure 2 shows a PSA unit 5 including a PSA adsorption vessel 10. The PSA adsorption vessel 10 includes three adsorption layers 15, 20, and 25. The PSA adsorption vessel 10 includes a first opening 30 at a first end 35 and a second opening 40 at a second end 45. The first opening 30 is selectively fluid-connected to a high-pressure supply gas inlet line 50 via a valve 55 and to a low-pressure exhaust gas outlet line 60 via a valve 65. The second opening 40 is selectively fluid-connected to a high-pressure product outlet line 70 via a valve 75, to a medium-pressure vent gas outlet line 80 via a valve 85, and to a low-pressure purge gas inlet line 90 via a valve 95.

[0060] During the high-pressure parallel adsorption and product removal steps of the PSA cycle, valves 55 and 75 are open and valves 65, 85 and 95 are closed, allowing the high-pressure supply gas to enter the PSA adsorption vessel 10 and the high-pressure hydrogen flow to exit.

[0061] During at least one parallel flow depressurization step, valves 55, 65, 75, 85, and 95 are closed.

[0062] During the intermediate-pressure parallel flow decompression and vent removal steps, valve 85 is open, while valves 55, 65, 75, and 95 are closed.

[0063] During the counterflow blowdown step and the exhaust gas removal step, valve 65 is open, and valves 55, 75, 85, and 95 are closed. The floor is depressurized through valve 65, and some of the CO2 is desorbed.

[0064] During the counterflow purging and exhaust gas removal steps, valves 65 and 95 are open, and valves 55, 75, and 85 are closed. Purge gas is introduced, and CO2 is removed.

[0065] During at least one countercurrent repressurization step, valves 55, 65, 75, 85, and 95 are closed.

[0066] Figure 3 shows another embodiment of the hydrogen production process 250 of the present invention. Natural gas 105 and water 110 are sent to the reaction section 112 of the steam reforming process unit 120, and assist fuel gas 114 and air 115 are sent to the furnace 118 within the steam reforming process unit 120.

[0067] The reforming reaction produces an outflow stream 125 containing hydrogen, CO2, water, and at least one of methane, carbon monoxide, and nitrogen. Flue gas stream 130 and steam stream 135 also exit the steam reforming process unit 120.

[0068] The spillway 125 is sent to a hydrogen PSA unit 140, where it is separated into a hydrogen-rich, high-purity hydrogen stream 145 and a hydrogen-depleted exhaust gas stream 150 containing some hydrogen, CO2, water, and at least one of methane, carbon monoxide, and nitrogen.

[0069] The exhaust gas flow 150 is sent to the compressor 155. The compressed exhaust gas flow 160 is sent to the CO2 recovery system 165, where it is separated into a bottom flow 170 and a top flow 175. The bottom flow 170, which contains liquid CO2, is recovered.

[0070] The top flow 175 is sent to a PSA system 180 that generates at least two product flows, including two PSA units 205 and 210 in series. The top flow 175 is separated into a low-pressure CO2 flow 195 and a high-pressure flow 215 containing hydrogen and at least one of methane, carbon monoxide, and nitrogen. The low-pressure CO2 flow 195 is recycled to a compressor 155.

[0071] The high-pressure flow 215 is sent to a second PSA unit 210, where it is separated into a high-pressure hydrogen flow 190 and a low-pressure exhaust gas flow 200. The high-pressure hydrogen flow 190 is recovered. The low-pressure exhaust gas flow 200, which contains at least one of methane, carbon monoxide, and nitrogen, is sent to a steam reforming process unit 120 as fuel.

[0072] Bypass line 202 directs exhaust gas flow 150 to furnace 118 in steam reforming process unit 120 for combustion.

[0073] Figure 4 shows another embodiment of the hydrogen production process 300 incorporating the three-product PSA unit of the present invention. Natural gas 305, steam 310, and an oxygen stream 315 are fed to the ATR / GHR reaction unit 320. Other feed streams containing hydrocarbons that may be used instead of natural gas for the ATR / GHR, steam reforming, and POX processes include, but are not limited to, naphtha and liquefied petroleum gas (LPG). The POX and gasification processes may use solid feedstocks including, but not limited to, coal and petroleum coke.

[0074] The reforming reaction generates an effluent 325, which is sent to a water-gas shift reaction unit 330. The effluent 335 from the water-gas shift reaction unit 330 contains hydrogen, CO2, and at least one of methane, carbon monoxide, argon, and nitrogen.

[0075] The spill 335 is sent to the PSA unit 340, where it is separated into a hydrogen-rich, high-purity hydrogen stream 345 and a hydrogen-depleted exhaust gas stream 350 containing some hydrogen, CO2, as well as methane, carbon monoxide, nitrogen, and argon.

[0076] The exhaust gas flow 350 is sent to the compressor 355. The compressed exhaust gas flow 360 is sent to the CO2 recovery system 365, where it is separated into a bottom flow 370 and a top flow 375. The bottom flow 370, which contains liquid CO2, is recovered.

[0077] The top flow 375 is sent to a PSA system that generates at least two product flows 380, including a three-product PSA unit 385, where it is separated into three flows. The high-pressure hydrogen flow 390 is recovered. The low-pressure CO2 flow 395 is recycled to the compressor 355. The medium-pressure vent gas flow 400, containing methane, carbon monoxide, nitrogen, and argon, is sent to a combustion unit to generate the heat required for a portion of the steam flow 310. This combustion unit may be accompanied by a combustion heater or a waste heat boiler, or the gas flow may be used as fuel gas elsewhere in the facility.

[0078] Figure 5 shows another embodiment of the hydrogen production process 450 of the present invention. Natural gas 305, water vapor 310, and oxygen stream 315 are sent to the ATR / GHR reaction unit 320. The reforming reaction produces an effluent stream 325, which is sent to the water-gas shift reaction unit 330. The effluent 335 from the water-gas shift reaction unit 330 contains hydrogen, CO2, and at least one of methane, carbon monoxide, argon, and nitrogen.

[0079] The spill 335 is sent to the PSA unit 340, where it is separated into a hydrogen-rich, high-purity hydrogen stream 345 and a hydrogen-depleted exhaust gas stream 350 containing some hydrogen, CO2, as well as methane, carbon monoxide, nitrogen, and argon.

[0080] The exhaust gas flow 350 is sent to the compressor 355. The compressed exhaust gas flow 360 is sent to the CO2 recovery system 365, where it is separated into a bottom flow 370 and a top flow 375. The bottom flow 370, which contains liquid CO2, is recovered.

[0081] The top flow 375 is sent to a PSA system that generates at least two product flows 380, including a three-product PSA unit 385, where it is separated into three flows. The high-pressure hydrogen flow 390 is recovered. The low-pressure CO2 flow 395 is recycled to the compressor 355.

[0082] A medium-pressure vent gas stream 400 containing methane, carbon monoxide, nitrogen, and argon is sent to the catalytic oxidation reaction unit 405 along with a portion of the oxygen stream 315 415. The catalytic oxidation reaction of methane, carbon monoxide, and hydrogen forms a CO2 recirculation stream 425. A water stream 410 is used to cool the catalytic oxidation reaction unit 405 and generates a steam stream 420. The steam stream 420 is sent to the ATR / GHR reaction unit 320. The CO2 recirculation stream 425 is recirculated to the compressor 355. A bleed stream 430 is removed from the CO2 recirculation stream 425 to prevent the accumulation of impurities during the process. The water formed in the catalytic oxidation reaction unit 405 is removed as a stream 367 in a dryer downstream of the CO2 recovery system 365.

[0083] Figure 6 is a process flow diagram showing the design of a CO2 recovery system for removing carbon dioxide from hydrogen and lighter components of a synthesis gas flow. The process involves the use of a binary refrigerant CO2 fractional distillation process.

[0084] In this process, the inlet gas enters the plant as feed stream 931. Feed stream 931 is typically dehydrated to prevent hydrate (ice) formation under cryogenic conditions. Both solid and liquid desiccants have been used for this purpose.

[0085] The supply flow 931 is divided into two flows (flows 939 and 940). Flow 939 is cooled in heat exchanger 911 by heat exchange with cold carbon dioxide vapor (flow 938c) and low-temperature residual gas flow 933a. Flow 940 is cooled in heat exchanger 910 by heat exchange with column reboiler fluid (flow 936) and column-side reboiler fluid (flow 935). The cooled flows from heat exchangers 910 and 911 are recombined into flow 931a. Flow 931a is further cooled with a commercially available refrigerant 950 (e.g., propane or R-134A), and the resulting flow (cooled flow 931b) is expanded by expansion valve 912 to the operating pressure of the fractionation column 913, cools flow 931c, and is then introduced into the fractionation column 913 at its top column supply point.

[0086] The top vapor flow 932 exits the fractional column 913 and is cooled and partially condensed in the heat exchanger 914. The partially condensed flow 932a enters the separator 915, where the vapor (low-temperature residual gas flow 933) is separated from the condensed liquid flow 934. The condensed liquid flow 934 is pumped by pump 919 to a pressure slightly higher than the operating pressure of the fractional column 913, and then the liquid flow 934a enters the heat exchanger 916, where it is heated by heat exchange with carbon dioxide refrigerant from the bottom of the distillation column and partially vaporized (described below). The partially vaporized flow 934b is then fed into the fractional column 913 at the intermediate column feed point. If higher pressure and / or lower carbon dioxide content is desired in the feed to the PSA system, a cryogenic compressor (not shown) can be applied to the top vapor flow 932. If a compressor is used in this flow, the pump 919 can be eliminated, and the liquid from the separator 915 is sent to the fractionation column 913 via a liquid level control valve.

[0087] The fractionation column 913 is a conventional distillation column comprising multiple vertically spaced trays, one or more packed beds, or any combination of trays and packing. It also includes a reboiler (e.g., the aforementioned reboiler and side reboiler) which heats and vaporizes a portion of the liquid flowing down the column to provide stripping vapor, which flows up the column and strips the bottom-of-column liquid product flow 937 of hydrogen and lighter components. The trays and / or packing provide the necessary contact between the upward-rising stripping vapor and the downward-falling cryogenic liquid, and as a result the bottom-of-column liquid product flow 937 exits the bottom of the column based on reducing the concentrations of hydrogen and lighter components in the bottom product to produce a very pure carbon dioxide product.

[0088] The bottom-of-column liquid product flow 937 is mainly liquid carbon dioxide. A small portion (flow 938) is subcooled in the heat exchanger 916 by the liquid flow 934a from the separator 915, as described above. The subcooled liquid (flow 938a) is expanded to a lower pressure by the expansion valve 920, partially vaporized, and after further cooling of flow 938b, enters the heat exchanger 914. Flow 938b acts as a refrigerant in the heat exchanger 914, cooling the partially condensed flow 932a, as described above, and the resulting carbon dioxide vapor exits as flow 938c.

[0089] The cold carbon dioxide vapor (flow 938c) from the heat exchanger 914 is heated in the heat exchanger 911 by heat exchange with the feed gas as described above. The warm carbon dioxide vapor (flow 938d) is then compressed in three stages by compressors 921, 923, and 925 to a pressure higher than the pressure in the fractionation column 913, and cooled by exhaust coolers 922, 924, and 926 after each stage of compression. The compressed carbon dioxide flow (flow 938j) is then flash-expanded through valve 942 and returned to the bottom feed position in the fractionation column 913. The recirculated carbon dioxide (flow 938k) provides further heat load and stripping gas in the fractionation column 913. The remainder of the column bottom liquid product flow 937 (flow 941) is pumped to high pressure by pump 929 so that flow 941a forms a high-pressure carbon dioxide flow, which then flows into the pipeline or reinjection. In certain cases, the carbon dioxide flow needs to be delivered as a lower-pressure subcooled liquid that can be transported in an insulated transport container. In such cases, the carbon dioxide products (flow 941) are subcooled with refrigerant 950 in a heat exchanger 917 and then reduced to storage tank conditions. Therefore, the pump 929 is eliminated.

[0090] The low-temperature residual gas stream 933 exits the separator 915 and undergoes further cooling in the heat exchanger 914. The heated residual gas stream 933a is further heated after heat exchange with the supply gas in the heat exchanger 911 as described above. The warm residual gas stream 933b is then sent to the PSA system for further processing.

[0091] Figure 7 is a process flow diagram showing the design of a treatment unit for removing carbon dioxide from hydrogen and lighter components of a synthesis gas stream. In this process, the inlet gas enters the plant as feed stream 931. The process involves the use of a mixed refrigerant CO2 fractional distillation process.

[0092] The supply stream 931 is typically dehydrated to prevent hydrate (ice) formation under cryogenic conditions. Both solid and liquid desiccants have been used for this purpose.

[0093] The supply flow 931 is cooled in the heat exchanger 910 by heat exchange with the column reboiler fluid (flow 936) and the column side reboiler fluid (flow 935). Flow 931a is further cooled in the heat exchanger 911 by heat exchange with the low-temperature residual gas flow 933 and the flash-expanded multi-component mixed refrigerant flow consisting of both hydrocarbon and non-hydrocarbon components. The component mixture in the mixed refrigerant flow is designed to provide the most efficient cooling curve in the heat exchanger 911 based on the inlet gas supply conditions. The further cooled flow 931b is expanded by the expansion valve 912 to the operating pressure of the fractionation column 913 and sent to the fractionation column 913 at the intermediate column supply point.

[0094] The top vapor flow 932 exits the fractional column 913 and is cooled by a mixed refrigerant flow in the heat exchanger 911, where it is partially condensed. The partially condensed flow 932a enters the separator 915, where the vapor (low-temperature residual gas flow 933) is separated from the condensed liquid flow 934. The condensed liquid flow 934 is pumped by pump 919 to a pressure slightly higher than the operating pressure of the fractional column 913, and then the liquid flow 934a is sent to the fractional column 913 at the top feed point. If a higher pressure and / or lower carbon dioxide content is desired in the feed to the PSA system, a cryogenic compressor (not shown) can be applied to the top vapor flow 932. If a compressor is used in this flow, pump 919 can be eliminated, and the liquid from separator 915 is sent to the fractional column 913 via a liquid level control valve.

[0095] The fractionation column 913 is a conventional distillation column comprising multiple vertically spaced trays, one or more packed beds, or any combination of trays and packing. It also includes a reboiler (e.g., the aforementioned reboiler and side reboiler) which heats and vaporizes a portion of the liquid flowing down the column to provide stripping vapor, which flows up the column and strips the bottom-of-column liquid product flow 937 of hydrogen and lighter components. The trays and / or packing provide the necessary contact between the upward-rising stripping vapor and the downward-falling cryogenic liquid, and as a result the bottom-of-column liquid product flow 937 exits the bottom of the column based on reducing the concentrations of hydrogen and lighter components in the bottom product to produce a very pure carbon dioxide product.

[0096] The column bottom liquid product flow 937 is primarily liquid carbon dioxide. The column bottom liquid product flow 937 is pumped to high pressure by pump 929 so that flow 937a forms a high-pressure carbon dioxide flow, which then flows into a pipeline or reinjection. In certain cases, the carbon dioxide flow needs to be delivered as a lower-pressure subcooled liquid that can be transported in an insulated transport container. In such cases, the carbon dioxide products in the column bottom liquid product flow 937 are subcooled in a heat exchanger 911 by a mixed refrigerant 950 and then reduced to storage tank conditions. Therefore, pump 929 is eliminated.

[0097] The warm residual gas stream 933a exits the heat exchanger 911 after heat exchange with the supply gas as described above. The warm residual gas stream 933a is then sent to the PSA system for further processing. [Examples]

[0098] The following examples are intended to further illustrate the integration process. They are not intended to limit the claims of the present invention to the specific details of the examples.

[0099] Example 1 - PSA system including two PSA units Tables 1-10 show computer simulation results for PSA systems that generate at least two product flows, including two PSA units in series.

[0100] Table 1 shows a 6-bed cycle with three equalization steps for the first PSA unit. This is a simplified form of the overall PSA cycle (called a subcycle) and is routinely used by practitioners to obtain the minimum amount of information necessary to represent a complete multi-bed PSA cycle. These subcycles are repeated according to known procedures to create a complete cycle chart (each row corresponds to one bed). It is understood that other variations of the cycle details are possible. Table 2 provides a detailed description of the 6-bed subcycle in Table 1.

[0101] These cycles were used in computer simulations to obtain the results for the first two-product PSA unit 205 (Figure 3), shown in Tables 3-5.

[0102] [Table 1]

[0103] [Table 2] * x = subcycle time (range of 50 to 150 seconds)

[0104] Computer simulations were performed for the first PSA unit using the cycles shown in Tables 1 and 2. The feed gas composition is shown in Table 3, and the floor charging amount is shown in Table 4. As can be seen in Table 5, the low-pressure CO2 stream contains 99.6% of the CO2 and only 6.7% of the hydrogen in the top stream. The low-pressure CO2 stream also contains 25% CO, over 30% CH4, and 15% nitrogen. The third gas stream contains over 93% of the hydrogen and 0.4% of the CO2 in the top stream, along with 75% CO, over 65% CH4, and 85% nitrogen.

[0105] [Table 3]

[0106] [Table 4]

[0107] [Table 5]

[0108] Table 6 shows an 8-bed cycle with five pressure equalization steps for the second PSA unit, and Table 7 provides a detailed description of the 8-bed PSA cycle in Table 6.

[0109] These cycles were used in computer simulations to provide the results for the second two-product PSA unit 210 (Figure 3), as shown in Tables 8-10.

[0110] [Table 6]

[0111] [Table 7] * x = subcycle time (range of 30 to 150 seconds)

[0112] Computer simulations were performed for the second PSA unit using the cycles shown in Tables 6-7. The supply gas composition is shown in Table 8, and the floor charging amount is shown in Table 9. As shown in Table 10, the high-pressure hydrogen flow contains 90% of the hydrogen and 3% of the nitrogen in the supply flow to the second PSA unit, and does not contain any CO, CO2, or CH4. The low-pressure second gas flow (exhaust gas flow) contains the remaining 10% of the hydrogen, 97% of the nitrogen, and all of the CO2, CO, and CH4 in the supply flow to the second PSA unit.

[0113] [Table 8]

[0114] [Table 9]

[0115] [Table 10]

[0116] Example 2-3: PSA system containing product PSA units Tables 11-15 show experimental results for PSA systems containing three product PSA units.

[0117] Table 11 shows a 10-bed cycle with three pressure equalization steps. Table 12 provides a detailed explanation of the 10-bed PSA cycle in Table 11.

[0118] These cycles were used in experimental pilot plant tests of the three-product PSA unit 185 (Figure 1), as shown in Tables 13-15.

[0119] [Table 11]

[0120] [Table 12] * x = subcycle time (range of 30 to 120 seconds)

[0121] The supply gas composition is shown in Table 13, and the floor charging amount is shown in Table 14. As shown in Table 15, the high-pressure hydrogen stream contains 82.5% of the hydrogen in the incoming top stream and contains no CO2, CO, CH4, or nitrogen. The low-pressure CO2 stream contains all of the CO2, 8.8% hydrogen, 30.8% CO, 49.8% CH4, and 11.4% nitrogen. The medium-pressure vent gas stream contains 8.7% hydrogen, 69.2% CO, 50.2% CH4, and 88.6% nitrogen, and contains no CO2.

[0122] [Table 13]

[0123] [Table 14]

[0124] [Table 15]

[0125] As used herein, the term “flow” may include a variety of hydrocarbon molecules and other substances.

[0126] As used herein, the terms “flow,” “feed,” “product,” “part,” or “part” may include a variety of hydrocarbon molecules such as linear and branched alkanes, naphthalenes, alkenes, alkadienes, and alkynes, as well as optionally other substances, such as gases, such as hydrogen, or impurities, such as heavy metals, and sulfur and nitrogen compounds. Each of the above may also include aromatic and non-aromatic hydrocarbons.

[0127] As used herein, the term “top flow” may mean a flow taken out at or near the top of a container such as a column.

[0128] As used herein, the term “bottom flow” may mean a flow taken out at or near the bottom of a container such as a column.

[0129] As used herein, the term “unit” may refer to an area comprising one or more pieces of equipment and / or one or more subzones. Examples of such equipment include, but are not limited to, one or more reactors or reaction vessels, separation vessels, distillation columns, heaters, exchangers, pipes, pumps, compressors, and controllers. In addition, pieces of equipment such as reactors, dryers, or vessels may further comprise one or more zones or subzones.

[0130] The term “column” refers to one or more distillation columns for separating one or more different volatile components. Unless otherwise specified, each column includes a condenser at the top of the column to condense and reflux a portion of the top flow returning to the top of the column, and a reboiler at the bottom of the column to vaporize a portion of the bottom flow and return it to the bottom of the column. The feed into the column may be preheated. The top or overhead pressure is the pressure of the overhead vapor at the vapor outlet of the column. The bottom temperature is the liquid bottom outlet temperature. The net top line and net bottom line refer to the net lines from the column downstream of any reflux or reboiling into the column, unless otherwise specified. Stripping columns may omit the reboiler at the bottom of the column and instead provide heating requirements and separation propulsion from fluidizing inert media such as steam. Reboiling absorption columns may omit the condenser at the top of the column.

[0131] As illustrated, process flow lines in the diagram may be interchangeably referred to as, for example, lines, pipes, feed, gases, products, emissions, parts, sections, or flows.

[0132] The term "pass through" means that a material passes from a conduit or container to an object.

[0133] The terms "hydrogen enrichment" and "hydrogen-rich flow" mean that the hydrogen content / concentration of the product flow is higher than that of the inlet gas flow. For example, in some embodiments, the product flow may contain more than 40 mol%, or more than 50 mol%, or more than 60 mol%, or more than 70 mol%, or more than 80 mol%, or more than 90 mol%, or more than 95 mol%, or more than 98 mol%, or more than 99 mol%, or more than 99.9 mol% of hydrogen.

[0134] The terms "CO2 enrichment" and "CO2-rich flow" mean that the CO2 content / concentration of the product flow is higher than that of the inlet gas flow. For example, in some embodiments, the product flow may contain more than 40 mol%, or more than 50 mol%, or more than 60 mol%, or more than 70 mol%, or more than 80 mol%, or more than 90 mol%, or more than 95 mol%, or more than 98 mol%, or more than 99 mol%, or more than 99.9 mol% of CO2.

[0135] Specific Embodiments The following will be described in conjunction with specific embodiments, but it should be understood that this specification is intended to illustrate, and not limit, the scope of the foregoing description and the appended claims.

[0136] A first embodiment of the present invention is a method for producing a hydrogen enrichment product and recovering CO2, comprising the steps of: processing a feed stream containing hydrocarbons or carbonaceous raw materials in a hydrogen production process unit to produce a synthesis gas mixture containing hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon; and separating the effluent flow containing the synthesis gas from the hydrogen production process unit into a first high-pressure hydrogen stream rich in hydrogen and a hydrogen-depleted exhaust gas stream containing a portion of hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon; and hydrogen depletion The method includes the steps of: compressing a dry exhaust gas flow in a compressor to form a compressed exhaust gas flow; separating the compressed exhaust gas flow in a CO2 recovery system into a CO2 enrichment product flow and a top flow containing some hydrogen, some carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon; in a PSA system that generates at least two product flows, separating the top flow from the CO2 recovery system into a second high-pressure hydrogen flow rich in at least hydrogen and a low-pressure CO2 flow rich in carbon dioxide; recovering the second high-pressure hydrogen flow; and optionally recirculating the low-pressure CO2 flow to the compressor.One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the PSA system that generates at least two product flows comprises a three-product PSA unit, and the steps of separating the top flow from the CO2 recovery system include: introducing the top flow into the three-product PSA unit having a three-product PSA cycle; removing a second high-pressure hydrogen flow during a high-pressure co-current adsorption step in the three-product PSA cycle, wherein the second high-pressure flow is substantially free of carbon dioxide, methane, carbon monoxide, nitrogen, and argon; removing a second gas flow during a co-current depressurization step in the three-product PSA cycle, wherein the second gas flow contains at least one of methane, carbon monoxide, nitrogen, and argon; removing a low-pressure CO2 flow during at least one of a counter-current depressurization step and a counter-current purge step in the three-product PSA cycle; removing a second high-pressure hydrogen flow; and optionally recirculating the low-pressure CO2 flow to a compressor. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, which includes a three-product PSA unit having a three-product PSA cycle comprising a high-pressure co-current adsorption and hydrogen removal step, at least one co-current depressurization step following the high-pressure co-current adsorption and hydrogen removal step, at least one co-current depressurization and second gas removal step following the at least one co-current depressurization step, a countercurrent blowdown step and CO2 removal step following the medium-pressure co-current depressurization and second gas removal step, a countercurrent purging and CO2 removal step following the countercurrent blowdown step, at least one countercurrent repressurization step following the countercurrent purging and CO2 removal step, and optionally a co-current feed repressurization step following at least one countercurrent repressurization step, or a countercurrent product repressurization step following at least one countercurrent repressurization step.One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein a PSA system that generates at least two product flows includes a second PSA unit, and the step of separating the top flow from a CO2 recovery system is to introduce the top flow into the second PSA unit and separate the top flow into a low-pressure CO2 flow and a second high-pressure hydrogen flow, wherein the second high-pressure hydrogen flow includes more than 75% hydrogen and a portion of at least one of methane, carbon monoxide, nitrogen, and argon, and optionally recirculate the low-pressure CO2 flow to a compressor. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the PSA system generating at least two product streams further comprises a third PSA unit, and the method comprises the steps of separating a second high-pressure hydrogen stream in the third PSA unit into a third high-pressure hydrogen stream and a second gas stream, wherein the third high-pressure hydrogen stream substantially does not contain carbon dioxide, methane, carbon monoxide, nitrogen, and argon, and the second gas stream contains at least one of methane, carbon monoxide, nitrogen, and argon in the top stream, and recovering the third high-pressure hydrogen stream. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the CO2 recovery system comprises a refrigerated CO2 fractionation process, and the refrigeration is provided by at least two refrigeration circuits, one of which utilizes a portion of the CO2 enrichment product stream recovered from a distillation column in the CO2 recovery system, or by a single closed-loop multi-component mixed refrigerant circuit. One embodiment of the present invention is one, any, or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the steps of oxidizing methane, carbon monoxide, and optional hydrogen in a second gas stream with oxygen in a catalytic oxidation unit to produce water, CO2, and heat, and recirculating the CO2 from the catalytic oxidation unit to a compressor.One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the steps of selectively bypassing a compressor, a CO2 recovery system, and a PSA system that generates at least two product flows, and sending a hydrogen depletion flue gas flow from a hydrogen PSA unit to a combustion unit in a hydrogen production process unit. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the steps of a hydrogen production process including a WGS unit that generates a water-gas shift (WGS) effluent flow, the effluent flow from the hydrogen production process unit including a WGS effluent flow, the WGS effluent flow exchanging heat with a process flow to form cooled effluent steam and a preheated process flow, and recovering waste heat from the cooled effluent flow to generate steam using a process that includes a reversible oligomerization reaction of phosphoric acid. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the second high-pressure hydrogen stream has a pressure in the range of 1,000 kPa to 6,000 kPa. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the low-pressure CO2 stream has a pressure in the range of 100 kPa to 250 kPa. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the second gas stream has a pressure in the range of 100 kPa to 450 kPa. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, further comprising at least one of the steps of recirculating at least a portion of the second gas stream to a hydrogen production process unit, recirculating at least a portion of the second gas stream to a water-gas shift process unit, and sending at least a portion of the second gas stream to a combustion unit.One embodiment of the present invention is one, any, or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the steps of drying a compressed exhaust gas flow in a dryer to remove water, cooling the dried exhaust gas flow in a chiller to form a chilled exhaust gas flow, and then separating the exhaust gas flow, wherein separating the compressed exhaust gas flow includes separating the chilled exhaust gas flow. One embodiment of the present invention is one, any, or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the dried exhaust gas flow is cooled to a temperature of -20°C to -50°C. One embodiment of the present invention is one, any, or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the hydrogen production process unit comprises a novel or existing steam reforming unit having an optional gas-heated reformer, a self-thermal reforming unit having an optional gas-heated reformer, a partial oxidation unit, or a gasification unit.

[0137] A second embodiment of the present invention is a method for producing a hydrogen enrichment product and recovering CO2, comprising the steps of: processing a feed stream containing hydrocarbons or carbonaceous raw materials in a hydrogen production process unit to produce a synthesis gas mixture containing hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon; separating an outflow stream containing the synthesis gas mixture from the hydrogen production process unit into a first high-pressure hydrogen stream rich in hydrogen and a hydrogen-depleted exhaust gas stream containing a portion of hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon in a hydrogen pressure swing adsorption (PSA) unit; and compressing the hydrogen-depleted exhaust gas stream in a compressor to form a compressed exhaust gas stream. The method includes the steps of: drying the compressed exhaust gas flow in a dryer to remove water; cooling the dried exhaust gas flow to a temperature of -20°C to -50°C in a chiller to form a chilled exhaust gas flow; in a CO2 recovery system, separating the chilled exhaust gas flow into a CO2 enrichment product flow and a top flow containing some hydrogen, some carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon; in a PSA system that generates at least two product flows, separating the top flow from the CO2 recovery system into a second high-pressure hydrogen flow enriched with at least hydrogen and a low-pressure CO2 flow enriched with carbon dioxide; recovering the second high-pressure hydrogen flow; and recirculating the low-pressure CO2 flow to a compressor.

[0138] A third embodiment of the present invention is an apparatus for producing a hydrogen enrichment product and recovering CO2, comprising: a hydrogen production process unit having at least one inlet and at least one outlet; a hydrogen PSA unit having an inlet, a hydrogen outlet, and an exhaust gas outlet; a compressor having an inlet and an outlet, the inlet of which is in fluid communication with the outlet of the hydrogen production process unit; a dryer having an inlet and at least one outlet, the inlet of which is in fluid communication with the hydrogen PSA exhaust gas outlet; and a dryer having a gas inlet and a gas outlet, the inlet of which is in fluid communication with the outlet of the compressor. The apparatus includes a chiller having an inlet, a chilling fluid inlet, and a chilling fluid outlet, wherein the chiller's gas inlet is in fluid communication with the dryer's outlet and the chiller's fluid inlet is in fluid communication with a chilling fluid source; a CO2 recovery system having an inlet, a first outlet, and a top outlet, wherein the inlet of the CO2 recovery system is in fluid communication with the chiller's gas outlet; and a PSA system having at least an inlet, a high-pressure hydrogen outlet, and a low-pressure CO2 outlet, wherein the inlet of the PSA system is in fluid communication with the top outlet of the CO2 recovery system and the low-pressure CO2 outlet is in fluid communication with the compressor inlet. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the third embodiment of this paragraph, wherein the PSA system further includes a second gas outlet which is in fluid communication with a combustion unit in a hydrogen production process unit, or the second gas outlet of the PSA system is in fluid communication with the inlet of a catalytic oxidation unit, and the outlet of the catalytic oxidation unit is in fluid communication with the compressor inlet. One embodiment of the present invention is one or all of the preceding embodiments of this paragraph up to the third embodiment of this paragraph, wherein the PSA system includes a first PSA unit having an inlet and first and second outlets, and a second PSA unit having an inlet and first and second outlets, the inlet of the first PSA unit includes an inlet of the PSA system, the first outlet of the first PSA unit includes a low-pressure CO2 outlet, the inlet of the second PSA unit is in fluid communication with the second outlet of the first PSA unit, the first outlet of the second PSA unit includes a high-pressure hydrogen outlet, and the second outlet of the second PSA unit includes a second gas outlet.

[0139] Without further detail, it is expected that those skilled in the art will be able to utilize the invention to the fullest extent without departing from the spirit and scope of the invention, readily identify its essential characteristics, and make various changes and modifications to the invention to suit various uses and conditions. Accordingly, the prior preferred specific embodiments should be construed as merely illustrative and not to limit the remainder of this disclosure in any way, but are intended to cover various modifications and equivalent configurations that fall within the scope of the appended claims.

[0140] In the above, all temperatures are given in degrees Celsius, and all parts and percentages are based on weight unless otherwise specified.

Claims

1. To produce hydrogen enrichment products, ２ A method for recovering, A hydrogen production process unit (120) processes a feed stream (105) containing hydrocarbons or carbonaceous raw materials to produce an outflow stream (125) containing hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon. In a hydrogen pressure swing adsorption (PSA) unit (140), the outflow logistics (125) is separated into a first high-pressure hydrogen stream (145) rich in hydrogen and a hydrogen-depleted exhaust gas stream (150) containing a portion of the hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon. The hydrogen-depleted exhaust gas flow (150) is compressed in a compressor (155) to form a compressed exhaust gas flow (160). The steps include drying the compressed exhaust gas flow (160) in a dryer to remove water and form a dried exhaust gas flow, The steps of cooling the dry exhaust gas flow in a chiller to form a chilled exhaust gas flow, CO ２ In the recovery system (165), the chilled exhaust gas flow is treated with purified liquid CO2. ２ CO containing the product ２ A step of separating the enriched flow (170) into a top flow (175) containing a portion of the hydrogen, a portion of the carbon dioxide, and at least one of the methane, carbon monoxide, nitrogen, and argon, In a PSA system (180) that generates at least two product flows, the CO ２ The top flow (175) from the recovery system is divided into a second high-pressure hydrogen flow (190) which is rich in at least hydrogen and a low-pressure CO2 flow which is rich in carbon dioxide. ２ Steps to separate the flow (195), The steps of recovering the second high-pressure hydrogen stream (190) and The aforementioned low-pressure CO ２ Step of recirculating the flow (195) to the compressor (155) Methods that include...

2. The PSA system that generates at least two product flows includes a three-product PSA unit (185), and the CO ２ The step of separating the top flow (175) from the recovery system is, To introduce the top flow (175) into the three-product PSA unit (185) having a three-product PSA cycle, The removal of the second high-pressure hydrogen stream (190) during the high-pressure parallel adsorption step in the three-product PSA cycle, wherein the second high-pressure hydrogen stream (190) is substantially free of carbon dioxide, methane, carbon monoxide, nitrogen, and argon. The removal of a second gas stream (200) during the parallel depressurization step in the three-product PSA cycle, wherein the second gas stream (200) contains at least one of the methane, carbon monoxide, nitrogen, and argon. Removing the low-pressure CO stream (195) between at least one of the countercurrent pressure reduction step and the countercurrent purge step in the three-product PSA cycle ２ thereof; To recover the second high-pressure hydrogen stream (190), and The aforementioned low-pressure CO ２ The flow (195) is recirculated to the compressor (155). The method according to claim 1, including the method described in claim 1.

3. To produce hydrogen enrichment products, ２ A device for recovering, A hydrogen production process unit (120) having at least one inlet and at least one outlet for generating an outflow logistics (125) containing hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon. A hydrogen pressure swing adsorption (PSA) unit (140) having an inlet, a hydrogen outlet, and an exhaust gas outlet, wherein the inlet of the hydrogen pressure swing adsorption (PSA) unit is in fluid communication with the outlet of the hydrogen production process unit. A compressor (155) having an inlet and an outlet, wherein the inlet of the compressor is in fluid communication with the hydrogen PSA exhaust gas outlet, A dryer having an inlet and at least one outlet, wherein the inlet of the dryer is in fluid communication with the outlet of the compressor, A chiller having a gas inlet, a gas outlet, a chilling fluid inlet, and a chilling fluid outlet, wherein the gas inlet of the chiller is in fluid communication with the outlet of the dryer, and the fluid inlet of the chiller is in fluid communication with a chilling fluid source. CO2 with an inlet, a first outlet, and a tower top outlet ２ The recovery system (165) is the CO ２ The inlet of the recovery system is in fluid communication with the gas outlet of the chiller, CO ２ Recovery system (165), and At least an inlet, a high-pressure hydrogen outlet, and low-pressure CO2 ２ A PSA system (180) having an outlet, the inlet of the PSA system is the CO ２ The recovery system communicates with the top outlet of the tower and the low-pressure CO2. ２ A PSA system (180) that generates at least two product flows, the outlet of which is in fluid communication with the inlet of the compressor. A device including a device.

Images