Method for production of hydrogen-rich products and CO2 recovery in a hydrogen production process unit

Abstract

A process and apparatus for producing hydrogen-rich products and recovering CO2 from the effluent stream of a hydrogen production process unit are described. The process utilizes a CO2 recovery system integrated with a PSA system that produces at least two product streams to recover additional hydrogen and CO2 from the tail gas stream of a hydrogen PSA unit in a hydrogen production process.

Description

Technology Field

[0001] This application claims the benefit of U.S. provisional application serial number 63 / 167,338, filed on March 29, 2021, titled "Method for hydrogen production and CO2 recovery of a hydrogen production process unit," the entire contents of which are incorporated herein. Background Technology

[0002] Hydrogen is expected to have significant growth potential because it is a clean-combustion fuel. However, hydrogen production is traditionally a significant source of CO2 emissions, and government regulations and social pressures are increasingly encouraging CO2 capture or imposing taxes and fines on emissions. Consequently, significant competition is anticipated to lower the cost of hydrogen production while recovering byproduct CO2 for subsequent geological sequestration to capture the growing market. While CO2 can be separated into vapor for supply to conventional pipelines, it is highly likely that it must be produced in a liquefied form for easy transport by truck or ship due to the current lack of CO2 pipeline infrastructure in certain regions of the world.

[0003] The desired levels of mitigated CO2 emissions will vary depending on regional economic conditions, with some hydrogen producers prioritizing maximizing hydrogen production through CO2 capture, others prioritizing minimal CO2 emissions from hydrogen production, and some falling somewhere in between. Another important factor is the reformer technology selected for a given hydrogen production unit. For steam reformers, 50% to 60% CO2 capture may be sufficient, whereas over 90% or 95% may be expected for self-heating reformers (ATR), gasifiers, or partial oxidation (POX) reformers.

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

[0005] US 8,021,464 describes a process for producing hydrogen and CO2 together from a mixture of hydrocarbons converted into synthesis gas. The synthesis gas is separated into a hydrogen-enriched stream and a PSA off-gas stream in a PSA unit. The PSA off-gas is compressed and dried, followed by several successive stages of condensation and separation of a CO2-rich condensate with decreasing temperatures at each stage, ranging from ambient temperature to -56°C. However, the process results in a purge stream containing a significant amount of CO2 that must be removed from the process. A permeate module can be used to improve separation, but this comes at the cost of increased power requirements.

[0006] US 8,241,400 describes a process for recovering hydrogen and CO2 from a mixture of hydrocarbons using a system comprising a reformer unit, an optional water-gas shift reactor, a PSA unit, and a cryogenic purification unit or a catalytic oxidizer. The PSA unit produces three streams: a high-pressure hydrogen stream, a low-pressure CO2 stream, and a CH4-rich stream discharged during the CO2 co-purge step. During the process, CO2 purified in the CO2 purification unit is used as the co-purge for 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 stream is preferably introduced at a pressure higher than the pressure during the adsorption step.

[0007] The use of a second high-pressure feed stream (CO2 co-purge stream) increases the cost and complexity of the US 8,241,400 process. The need to have a split adsorber (or two separate vessels) with an isolation valve and an intermediate side-draw between the two further increases the cost and complexity of the process.

[0008] Therefore, there is a need for improved hydrogen production processes with improved and cost-effective CO2 recovery. Brief explanation of the drawing

[0009] FIG. 1 is an example of one embodiment of a method for producing hydrogen and recovering CO2 from a steam reforming process unit using a PSA system that produces at least two product streams of the present invention. FIG. 2 is an example of one embodiment of three production PSA units for use in a PSA system that produces at least two product streams of the present invention. FIG. 3 is an example of another embodiment of a method for producing hydrogen and recovering CO2 from a steam reforming process unit using another embodiment of a PSA system that produces at least two product streams of the present invention. FIG. 4 is an example of another embodiment of a method for producing hydrogen and recovering CO2 from an ATR process unit using a PSA system that produces at least two product streams of the present invention. FIG. 5 is an example of another embodiment of a method for producing hydrogen and recovering CO2 from an ATR process unit using a PSA system that produces at least two product streams of the present invention. FIG. 6 is an example of one embodiment of a CO2 recovery system using a dual refrigerant CO2 fractionation process. FIG. 7 is an example of another embodiment of a CO2 recovery system using a mixed refrigerant CO2 fractionation process. Specific details for implementing the invention

[0010] The process produces a hydrogen-rich product and allows for the recovery of CO2 from the effluent stream of the hydrogen production process unit. This uses a PSA system that produces at least two product streams to recover a hydrogen-rich product from the tail gas stream from the hydrogen separation unit in the hydrogen production process. The process utilizes a CO2 recovery system integrated with the PSA that produces at least two product streams to recover additional hydrogen and high-purity liquid CO2.

[0011] Extracting hydrogen-rich products (and pure hydrogen products in some embodiments) directly from the overhead stream of a CO2 recovery system having a PSA system that produces at least two product streams has the potential to provide economic advantages over systems using recycling configurations. Additional hydrogen production significantly improves process economics. Using a PSA system that produces at least two product streams from the CO2 recovery system overhead stream also prevents non-permeation losses of CO2 resulting from the use of membrane separation processes. Utilizing a PSA system that produces at least two product streams provides innovation and flexibility, reduces downstream equipment size and utilities, and can increase captured CO2 (since the impurity-rich purge stream does not contain significant CO2).

[0012] The hydrogen production process unit may include a new or existing steam reforming unit having a selective gas heating reformer, an autothermal reforming unit having a selective gas heating reformer, a gasification unit, or a partial oxidation (POX) unit. The hydrogen production process produces an effluent comprising hydrogen, carbon dioxide, water, and a mixture of gases including at least one of methane, carbon monoxide, nitrogen, and argon.

[0013] The effluent stream is initially sent to a hydrogen pressure swing adsorption (PSA) unit to separate it into a hydrogen-rich high-pressure hydrogen stream and a hydrogen-depleted tail gas stream containing the remainder 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 effluent that is recovered.

[0014] The hydrogen depletion tail gas stream is compressed and sent to a CO2 recovery system that separates it into a liquid CO2 product and an overhead stream containing hydrogen, some carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon.

[0015] 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 separates the overhead stream into at least two streams: a second high-pressure hydrogen stream and a low-pressure CO2 stream. The high-pressure hydrogen stream is hydrogen-rich. The low-pressure CO2 stream is carbon dioxide-rich. The second high-pressure hydrogen stream is recovered, and the low-pressure CO2 stream is recycled to a compressor.

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

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

[0018] The effluent is separated into a high-pressure hydrogen steam and a tail gas stream in a 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 at a pressure in the range of 2,000 to 5,000 kPa.

[0019] The tail gas stream from the 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 tail 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 tail gas stream is dried and cooled to a temperature of -20°C to -50°C. This is separated into a CO2-rich stream and an overhead stream containing hydrogen, some carbon dioxide, and some of at least one of methane, carbon monoxide, nitrogen, and argon. In some embodiments, the CO2-rich stream contains substantially all (e.g., 95% to 100%) of the CO2 in the tail gas stream from the hydrogen PSA unit and is substantially free of hydrogen, methane, carbon monoxide, nitrogen, and argon. In some embodiments, the CO2-rich stream comprises 95.0 mol% CO2 or more, 98.0 mol% CO2 or more, or 98.5 mol% CO2 or more, or 99.0 mol% CO2 or more, or 99.5 mol% CO2 or more, or 99.9 mol% CO2 or more.

[0021] The CO2 recovery system may include a distillation column, where a CO2-rich product stream is recovered from the bottom of the column and light components (hydrogen, methane, nitrogen, etc.) are recovered from the top of the column. Alternatively, the CO2 recovery system may also include single or multiple continuous flash vapor-liquid separation vessels, each separator providing an additional theoretical step of mass transfer, where the CO2-rich product is recovered from the liquid stream(s) and the light components (hydrogen, methane, nitrogen, etc.) are recovered from the overhead vapor stream(s).

[0022] The CO2-rich stream is recovered. The CO2-rich stream may be a liquid stream. In some cases, if desired, the liquid stream may be vaporized for use.

[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 3-product PSA unit having three product streams, a PSA unit having two product streams, or two PSA units each having two product streams, with the product stream supplied from the first PSA unit to the second PSA unit.

[0024] A 3-product PSA unit comprises four or more PSA adsorption vessels. Generally, there are at least six vessels, and generally eight to fourteen vessels. The vessels generally comprise one to five, and generally two to three, or more adsorbent layers. The proportion of the bed for the adsorbent layers is generally 10% to 100%. Different layers of adsorbents have different selectivity for components of the overhead stream, as is known to those skilled in the art. Some layers contain adsorbents for the selective adsorption of CO2 relative to methane, carbon monoxide, nitrogen, argon, and hydrogen, including but not limited to layers of activated alumina, silica gel, and sodium Y zeolite. Other layers contain adsorbents for the selective adsorption of CO2, methane, carbon monoxide, nitrogen, and argon relative to hydrogen, including but 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 know that other zeolites can be used and how to select appropriate adsorbents.

[0025] A first opening is located at one end of the vessel, and a second opening is located at the opposite end. For convenience, the ends will be referred to as the upper and lower portions of the vessel. At the lower portion, the first opening is optionally connected to a high-pressure supply gas inlet line and a low-pressure tail gas outlet line. At the upper portion, the second opening is optionally connected to a high-pressure product outlet line, an intermediate-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 the high pressure, co-current adsorption, and product removal steps occur with the product exiting 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 an intermediate pressure co-current depressurization and vent gas removal step. The second stream is removed at a second pressure through an opening at the top of the vessel. There are a counter-current blowdown step and a counter-current purge step. 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 one or both of the counter-current blowdown step and the counter-current purge step. There is at least one counter-current repressurization step after the counter-current purge and tail gas removal steps.

[0027] A PSA system producing at least two product streams may include one PSA unit having two product streams, or two PSA units each having two product streams in series. In a single PSA unit having two product streams, an overhead stream from a CO2 recovery system is fed into a PSA unit that separates into a CO2-rich low-pressure tail gas stream and a hydrogen-rich high-pressure stream (e.g., 85% to 95%). This may contain at least one of methane, carbon monoxide, nitrogen, and argon.

[0028] When two PSA units are connected in series, an overhead stream from a CO2 recovery system is fed into a first PSA unit having two product streams separated into a CO2-rich low-pressure tail gas stream and a high-pressure stream containing substantially all hydrogen (e.g., 85% to 95%) and some of at least one of methane, carbon monoxide, nitrogen, and argon. The high-pressure stream is fed into a second PSA unit having two product streams separated into a hydrogen-rich high-pressure hydrogen stream and a low-pressure stream containing substantially all methane, carbon monoxide, nitrogen, and argon (e.g., 95% to 100%).

[0029] The PSA system of the present invention, which produces at least two product streams, offers several advantages. The second stream is not removed at high pressure. In the case of a 3-product PSA unit, it is removed at an intermediate pressure between the high pressure at which hydrogen is removed and the low pressure at which CO2 is removed, but much closer to the low pressure than the high pressure. The intermediate pressure is generally less than 450 kPa. When the PSA system of producing at least two product streams comprises two PSA units, the second stream is generally removed at a low pressure of less than 250 kPa.

[0030] In addition, a high-pressure co-purge stream is not used. Furthermore, the vessel is not split; the second stream is discharged through an opening at the top of the vessel. Therefore, isolation valves and side outlets are not required between the two adsorbent beds. These factors make the 3-product PSA unit much less complex and cheaper to build and operate than the US 8,241,400 PSA and process.

[0031] The temperature of the overhead stream entering the PSA system producing at least two product streams (after cooling recovery and heat exchange) is generally in the range of 20°C to 60°C, 30°C to 50°C, 40°C (or any combination of temperature ranges).

[0032] The hydrogen concentration in the overhead stream supplied to a PSA unit having at least two product streams is generally in the range of 20 mol% to 60 mol%. For example, the hydrogen concentration in the overhead gas in a CO2 recovery system for the tail gas of a steam methane reforming plant is 30 mol% to 50 mol%.

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

[0034] The low-pressure tail gas stream is generally 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 generally contains substantially all (e.g., 95% to 100%) of the CO2 in the overhead stream. It generally contains 10% hydrogen (e.g., 5% to 15%) compared to the overhead stream, and 40% (e.g., 20% to 60%) of methane, carbon monoxide, nitrogen, and argon compared to the overhead stream.

[0036] When a PSA system producing at least two product streams includes a 3-product PSA unit, the second gas stream is removed at an intermediate pressure between high and low pressure, and the intermediate pressure is generally much closer to low pressure, within 400 kPa or 300 kPa or 200 kPa, than to high pressure. Generally, the intermediate pressure product stream is removed at a pressure in the range of 150 kPa to 450 kPa, or 250 kPa to 350 kPa. Although there is some overlap between the intermediate pressure range and the low pressure range, in certain cases, it is understood that the low pressure is lower than the intermediate pressure.

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

[0038] All or part of the second stream may be recirculated to a hydrogen production process unit, a water gas shift process unit, and / or a combustion unit.

[0039] When a PSA system producing at least two product streams includes one PSA unit, the overhead stream is introduced into a PSA unit that separates the low-pressure CO2 stream containing substantially all of CO2 (95% to 100%) and the high-pressure stream containing substantially all of hydrogen (e.g., more than 75%, or 85% to 95%) and a portion (50% to 90%) of at least one of methane, carbon monoxide, nitrogen, and argon. The low-pressure CO2 stream has a low pressure of 50 kPa to 250 kPa, or 100 kPa to 200 kPa. The high-pressure stream has a high pressure in the range of 1,000 to 6,000 kPa, or 2,000 kPa to 5,000 kPa, or 2,500 kPa to 4,500 kPa.

[0040] In the case where a PSA system producing at least two product streams comprises two PSA units in series, a high-pressure stream from the first PSA unit is supplied to a second PSA unit that separates into a high-pressure hydrogen stream containing substantially all hydrogen (e.g., 80% to 90%) and a second gas stream. The second gas stream contains substantially all of at least one of methane, carbon monoxide, nitrogen, and argon (e.g., 95% to 100%). The high-pressure hydrogen stream generally has a high pressure in the range of 1,000 to 6,000 kPa, or 2,000 kPa to 5,000 kPa, or 2,500 kPa to 4,500 kPa. In this arrangement, the second stream has a pressure in the range of 50 kPa to 250 kPa, or 100 kPa to 200 kPa.

[0041] The first PSA unit contains an adsorbent for the selective adsorption of CO2 for methane, carbon monoxide, nitrogen, argon, and hydrogen, comprising but not limited to layers of activated alumina, silica gel, and sodium Y zeolite. The second PSA unit contains an adsorbent for the selective adsorption of CO2, methane, carbon monoxide, nitrogen, and argon for hydrogen, comprising but 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 recognize that other zeolites may be used and will know how to select suitable adsorbents for the first and second PSA units.

[0042] If a PSA system producing at least two product streams includes a 3-product PSA unit, the high-pressure hydrogen stream can be removed during the high-pressure, parallel-flow adsorption stage of the PSA cycle, the second gas stream can be removed during the parallel-flow depressurization stage of the PSA cycle, and the low-pressure CO2 stream can be removed during the counter-flow depressurization stage and counter-flow purge stage of the PSA cycle.

[0043] In some embodiments, where the PSA system generating at least two product streams is a 3-product PSA unit, the PSA cycle is:

[0044] High-pressure parallel-flow adsorption and hydrogen removal step;

[0045] At least one parallel-current depressurization step after the high-pressure parallel-current adsorption step and the hydrogen removal step;

[0046] At least one parallel flow depressurization step followed by a parallel flow depressurization and a second gas removal step;

[0047] A backflow blowdown step and a CO2 removal step following the intermediate pressure parallel flow depressurization and secondary gas removal step;

[0048] Backflow purge and CO2 removal step after the backflow blowdown step;

[0049] At least one backflow repressurization step after the backflow purging and CO2 removal step; and

[0050] Optionally, it may include a co-flow supply repressurization step after at least one backflow repressurization step or a backflow product repressurization step after at least one backflow repressurization step.

[0051] In some embodiments, the CO2 recovery system comprises a cooled CO2 fractionation process, wherein the cooling is provided by: at least two cooling circuits in which one of the cooling circuits utilizes a portion of the liquid CO2 product recovered from the distillation column as described in detail below; or by a single closed-loop multi-component mixed refrigerant circuit.

[0052] In some embodiments, this process may include a catalytic oxidation (CATOX) reactor in a second stream to recover heat in the form of high-pressure steam from unconverted carbon monoxide and methane and unrecovered hydrogen generated in the hydrogen production process. Nearly the same amount of heat or steam is generated as when the second stream is sent to the furnace. However, sending it to the CATOX reactor unit prevents CO2 emissions that occur when burning these components in the furnace and increases the rate of CO2 captured in the process. The CATOX reactor unit may be approximately isothermal, with the catalyst on one side of the heat exchanger and boiling water on the other. For example, the water / steam (reactor) temperature of the CATOX reactor unit may be 250°C. The size of the reactor may be relatively small, and for example, if the hydrogen production plant capacity is 100,000 Nm3 / hr, the total gas feed rate (fuel gas + oxygen) may be 6,000 Nm3 / hr.

[0053] In some embodiments, there is an optional bypass arrangement that allows the system to operate when there is a problem with the compressor, the CO2 recovery system, or the PSA system that generates at least two product streams. In this case, the compressor, the CO2 recovery system, or the PSA system that generates at least two product streams is bypassed, and the tail gas stream from the hydrogen PSA unit is sent to the melting furnace of the hydrogen production process unit or elsewhere. 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 tail gas stream and the burner described in U.S. Application Serial No. 63 / 167,286 filed on the same date titled Active and Passive Combustion Stabilization of a Burner for Very Rapidly Changing Fuel Gas Composition, each of which is incorporated by reference in its entirety.

[0054] In this process, additional energy recovery can be obtained from the effluent of the WGS unit. The effluent stream of the WGS unit can be heat-exchanged with the process stream to form a cooled effluent stream and a preheated process stream. Using a process involving the reversible oligomerization reaction of phosphoric acid, waste heat can be recovered from the cooled effluent stream to generate steam. Contact between the waste heat and phosphoric acid leads to oligomerization into diphosphoric acid. As a result of oligomerization, water molecules are separated and condensed, cooling the waste heat. The pressure of the diphosphoric acid stream increases. The waste heat then evaporates the water absorbed by the diphosphoric acid. This causes deoligomerization and hydrolysis, converting it back into phosphoric acid and generating process heat of a higher value. The pressure of the phosphoric acid stream then decreases, and the cycle is repeated. The waste heat recovery process utilizing the reversible oligomerization of phosphoric acid is available from Qpinch in Antwerp, Belgium.

[0055] Another aspect of the present invention is an apparatus for producing a hydrogen-rich product and recovering CO2 from a hydrogen production process unit. In one embodiment, the apparatus comprises: 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 a tail gas outlet—wherein the hydrogen PSA unit inlet is in fluid communication with the hydrogen production process unit outlet—; a compressor having an inlet and an outlet—wherein the compressor inlet is in fluid communication with the hydrogen PSA tail gas outlet—; a CO2 recovery system having an inlet, a first outlet, and an overhead outlet—wherein the CO2 recovery system inlet is in fluid communication with the compressor outlet—; and a PSA system having at least an inlet, a high-pressure hydrogen outlet, and a low-pressure CO2 outlet, wherein the PSA system inlet is in fluid communication with the CO2 recovery system overhead outlet and the low-pressure CO2 outlet is in fluid communication with the compressor inlet.

[0056] In some embodiments, the device further comprises a dryer and a cooler located between a compressor and a CO2 recovery system; the dryer has an inlet and at least one outlet, and the dryer inlet is in fluid communication with the compressor outlet; the cooler has a gas inlet, a gas outlet, a cooling fluid inlet and a cooling fluid outlet, and the cooler gas inlet is in fluid communication with the dryer outlet and the cooler fluid inlet is in fluid communication with a cooling fluid source; and the inlet of the CO2 recovery system is in fluid communication with the cooler gas outlet.

[0057] In some embodiments, the PSA system further comprises a second gas outlet fluidly communicating with a combustion unit of a hydrogen production process unit; or the second gas outlet of the PSA system fluidly communicates with an inlet of a catalytic oxidation unit, and the outlet of the catalytic oxidation unit fluidly communicates with an inlet of a compressor.

[0058] In some embodiments, the PSA system comprises 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 comprises an inlet of the PSA system; the first outlet of the first PSA unit comprises a low-pressure CO2 outlet, and the inlet of the second PSA unit is in fluid communication with the second outlet of the first PSA unit; and the first outlet of the second PSA unit comprises a high-pressure hydrogen outlet, and the second outlet of the second PSA unit comprises a second gas outlet.

[0059] FIG. 1 illustrates an embodiment of a hydrogen production process (100) comprising a PSA system that produces at least two product streams, including a three-product PSA unit of the present invention. Natural gas (105) and water (110) are sent to a reaction section (112) of a steam reforming process unit (120), and auxiliary fuel gas (114) and air (115) are sent to a furnace (118) for combustion along with the air of the steam reforming process unit (120). Other feed streams containing hydrocarbons may be used instead of natural gas, including but not limited to naphtha and liquefied petroleum gas (LPG). The auxiliary fuel gas is an additional fuel source that provides stability and sufficient heat for the reforming reaction because the PSA tail gas or vent gas does not provide sufficient heat to drive the process. Suitable auxiliary fuel gases include, but are not limited to, other hydrocarbon-containing fuels, such as natural gas, refined fuel gas, petrochemical complex synthetic fuel gas, vaporized naphtha or vaporized liquefied petroleum gas (LPG), or mixtures of hydrogen and hydrocarbon-containing fuels including crude oil or refined hydrogen.

[0060] Steam reforming and water-gas shift reactions produce an effluent stream (125) containing at least one of hydrogen, CO2, water, and methane, carbon monoxide, and nitrogen. The flue gas stream (130) and the steam stream (135) also exit the steam reforming process unit (120).

[0061] The effluent stream (125) has a temperature of 30°C to 50°C (after heat recovery and cooling of the steam reforming process) and a pressure of 2,000 to 3,000 kPa. The effluent stream (125) is sent to a hydrogen PSA unit (140) which separates into a hydrogen-rich high-purity hydrogen stream (145) and a hydrogen-depleted tail gas stream (150) containing hydrogen, CO2, a portion of water, and at least one of methane, carbon monoxide, and nitrogen.

[0062] The tail gas stream (150) is sent to a compressor (155) which compresses the pressure from 110 kPa to 200 kPa to 3,000 kPa to 6,000 kPa.

[0063] The compressed tail gas stream (160) is dried to remove the water stream (167), cooled to a temperature of -20°C to -50°C, and sent to a CO2 recovery unit (165) that separates it into a lower stream (170) and an overhead stream (175). The lower stream (170), containing liquid CO2, is recovered.

[0064] The overhead stream (175) is sent to a PSA system (180) that produces at least two product streams, including a 3-product PSA unit (185) that separates into three streams. The high-pressure hydrogen stream (190) is recovered. The low-pressure CO2 stream (195) is recirculated to a compressor (155). An intermediate-pressure vent gas stream (200) containing at least one of methane, carbon monoxide and nitrogen and a small amount of hydrogen (e.g., less than 20%, or 10% to 20%) is sent to a steam reforming process unit (120) as fuel.

[0065] The bypass line (202) sends the tail gas stream (150) to the furnace (118) of the steam reforming process unit (120) for combustion. This allows the steam reforming process unit (120) to continue operating without CO2 recovery in the event of a problem with the compressor (155), the CO2 recovery unit (165), or the PSA system (180) that produces at least two product streams.

[0066] FIG. 2 illustrates a PSA unit (5) comprising a PSA adsorption vessel (10). The PSA adsorption vessel (10) comprises three adsorption layers (15, 20, 25). The PSA adsorption vessel (10) comprises a first opening (30) at a first end (35) and a second opening (40) at a second end (45). The first opening (30) is optionally fluid-connected to a high-pressure supply gas inlet line (50) via valve (55) and a low-pressure tail gas outlet line (60) via valve (65). The second opening (40) is optionally fluid-connected to a high-pressure product outlet line (70) via valve (75), an intermediate-pressure vent gas outlet line (80) via valve (85), and a low-pressure purge gas inlet line (90) via valve (95).

[0067] During the high pressure, in the parallel adsorption and product removal step of the PSA cycle, valves (55 and 75) are opened and valves (65, 85 and 95) are closed, allowing the high-pressure supply gas to enter the PSA adsorption vessel (10) and exit as a high-pressure hydrogen stream.

[0068] During at least one parallel depressurization step, the valves (55, 65, 75, 85, and 95) are closed.

[0069] During the intermediate pressure parallel flow depressurization and vent removal step, valve (85) is opened and valves (55, 65, 75, and 95) are closed.

[0070] During the backflow blowdown step and tail gas removal step, valve (65) is opened and valves (55, 75, 85, and 95) are closed. The bed is depressurized through valve (65), and some of the CO2 is removed.

[0071] During the backflow purge and tail gas removal steps, valves (65 and 95) are opened and valves (55, 75, and 85) are closed. Purge gas is introduced and CO2 is removed.

[0072] During at least one backflow repressurization step, the valves (55, 65, 75, 85, and 95) are closed.

[0073] FIG. 3 illustrates 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 auxiliary fuel gas (114) and air (115) are sent to the furnace (118) of the steam reforming process unit (120).

[0074] The reforming reaction produces an effluent stream (125) containing hydrogen, CO2, water, and at least one of methane, carbon monoxide, and nitrogen. The flue gas stream (130) and the steam stream (135) also exit the steam reforming process unit (120).

[0075] The effluent stream (125) is sent to a hydrogen PSA unit (140) which separates into a hydrogen-rich high-purity hydrogen stream (145) and a hydrogen-depleted tail gas stream (150) containing hydrogen, CO2, part of water and at least one of methane, carbon monoxide and nitrogen.

[0076] The tail gas stream (150) is sent to a compressor (155). The compressed tail gas stream (160) is sent to a CO2 recovery system (165) to be separated into a lower stream (170) and an overhead stream (175). The lower stream (170), containing liquid CO2, is recovered.

[0077] The overhead stream (175) is sent to a PSA system (180) that produces at least two product streams, including two PSA units (205, 210) in series. The overhead stream (175) is separated into a low-pressure CO2 stream (195) and a high-pressure stream (215) containing at least one of hydrogen and methane, carbon monoxide and nitrogen. The low-pressure CO2 stream (195) is recirculated to a compressor (155).

[0078] The high-pressure stream (215) is sent to a second PSA unit (210) which separates into a high-pressure hydrogen stream (190) and a low-pressure tail gas stream (200). The high-pressure hydrogen stream (190) is recovered. The low-pressure tail gas stream (200), containing at least one of methane, carbon monoxide, and nitrogen, is sent to a steam reforming process unit (120) as fuel.

[0079] The bypass line (202) sends the tail gas stream (150) to the furnace (118) of the steam reforming process unit (120) for combustion.

[0080] FIG. 4 illustrates another embodiment of a hydrogen production process (300) comprising a 3-product PSA unit of the present invention. Natural gas (305), steam (310), and oxygen stream (315) are sent to an ATR / GHR reaction unit (320). Other feed streams containing hydrocarbons that can 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.

[0081] The reforming reaction produces an effluent stream (325) 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.

[0082] The effluent (335) is sent to a PSA unit (340) which separates it into a hydrogen-rich high-purity hydrogen stream (345) and a hydrogen-depleted tail gas stream (350) containing hydrogen, some CO2, and methane, carbon monoxide, nitrogen, and argon.

[0083] The tail gas stream (350) is sent to a compressor (355). The compressed tail gas stream (360) is sent to a CO2 recovery system (365) for separation into a lower stream (370) and an overhead stream (375). The lower stream (370), containing liquid CO2, is recovered.

[0084] The overhead stream (375) is sent to a PSA system that produces at least two product streams (380), including a 3-product PSA unit (385) that separates into three streams. The high-pressure hydrogen stream (390) is recovered. The low-pressure CO2 stream (395) is recirculated to a compressor (355). An intermediate-pressure vent gas stream (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 stream (310). This combustion unit may include a heating heater or a waste heat boiler, or the gas stream may be used as fuel gas elsewhere in the facility.

[0085] FIG. 5 illustrates another embodiment of the hydrogen production process (450) of the present invention. Natural gas (305), steam (310), and oxygen stream (315) are sent to an ATR / GHR reaction unit (320). The reforming reaction produces an effluent stream (325) 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.

[0086] The effluent (335) is sent to a PSA unit (340) which separates it into a hydrogen-rich high-purity hydrogen stream (345) and a hydrogen-depleted tail gas stream (350) containing hydrogen, some CO2, and methane, carbon monoxide, nitrogen, and argon.

[0087] The tail gas stream (350) is sent to a compressor (355). The compressed tail gas stream (360) is sent to a CO2 recovery system (365) to be separated into a lower stream (370) and an overhead stream (375). The lower stream (370), containing liquid CO2, is recovered.

[0088] The overhead stream (375) is sent to a PSA system that produces at least two product streams (380), including a 3-product PSA unit (385) that separates into three streams. The high-pressure hydrogen stream (390) is recovered. The low-pressure CO2 stream (395) is recirculated to a compressor (355).

[0089] An intermediate pressure vent gas stream (400) containing methane, carbon monoxide, nitrogen, and argon is sent to a catalytic oxidation reaction unit (405) along with a portion (415) of an oxygen stream (315). 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 produces a steam stream (420). The steam stream (420) is sent to an ATR / GHR reaction unit (320). The CO2 recirculation stream (425) is recirculated to a compressor (355). A bleed stream (430) is removed from the CO2 recirculation stream (425) to prevent the accumulation of impurities in the process. The water formed in the catalytic oxidation reaction unit (405) is removed from the stream (367) of a downstream dryer of the CO2 recovery system (365).

[0090] FIG. 6 is a process flow diagram illustrating the design of a CO2 recovery system for removing carbon dioxide from hydrogen and light components in a synthesis gas stream. The process involves the use of a dual refrigerant CO2 fractionation process.

[0091] In this process, the inlet gas enters the plant as a feed stream (931). The feed stream (931) is typically dehydrated to prevent the formation of hydrates (ice) under cryogenic conditions. Both solid and liquid desiccants were used for this purpose.

[0092] The supply stream (931) is split into two streams (streams (939 and 940)). Stream (939) is cooled in a heat exchanger (911) by heat exchange with cold carbon dioxide vapor (stream (938c)) and cold residual gas stream (933a). Stream (940) is cooled in a heat exchanger (910) by heat exchange with column reboiler liquids (stream (936)) and column-side reboiler liquids (stream (935)). The cooled streams from the heat exchangers (910 and 911) are recombined into stream (931a). The stream (931a) is further cooled with a commercial refrigerant (950) (e.g., propane or R-134A), the resulting stream (cooled stream (931b)) is expanded by an expansion valve (912) to the operating pressure of the fractionation tower (913), and the stream (931c) is cooled before being supplied to the fractionation tower (913) at the top column feed point.

[0093] The overhead steam stream (932) leaves the fractionation tower (913), is cooled and partially condensed in the heat exchanger (914). The partially condensed stream (932a) enters a separator (915) where the steam (cold residual gas stream (933)) is separated from the condensed liquid stream (934). The condensed liquid stream (934) is pumped by a pump (919) to a pressure slightly higher than the operating pressure of the fractionation tower (913) before the liquid stream (934a) enters the heat exchanger (916), and is heated and partially vaporized by heat exchange with the carbon dioxide refrigerant at the bottom of the distillation column (described below). The partially vaporized stream (934b) is then supplied as a feed to the fractionation tower (913) at the intermediate column feed point. A cold compressor (not shown) may be applied to the overhead steam stream (932) if higher pressure and / or lower carbon dioxide content is required in the feed to the PSA system. If a compressor is used for this stream, the pump (919) can be removed, and the liquid from the separator (915) is sent to the fractionation tower (913) through the liquid level control valve.

[0094] The fractionation tower (913) is a conventional distillation column comprising a plurality of vertically spaced trays, one or more packing beds, or some combination of trays and packing. It also includes reboilers (like the previously described reboilers and side reboilers) that heat and vaporize a portion of the liquids flowing down the column to provide stripping vapors flowing up the column to remove hydrogen and light components from the column bottom liquid product stream (937). The trays and / or packing provide the necessary contact between the stripping vapors rising and the cold liquid falling down, so that the column bottom liquid product stream (937) exits the bottom of the tower based on reducing the concentration of hydrogen and lighter components of the bottom product to produce a very pure carbon dioxide product.

[0095] The column bottom liquid product stream (937) is mainly liquid carbon dioxide. A small portion (stream (938)) is supercooled in the heat exchanger (916) by the liquid stream (934a) from the separator (915) as described above. The supercooled liquid (stream (938a)) is expanded to a lower pressure by the expansion valve (920) and partially vaporized, and stream (938b) is further cooled before entering the heat exchanger (914). Stream (938b) functions as a refrigerant in the heat exchanger (914) to provide cooling of the partially condensed stream (932a) as described above, so that the resulting carbon dioxide vapor remains as stream (938c).

[0096] Cold carbon dioxide vapor (stream (938c)) from heat exchanger (914) is heated in heat exchanger (911) by heat exchange with the supply gas as described above. Then, warm carbon dioxide vapor (stream (938d)) is compressed in three stages by compressors (921, 923 and 925) to a pressure higher than that of the fractionation tower (913), and after each stage of compression, it is cooled by discharge coolers (922, 924 and 926). The compressed carbon dioxide stream (stream (938j)) is instantaneously expanded through valve (942) and returned to the lower supply position of the fractionation tower (913). The recirculated carbon dioxide (stream (938k)) provides additional heat and stripping gas in the fractionation tower (913). The remainder of the column bottom liquid product stream (937) (stream (941)) is pumped at high pressure by a pump (929) so that stream (941a) forms a high-pressure carbon dioxide stream and then flows into a pipeline or re-injection. In some cases, the carbon dioxide stream needs to be transferred to a lower-pressure supercooled liquid that can be transported in insulated shipping containers. In these cases, the carbon dioxide product (stream (941)) is supercooled with a refrigerant (950) in a heat exchanger (917) before going down to storage tank conditions. Therefore, the pump (929) is removed.

[0097] The cold residual gas stream (933) leaves the separator (915) and provides additional cooling to the heat exchanger (914). The warm 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.

[0098] FIG. 7 is a process flow diagram illustrating the design of a processing unit for removing carbon dioxide from hydrogen and lighter components from a synthesis gas stream. In this process, the inlet gas enters the plant as a feed stream (931). The process involves the use of a mixed refrigerant CO2 classification process.

[0099] The supply stream (931) is generally dehydrated to prevent the formation of hydrates (ice) under cryogenic conditions. Both solid and liquid desiccant agents were used for this purpose.

[0100] The supply stream (931) is cooled in the heat exchanger (910) by heat exchange with the column reboiler liquids (stream (936)) and the column-side reboiler liquids (stream (935)). The stream (931a) is further cooled in the heat exchanger (911) by heat exchange with the cold residual gas stream (933) and the flash-expanded multi-component mixed refrigerant stream containing both hydrocarbon and non-hydrocarbon components. The component mixture of the mixed refrigerant stream is designed to provide the most efficient cooling curve in the heat exchanger (911) based on the inlet gas supply conditions. The additionally cooled stream (931b) is expanded by the expansion valve (912) to the operating pressure of the fractionation tower (913) and sent to the fractionation tower (913) from the intermediate-column supply point.

[0101] The overhead steam stream (932) leaves the fractionation tower (913), is cooled, and partially condensed with the mixed refrigerant stream in the heat exchanger (911). The partially condensed stream (932a) enters a separator (915) where the steam (cold residual gas stream (933)) is separated from the condensed liquid stream (934). The condensed liquid stream (934) is pumped by a pump (919) to a pressure slightly higher than the operating pressure of the fractionation tower (913) before the liquid stream (934a) is sent to the fractionation tower (913) from the upper feed point. A cold compressor (not shown) may be applied to the overhead steam stream (932) if higher pressure and / or lower carbon dioxide content is required in the feed to the PSA system. If a compressor is used for this stream, the pump (919) may be removed, and the liquid in the separator (915) is sent to the fractionation tower (913) through a liquid level control valve.

[0102] The fractionation tower (913) is a conventional distillation column comprising a plurality of vertically spaced trays, one or more packing beds, or some combination of trays and packing. It also includes reboilers (like the previously described reboilers and side reboilers) that heat and vaporize a portion of the liquids flowing down the column to provide stripping vapors flowing up the column to remove hydrogen and light components of the column bottom liquid product stream (937). The trays and / or packing provide the necessary contact between the stripping vapors rising and the cold liquid falling down, so that the column bottom liquid product stream (937) exits the bottom of the tower based on reducing the concentration of hydrogen and lighter components of the bottom product to produce a very pure carbon dioxide product.

[0103] The column bottom liquid product stream (937) is primarily liquid carbon dioxide. The column bottom liquid product stream (937) is pumped to high pressure by a pump (929) so that the stream (937a) forms a high-pressure carbon dioxide stream and then flows into a pipeline or re-injection. In certain cases, the carbon dioxide stream must be transferred to a subcooled liquid at a lower pressure that can be transported in insulated shipping containers. In these cases, the carbon dioxide product of the column bottom liquid product stream (937) is subcooled with a mixed refrigerant (950) in a heat exchanger (911) before going down to storage tank conditions. Therefore, the pump (929) is removed.

[0104] The warm residual gas stream (933a) leaves 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.

[0105] Examples

[0106] 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.

[0107] Example 1 - PSA system including 2 PSA units

[0108] Tables 1 through 10 provide computer simulation results for a PSA system that produces at least two product streams including two PSA units in series.

[0109] Table 1 illustrates a 6-bed cycle with three pressure equalization stages for the first PSA unit. This is an abbreviated form of the entire PSA cycle (referred to as a sub-cycle) and is routinely used by physicians to capture the minimum necessary information to represent a complete multi-bed PSA cycle. These sub-cycles are replicated according to known procedures (where each row corresponds to one bed) to produce complete cycle charts. It is understood that other variations of cycle details are possible. Table 2 provides a detailed description of the 6-bed sub-cycle in Table 1.

[0110] These cycles were used in computer simulations to provide results for the first 2-product PSA unit (205) (Fig. 3) shown in Tables 3 to 5.

[0111] [Table 1]

[0112]

[0113] [Table 2]

[0114]

[0115] 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 bed loading is shown in Table 4. As can be seen in Table 5, the low-pressure CO2 stream contains only 99.6% CO2 and 6.7% hydrogen of the overhead stream. The low-pressure CO2 stream also contains 25% CO, more than 30% CH4, and 15% nitrogen. The third gas stream contains more than 93% hydrogen, 0.4% CO2, and 75% CO of the overhead stream, along with more than 65% CH4 and 85% nitrogen.

[0116] [Table 3]

[0117]

[0118] [Table 4]

[0119]

[0120] [Table 5]

[0121]

[0122] Table 6 illustrates an 8-bed cycle including five pressure equalization steps for the second PSA unit, and Table 7 provides a detailed description of the 8-bed PSA cycle of Table 6.

[0123] These cycles were used in computer simulations to provide results for the second 2-product PSA unit (210) (Fig. 3) shown in Tables 8 to 10.

[0124] [Table 6]

[0125]

[0126] [Table 7]

[0127]

[0128] Computer simulations were performed for the second PSA unit using the cycles shown in Tables 6 and 7. The feed gas composition is shown in Table 8, and the bed loading is shown in Table 9. As shown in Table 10, the high-pressure hydrogen stream contains 90% hydrogen and 3% nitrogen in the feed stream to the second PSA unit, and contains no CO, CO2, or CH4. The low-pressure second gas stream (tail gas stream) contains the remaining 10% hydrogen, 97% nitrogen, and all of CO2, CO, and CH4 in the feed stream to the second PSA unit.

[0129] [Table 8]

[0130]

[0131] [Table 9]

[0132]

[0133] [Table 10]

[0134]

[0135] Example 2 - PSA system including a 3-product PSA unit

[0136] Tables 11 to 15 provide experimental results for PSA systems containing 3-product PSA units.

[0137] Table 11 illustrates a 10-bed cycle with three pressure equalization stages. Table 12 provides a detailed description of the 10-bed PSA cycle of Table 11.

[0138] These cycles were used in experimental pilot plant tests of the 3-product PSA unit (185) (Fig. 1) shown in Tables 13 to 15.

[0139] [Table 11]

[0140]

[0141] [Table 12]

[0142]

[0143] The feed gas composition is shown in Table 13, and the bed loading is shown in Table 14. As shown in Table 15, the high-pressure hydrogen stream contains 82.5% hydrogen in the incoming overhead stream and contains no CO2, CO, CH4, or nitrogen. The low-pressure CO2 stream contains all 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.

[0144] [Table 13]

[0145]

[0146] [Table 14]

[0147]

[0148] [Table 15]

[0149]

[0150] As used herein, the term "stream" may include various hydrocarbon molecules and other substances.

[0151] As used herein, the terms “stream,” “feed,” “product,” “part,” or “part” may comprise various hydrocarbon molecules such as straight-chain and branched alkanes, naphthenes, alkenes, alkadienes, and alkynes, and optionally other substances such as, for example, hydrogen, or gases of impurities, heavy metals, and sulfur and nitrogen compounds. Each of the above may also comprise aromatic and non-aromatic hydrocarbons.

[0152] As used herein, the term "overhead stream" may mean a stream recovered from or near the top of a vessel, such as a column.

[0153] As used herein, the term "bottom stream" may mean a stream recovered from or near the bottom of a vessel, such as a column.

[0154] As used herein, the term “unit” may refer to an area comprising one or more equipment items and / or one or more sub-zones. Equipment items may include, but are not limited to, one or more reactors or reactor vessels, separation vessels, distillation towers, heaters, exchangers, pipes, pumps, compressors, and controllers. Additionally, equipment items, such as reactors, dryers, or vessels, may further comprise one or more zones or sub-zones.

[0155] The term “column” means a distillation column or columns for separating one or more components of different volatiles. Unless otherwise specified, each column includes a condenser in the overhead of the column for condensing and recirculating a portion of the overhead stream back to the top of the column, and a reboiler in the bottom of the column for vaporizing and recirculating a portion of the bottom stream back to the bottom of the column. Feeds to the columns 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. Unless otherwise shown, net overhead lines and net bottom lines refer to any downstream of recirculation or reboil to the column as net lines exiting the column. Stripping columns may omit the reboiler in the bottom of the column and instead provide heating requirements and separation stimuli from a fluidized inert medium such as vapor. Reboiled adsorber columns may omit the condenser in the top of the column.

[0156] As described, the process flow lines of the drawings may be referred to interchangeably as, for example, lines, pipes, supplies, gases, products, effluents, parts, parts, or streams.

[0157] The term "passage" means the passage of a substance from a conduit or container to an object.

[0158] The terms “hydrogen-rich” and “hydrogen-rich stream” mean that the hydrogen content / concentration of the product stream is higher than that of the inlet gas stream. For example, in some embodiments, the product stream 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%.

[0159] The terms “CO2 rich” and “CO2 rich stream” mean that the CO2 content / concentration of the product stream is higher than that of the inlet gas stream. For example, in some embodiments, the product stream 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%.

[0160] Specific Examples

[0161] The following description relates to specific embodiments, but it will be understood that this description is for illustrative purposes only and does not limit the scope of the foregoing description and the appended claims.

[0162] A first embodiment of the present invention is a method for producing a hydrogen-rich product and recovering CO2, comprising: processing a feed stream containing hydrocarbons or carbonaceous feedstock 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 effluent stream containing the synthesis gas from the hydrogen production process unit in a hydrogen pressure swing adsorption (PSA) unit into a hydrogen-rich first high-pressure hydrogen stream and a hydrogen-depleted tail gas stream containing the hydrogen, the carbon dioxide, a portion of the water, and at least one of the methane, the carbon monoxide, the nitrogen, and argon; compressing the hydrogen-depleted tail gas stream in a compressor to form a compressed tail gas stream; and separating the compressed tail gas stream in a CO2 recovery system into a CO2-rich stream containing a purified liquid CO2 product and an overhead stream containing the portion of the hydrogen, a portion of the CO2, and at least one of the methane, the carbon monoxide, the nitrogen, and argon. The method comprises the steps of: separating the overhead stream from the CO2 recovery system of the PSA system that produces at least two product streams into at least a hydrogen-rich second high-pressure hydrogen stream and a carbon dioxide-rich low-pressure CO2 stream; recovering the second high-pressure hydrogen stream; and optionally recirculating the low-pressure CO2 stream to the compressor.Embodiments of the present invention, from the prior embodiment of this paragraph to one, part or all of the first embodiment of this paragraph, wherein the PSA system producing at least two product streams comprises a 3-product PSA unit, and the step of separating the overhead stream from the CO2 recovery system comprises: introducing the overhead stream into the 3-product PSA unit having a 3-product PSA cycle; removing the second high-pressure hydrogen stream during the high-pressure, parallel-flow adsorption step of the 3-product PSA cycle—wherein the second high-pressure stream is substantially free of carbon dioxide, methane, carbon monoxide, nitrogen, and argon—; removing the second gas stream during the parallel-flow depressurization step of the 3-product PSA cycle—wherein the second gas stream comprises at least one of the methane, the carbon monoxide, the nitrogen, and the argon—; and removing the low-pressure CO2 stream during at least one of the reverse depressurization step and the reverse purge step of the 3-product PSA cycle. The step of recovering the second high-pressure hydrogen stream; and optionally the step of recirculating the low-pressure CO2 stream to the compressor.Embodiments of the present invention, as one, part or all of the prior embodiments of this paragraph to the first embodiment of this paragraph, a PSA system that generates at least two product streams comprises: a high-pressure, parallel-flow adsorption and hydrogen removal step; one or more parallel-flow depressurization steps after the high-pressure parallel-flow adsorption step and hydrogen removal step; a parallel-flow depressurization and second gas removal step after at least one parallel-flow depressurization step; a counter-flow blowdown step and CO2 removal step after the intermediate-pressure parallel-flow depressurization and second gas removal step; a counter-flow purging and CO2 removal step after the counter-flow blowdown step; at least one counter-flow repressurization step after the counter-flow purging and CO2 removal step; and optionally, a parallel-flow feed repressurization step after at least one counter-flow repressurization step or a counter-flow product repressurization step after at least one counter-flow repressurization step. Embodiments of the present invention, from the prior embodiment of this paragraph to one, part or all of the first embodiment of this paragraph, wherein the PSA system producing at least two product streams comprises a second PSA unit, and the step of separating the overhead stream from the CO2 recovery system comprises introducing the overhead stream into the second PSA unit and separating the overhead stream into the low-pressure CO2 stream and the second high-pressure hydrogen stream—wherein the second high-pressure hydrogen stream comprises more than 75% of the hydrogen, and a portion of at least one of the methane, the carbon monoxide, the nitrogen, and the argon—; and optionally recirculating the low-pressure CO2 stream to the compressor.Embodiments of the present invention, in part or in whole of the first embodiments of this paragraph from the prior embodiments of this paragraph, a PSA system generating at least two product streams further comprises a third PSA unit, and the method further comprises the step of separating the second high-pressure hydrogen stream of the third PSA unit into the third high-pressure hydrogen stream and the second gas stream—wherein the third high-pressure hydrogen stream is substantially free of carbon dioxide, methane, carbon monoxide, nitrogen, and argon, and the second gas stream comprises at least one of the methane, carbon monoxide, nitrogen, and argon of the overhead stream—; and the step of recovering the third high-pressure hydrogen stream. Embodiments of the present invention, in part or in whole of the first embodiments of this paragraph from the prior embodiments of this paragraph, a CO2 recovery system comprises a cooled CO2 fractionation process, and refrigeration cooling is provided by at least two cooling circuits in which one of the cooling circuits utilizes a portion of the CO2-rich product stream recovered from the distillation column of the CO2 recovery system; or by a single closed-loop multi-component mixed refrigerant circuit. Embodiments of the present invention further include, as one, part or all of the first embodiments of this paragraph from the prior embodiments of this paragraph, the step of oxidizing methane, carbon monoxide, and hydrogen of a second gas stream with oxygen in a catalytic oxidation unit to generate water, CO2, and heat; and the step of recirculating CO2 from the catalytic oxidation unit to a compressor. Embodiments of the present invention further include, as one, part or all of the first embodiments of this paragraph from the prior embodiments of this paragraph, the step of optionally bypassing a compressor, a CO2 recovery system, and a PSA system that generates at least two product streams, and the step of sending a hydrogen depletion tail gas stream from a hydrogen PSA unit to a combustion unit of a hydrogen production process unit.Embodiments of the present invention, in part or in whole of the first embodiment from the prior embodiment of this paragraph, comprise a hydrogen production process including a water gas shift (WGS) unit that generates a WGS effluent stream, and the effluent stream from the hydrogen production process unit includes the WGS effluent stream, and further comprises the step of heat-exchanging the WGS effluent stream with a process stream to form cooled effluent steam and a preheated process stream; and further comprises the step of recovering waste heat from the cooled effluent stream to generate steam using a process including a reversible oligomerization reaction of phosphoric acid. Embodiments of the present invention, in part or in whole of the first embodiment from the prior embodiment of this paragraph, comprise a second high-pressure hydrogen stream having a pressure in the range of 1,000 kPa to 6,000 kPa. Embodiments of the present invention, in part or in whole of the first embodiment from the prior embodiment of this paragraph, comprise a low-pressure CO2 stream having a pressure in the range of 100 kPa to 250 kPa. An embodiment of the present invention, in one, part or all of the prior embodiment to the first embodiment of this paragraph, wherein the second gas stream has a pressure in the range of 100 kPa to 450 kPa. An embodiment of the present invention, in one, part or all of the prior embodiment to the first embodiment of this paragraph, further comprises the step of recirculating at least a portion of the second gas stream to a hydrogen production process unit; the step of recirculating at least a portion of the second gas stream to a water gas shift process unit; and the step of sending at least a portion of the second gas stream to a combustion unit.Embodiments of the present invention, as one, part or all of the prior embodiments of this paragraph to the first embodiment of this paragraph, further comprise the step of drying a compressed tail gas stream in a dryer to remove water; and the step of cooling the dried tail gas stream in a cooler to form a cooled tail gas stream before separating the tail gas stream, wherein the step of separating the compressed tail gas stream comprises the step of separating the cooled tail gas stream. Embodiments of the present invention, as one, part or all of the prior embodiments of this paragraph to the first embodiment of this paragraph, the dried tail gas stream is cooled to a temperature of -20°C to -50°C. Embodiments of the present invention, as one, part or all of the prior embodiments of this paragraph to the first embodiment of this paragraph, the hydrogen production process unit comprises a new or existing steam reforming unit having a selective gas heating reformer, a self-heating reforming unit having a selective gas heating reformer, a partial oxidation unit, or a gasification unit.

[0163] A second embodiment of the present invention is a method for producing a hydrogen-rich product and recovering CO2, comprising the steps of: processing a feed stream containing a hydrocarbon or carbonaceous feedstock 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 effluent stream containing the synthesis gas mixture from the hydrogen production process unit in a hydrogen pressure swing adsorption (PSA) unit into a hydrogen-rich first high-pressure hydrogen stream and a hydrogen-depleted tail gas stream containing hydrogen, carbon dioxide, a portion of water, and at least one of methane, carbon monoxide, nitrogen, and argon; compressing the hydrogen-depleted tail gas stream in a compressor to form a compressed tail gas stream; drying the compressed tail gas stream in a dryer to remove water; and cooling the dried tail gas stream in a cooler to a temperature of -20°C to -50°C to form a cooled tail gas stream. The method comprises the steps of: separating a cooled tail gas stream of a CO2 recovery system into a CO2-rich product stream and an overhead stream comprising a portion of hydrogen, a portion of carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon; separating an overhead stream from a CO2 recovery system of a PSA system that produces at least two streams into a second high-pressure hydrogen stream rich in hydrogen and a low-pressure CO2 stream rich in carbon dioxide; recovering the second high-pressure hydrogen stream; and recirculating the low-pressure CO2 stream to a compressor.

[0164] A third embodiment of the present invention is an apparatus for producing a hydrogen-rich 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 a tail gas outlet—wherein the hydrogen PSA unit inlet is in fluid communication with the hydrogen production process unit outlet—; a compressor having an inlet and an outlet—wherein the compressor inlet is in fluid communication with the hydrogen PSA tail gas outlet—; a dryer having an inlet and at least one outlet—wherein the dryer is in fluid communication with the compressor outlet—; a cooler having a gas inlet, a gas outlet, a cooling fluid inlet, and a cooling fluid outlet—wherein the cooler gas inlet is in fluid communication with the dryer outlet, and the cooler fluid inlet is in fluid communication with a source of cooling fluid—; a CO2 recovery system having an inlet, a first outlet, and an overhead outlet—wherein the CO2 recovery system inlet is in fluid communication with the cooling gas outlet—; and comprises 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 fluidly connected to the overhead outlet of the CO2 recovery system, and the low-pressure CO2 outlet is fluidly connected to the inlet of the compressor. An embodiment of the present invention, as one, part or all of the prior embodiment of this paragraph or the first embodiment of this paragraph, further comprises a second gas outlet that is fluidly connected to the combustion unit of the hydrogen production process unit; or the second gas outlet of the PSA system is fluidly connected to the inlet of the catalytic oxidation unit, and the outlet of the catalytic oxidation unit is fluidly connected to the inlet of the compressor.Embodiments of the present invention, from the prior embodiments of this paragraph to one, part or all of the first embodiments of this paragraph, include a PSA system comprising 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 comprises an inlet of the PSA system; the first outlet of the first PSA unit comprises a low-pressure CO2 outlet; the inlet of the second PSA unit is fluidly connected to the second outlet of the first PSA unit; the first outlet of the second PSA unit comprises a high-pressure hydrogen outlet, and the second outlet of the second PSA unit comprises a second gas outlet. It is believed that those skilled in the art can make full use of the present invention by utilizing the foregoing description to make various changes and modifications to the present invention and to apply it to various uses and conditions without departing from the spirit and scope of the present invention.

[0165] It is understood that, without further detail, those skilled in the art can use the foregoing description to make full use of the invention and readily identify the essential features of the invention, and thus make various changes and modifications to the invention and adapt them to various uses and conditions without departing from the spirit and scope of the invention. Accordingly, the prior preferred specific embodiments are to be interpreted merely as illustrative and are not intended to limit the remainder of the disclosure in any way, but are intended to encompass various modifications and equivalent arrangements included within the scope of the appended claims.

[0166] In the foregoing, all temperatures are expressed in degrees Celsius, and unless otherwise specified, all parts and percentages are based on weight.

Claims

Claim 1 A method for producing a hydrogen-enriched product and recovering CO2, the method comprises: processing a feed stream (105) containing hydrocarbons or carbonaceous feedstock in a hydrogen production process unit (120) to produce a synthesis gas mixture containing hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon; separating an effluent stream (125) containing the synthesis gas from the hydrogen production process unit in a hydrogen pressure swing adsorption (PSA) unit (140) into a hydrogen-enriched first high-pressure hydrogen stream (145) and a hydrogen-depleted tail gas stream (150) containing a portion of the hydrogen, carbon dioxide, and water, and at least one of the methane, carbon monoxide, nitrogen, and argon; and separating the hydrogen-depleted tail gas stream (160) in a compressor (155) to form a compressed tail gas stream (160). A step of compressing a tail gas stream (150); a step of separating the compressed tail gas stream (160) in a CO2 recovery system (165) into a CO2-rich stream (170) containing a purified liquid CO2 product and an overhead stream (175) containing a portion of the hydrogen and a portion of the carbon dioxide and at least one of the methane, the carbon monoxide, the nitrogen and the argon; a step of separating the overhead stream (175) from the CO2 recovery system of a PSA system (180) that produces at least two product streams into a hydrogen-rich at least second high-pressure hydrogen stream (190) and a carbon dioxide-rich low-pressure CO2 stream (195); a step of recovering the second high-pressure hydrogen stream (190).A method comprising the step of optionally recirculating the low-pressure CO2 stream (195) to the compressor (155). Claim 2 In claim 1, the PSA system producing at least two product streams comprises a 3-product PSA unit (185) having three product streams, and the step of separating the overhead stream (175) from the CO2 recovery system comprises: introducing the overhead stream (175) into the 3-product PSA unit (185) having a 3-product PSA cycle; removing the second high-pressure hydrogen stream (190) during the high-pressure, co-current adsorption step of the 3-product PSA cycle—wherein the second high-pressure stream (190) is substantially free of carbon dioxide, methane, carbon monoxide, nitrogen, and argon—; removing the second gas stream (200) during the co-current depressurization step of the 3-product PSA cycle—wherein the second gas stream (200) is free of methane, carbon monoxide, nitrogen, and argon A method comprising: at least one of the above; removing the low-pressure CO2 stream (195) during at least one of the counter-current depressurization step and the counter-current purge step of the 3-product PSA cycle; recovering the second high-pressure hydrogen stream (190); and optionally recirculating the low-pressure CO2 stream (195) to the compressor (155). Claim 3 In an apparatus for producing a hydrogen-rich product and recovering CO2, the apparatus comprises: a hydrogen production process unit (120) having at least one inlet and at least one outlet; a hydrogen PSA unit (140) having an inlet, a hydrogen outlet and a tail gas outlet—wherein the inlet of the hydrogen PSA unit (140) is fluidly connected to the outlet of the hydrogen production process unit—; a compressor (155) having an inlet and an outlet—wherein the inlet of the compressor (155) is fluidly connected to the tail gas outlet of the hydrogen PSA; a dryer having an inlet and at least one outlet—wherein the inlet of the dryer is fluidly connected to the outlet of the compressor—; a cooler having a gas inlet, a gas outlet, a cooling fluid inlet and a cooling fluid outlet—wherein the cooler gas inlet is fluidly connected to the outlet of the dryer, and the cooler fluid inlet is fluidly connected to a source of cooling fluid—; a CO2 recovery system (165) having an inlet, a first outlet, and an overhead outlet—wherein the A device comprising a CO2 recovery system inlet that is fluidly connected to the cooler gas outlet; and a PSA system (180) having at least an inlet, a high-pressure hydrogen outlet, and a low-pressure CO2 outlet, wherein the PSA system inlet is fluidly connected to the CO2 recovery system overhead outlet, and the low-pressure CO2 outlet is fluidly connected to the compressor inlet. Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete

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