Oxycombustion in a method for recovering hydrogen-rich products and CO2 in a hydrogen generation unit

Abstract

A method for producing a hydrogen-enriched product and recovering CO2 is described. A synthesis gas stream from a hydrogen production process unit is separated into a high-pressure hydrogen stream and a hydrogen-depleted tail gas stream in a hydrogen pressure swing adsorption unit, and the hydrogen-depleted tail gas stream is compressed. The compressed tail gas stream is separated into a CO2-enriched product stream and an overhead stream in a CO2 fractionation system. The overhead stream is separated into a second high-pressure hydrogen stream and a low-pressure tail gas stream in an overhead hydrogen PSA system. The first and second high-pressure hydrogen streams and the CO2-enriched product stream are recovered. The low-pressure tail gas stream from the overhead hydrogen PSA system is combusted with oxygen to produce steam, electricity, or both.

Description

[Technical Field]

[0001] (Priority statement) This application claims priority to U.S. Provisional Patent Application No. 63 / 376,392, filed September 20, 2022, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Hydrogen is expected to have significant growth potential because it is a clean-burning fuel. However, hydrogen production has traditionally been a significant source of CO2 emissions, and government regulations and societal pressures are increasingly taxing or penalizing CO2 emissions or encouraging CO2 capture. As a result, significant competition is expected to drive down the cost of hydrogen production while capturing the by-product CO2 for subsequent geological sequestration to capture the growing market. While CO2 can be captured as a high-pressure gas delivered to a pipeline, it is often produced in a liquefied form for easy transportation by truck or ship due to the current lack of CO2 pipeline infrastructure in certain parts of the world.

[0003] There is growing interest in minimizing CO2 emissions from hydrogen production processes based on steam reforming, autothermal reforming, partial oxidation, or gasification of hydrocarbon or carbonaceous feedstocks. One approach to achieving this goal is to add CO2 capture to the process along with the recirculation of unconverted carbon-containing components (carbon monoxide and methane) within the process. Ideally, all of the unreacted carbon-containing components (carbon monoxide and methane) from the hydrogen production process would be converted to carbon dioxide by oxy-fuel combustion with capture of the resulting CO2 within the carbon capture section of the process. However, the presence of inert components, such as nitrogen and argon, in the hydrocarbon or carbonaceous feedstock or oxygen feed to such processes creates a problem with this approach. These inert components accumulate within the process and must be purged from the system, typically as a fuel gas stream. This purge stream also contains carbon-containing components (carbon dioxide, carbon monoxide, methane), resulting in carbon emissions to the atmosphere. Therefore, a method is needed to efficiently and selectively purge inert components from the process without increasing carbon emissions.

[0004] Most existing hydrogen production processes utilize pressure swing adsorption (PSA) to recover high-purity product hydrogen from shift syngas. The low-pressure exhaust gas stream from the PSA unit is typically combusted to generate heat for the process. If the stream is not sent to a combustor, a purge is required to prevent the buildup of inert gases during 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 converted to syngas. The syngas is separated in a PSA unit into a hydrogen-rich stream and a PSA off-gas stream. The PSA off-gas is compressed and dried, followed by several successive steps of condensing and separating a CO2-rich condensate, with the temperature being reduced with each step, the temperature of which ranges from ambient to -56°C. However, this process results in a purge stream containing significant amounts of CO2 that must be removed from the process. A permeate module 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 including a reformer unit, an optional water-gas shift reactor, a PSA unit, and a cryogenic purification unit or catalytic oxidation device. The PSA unit produces three streams: a high-pressure hydrogen stream, a low-pressure CO2 stream, and a CH4-rich stream that is removed during a CO2 co-purge step and can be recycled to the reformer unit. Purified CO2 from the CO2 purification unit in the process is used as a co-purge in the PSA unit. The adsorption step is carried out 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. The use of a second high-pressure feed stream (the CO2 co-purge stream) increases the cost and complexity of the process. The need to have a segmented adsorber (or two separate vessels) and have isolation valves between the two vessels and the intermediate side draw further increases the cost and complexity of the process.

[0007] WO 2021 / 175662 describes a hydrogen production process based on the reforming of a hydrocarbon feedstock, with hydrogen and CO2 being recovered from the process. The remaining gas, including unreacted carbon-containing components, is recycled within the process. As mentioned above, a problem with this approach is the carbon emissions caused by purging inert components (argon and / or nitrogen) from the recycle loop.

[0008] No hydrogen production facility has 100% conversion of hydrocarbon feedstocks to hydrogen, and these unconverted hydrocarbons result in additional carbon emissions from the process, which add to the carbon intensity of the hydrogen facility. Hydrogen facilities with carbon capture require large amounts of heat for the reforming reaction, as well as work in the form of steam or electricity to drive the numerous compressors required to sequester the captured CO2. The electricity and fuel requirements often result in increased carbon intensity, thus limiting the profitability of the technology.

[0009] Therefore, there is a need for improved hydrogen production processes that have reduced carbon intensity. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram of a low carbon intensity process for producing a hydrogen stream from a hydrogen production process involving oxy-fuel combustion to generate water vapor and capture carbon dioxide. [Figure 2] FIG. 1 is a diagram of another embodiment of a low carbon intensity process for producing a hydrogen stream from a hydrogen production process involving oxy-fuel combustion to generate steam and capture carbon dioxide. [Figure 3] FIG. 1 is a diagram of another embodiment of a low carbon intensity process for producing a hydrogen stream from a hydrogen production process involving oxy-fuel combustion to generate steam and capture carbon dioxide. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present process is unique because it utilizes oxygen from the air separation unit and off-gas from the process, as well as supplemental natural gas or other supplemental hydrocarbon-containing fuels, for oxy-fuel combustion, allowing existing carbon capture equipment to be utilized to reduce or eliminate all direct process carbon emissions from the plant. In addition, oxy-fuel combustion allows for the generation of steam and electricity needed by the rest of the process, further reducing or eliminating carbon intensity. This allows for higher credits to be given to the production facility for reduced carbon emissions (or clean hydrogen), making the unit more profitable.

[0012] The combustion gases, which are almost entirely CO2 and water vapor, can be directed to the suction of a hydrogen PSA exhaust gas compressor and mixed with the CO2-rich process stream from the hydrogen production process. Carbon dioxide from the combustion gases is then captured utilizing the same equipment as a process carbon capture system. Processes for CO2 capture can include cryogenic fractional distillation, amine solvent, or CO2 PSA.

[0013] In some embodiments, oxygen from an air separation unit (ASU) is combined with off-gas from the process and any additional methane / natural gas fuel and combusted to produce steam, which in turn generates electricity for the power requirements of the units in the process.

[0014] A feedstream comprising a hydrocarbon or carbonaceous feedstock is processed in a hydrogen production process unit, including, but not limited to, a steam reforming unit with an optional gas-heated reformer, an autothermal reforming unit with an optional gas-heated reformer, a gasification unit, or a partial oxidation (POX) unit, or combinations thereof.

[0015] The synthesis gas mixture produced in the hydrogen production process contains hydrogen, carbon monoxide, methane, water, and inert gases such as nitrogen and argon. The synthesis gas mixture undergoes a water-gas shift reaction to convert the carbon monoxide to carbon dioxide and additional hydrogen.

[0016] The hydrogen concentration in the synthesis gas stream is generally in the range of 50 mol% to 80 mol%. For example, the hydrogen concentration in a steam methane reforming plant shift syngas is 60 mol% to 80 mol%, while the hydrogen concentration in a POX reactor is 50 mol% to 70 mol%.

[0017] The shifted synthesis gas stream may optionally be cooled and water removed, for example in a gas-liquid separator, before entering the hydrogen PSA unit.

[0018] The temperature of the feed gas mixture entering the hydrogen PSA unit is typically in the range of 20°C to 60°C, or 30°C to 50°C, or 40°C (or any combination of temperature ranges).

[0019] The shifted synthesis gas is separated in a hydrogen PSA unit into a high-pressure hydrogen product stream and a low-pressure hydrogen-depleted gas stream. The high-pressure hydrogen product stream is recovered. 80% to 92% of the hydrogen in the synthesis gas mixture to the hydrogen PSA system is typically recovered in the high-pressure product stream, and in some cases, the high-pressure hydrogen stream is substantially free of CO2, methane, carbon monoxide, nitrogen, and argon. It typically contains less than 1%, or less than 0.1%, or less than 0.01% CO2 relative to the feed gas mixture. It typically contains less than 10%, or less than 5%, or less than 2%, or less than 1%, or less than 0.1% methane, carbon monoxide, nitrogen, and argon relative to the feed gas mixture. The high-pressure product stream is removed at high pressures, typically in the range of 1,000 to 6,000 kPa, or 2,000 to 5,000 kPa, or 2,500 to 4,500 kPa. The high pressure hydrogen product stream typically contains greater than 99.0 mol%, or greater than 99.9 mol%, or greater than 99.99 mol% hydrogen.

[0020] The low-pressure hydrogen-depleted exhaust gas stream contains a portion of the hydrogen, a portion of the carbon dioxide, and at least one of methane, carbon monoxide, water, nitrogen, and argon. The hydrogen-depleted exhaust gas stream is typically removed at a low pressure in the range of 50 kPa to 250 kPa, or 100 kPa to 200 kPa. The hydrogen-depleted exhaust gas stream typically contains 95% to 100% CO2 in the feed gas mixture. The hydrogen-depleted exhaust gas stream typically contains 10% hydrogen (e.g., 5% to 15%) relative to the feed gas mixture, and 70% to 100% methane, carbon monoxide, nitrogen, and argon relative to the feed.

[0021] The low-pressure hydrogen-depleted tail gas stream may be compressed, dried, and sent to a CO fractionation system where it is separated into a CO2-enriched product stream comprising a first portion of the carbon dioxide, and an overhead stream comprising a portion of the hydrogen, a second portion of the carbon dioxide less than the first portion of the carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon.

[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 then be vaporized for use.

[0023] The overhead stream is sent to an overhead hydrogen PSA system that produces at least two product streams. The overhead hydrogen PSA system separates the overhead stream into at least two streams: a second high-pressure hydrogen stream and a low-pressure tail gas stream. The high-pressure hydrogen stream is hydrogen-enriched. The low-pressure tail gas stream is carbon dioxide-enriched. The second high-pressure hydrogen stream is recovered.

[0024] The overhead PSA system can include a three-product PSA unit, a single two-product PSA unit, or two two-product PSA units in series.

[0025] When the overhead hydrogen PSA system includes a three-product PSA unit, the overhead stream is introduced into the three-product PSA unit to form a high-pressure hydrogen product stream, a carbon-enriched tail gas stream, and an inert gas-enriched vent gas stream.

[0026] A three-product PSA unit contains four or more PSA adsorption vessels. Generally, there are at least six vessels. The vessels contain one or more adsorbent layers, generally 1 to 5, typically 2 to 3 adsorbent layers. The bed percentage of the adsorbent layer 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 the selective adsorption of CO2 relative to methane, carbon monoxide, nitrogen, argon, and hydrogen, including, but not limited to, activated alumina, activated carbon, silica gel, and sodium Y zeolite layers. Other layers contain adsorbents for the selective adsorption of CO2, methane, carbon monoxide, nitrogen, and argon relative to hydrogen, including, but not limited to, activated carbon, silica gel, and molecular sieve zeolite (e.g., 5A or sodium X zeolite) layers. Those skilled in the art will understand that other zeolites may be used and will know how to select an appropriate adsorbent.

[0027] A first opening is located at one end of the vessel, and a second opening is located at the opposite end. For convenience, these ends are referred to as the top and bottom 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, an intermediate-pressure vent gas outlet line, and a low-pressure purge gas inlet line. Feed gas enters the vessel at high pressure through the first opening at the bottom, undergoes a high-pressure cocurrent adsorption and product removal step, and the product exits the vessel at high pressure through the second opening at the top of the vessel. There is at least one cocurrent depressurization step, followed by an intermediate-pressure cocurrent depressurization and vent gas removal step. A second stream is removed through an opening at the top of the vessel at a second pressure. There are a countercurrent blowdown step and a countercurrent purge step. Purge gas enters through an opening at the top of the vessel at a low pressure. The CO2 can be removed at low pressure through an opening in the bottom of the vessel during either or both of the countercurrent blowdown and countercurrent purge steps. Following the countercurrent purge and tail gas removal steps, there is at least one countercurrent repressurization step.

[0028] When the overhead PSA system includes at least two PSA units in series, the overhead stream from the CO fractionation system is introduced into the first PSA unit, where it is separated into a low-pressure tail gas stream enriched in CO, carbon monoxide, and methane (e.g., 80% to 100% recovery of CO, carbon monoxide, and methane from the overhead stream) and a high-pressure stream containing substantially all (e.g., greater than 75%, or 85% to 95%) of the hydrogen, a portion (50% to 90%) of the nitrogen, and argon. The low-pressure tail gas 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.

[0029] The high-pressure stream from the first PSA unit is fed to a second PSA unit where it is separated into a second high-pressure hydrogen stream containing substantially all of the hydrogen (e.g., 80% to 90%) and a second low-pressure tail gas stream containing a portion of the hydrogen (e.g., 10% to 20%) and a portion of the nitrogen and argon (e.g., 20% to 80%). The high-pressure hydrogen stream typically 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.

[0030] The first PSA unit contains an adsorbent for selective adsorption of CO relative to methane, carbon monoxide, nitrogen, argon, and hydrogen, including, but not limited to, layers of activated alumina, silica gel, and sodium Y zeolite. The second PSA unit contains an adsorbent for selective adsorption of CO, 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 understand that other zeolites can be used and will know how to select appropriate adsorbents for the first and second two-product PSA units.

[0031] In some embodiments, the process allows for recovery of 80-90% of the hydrogen in the exhaust gas stream from the hydrogen PSA unit, as well as capture of substantially all (e.g., 95%-100%) of the CO2.

[0032] The low pressure tail gas stream from the overhead PSA system is sent to a first fired heater oxy-fuel combustion unit where methane and carbon monoxide are combusted with oxygen to produce steam and / or electricity.

[0033] In some embodiments, a natural gas stream or other hydrocarbon-containing stream, such as liquefied petroleum gas, naphtha, or hydrocarbon-containing waste gas, may be delivered to the first fired heater as fuel.

[0034] The flue gas from the combustion heater oxy-fuel combustion unit is mixed with the hydrogen-depleted flue gas stream and sent to a CO2 fractionation system. A portion of the flue gas can be recirculated to control the temperature of the combustion heater oxy-fuel combustion unit.

[0035] The vent gas stream from the overhead tertiary PSA unit can be sent to a second fired heater and combusted with air to produce steam and / or electricity, or the vent gas stream can be sent to a fuel header or simply combusted.

[0036] In embodiments involving lean-burn combustion in the first combustion heater oxy-fuel combustion unit, oxygen can be removed from the low-pressure hydrogen-depleted compressed exhaust gas stream from the hydrogen PSA unit before drying the low-pressure hydrogen-depleted exhaust gas stream. Oxygen removal can be achieved in either a preferential oxidation unit or a deoxygenation unit. In both cases, a catalyst is used to consume oxygen to prevent it from entering the CO fractionation system and contaminating the product hydrogen. The preferential oxidation unit uses a platinum or ruthenium catalyst to selectively react carbon monoxide with oxygen, minimizing hydrogen consumption. Excess oxygen consumes hydrogen in the preferential oxidation unit. The deoxygenation unit is non-selective and consumes hydrogen and carbon monoxide. The deoxygenation catalyst is typically platinum or palladium.

[0037] In another embodiment, the synthesis gas stream from the hydrogen production process unit is sent to a hydrogen PSA unit where it is separated into a high pressure hydrogen stream and a hydrogen-depleted tail gas stream.

[0038] The hydrogen-depleted tail gas stream is compressed and sent to a CO2 PSA unit where it is separated into a CO2-enriched stream and an overhead stream containing a portion of the hydrogen, a portion of the carbon dioxide, and at least one of methane, carbon monoxide, nitrogen, and argon.

[0039] The overhead stream is sent to a second hydrogen PSA unit where it is separated into a hydrogen-enriched second high-pressure hydrogen stream and a low-pressure tail gas stream containing mostly methane, carbon monoxide, nitrogen, and argon, some hydrogen, and a small amount of carbon dioxide.

[0040] The CO2-enriched stream from the CO2 PSA unit, the low-pressure exhaust gas stream from the second hydrogen PSA unit, and oxygen from the air separation unit are sent to an oxy-fuel-fired combustion heater, optionally with supplemental natural gas fuel, to generate steam and / or electricity. Flue gas from the combustion heater is compressed and dried to provide a CO2 product stream.

[0041] One embodiment of an enrichment combustion process 100 is illustrated in Figure 1. A feed stream 105 is sent to a hydrogen production process unit 110. A syngas stream 115 is optionally cooled in a cooler 120, and the cooled syngas stream 125 is optionally sent to a knockout drum 130 where water 135 is separated from the cooled syngas stream 140.

[0042] The cooled synthesis gas stream 140 is sent to a hydrogen PSA unit 145 where it is separated into a first high pressure hydrogen product stream 150 and a hydrogen-depleted tail gas stream 155 .

[0043] The hydrogen-depleted tail gas stream 155 is compressed in compressor 160 to form compressed hydrogen-depleted tail gas stream 165 and dried in dryer 170. The dried, compressed hydrogen-depleted tail gas stream 175 is sent to a CO fractionation system 180 where it is separated into a CO-enriched product stream 185 and an overhead stream 190. The overhead stream 190 is sent to an overhead PSA system 195 where it is separated into a second high-pressure hydrogen product stream 200, a low-pressure tail gas stream 205, and a vent gas stream 210. The second high-pressure hydrogen product stream 200 is combined with the first high-pressure hydrogen product stream 150 and recovered as a combined hydrogen product stream 199.

[0044] The low pressure exhaust gas stream 205 , the natural gas stream 207 , and the oxygen stream 213 are sent to a first fired heater 215 and combusted to produce steam and / or electricity 220 .

[0045] A flue gas stream 225 from the first fired heater 215 is sent to the compressor 160 along with the hydrogen-depleted exhaust gas stream 155. A portion 230 of the flue gas stream 225 may be recirculated to the first fired heater to control the temperature of combustion in the fired heater (e.g., an adiabatic flame temperature of 1500°C to 2500°C).

[0046] Vent gas stream 210 and air stream 235 are sent to a second fired heater 240 to generate steam and / or electricity 245 and a second flue gas stream 250. Second flue gas stream 250 is released to the atmosphere.

[0047] One embodiment of the lean combustion process 300 is illustrated in Figure 2. A feed stream 305 is sent to a hydrogen production process unit 310. A syngas stream 315 is optionally cooled in a cooler 320, and the cooled syngas stream 325 is optionally sent to a knockout drum 330 where water 335 is separated from the cooled syngas stream 340.

[0048] The cooled synthesis gas stream 340 is sent to a hydrogen PSA unit 345 where it is separated into a first high pressure hydrogen product stream 350 and a hydrogen-depleted tail gas stream 355 .

[0049] Hydrogen-depleted tail gas stream 355 is compressed in compressor 360 to form compressed hydrogen-depleted tail gas stream 365 and dried in dryer 377. Prior to drying, compressed hydrogen-depleted tail gas stream 365 is sent to deoxygenation (DeOxo) unit 370. Deoxygenated and dried hydrogen-depleted tail gas stream 379 is sent to CO fractionation system 380 where it is separated into CO-enriched product stream 385 and overhead stream 390. Overhead stream 390 is sent to overhead PSA system 395 where it is separated into second high-pressure hydrogen product stream 400, low-pressure tail gas stream 405, and vent gas stream 410. Second high-pressure hydrogen product stream 400 is recovered along with first high-pressure hydrogen product stream 350.

[0050] The low pressure exhaust gas stream 405 , natural gas stream 407 , and oxygen stream 413 are sent to a first fired heater 415 and combusted to produce steam and / or electricity 420 .

[0051] A flue gas stream 425 from first fired heater 415 is sent to compressor 360 along with hydrogen-depleted exhaust gas stream 355. A portion 430 of flue gas stream 425 may be recycled to first fired heater 415.

[0052] The vent gas stream 410 and air stream 435 are sent to a second fired heater 440 to generate steam and / or electricity 445 and a second flue gas stream 450 .

[0053] 3 illustrates one embodiment of a process 500 including a CO2 PSA unit. A hydrocarbon feed stream 505 is sent to a hydrogen production process unit 510, where it is converted to a synthesis gas stream 515. The synthesis gas stream 515 is sent to a hydrogen PSA unit 520, where it is separated into a first high-pressure hydrogen product stream 525 and a hydrogen-depleted tail gas stream 530. The hydrogen-depleted tail gas stream 530 is compressed in a compressor 535. The compressed hydrogen-depleted tail gas stream 540 is sent to a CO2 PSA unit 545, where it is separated into a CO2-enriched stream 550 and an overhead stream 555. The overhead stream 555 is sent to a hydrogen PSA unit 560, where it is separated into a second high-pressure hydrogen stream 565 and a low-pressure tail gas stream 570.

[0054] A first high pressure hydrogen product stream 525 and a second high pressure hydrogen stream 565 are recovered.

[0055] Air stream 575 is separated into an oxygen stream 585 and a nitrogen stream in air separation unit 580. Air separation unit 580 may be, for example, a cryogenic separation unit. In some embodiments, a portion 587 of oxygen stream 585 may be sent to hydrogen production process unit 510.

[0056] CO2-enriched stream 550, low-pressure exhaust gas stream 570, and oxygen stream 585 are sent to a fired heater 590 to produce steam and / or electricity 595. Optionally, a portion 600 of hydrocarbon feed stream 505 can also be sent to fired heater 590 as additional fuel.

[0057] Flue gas 605 from fired heater 590 is compressed in compressor 610 and the compressed flue gas 615 is dried in dryer 630. Compressed, dried flue gas 635 can be recovered as a product CO2 stream.

[0058] Alternatively, in some embodiments, a deoxygenation (DeOxo) unit 620 is used upstream of the dryer 630 to remove oxygen, and the deoxygenated flue gas stream 635 is recovered as a product CO2 stream. [Example]

[0059] An example of the process of Figure 1 for hydrogen and carbon dioxide recovery from an autothermal reforming process is shown below in Table 1. The stream numbers in Table 1 correspond to the stream numbers in Figure 1. In this example, natural gas is the feedstock to the autothermal reforming process, and natural gas is also used as the auxiliary fuel gas (natural gas stream 207) in oxy-fuel fired combustion heater 215.

[0060] The results in Table 1 indicate that there are no direct CO2 emissions to the atmosphere associated with flue gas streams 225 and 250. The heat generated in fired heaters 215 and 240 provides 80 MW of heat duty (lower heating value basis) for the generation of high-pressure steam. This high-pressure steam is sufficient for the upstream autothermal reforming process, and this steam is also used to generate electricity in the steam turbine. The electricity generated in the steam turbine is sufficient to supply the entire power demand for the CO2 capture and hydrogen recovery process shown in Figure 1. Therefore, the entire process in Figure 1 is self-sufficient, with no direct CO2 emissions to the atmosphere.

[0061] [Table 1]

[0062] Specific Embodiments While the following will be described in conjunction with specific embodiments, it will be understood that this description is illustrative, but not intended to limit the scope of the preceding description and appended claims.

[0063] A first embodiment of the present invention is a method for producing a hydrogen-enriched product and recovering CO2, comprising: treating a feed stream comprising a hydrocarbon or carbonaceous feedstock in a hydrogen production process unit to produce a synthesis gas stream comprising hydrogen, carbon dioxide, and at least one of carbon monoxide, methane, water, nitrogen, and argon; separating the synthesis gas effluent stream in a hydrogen pressure swing adsorption (PSA) unit into a hydrogen-enriched first high-pressure hydrogen stream and a hydrogen-depleted tail gas stream comprising a portion of the hydrogen, a portion of the carbon dioxide, and at least one of methane, carbon monoxide, water, nitrogen, and argon; compressing the hydrogen-depleted tail gas stream in a compressor to form a compressed tail gas stream; and recovering CO2 from the compressed tail gas stream by treating the synthesis gas effluent stream with a hydrogen-enriched first high-pressure hydrogen stream and a hydrogen-depleted tail gas stream comprising a portion of the hydrogen, a portion of the carbon dioxide, and at least one of methane, carbon monoxide, water, nitrogen, and argon. separating the overhead stream from the CO2 fractionation system into a hydrogen-enriched second high-pressure hydrogen stream and a low-pressure tail gas stream comprising the second portion of the carbon dioxide, methane, carbon monoxide, and a first portion of the nitrogen and argon in an overhead hydrogen PSA system; recovering the first and second high-pressure hydrogen streams and the CO2-enriched product stream; and combusting the low-pressure tail gas stream from the overhead hydrogen PSA system and oxygen in a first fired heater to produce steam, electricity, or both, and a first flue gas stream. An embodiment of the invention is one, any, or all of the previous embodiment of this paragraph through the first embodiment of this paragraph, further including: recycling at least a first portion of the first flue gas to the first fired heater; or introducing at least a second portion of the first flue gas to a CO fractionation system; or both.An embodiment of the present invention is any one, any, or all of the embodiments from the previous embodiment in this paragraph to the first embodiment in this paragraph, wherein separating the overhead stream from the CO fractionation system in the overhead hydrogen PSA system includes separating the overhead stream from the CO fractionation system into at least a hydrogen-enriched second high-pressure hydrogen stream, a low-pressure exhaust gas stream, and a vent gas stream containing a portion of the hydrogen in the overhead stream and at least a second portion of the nitrogen and argon, and further including combusting the vent gas stream with air in a second fired heater to produce steam, electricity, or both, and a second flue gas stream, and / or introducing the vent gas to a fuel header. An embodiment of the present invention is any one, any, or all of the embodiments from the previous embodiment in this paragraph to the first embodiment in this paragraph, further including removing oxygen from the compressed exhaust gas stream prior to separating the compressed exhaust gas stream. An embodiment of the present invention is one, any, or all of the embodiments from the previous embodiment to the first embodiment of this paragraph, further comprising introducing natural gas into the first fired heater. An embodiment of the present invention is one, any, or all of the embodiments from the previous embodiment to the first embodiment of this paragraph, further comprising venting a portion of the first flue gas to the atmosphere. An embodiment of the present invention is one, any, or all of the embodiments from the previous embodiment to the first embodiment of this paragraph, further comprising drying the compressed flue gas stream prior to separating it in the CO fractionation system. An embodiment of the present invention is one, any, or all of the embodiments from the previous embodiment to the first embodiment of this paragraph, further comprising compressing a portion of the flue gas stream from the overhead hydrogen PSA system and combining the portion with the CO2-enriched product stream. An embodiment of the invention is one, any, or all of the previous embodiment of this paragraph through the first embodiment of this paragraph, further comprising cooling the syngas stream and removing a portion of the water from the syngas stream prior to separating the syngas stream in the hydrogen high-pressure PSA unit.An embodiment of the present invention is one, any, or all of the embodiments from the previous embodiment in this paragraph to the first embodiment in this paragraph, wherein the overhead hydrogen PSA system includes a three-product PSA unit or two PSA units connected in series.

[0064] A second embodiment of the present invention is a method for producing a hydrogen-enriched product and recovering CO2, comprising: treating a feed stream comprising a hydrocarbon or carbonaceous feedstock in a hydrogen production process unit to produce a synthesis gas stream comprising hydrogen, carbon dioxide, and at least one of carbon monoxide, methane, water, nitrogen, and argon; separating the synthesis gas stream in a hydrogen pressure swing adsorption (PSA) unit into a hydrogen-enriched first high-pressure hydrogen stream and a hydrogen-depleted tail gas stream comprising hydrogen, carbon dioxide, a portion of the 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; and recovering the compressed tail gas stream in a CO2 PSA unit to separate the CO2-enriched stream and the hydrogen, a portion of the carbon dioxide, and the methane, carbon monoxide, nitrogen, and argon. separating the overhead stream from the CO2 PSA unit in a second hydrogen PSA unit into a hydrogen-enriched second high-pressure hydrogen stream and a low-pressure tail gas stream comprising at least one of methane, carbon monoxide, nitrogen, and argon, and a portion of the carbon dioxide; recovering the first high-pressure hydrogen stream and the second high-pressure hydrogen stream; separating air in an air separation unit to produce an oxygen stream; introducing the natural gas stream, the CO2-enriched stream, the low-pressure tail gas stream from the second hydrogen PSA unit, and the oxygen stream from the air separation unit to a fired heater to produce steam, electricity, or both, and a flue gas stream comprising carbon dioxide; compressing and drying the flue gas stream; and recovering the compressed flue gas stream as a CO2 product stream. An embodiment of the invention is one, any, or all of the embodiments from the previous embodiment to the second embodiment of this paragraph, further comprising removing oxygen from the compressed flue gas stream prior to recovering the compressed flue gas stream.An embodiment of the invention is one, any, or all of the embodiments from the previous embodiment to the second embodiment of this paragraph, further comprising introducing a portion of the oxygen stream from the air separation unit into the hydrogen production process unit.

[0065] Without further elaboration, it is believed that, using the preceding description, one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of the present invention, and can make various changes and modifications to the present invention to adapt it to various uses and conditions, without departing from the spirit and scope of the present invention. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0066] Above, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

Claims

1. producing a hydrogen-rich product and CO ２ A method for recovering processing a feed stream (105) comprising a hydrocarbon or carbonaceous feedstock in a hydrogen production process unit (110) to produce a synthesis gas stream (115) comprising hydrogen, carbon dioxide, and at least one of carbon monoxide, methane, water, nitrogen, and argon; separating the synthesis gas stream (115) in a hydrogen pressure swing adsorption (PSA) unit (145) into a hydrogen-enriched first high-pressure hydrogen stream (150) and a hydrogen-depleted tail gas stream (155) comprising a portion of the hydrogen, a portion of the carbon dioxide, and the at least one of the methane, the carbon monoxide, the water, the nitrogen, and the argon; compressing the hydrogen-depleted exhaust gas stream (155) in a compressor (160) to form a compressed exhaust gas stream (165); The compressed exhaust gas stream (165) is ２ a fractionation system (180) for separating CO 2 containing a first portion of said carbon dioxide; ２ an enriched product stream (185) and an overhead stream (190) comprising said portion of said hydrogen, a second portion of said carbon dioxide, and said at least one of said methane, said carbon monoxide, said nitrogen, and said argon; The CO ２ separating the overhead stream (190) from the fractionation system (180) in an overhead hydrogen PSA system (195) into at least a hydrogen-enriched second high-pressure hydrogen stream (200) and a low-pressure tail gas stream (205) comprising the second portion of the carbon dioxide, the methane, the carbon monoxide, and a first portion of the nitrogen and the argon; The first high-pressure hydrogen stream and the second high-pressure hydrogen stream (150, 200) and the CO ２ recovering an enriched product stream (185); combusting the low-pressure tail gas stream (205) from the overhead hydrogen PSA system (195) and oxygen (213) in a first fired heater (215) to produce steam, electricity, or both, and a first flue gas stream (225).

2. recirculating at least a first portion (230) of the first flue gas stream (225) to the first fired heater (215); or at least a second portion (299) of said first flue gas stream (225) ２ introducing the fractionated product into a fractionation system (180); or both.

3. In the overhead hydrogen PSA system (195), ２ Separating the overhead stream (190) from the fractionation system (180) ２ separating the overhead stream (190) from a fractionation system (180) into at least the hydrogen-enriched second high-pressure hydrogen stream (200), the low-pressure tail gas stream (205), and a vent gas stream (210) comprising a portion of the hydrogen in the overhead stream, the nitrogen, and at least a second portion of the argon; combusting the vent gas stream (210) with air (235) in a second fired heater (240) to produce steam, electricity, or both, and a second flue gas stream; or introducing said vent gas stream (210) into a fuel header; or The method of any one of claims 1 to 2, further comprising:

4. The method of any one of claims 1 to 2, further comprising removing oxygen from the compressed exhaust gas stream (365) prior to separating the compressed exhaust gas stream (365).

5. The method of any one of claims 1 to 2, further comprising introducing natural gas (207) into the first fired heater (215).

6. The CO ２ The method of any one of claims 1 to 2, further comprising drying the compressed exhaust gas stream (165) prior to separating the compressed exhaust gas stream (165) in a fractionation system (180).

7. The method of any one of claims 1 to 2, wherein the overhead hydrogen PSA system (195) comprises a three-product PSA unit.

8. 3. The method of claim 1, further comprising cooling (120) the synthesis gas stream (115) and removing a portion of the water (135) from the synthesis gas stream (115) prior to separating the synthesis gas stream (115) in the hydrogen high-pressure PSA unit (145).

9. producing a hydrogen-rich product and CO ２ A method for recovering processing a feed stream (505) comprising a hydrocarbon or carbonaceous feedstock in a hydrogen production process unit (510) to produce a synthesis gas stream (515) comprising hydrogen, carbon dioxide, and at least one of carbon monoxide, methane, water, nitrogen, and argon; separating the synthesis gas stream (515) in a hydrogen pressure swing adsorption (PSA) unit (520) into a hydrogen-enriched first high-pressure hydrogen stream (525) and a hydrogen-depleted tail gas stream (530) comprising the hydrogen, the carbon dioxide, a portion of the water, and the at least one of the methane, the carbon monoxide, the nitrogen, and the argon; compressing the hydrogen-depleted exhaust gas stream (530) in a compressor (535) to form a compressed exhaust gas stream (540); CO ２ The compressed exhaust gas stream (540) is treated in a PSA unit (545) with CO ２ an enriched product stream (550) and an overhead stream (555) comprising said portion of said hydrogen, said portion of said carbon dioxide, and said at least one of said methane, said carbon monoxide, said nitrogen, and said argon; The CO ２ separating the overhead stream (555) from the PSA unit (545) in a second hydrogen PSA unit (560) into a hydrogen-enriched second high-pressure hydrogen stream (565) and a low-pressure tail gas stream (570) comprising the at least one of the methane, the carbon monoxide, the nitrogen, and the argon and a portion of the carbon dioxide; recovering the first high-pressure hydrogen stream and the second high-pressure hydrogen stream (525, 565); Separating air (575) in an air separation unit (580) to produce an oxygen stream (585); a natural gas stream, said CO ２ introducing the enriched stream (550), the low pressure exhaust gas stream (570) from the second hydrogen PSA unit (560), and the oxygen stream (585) from the air separation unit (580) into a fired heater (590) to produce steam, electricity, or both, and a flue gas stream (605) comprising the carbon dioxide; compressing and drying said flue gas stream (615); The compressed flue gas stream (635) is ２ and recovering the product as a product stream.

10. The method of claim 9, further comprising removing oxygen (620) from the compressed flue gas stream (615) prior to recovering the compressed flue gas stream (635).

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