ARSLAN BOZDAG ARZU (TR)
BAYAT AYSEGUL (TR)
DENIZ UTKU (TR)
SEKER BETUL (TR)
WO2015066117A1 | 2015-05-07 |
CN111748366A | 2020-10-09 | |||
CN102351624A | 2012-02-15 |
CLAIMS 1. A system for converting the PSA tail gas stream (4B) released in PSA units (3) into fuel and high value-added chemicals (10B), characterized by comprising: at least one compressor (4) to which the PSA tail gas stream (4B) from said PSA unit (3) is transmitted; at least one heat exchanger (5) to which the output stream of the compressor (5A) is transmitted; a hydrogenation reactor (6) to which the output stream of the heat exchanger (6A) is transmitted; at least one hydrogen source (72) for supplying hydrogen to the hydrogenation reactor (6); at least one condenser (7) to which the reactor output stream (7A) of the hydrogenation reactor (6) is transmitted; at least one carbon dioxide capture unit (8) to which the output stream of the condenser (8A) is transmitted; at least one separation and purification unit (9) to which the output stream of the carbon dioxide capture unit (9B) is transmitted. 2. A system according to claim 1, characterized in that the hydrogenation reactor (6) comprises at least one bifunctional catalyst containing a metal and/or acid catalyst. 3. A system according to claim 1, characterized in that the carbon dioxide capture unit (8) comprises absorption, adsorption, membrane technologies and/or hybrid combinations thereof. 4. A method for converting the PSA tail gas stream (4B) released in PSA units (3) into fuel and high value-added chemicals (10B), characterized by comprising the steps of: transmitting at least one part of the PSA tail gas stream (4B) from the PSA unit (3) to at least one compressor (4); pressurizing the PSA tail gas (4B) in the compressor (4); transmitting output stream of the compressor (5A) to at least one heat exchanger (5) so that the output stream is brought into a reaction operating temperature in the range of 200-600 °C; feeding the output stream of the heat exchanger (6A) to the hydrogenation reactor (6); feeding additional hydrogen from at least one hydrogen source (72) to the hydrogenation reactor (6); transmitting the output stream of the reactor (7A) obtained from the hydrogenation reactor (6) to at least one condenser (7); applying heat treatment to the output stream of the reactor (7A) in said condenser (7); feeding the output stream of the condenser (8A) to the carbon dioxide capture unit (8); transmitting the output stream of the carbon dioxide capture unit (9B) to at least one separation and purification unit (9); and obtaining fuel and high value-added chemicals (10B) from the separation and purification unit (9). 5. A method according to claim 4, characterized in that the pressure value of the PSA tail gas stream (4B) is brought to the range of 5-50 bar in said compressor (4). 6. A method according to claim 4, characterized in that the heat treatment applied in the condenser (7) is a cooling process. 7. A method according to claim 4, characterized in that absorption, adsorption, membrane technologies and/or hybrid combinations thereof are used in the carbon dioxide capture unit (8). 8. A method according to claim 4, characterized in that the output stream of the heat exchanger (6A) transmitted to the hydrogenation reactor (6) contains H2:C02 with a molar ratio in the range of 3: 1 - 10: 1. 9. A method according to claim 4, characterized in that the output stream of the heat exchanger (6A) transmitted to the hydrogenation reactor (6) contains C02:C0 with a molar ratio in the range of 4: 1 - 15: 1. |
Technical Field
The present invention relates to a system and a method for obtaining fuel and high value- added chemicals by utilizing the components in the tail gas stream in PSA units.
Backqround of the Invention
Since cracking and desulphurization demands increase day by day in refineries and petrochemical plants, the need for hydrogen gas reacted in these processes increases and hydrogen production units gain importance. Refineries are energy-intensive industries and consume large amounts of petroleum-derived fuels and natural gas for the continuity of the processes. In hydrogen production units, hydrogen gas is produced by using a catalytic steam-methane reformer unit, a water-gas shift converter and a pressure swing adsorption (PSA) unit. While high purity hydrogen gas is produced in said PSA units, PSA tail gas is also formed as a side stream. Typically, 65-70% of the hydrogen produced in refineries is produced in steam-methane reformer units and PSA units. PSA tail gas (with a carbon dioxide content of approximately 40-60% by volume) is a carbon dioxide-rich process gas. PSA tail gas also comprises hydrogen, methane, carbon monoxide and nitrogen. Thanks to its high synthesis gas (C0 2 , CO, H 2 ) content, without containing pollutants such as hydrogen sulfide (H 2 S), sulfuroxide (SO x ), nitrogen oxide (NO x ), halogen and particulates, the PSA tail gas is an ideal gas stream for the utilization of carbon dioxide and conversion processes. The conversion of natural gas to hydrogen in the steam-methane reformer units creates a PSA tail gas stream. The PSA tail gas, which is very rich in content, constitutes approximately 20-30% of carbon dioxide emissions in refineries due to the high amount of carbon dioxide it contains. Following the reactions and hydrogen purification processes in hydrogen production units, approximately 5 tons of carbon dioxide is released for 1 ton of hydrogen production, and the amount of emissions reaches the order of 10 tons together with the energy and auxiliary service needs used in the processes. Being the primary greenhouse gas, carbon dioxide accumulates in the atmosphere to form a heat-reflecting layer and causes an increase in the atmospheric temperature. Carbon dioxide, which accounts for approximately 76% of total greenhouse gas emissions, is released as a result of the combustion of coal, petroleum-derived fuels, natural gas and other carbon-based fuels, and carbon dioxide emissions are increasing rapidly on a global scale. There is a need to mitigate or eliminate the effects of carbon dioxide, which is one of the biggest factors of climate change and global warming, by means of processes for the conversion of carbon dioxide with innovative technological solutions.
Brief Description of the Invention
The present invention discloses a system for converting the PSA tail gas stream released in PSA units into fuel and high value-added chemicals, the system comprising: at least one PSA unit for producing high purity hydrogen; at least one compressor to which all or part of the PSA tail gas stream from said PSA unit is transmitted; at least one heat exchanger to which the output stream of the compressor is transmitted; a hydrogenation reactor to which the output stream of the heat exchanger is transmitted; at least one condenser to which the reactor output stream of the hydrogenation reactor is transmitted; at least one carbon dioxide capture unit to which the output stream of the condenser is transmitted; at least one separation and purification unit to which the output stream of the carbon dioxide capture unit is transmitted; and at least one hydrogen source.
The present invention also provides a method for converting the PSA tail gas stream into fuel and high value-added chemicals. The method comprises the steps of: transmitting all or part of the PSA tail gas stream from the PSA unit to at least one compressor; pressurizing all or part of the PSA tail gas in at least one compressor; transmitting output stream of the compressor to at least one heat exchanger so that the output stream is brought into a reaction operating temperature in the range of 200-600 °C; feeding the output stream of the heat exchanger to the hydrogenation reactor; feeding additional hydrogen to the hydrogenation reactor, wherein the additional hydrogen is supplied from at least one hydrogen source and brought to the desired conditions; transmitting the output stream of the reactor obtained from the hydrogenation reactor to at least one condenser; applying heat treatment to the output stream of the reactor in said condenser; feeding the output stream of the condenser to the carbon dioxide capture unit; and transmitting the output stream of the carbon dioxide capture unit to at least one product separation column.
The present invention provides a system and a method for the production of fuel and high value-added chemicals by capturing carbon dioxide in process gases. The PSA tail gas (4B) and additional external hydrogen gas are supplied to the hydrogenation reactor (6) to obtain fuel and high value-added chemicals (10B). With the invention, the carbon emission effect of carbon dioxide on refinery processes is alleviated. The present invention allows conversion of waste carbon dioxide gas, which is released as a by product in large quantities, into fuel and high value-added chemicals such as methanol, formic acid, formaldehyde, dimethyl ether, ethanol, ethylene, propane, propylene, olefins with higher carbon atoms, and hydrocarbons. According to the system and method of the invention, process waste carbon dioxide gas without a fuel value is converted into high value-added products such as hydrocarbons compatible with the mentioned fuel and chemicals group, by means of catalytic processes in a sustainable and eco-friendly manner. Thanks to the invention, the circular economy is improved, as well as reducing the carbon footprint.
Object of the Invention
An object of the present invention is to provide a system and a method for the production of fuel and high value-added chemicals in a single reactor from carbon dioxide-rich process gas streams.
Another object of the present invention is to provide a system and a method for converting the PSA tail gas stream released in the PSA unit into high value-added products by catalytic processes.
A further object of the present invention is to provide a system and a method for converting the process waste carbon dioxide gas without a fuel value into high value- added products through catalytic processes in a sustainable and eco-friendly manner. Yet another object of the present invention is to provide a system and a method for producing fuel and high value-added chemicals from the PSA tail gas stream by addition of hydrogen gas.
Description of the Drawings
An exemplary system according to the present invention is illustrated in the attached drawings, in which:
Figure 1 is a schematic diagram of the system according to the invention.
All the parts illustrated in figures are individually assigned a reference numeral and the corresponding terms of these numbers are listed below:
First gas stream (1A)
Steam (1B)
Steam-methane reformer unit (1)
Reformer output stream (2A)
Water-gas shift converter (2)
Output stream of the converter (3A)
PSA unit (3)
Hydrogen gas stream (4A)
PSA tail gas stream (4B)
Recycled tail gas stream (4C)
Compressor (4)
Output stream of the compressor (5A)
Heat exchanger (5)
Output stream of the heat exchanger (6A)
Hydrogenation reactor (6)
Output stream of the reactor (7A)
Second gas stream (71)
Hydrogen source (72)
Condenser (7)
Output stream of the condenser (8A) Carbon dioxide capture unit (8) Third gas stream (9A)
Output stream of the carbon dioxide capture unit (9B)
Separation and purification unit (9) Fourth gas stream (10A)
Fuel and high value-added chemicals (10B)
Description of the Invention
Oil refineries, cement production facilities, power generation facilities, iron and steel industry and petrochemical plants are the major industrial sources of carbon dioxide emissions. Carbon dioxide emissions from the refinery sector constitute 4% of global emissions. One of the units causing most of the carbon dioxide emission throughout the refinery is the hydrogen production unit, which is based on the steam-methane reformer process and operated to meet the hydrogen requirement of the refinery. In the hydrogen production units, the mixture of methane, hydrogen, carbon monoxide and carbon dioxide gases contained in the output stream of the water-gas shift converter and the steam are sent to the condensers, where the steam is separated from said gas mixture. The remaining gas mixture is sent to PSA units for separation or purification of hydrogen gas. Tail gas from the PSA units contains high amount of carbon dioxide by volume. Tail gas from the PSA units is returned to the system and is generally used as fuel in the steam- methane reformer furnace, or converted into fuel and chemicals in systems containing at least two serial reactors. Various technologies are available at different scales and at different stages of development to capture the carbon dioxide contained in PSA tail gas and similar process gases; however, no effective solution has been found for the effective and energy efficient disposal of the captured carbon dioxide. Further, according to the studies carried out within the scope of carbon dioxide conversion, low carbon dioxide conversion is observed, especially since carbon dioxide hydrogenation is a reaction limited by thermodynamic equilibrium and carbon dioxide is a very stable compound. Reactions of carbon dioxide and carbon monoxide gases with hydrogen gas (also called hydrogenation reaction) are highly exothermic equilibrium reactions. Unreacted carbon dioxide gas in the output stream of the hydrogenation reactor is tried to be separated using different capture technologies such as adsorption, absorption or membrane technologies. However, due to the high costs of carbon dioxide capture, the use of energy-intensive processes, and the importance of geology in carbon dioxide storage, difficulties such as site suitability reveal carbon dioxide conversion as a rapidly developing research area for sustainable fuel and chemical production. The use of carbon dioxide as a carbon source and its conversion into high value-added fuels and chemicals are a necessity to complete the carbon cycle. However, in current applications, the conversion of synthesis gas (carbon dioxide, carbon monoxide and hydrogen gases) to fuel and chemicals is carried out in two series reactors. Therefore, there is a need for a system to convert synthesis gas, which can be exemplified as PSA tail gas, directly into fuel and high value-added chemicals by using a single reactor, in order to reduce the energy need, increase the conversion and thus the efficiency. The present invention provides a system and a method for producing fuel and high value-added chemicals from PSA tail gas streams with a single reactor. Thanks to the present invention, fuels and high value-added chemicals such as methanol, formic acid, formaldehyde, dimethyl ether, ethanol, ethylene, propane, propylene, olefins with higher carbon atoms, and hydrocarbons are produced in a single hydrogenation reactor.
The system according to the present invention, as illustrated in Figure 1, comprises at least one PSA unit (3) for purifying the hydrogen; at least one compressor (4) to which the PSA tail gas stream (4B) from said PSA unit (3) is transmitted; at least one heat exchanger (5) to which the output stream of the compressor (5A) is transmitted; a hydrogenation reactor (6) to which the output stream of the heat exchanger (6A) is transmitted (in particular, preferably a single hydrogenation reactor (6) is used); at least one condenser (7) to which the output stream of the hydrogenation reactor (7A) is transmitted; at least one carbon dioxide capture unit (8) to which the output stream of the condenser (8A) is transmitted; at least one separation and purification unit (9) to which the output stream of the carbon dioxide capture unit (9B) is transmitted; and at least one hydrogen source (72) for supplying hydrogen to the hydrogenation reactor (6). According to the system disclosed, the hydrogen source (72) is preferably provided by a green/renewable hydrogen source, a refinery hydrogen ring line, a hydrogen storage tank, a second gas stream (71) provided by the hydrogen gas stream (4A) coming out of the PSA unit (3) and/or combinations thereof. The PSA unit (3) according to the invention is also known in the art as a pressure swing adsorption unit or a hydrogen production unit. The separation and purification unit (9) in the system according to the present invention preferably comprises a series of separation columns including a distillation column, a separator column, a fractionation column, a liquid-gas separator, a splitter and/or combinations thereof. In the described system, the number of columns in the separation and purification unit (9) varies depending on the final product targeted. For example, in the system according to the invention, the preferred number of columns varies between 1 and 10. Depending on the final product targeted in the system according to the invention, the separation methods used in the separation and purification unit (9) vary. For example, a partitioned distillation column process is applied to obtain methanol as a final product; a distillation process is applied for separation of hydrocarbon products; a separator process is applied for separating products of hydrotreating, reverse water-gas shift, oligomerization and olefin reactions; and a fractionation process is applied to separate liquid hydrocarbons. Thanks to the invention, a higher synthesis gas conversion, molar intermediate product equivalent productivity, product selectivity and product yield are achieved in the production.
According to the PSA unit (3) disclosed in the invention, hydrogen is purified such that hydrogen gas is obtained with a purity of approximately 99.5% and more by volume. The PSA unit (3) has two outputs. The first output of the PSA unit (3) is a hydrogen gas stream (4A) and contains the high purity hydrogen gas. The PSA tail gas stream (4B), which is the second output of the PSA unit (3), contains approximately 40% to 60% carbon dioxide by volume, as well as hydrogen, methane, carbon monoxide and nitrogen gases. The tail gas stream (4B), which contains a gas mixture rich in carbon dioxide, is a suitable gas stream for carbon dioxide utilization and conversion since it does not contain pollutants such as hydrogen sulfide (H 2 S), sulfur oxide (SO x ), nitrogen oxide (NO x ), halogen and particulates. The PSA tail gas stream (4B) accounts for approximately 20-30% of refinery emissions due to the high amount of carbon dioxide it contains. With the invention, the PSA tail gas stream (4B), which causes high carbon dioxide emissions, is utilized.
In a preferred embodiment of the system according to the invention, all of the PSA tail gas stream (4B) coming out of the PSA unit (3) is used for the production of fuel and high value-added chemicals. Alternatively, some of the PSA tail gas stream (4B) is fed back to a steam-methane reformer unit (1). The recycled tail gas stream (4C), which is fed back to the steam-methane reformer unit (1), is used as fuel in the furnaces located in the steam- methane reformer unit (1). In this way, it provides both the recycling of waste carbon dioxide, which is released in significant amounts, into high value-added fuels and chemicals, and the production of clean and eco-friendly products by encouraging the use of renewable resources. The remaining PSA tail gas stream (4B) after the feedback is transmitted to at least one compressor (4) to be pressurized since it will be used for conversion to fuel and high value-added chemicals. Preferably, a major part of the PSA tail gas stream (4B), which has high carbon dioxide emissions, is used for fuel and high value-added chemical conversion. Thanks to the present invention, approximately 20-30% of the carbon dioxide emissions in the refinery are handled by means of the system according to the invention.
In a preferred embodiment of the present invention, said hydrogenation reactor (6) comprises bifunctional catalysts containing a metal catalyst and/or an acid catalyst. The type of catalyst may vary according to the desired final product. Thanks to the invention, fuel and high value-added chemicals such as methanol, formic acid, formaldehyde, dimethyl ether, ethanol, ethylene, propane, propylene, olefins with higher carbon atoms, and hydrocarbons are produced in a single reactor by using bifunctional catalysts containing a metal catalyst and/or an acid catalyst. In the hydrogenation reactor (6) disclosed by the invention, catalysts with high catalytic activity are used for the conversion of carbon dioxide. Said catalysts preferably comprise copper, cobalt, palladium, rhenium, nickel, iron, ruthenium, platinum, iridium, silver, rhodium and gold-based metal catalysts and/or combinations thereof. Said catalysts are preferably supported by catalyst support materials comprising transition metal silicates, aluminates, titanates and/or combinations thereof, thereby increasing the catalytic performance capacity of the metal. In addition to the mentioned metal catalysts, the hydrogenation reactor (6) preferably comprises solid acid catalysts such as aluminas, zeolites, heteropoly acids, depending on the product to be produced.
In a preferred embodiment of the invention, the hydrogenation reactor (6) is preferably exemplified as a multiple plug flow reactor, a fixed bed reactor, a reactor containing catalyst beds in which gas is re-distributed among the stages, or a multi-tubular fixed bed reactor. Using the single-reactor system proposed in the invention instead of two reactors increases the PSA tail gas conversion by turning the thermodynamic equilibrium in favour of the products, and also reduces the total energy consumption by eliminating the need for the use of the second reactor. Increasing the PSA tail gas conversion using a single reactor significantly increases yield. The use of a single reactor increases the final product selectivity and product yield by preventing the formation of intermediate products that will occur in the use of two reactors.
The system according to the invention preferably comprises at least one steam-methane reformer unit (1). In the steam-methane reformer unit (1), a pre-treated first gas stream (1A) is combined with steam (1B) at high temperatures in the catalytic process to produce the hydrogen. Since the amount of hydrogen obtained in the steam-methane reformer unit (1) is not high, the amount of hydrogen contained in the reformer output stream (2A) is low. Therefore, the developed system preferably comprises at least one water-gas shift converter (2). Since the amount of hydrogen produced in the water-gas shift converter (2) is increased, there would be a higher proportion of hydrogen in the output stream of the converter (3A) compared to the reformer output stream (2A). The output current of the converter (3A) is fed to the PSA unit (3) to obtain high purity hydrogen. In addition, the source from which the first gas stream (1 A) described within the scope of the invention is provided is preferably a natural gas, methane and/or naphtha source. The method according to the invention comprises the steps of: transmitting all or part of the PSA tail gas stream (4B) from the PSA (3) unit to at least one compressor (4); bringing the PSA tail gas stream (4B) to suitable pressures (preferably in the range of 5-50 bar, more preferably in the range of 30-45 bar) in at least one compressor (4); transmitting output stream of the compressor (5A) to at least one heat exchanger (5) so that the output stream is brought into suitable temperatures (preferably in the range of 200-600 °C, more preferably in the range of 250-400 °C); transmitting the output stream of the heat exchanger (6A) to the hydrogenation reactor (6) (here, the hydrogenation reactor (6) preferably contains metal catalyst and/or acid catalysts); feeding additional hydrogen from at least one hydrogen source (72) to the hydrogenation reactor (6); transmitting the output stream of the reactor (7A) obtained from the hydrogenation reactor (6) to at least one condenser (7); applying heat treatment (preferably, cooling) to the output stream of the reactor (7A) in said condenser (7); feeding the output stream of the condenser (8A) to the carbon dioxide capture unit (8); and transmitting the output stream of the carbon dioxide capture unit (9B) to the separation and purification unit (9). According to the method according of present invention, the carbon dioxide gas unreacted in the hydrogenation reactor (6) is separated in the carbon dioxide capture unit (8). Therefore, said carbon dioxide capture unit (8) has at least two outputs. One of these outputs comprises a third gas stream (9A) containing carbon dioxide gas unreacted in the hydrogenation reactor (6). Said third gas stream (9A) is fed back to the hydrogenation reactor (6). The other output is the output stream of the carbon dioxide capture unit (9B), which is free of carbon dioxide. As mentioned above, unreacted carbon dioxide gas is separated in the carbon dioxide capture unit (8). For this separation process, methods using carbon dioxide capture technologies including adsorption, absorption, membrane and/or combinations thereof (preferably absorption) are applied. The carbon dioxide capture unit (8) of the invention preferably comprises two different capture technologies.
In an exemplary embodiment of the invention, a first gas stream (1A) and steam (1B) provided from at least one source are fed to the steam-methane reformer unit (1). The reformer output stream (2A) is transmitted to the water-gas shift converter (2). The output stream of the converter (3A) is transmitted to the PSA unit (3). The first output of the PSA unit (3) is the hydrogen gas stream (4A), and it contains high purity hydrogen gas (over 99.5% by volume). The second output of the PSA unit (3) is the PSA tail gas stream (4B), and it contains carbon dioxide at a rate of about 40-60% by volume, as well as hydrogen, methane, carbon monoxide and nitrogen gases. Thanks to its high carbon dioxide content, without containing pollutants such as hydrogen sulfide (H 2 S), sulfur oxide (SO x ), nitrogen oxide (NO c ), halogen and particulates, the PSA tail gas (4B) is a suitable gas stream for carbon dioxide utilization and conversion. All or part of the PSA tail gas stream (4B) is transmitted to at least one compressor (4) and subjected to pressurization. The PSA tail gas stream (4B) contains approximately 40-60% carbon dioxide, 24-33% hydrogen, 4-9% carbon monoxide, 11-19% methane and 1-2% nitrogen by volume. More than 75% by volume of the PSA tail gas stream (4B) consists of synthesis gas. In case a part of the PSA tail gas stream (4B) is transmitted to the compressor (4), the remaining recycled tail gas stream (4C) is preferably fed to the steam-methane reformer unit (1). In addition, the source from which the first gas stream (1A) of the invention is provided is preferably a natural gas, methane and/or naphtha source.
In another preferred embodiment of the method according to the present invention, additional hydrogen is fed to the hydrogenation reactor (6) from at least one hydrogen source (72). The hydrogen source (72) is preferably provided by a green/renewable hydrogen source, a refinery hydrogen ring line, a hydrogen storage tank, a hydrogen gas stream coming out of the PSA unit (3) and/or combinations thereof (more preferably, a green/renewable hydrogen source). Said renewable hydrogen source is preferably wind energy, solar energy and/or a source that produces hydrogen by the electrolysis process of water with a minimum capacity of 175 MW. According to the method disclosed in the invention, the amount of hydrogen contained in the PSA tail gas stream (4B) is not sufficient for the successful execution of the hydrogenation reaction and the production of the targeted hydrocarbons due to the low stoichiometry. Therefore, an appropriate amount of additional hydrogen feeding is required. For this purpose, in the method according to the invention, the mole ratio of H 2 :C0 2 is preferably 3:1 - 10:1 at the entrance of the hydrogenation reactor (6). While determining this ratio, the molar ratio of H 2 :C0 2 contained in the hydrogen stream coming from at least one hydrogen source (72) feeding to the hydrogenation reactor (6) and the output stream of the heat exchanger (6A) fed to the hydrogenation reactor (6) is taken into account.
In an alternative embodiment of the method according to the present invention, all or part of the PSA tail gas stream (4B) is brought to the operating conditions required for the reaction by means of at least one compressor (4) and at least one heat exchanger (5), respectively. For this purpose, the PSA tail gas stream (4B) is pressurized in at least one compressor (4) and preferably brought to pressure values in the range of 5-10 bar. During the gas compression processes in the compressor (4), the temperature of the fluid increases. Hot fluids entering the compressor (4) cause the compressor (4) to overheat. For this reason, a gradual cooling process is preferably applied in the compressor (4) according to the invention. The output stream of the compressor (5A) is then transmitted to the heat exchanger (5), and its temperature is adjusted in accordance with the reaction temperature, and then the output current of the heat exchanger (6A) is fed to the hydrogenation reactor (6). The pressurized PSA tail gas stream (4B) is fed to the heat exchanger (5) as the output stream of the compressor (5A). The output stream of the compressor (5A) is brought to the operating temperatures required for the reaction (preferably in the range of 200-600 °C) in the heat exchanger (5).
In an embodiment of the method according to the present invention, the output stream of the reactor (7A) is preferably transmitted to at least one condenser (7). In the condenser (7), water vapor and/or liquid by-products, which are contained in the output stream of the reactor (7A) and released as by-products in the reactions, are removed by condensation. The output stream of the condenser (8A) free from water vapor is passed through the carbon dioxide capture unit (8). In the carbon dioxide capture unit (8), the third gas stream (9A) containing unreacted carbon dioxide gas is separated. In the carbon dioxide capture unit (8), adsorption, absorption, membrane technologies and/or technologies including combinations thereof are used as the separation process. In said separation process, preferably absorption technology, more preferably dual hybrid carbon dioxide capture combinations of these technologies are used. Examples of the dual hybrid carbon dioxide capture combinations described here are adsorption-membrane technologies or absorption-membrane technologies. In the method developed with the invention, the third gas stream (9A) separated in the carbon dioxide capture unit (8) is preferably fed back to the hydrogenation rector (6). Another output of the carbon dioxide capture unit (8) is the output stream of the carbon dioxide capture unit (9B), which is purified from carbon dioxide. The output stream of the carbon dioxide capture unit (9B) is preferably passed through a series of separation columns for the production of fuel and high value-added chemicals (10B).
The separation and purification unit (9) in the system according to the present invention preferably comprises a series of separation columns including a distillation column, a separator column, a fractionation column, a liquid-gas separator, a splitter and/or combinations thereof. In the described system, the number of columns in the separation and purification unit (9) and the separation methods vary depending on the final product targeted. The separation and purification unit (9) preferably comprises 1 to 10 columns. The separation and purification unit (9) has two outputs. One of them contains fuel and high value-added chemicals (10B). The other is the fourth gas stream (10A) obtained after the separation processes are carried out. The fourth gas stream (10A) contains methane, carbon monoxide and hydrogen gases and is preferably fed back to the water-gas shift converter (2).
In the method disclosed by the invention, preferably, the volume ratios of the components in the PSA tail gas stream (4B) are regulated. The PSA tail gas stream (4B) coming out of the PSA units (3), which has a daily flow rate of approximately 300 - 1,800 tons, contains C0 2 , H 2 and CO components. The ratio of C0 2 :CO contained in the PSA tail gas stream (4B) is preferably 4:1 - 15:1 by volume. The ratio of H 2 :C0 2 contained in the PSA tail gas stream (4B) is preferably in the range of 0.4:1 - 1.0:1 by volume. The ratio of H 2 :C0 2 contained in the PSA tail gas stream (4B) is preferably 11:1 by volume. These ratios are valid even if all or part of the PSA tail gas stream (4B) is used. Since the treatments applied to the PSA tail gas stream (4B) in the compressor (4) and the heat exchanger (5) are related to the reaction operating conditions, the above ratios for the PSA tail gas stream (4B) are the same for the output stream of the compressor (5A) and the output stream of the heat exchanger (6A).
In another embodiment of the invention, preferably, the volume ratios of the components in the reformer output stream (2A) are regulated. The ratio of C0 2 :CO contained in the reformer output stream (2A) is preferably in the range of 0.4:1 - 1.0:1 by volume. The ratio of H 2 :C0 2 contained in the reformer output stream (2A) is preferably in the range of 6:1 - 20:1 by volume. The ratio of H 2 :CO contained in the reformer output stream (2A) is preferably 4:1 - 9:1 by volume. In addition, the volume ratios of the components in the output stream of the converter (3A) are preferably regulated. The ratio of C0 2 :CO contained in the output stream of the converter (3A) is preferably in the range of 4:1 - 14:1 by volume. The ratio of H 2 :C0 2 contained in the output stream of the converter (3A) is preferably in the range of 1:1 to 9:1 by volume. The ratio of H 2 :CO contained in the output stream of the converter (3A) is preferably in the range of 28:1 - 80:1 by volume.
The present invention provides a system and a method for the production of fuel and high value-added chemicals by capturing carbon dioxide in process gases. The PSA tail gas (4B) and additional external hydrogen gas are supplied to the hydrogenation reactor (6) to obtain fuel and high value-added chemicals (10B). With the invention, the carbon emission effect of carbon dioxide on refinery processes is alleviated. The present invention allows conversion of waste carbon dioxide gas, which is released as a by product in large quantities, into fuel and high value-added chemicals such as methanol, formic acid, formaldehyde, dimethyl ether, ethanol, ethylene, propane, propylene, olefins with higher carbon atoms, and hydrocarbons. According to the system and method of the invention, process waste carbon dioxide gas without a fuel value is converted into high value-added products such as hydrocarbons compatible with the mentioned fuel and chemicals group, by means of catalytic processes in a sustainable and eco-friendly manner. Thanks to the invention, the circular economy is improved, as well as reducing the carbon footprint.