The present invention relates to the separation of gaseous mixtures. More specifically, the present invention relates to a cyclic pressure swing adsorption (PSA) process to recover an off-gas stream at high pressure with low energy consumption.
Syngas (or synthesis gas) is a gas mixture that contains carbon monoxide CO and hydrogen H2 in various proportions. It generally also contains water, nitrogen, argon, residues of hydrocarbon compounds like CH4, hydrogen sulphide H2S and carbon dioxide CO2. Syngas is traditionally produced by coal gasification, and is useful for basic industrial chemical processes like methanol production and Fischer-Tropsch reaction. It is also useful for producing essentially pure hydrogen. To improve the H2 content, carbon monoxide is preferably converted to carbon dioxide in a water gas shift reaction:
CO+H20→CO2+H2
A water gas shift unit allows maximizing the hydrogen production by the conversion of the most part of the CO.
CO2 and H2S are generally extracted from syngas because they may interact with downstream catalysts and adversely affect downstream syntheses. Different types of processes can be used to remove CO2. Acid gas may be removed from the syngas by means of an acid gas recovery unit. Typically, this type of unit uses a liquid solvent to scrub acid gases like CO2 and H2S. However, the use of a solvent and its subsequent regeneration is expensive. Furthermore, acid gas recovery processes traditionally comprise a step at very low temperature, for instance down to −40° C., which has a high energy cost.
Another type of process which can be used to remove CO2 is the adsorption on a solid phase. Since the early 1980s, pressure swing adsorption (PSA) has become the state of the art technology in the chemical and petrochemical industries for purifying hydrogen. This process is adapted for the continuous production of ultrapure hydrogen gas stream, with a purity of at least 99.99%. The CO2 is recovered in the off-gas of the PSA unit with all the other gases and impurities and with non-separated H2. Consequently, the concentration of CO2 in the off-gas of a PSA is generally low, for example of about 40%.
Different types of PSA processes have been disclosed in the prior art, for example in U.S. Pat. No. 4,512,780, in the U.S. Pat. No. 6,051,050, in the U.S. Pat. No. 5,753,010, in the U.S. Pat. No. 4,171,206, in the European Patent application EP 0 327 732 or in the International Patent Application WO 00/56424. These documents disclose PSA processes with improved functions: quicker, more compact, more flexible, capable of enabling an increased or improved recovery, with improved product yields or with reduced power consumption.
But nowadays, new requirements appear. Due to ecological concern, the reduction of emissions of CO2 has become an important field of research. Carbon dioxide capture and storage constitute a promising option that can drastically reduce these emissions. In this context, it will be advantageous to recover CO2 from syngas treatment plants.
However, the CO2 stream has to meet some criteria in order to be stored. Notably, CO2 concentration is preferably higher than 95% and CO2 stream is typically compressed to the supercritical level for transportation to its storage site. The energetic cost of the compression step is high.
More generally, the off-gas of a PSA process is generally recovered from the PSA unit at a low pressure. However, when this stream is used in downstream units or within the PSA process itself, it may be necessary to compress it until a higher pressure is reached. Compression steps are always energetically demanding.
In this context, it is highly desirable to provide a new improved PSA process to recover an off-gas stream at a high pressure with low energy consumption.
One subject-matter of the present invention is a cyclic PSA process, each cycle of said process comprising a blowdown phase consisting in lowering the pressure in an adsorbent bed from Phigh to Plow, wherein said blowdown phase is divided into several partial blowdown phases, wherein the gas streams discharged during the partial blowdown phases are introduced into respective discharge tanks, wherein the tanks are in fluid communication in series with increasing pressure and a compressor means is located between each connected tank.
Unless otherwise stated, the percentages are volume percentages.
Moreover, the expression “comprised between” should be understood to designate the range described, including the upper and lower bounds.
The PSA process is a well-known technology used to separate some gas species from a mixture of gases with an adsorbent material. At high pressure, specific gas species are preferentially adsorbed on the adsorbent bed. The process then swings to low pressure to desorb said specific gas species from the adsorbent material. Therefore, a PSA process is defined by at least one high pressure Phigh and one low pressure Plow. The values of said high and low pressures are preferably chosen by the skilled person according to the nature of the adsorbent bed and the nature of the gas species to be preferentially adsorbed.
Preferably, the low pressure Plow according to the invention is lower than 5 bar, more preferably lower than 3 bar. Even more preferably, said low pressure Plow is the atmospheric pressure, i.e. 1 atm, which is around 101.325 kPa. The selection of the atmospheric pressure as low pressure is advantageous for the power consumption of the process since it does not require the use of a vacuum pump. The low pressure is preferably not lower than the atmospheric pressure.
The high pressure Phigh of the process according to the present invention is preferably higher than 10 bar, more preferably higher than 30 bar. However, said high pressure generally does not exceed 100 bar.
A PSA process requires the use of at least one adsorbent bed having at least one inlet and one outlet. Adsorbent beds are well-known by the person skilled in the art. Typical adsorbents are activated carbon, silica gel, alumina and zeolites. Examples of such adsorbents are activated carbon PBL from Calgon, activated carbon ACM 3 mm from CECA, activated carbon RB1 or R2030 from Norit, Zeolites 5A from UOP or Linde, Zeolithe 13X from UOP or Süd Chemie, Silica Gel KC from Kali Chemie, Metal Organic Framework MIL 101 or Cu-BTC. An adsorbent bed may consist in one layer or in several layers of different adsorbents. Preferably, the adsorbent bed used in the process according to the present invention consists in one single layer of activated carbon, for example the one marketed by the Norit group under the trade name Activated Carbon R2030.
The PSA cycle of the present invention comprises at least one blowdown phase. The blowdown phase consists in lowering the pressure in the adsorbent bed from Phigh to Plow by withdrawing a gas stream from the adsorbent bed.
It has been discovered that the energetic cost of the process could be significantly reduced by dividing the blowdown phase into several partial blowdown phases, wherein the gas streams discharged during the partial blowdown phases are introduced into respective discharge tanks. This blowdown phase is schematically represented on
On
Tanks T1 to Tn are in fluid communication. Advantageously, the tanks are connected in series with increasing pressure. A compressor means C1 to Cn is located between each connected tank. The gas in each tank, except the tank having the highest pressure, is compressed and introduced into the other tank that has the lowest of the higher pressures. The gas stream at Plow in the tank Tn is compressed and introduced into the tank
Tn-1, which is at a higher pressure, and so on. Finally, the gas stream which is in the tank T1 may be further compressed in the compressor C1. The gas stream at high pressure leaving C1 may for instance be introduced into the adsorbent bed at Phigh for a rinse step for example or may be further compressed to be transported at a supercritical state to a storage site.
Each tank may be equipped with a cooling means, especially a cooling exchanger, E1 to En. Indeed, the lower the temperature of the gas stream, the lower the energy requirement for compressing said gas stream. The cooling means may advantageously contribute to minimize the energetic consumption of the process of the invention.
Preferably, the blowdown pressure decrease condition is linear during each partial blowdown phase. An example of pressure condition for a 360 s blowdown step is represented on
The implementation of the process according to the invention advantageously allows the recovery of an off-gas stream at a high pressure with low energy consumption. As explained above, this process may be implemented to recover CO2 from syngas treatment plants, before the transport of the CO2 stream in a supercritical state to a storage place. In this context, it will be highly desirable that the process according to the present invention allows the recovery of a CO2 stream of a high purity, preferably higher than 95%, with a high recovery yield, preferably higher than 90%.
Classic PSA processes which are well-known in the art do not allow the recovery of CO2 stream of high purity.
According to a preferred embodiment, the process of the present invention is a cyclic PSA process to recover an essentially pure CO2 stream from a feed gas containing H2 and CO2, each cycle of said process consisting of the following consecutive steps:
1. an adsorption phase, which comprises the introduction of said feed gas to the inlet of an adsorbent bed at high pressure Phigh for flowing therethrough with selective adsorption of CO2, forming a first adsorption front of CO2 in said adsorbent bed, and the discharge of an effluent with unadsorbed products from the outlet of said adsorbent bed to a primary discharge tank, said primary discharge tank being under said high pressure Phigh, said adsorption phase being continued for a controlled time period A;
2. a rinse phase, which comprises the introduction of an essentially pure CO2 stream to the inlet of said adsorbent bed at said high pressure Phigh for flowing therethrough, forming a second adsorption front of CO2 in said adsorbent bed, and the discharge of a product effluent from the outlet of said adsorbent bed to said primary discharge tank, said rinse phase being continued for a controlled time period R which ends when said second adsorption front of CO2 joins up the first one and arrives at the outlet of the adsorbent bed;
3. the blowdown phase, as described above, which comprises the lowering of the pressure in said adsorbent bed by countercurrently withdrawing a gas stream therefrom and the discharge of said gas stream through said inlet of said adsorbent bed to secondary discharge tanks, said blowdown phase being continued for a controlled time period B which ends when said adsorbent bed is at low pressure Plow;
4. a countercurrent purge phase, which comprises the introduction of a gas stream coming from said primary discharge tank to the outlet of said adsorbent bed for flowing therethrough, and the discharge of an essentially pure CO2 stream from the inlet of said adsorbent bed to said secondary discharge tank at Plow, said countercurrent purge phase being continued for a controlled time period PU;
5. a pressurization phase, which comprises the introduction of a gas stream coming from said primary discharge tank to the outlet of said adsorbent bed, said pressurization phase being continued for a controlled time period PR which ends when said adsorbent bed is at said high pressure Phigh.
According to the present invention, the expression “essentially pure CO2 stream” means a stream containing at least 90%, preferably at least 95% of CO2.
The feed gas of the process according to this embodiment of the present invention is a gas mixture containing H2 and CO2. Preferably, at least 50%, more preferably at least 60%, more preferably at least 70%, and even more preferably at least 80% of the feed gas is a mixture of H2 and CO2. The proportions of said components may vary. The volume ratio H2/CO2 is preferably between 0.8 and 3, more preferably between 1 and 2.
The feed gas may be produced by a water gas shift process. The source of the feed gas may determine the presence of other compounds than H2 and CO2.
The feed gas may contain one or more other compounds, for instance water, nitrogen, argon, gaseous residues of hydrocarbon compounds like CH4, hydrogen sulphide H2S and carbon monoxide CO. According to a first embodiment, the CO content is at most 10%, preferably at most 5%, more preferably at most 3%, of the feed gas. According to a second embodiment, the CO content is between 10% and 30%, preferably between 20% and 25%, of the feed gas. Preferably, the total content of compounds which are not H2, CO2 and CO is below 10%, more preferably below 5%. It may be advantageous to remove some of the other components, in particular H2O and/or H2S, of the feed gas. H2S and/or H2O removal units are well known in the art and may be implemented before carrying out the process of the present invention.
The feed gas of the process according to this embodiment of the present invention may be at a temperature above −100° C., preferably between 10° C. and 75° C. and more preferably between 20° C. and 60° C. Advantageously, the feed gas does not undergo a cooling step before being introduced into the adsorbent bed. Advantageously, the feed gas is at room temperature.
According to this preferred embodiment, each cycle of the cyclic PSA process consists in five successive phases: 1. Adsorption phase A, 2. Rinse phase R, 3. Blowdown phase B, 4. Countercurrent purge phase PU, and 5. Pressurization phase PR.
A PSA cycle is not continuous. Therefore, traditionally, in an installation that is run continuously with constant feed gas, several adsorbent beds are placed side-by-side for forming a PSA unit. The PSA process according to the preferred embodiment of the present invention is preferably run in a four-bed unit.
A preferred cycle program has been designed for this four-bed embodiment. This cycle program is represented on the chart of
A=R=B=PU+PR
Therefore, the time duration of a full cycle is divided in four equal parts. During each of this part:
According to this cycle program, it is possible to run a four-bed PSA unit according to the preferred embodiment of the process of the present invention continuously.
The five successive phases of one cycle according to the preferred embodiment of the invention are schematically represented on
The adsorption phase comprises the introduction of the feed gas 5 to the inlet 6 of the 1st adsorbent bed 7 at the high pressure Phigh. When the feed gas is flowing through the 1st adsorbent bed 7, CO2 is selectively adsorbed. Unadsorbed product effluent 8 is discharged from the outlet 9 of the 1st adsorbent bed 7 to a primary discharge tank 10. The primary discharge tank 10 is under said high pressure Phigh. The duration of the adsorption phase is designated as A.
The unadsorbed product effluent is substantially free of CO2. Preferably, the CO2 content in the unadsorbed product effluent is below 10%, more preferably below 5%. When CO2 is adsorbed on the adsorbent bed, it forms a first adsorption front. The time period A is controlled in such a way that said first adsorption front of CO2 is still well within the adsorption bed at the end of the step.
At the time the 1st absorbent bed 7 is undergoing the adsorption phase A, the 4th adsorbent bed is undergoing the rinse phase R. An essentially pure CO2 stream 11 is introduced, concurrently to the feed stream, to the inlet 12 of the 4th adsorbent bed 13. The pressure of the pure CO2 stream is the same as the pressure of the feed gas, i.e. said high pressure Phigh. The essentially pure CO2 stream flows through the 4th adsorbent bed 13 and the product effluent 14 is discharged from the outlet 15 of the 4th adsorbent bed 13 to said primary discharge tank 10. The duration of the rinse phase is designated as R.
During said rinse phase, the adsorption of CO2 forms a second adsorption front in the adsorbent bed, which joins the first adsorption front. The time period R and the rinse flow rate are controlled so as to precisely stop when the joined adsorption fronts arrive at the outlet of the adsorbent bed. If the time period R is too long, the joined fronts of CO2 will exceed the adsorbent bed and part of the CO2 will flow to the primary discharge tank with product effluent. The separation of the compound will be poor, and part of CO2 will not be recovered. If the time period R is too short, the joined adsorption fronts of CO2 will not arrive at the outlet of the adsorbent bed. It follows that the adsorbent bed still contains a part of non CO2 product. This will adversely affect the purity of the recovered CO2 stream.
Blowdown Phase B
At the time the 1st absorbent bed 7 is undergoing the adsorption phase A and the 4th adsorbent bed 13 is undergoing the rinse phase R, the 3rd adsorbent bed is undergoing the blowdown phase B. The blowdown phase consists in lowering the pressure in the 3rd adsorbent bed 16 from Phigh to Plow by countercurrently withdrawing a gas stream 12 therefrom and discharging said gas stream through the inlet 17 of the 3rd adsorbent bed 16. The gas stream 18 is discharged into secondary discharge tanks 19, in accordance with the present invention. Said gas stream 18 is essentially pure CO2 stream. The duration of the blowdown phase is designated as B. At the end of the blowdown phase, the pressure of the adsorbent bed has decreased to the low pressure value Plow.
According to the process of the present invention, the blowdown phase is divided into several partial blowdown phases, wherein the gas stream 18 discharged during the partial blowdown phases is introduced into several discharge tanks of decreasing pressure.
At the time the 1st absorbent bed 7 is undergoing the adsorption phase A, the 4th adsorbent bed 13 is undergoing the rinse phase R and the 3rd adsorbent bed 16 is undergoing the blowdown phase B, the 2nd adsorbent bed is undergoing first the countercurrent purge phase PU and then the pressurization phase PR.
Countercurrent Purge Phase PU
The purge phase is implemented countercurrently. A gas stream 20 coming from said primary discharge tank 10 is introduced to the outlet 21 of the 2nd adsorbent bed 22 at the low pressure Plow and is flowing therethrough. It is discharged from the inlet 23 of said 2nd adsorbent bed 22 to said secondary discharge tank 19 at Plow. The duration of the countercurrent purge phase is designated as PU. The countercurrent purge phase and flow rate are controlled so that the bed is essentially free of CO2 at the end of the step.
Pressurization Phase PR
Finally, the last phase of the cycle 4 of the preferred process of the invention is the pressurization phase, which comprises the introduction of a gas stream coming from said primary discharge tank 10 to the outlet 21 of said 2nd adsorbent bed 22. The duration of the pressurization phase is designated as PR. At the end of the pressurization phase, the pressure of the adsorbent bed has increased to the high pressure value Phigh.
The switches from one phase to the other may be achieved by opening and closing of a numbers of switching valves not represented on
The implementation of the preferred embodiment of the process according to the invention advantageously allows the recovery of an essentially pure CO2 gas stream 26 from the feed gas 5. The CO2 recovery yield may reach preferably at least 85%, more preferably at least 90%, and even more preferably at least 95%.
According to a preferred embodiment of the present invention, the essentially pure CO2 stream 11 which is introduced in the adsorbent bed during the rinse phase is provided by the secondary discharge tanks 19. Said stream is compressed into a gas compressor 27 to reach the high pressure value Phigh before being introduced into the adsorbent bed.
According to another preferred embodiment of the present invention, all or part of the essentially pure CO2 stream is evacuated in order to be stored in CO2 storage units. Said stream 26 may be advantageously compressed to a pressure suitable for transportation to its storage site, preferably above the critical pressure.
In order to treat various flow rates of feed gas, several units of PSA may be run in parallel. The feed gas may be divided in the same number of fraction as the number of units. These fractions of feed gas are preferably equal and the several units are preferably identical. The PSA process according to the present invention is preferably run in several four-bed units at the same time. Each of the four-bed units is preferably run according to the cycle program represented on the chart of
The number of partial blowdown phases n is preferably equal to the number of PSA units which are run at the same time. For example, a cyclic PSA process according to the preferred embodiment of the invention wherein the feed gas is divided into n PSA units is preferably run with n blowdown phases, using n secondary discharge tanks. The secondary discharge tanks are preferably shared by all units.
A preferred cycle program, in which n is 6, has been designed to this type of plant. This cycle program is represented on the chart of
According to this cycle program, the time period B is divided in 6 equal partial blowdown phases B1 to B6. The time period PU is equal to the sum of B1 and B2, and the time period PR is equal to the sum of B3, B4, B5 and B6. The cycle program of each unit is shifted from one another for a time period equal to the time of one partial blowdown phase. Thanks to this cycle program, each secondary discharging tank is fed by one column at any time, except for the tank at the lowest pressure Tn which is fed at any time by three columns, two in purge phase and one in blowdown phase B6. According to this preferred cycle program, a relatively flat flow rate is obtained in each secondary discharge tank.
On
The preferred embodiment of the process according to the present invention advantageously allows the recovery of a product effluent which is substantially free of CO2 8 and 14. Said product effluent is recovered into the primary discharge tank 10, which is at the high pressure Phigh of the PSA process. Said product effluent is at least partly used during the countercurrent purge phase and during the pressurization phase. The part remaining in said tank, stream 28, may be used downstream for different uses.
According to a first embodiment of the present invention, the cyclic PSA process as disclosed above is a step of a syngas conditioning chain for a Fischer-Tropsch process. The Fischer-Tropsch process is a well-known chemical process that converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons.
An example of said first embodiment is represented on
According to this embodiment, liquid hydrocarbons 45 may be produced from coal 31 by the global process 30. Coal 31 is introduced into a gasifier reactor 33 with a stream of oxygen 32 to provide syngas 34 containing essentially H2 and CO. Said syngas stream 34 is passed through a water gas shift unit 35 with water 36. The effluent 37 of the water gas shift reactor is subjected to the cyclic PSA process according to the present invention in a PSA plant 41. An essentially pure CO2 stream 42 may be recovered. The product effluent 43, which is essentially free of CO2, is fed to a Fischer-Tropsch reactor 44. The following reactions are catalysed in Fischer-Tropsch reactors:
(2x+1)H2+xCO→CxH(2x+2)+xH2O
where x is a positive integer.
The inlet stream to the Fischer-Tropsch reactor preferably satisfies a stoichiometric ratio of H2/CO between 2.0 and 2.4. Furthermore, the inlet stream preferably contains less than 5% of inert compounds. Therefore, the performance of the PSA process of the invention is adapted by the person skilled in the art to reach these specifications.
Preferably, an H2S removal step may be included in the Fischer-Tropsch process. This step may advantageously take place after the gasification of the coal, before the water gas shift reactor, for removing H2S from the syngas. As represented in
According to a second embodiment of the present invention, the cyclic PSA process as disclosed above is a step of a syngas conditioning chain for a coal to methanol synthesis process.
An example of said second embodiment is represented on
According to this embodiment, a methanol stream 63 may be produced from coal 47 by the global process 46.
According to this embodiment, coal 47 is introduced into a gasifier reactor 49 with a stream of oxygen 48 to provide syngas 50 containing essentially H2 and CO. Said syngas stream 50 is divided into two streams 53 and 54. The first fraction 53 of the stream is mixed with water 55 and is passed through a water gas shift reactor 56. The effluent 57 of the water gas shift reactor is subjected to the cyclic PSA process according to the present invention in a PSA plant 58. An essentially pure CO2 stream 59 may be recovered. The product effluent 60, which is essentially free of CO2, is mixed with the second faction 54 of the syngas stream, and is fed to a methanol reactor 62. In typical methanol reactor the following reactions occur:
CO+2H2→CH3OH
CO2+3H2→CH3OH+H2O
The inlet stream to the methanol reactor 61 preferably satisfies a stoichiometric ratio of (H2—CO2)/(CO+CO2)=2.1. Therefore, the partition of the syngas stream and the performance of the PSA process of the invention are adapted by the person skilled in the art for reaching this stoichiometric ratio.
Preferably, an H2S removal step may be included in the coal to methanol synthesis process. As represented in
A mathematical model with mass, energy and momentum balances that represents the dynamic behaviour of a non isothermal, non diluted, multicomponent adsorbent bed was used to simulate a pressure swing adsorption process. The model was developed based on the following assumptions:
Additionally, the model accounts for external mass and heat transfer resistances, expressed with the film model, and it considers that the adsorbent particles are bidispersed with macropore and micropore mass transfer resistances, both expressed with the Linear Driving Force (LDF) model. The momentum balance is given by the Ergun equation.
The compressor power requirements were calculated considering adiabatic compression, multiple stages with the same pressure ratio and with a 5 psi pressure drop between stages, cooling of the gas between each stage to the inlet temperature of 50° C. and an efficiency of 85%.
A cyclic PSA process with six units, each unit having four beds, has been mathematically modelled. The process cycle was in accordance with the schematic representation of
The adsorbent bed consisted in one single layer of activated carbon marketed by the Norit group under the trade name Activated Carbon R2030.
The other parameters of the PSA process unit are summarized in Table 1.
The feed gas had the following composition:
The power consumption includes the compression of the CO2 to 110 bar for storage. The total power consumption was 181.5 MW, 108.6 MW due to the compression to 65 bar of the stream used in the rinse phase plus 72.9 MW necessary to compress to 110 bar the CO2 product for transportation.
1. b. Process with a Divided Blowdown Phase
The blowdown phase has been divided into six equal partial blowdown phases, in accordance with the schematic representation of
T1: 44.08 bar
T2: 28.04 bar
T3: 16.66 bar
T4: 8.97 bar
T5: 4.14 bar
T6: 1 bar
It has been noted that the compositions of the obtained products and the productivity of the PSA process were not affected by the division of the blowdown phase.
With this configuration, the total energy consumption was only 77.3 MW, including compression for rinse and transportation of CO2.
The two processes 1.a and 1.b allow the recovery of an essentially pure CO2 stream, containing more than 95% CO2. The recovery yield is above 90%.
In the same time, the two processes 1.a and 1.b allow the recovery of a product effluent containing more than 90% H2 and less than 5% CO2. This product effluent may advantageously be mixed with another syngas stream, to be fed to a methanol reactor.
The results obtained with the process 1.a and the process 1.b are compared. The performance of the process was not affected significantly and the recovered CO2 stream and product effluent had comparable specifications. A significant reduction in the power consumption was achieved (over 57%).
A cyclic PSA process with eight units, each unit having four beds, has been mathematically modelled. The process cycle was in accordance with the schematic representation of
The adsorbent bed consisted in one single layer of activated carbon marketed by the Norit group under the trade name Activated Carbon R2030.
The other parameters of the PSA process unit are summarized in Table 3.
The feed gas had the following composition:
The results are summarized in Table 4.
The power consumption includes the compression of the CO2 to 110 bar for storage. The total power consumption was 206.7 MW, 127.9 MW due to the compression to 33 bar of the stream used in the rinse phase plus 78.8 MW necessary to compress to 110 bar the CO2 product for transportation.
2. b. Process with a Divided Blowdown Phase
The blowdown phase has been divided into eight equal partial blowdown phases, in accordance with the schematic representation of
T1: 25.00 bar
T2: 18.60 bar
T3: 13.60 bar
T4: 9.54 bar
T5: 6.42 bar
T6: 4.06 bar
T7: 2.35 bar
T8: 1.00 bar
It has been noted that the compositions of the obtained products and the productivity of the PSA process were not affected by the division of the blowdown phase.
The power consumption obtained was 90.6 MW, including the compression of the CO2 to 110 bar for storage.
The two processes 2.a and 2.b allow the recovery of an essentially pure CO2 stream, containing more than 95% CO2. The recovery yield is above 90%.
In the same time, the two processes 2.a and 2.b allow the recovery of a product effluent containing around 66% H2 and 30% CO. The ratio H2/CO is about 2.2. The content of inert compounds is lower than 5%. This product effluent may advantageously be introduced into a Fischer-Tropsch reactor.
The results obtained with the process 2.a and the process 2.b are compared. The performance of the process was not affected significantly and the recovered CO2 stream and product effluent had comparable specifications. A significant reduction in the power consumption was achieved (over 56%).
Number | Date | Country | Kind |
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11305596.6 | May 2011 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2012/058598 | 5/10/2012 | WO | 00 | 11/18/2013 |