Filtration unit of amine solution in the ammonia production system

Abstract

FIELD: chemical production.SUBSTANCE: invention relates to amine purification of a gas stream comprising acid gas and can be used in process flows for the production of ammonia, methanol, and urea. The filtration unit located on the line of the deeply regenerated amine solution entering from the regenerator into the absorber comprises at least one injection pump and at least two filters. The first filter, located upstream of the second filter, is a carbon filter, wherein the amine solution is fed into the carbon filter at the discharge pressure of the injection pump, wherein the pump discharge pressure is lower than or equal to the pressure in the filtration chamber of the carbon filter, and wherein the amine solution is fed into the carbon filter in a multi-jet manner.EFFECT: increase in filtration efficiency, ensuring reliable purification of the amine solution, with the ability to prevent foaming of the regenerated solution, efficient operation of the carbon filter in the amine gas flow purification system and, thus, ensuring uninterrupted operation of the ammonia production system.14 cl, 5 dwg, 1 tbl, 1 ex

Description

[0001] FIELD OF TECHNOLOGY

[0002] The invention relates to amine purification of a gas stream containing acid gas and can be used in process flow charts for the production of ammonia, methanol, and urea.

[0003] STATE OF THE ART

[0004] Amine scrubbing of converted gas in ammonia production has a number of specific features due to the composition of the gas mixture, product purity requirements, and process conditions. Unlike oil refining (where the primary objective is hydrogen sulfide removal), the primary objective in ammonia production is the selective removal of carbon dioxide. Hydrogen sulfide is removed from converted gas for ammonia production at earlier stages of desulfurization, but amine scrubbing of carbon dioxide is necessary in this case because CO2 poisons the ammonia synthesis catalyst and disrupts the stoichiometric H2:N2 ratio.

[0005] To maximize the absorption of CO2 in the purification of convertible gas in ammonia production, CO2 absorption is carried out at elevated pressure (2-4 MPa) and reduced temperature (45-60°C), and the regeneration of the amine solution is carried out at reduced pressure and elevated temperature to separate CO2 from the saturated, rich solution.

[0006] Ethanolamine solutions used to purify gases from acidic components are prone to foaming, which poses a serious problem during the operation of gas purification systems. At critical concentrations of undesirable substances in the amine solution, such as resin-like substances, formic acid, and heat-stable salts, the solution ceases to function properly, as essentially its entire volume transforms into foam, filling the system's equipment. At this point, the sensors detect a maximum level in the equipment, triggering a level lockout and shutting down production.

[0007] In the prior art, the foaming problem is solved by introducing antifoaming additives and filtering the amine solution.

[0008] For example, in Russian Patent No. 2839466, to remove amine degradation products that lead to equipment corrosion and foaming, the crudely regenerated aqueous amine solution exiting the regenerator, either fully or partially, is filtered. As follows from the following source, placing the filter in the crudely regenerated solution line has its drawbacks.

[0009] According to the work of E.S. Goryainova, "Modernization of the system for cleaning converted gas from carbon dioxide in the production of ammonia using the example of PJSC Togliattiazot", bachelor's thesis, Togliatti 2019 - pp. 28-34, the ammonia production unit also contains a filtration unit for an amine solution, located on the line of roughly regenerated solution. The filtration unit contains 6 filters - two mechanical, then two carbon, and after them - two more mechanical. Problems associated with the use of carbon filters have been identified: when using carbon filters, the concentration of piperazine in the system decreases below the standard of the process regulations; the MDEA solution contains a high amount of corrosive substances; carbon filters do not sorb pollutants. Due to the above reasons, the carbon filters were disabled and are currently not functioning.

[0010] From the article by B.E. Shermatov et al. Pilot-industrial setup for determining the activity of sorbents in the purification and clarification of regenerated amine solution / / Universum: chemistry and biology. - 2020. - No. 7 (73). - P. 90-94., it is known that despite the fact that various microporous sorbents silica gel, natural and synthetic zeolites, alumina gels, porous glasses, ion exchangers can be used for the separation and purification of gases, recovery of volatile organic solvents and clarification of amine solutions, only activated carbons fully meet the requirements for a solid absorber, i.e. they have high sorption capacity and selectivity, high mechanical strength and regeneration capacity, as well as low cost.

[0011] Therefore, there is a need in the art for a reliable amine purification system for ammonia production gas using a carbon filter for the amine solution. The objective of the present invention is to provide a reliable amine solution purification system capable of preventing foaming of the regenerated solution, ensuring the efficient operation of the carbon filter in the amine gas purification system, and thus ensuring the efficient and uninterrupted operation of the ammonia production system.

[0012] SUMMARY OF THE INVENTION

[0013] A filtration unit is proposed, located on the line of a deeply regenerated amine solution coming from a regenerator to an absorber, wherein the unit contains at least one injection pump and at least two filters, wherein the first filter, located upstream from the second filter, is a carbon filter, wherein the amine solution is fed into the carbon filter at the injection pressure of the injection pump, wherein the pump injection pressure value is lower than or equal to the pressure value in the filtration chamber of the carbon filter, wherein the amine solution is fed into the carbon filter in a multi-jet manner.

[0014] In a preferred embodiment of the invention, the unit is configured to maintain the pressure in the filtration chamber of the carbon filter at 0.5-2.5 MPa, preferably at 0.7-1.7 MPa, even more preferably at 1-1.5 MPa higher than the pressure in the absorber located downstream of the filtration unit.

[0015] In a preferred embodiment of the invention, the unit is configured to maintain a pressure in the filter filtration chamber of 2.9 to 5.3 MPa, preferably 3.2 to 4.5 MPa, even more preferably 3.5 to 3.8 MPa.

[0016] In a preferred embodiment of the invention, the discharge pressure of the injection pump is from 2.9 to 3.8 MPa.

[0017] In a preferred embodiment of the invention, the jets of amine solution are directed upward or upward and sideways.

[0018] In a preferred embodiment of the invention, the carbon filter comprises a filter medium comprising one or more of the following: activated charcoal, hard coal, or anthracite. In a particular case, activated birch carbon with a particle size of 1-4 mm is used.

[0019] In a preferred embodiment of the invention, the carbon filter functions as a pressure vessel.

[0020] In a preferred embodiment of the invention, the assembly comprises a shut-off valve installed at the outlet of the carbon filter and configured to remain in the closed position until a predetermined pressure in the carbon filter is reached. In a preferred embodiment of the invention, the shut-off valve is configured to regulate the flow rate of the amine solution from the carbon filter. In a preferred embodiment of the invention, the first and second filters are configured to operate separately.

[0021] In a preferred embodiment of the invention, the amine solution is a deeply regenerated aqueous solution of activated methyldiethanolamine with a concentration of 30-50%.

[0022] In a preferred embodiment of the invention, the second filter is a cartridge filter located downstream of the carbon filter. In a preferred embodiment, the cartridge filter comprises a replaceable cartridge made of polypropylene.

[0023] BRIEF DESCRIPTION OF FIGURES

[0024] Fig. 1 - schematic representation of the stages of the process of obtaining converted gas for ammonia synthesis

[0025] Fig. 2 - diagram of the absorption unit for cleaning the converted gas with an ethanolamine solution

[0026] Fig. 3 - sectional view of the upper part of the carbon filter housing with a distribution device

[0027] Fig. 4 - cross-sectional view of the carbon filter distribution device tube

[0028] DETAILED DESCRIPTION OF THE INVENTION

[0029] Definitions and terms:

[0030] Convertible natural gas - natural gas that has been processed to produce synthesis gas;

[0031] Converted gas is the gas obtained after CO2 absorber

[0032] Synthesis gas is a nitrogen-hydrogen mixture obtained after the methanation process.

[0033] According to the scheme shown in Figure 1, the converted natural gas for the production of ammonia passes through processing stages to further obtain synthesis gas. The processing in a particular embodiment includes, sequentially, a hydrogenation unit (1) of sulfur-containing compounds, a desulfurization unit (2) on a zinc absorber, primary (3) and secondary reforming units (4), a catalytic conversion unit (5) of carbon monoxide, an absorption unit (6) for cleaning CO2 from amine solution, then the obtained converted gas is fed to methanation, and the synthesis gas obtained as a result of methanation is fed to the ammonia synthesis column.

[0034] According to the present invention, the unit (6) for absorption purification of converted gas with an ethanolamine solution, which is used to absorb carbon dioxide from a gas stream, comprises a regenerator 61, an absorber 62, a circulation circuit of an amine solution between the absorber and the regenerator, and a filtration unit (60).

[0035] According to the diagram shown in Fig. 2, the unrefined convertible gas with a pressure in the range of 2.5-2.8 MPa and a temperature of 40-65°C is fed into the lower part of the absorber.

[0036] Absorber 62 generally comprises a lower and upper section, each containing at least one layer of packing. The packing may be selected from any randomly distributed packing: Pall rings, Raschig rings, saddle packing, and preferably Pall rings. A process condensate stream is introduced into the upper section of the absorber to reduce amine solution carryover with the gas.

[0037] In the lower section of absorber 62, the converted gas undergoes coarse cleaning with a semi-lean amine solution fed through line IV. In the upper section of the absorber, the converted gas undergoes fine cleaning with a lean, deeply regenerated amine solution (line II). Passing through absorber 62, the amine solution becomes saturated with carbon dioxide, and the saturated, rich amine solution is fed for regeneration through line V.

[0038] An aqueous solution of alkanolamine can be used as an amine solution for purifying the converted gas: monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diglycolamine (DGA), diisopropanolamine (DIPA) and methyldiethanolamine (MDEA), in particular MDEA activated with piperazine (aMDEA), in the preferred embodiment, an aqueous solution of activated methyldiethanolamine with a concentration of 30-50% is used.

[0039] Absorption CO2 removal from converted gas is a mandatory step in ammonia production. The goal is to produce synthesis gas (H2:N2 = 3:1) with a residual CO2 content of no more than 0.03%, as CO2 poisons the NH3 synthesis catalyst. To increase the solubility of carbon dioxide, high pressure is maintained in the absorber, typically in the range of 2.5-2.8 MPa.

[0040] According to the present invention, the regenerator is designed to produce a semi-lean solution - line I, part of which, about 60-70% of the total flow of the semi-lean solution, is sent to rough cleaning of the converted gas in the absorber - line IV, and the other part, line III, is sent to further regeneration to produce a lean deeply regenerated amine solution - line II.

[0041] The deeply regenerated amine solution is fed to the absorber via line II for fine CO2 removal from the converted gas. The temperature of the fed deeply regenerated lean amine solution is 35-50°C.

[0042] The lean amine solution stream leaving the regenerator is pumped by pump 6-1 and enters absorber 62 at a specified flow rate, regulated by valve 60-1. The discharge pressure preferably exceeds the pressure in absorber 62 to create a head reserve, ensuring stable operation of pump 6-1.

[0043] According to the present invention, a filtration unit (60) is installed on line II of the deeply regenerated lean amine solution. A portion, 7-15%, of the "lean" deeply regenerated amine solution supplied to the top of the CO2 absorber is continuously diverted before the shut-off and control valve 60-1 for filtration.

[0044] Over time of use, heat-stable salts, oxidation products, and resinification products accumulate in the amine solution, in particular, bicine, which cannot be restored, impurities (Fe, Cl - , CO…). Their growth reduces the amine's capacity for CO2, increases corrosion, and provokes foaming. To promptly recognize the need for solution purification / replacement, it is preferable to subject the deeply regenerated lean solution to analytical monitoring for undesirable impurities. The advantage of installing a filtration unit containing a carbon filter in the amine purification system for convertible gas for ammonia production on the lean amine solution line provides more precise control of the amine solution, which ensures stable operation of the amine purification system and, consequently, the stable operation of the entire ammonia production system. The sample collection point (SCP) is preferably located after the carbon filter.

[0045] However, installing a filtration unit on the lean amine solution line, i.e., the high-pressure line, entails solving non-trivial engineering problems. Specifically, installing a filter, or even several filters, on the high-pressure line can significantly reduce the flow rate supplied to absorption due to the filter's hydraulic resistance. It is important to maintain approximately the same flow rate after filtration in order to meet the condition Qtotal=Qabsorb+Qfilter, where Qtotal is the flow rate of the total lean amine solution pumped by pump 6-1, Qfilter is the flow rate of the flow diverted for filtration, and Qabsorb is the flow rate of the absorption flow after diverting a portion of the flow for filtration. The filtered lean amine flow is then fed to line II at a specified flow rate to ensure the required lean amine flow rate into the absorber. Maintaining the original lean amine flow rate after filtration is a critical condition for the stable operation of the gas purification system.The absorber is designed for a fixed flow of lean solution in the upper section to uniformly irrigate the contact devices and ensure a specified amine film density on the gas-contact surface. Varying the flow rate disrupts liquid distribution, leading to gas "slippage" past the active zone and a decrease in CO2 purification efficiency (risk of exceeding the permissible value of 0.03%). The lean solution flow rate affects the pressure drop across the absorber, the rate of liquid flow through the packing, and the stability of the distribution devices. A decrease in flow rate leads to underloading of the upper section, which can create localized "dry" zones. An increase in flow rate, however, leads to overloading, flooding, and increased hydraulic resistance.

[0046] Furthermore, control analyses are flow-dependent. A fixed flow rate allows for accurate monitoring of CO2 content in the lean solution.

[0047] Additionally, pump 6-1 is configured to maintain a set flow rate, Qtotal. If the flow rate changes after the filter, the automatic control system will begin to adjust the pump's operation, which will place additional load on the pump, consume excess energy, and create pressure fluctuations in the circuit.

[0048] According to the present invention, the filtration unit 60 comprises at least two filters. Preferably, at least one filter is a carbon filter 601. The filtration unit further comprises a mesh filter (not shown in the figure) for capturing carbon dust, installed downstream of the carbon filter 601. In a preferred embodiment, the filtration unit comprises a cartridge filter 602 located downstream of the carbon filter 601 and the mesh filter. The cartridge filter 602 is generally a filter with a replaceable cartridge. In a particular embodiment, the cartridge can be made of polypropylene.

[0049] Carbon filter 601 is designed to remove large mechanical particles (corrosion products, mechanical particles), high-molecular organic compounds (resins, oligomers), amine degradation products (thermally stable salts, and oxidized compounds). Therefore, placing the TOP after carbon filter 601 allows for analysis of the solution after regeneration and sorption purification, which is important for assessing the solution's readiness for further use in the absorber.

[0050] Installing a cartridge filter downstream of the carbon filter effectively captures residual particles (5-10 µm) and produces a solution with minimal turbidity. A mesh filter (not shown in the figure), installed after the carbon filter and before the cartridge filter, ensures the absence of carbon dust downstream of the carbon filter.

[0051] The carbon filter 601 is configured to be under a pressure of 0.5-2.5 MPa higher than the pressure in the absorber, preferably 0.7-1.7 MPa, and even more preferably 1-1.5 MPa higher than the pressure in the absorber. Preferably, the pressure in the filtration chamber of the carbon filter is higher than or equal to the discharge pressure of the pump 6-1. Advantageously, this allows maintaining a predetermined flow rate of the filtered amine and its flow into the absorber. The predetermined pressure in the filter is provided by the lean amine solution supplied by the pump 6-1 and is regulated by the shut-off and control valve 60-2, configured to remain in the closed position until the predetermined pressure in the carbon filter is reached. The authors hypothesized that at elevated pressure, dissolved gases and organic molecules interact more strongly with the active sites of the carbon.Under pressure, the diffusion of impurities to the carbon surface is accelerated by increasing the solubility of contaminants and reducing the thickness of the boundary layer around the granules. This is why a carbon filter at elevated pressure exhibits a high removal rate of amine degradation products (thermostable salts, oxidized compounds). Furthermore, high pressure reduces the partial pressure of amine and water vapors and suppresses the release of dissolved gases (CO2N2, H2). Consequently, bubble formation in the flow and foaming of the amine solution are reduced. Increased pressure improves flow hydrodynamics by reducing solution viscosity and decreasing the likelihood of localized stagnation zones, ensuring uniform flow distribution across the filter cross-section.

[0052] The filter acts as a pressure tank, maintaining a pressure of 0.5-2.5 MPa higher than the pressure in the absorber, preferably 0.7-1.7 MPa, even more preferably 1-1.5 MPa. It is preferable to maintain the pressure in the carbon filter in the range of approximately 2.9 to 5.3 MPa, preferably 3.2 to 4.5 MPa, even more preferably 3.5 to 3.8 MPa. The pressure in the specified ranges of values ​​allows maintaining a specified flow rate in the filter outlet line. The carbon filter backfill provides significant resistance to the flow, so the flow velocity at the outlet of the carbon filter is significantly reduced. In order to avoid installing additional pumping devices, and to ensure a stable and uniform flow with the ability to adjust its flow rate both up and down, the first filter in the filtration unit downstream, i.e.The carbon filter is normally pressurized, acting as a pressure vessel. The filter vessel smooths out flow pulsations, creating a stable excess pressure of approximately 0.03-0.5 MPa upstream of the absorber, reducing the load on the circulation pump and ensuring a uniform supply of lean amine to the absorber, which is critical for stable mass transfer. Furthermore, with acceptable analytical sample values, it is possible to maintain a stable amine flow rate even if the filter is partially clogged.

[0053] The flow rate is monitored by a flow meter installed downstream of valve 60-2. When the flow rate drops below or exceeds the set value indicated by the flow meter, valve 60-2 regulates the flow rate by increasing or decreasing the opening of the valve 60-2 passage. Thus, by acting as a pressure tank, carbon filter 601 ensures a uniform flow at the set flow rate, capable of overcoming the resistance of subsequent filter devices without the need for additional pumping devices.If the flow rate of the filtered flow is exceeded, if Qfilter + Qabsorb exceeds the permissible value of Qtotal, then after the filtration unit, a discharge of part of the flow before the flow meter into the lean solution receiving section of the regenerator is provided, thus preventing the risk of flooding the absorber, while there is no need to regulate the speed of pump 6-1, which could lead to additional deviations in the flow rate into the absorber.

[0054] At the carbon filter outlet, the flow is able to pass the subsequent cartridge filter without a significant loss of velocity or flow rate. Therefore, the flow in the feed line from the regenerator to the absorber does not lose velocity even while passing through the filtration unit, and there is no need to install additional pumping devices to reach the absorber.

[0055] Even with the gradual reduction in flow velocity as it passes through the pipelines and control valves, the filtered amine solution stream combines with the amine solution in the pipeline, imparting additional velocity to the amine stream entering the absorber. Thus, the amine stream enters the absorber with a slight excess pressure; i.e., the pressure of the amine stream entering the absorber exceeds the pressure in the absorber. This compensates for hydraulic losses in the absorber's distribution devices, ensuring uniform liquid distribution across the absorber cross-section and uniform irrigation of the absorber packing, leading to an increased gas-amine contact area and, consequently, more efficient CO2 absorption.

[0056] The carbon filter shown in Fig. 3 with the clarifying views in Figs. 4 and 5 generally has an elongated stainless steel body, preferably at least 3 cm thick, in particular 4 cm thick. The top and bottom are arched, also made of stainless steel of the same thickness.

[0057] The interior of the housing contains a filtration chamber that can be filled with a filter medium, which can be activated wood, hard coal, anthracite, or mixtures thereof. In this particular case, activated birch carbon with a particle size of 1-4 mm is used.

[0058] Activated charcoal, due to its low bulk density, allows for easier flow and a smaller pressure drop, as well as lower flow resistance. Charcoal is preferred due to its absorption properties and low bulk density, but it is more brittle than, for example, hard coal. Therefore, it is preferable to reduce the impact load from the solution flow under pressure by ensuring a uniform flow rate within the charcoal mass and avoiding compacted areas of increased density, which reduce filtration efficiency. If the top layer of the backfill becomes compacted, the solution passages become clogged, leading to complete backfill replacement, even if the underlying charcoal is still functional.

[0059] Therefore, for effective filtration, it is preferable that the solution supply be as uniform as possible, preferably multi-jet.

[0060] The interior space beneath the upper dome of the housing contains a distribution device capable of multi-jet delivery of the lean amine solution for filtration. Multi-jet delivery is accomplished through openings arranged in one or more rows, preferably in an upward direction.

[0061] Injecting the amine solution into the carbon filter using a multi-jet method is preferable due to the high pressure created within the filter. Single-jet injection at high pressure and, consequently, flow rate, can lead to localized overloads in the filter, creating zones of excess flow where the activated carbon quickly wears out, and zones of insufficient contact where cleaning efficiency is reduced. Smooth flow distribution minimizes turbulence, primarily preventing foaming. At the same time, the carbon is uniformly saturated with contaminants throughout the entire carbon bed, allowing for backwashing / regeneration with equal effectiveness in all zones, preventing the formation of "dead" areas where the carbon is not restored.

[0062] In particular, the distributor is a collector-beam device comprising beams, uniformly spaced radially from each other, emanating from a central collector. The beams are made of stainless steel tubes with plugs at the ends and with openings evenly distributed along the length of the tube. The distributor preferably has 2 to 10 beams, uniformly spaced radially from each other, preferably 6-8 beams. Considering the delivery of the amine solution under the discharge pressure of pump 6-1, which is in particular 2.9-3.8 MPa, it is preferable to direct the distribution openings of the distributor upward.

[0063] The holes in the tube are preferably arranged in one or more rows. The number of holes is selected based on uniform coverage of the coal bed and depends on the filter diameter. Furthermore, the hole spacing affects the height of the exiting jet. To prevent the jets from reaching the upper arch and reduce their velocity at the distributor outlet, it is preferable to arrange the holes as closely as possible based on the strength calculation of the distributor beam design. In a particular embodiment, the beam contains holes every 10-6 mm. Reducing the speed of the solution jets supplied under pressure reduces the impact load on the coal bed, ensuring a uniform flow rate throughout the coal mass and avoiding compacted areas of increased density, which reduce filtration efficiency.

[0064] The distribution device can be duplicated along the height of the central collector with or without offset in the radial direction relative to the first one.

[0065] In the two-row arrangement, adjacent holes in adjacent rows are directed upward and sideways at an angle to the vertical axis. In a specific arrangement, the angle is 20-30° to the vertical. The upward and sideways orientation of the holes further reduces the impact load on the coal backfill. The holes in a row can be staggered relative to the holes in the adjacent row, or opposite each other. A staggered arrangement is preferable due to better flow distribution.

[0066] A perforated plate is installed in the interior space near the lower arch of the filter housing. To reduce the risk of carbon particle carryover from the filter, the inner perforated plate is preferably lined with at least one layer of mesh. Furthermore, the mesh, acting as an additional factor of hydraulic resistance, equalizes the flow velocity across the entire filter cross-section, preventing the formation of high-velocity channels. This increases filtration efficiency, i.e., the degree of solution purification, ensuring longer contact of the solution with the carbon. In a specific embodiment, two layers of mesh are installed. In a specific embodiment, each layer has a different mesh size. Preferably, the mesh size of the first layer, located adjacent to the carbon backfill, is larger than the mesh size of the second layer, located between the first layer and the perforated plate.Example of mesh installation: Layer 1 – mesh with a 6-mesh opening and 1 mm wire thickness; Layer 2 – mesh with a 2.5-mesh opening and 0.4 mm wire thickness. The mesh material is selected from corrosion-resistant materials such as polymer or stainless steel, such as 12X18H10T.

[0067] To maintain a low viscosity of the lean amine solution, especially in cold weather, the filter housing is preferably equipped with a heating element located along the outer wall of the housing. This heating element is designed to maintain the operating temperature of the ethanolamine solution at 45-60°C. Reducing the solution viscosity primarily improves flow through the carbon bed, reducing the pressure drop across the filter and eliminating stagnant zones where impurities accumulate. Furthermore, maintaining a uniform, optimal solution temperature throughout the filter increases the diffusion coefficient of dissolved substances. Impurity molecules reach the active sites of the carbon more quickly, promoting effective filtration. The heating element can be an electric heater or, preferably, a coil with a circulating coolant inside. The coolant is either steam or water.

[0068] The carbon filter is designed to operate both sequentially and separately with a cartridge filter to ensure the ability to replace filter elements - filling with carbon or cartridges, without stopping the filtration process.

[0069] An amine solution is pumped into the carbon filter's filtration chamber to a predetermined pressure, which is greater than or equal to the pump's discharge pressure. The shut-off valve remains closed until the predetermined pressure in the carbon filter is reached. The flow rate from the filter outlet is then regulated by the same shut-off valve within the required range to ensure the required flow rate to the absorber.

[0070] Example

[0071] At the production site of JSC Ammonium, amine purification of convertible gas in ammonia production is carried out according to the present invention.

[0072] The amine solution is a commercially available aMDEA. The filtration unit consists of a carbon filter, a mesh filter, and a cartridge filter installed in series. The carbon filter contained Carboclean 12×40 activated birch carbon from Uralkhimsorb LLC.

[0073] The pressure in the carbon filter was between 3.5 and 3.8 MPa.

[0074] The flow rate of the "lean" deeply regenerated a-MDEA solution into the upper part of the CO2 absorber on the distribution plate is in the standard range of 510 to 590 nm 3 / h

[0075] The amount of solution diverted for filtration is no more than 45 nm 3 / h.

[0076] During the year since the last change of coal filling, the amine solution after the carbon filter was regularly analyzed for foaming.

[0077] The determination of foaming is based on bubbling air into alkanolamine solutions and measuring the volume from 0.0 to 400 cm 3and stability (sec) of the resulting foam.

[0078] 150 cm of gas was placed in a graduated cylinder with an air supply device. 3 solution of lean aMDEA. Air was passed through with a volumetric flow rate of (1000±25) cm 3 / min. When air bubbles appeared in the test solution, the stopwatch was started. After 5 minutes, the air supply was stopped, the volume of foamed liquid was measured at the top of the resulting foam, and foam stability was determined, i.e., the time it took for the foam to dissipate (until the bubbles on the surface of the liquid disappeared). The volume of foam formed was calculated as the difference between the volume of foamed liquid and the volume of liquid before the air was introduced.

[0079]

[0080] As can be seen from the analysis results, after approximately one year of continuous operation, foaming has increased slightly and is significantly below the upper limits of the norm.

Claims

1. A filtration unit located on the line of a deeply regenerated amine solution coming from a regenerator to an absorber, wherein the unit contains at least one injection pump and at least two filters, wherein the first filter, located upstream from the second filter, is a carbon filter, wherein the amine solution is fed into the carbon filter at the injection pressure of the injection pump, wherein the pump injection pressure value is lower than or equal to the pressure value in the filtration chamber of the carbon filter, wherein the amine solution is fed into the carbon filter in a multi-jet manner.

2. The unit according to claim 1, configured to maintain the pressure in the filtration chamber of the carbon filter at 0.5-2.5 MPa, preferably at 0.7-1.7 MPa, even more preferably at 1-1.5 MPa higher than the pressure in the absorber located downstream from the filtration unit.

3. The unit according to claim 1, configured to maintain pressure in the filter filtration chamber from 2.9 to 5.3 MPa, preferably from 3.2 to 4.5 MPa, even more preferably from 3.5 to 3.8 MPa.

4. An assembly according to any of the preceding claims, wherein the discharge pressure of the injection pump is from 2.9 to 3.8 MPa.

5. The unit according to claim 1, in which the jets of amine solution are directed upward.

6. The unit according to item 2, in which the jets are directed upward and sideways.

7. The unit according to claim 1, wherein the carbon filter contains a filter medium that is one or more of the following: activated charcoal, hard coal, anthracite.

8. The unit according to claim 1, in which the carbon filter performs the function of a pressure tank.

9. The unit according to claim 1, in which the filtration unit comprises a shut-off and control valve installed at the outlet of the carbon filter and configured to remain in the closed position until a predetermined pressure is reached in the carbon filter.

10. The unit according to claim 9, in which the shut-off and control valve is designed to regulate the flow rate of the amine solution from the carbon filter.

11. The unit according to claim 1, wherein the first and second filters are designed to operate separately.

12. The unit according to claim 1, wherein the amine solution is a deeply regenerated aqueous solution of activated methyldiethanolamine with a concentration of 30-50%.

13. The assembly of claim 1, wherein the second filter is a cartridge filter located downstream of the carbon filter.

14. The unit according to claim 13, wherein the cartridge filter comprises a replaceable cartridge made of polypropylene.

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