GAS DRYING PROCESS

Abstract

GAS DRYING The present invention relates to a method for drying a wet matrix by temperature-controlled adsorption (TCA), characterized in that it comprises at least one step of contacting the matrix with an adsorbent comprising at least one zeolite with a micropore size strictly greater than 0.4 nm and less than 0.75 nm, a Si / Al atomic ratio between 1.4 and 20, and an accessible volume, measured by water adsorption, strictly greater than 5% and strictly less than 35%. The invention also relates to the use of said method for drying a wet liquid or gaseous organic matrix. Fig. 1

Description

Title of the invention: GAS DRYING METHOD

[0001] The present invention relates to the field of gas drying and more specifically to the drying of gases using zeolitic adsorbents and more particularly to the field of gas drying using zeolitic adsorbents according to the so-called Temperature Modulated Adsorption technology.

[0002] Temperature Swing Adsorption, or ATM, or "Temperature Swing Adsorption" or simply "TSA" in English, is a process for separating gas mixtures in which the adsorption of a gas by a solid or liquid at a given temperature takes place alternately, followed by its desorption at a higher temperature.

[0003] Temperature-modulated adsorption utilizes the temperature dependence of adsorption. The adsorbent charged with the compound to be separated is largely freed of this compound in a subsequent step by means of the introduction of thermal energy. For continuous operation of a temperature-modulated adsorption system, at least two adsorbents are required, one being charged and the other being desorbed. For heating, a hot gas, typically a fraction of the dried gas or hot nitrogen, is generally used.

[0004] Unlike pressure swing adsorption (PSA), temperature-modulated adsorption requires thermal energy, which is less expensive than mechanical energy. It can also be used in material systems with high adsorption enthalpies. Cycle times are generally several hours.

[0005] Thus, temperature-modulated adsorption is preferably used to remove compounds at low concentrations with high enthalpies of adsorption. This technique is used, for example, for gas drying, the removal of sulfur compounds from natural gas, or solvent recovery.

[0006] Variable or modulated temperature adsorption plants and TSA concepts have been patented and used for gas purification (especially natural gas) since the 1950s. Since their first use, TSA systems have seen rapid progress in research and development.

[0007] Patent CA704265 A demonstrates that zeolite 4A is the most suitable for gas drying. Adsorption isotherms clearly show its high adsorption capacities at very low water contents, as well as comparisons with other types of adsorbents, particularly silica gel and activated alumina.

[0008] US patent 8784533 describes a multi-stage modulated adsorption process, particularly for the removal of CO2 and / or H2S present in natural gas. This process involves adsorbent solids that are regenerated with steam. Therefore, this process is not suitable for gas drying applications.

[0009] Generally speaking, commonly used TSA processes employ fixed beds or rotating systems. The industry today uses a wide variety of concepts, ranging from conventional two- or three-bed fixed systems to indirect solutions or those coupled with other regeneration processes, including pressure swing adsorption (PSA), vacuum swing adsorption (VSA), and others. The TSA process is most frequently used for natural gas dehydration.

[0010] Furthermore, and as previously indicated, TSA processes employ at least two adsorbents, most often identical, each playing the respective role of adsorbent material and material to be desorbed. The desorption of the material, also called adsorbent regeneration, is generally and most often carried out by heating said adsorbent.

[0011] More specifically, a temperature-controlled adsorption (TCA) process comprises a first step in which a liquid or gaseous matrix (M), containing a high water content, is brought into contact with an adsorbent (A), most often by passing it through a bed of adsorbent. The matrix (M) is then separated from the adsorbent (A) with a reduced water content, the water having been retained by the adsorbent (A).

[0012] The amount of water adsorbed defines the water adsorption capacity of the adsorbent (A). When this capacity is reached, it is then necessary to regenerate the adsorbent (regeneration step), that is, to desorb the adsorbed water in order to restore all or part of its adsorption capacity. This regeneration is achieved by supplying energy, typically by increasing the temperature to a temperature known as the desorption temperature.

[0013] A commonly used technique consists of taking a fraction of the dried matrix and then heating this fraction, typically with a heat exchanger, to temperatures of approximately 230°C to 300°C, depending on the type of matrix and adsorbents used. The dry, heated matrix fraction is brought into contact, typically by countercurrent flow through a water-charged adsorbent bed. This step both desorbs the water adsorbed onto the adsorbent and saturates the heated matrix fraction with water. The heated, water-charged matrix fraction is then cooled to the temperature of the drying process described above, and the water present in said matrix fraction is condensed and separated. Finally, said fraction matrix at process temperature is reinjected into the initial matrix via a compressor.

[0014] While this TSA drying process is now widely and commonly used, it nevertheless presents numerous critical points, among which we can mention: • The final water content (residual water) of the matrix at the adsorbent outlet must be reduced as much as possible because under the necessary temperature and pressure conditions to which the matrix is ​​subjected (for example during its transport), some organic molecules can react with water molecules to form solid compounds, called hydrates, which, once formed, can cause clogging in pipes, valves and other parts, which often leads to significant problems; in order to avoid the formation of such hydrates, water contents at the outlet of the adsorption column are most often recommended to be less than 1 ppmv, preferably less than 0.1 ppmv; • the water adsorption capacity of the adsorbent, which should be as high as possible to reduce the number of regeneration steps; and • the regeneration stage which corresponds to the desorption of water adsorbed by the adsorbent and which is most commonly carried out by direct or indirect heating of said adsorbent; this heating is generally carried out by combustion of natural gas, which represents the most energy-intensive and therefore the most expensive stage of the temperature modulated adsorption drying process; a lowering of the regeneration temperature would thus bring about a significant reduction in production costs, provided that the specifications (especially for residual water) are met.

[0015] By way of example, the processes generally implemented today for drying an organic matrix successfully use adsorbents comprising mainly LTA-3A, LTA-4A, or CHA zeolites. However, a regeneration step between each adsorption cycle is essential for the proper functioning of the process. This regeneration step (desorption of the adsorbed water) is generally carried out at temperatures at least equal to the recommended desorption temperatures depending on the nature of the zeolite, and in particular at least 280°C for an LTA-4A zeolite, at least 230°C for an LTA-3A zeolite, and at least 250°C for a CHA zeolite.

[0016] These desorption temperatures involve very significant amounts of heat. Reducing these amounts of heat supplied to the system could significantly decrease the overall cost of the process and thus the overall production cost.

[0017] Furthermore, lowering the amount of heat supplied to the system would help to address the problem of global warming and the increase in the cost of energy, especially natural gas, and thus contribute to the optimization of industrial processes to make them less energy-intensive.

[0018] As demonstrated above, in the case of TSA drying processes, the most significant energy expenditure occurs during the regeneration stage, and a reduction in the amount of heat supplied to the system would significantly increase the process's profitability. However, there is a risk that a decrease in the amount of heat during the regeneration stage could lead to a less well-regenerated adsorbent, and therefore a lower water adsorption capacity and, at the process outlet, a larger residual water content in the matrix.

[0019] Thus, one objective of the present invention is to provide a temperature-controlled adsorption drying process for liquid or gaseous matrices, in which the amount of energy supplied to the overall system is substantially reduced, and in particular the amount of energy supplied to regenerate the adsorbent is substantially reduced, while maintaining a water content in the matrix at the end of the drying process—that is, a residual water content in the matrix at the end of the drying process—that conforms to the required specifications. Other objectives will become apparent in the following description of the invention.

[0020] The Applicant has now shown that it is possible to conduct a temperature-modulated adsorption drying process by lowering the regeneration temperature while maintaining a very low residual water content, and in some cases by keeping the residual water below the required specification of 0.1 ppm by volume (ppmv) of water.

[0021] Thus, and according to a first aspect, the present invention relates to a method for drying a matrix by temperature-controlled adsorption (TCA), characterized in that it comprises at least the following steps: a) supply of a wet matrix, liquid or gaseous, b) contacting said wet matrix with an adsorbent Ao capable of adsorbing water from said wet matrix, the contact being carried out at a pressure Po between 15 bar (1.5 MPa) and 130 bar (13 MPa), preferably between 20 bar (2 MPa) and 80 bar (8 MPa), and a temperature To between 5°C and 80°C, preferably between 5°C and 70°C, preferably again between 5°C and 60°C, c) recovery of a dry matrix fraction comprising a water content of less than 1 ppmv,

[0022] d) contacting the remaining fraction of dry matrix with an adsorbent Ai that has adsorbed water in a previous adsorption step, at a pressure Pi including between 15 bar (1.5 MPa) and 130 bar (13 MPa), preferably between 20 bar (2 MPa) and 80 bar (8 MPa), and heated to a desorption temperature TH generally between 100°C and 280°C, preferably between 110°C and 250°C, advantageously between 110°C and 230°C, or even better, for example, between 110°C and 210°C, in order to desorb at least part of the water contained in said adsorbent Ab

[0023] e) recovery of the remaining fraction of the now moist matrix, then returning to pressure PO and temperature T0,

[0024] f) injection of said remaining fraction of wet matrix in step a), process wherein the adsorbent Ao and the adsorbent Ai each comprise at least one zeolite, said zeolite having at least the following characteristics: 1. Micropore size, determined by liquid nitrogen intrusion, strictly greater than 0.4 nm and less than 0.75 nm, 2. an atomic ratio of Si / Al between 1.4 and 20, inclusive, 3. an accessible volume, measured by water adsorption, strictly greater than 5%, preferably strictly greater than 7%, preferably still strictly greater than 9% and advantageously strictly less than 35%, advantageously strictly less than 32%.

[0025] It should be understood that the process of the invention is preferably and very advantageously operated in continuous mode. It is possible to operate in discontinuous mode, or batch mode, although this option is not preferred for industrial drying processes.

[0026] The wet matrix that can be implemented in the process of the invention can be any liquid or gaseous matrix comprising an amount of water between 0.1 ppm by volume (ppmv) of water and the water saturation of said matrix, and for example comprising an amount of water between 0.1 ppmv of water and 2000 ppmv of water, preferably between 0.1 ppmv of water and 1000 ppmv of water.

[0027] The wet matrix to be dried used in the process of the invention can therefore be of any type and in particular a gas or a liquid. Among the gases, we may mention, without limitation, natural gas, air, hydrogen, carbon dioxide (CO2), cracked gases, gaseous hydrocarbon cuts, and among the liquids, we may mention, without limitation, organic liquids, alcohols, organic peroxides, liquefied gases, for example liquefied petroleum gas (LPG), and others.

[0028] The adsorbent suitable for drying the matrix according to the process of the invention can be any any type of mineral or organic material, provided it includes at least one zeolite exhibiting the characteristics defined above. Thus, the adsorbent suitable for drying the matrix according to the process of the invention can be any type of mineral or organic material, natural, synthetic, or artificial, exhibiting microporosity that allows it to adsorb water molecules, and may further include, for example, and in a non-standard manner limiting, one or more other adsorbent components chosen from zeolites, aluminas, silica gels, MOFs, as well as mixtures of two or more of them.

[0029] Preferably, the adsorbent usable in the context of the process of the present invention comprises, and preferably consists of, a zeolite or a mixture of zeolites having the characteristics described above, or a zeolite agglomerate comprising at least one zeolite having the characteristics described above, and at least one agglomeration binder.

[0030] The preferred zeolites for the process of the present invention are FAU Y type zeolites, with Si / Al molar ratios between 1.4 and 20, preferably between 2.5 and 12, and MFI zeolites with Si / Al molar ratios between 10 and 20, preferably between 10 and 18, and even more preferably between 12 and 16. These zeolites are most often and very advantageously used in the form of agglomerates, well known to those skilled in the art, these agglomerates being able to include agglomeration binders, the agglomeration binder being optionally zeoliticized, these binders being able to be clays, in particular clays selected from attapulgite, bentonite, halloysite, kaolin, and mixtures of two or more of them.

[0031] The pressure Po of step b), generally and advantageously between 15 bar (1.5 MPa) and 100 bar (10 MPa), is a necessary and sufficient pressure to allow the flow of the wet matrix through the adsorbent intended to dry said wet matrix. Similarly, the temperature To of step b) is a temperature such that it allows the efficient adsorption of the water contained in the wet matrix by the zeolite adsorbent.

[0032] At the end of step b), the matrix stream is a dry matrix stream, i.e., having lost all or part of its water content by adsorption onto the zeolite adsorbent. According to the invention, and in a preferred embodiment, the dry matrix fraction recovered in step c) comprises a water content of less than 1 ppmv, preferably less than 0.5 ppmv, and even more preferably less than 0.1 ppmv.

[0033] This water content of less than 1 ppmv, preferably less than 0.5 ppmv, and particularly less than 0.1 ppmv, is the minimum water content currently recognized as the maximum content to avoid any potential problems with hydrate formation in liquid or gaseous matrices, regardless of the temperature and pressure within said matrix. It is indeed very important to avoid, as much as possible, any formation of hydrates, which are often responsible for blockages, clogging, and fouling of pipes, valves, pumps, and other means of transporting and conveying said liquid or gaseous matrices.

[0034] In a preferred embodiment of the process of the invention, the fraction x of dry matrix recovered in step c) is generally between 70% and 99% by volume, preferably between 80% and 95% by volume. The remaining fraction y which is engaged in step d) is the complement to 100%, i.e. y = 100 - x.

[0035] The fraction y is a dry matrix fraction which is engaged in step d) on an adsorbent Ai already saturated with water. This adsorbent Ai may be identical or different from the adsorbent Ao; preferably the adsorbent Ai is identical to the adsorbent Ao, for obvious reasons of ease of implementation of the overall industrial installation.

[0036] This step d) of the process of the invention therefore aims to regenerate the adsorbent Ai, that is to say, to desorb the water from the adsorbent Ai by bringing it into contact with the fraction y of the dry matrix obtained from process c). The fraction y of the dry matrix will therefore become saturated with water upon contact with the adsorbent Ai, in order to desorb at least part of the water contained in said adsorbent Ab

[0037] As previously stated, the process of the present invention is characterized in particular by the fact that the process uses an adsorbent comprising a very specific zeolite, said at least a zeolite having at least the following three characteristics: 1. Micropore size, determined by liquid nitrogen intrusion, strictly greater than 0.4 nm and less than 0.75 nm, 2. an atomic ratio of Si / Al between 1.4 and 20, inclusive, 3. an accessible volume, measured by water adsorption, strictly greater than 5%, preferably strictly greater than 7%, preferably still strictly greater than 9% and advantageously strictly less than 35%, advantageously strictly less than 32%.

[0038] The zeolite defined above and present in the adsorbent used in the process of the invention offers the dual advantage of eliminating, or at least reducing, the water content in a liquid or gaseous matrix and requiring a very reasonable amount of heat for its regeneration, particularly less than the amount of heat usually and commonly observed in TSA drying processes. In other words, despite the significant energy savings, the structure of the zeolite in the adsorbent allows for very satisfactory adsorption of water molecules, so that the specifications at the adsorber outlet, in particular a water content less than or equal to 1 ppmv, are met.

[0039] According to a preferred embodiment, step d) of the process of the invention is carried out at a pressure Pi generally between 1 bar (0.1 MPa) and 130 bar (13 MPa), preferably between 5 bar (0.5 MPa) and 80 bar (8 MPa), and most often at a pressure Pi on the order of the pressure Po. Step d) of the process of the invention consists of desorbing The adsorbent therefore requires an energy input (calories) by heating, specifically to a desorption temperature Ti generally between 100°C and 280°C, preferably between 110°C and 250°C, depending on the nature of the adsorbent, the quantity of water to be desorbed, and the flow rates used, in order to desorb at least part of the water contained in said adsorbent Ab

[0040] This temperature can also in some cases be between 110°C and 250°C, for example between 110°C and 210°C. In a preferred embodiment, the amount of heat is reduced compared to that applied in current drying processes, which represents a substantial reduction in energy costs. Thus, the regeneration temperature applied in the process of the present invention can preferably be between 110°C and 190°C or even in a range from 140°C to 250°C, depending on the nature of the adsorbent, the quantity of water to be desorbed and the flow rates used, in order to desorb at least part of the water contained in said adsorbent Ab. Thus, the reduction in the quantity of heat can be reduced by at least 5%, or even by at least 10%, advantageously by at least 20%, better still by at least 30% compared to a process carried out with a regeneration temperature of 300°C (total or almost total desorption).

[0041] Without being bound by theory, it should be understood that the characteristics of at least one zeolite present in the adsorbent used in the process of the present invention result in weaker binding of water molecules in the micropores of the zeolite and consequently lead to a lower amount of energy required to desorb the adsorbed water molecules, and thus a lower regeneration temperature than that commonly applied and recommended by adsorbent manufacturers. The zeolite present in the adsorbent used in the process of the present invention could thus be described as a "low hydrophilic" or even "hydrophobic" zeolite, thus highlighting its less hydrophilic nature compared to the zeolites commonly used in TSA drying process adsorbers known today.

[0042] It has been observed, quite surprisingly, that the "low hydrophilicity," or even "hydrophobicity," of the zeolite included in the adsorbent used in the process of the present invention does not significantly alter the drying quality, and that the matrix at the end of step c) always has a water content that meets the requirements, particularly preventing the formation of hydrates, and in particular a water content of less than 0.1 ppmv. Another advantage is that the productivity of the overall process of the present invention is not substantially affected.

[0043] Indeed, another advantage linked to the at least partial regeneration of the adsorbent implemented in the present invention is the increase in the The lifespan of the adsorbent is extended. Because the adsorbent is subjected to lower temperatures, particularly lower than the regeneration temperatures recommended by manufacturers, it degrades less rapidly. Consequently, adsorbents are replaced less frequently, resulting in less frequent industrial downtime and thus improved productivity.

[0044] And as indicated above, it has been observed quite unexpectedly that the drying process of the present invention, despite a lower regeneration temperature than that known in the prior art, and therefore a reduced adsorption capacity of the adsorbent, makes it possible to achieve quite suitable and acceptable degrees of drying and in particular to obtain a matrix comprising a water content conforming to the specifications usually required, and more particularly a water content of less than 1 ppmv.

[0045] After at least partial regeneration of the adsorbent Ai by contacting it with the fraction y, this matrix fraction is then saturated with water. This water-saturated fraction is then cooled, advantageously to pressure Po and temperature To. This step removes a large portion of the water contained in the matrix fraction, which is then reintroduced in step a) of the process to be dried.

[0046] The process of the present invention thus represents a very interesting technological advance from an economic point of view since the overall amount of energy required for the operation of the process can be substantially reduced and in particular the amount of heat supplied to the overall process can be substantially reduced compared to the TSA drying processes known in the prior art.

[0047] In the description of the present invention, the term "contacting" generally and preferably means contact of a continuous matrix flow, said contact being of variable duration, generally from a few tenths of a second to a few minutes. This contacting of the matrix with an adsorbent can advantageously and most often be achieved by continuously passing said matrix through a bed of adsorbent, according to conventional techniques well known to those skilled in the art. Most often and preferably, the adsorbent beds are placed in columns called adsorption columns.

[0048] In a preferred embodiment, the process comprises a first adsorption column containing the adsorbent Ao capable of adsorbing the water contained in the matrix to be dried and a second column containing the adsorbent Ai which is to be totally or at least partially desorbed by means of the fraction of matrix dried on the adsorbent Ao. This process operates continuously. When the water breaks through the first column, i.e., when the residual water content at the outlet of the adsorbent If the water content of adsorbent Ao exceeds the normally required specifications (typically 0.1 ppmv of water), then said adsorbent Ao must be regenerated. According to the process of the invention, it is then not necessary to stop the installation to replace the saturated adsorbent, but simply to bring the wet matrix to be dried into contact with the adsorbent Ai, which has been at least partially desorbed by the fraction y of dry matrix, as described above.

[0049] And during contact with the adsorbent Ai, the adsorbent Ao is regenerated by a new fraction of dry matrix resulting from adsorption on the adsorbent Ab. Thus, the process according to the invention can be operated continuously using at least two columns of adsorbents, while one of the columns is used to dry the matrix, the other column is regenerated, totally or at least partially, with a fraction of dry matrix, as indicated above.

[0050] The process of the present invention can of course be applied once or several times, in association or not with other drying or even purification processes, in particular with PSA and / or TSA processes.

[0051] Thus, and thanks to its particular properties and advantages, the drying process of the present invention can be implemented in a large number of fields of application and in particular the drying of gases and liquids and in particular the drying of natural gas, air, hydrogen, carbon dioxide (CO2), cracked gases, gaseous hydrocarbon cuts, organic liquids, alcohols, organic peroxides, liquefied gases, for example liquefied petroleum gas (LPG), and others.

[0052] According to another aspect, the present invention relates to the use of the drying process as just described for the drying of a liquid or gaseous matrix, in particular of a liquid or gaseous matrix comprising a water content of between 0.1 ppm by volume and the water saturation of said matrix, preferably comprising a water content of between 0.1 ppm by volume and 2000 ppm by volume, preferably further comprising a water content of between 0.1 ppm by volume and 1000 ppm by volume.

[0053] The use according to the present invention is particularly suitable for drying natural gas, air, hydrogen, carbon dioxide, cracked gases, gaseous hydrocarbon cuts, organic liquids, alcohols, organic peroxides, liquefied gases, for example liquefied petroleum gas, and others.

[0054] The invention is now illustrated by means of the following examples, which in no way limit the invention, the scope of which is defined by the claims annexed to this description. Brief description of the figures

[0055] Figure 1 illustrates the drying process according to the invention, in which a wet matrix (1) is introduced into a first column (A) containing the adsorbent A0, allowing the matrix to be dried to obtain a dry matrix (2). A fraction of this dry matrix is ​​heated in the heat exchanger (C) for contact in the column (B) containing the adsorbent Ai, which is to be regenerated totally or at least partially. The wet matrix fraction flowing from column (B) is then cooled in the heat exchanger (D), thus allowing the separation of the desorbed water in the separator (E). This matrix fraction is then reinjected by means of the injector (F) along with the wet matrix flow to be dried (1). Analytical methods Si / Al atomic ratio:

[0056] The Si / Al atomic ratio can easily be determined from an elemental chemical analysis of the adsorbent. Such an elemental chemical analysis can be carried out using various analytical techniques well known to those skilled in the art. Among these techniques is the X-ray fluorescence chemical analysis technique as described in standard NF EN ISO 12677:2011, which can be performed using a wavelength dispersive X-ray fluorescence (WDXRF) spectrometer, for example, the Tiger S 8 from Bruker.

[0057] X-ray fluorescence is a non-destructive spectral technique that exploits the photoluminescence of atoms in the X-ray range to determine the elemental composition of a sample. Excitation of atoms, generally by an X-ray beam or by bombardment with electrons, generates specific radiations after the atom returns to its ground state. The X-ray fluorescence spectrum has the advantage of being largely independent of the chemical composition of the element, thus providing a precise determination, both quantitative and qualitative. After calibration, a measurement uncertainty of less than 0.4% by weight is typically obtained for each oxide.

[0058] These elemental chemical analyses make it possible to verify the Si / Al atomic ratio of the adsorbent used. In the description of the present invention, the measurement uncertainty of the Si / Al molar ratio measured afterward is ± 0.2 in relative %. Pore ​​size:

[0059] Pore size is measured according to the Barrett-Joyner-Halenda method (BJH method, proposed in 1951) by measuring the adsorption isotherm of a gas, such as nitrogen, at its liquefaction temperature. Interpreting the nitrogen adsorption isotherm at 77 K using the Barrett-Joyner-Halenda method (BJH method, proposed in 1951) also allows for obtaining the pore size distribution, and in particular the micropore distribution.

[0060] Prior to adsorption, the zeolite adsorbent is degassed between 300°C and 450°C for a period of between 9 and 16 hours under vacuum (P < 6.7 x 10⁴ Pa). The nitrogen adsorption isotherm at 77 K is then measured on a Micromeritics ASAP 2020 M instrument, taking at least 35 measurement points at relative pressures with a P / Po ratio between 0.002 and 1. Measurement of accessible volume:

[0061] The accessible volume is measured by water adsorption at a relative pressure of 0.5. This method consists of measuring the weight increase of a sample placed in a sealed chamber at a constant humidity of 50% and a temperature of 23°C for 24 hours. This weight increase represents a water adsorption capacity expressed as a percentage, which is interpreted as the accessible porous volume, more simply called the "accessible volume".

[0062] In calculating the pore volume, the density of the liquid phase is assumed to be identical to the density of the adsorbed water, i.e., 1). The accessible volume is therefore equivalent to the water adsorption capacity expressed as a percentage. The sample is first heated in an oven at 550°C under an airflow for 1 hour to release the porosity. Examples

[0063] The gains in the quantity of heat supplied to the process for drying a wet matrix (natural gas containing approximately 2000 ppmv of water) were studied with different tests, in which all the parameters are fixed and identical for all the tests, with the exception of the regeneration temperature.

[0064] The quantity of heat QT (in kJ) required to regenerate the adsorbent is calculated according to the following formula:

[0065] [Math 1]

[0066] QT(enkJ) = Ql + Q2

[0067] in which Q1 represents the amount of heat required to heat the adsorbent, and Q2 represents the amount of heat required to desorb the water.

[0068] The quantity of heat Q1 is calculated according to the following formula:

[0069] [Math 2]

[0070] Q1 (in kJ) = nqCpAT, in which mi represents the mass of the adsorbent (in kg), Cp represents the heat capacity of the adsorbent (in kJ / (kg.°C)), and AT represents the temperature variation between the regeneration temperature Ti and the adsorption temperature To (in °C).

[0071] The quantity of heat Q2 is calculated according to the following formula:

[0072] [Math 3]

[0073] Q2 (in kJ) = m2AHdes in which m2 represents the amount of water adsorbed, AHdes represents the heat of desorption of water on the adsorbent.

[0074] The water capacity (Ce) of the adsorbent is calculated according to the following equation:

[0075] [Math 4] _ _(adsorption rate x water content of the wet matrix x breakthrough time) ~ mass of the adsorbent and the breakthrough time is equal to the duration of the column adsorption time, that is to say the time elapsed between the entry of the wet matrix and the breakthrough (i.e. water content > 1 ppmv at the column outlet) under the operating conditions of the example.

[0076] These examples show that it is possible to optimize the regeneration conditions, in particular by reducing the regeneration temperature, while obtaining a dry matrix, the water content of which is on the one hand acceptable and conforms to the specifications (< 1 ppmv) and on the other hand quite comparable to that obtained with a conventional drying process which is much more energy-intensive because the regeneration temperature is much higher than that applied in the process of the invention.

Claims

1. Demands A process for drying a matrix by temperature-controlled adsorption (TCA), characterized in that it comprises at least the following steps: a) supply of a wet matrix, liquid or gaseous, b) bringing said wet matrix into contact with an adsorbent Ao capable of adsorbing water from said wet matrix, the contact being carried out at a pressure Po between 15 bar (1.5 MPa) and 130 bar (13 MPa), preferably between 20 bar (2 MPa) and 80 bar (8 MPa), and a temperature To between 5°C and 80°C, preferably between 5°C and 70°C, preferably again between 5°C and 60°C, c) recovery of a dry matrix fraction comprising a water content of less than 1 ppmv, d) Contacting the remaining dry matrix fraction with an adsorbent Ai that has adsorbed water in a previous adsorption step, at a pressure Pi between 15 bar (1.5 MPa) and 130 bar (13 MPa), preferably between 20 bar (2 MPa) and 80 bar (8 MPa), and heated to a desorption temperature Tb generally between 100°C and 280°C, preferably between 110°C and 250°C, advantageously between 110°C and 230°C, or even better, for example, between 110°C and 210°C, in order to desorb at least part of the water contained in said adsorbent Ab e) recovery of the remaining fraction of the now moist matrix, then re-establishment at pressure PO and temperature T0, f) injection of the said remaining fraction of wet matrix in step a), process wherein Tadsorbant Ao and adsorbent Ai each comprise at least one zeolite, said zeolite having at least the following characteristics: 1) Micropore size, determined by liquid nitrogen intrusion, strictly greater than 0.4 nm and less than 0.75 nm, 2) an atomic ratio of Si / Al between 1.4 and 20, inclusive, 3) an accessible volume, measured by water adsorption, strictly greater than 5%, preferably strictly greater than 7%, preferably even more strictly greater than 9% and advantageously strictly less than 35%, advantageously strictly less than 32%.

2. The method according to claim 1, characterized in that it is conducted continuously.

3. A method according to any one of the preceding claims, wherein the wet matrix is ​​a liquid or gaseous matrix comprising an amount of water between 0.1 ppm by volume (ppmv) of water and the water saturation of said matrix, and for example comprising an amount of water between 0.1 ppmv of water and 2000 ppmv of water, preferably between 0.1 ppmv of water and 1000 ppmv of water.

4. A process according to any one of the preceding claims, wherein the wet matrix is ​​a liquid or gaseous matrix selected from natural gas, air, hydrogen, carbon dioxide (CO2), cracked gases, gaseous hydrocarbon cuts, organic liquids, alcohols, organic peroxides and liquefied gases.

5. A method according to any one of the preceding claims, wherein the adsorbent is selected from zeolites, aluminas, silica gels, MOFs, and mixtures of two or more of them.

6. A method according to any one of the preceding claims, wherein the adsorbent Ao and the adsorbent Ai each comprise at least one zeolite, said at least one zeolite being selected from FAU Y type zeolites, with Si / Al molar ratios between 1.4 and 20, preferably between 2.5 and 12, and MFI zeolites with Si / Al molar ratios between 10 and 20, preferably between 10 and 18, and even more preferably between 12 and 16.

7. A process according to any one of the preceding claims, wherein the fraction x of dry matrix recovered in step c) is generally between 70% and 99% by volume, preferably between 80% and 95% by volume.

8. Use of the process according to any one of the preceding claims for drying a liquid or gaseous matrix.

9. Use according to claim 8, wherein the matrix comprises a water content of between 0.1 ppm by volume and the water saturation of said matrix, preferably comprising a water content of between 0.1 ppm by volume and 2000 ppm by volume, preferably further comprising a water content of between 0.1 ppm by volume and 1000 ppm by volume.

10. Use according to claim 8 or claim 9, for drying natural gas, air, hydrogen, carbon dioxide, cracked gases, gaseous hydrocarbon cuts, organic liquids, alcohols, organic peroxides or liquefied gases.

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