Multi-tank adsorber with optimized fluid connections

Abstract

The invention relates to an adsorber for the adsorption separation of a gas mixture, comprising a set of pipes forming flow paths (210) for the feed gas between an outlet (420) of the inlet manifold (400) and the inlet (200) of each of the tanks (100), characterized in that each of the flow paths (210) comprises a bent portion (211, 71, 81, 91) followed by a straight portion (212), the bent portion (211, 71, 81, 91) being a bent portion for redirecting between a direction of flow of the feed gas at the outlet (420) of the inlet manifold (400) and a direction of flow of the feed gas in the straight portion (212), each of the bent portions (211, 71, 81, 91) having a radius of curvature Rc that satisfies, over the entire bent portion (211, 71, 81, 91) between an inlet and an outlet of each of the bent portions, the relationship Rc / Dh ≥ 0.5, preferably Rc / Dh ≥ 1.

Description

Description Title of the invention: Multi-tank adsorber with optimized fluidic connections

[0001] The present invention relates to an adsorber for purifying or separating a gas mixture, said adsorber comprising a set of adsorption tanks installed in parallel between a common inlet manifold and a common outlet manifold by means of a set of pipes arranged to optimize the performance of the adsorber. More specifically, it concerns a layout of the gas flow paths between the inlet and / or outlet of the tanks and the corresponding common manifolds, allowing for the minimization of singular pressure losses for a given dimension in the various pipes.

[0002] Adsorption is widely used to purify or separate gases. Examples include the separation of nitrogen and isoparaffins, the separation of xylenes and alcohols, the production of nitrogen or oxygen from atmospheric air, and the CO2 deballasting of combustion gases and blast furnace gases. On the purification side, applications include dryers, hydrogen and helium purification, methane-rich gas purification, and the adsorption of trace impurities in numerous fluids (mercury removal, NOx, sulfur compounds, etc.).

[0003] Adsorption processes are of several types depending on whether the adsorbent is regenerable in situ or not. We therefore speak of "lost charge" adsorption, meaning that it must be renewed when the product is saturated with impurities (in this case, the term "holding time" is also used to describe such purification), or of adsorption cycles in the other case.

[0004] These adsorption cycles differ primarily in how the adsorbent is regenerated. If regeneration occurs mainly through an increase in temperature, it is a TSA (Temperature Swing Adsorption) process. If, on the other hand, regeneration occurs through a decrease in pressure, it is a PSA (Pressure Swing Adsorption) process. In the latter case, it is common to use more specific names depending on the pressure levels involved.

[0005] VSA processes in which adsorption occurs substantially at atmospheric pressure, preferably between 0.95 and 1.25 bar abs, and the desorption pressure is lower than atmospheric pressure, typically from 50 to 400 mbar abs

[0006] MPSA or VPSA processes in which adsorption takes place at a high pressure above atmospheric pressure, typically between 1.3 and 6 bar abs, or even 10 bar abs, and desorption at a low pressure below atmospheric pressure, generally between 200 and 750 mbar abs

[0007] The PSA processes proper in which the high pressure is substantially greater than atmospheric pressure, typically between 3 and 50 bar abs and the low pressure substantially equal to or greater than atmospheric pressure, generally between 1 and 9 bar abs.

[0008] It is important to note that these various designations (PSA, VSA, VPSA, MPSA) are not standardized and that the limits vary depending on the author. Other designations exist in the literature highlighting specific aspects of the process, such as a rinsing step, recycling, or even the cycle duration.

[0009] It should be noted that the term PSA used in this description encompasses all variants of PSA (including VSA and VPSA). However, when referring to a specific process, the terms VSA or VPSA may be preferred.

[0010] In all these processes, the adsorbent is housed in a reservoir called an adsorber. Various types of adsorbers are used depending on the flow rates and pressures involved, or local economic conditions: vertical cylindrical adsorbers, horizontal cylindrical adsorbers, radial adsorbers, and rectangular adsorbers. Groups of small or medium-sized vertical cylindrical adsorbers are also used in parallel as a replacement for a single, larger adsorber. In this configuration, the adsorber is said to consist of a set of tanks, each with a shell containing an adsorbent mass, an inlet, and an outlet connected to inlet and outlet manifolds common to all the tanks. It may seem paradoxical to want to replace, for example, one adsorber of volume V with four adsorbers of volume V / 4, but a more detailed analysis explains this choice, at least in some cases.The use of small adsorbers (tanks) that can operate in parallel allows for their mass production at reduced costs. In addition to the economies of scale, the relative cost of the tanks, the ease of handling and manufacturing in general, transportation, and the fact that a larger number of workshops equipped to manufacture medium-sized equipment can compete for these costs, all contribute to making the cluster solution often the most economically viable option. Those skilled in the art find other advantages, such as the reduction of dead space at the inlet and outlet of the adsorbers (four hemispherical tanks with a radius r have a volume half that of a single tank with a radius of 2r) or the greater ease of creating horizontal interfaces for the superimposed adsorbent beds.

[0011] However, it is understandable that using several tanks in parallel instead of a single adsorber poses a new problem: the distribution of fluids between the various tanks that should theoretically function in the same way.

[0012] It should be noted that it is relatively easy to distribute a fluid well between several identical tanks and more generally between identical equipment (pipes, exchangers, filters, etc.) either by using a sufficiently large distribution volume, or by implementing the same restriction on all parallel circuits thus creating a pressure drop significantly greater than the pressure difference that may exist from one circuit to another, or finally if the circuits are balanced by suitable devices, for example valves.

[0013] However, all these solutions increase pressure losses and / or dead volumes and therefore have a negative impact on performance.

[0014] The Applicant's French patent FR 11857911 B2 addresses this problem by using an inlet manifold that supplies the various tanks in a perfectly symmetrical manner and an outlet manifold that also discharges these same tanks in a perfectly symmetrical manner. This eliminates the need for additional flow balancing devices between tanks or for enlarging the manifolds, as mentioned above. This solution has already been successfully implemented, but it has nevertheless become apparent that, at least in some cases, the overall performance of the unit can be improved by implementing a more sophisticated flow path design between tanks and common manifolds. This design significantly reduces pressure losses without compromising distribution or dead volumes.

[0015] The invention relates to an adsorber for the separation by adsorption of a gaseous mixture, the adsorber comprising: - a set of at least three adsorption tanks arranged in a configuration for the flow of the gas mixture in the tanks in parallel between said tanks, each of the tanks comprising an inlet and an outlet, - a common inlet manifold, each of the adsorption tanks being fluidly connected to the inlet manifold, the inlet manifold being arranged to supply all the tanks with a feed gas, - a set of pipes forming feed gas circulation channels between an outlet of the inlet manifold and the inlet of each of said tanks, characterized in that each of said circulation channels comprises a bent portion followed by a straight portion, the bent portion being a redirecting bent portion between a feed gas flow direction at the outlet of the inlet manifold and a feed gas flow direction in the straight portion, each of the bent portions having : - a hydraulic diameter Dh, - a gas supply circulation section S, - a radius of curvature Rc measured between a center of the circulation section S and the center of curvature, said measured radius of curvature verifying over the entire angled portion between an entrance and an exit of each of said angled portions the relation Rc / Dh > 0.5, preferably Rc / Dh > 1.

[0016] In particular, the measured radius of curvature verifies over the entire angled portion between an inlet and an outlet of each of the said angled portions the relation Rc / Dh > 1.5, more particularly 1.5 < Rc / Dh < 4 and preferably 1.5 < Rc / Dh < 2.5.

[0017] According to one embodiment, the angled section is a first angled section and each of said traffic lanes comprises a second angled section following the straight section, the second angled section being a redirection angled section between a direction of flow of the feed gas in the straight section and a direction of flow of the feed gas at the inlet of the tank, each of said second angled sections having: - a hydraulic diameter Dh', - a section S' of the supply gas circulation, - a radius of curvature Rc' measured between a center of the circulation section S' and the center of curvature, said measured radius of curvature satisfying over the whole second angled portion between an entrance and an exit of each of said second angled portions the relation Rc' / Dh' > 0.5, preferably Rc' / Dh' > 1.

[0018] In particular, said measured radius of curvature verifies over the whole second angled portion between an inlet and an outlet of each of said second angled portions the relation Rc' / Dh' > 1.5, more particularly 1.5 < Rc' / Dh' < 4 and preferably 1.5 < Rc' / Dh' < 2.5.

[0019] According to one embodiment, each of said traffic lanes comprises a tube of said tube assembly, said tube comprising the straight portion and the angled portion.

[0020] According to one embodiment, said tubing also includes the second angled portion.

[0021] According to one embodiment, each of the pipes comprising the straight portion and the angled portion of each of the traffic lanes is fluidly connected to the outlet of the inlet manifold, in particular at one end of the inlet manifold.

[0022] According to one embodiment, said tubing comprising the straight portion and the angled portion of a traffic lane all have the same geometry.

[0023] According to one embodiment, said tubing comprising the straight portion and the angled portion of each of the flow paths fluidly connects the outlet of the inlet manifold to the inlet of the tank.

[0024] According to one embodiment, said piping comprising the straight portion and the angled portion of each of the flow paths is a so-called main piping, and said piping assembly comprises a plurality of so-called secondary piping fluidly connecting an outlet of each of the main pipings to the inlet of several tanks, each of the secondary pipings comprising an angled portion followed by a straight portion, said angled portion being a redirection angled portion between a flow direction of the feed gas at the outlet of the main piping in question and a flow direction of the feed gas in said straight portion, each of said angled portions having: - a hydraulic diameter Dh”, - a section S” of the supply gas circulation, - a radius of curvature Rc” measured between a center of the circulation section S” and the center of curvature, said measured radius of curvature satisfying over the entire angled portion between an entrance and an exit of each of said angled portions the relation Rc” / Dh” > 0.5, preferably Rc” / Dh” > 1.

[0025] In particular, said measured radius of curvature verifies over the entire angled portion between an inlet and an outlet of each of said angled portions the relation Rc” / Dh” > 1.5, more particularly 1.5 < Rc” / Dh” < 4 and preferably 1.5 < Rc” / Dh” < 2.5.

[0026] According to one embodiment, the adsorber comprises N tubes including the straight portion and the angled portion of each of the traffic lanes, with N greater than or equal to three, adsorber in which each of said N tubes extends in a plane, said planes considered of extension of said N tubes being spaced from each other at an angle equal to 360° divided by N.

[0027] According to one embodiment, the at least three adsorption tanks are arranged in a circle.

[0028] In particular, each of the said planes considered extends perpendicularly to a plane of extension of said circle.

[0029] According to one embodiment, the adsorber comprises a common outlet manifold, each of the adsorption tanks being fluidly connected to the inlet manifold and the outlet manifold, between said manifolds, the outlet manifold being arranged to collect a discharge gas from all the tanks.

[0030] According to one embodiment, the set of pipes forms discharge gas flow paths between the outlet of each of said tanks and an inlet of the outlet manifold, each of said flow paths comprising a straight portion followed by a bent redirection portion between a discharge gas flow direction in the straight portion and a discharge gas flow direction at the inlet of the outlet manifold, each of the bent portions having: - a hydraulic diameter Dh'”, - a section S'" of discharge gas circulation, - a radius of curvature Rc'” measured between a center of the circulation section S'” and the center of curvature, said measured radius of curvature satisfying over the entire angled portion between an entrance and an exit of each of said angled portions the relation Rc”7Dh'” > 0.5, preferably Rc”7Dh'” > 1.

[0031] In particular, said measured radius of curvature verifies over the entire angled portion between an inlet and an outlet of each of said angled portions the relation Rc”7Dh’” > 1.5, more particularly 1.5 < Rc”7Dh’” < 4 and preferably 1.5 < Rc”7Dh’” < 2.5.

[0032] According to one embodiment, the inlet manifold and / or the outlet manifold comprises an inlet and an outlet.

[0033] According to one embodiment, the adsorber comprises a supply line, a purge line and a connection between the inlet manifold, the supply line and the purge line, the supply line together with the inlet manifold connected to it forming a feed gas supply line and the inlet manifold together with the purge line connected to it forming a purge gas supply line from the tanks, said supply line comprising a straight portion followed by a bent redirection portion between a flow direction of the feed gas in the straight portion of the supply line and a flow direction of said feed gas at the outlet of the connection,and / or said purge route comprising a straight portion following a bent redirection portion between a purge gas flow direction at the fitting inlet and a purge gas flow direction in the straight portion of the purge route, each of the bent portions, among the bent portion of, the supply line and / or the angled portion of the purge line, having: - a hydraulic diameter Dh lv , - a traffic section S 1V supply or purge gas, - a radius of curvature Rc lv measured between a center of the traffic section S 1V and the center of curvature, the measured radius of curvature satisfying over the entire angled portion between an inlet and an outlet of each of the said angled portions the relation Rc lv / Dh lv > 0.5, preferably Rc iv / Dh iv > 1.

[0034] In particular, the measured radius of curvature satisfies, over the entire angled portion between an inlet and an outlet of each of said angled portions, the relation Rc lv / Dh lv > 1.5, more specifically 1.5 < Rc lv / Dh lv < 4 and preferably 1.5 < Rc lv / Dh lv < 2.5.

[0035] According to one embodiment, the supply line and the purge line are connected to the inlet of the inlet manifold.

[0036] According to one embodiment, the adsorber comprises a discharge line, an elution line and a junction between the outlet manifold, the discharge line and the elution line, the outlet manifold together with the discharge line connected to it forming a discharge path for the discharge gas and the outlet manifold together with the elution line connected to it forming a supply path for the elution gas to the tanks, said discharge path comprising a straight portion following a bent redirection portion between a flow direction of the discharge gas at the inlet of the junction and a flow direction of the discharge gas in the straight portion of the discharge path,and / or said elution gas supply route comprising a straight portion followed by a bent redirection portion between a flow direction of the elution gas in the straight portion of the elution gas supply route and a flow direction of the elution gas at the outlet of the junction, each of the bent portions, among the bent portion of the discharge route and / or the bent portion of the elution gas supply route, having: - a hydraulic diameter Dh v , - a traffic section S v discharge or elution gas, - a radius of curvature Rc v measured between a center of the traffic section S v and the center of curvature, the measured radius of curvature satisfying over the entire angled portion between an inlet and an outlet of each of the said angled portions the relation Rc v / Dh v > 0.5, preferably Rc v / Dh v > 1.

[0037] In particular, the measured radius of curvature is verified over the entire angled portion between an inlet and an outlet of each of the said angled portions the relation Rc v / Dh v > 1.5, more specifically 1.5 < Rc v / Dh v < 4 and preferably 1.5 < Rc v / Dh v < 2.5.

[0038] According to one embodiment, the discharge line and the elution line are connected to the outlet of the outlet collector.

[0039] According to one embodiment, in which the angled portion of the supply line together with the angled portion of the purge line and / or the angled portion of the discharge line together with the angled portion of the elution gas supply line form one piece of piping or two pieces of piping having a so-called “swallowtail” geometry.

[0040] According to one embodiment, the circulation section S, S', S”, S'”, Siv and / or Sv is circular and the hydraulic diameter is equal to the diameter of said section S, S', S”, S'”, Siv or Sv.

[0041] According to one embodiment, a length L, L', L”, L'”, L 1V and / or L v the straight portion is greater than or equal to twice the hydraulic diameter Dh, Dh', Dh”, Dh'”, Dh lv or Dh v preferably greater than or equal to three times the hydraulic diameter Dh, Dh', Dh”, Dh'”, Dh iv or Dh v .

[0042] According to one embodiment, the adsorber comprises an adsorbent material configured for the separation by adsorption of the gas mixture, each of the tanks comprising a portion of said adsorbent material in the form of an adsorbent ht.

[0043] According to one embodiment, the inlet and outlet of each of the tanks are aligned on an axis of the tank and each of the tanks is configured for axial circulation of the gas mixture through the ht of adsorbent between the inlet and outlet of the tank.

[0044] According to one embodiment, all adsorption tanks are identical.

[0045] According to one embodiment, the adsorber comprises between three and fifteen adsorption tanks, in particular between three and six adsorption tanks.

[0046] The invention also relates to a unit for separating a gaseous mixture by adsorption, the unit comprising at least one adsorber as described above.

[0047] According to one embodiment, the unit includes in particular at least two adsorbers as described above.

[0048] The invention also relates to the use of a unit as described above in an air separation process, in particular a VSA type air separation process by adsorption.

[0049] The invention also relates to a method for separating air by adsorption using a unit as described above, at least one adsorber being subjected to a pressure cycle comprising at least one step of vacuuming the adsorption tanks of at least one adsorber, in particular using a vacuum pump.

[0050] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only to illustrate, but in no way limit, the invention.

[0051] An adsorber according to the invention therefore comprises a set of adsorption tanks arranged in such a configuration that the gas flow always runs in parallel between the different tanks. It should be noted that a set of tanks operating in parallel means that these tanks are equivalent to a single adsorber, and that in the case of a cyclic process with several phases, this remains true throughout the adsorption cycle. In particular, the gas flow circulating during any stage of the adsorption cycle (adsorption, balancing, elution gas supply, purging, etc.) will always flow in parallel between the different tanks forming the adsorber in that stage.This type of operation differs, among other things, from that of a PSAH2 system, where, for example, several adsorbents can be simultaneously in the adsorption stage during a given phase time, and are then said to operate in parallel during that particular phase. However, each of these adsorbents follows the adsorption cycle, with a phase-time lag between them, and therefore has its own independent operating pattern. If we consider the case of adsorbents operating in parallel during adsorption, each of them will subsequently be in different stages from the other adsorbents that were operating in parallel with it.

[0052] It is understood that the arrangement of the piping between tanks and manifolds is one of the main points concerning the installation of the adsorption unit using adsorbers of this type. This is especially true for processes where dead volumes and pressure losses are particularly detrimental to performance. It should be noted that to estimate the pressure loss in a circuit through which a fluid circulates, it is necessary to take into account both the pressure losses due to friction related to the simple regular flow of this fluid in a straight pipe and the so-called "singular" pressure losses related to accidents occurring during this flow (change of direction, bifurcation, junction, change in cross-section, etc.).

[0053] The person skilled in the art must then find, for the unit to be sized, the piping characteristics, in particular the hydraulic diameter corresponding to an optimum between performance (efficiency, productivity, energy consumption...) and investment (cost of piping, its equipment, support, assembly...).

[0054] This approach was in particular carried out during the sizing of the Applicant's first industrial unit, which was built with adsorbers comprising a plurality of tanks operating in parallel.

[0055] A detailed measurement of the pressure drop stacking along the gas flow path in this industrial unit, which was equipped with numerous pressure taps for this purpose, revealed that the pressure drop associated with the separation of gas flows from a manifold to the various tanks, or conversely, with the merging of flows from the tanks into a single manifold, represented a significant portion of the total pressure drop in the circuits. While a simple gas flow circuit design, such as the one adopted at the time of construction of this unit (a unit of average capacity compared to more recent units), may have been justifiable, it has become clear that a more sophisticated piping layout, particularly at these flow separations and merging points, which reduces singular pressure drops and thus energy consumption, is now the preferred solution.Not only can the overall performance / investment balance of the unit be improved - by 1 to a few percent depending on local conditions and the adsorption process implemented - but this also corresponds to the current trend of decreasing energy consumption which is becoming a selection criterion.

[0056] The improvement which is the subject of the present invention arises in part from the fact that there are few or no standard piping elements designed to bring together or separate a plurality of flows with the aim of minimizing pressure losses at a given hydraulic diameter, at least for the industrial diameters which are of interest to us here greater than 0.10 m (DN 4”) and generally well beyond.

[0057] The connections are then generally made on a section of the collector, these connections being generally either distributed along a generatrix parallel to the axis of the collector, or distributed around a circumference of this collector whose diameter is at least locally adapted to this layout. It is this latter layout that was chosen and is the subject of [Fig. 1] Figure 1.

[0058] Figure 1, relating to the Prior Art, shows in its upper part 5 the junction of three traffic lanes, identified as 1, 2, and 3, on a common collector 4. Each of these lanes comprises a straight section 11, 21, and 31. These sections, whose axes lie in the same horizontal plane, are welded to the collector 4 with a constant spacing of 120° between them. The axes of the straight sections and that of the collector are perpendicular. The straight sections continue with redirection bends 12, 22, and 32 to connect each of the The paths are respectively connected to the inlet of the corresponding tank (tanks not shown). The lower section 6 illustrates the junction of this same common manifold 4 with other process-related piping. It should be noted that these are connections of the same type.

[0059] The upper section 5 of [Fig. 1] Figure 1 is particularly simple to construct, employing very standard piping components and some of the easiest welded joints. Furthermore, it has the advantage of being perfectly symmetrical with respect to the three ports. It is also easily adaptable to a number of ports greater than 3.

[0060] The pressure drop measured on-site for a component of this type is significantly higher than that corresponding to a two-way joining / separation using a standard Y-connection, with the same velocity in both the channels and the common manifold. This can be explained by a more abrupt redirection of the flows, transitioning from vertical to horizontal circulation without any transition zone or angle. Furthermore, in the case of joining the flows from the three channels, the flows entering the common manifold tend to collide. It is understandable that this disrupts the hydraulics, creating fluid separation and vortices.

[0061] Following these observations, a study was conducted to optimize the connection of multiple N lines to a common manifold for separating and / or combining the corresponding gas flows, with the aim of reducing pressure losses at constant volume. Custom-designed connection geometries and fittings were developed to redirect the gas flow circulating in the manifold to the various lines leading to the tanks, and conversely, to redirect the gas flow from the tanks circulating in the multiple lines back to the manifold, significantly mitigating the negative effects described above for the original design. It was also verified that these geometries and fittings did not increase the unit's dead volume.

[0062] The common feature of these geometries or parts is that each of the feed gas flow paths between the outlet of the inlet manifold and the inlet of a tank includes an angled portion followed by a straight portion, the angled portion being a redirection angled portion between the flow direction of the feed gas at the outlet of the inlet manifold and the flow direction of the feed gas in the straight portion.

[0063] Figure 2 provides a very schematic illustration of the paragraph above. It shows a single cell 100 of the adsorber, which actually comprises several cells. Typically, this cell has openings at both ends in order to This allows the circulation of various flows through the adsorbent mass (not shown) contained in the tank. Arbitrarily, inlet 200 was placed at the bottom of the tank, and therefore outlet 300 at the other end. Based on this choice, 400 represents the inlet manifold and 500 the outlet manifold, 210 the flow path between the inlet of tank 200 and the inlet manifold 400, and 310 the corresponding outlet path. The connections to the manifolds of the paths originating from the other tanks are symbolically represented by dotted lines. At the opposite end from where the connections with the traffic lanes are made, each collector is itself connected on one side to a supply or elution line and on the other side to a discharge or purge line, respectively a 600 supply line and an 800 purge line for the inlet collector and a 700 elution line and a 900 discharge line for the outlet collector.Each collector has an inlet and an outlet. Arbitrarily considering the case of the gas mixture to be treated circulating from the feed line 600, passing through the tank to produce the least adsorbable fraction as discharge gas, which is then discharged via the discharge line, we have defined the inlet 410 of the inlet collector 400 on the feed line 600 and the purge line 800 side and its outlet 420 on the connection side with the circulation lines (210...) and therefore the inlet 510 of the outlet collector 500 on the connection side with the circulation lines (310...) and its outlet 520 on the elution line 700 and the discharge line 900 side. It should be noted that in the collectors and circulation lines, depending on the stages of the adsorption cycle followed by the adsorber, the gas flows circulate in one direction or the other.

[0064] Also included as part of the flow path 210 connecting the inlet of the tank 200 to the outlet 420 of the inlet manifold is a bent section 211 followed by a straight section 212, the bent section being a redirection bend between a feed gas flow direction at the outlet of the inlet manifold and a feed gas flow direction in the straight section. These elements are the core of the principle of the invention.

[0065] Redirecting the flow through the angled section corrects one of the shortcomings of the original solution. Now, the various flows entering the common collector simultaneously are much less likely to collide. However, an angled section can itself create significant pressure losses depending on the geometry adopted, and it is therefore necessary, in addition to the chosen geometric principle, to define the characteristics of these angled sections.

[0066] A bent section, and more generally any element of piping, can be defined in particular by its curvature, which is generally characterized by the ratio of a The radius of curvature Rc, characteristic of the element in question, is related to the hydraulic diameter Dh of that same element. Depending on the shape of the bent section, its radius of curvature is defined differently. The definitions adopted allow for a continuous description of bent sections ranging from a sharp right-angle change of direction (Rc / Dh = 0) to bends with parallel walls, called rounded bends (0 <Rc / Dh< 0.5), à des coudes à parois concentriques avec des valeurs de Rc / Dh allant de 0.5 à 20 en pratique, sachant qu’il n’y a pas de limite supérieure théorique jusqu’à l’infini qui correspond à une portion droite.

[0067] A sharp bend, formed for example by the 90° connection of 2 straight beveled pipes, will have a radius of curvature equal to 0, and therefore an Rc / Dh ratio also equal to 0.

[0068] For rounded angled portions, Rc generally corresponds to the radius of curvature of the inner wall, that of the outer wall being in practice of the same order of magnitude.

[0069] For angled sections with concentric walls, the radius Rc is that of the oscillating circle to the curve passing through the center of the circulation section at any point of the angled section considered.

[0070] A straight section, by definition, has any radius of curvature measured between a center of the flow section and the center of curvature, which is equal to infinity along that entire section. The ratio Rc / Dh is therefore also theoretically equal to infinity. In practice, due to the flexibility of the pipes and construction tolerances, a pipe assumed to be straight may exhibit a slight bend. Such a geometry does not cause any singular pressure loss, meaning it does not create an obstacle to the flow of gas.

[0071] For the hydraulic diameter, we use the classic definition, which corresponds to the formula Dh = 4A / P, where A is the cross-sectional area of ​​the pipe and P is the wetted perimeter. For a circular pipe, the hydraulic diameter Dh is the inside diameter D of the pipe.

[0072] We usually speak of a small radius curved connecting piece when Rc / Dh <1 or a large radius piece when Rc / Dh > 1.5.

[0073] It can be noted that a change of direction takes place over a shorter distance the lower the Rc / Dh ratio, which is one of the reasons for the existence among suppliers of ranges of elbows of different shapes.

[0074] For circular cross-section pipes, which represent the vast majority of industrially used piping, it is generally possible to find, depending on the supplier, elbows with an Rc / D ratio greater than or equal to 1.5, for example 2.5, 4, 6, or even from Some values ​​are 15 or 20. These are generally rounded values ​​which, for example, for the same external shape, will vary with the pipe wall thickness. Thus, an Rc / D ratio of 1.5 may correspond to more precise values ​​between 1.35 and 1.65. The effect of the Rc / D ratio is very noticeable on singular pressure losses between 0 and 0.5, still noticeable up to 2.5, then its complementary effect on reducing singular pressure losses becomes increasingly limited as the ratio approaches 6. Beyond this value of 6, there is practically no further reduction in singular pressure losses.Furthermore, the length of the flow path in the bend or angled section increases as Rc / Dh increases. Therefore, while adopting such a bend does indeed lengthen the fluid path, an optimum overall pressure loss, including friction losses and singular pressure losses, generally corresponds to the range between 1.5 and 4, or between 1.5 and 2.5 if we limit ourselves to the lower part of the optimal range. At the installation level, without any particular constraints, this lower range of 1.5 / 2.5 will generally be preferred.

[0075] More specifically, by using the principle of the invention for the connections between traffic lanes and collector, it is expected, in comparison to the original part made according to the prior art and having equivalent diameters, to be a reduction in pressure loss of at least 30% for a bent portion of Rc / Dh equal to 0.5, of more than 50% for a bent portion of Rc / Dh of the order of 1.5 and of 70 to 75% for an Rc / Dh of the order of 2.5. This reduction takes into account both the effect of a progressive curvature of the axis of fluid circulation and the less interference between these fluids at the connection.

[0076] For the record, there are bends with slightly more complex geometries than these standard bends, such as bends with guide vanes or bends with sections, but the effects on pressure losses of the Rc / Dh ratio are of the same type.

[0077] To take into account both the type of connection geometry chosen and the appropriate curvature of the flow redirection parts, an adsorber for the adsorption separation of a gaseous mixture includes: - a set of at least three adsorption tanks arranged in a configuration for the flow of the gas mixture in the tanks in parallel between said tanks, each of the tanks comprising an inlet and an outlet, - a common inlet manifold, each of the adsorption tanks being fluidly connected to the inlet manifold, the inlet manifold being arranged to supply all the tanks with a feed gas, - a set of pipes forming feed gas circulation channels between an outlet of the inlet manifold and the inlet of each of said tanks, each of said circulation channels comprising a bent section followed by a straight section, said bent section being a redirecting bent section between a feed gas flow direction at the outlet of the inlet manifold and a feed gas flow direction in the straight section, each of the bent sections having: - a hydraulic diameter Dh, - a gas supply circulation section S, - a radius of curvature Rc measured between a center of the circulation section S and the center of curvature, said radius of curvature measured between an entrance and an exit of each of said angled portions always satisfying the relation Rc / Dh > 0.5, preferably Rc / Dh > 1.

[0078] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of each of said bent portions always satisfies the relation 1.5 < Rc / Dh < 4 and preferably 1.5 < Rc / Dh < 2.5.

[0079] In principle, whenever the space required for an installation with these characteristics is available, a value equal to or greater than 1.5 will be used.

[0080] The word "pipe" is used in the text in a very general way, without referring to a specific section, pipe, manifold, or conduit; these latter terms designate more precise elements in the description. "Portion" and "section" are used interchangeably to refer to a limited piece of piping between two elements, such as an elbow or a fitting.

[0081] It should be noted that, throughout the preceding text, "inlet manifold" and / or "outlet manifold" refer to the "common inlet manifold" and "common outlet manifold," and that the terms "inlet," "outlet," "inlet manifold," "outlet manifold," "feed gas," and "discharge gas" do not structurally limit the adsorber described. These terms are used to name different elements in order to distinguish them from one another, as used in Figure 2. Thus, the terms "inlet," "inlet manifold," "outlet," and "outlet" were chosen to correspond to the circulation of the gas mixture that constitutes the feed gas through the tank and the removal of the least adsorbed fraction. However, this is a geometric representation relative to the configuration of the tank and the adsorber, as gas flows can enter or exit the tank during the cycle through each of these manifolds.The term “feed gas” covers any gas that can be supplied to the adsorber from the collector. considered and this term is not limited to the gaseous mixture constituting the feed gas to be treated in the unit in question.

[0082] Similarly, the term “discharge gas” covers any gas that can be discharged from the adsorber and collected by the relevant collector, and is not limited to the least adsorbed product gas. For example, and without limitation, the least adsorbable fraction produced, the balancing flow, the elution gas, the purge flow, or the product gas containing the most adsorbed fraction are all discharge gases that can be discharged from the tanks via their inlet or outlet and removed by the inlet or outlet collector.

[0083] It should be noted that the gas used for elution is drawn from a first adsorber and introduced into a second adsorber during this elution step: it therefore passes successively through the discharge line of the first adsorber and then through the feed line of the second. The term "elution gas" is preferentially reserved for the gas entering the second adsorber, although this flow can also have other origins. The gas leaving the adsorber during the elution step is called purge gas. It should be noted that the same applies to the balancing flows from one adsorber to another.

[0084] More generally, the adsorber, in addition to the angled portion allowing the redirection of the gas flow from each of the circulation paths towards the central axis of the collector (called the first angled portion), includes for each of these paths a second angled redirection portion between a direction of flow of the feed gas in the straight portion connected to the first angled portion and a direction of flow of the feed gas at the inlet of the tank, each of said second angled portions having: - a hydraulic diameter Dh', - a section S' of the supply gas circulation, - a radius of curvature Rc' measured between a center of the circulation section S' and the center of curvature, said radius of curvature measured between an entrance and an exit of each of said second angled portions always satisfying the relation Rc' / Dh' > 0.5, preferably Rc' / Dh' > 1.

[0085] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of each of said bent portions always satisfies the relation 1.5 < Rc / Dh < 4 and preferably 1.5< Rc' / Dh' < 2.5.

[0086] In principle, whenever the space required for an installation with these characteristics is available, a value equal to or greater than 1.5 will be used.

[0087] It should be noted that these second angled sections do not participate in a flow consolidation or separation, but rather represent a single flow redirection. It is essential to ensure that the entire flow circuit is treated homogeneously and that no avoidable singular pressure losses are created due to abrupt changes in direction, for example, caused by inefficient use of available space.

[0088] Similarly, to eliminate or minimize the need for flow balancing between tanks, which creates additional pressure losses, the chosen layout will favor tubing with flow paths that are as identical as possible. Therefore, an adsorber will be preferred in which the tubing for each tank, fluidly connecting the inlet manifold outlet to the tank inlet, all have the same geometry.

[0089] By same geometry, we mean that, apart from their orientation in space which is specific to each of them, the different tubes are made identically except for construction tolerances.

[0090] Figure 3 gives an example of the application of the invention to an adsorber comprising three tanks operating in parallel connected to a common collector 10 by the three ways marked respectively 7, 8, 9. The tanks are not shown. Each of these channels, starting from the collector 10, has an initial angled redirection section 71, 81, 91 that progressively directs the flow from a vertical direction within the collector to a horizontal direction at the other end of these initial angled sections. Each of these initial angled sections, with identical geometry, has an Rc / D ratio of 1.5, where D is the internal diameter of the circular cross-sectional angled sections. Each of these channels then includes a straight section 72, 88, 92. These sections, whose axes lie in the same horizontal plane, have at their other end a second angled section 73, 83, 93 that progressively redirects the flow in the vertical direction. Each of these second angled sections, with identical geometry, also has an Rc / D ratio of 1.5. In practice, a straight section of tubing (not shown) then connects each of these second angled sections to the inlet of the corresponding tank.To naturally obtain identical flow rates in each of the tanks, the channels 7, 8, and 9, which have identical geometry, have axes in three vertical planes spaced 120° apart, thus ensuring complete central symmetry. This obviously implies that the three tanks constituting the adsorber have their axes on the same circle, with the center of this circle on the axis of the collector.

[0091] The first angled sections of the redirection system 71, 81, and 91 form a custom-made, one-piece connecting piece. This piece is made from three elbows. identical 90° standards with Rc / D equal to 1.5. Each of these elbows is cut identically along a vertical plane to create a notch and is then welded to the two other pieces at the notches to obtain the part marked 20. The advantage of such a part is that it allows direct connection with a manifold of minimum diameter whose cross-section is then on the order of the sum of the cross-sections S of the three elbows so that the variations in traffic speed between lanes 7, 8, 9 and the manifold 10 remain small, thus limiting a potential pressure loss.

[0092] Most of the geometric features of this example can be generalized to a number of tanks N greater than three.

[0093] Thus, an adsorber comprising a plurality of N adsorption tanks operating in parallel, with N greater than or equal to three, comprises N tubing including the straight portion and the angled portion of each of the traffic lanes, each of said N tubing extending in a plane, said planes considered of extension of said N tubing being spaced from each other at an angle equal to 360° divided by N.

[0094] Similarly, the N adsorption tanks are arranged on a circle and each of said planes considered relating to the N tubes extends perpendicularly to an extension plane of said circle.

[0095] More generally, the extension plane of said circle is a horizontal plane, and the extension planes of said tubing are vertical planes. The central axes of the tanks are vertical axes, as are the central axes of the common inlet and outlet manifolds.

[0096] The final layout of the traffic routes from the tanks to the collectors will depend on the site constraints (maximum height, pipe fixing, flexibility) and process type constraints (natural balancing of the different traffic routes, slope and low point in the case of wet gas).

[0097] The simplest design is generally preferred. For example, consider cylindrical tanks with a vertical axis and axial gas flow between the inlet and outlet of a tank; that is, the flow occurs in a vertical direction corresponding to the tank's axis. In most cases, the inlets and outlets are located at the highest or lowest points of the tanks. The flow path, for example, from the tank inlet to the corresponding common manifold, could then consist of a vertical section, a bend to redirect the gas flow into a horizontal section, and another bend to redirect the gas flow towards the central axis of the manifold. This last bend can be directly connected to the collector as shown in Figure 3, or to a straight section itself connected to said collector. Since the collector axis is a priori vertical, it is logical in this case to implement two 90° bends in the traffic lane, corresponding to each of the redirections (vertical-horizontal and horizontal-vertical). However, it would be possible to use 30°, 45°, or 60° bends, for example, if a section of pipe with a slope is used instead of a horizontal one. This could be used on small units with, for example, pipes of 0.10 m diameter or less, or in the case of specific installation constraints.

[0098] Figure 3 shows, as already indicated, a custom-made connecting piece 20 formed from three truncated elbows joined together. This piece is generally the preferred solution and easily adapts to a larger number of tracks. However, beyond six tracks, this embodiment becomes more complex, and other embodiments also conforming to the invention may be preferred.

[0099] Each of the gas flow paths, after redirection along the axis of the manifold, can be independently connected to the end of said manifold. This connection can be made directly at the outlet of the angled section or after adding a straight section extending from each of the angled sections, the other end of said straight sections then being connected to the manifold. Geometrically, this implies a manifold with a slightly larger diameter than that shown in Figure 3, which, depending on the length of the manifold, may be acceptable with respect to dead volumes.

[0100] The end of the collector at which the connections with the different paths are made, assumed to be in the shape of a flat disc in [Fig. 3] figure 3, may have a domed bottom type head of any shape which may facilitate the connection of said paths.

[0101] Another embodiment, when using an adsorber with six or more tanks, is to connect the six (or more) corresponding flow paths in two steps, each step conforming to the principle of the invention. More precisely, these two steps are performed in series. For example, in the case of six tanks and therefore six paths originating from these tanks, these paths can first be joined in pairs to obtain three pipes, thus reducing the situation to the case of [Fig. 3] in Figure 3, where paths 7, 8, and 9 would each correspond to the flow going to or from two tanks. Alternatively, these paths can first be joined in threes, again following [Fig. 3] to obtain two pipes, and then these two pipes can be joined to the common collector for the six tanks.

[0102] Thus, an adsorber will be implemented, in which said tubing, comprising the straight portion and the angled portion for redirecting the gas flow between the flow direction at the manifold outlet and the flow direction in the straight portion, is called the main tubing, and the set of main tubing includes, at the end of each of the straight portions, a plurality of so-called secondary tubing fluidly connecting an outlet of each of the main tubing to the inlet of several tanks, each of the secondary tubing comprising an angled portion followed by a straight portion, said angled portion being an angled portion for redirecting the gas flow between the flow direction at the outlet of the main tubing considered and a flow direction of the feed gas in said straight portion, each of said angled portions having: - a hydraulic diameter Dh”, - a section S” of the supply gas circulation, - a radius of curvature Rc” measured between a center of the circulation section S” and the center of curvature, said radius of curvature measured between an entrance and an exit of each of said angled portions always satisfying the relation Rc” / Dh” > 0.5, preferably Rc” / Dh” > 1.

[0103] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of each of said bent portions always satisfies the relation 1.5 < Rc” / Dh”< 4 and preferably 1.5< Rc” / Dh” < 2.5.

[0104] In principle, whenever the space required for an installation with these characteristics is available, a value equal to or greater than 1.5 will be used.

[0105] In this embodiment, each of the flow paths therefore comprises a main pipe and a secondary pipe. Each of the secondary pipes comprises a bent redirection section followed by a straight section, the various bent sections being located on a circle whose center is a vertical axis passing through the center of the circle on which the adsorption tanks are arranged.

[0106] It should be noted that for a number of tanks N equal to a power of 2, it is theoretically possible to make only 2-to-2 connections in series. This results in complex layouts and normally leads to greater pressure losses and / or higher dead volumes.

[0107] The invention described so far deals very essentially with the input side of the adsorber according to the definition adopted, that is to say more particularly fixes the characteristics to be retained for each of the circulation paths going from the inlet of the tanks to the common inlet collector.

[0108] It is conceivable that an adsorber with multiple tanks operating in parallel can gain in efficiency if the flow paths between its outlet and the outlet manifold have the same characteristics as those used so far for the inlet side. However, the effect of reduced pressure losses on performance may be less significant, and it may be possible to apply the principle of the invention only to the inlet side. Conversely, there may be processes where a reduction in pressure losses will have a predominant impact at the outlet, and where the principle of the invention, adapted to this case, will only be applied to the outlet side of the tanks.

[0109] In general, the following therefore relates to an adsorber comprising more than three adsorption tanks operating in parallel, each of said tanks being fluidly connected to the inlet manifold and the outlet manifold, the outlet manifold being arranged to collect a discharge gas from all the tanks.

[0110] For this adsorber, the set of tubing forms discharge gas flow paths between the outlet of each of said tanks and an inlet of the outlet manifold, each of said flow paths comprising a straight section followed by a bent section for redirection between a discharge gas flow direction in the straight section and a discharge gas flow direction at the outlet manifold inlet, each of the bent sections having: - a hydraulic diameter Dh'”, - a section S'" of discharge gas circulation, - a radius of curvature Rc'” measured between a center of the circulation section S'” and the center of curvature, said radius of curvature measured between an entrance and an exit of each of said angled portions always satisfying the relation Rc”7Dh'” > 0.5, preferably Rc”7Dh'” > 1.

[0111] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of each of said bent portions always satisfies the relation 1.5 < Rc”7Dh’” < 4 and preferably 1.5< Rc”7Dh’” < 2.5.

[0112] In principle, whenever the space required for an installation with these characteristics is available, a value equal to or greater than 1.5 will be used.

[0113] Figure 4 gives a second example of the application of the invention to a The adsorber always comprises three tanks operating in parallel, connected to a common collector 110 by the three paths labeled 17, 18, and 19. The tanks are not shown. Each of these paths, starting from the collector 10, has a first angled redirection section 171, 181, and 191, progressively directing the flow from a vertical direction in the collector to a horizontal direction at the other end of these first angled sections. Each of these first angled sections, of identical geometry, has an Rc / D ratio of 1.5, where D is the internal diameter of the circular cross-section of the angled sections. Each of these paths then includes a straight section 172, 182, and 192. These sections, whose axes lie in the same horizontal plane, have at their other end a second angled section 173, 183, and 193 for progressively redirecting the flow in the vertical direction. Each of these second angled portions of identical geometry also has an Rc / D of 1.5.In practice, a straight section of tubing then connects each of these second angled sections to the outlet of the corresponding tank. To naturally obtain identical flow rates in each tank, the identically shaped channels 17, 18, and 19 have axes in three vertical planes spaced 120° apart, thus ensuring complete central symmetry. This obviously implies that the three tanks constituting the adsorber have their axes on the same circle, with the center of this circle on the axis of the collector.

[0114] The first angled redirection sections 171, 181, and 191 form a custom-made, one-piece connecting piece. This piece is made from three identical standard 90° elbows with an Rc / D ratio of 1.5. Each of these elbows is cut identically along a vertical plane to create a notch and then welded to the other two pieces. In practice, Figure 4 is the outlet-side counterpart of Figure 3. These two piping arrangements belong to the same adsorber. Note that the common outlet manifold, after a straight vertical section 111 connected to the circulation channels, has an angled redirection section 112 with an Rc / D ratio of 1.5, which is itself connected to a straight section 113. The connection of this straight section to the elution and discharge lines is not shown.

[0115] So far, we have mainly referred to the outlet end of the inlet manifold and the inlet end of the outlet manifold. These ends correspond, respectively, to the connections with the flow paths from the inlet and outlet of the tanks. It should be noted that these names derive from the fact that the direction of flow of the gas mixture to be separated was used to identify them.

[0116] In practice, collectors do indeed include an input and an output, that is to say that the inlet collector has an inlet at the opposite end to that of the connection with the traffic lanes (called outlet end) and in the same way the outlet collector has an outlet at the opposite end to that of the connection with the traffic lanes (called inlet end).

[0117] This second end is defined either at the point where the collector in question connects to a process-specific pipe, or possibly in the absence of any connection at the unit boundary, for example at the collector flange located at the unit boundary.

[0118] This second case is not common. It may correspond to a single adsorber with several tanks, used as a holding bed. In operation, it only involves the adsorption / purification stage, with the inlet of the gas mixture to be purified and the outlet of the purified mixture. Besides the possibility of using multiple transportable adsorbers, it is possible, by providing the necessary valves, to change the used adsorbent loads one after the other without having to stop the unit or have a second unit on standby. Since the purification processes often involve pressures close to atmospheric pressure, reducing pressure losses is crucial, and the principle of the invention is therefore particularly advantageous for this type of application.

[0119] In the first, more frequent case, where the common collector connects to one or more process-specific lines, the end of the collector is located at the first connection encountered along the collector from the connections to the traffic lanes. In practice, such a connection is always a double connection with respect to the collector, regardless of the geometry used to make the connection. Figure 2 shows, at its upper part, the common outlet collector 500 connected on one side to an elution line 700 and on the other side to a discharge line 900. These connections are made at the same level, and the outlet end of the collector 520 is logically also located at this level. Each of the two connections has an angled section connected to a straight section.In its lower section, the common inlet manifold 400 is connected on one side to a supply line 600 and on the other to a drain line 800. The inlet of the manifold is fixed at point 420, even though the piping acting as the manifold continues unchanged (same diameter, same direction) as the drain line 800. In this case, only the connection between the manifold 400 and the supply line is made via an angled section connected to a straight section. The choice to fix the inlet of the common manifold at the point of connection with the supply line is logical because it is only from this point that the supply or discharge flows circulate in the piping, alternately according to the cycle of the adsorption unit.

[0120] In practice, according to our conventions, the supply / elution lines and the discharge / purge lines are connected to the inlet of the inlet manifold or to the outlet of the outlet manifold.

[0121] As previously discussed, it is important to note that a feed or elution line, for example 600 or 700 in Figure 2, is not limited to the circulation of the gas mixture to be treated, but rather to any gas that can feed the adsorber from the manifold in question, i.e., both via the inlet and outlet of the tanks. Among the flows that can originate from a feed or elution line, in addition to the gas mixture to be treated, we can mention, but not be limited to, balancing or final recompression flows that repressurize the adsorber, the elution flow from another adsorber, flows related to recycling or rinsing, etc. Similarly, a discharge or purge line will evacuate any gas that can be discharged from the adsorber and collected by the manifold in question, whether it is the inlet or outlet.Among the flows that can be discharged through a discharge or purge line, we can also mention, without limitation, the produced gas corresponding to the least adsorbable fraction, but also the production corresponding to the most adsorbable fraction, the flow resulting from a downward pressure balancing, the gas used for the elution of another adsorber, the residual gas, etc. These flows can be discharged from the tanks via their inlet or outlet and then discharged through the inlet or outlet manifold and subsequently through the associated discharge line. Therefore, for convenience, the terms "feed line" and "elution line" will be used interchangeably, and the terms "purge line" and "discharge line" will be used interchangeably throughout this description.

[0122] All these flows correspond to various stages found in adsorption separation processes. For some of them, the pressure drop resulting from their circulation in pipes, manifolds, and circulation paths has no impact on the unit's performance. Conversely, for others, each additional pressure drop immediately translates into increased energy consumption. Since the aforementioned circuits are common to all these flows, it will very often be advantageous to minimize the pressure drops in the flow circulation circuits. The same approach as previously proposed will then be applied to the piping components in these circuits, namely, implementing very gradual flow redirection methods.

[0123] Thus, an adsorber made according to the principle of the invention and further comprising a supply line, a discharge line and a connection between the collector of inlet, the supply line and the discharge line, the supply line together with the inlet manifold connected to it forming a supply line for the feed gas and the inlet manifold together with the discharge line connected to it forming a discharge line for a gas from the tanks, said supply line comprising a straight portion followed by a bent redirection portion between a flow direction of the feed gas in the straight portion of the supply line and a flow direction of said feed gas at the outlet of the fitting, and / or said discharge line comprising a straight portion followed by a bent redirection portion between a flow direction of the discharge gas at the inlet of the fitting and a flow direction of the discharge gas in the straight portion of the discharge line, said at least one bent portion,among the angled portion of the supply track and / or the angled portion of the discharge track, having: - a Dhiv hydraulic diameter, - a Siv gas supply or discharge circulation section, - a radius of curvature Rciv measured between a center of the circulation section Siv and the center of curvature, said radius of curvature measured between an entry and an exit of said at least angled portion always satisfying the relation Rciv / Dhiv > 0.5, preferably Rciv / Dhiv > 1.0.

[0124] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of said at least one bent portion always satisfies the relation 1.5 < Rciv / Dhiv < 4 and preferably 1.5 < Rciv / Dhiv < 2.5.

[0125] In principle, whenever the space required for an installation with these characteristics is available, a value equal to or greater than 1.5 will be used.

[0126] Similarly, an adsorber constructed according to the principle of the invention and further comprising a supply line, a discharge line, and a connection between the outlet manifold, the supply line, and the discharge line, the supply line together with the outlet manifold connected to it forming a feed gas path, and the outlet manifold together with the discharge line connected to it forming a discharge path for gas from the tanks, said supply path comprising a straight section followed by a redirecting angled section between a flow direction of the feed gas in the straight section of the supply path and a flow direction of said feed gas at the outlet of the connection, and / or said discharge path comprising a straight section following a redirecting angled section between a flow direction of the discharge gas at the inlet of the connection and a direction of discharge gas flow in the straight portion of the discharge track, said at least one angled portion, among the angled portion of the supply track and / or the angled portion of the discharge track, having: - a hydraulic diameter Dhv, - a flow section Sv of the discharge or elution gas, - a radius of curvature Rev measured between a center of the circulation section Sv and the center of curvature, said radius of curvature of said at least one angled portion always satisfying the relation Rcv / Dhv > 0.5, preferably Rcv / Dhv > 1.0.

[0127] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of said at least one bent portion always satisfies the relation 1.5 < Rc / Dh < 4 and preferably 1.5 < Rcv / Dhv < 2.5.

[0128] In principle, whenever the space required for an installation with these characteristics is available, a value equal to or greater than 1.5 will be used.

[0129] Therefore, when the supply line and the discharge line separate simultaneously from a common collector, inlet and / or outlet, thus geometrically creating a passage from one lane to two lanes and vice versa, it will possibly be possible to use for this purpose one (or two) pieces of commercial piping of the type commonly called a “swallowtail” or sometimes an “improved Y” chosen to verify the relationship Rc / Dh > 1.0, preferably Rc / Dh > 1.5. These pieces generally constitute three pipes of the same diameter, these pipes being here the collector, the supply line, the discharge line.

[0130] The lower part of [Fig. 3] figure 3 shows a dovetail piece 23 of Rc / D equal to 1.5 for each of the two angled portions of identical geometry 24 and 25, the ends of which are each connected to a straight section, respectively 26 and 27.

[0131] If one of the supply or discharge pipes has a diameter significantly smaller than the diameter of the manifold, it is possible to custom-make a part in which each of the connections to the common manifold will have an angled section connected to a straight section, each of the angled sections being chosen to verify the relationship Rc / Dh > 1.0, preferably Rc / Dh > 1.5. There is no need here to list the potential assembly methods, but the simplest is to connect the angled section of small diameter to the angled section of larger diameter, the cutting planes and the resulting notches being adapted to the geometry.

[0132] The primary objective of the invention is to limit the pressure losses in an adsorber comprising a plurality of tanks operating in parallel without increasing their dead volumes. Analysis of pressure measurements at numerous points in an operating industrial unit has shown that the significant impact of flow joining and separation points on the total pressure loss is due to these connections. The core of the invention therefore focuses on improving the hydraulics of these connections, as well as the associated piping and manifolds. It is understood that, in addition to the connections, a person skilled in the art, having followed the proposed improvement principles, will address all the circuits for which minimizing pressure loss is critical, using their expertise.

[0133] For example, it will be necessary, whenever possible, to include a sufficient straight section at the ends of any bend to ensure that the traffic flow has a velocity profile corresponding to a steady state. This is particularly important for traffic lanes connected to the inlets or outlets of tanks, where a good natural distribution of traffic flow between these lanes is expected.

[0134] Thus, we will preferentially implement an adsorber in which a length L, L', L”, L'”, Liv and / or Lv of the straight portion is greater than or equal to 3 times the hydraulic diameter Dh, Dh', Dh”, Dh'”, Dhiv or Dhv preferably greater than or equal to 5 times the hydraulic diameter Dh, Dh', Dh”, Dh'”, Dhiv or Dhv.

[0135] In cases where the unit's location does not allow these lengths to be respected, it will be necessary to assess the benefit of inserting equipment into the piping, for example, cross-packed sections, allowing for a faster restoration of a regular velocity profile.

[0136] Similarly, in the event of a change in cross-section, the use of a diffuser can be considered, as well as, more rarely, the use of an angled cross-section with internal vanes to better channel the circulating flow.

[0137] Conversely, in circuits where a pressure loss would have no negative effect, for example in a circuit with a relaxation of the circulating flow, it would probably be relevant to use T-type meetings or separations which are logically of lower cost.

[0138] In the description, the adsorber comprises a plurality N of cells, with N > 3, each having an inlet and an outlet for flow circulation. Although one could imagine cells in the form of a horizontal cylinder, or even with internals allowing radial circulation through the adsorbent mass, the main advantage of the multi-cell adsorber solution lies in the use of cylindrical cells. vertical axis. The simplicity of construction, the cost, the ease of obtaining good gas distribution through the adsorbent mass and the fact of being able to superimpose several layers of adsorbents of different nature without the implementation of complex internals mean that it is hardly envisaged to use other types of tanks except in very particular circumstances such as the case of treatment of very large flow rates (several hundred thousand m3 / h) requiring the parallel implementation of at least three radial adsorbers which would then be connected according to the invention.

[0139] In general, the adsorber comprises an adsorbent material configured for the separation by adsorption of the gas mixture, each of the tanks comprising a portion of said adsorbent material in the form of an adsorbent ht, said ht being able to comprise several layers of adsorbent of different nature.

[0140] It is recalled that in the preferred implementation, the inlet and outlet of each of the adsorber tanks are aligned on the axis of the tank and each of the tanks is configured for axial circulation of the gas mixture through the ht of adsorbent between the inlet and outlet of the tank.

[0141] Similarly, and preferably: - all the adsorption tanks of the adsorber are identical, - The adsorber comprises between three and fifteen adsorption tanks, - and / or each of the adsorption tanks has a diameter between 0.25 and 6m, preferably between 0.5 and 3m.

[0142] It should be noted that the optimization between the number N of cells and the diameter De of the cells will depend largely on the acceptable pressure drop in the adsorbent bed, the volume of adsorbent Va required in the adsorber being fixed by the process. The height of the adsorbent bed Ha in the cell results from these choices, knowing that all these parameters are related by the formula: Va = N*(n.Dc) A 2 / 4)*Ha and allow us to determine the pressure loss through the tank.

[0143] The invention also relates to a unit for separating a gaseous mixture by adsorption, the unit comprising at least one adsorber as described.

[0144] As mentioned above, the use of the invention in a unit comprising a single adsorber will generally correspond to a unit of the total loss treatment type dealing with large flow rates of low pressure feed gas.

[0145] Generally, said unit comprises at least two adsorbers according to the invention.

[0146] In practice, the principle of the invention can be applied to the vast majority of gas mixture separation units by adsorption. Given the primary objective The aim of minimizing pressure losses in the case of a multi-tank adsorber is to apply this principle preferentially to units also dealing with large flow rates of charge gas at low pressure, in particular if the adsorbent mass includes more than two adsorbents of different nature, in which case the radial adsorber solution which also allows for the treatment of large flow rates with reduced pressure losses is very difficult to consider.

[0147] In particular, the adsorption unit can be implemented in a CO2 capture, flue gas cleaning or air cleaning process of type TSA or PSA, the term PSA here covering the processes of PSA proper, VPSA and VS A.

[0148] The adsorption unit is implemented in an air separation process, in particular an air separation process by adsorption of type V SA or VPSA.

[0149] The invention relates to a method of separating air by adsorption implementing a unit comprising at least one adsorber as described, the at least one adsorber being subjected to a pressure cycle comprising at least one step of evacuating the adsorption tanks of the at least one adsorber, in particular using a vacuum pump.

[0150] It also relates to a process for purifying or separating a TSA type gas mixture in which the regeneration gas is at low pressure, i.e. close to atmospheric pressure (<1.2 bar abs) or under vacuum.

Claims

Demands

1. An adsorber for the separation by adsorption of a gaseous mixture, the adsorber comprising: - a set of at least three adsorption tanks (100) arranged in a configuration of gas mixture flow in the tanks (100) in parallel between said tanks, each of the tanks (100) comprising an inlet (200) and an outlet (300), - a common inlet manifold (400, 10), each of the adsorption tanks (100) being fluidly connected to the inlet manifold (400, 10), the inlet manifold (400, 10) being arranged to supply all the tanks with a feed gas, - a set of pipes forming flow paths (210, 7, 8, 9) for the feed gas between an outlet of the inlet manifold (400, 10) and the inlet of each of said tanks (100), characterized in that each of said flow paths (210, 7, 8, 9) comprises a bent section (211, 71, 81, 91) followed by a straight section (212, 72, 88, 92), the bent section (211, 71, 81, 91) being a redirection bend between a flow direction of the feed gas at the outlet (420) of the inlet manifold (400, 10) and a flow direction of the feed gas in the straight section, each of the bent sections (211, 71, 81, 91) having: - a hydraulic diameter Dh, - a gas supply circulation section S, - a radius of curvature Rc measured between a center of the circulation section S and the center of curvature, said measured radius of curvature satisfying over the entire angled portion (211, 71, 81, 91) between an entrance and an exit of each of said angled portions (211, 71, 81, 91) the relation Rc / Dh > 0.5, preferably Rc / Dh > 1.

2. Adsorber according to the preceding claim, wherein said measured radius of curvature satisfies over the entire bent portion (211, 71, 81, 91) between an inlet and an outlet of each of said bent portions the relation Rc / Dh > 1.5, more particularly 1.5 < Rc / Dh < 4 and preferably 1.5 < Rc / Dh < 2.

5.

3. Adsorber according to any one of the preceding claims, wherein the angled portion (211, 71, 81, 91) is a first angled portion and each of said traffic lanes (210, 7, 8, 9) comprises a second angled portion (73, 83, 93) following the straight section (212, 72, 88, 92), the second angled section (73, 83, 93) being a redirection angled section between a direction of flow of the feed gas in the straight section (212, 72, 88, 92) and a direction of flow of the feed gas at the inlet (200) of the tank, each of said second angled sections (73, 83, 93) having: - a hydraulic diameter Dh', - a section S' of the supply gas circulation, - a radius of curvature Rc' measured between a center of the circulation section S' and the center of curvature, said measured radius of curvature satisfying over the whole of the second angled portion (73, 83, 93) between an entrance and an exit of each of said second angled portions the relation Rc' / Dh' > 0.5, preferably Rc' / Dh' > 1.

4. Adsorber according to any one of the preceding claims, wherein each of said traffic paths (210, 7, 8, 9) comprises a tube of said tube assembly, said tube comprising the straight portion (212, 72, 88, 92) and the angled portion (211, 71, 81, 91).

5. Adsorber according to claim 3 in combination with claim 4, wherein said tubing also includes the second bent portion (73, 83, 93).

6. Adsorber according to any one of claims 4 or 5, wherein said tubing comprising the straight portion (212, 72, 88, 92) and the angled portion (211, 71, 81, 91) of a traffic lane (210, 7, 8, 9) all have the same geometry.

7. Adsorber according to any one of claims 4 to 6, wherein said tubing comprising the straight portion (212, 72, 88, 92) and the angled portion (211, 71, 81, 91) of each of the flow paths (210, 7, 8, 9) is a said main tubing and said tubing assembly comprises a plurality of said secondary tubing fluidly connecting an outlet of each of the main tubing to the inlet of several tanks (100), each of the secondary tubing comprising an angled portion followed by a straight portion, said angled portion being a redirection angled portion between a feed gas flow direction at the outlet of the main tubing considered and a feed gas flow direction in said straight portion, each of said angled portions having: - a hydraulic diameter Dh”, - a section S” of the supply gas circulation, - a radius of curvature Rc” measured between a center of the circulation section S” and the center of curvature, said measured radius of curvature satisfying over the entire angled portion between an entrance and an exit of each of said angled portions the relation Rc'7Dh” > 0.5, preferably Rc” / Dh” > 1.

8. Adsorber according to any one of claims 4 to 7, comprising N tubes including the straight portion (212, 72, 88, 92) and the angled portion (211, 71, 81, 91) of each of the traffic lanes (210, 7, 8, 9), with N greater than or equal to three, adsorber in which each of said N tubes extends in a plane, said planes considered of extension of said N tubes being spaced from each other at an angle equal to 360° divided by N.

9. Adsorber according to any one of the preceding claims, comprising a common outlet manifold (500), each of the adsorption tanks being fluidly connected to the inlet manifold (400) and the outlet manifold (500), between said manifolds, the outlet manifold (500) being arranged to collect a discharge gas from all the tanks.

10. An adsorber according to any one of the preceding claims in combination with claim 9, wherein the tubing assembly forms discharge gas flow paths (310, 17, 18, 19) between the outlet (300) of each of said tanks and an inlet (510) of the outlet manifold, each of said flow paths (310, 17, 18, 19) comprising a straight portion (172, 182, 192) followed by a bent portion (171, 181, 191) for redirecting between a discharge gas flow direction in the straight portion (172, 182, 192) and a discharge gas flow direction at the inlet (510) of the outlet manifold (500), each of the bent portions (171, 181, 191) having: - a hydraulic diameter Dh'”, - a section S'" of discharge gas circulation, - a radius of curvature Rc'” measured between a center of the circulation section S'” and the center of curvature, said measured radius of curvature satisfying over the entire angled portion (171, 181, 191) between an entrance and an exit of each of said angled portions (171, 181, 191) the relation Rc”7Dh”’ > 0.5 , preferably Rc”7Dh”’ > 1.

11. An adsorber according to any one of the preceding claims comprising, a supply line (600), a purge line (800) and a fitting between the inlet manifold, the supply line (600) and the purge line (800), the supply line (600) together with the inlet manifold (400) connected thereto forming a feed gas supply line and the inlet manifold (400) together with the purge line (800) connected thereto forming a purge gas supply line from the tanks (100), said supply line comprising a straight portion followed by a bent redirection portion between a flow direction of the feed gas in the straight portion of the supply line and a flow direction of said feed gas at the outlet of the fitting,and / or said purge route comprising a straight portion following a bent redirection portion between a purge gas flow direction at the fitting inlet and a purge gas flow direction in the straight portion of the purge route, each of the bent portions, among the bent portion of the supply route and / or the bent portion of the purge route, having: - a Dhiv hydraulic diameter, - a Siv circulation section for the supply or purge gas, - a radius of curvature Rciv measured between a center of the circulation section Siv and the center of curvature, said measured radius of curvature verifying over the entire angled portion between an entrance and an exit of each of said angled portions the relation Rciv / Dhiv > 0.5, preferably Rciv / Dhiv > 1.

12. An adsorber according to any one of the preceding claims comprising a discharge line (900), an elution line (700), and a junction between the outlet manifold (500), the discharge line (900), and the elution line (700), the outlet manifold (500) together with the discharge line (900) connected to it forming a discharge path for the discharge gas, and the outlet manifold (500) together with the elution line (700) connected to it forming a supply path for the elution gas to the tanks (100), said discharge path comprising a straight portion following a redirecting angled portion between a discharge gas flow direction at the inlet of the junction and a discharge gas flow direction in the straight portion of the discharge path, and / or said elution gas supply path comprising a straight portion followed by a angled redirection portion between a flow direction of the elution gas in the straight portion of the elution gas supply line and a flow direction of the elution gas at the outlet of the junction, each of the angled portions, among the angled portion of the discharge line and / or the angled portion of the elution gas supply line, having: - a hydraulic diameter Dhv, - a flow section Sv of the discharge or elution gas, - a radius of curvature Rev measured between a center of the circulation section Sv and the center of curvature, said measured radius of curvature satisfying over the entire angled portion between an inlet and an outlet of each of said angled portions the relation Rcv / Dhv > 0.5, preferably Rcv / Dhv > 1.

13. A gas mixture separation unit by adsorption, the unit comprising at least one adsorber according to one of the preceding claims.

14. Use of a unit according to claim 13 in an air separation process, in particular a VSA type adsorption air separation process.

15. A method for separating air by adsorption employing a unit according to claim 13, the at least one adsorber being subjected to a pressure cycle comprising at least one step of evacuating the adsorption tanks of the at least one adsorber, in particular using a vacuum pump.

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