Multi-tank adsorber with optimized fluidic connections

Abstract

Adsorber for the separation by adsorption of a gas mixture comprising a set of tubes forming flow paths (210) for the feed gas between an outlet (420) of the inlet manifold (400) and the inlet (200) of each of said tanks (100), characterized in that each of said 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 redirection bend between a flow direction of the feed gas at the outlet (420) of the inlet manifold (400) and a flow direction of the feed gas in the straight portion (212), each of the bent portions (211, 71, 81, 91) having a radius of curvature Rc measured between a center of the cross-section of circulation S and the center of curvature, said measured radius of curvature verifying over the entire angled portion (211, 71, 81,91) between an inlet and an outlet of each of the said angled portions the relation Rc / Dh ≥ 0.5, preferably Rc / Dh ≥ 1. Abbreviated figure: Fig. 3,

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 gaseous 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, the purification of methane-rich gases, 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, i.e., adsorption that must be renewed when the product is saturated with impurities (in this case, the term "guard bed" 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 give more specific names depending on the pressure levels involved:

[0005] VSA processes in which adsorption takes place 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 greater than 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 should be noted that these various designations (PSA, VSA, VPSA, MPSA) are not standardized and that the limits vary depending on the authors. 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 use of the term PSA in the description here covers all variants of PSA (including VSA and VPSA). However, when referring to a specific process, the terms VSA or VPSA may be used preferentially.

[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 adsorber, horizontal cylindrical adsorber, radial adsorber, and parallelepiped adsorber. Assemblies of small or medium-sized vertical cylindrical adsorbers are also used in parallel as a replacement for a single, larger adsorber. In this case, the adsorber is said to consist of a set of tanks, each comprising a shell containing an adsorbent mass, an inlet, and an outlet connected to inlet and outlet manifolds common to all of 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 a number of 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, 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 of radius r have a volume half that of a single tank of radius 2r) or the greater ease of creating horizontal interfaces for the superimposed adsorbent beds.

[0011] However, it is understood that the use of several tanks in parallel instead of a single adsorber poses a new problem, that of the distribution of fluids between the various tanks which must a priori operate 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 differences 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, thus avoiding 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 it is possible, at least in certain cases, to improve the overall performance of the unit by implementing a more sophisticated flow path design between tanks and common manifolds. This design then makes it possible to significantly reduce 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 section followed by a straight section, the 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 measured radius of curvature verifying over the entire angled portion between an inlet and an outlet of each of said angled portions the relation Rc / Dh > 0.5, preferably Rc / Dh > 1.

[0016] In particular, said measured radius of curvature verifies over the entire bent portion 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.

[0017] According to one embodiment, the angled portion is a first angled portion and each of said traffic lanes comprises a second angled portion following the straight portion, the second angled portion being a redirection angled portion between a direction of flow of the feed gas in the straight 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 measured radius of curvature verifying over the whole second angled portion between an inlet and an outlet of each of said second angled portions the relation Rc7 Dh' > 0.5, preferably Rc' / Dh' > 1.

[0018] In particular, said measured radius of curvature verifies over the whole second bent portion between an inlet and an outlet of each of said second bent 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 to 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 tubing comprising the straight portion and the angled portion of each of the flow paths is a so-called main tubing and said assembly of tubing comprises 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 a redirection angled portion between a flow direction of the feed gas 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 flow cross-section S” of the feed gas, - 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 inlet and an outlet of each of said angled portions the relation Rc” / Dh” > 0.5, preferably Rc'VDh” > 1.

[0025] In particular, said measured radius of curvature verifies over the entire bent portion between an inlet and an outlet of each of said bent portions the relation Rc'7 Dh” > 1.5, more particularly 1.5 < Rc” / Dh” < 4 and preferably 1.5 < Rc'VDh” <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 said planes considered extends perpendicularly to an extension plane 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 tubes forms discharge gas circulation channels between the outlet of each of said tanks and an inlet of the collector of the outlet, each of said traffic lanes 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 inlet of the outlet manifold, 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 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”7 Dh’” > 1.5, more particularly 1.5 < Rc”7Dh”’ < 4 and preferably 1.5 < Rc”7 Dh’” <2.5.

[0032] According to one embodiment, the input collector and / or the output collector comprises an input and an output.

[0033] According to one embodiment, the adsorber comprises a supply line, a purge line and a fitting 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 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 Dhlv hydraulic diameter, - a S1V circulation section for the supply or purge gas, - a radius of curvature Rclv measured between a center of the circulation section S1V and the center of curvature, said measured radius of curvature verifying over the entire angled portion between an inlet and an outlet of each of said angled portions the relation Rclv / Dhlv > 0.5, preferably Rclv / Dhlv > 1.

[0034] In particular, said measured radius of curvature verifies over the entire bent portion between an inlet and an outlet of each of said bent portions the relation Rclv / Dhlv > 1.5, more particularly 1.5 < Rclv / Dhlv < 4 and preferably 1.5 < Rclv / Dhlv < 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 Dhv, - a flow section Sv of the discharge or elution gas, - a radius of curvature Rcv 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 entrance and an exit of each of said angled portions the relation Rc7Dhv > 0.5, preferably Rcv / Dhv > 1.

[0037] In particular, said measured radius of curvature verifies over the entire bent portion between an inlet and an outlet of each of said bent portions the relation Rc7Dhv > 1.5, more particularly 1.5 < Rc7Dhv < 4 and preferably 1.5 < Rc7Dhv < 2.5.

[0038] According to one embodiment, wherein 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 or two pieces of piping having a so-called “swallowtail” geometry.

[0039] 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.

[0040] According to one embodiment, a length L, L', L”, L' ”, L1V and / or Lv of the straight portion is greater than or equal to twice the hydraulic diameter Dh, Dh', Dh”, Dh'”, Dhlv or Dhv preferably greater than or equal to three times the hydraulic diameter Dh, Dh', Dh”, Dh'”, Dhiv or Dhv.

[0041] 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 bed.

[0042] 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 adsorbent bed between the inlet and outlet of the tank.

[0043] According to one embodiment, all the adsorption tanks are identical.

[0044] According to one embodiment, the adsorber comprises between three and fifteen tanks adsorption, in particular between three and six adsorption tanks.

[0045] The invention also relates to a unit for separating a gaseous mixture by adsorption, the unit comprising at least one adsorber as described above.

[0046] The invention also relates to the use of a unit as described above in an air separation process, in particular an air separation process by adsorption of type VS A.

[0047] The invention also relates to a method of separating air by adsorption implementing 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.

[0048] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only by way of illustration and in no way limit the invention.

[0049] An adsorber according to the invention therefore comprises a set of adsorption tanks arranged in such a configuration that the gas flows always run 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 comprising several phases, this remains true throughout the adsorption cycle. In particular, the gas flow circulating during The flow from any stage of the adsorption cycle (adsorption, balancing, elution gas supply, purging, etc.) will always occur in parallel between the different cells forming the adsorber in that stage. This type of operation differs from that of a PSA H2 system, where, for example, several adsorbers can be simultaneously in the adsorption stage during a given phase time, and are also said to operate in parallel during that particular phase. However, each of these adsorbers follows the adsorption cycle, with a phase-time lag between them, and therefore has its own independent operation. If we consider the case of adsorbers operating in parallel during adsorption, each of them will subsequently be in different stages from the other adsorbers that were operating in parallel with it.

[0050] 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 of a circuit in 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.).

[0051] 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, their equipment, support, assembly...).

[0052] This approach was in particular carried out during the sizing of the Applicant's first industrial unit made with adsorbers comprising a plurality of tanks operating in parallel.

[0053] During the detailed measurement of the pressure drop stacking along the gas flow path in this industrial unit, which was equipped for this purpose with numerous pressure taps, it was observed that the pressure drop related to the separation of gas flows from a manifold to the various tanks, or conversely, to 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 design of the gas flow circuits, such as the one adopted at the time, could be justified when this unit was built—a unit of average capacity compared to more recent units—it became apparent that a more sophisticated piping layout, particularly at these flow separations and merging points, would allow for a reduction in pressure drop. Addressing singular pressure losses and thus energy consumption now proved to be a preferred solution. Not only can the overall performance / investment ratio 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.

[0054] 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.

[0055] The connections are then generally made on a section of the collector, said connections generally being either distributed along a generatrix parallel to the axis of the collector, or distributed over a circumference of this collector whose diameter is at least locally adapted to this arrangement. It is this latter arrangement that was chosen and that is the subject of [Fig. 1].

[0056] Fig. 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 elbows 12, 22, and 32 to connect each lane respectively with the inlet of the corresponding tank (tanks not shown). The lower part 6 illustrates the junction of this same common collector 4 with other piping related to the process. It should be noted that these are connections of the same type.

[0057] The upper part 5 of [Fig. 1] [Fig. 1] is particularly simple to manufacture because it uses very standard piping components and welded joints that are among the easiest to make. Furthermore, it has the advantage of being perfectly symmetrical with respect to the 3 ports. It is also easy to adapt to a number of ports greater than 3.

[0058] The pressure drop measured on site for a component of this type is significantly higher than that corresponding to a 2-way joining / separation using a standard Y-connection, at the same speed in the channels and the common collector. This can be explained by a more abrupt redirection of the flows, passing here from vertical to horizontal circulation without a transition zone or angle. Furthermore, in the case of joining the flows from the 3 channels, the flows entering the common collector tend to collide. It is understood that The hydraulics are disrupted, with the creation of fluid vein separations and vortices.

[0059] Following these observations, a study was conducted to optimize the connection of a plurality of N channels to a common manifold for separating and / or combining the corresponding gas flows, with the aim of reducing pressure losses at constant volume. Connection geometries and custom-made connecting parts were designed to redirect, under improved conditions, the gas flow circulating in the manifold to the various channels leading to the tanks, and conversely, to redirect the gas flows from the tanks circulating in the plurality of corresponding channels back to the manifold, significantly limiting the negative effects described above for the original device. It was also verified that these geometries and parts did not increase the dead volume of the unit.

[0060] 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.

[0061] Figure 2 provides a very schematic illustration of the above paragraph. A single tank 100 of the adsorber is shown, although it actually comprises several tanks. Typically, this tank has openings at both ends to allow the circulation of various flows through the adsorbent mass (not shown) contained within the tank. Arbitrarily, the inlet 200 has been placed at the bottom of the tank, and therefore the outlet 300 at the other end. Consequently, 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 dashed lines.At the end opposite the connections to the circulation lines, each manifold is itself connected on one side to a feed or elution line and on the other side to a discharge or purge line, respectively a feed line 600 and a purge line 800 for the inlet manifold and an elution line 700 and a discharge line 900 for the outlet manifold. Each manifold has one inlet and one outlet. Arbitrarily assuming 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, the inlet 410 of the inlet manifold 400 is defined as being on the feed line 600 side. and purge 800 and its outlet 420 on the connection side with the circulation paths (210...) and therefore the inlet 510 of the outlet manifold 500 on the connection side with the circulation paths (310...) and its outlet 520 on the elution 700 and discharge 900 side. It is recalled that in the manifolds and the circulation paths, according to the stages of the adsorption cycle that the adsorber follows, the gas flows circulate in one direction or the other.

[0062] Also shown as belonging to 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 flow direction of the feed gas at the outlet of the inlet manifold and a flow direction of the feed gas in the straight section. These elements are the core of the principle of the invention.

[0063] 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.

[0064] A bend, and more generally any pipe element, can be defined in particular by its curvature, which is generally characterized by the ratio of a characteristic radius of curvature Rc of the element in question to the hydraulic diameter Dh of that same element. Depending on the shape of the bend, its radius of curvature is defined differently. The definitions adopted allow for a continuous description of bends ranging from a sharp right-angle change of direction (Rc / Dh = 0) to parallel-walled bends, 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.

[0065] 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 a ratio Rc / Dh also equal to 0.

[0066] 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.

[0067] For angled portions with concentric walls, the radius Rc is that of the osculating circle to the curve passing through the center of the circulation section at any point of the angled portion considered.

[0068] By definition, a straight section has any radius of curvature measured between a center of the flow section and the center of curvature, which is equal to infinity along the entire length of said 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, that is, it does not create an obstacle to the flow of gas.

[0069] For the hydraulic diameter, the classic definition is used, 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.

[0070] It is customary to speak of a curved connecting piece of small radius when Rc / Dh <1 or of large radius when Rc / Dh >1.5.

[0071] It may 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.

[0072] For circular cross-section pipes, which represent the vast majority of industrially used pipes, 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 15 or 20 for some. These values ​​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 first part of the optimal range. At the installation level, without any particular constraints, this lower 1.5 / 2.5 range will generally be preferred.

[0073] More specifically, by using the principle of the invention for the connections between traffic lanes and the collector, it is expected, compared to the original part manufactured according to the Prior Art and having equivalent diameters, that there will be a reduction in pressure loss of at least 30% for a bent section with an Rc / Dh ratio of 0.5, more than 50% for a bent section with an Rc / Dh ratio of approximately 1.5, and 70% at 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 fluid circulation axis and the less interference between these fluids at the connection level.

[0074] For the record, there are bends with slightly more complex geometries than these standard bends such as, for example, bends with guide vanes or bends with sections, but the effects on pressure losses of the Rc / Dh ratio are of the same type.

[0075] To take into account both the type of connection geometry selected and the appropriate curvature of the flow redirection parts, an adsorber for the separation by adsorption of a gaseous mixture comprises: - 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.

[0076] 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.

[0077] A priori, whenever the space necessary for an installation presenting these latter characteristics is available, a value equal to or greater than 1.5 will be retained.

[0078] The word piping is used in the text in a very general way without referring to a particular section, pipe, manifold or conduit, the latter terms designating more precise elements in the description. indifferently portion or section to talk about a limited piece of piping between 2 elements such as an elbow, a connection.

[0079] It should be noted that, in all the foregoing, “inlet manifold” and / or “outlet manifold” should be understood as “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 claimed adsorber. These are terms used to name different elements in order to distinguish them from one another as used for [Fig. 2]. Thus, the terms "inlet", "inlet manifold" and "outlet", "outlet manifold" were chosen to correspond to the circulation of the gas mixture that constitutes the feed gas through the tank and to the evacuation of the least adsorbed fraction, but this is a geometric reference in relation to the configuration of the tank and the adsorber, of the gas flows that 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 in question, and this term is not limited to the gas mixture constituting the feed gas to be treated in the unit in question.

[0080] Similarly, the term “discharge gas” covers any gas that can be discharged from the adsorber and collected by the collector in question, and this term is not limited to the least adsorbed product gas. For example, and without limitation, the production of the least adsorbable fraction, the flow from an equilibration, the gas used for elution, the purge flow, or the product gas containing the most adsorbed fraction... are discharge gases that can be discharged from the tanks through their inlet or outlet to be evacuated by the inlet or outlet collector.

[0081] It should be noted that the gas used to perform 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.

[0082] More generally, the adsorber, in addition to the angled portion allowing the gas flow of each of the circulation paths to be redirected in the direction of the central axis of the collector, referred to as the first angled portion, comprises 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.

[0083] 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.

[0084] A priori, whenever the space necessary for an installation presenting these latter characteristics is available, a value equal to or greater than 1.5 will be retained.

[0085] It should be noted that the aforementioned second angled sections do not participate in a current union or separation, but rather constitute a single flow redirection. It is important to ensure here that the entire flow circuit is treated homogeneously and that no avoidable singular pressure losses are created that would be linked to abrupt changes of direction, for example, caused by poor use of available space.

[0086] Similarly, in order to eliminate or limit the means of balancing the flow between tanks, which create additional pressure losses, the chosen layout will favor tubing with flow paths that are as identical as possible. Thus, an adsorber will be preferred in which the tubing for each tank, fluidly connecting the outlet of the inlet manifold to the inlet of the tank, all have the same geometry.

[0087] 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.

[0088] 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 paths designated 7, 8, 9 respectively. The tanks are not shown. Each of these paths has, starting from the collector 10, a first angled redirection section 71, 81, 91 progressively directing the flow from a vertical direction in the collector to a horizontal direction at the other end of said first angled sections. Each of these first angled sections, of identical geometry, has an Rc / D of 1.5, where D is the inside diameter of the circular cross-sectional angled sections. Each of these paths then includes a straight section 72, 88, 92. These sections, whose axes are in the same horizontal plane, have at their other end a second angled section 73, 83, 93 progressively redirecting the flow. 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 tank, the identically shaped channels 7, 8, and 9 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.

[0089] The first angled redirection sections 71, 81, 91 here form a custom-made, one-piece connecting piece. This piece is made from three identical standard 90° bends with an Rc / D ratio of 1.5. Each of these bends is cut identically along a vertical plane to create a notch and is then welded to the other two pieces at the notches to obtain the piece designated 20. The advantage of such a piece is that it allows for a direct connection with a collector of minimum diameter, the cross-section of which is then on the order of the sum of the cross-sections S of the three bends, so that the variations in traffic speed between lanes 7, 8, 9 and the collector 10 remain small, thus limiting any potential pressure loss.

[0090] Most of the geometric features of this example can be generalized to a number of tanks N greater than three.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] The final layout of the traffic routes from the tanks to the collectors will depend on the installation constraints (maximum height, fixing of the pipes, flexibility...) and process type constraints (natural balancing of the different traffic routes, slope and low point in the case of wet gas...).

[0095] The simplest design is generally preferred. For example, let us assume cylindrical tanks with a vertical axis and an axial flow of gases between the inlet and outlet of a tank; that is to say, the flow occurs in a vertical direction corresponding to that of 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 inlet of a tank to the corresponding common manifold, may then successively comprise a vertical section, a bend allowing the gas flow to be redirected into a horizontal section, and a bend allowing the gas flow to be redirected in the direction of the manifold's central axis. This last bend can be directly connected to the manifold as shown in [Fig. 3] [Fig. 3] or to a straight section which is itself connected to said manifold.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 the pipe section is not horizontal but has a slope. This could be used on small units with, for example, pipes of 0.10 m diameter or less, or in cases of specific installation constraints.

[0096] Fig. 3 shows, as already indicated, a connecting piece 20 manufactured at This design is created from three truncated elbows joined together. This component is generally the preferred solution and easily adapts to a larger number of tracks. However, beyond six tracks, this design becomes more complex, and other embodiments also conforming to the invention may be preferred.

[0097] 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 [Fig. 3], which, depending on the length of the manifold, may be acceptable with respect to dead volumes.

[0098] The end of the collector at which the connections with the different paths are made, assumed to be in the form of a flat disc in [Fig.3] [Fig.3], may include a domed bottom type head of any shape which may facilitate the connection of said paths.

[0099] Another embodiment in the presence of an adsorber comprising six or more tanks is to connect the six—or more—ways of The corresponding circulation occurs in two stages, each stage conforming to the principle of the invention. More precisely, these two stages are carried out sequentially. For example, in the case of six tanks and therefore six outlets from these tanks, these outlets can first be combined in pairs to obtain three pipes, thus reducing the system to the case of [Fig. 3] [Fig. 3], in which outlets 7, 8, and 9 would each correspond to the flow going to or from two tanks. Alternatively, these outlets can first be combined in threes, again following [Fig. 3] [Fig. 3], to obtain two pipes, and then these two pipes can be joined to the manifold common to the six tanks.

[0100] 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 outlet of the manifold and the flow direction in the straight portion, is a so-called main tubing, and the set of main tubing comprises, 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'VDh” > 1.

[0101] 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'VDh” < 2.5.

[0102] A priori, whenever the space necessary for an installation presenting these latter characteristics is available, a value equal to or greater than 1.5 will be retained.

[0103] 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.

[0104] 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.

[0105] The invention described so far deals very essentially with the inlet 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.

[0106] It is understood that an adsorber comprising a plurality of tanks operating in parallel can gain in efficiency if the flow paths between its outlet and the outlet manifold have the same type of characteristics as those used so far for the inlet side. However, the effect of a reduction in pressure losses may be less significant on performance, and it may be possible to apply the principle of the invention only on 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 on the outlet side of the tanks.

[0107] In general, the following therefore relates to an adsorber comprising more than 3 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.

[0108] For this adsorber, the assembly 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 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 radius of curvature measured between an inlet and an outlet of each of said angled portions always satisfying the relation Rc”7Dh’” > 0.5, preferably Rc”7 Dh’” > 1.

[0109] According to a preferred embodiment, the radius of curvature measured between an inlet and an outlet of each of said angled portions always satisfies relation 1.5 <Rc”7Dh”’ < 4 et de préférence 1.5<Rc”7Dh’” <2.5.

[0110] A priori, whenever the space necessary for an installation presenting these latter characteristics is available, a value equal to or greater than 1.5 will be retained.

[0111] Figure 4 provides a second example of the application of the invention to an adsorber, again comprising three tanks operating in parallel, connected to a common collector 110 by the three paths designated 17, 18, and 19. The tanks are not shown. Each of these paths, starting from the collector 10, has a first bent 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 said first bent sections. Each of these first bent sections, of identical geometry, has an Rc / D ratio of 1.5, where D is the inside diameter of the circular cross-section of the bent sections. Each of these routes then includes a straight section 172, 182, 192. These sections, whose axes are in the same horizontal plane, have at their other end a second angled section 173, 183, 193 for the progressive redirection of 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 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 said circle on the axis of the collector.

[0112] The first angled redirection sections 171, 181, 191 here 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 joined 130 by welding to the other two pieces. In practice, [Fig. 4] [Fig. 4] is the outlet-side counterpart of [Fig. 3] [Fig. 3]. These two piping arrangements belong to the same adsorber. It should be noted that the common outlet collector includes, after a straight vertical section 111 connected to the traffic lanes, a bent redirection section 112, with an Rc / D equal to 1.5, itself connected to a straight section 113. The connection of this last straight section with the elution and discharge pipes is not shown.

[0113] Up to this point, the outlet end of the inlet manifold and the inlet end of the outlet manifold have been the most frequently cited terms. These ends correspond respectively to the connections with the traffic lanes originating from the inlet and the exit from the tanks. It is worth noting that the names come from the fact that the direction of flow of the gas mixture to be separated was used to identify them.

[0114] In practice, the collectors do indeed include an inlet and an outlet, 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).

[0115] This second end is defined either at the point where the collector in question connects to a process-specific conduit, or possibly in the absence of any connection at the unit limit, for example at the collector flange located at the unit limit.

[0116] This second case is not common. It may correspond to the case of a single adsorber with several tanks, used as a holding bed. In operation, it only includes the adsorption / purification stage with the inlet of the gaseous mixture to be purified and the outlet of the purified mixture. In addition to 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.

[0117] In the first, more frequent case mentioned, where the common collector connects to one or more process-specific lines, the end of said 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 this 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 comprises 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 manifold inlet 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 common manifold inlet at the point of connection with the supply line is logical because it is only from this point that the fluid circulates. the piping the supply or discharge flows, alternately according to the cycle of the adsorption unit.

[0118] 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.

[0119] As previously discussed, it should be noted that a feed or elution line, for example 600 or 700 on [Fig. 2], is not limited to the circulation of the gas mixture to be treated, but rather to any gas that may feed the adsorber from the collector in question, i.e., both via the inlet and outlet of the tanks. Among the flows that may 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 may be discharged from the adsorber and collected by the collector in question, whether it is an inlet or outlet gas.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, 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.

[0120] 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 elements in these circuits, namely, implementing very gradual flow redirection methods.

[0121] 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 inlet manifold, 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 redirecting elbow 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 redirecting elbow 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 elbow 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.

[0122] 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.

[0123] A priori, whenever the space necessary for an installation presenting these latter characteristics is available, a value equal to or greater than 1.5 will be retained.

[0124] Similarly, an adsorber made 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 supply line for the feed gas and the outlet manifold together with the discharge line connected to it forming a discharge line for a gas coming 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 discharge route comprising a straight section following a bent redirection section between a discharge gas flow direction at the inlet of the connection and a discharge gas flow direction in the straight section of the route, discharge, 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.

[0125] 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.

[0126] A priori, whenever the space necessary for an installation presenting these latter characteristics is available, a value equal to or greater than 1.5 will be retained.

[0127] Therefore, when the supply line and the discharge line separate simultaneously from a common inlet and / or outlet collector, 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.

[0128] The lower part of [Fig.3] [Fig.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.

[0129] If one of the supply or discharge pipes has a diameter substantially 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 portion connected to a straight portion, each of the angled portions 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 portion of small diameter to the angled portion of larger diameter, the cutting planes and the resulting notches being adapted to the geometry.

[0130] The primary object of the invention is to limit the pressure losses of an adsorber comprising a plurality of tanks operating in parallel without increasing their dead volumes. Analysis of pressure measurements at a large number of points in an operating industrial unit showed that the significant weight of the meetings and flow separations in the total pressure loss. The core of the invention therefore relates to improving the hydraulics of these connections, the associated pipes, and manifolds. It is understood that, in addition to the connections, a person skilled in the art, having followed the proposed improvement principles, will treat all the circuits for which it is important to minimize pressure loss, using their expertise.

[0131] For example, it will be necessary, whenever possible, to adopt a sufficient straight length at the ends of a curved section so that the flow in circulation has a velocity profile corresponding to a steady state. This is all the more important at the level of the traffic lanes connected to the inlets or outlets of the tanks, since a good natural distribution of flows between these lanes is relied upon.

[0132] Thus, an adsorber will preferably be implemented 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.

[0133] In cases where the installation of the unit does not allow these lengths to be respected, it will be necessary to evaluate the benefit of inserting into the piping equipment, for example, cross-packing sections, allowing a regular velocity profile to be restored more quickly.

[0134] 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.

[0135] Conversely, on circuits where a pressure loss would have no negative effect, for example on 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.

[0136] In the description, the adsorber comprises a plurality N of tanks with N>3, each having an inlet and an outlet for the flow circulation. Although one can imagine tanks in the form of a horizontally oriented cylinder, or even with internals allowing radial circulation through the adsorbent mass, the main advantage of the multi-tank adsorber solution lies in the use of vertically oriented cylindrical tanks.The simplicity of implementation, the cost, the ease of obtaining good gas distribution through the adsorbent mass, and the ability to superimpose several layers of adsorbents of different nature without the implementation of complex internals mean that the use of other types of tanks is hardly considered except in very specific circumstances, such as the case of processing very large flow rates (several hundred thousand m3 / h) requiring the parallel implementation of at least 3 radial adsorbers which would then be connected according to the invention.

[0137] Generally, 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 bed, said bed being able to comprise several layers of adsorbent of a different nature.

[0138] It is recalled that in the preferred embodiment, 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 adsorbent bed between the inlet and outlet of the tank.

[0139] Similarly, preferably: - all 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.

[0140] It should be noted that the optimization between the number N of tanks and the diameter De of the tanks will depend largely on the acceptable pressure drop in the adsorbent bed, the volume of adsorbent Va required to be housed in the adsorber being fixed by the process. The height of the adsorbent bed Ha in the tank results from these choices, given that all these parameters are related by the formula: Va = N*(n;.DcA2 / 4)*Ha and allow the pressure drop across the tank to be determined.

[0141] The invention also relates to a unit for separating a gaseous mixture by adsorption, the unit comprising at least one adsorber as described.

[0142] 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.

[0143] Generally, said unit comprises at least two adsorbers according to the invention.

[0144] 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 of minimizing pressure losses in the case of a multi-tank adsorber, said principle will preferentially apply to units also processing large flow rates of feed gas at low pressure, in particular if the adsorbent mass comprises more than two adsorbents of different natures, in which case the radial adsorber solution, which also allows for the processing of large flow rates with reduced pressure losses, is very difficult to implement.

[0145] In particular, the adsorption unit may 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.

[0146] The adsorption unit is implemented in an air separation process, in particular an air separation process by adsorption of type VS A or VPSA.

[0147] 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.

[0148] 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 for the flow of the gaseous mixture 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 tubing 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 traffic lanes (210, 7, 8, 9) comprises a curved portion (211, 71, 81, 91) followed by a straight portion (212, 72, 88, 92), the curved portion (211, 71, 81,91) being a bent redirection section between a feed gas flow direction at the outlet (420) of the inlet manifold (400, 10) and a feed gas flow direction in the straight section, each of the bent sections (211, 71, 81, 91) having: - a hydraulic diameter Dh, - a feed gas circulation cross-section S, - a radius of curvature Rc measured between a center of the circulation cross-section S and the center of curvature, said measured radius of curvature satisfying over the entire bent section (211, 71, 81, 91) between an inlet and an outlet of each of said bent sections (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. An 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 section (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 flow cross-section S' of the feed gas, - a radius of curvature Rc' measured between a center of the flow cross-section S' and the center of curvature, said measured radius of curvature satisfying over the entire second angled section (73, 83, 93) between an inlet and an outlet of each of said second angled sections 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. An 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 fluidically 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 gas flow direction supply in said straight portion, each of said bent portions having: - a hydraulic diameter Dh”, - a circulation section S” of the supply gas, - 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 bent portion between an inlet and an outlet of each of said bent portions the relation Rc” / Dh” > 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 the flow 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 circulation section S”' of the discharge gas, - a radius of curvature Rc”' measured between a center of the circulation section S’” and the center of curvature,

11.

12. said measured radius of curvature verifying over the entire angled portion (171, 181, 191) between an inlet and an outlet of each of said angled portions (171, 181, 191) the relation Rc”7Dh”' > 0.5 , preferably Rc”7Dh’” > 1. 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 line 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 line, each of the bent portions, among the bent portion of the supply line and / or the bent portion of the purge line, having: - a hydraulic diameter Dhiv, - a circulation cross-section Siv of the supply or purge gas, - a radius of curvature Rciv measured between a center of the circulation cross-section Siv and the center of curvature, said measured radius of curvature satisfying over the entire bent portion between an inlet and an outlet of each of said bent portions the relation Rciv / Dhiv > 0.5, preferably Rciv / Dhiv > 1. 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

13.

14.

15. the tanks (100), said discharge channel comprising a straight portion following a bent redirection portion between a discharge gas flow direction at the junction inlet and a discharge gas flow direction in the straight portion of the discharge channel, and / or said elution gas supply channel comprising a straight portion followed by a bent redirection portion between an elution gas flow direction in the straight portion of the elution gas supply channel and an elution gas flow direction at the junction outlet, each of the bent portions, among the bent portion of the discharge channel and / or the bent portion of the elution gas supply channel, having: - a hydraulic diameter Dhv, - a circulation cross-section Sv of the discharge or elution gas, - a radius of curvature Rev measured between a center of the circulation cross-section Sv and the center of curvature, said measured radius of curvature verifying 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. A gaseous mixture separation unit, the unit comprising at least one adsorber according to one of the preceding claims. Use of a unit according to claim 13 in an air separation process, in particular a VS A type air separation process by adsorption. Air separation process by adsorption employing a unit according to claim 13, at least one adsorber being subjected to a pressure cycle comprising at least one step of evacuating the adsorption tanks of at least one adsorber, in particular using a vacuum pump.

Images