SE537166C2 - Systems for the management of nitrous oxide collected from exhaled air - Google Patents

Abstract

A B S T R A C TA system for I) collecting nitrous oXide in eXhalation air, and ll) delivering nitrous oXidecollected in (I) to further processing,5 characterized in comprising a pool of one or several mutually replaceable adsorption units(201) each of Which contains a nitrous oXide reversible adsorbents (213a) and having:i) an inlet port (214a) for eXhalation air,ii) an outlet port (214b) for discharging processed eXhalation air depleted in nitrous oXide,iii) an inlet port (215a) for a desorbing gas, and10 iv) an outlet port (215b) for discharging desorbing gas plus nitrous oXide, together With A) a docking arrangement (202) Which is associated With adsorption of nitrous oXide andcomprises:a) a connection (2l9a) for connecting the outlet port OLmaSk (212) to the inlet port (214a), 15 andb) optionally a connection (219b) for connecting a Waste recipient (205) to the outlet port(214b), and B) a docking arrangement (202) Which is associated With desorption of nitrous oXide and comprises:20 a) a connection (220a) for connecting a source for desorbing gas to the inlet port (215a)and b) a connection (220b) for connecting the outlet port (215b) to the inlet port (217).

Description

1SYSTEM TECHNICAL FIELD The present relates to a system for collecting nitrous oXide in air eXhaled (= eXhalation air) byone or more individuals and subsequently delivering the nitrous oXide to an apparatus forfurther processing. The invention comprises the system as such, a method of using it, an adsorption unit containing a reversible nitrous oXide adsorbent, and a pool of these units.

BACKGROUND TECHNOLOGY Nitrous oXide is an air pollutant Which is considered at least 300 times more effective thancarbon dioxide as a “green house gas”. The gas is considered hazardous for people exposed toit during Work (e. g. doctors, dentists, nurses etc). Occupational health limits have been set to25 ppm. Cost-effective and convenient apparatuses, systems and methods for reducing discharge of the gas to the atmosphere are likely to be imperative in the future.

Within health care units, nitrous oXide is used Within surgery, dental care, matemity careduring delivery etc due to its anaesthetic and analgesic effects. The patient is allowed toinhale a gas miXture (= inhalation air) in Which the main components are nitrous oxide,typically in concentrations 2 10%, such as 2 20% and/or 2 80%, such as 2 70 % (v/v) andoXygen. The relative composition of nitrous oXide and oXygen is essentially the same forinhalation air and eXhalation air but the level of moisture (HZO) and carbon dioXide isincreased in eXhalation air compared to inhalation air. When an enhanced anaesthetic effect isdesired, the miXture also contains a gaseous anaesthetic agent, as a rule in concentrations 210%, such as 2 5% or less 2 2 % With typically levels being in the range of 0.25-3 %, suchas 0.5-2 % (v/v). Suitable anaesthetic agents have been selected amongst volatile halo-containing organic compounds, e. g. halo-containing hydrocarbons, halo-containing ethers etc,and other volatile or gaseous organic compounds Which are capable of eXerting an anaesthetic effect, for instance anaesthetic hydrocarbons not containing halo substituents.

At larger health care units eXhalation air containing nitrous oXide is typically handled in aWaste gas handling system Which is common for several rooms/patients. In these systems theexhaled air is typically diluted With ambient air (e.g. 10-5 0 times) and finally treated at the health care unit for removal of nitrous oXide and/or passed into ambient atmosphere.

Apparatuses and methods for the handling of eXhaled air containing nitrous oXide at larger 2health care units have been discussed in DE 42087521 (Carl Heyer GmbH), DE 4308940 (Carl Heyer GmbH), GB 2059934 (Kuraray), US 7,235 ,222 (ShoWa Denko KK), JP publ No.55-031463 (Kuraray Co Ltd), JP publ No. 56-011067 (Kuraray Co Ltd), JP publ No.2006230795 (Asahi Kasei Chemicals Corp), US 4,259,303 (Kuraray Co., Ltd), WO20101071538 (Nordic Gas Cleaning AB), WO 2006059606 (ShoWa Denko KK), WO2002026355 (ShoWa Denko KK), WO 2006124578 (Anaesthetic Gas Reclamation LLC), JP publ No. 55-031463 (Kuraray Co Ltd), JP publ No. 56-011067 (Kuraray Co Ltd), JP publ No. 2006230795 (Asahi Kasei Chemicals Corp).

See also PCT/SE20010/000292 and Swedish patent application 10010932 (= US SN61/414683) (both of Nordic Gas Cleaning AB), EP 0284277 (Union Carbide) and EP 136840(Siemens-Elema AB).

An experimental study on adsorption of nitrous oXide in ventilation air by the use of zeolits isgiven in “Removal of laaghing gas from air by the use of zeolites” IVL commission for Stockholms Lans Landsting, vavvxfvnsllse: Report 2007-03-08.

The publications given above are mainly focusing on removal of nitrous oXide by catalytic decomposition, adsorption or compression/condensation.

At smaller health care units and/or during minor treatments requirin g short-time inhalation ofnitrous oXide it is neither cost effective nor convenient to use the equipments used for largerunits. For smaller units and minor treatments it becomes inconvenient and expensive With a common system for handling and/or decomposition of Waste anaesthetic gases. The levels of nitrous oXide to deal With Will be inherently higher Which is associated With its own problems.

Previously suggested apparatuses and methods for use at smaller units and/or during minortreatments have typically been adapted for use close to a patient and in many cases they arebased on adsorption; see for instance WO 2009095601, WO 2009095605 and WO2009095611 (all of Air Liquid). See also US 3941573 (Chapel) and US 5928411(DragerWerk). Typical smaller health care units and minor treatments are e. g. ambulances, dentists, private doctors, local health centres, acute clinics etc.

See also Removal of laaghing gas from air at dentists by the use of zeolites” Stockholms lans landsting SSL - Occupational Health, xvvtfxvzsilse: Report 2010-06-10: “ There is a need for more cost-effective and convenient systems and methods for collectingnitrous oXide from eXhaled air of single patients at health care units and subsequent furtherprocessing of nitrous oXide to environmentally acceptable end products. These systems shoulda) be adapted for use close to a patient, b) be flexible and simple to manufacture and use, c)support favourable total energy balance, d) support discharge of acceptable levels of harmful substances to the environment (e. g. nitrous oXide and NOX (X = 1 och/eller 2)) etc.

All patents and patent applications cited in this specification are hereby incorporated in their entirety by reference.

OBJ ECTSThe main object of the invention comprises to provide convenient and cost effective systems and methods for handling of nitrous oXide collected from eXhaled air as discussed above.

DRAWINGS Figure 1 illustrates an adsorption unit to be used in the system. The unit has two separate inletports and two separate outlet ports, i.e. in total four ports.

Figure 2 illustrates a system which comprises mobile adsorption units with only two portsand docking arrangements comprising sensors (scales) for measuring amount ofnitrous oXide caught in the unit. In figure 2a the adsorption unit is connected to aface mask for inhaling nitrous oXide (adsorption mode). In Fig 2b the sameadsorption unit connected to an apparatus for further processing of nitrous oXide(desorption mode).

Figure 3 illustrates a mobile adsorption unit having only two ports and temperature sensorsfor measuring amount of nitrous oXide caught in the unit.

Flow directions are indicated with arrows (in fig 1 with > for adsorption and >> for desorption). Reference numerals in the figures comprise three digits. The first digit refers to the number of the figure and the second and third digits to the specific item. Corresponding items in different figures have as a rule the same second and third digits. Figure 3 represents modes considered to be the most advantageous at the filing date. See also preferred variants discussed below.

INVENTION 5 4The inventor has realized that the objects given above can be met for systems and methods generally defined under Technical Field by including a pool of one, two or more through-flow nitrous oXide adsorption units (101,201,301) which are mutually replaceable if there are two or more them in the pool, together with A) a docking arrangement DAadS (202) for connecting an adsorption unit (201) of the pool toa) the face mask (204) used by an individual eXhaling nitrous oXide, and b) to a wasterecipient (205) for eXhaled air proces sed in the unit (i.e. depleted with respect to nitrousoXide) , and B) a docking arrangement DAdeS (203) for connecting an adsorption unit (201) of the pool toa) a source for a desorbing gas (206), and b) an apparatus (207) for further processing ofnitrous oXide, and C) optionally a measuring arrangement comprising one or more sensors (208a,b,308a,b,c) formeasuring the amount of nitrous oXide caught in an adsorption unit (301), and D) optionally a logging arrangement (309a+b) with a memory (310a+b) for storing datareflecting Working efficiency for at least the latest time of use for the individual adsorption units (101,201,301) of the pool,.

The eXpression “for connecting” means both “is connecting” and “is capable of beingconnected”. The connection may be direct or indirect where indirect includes via afunctionality, e. g. via valves, heaters, flow changing functions, filters etc and direct means viasimple connections and/or extension conduits without any particular functionality other than transportation of gas/fluid. This applies if not otherwise indicated.

The eXpression “mutually replaceable” means that corresponding parts of individualadsorption units of the pool have the same geometrical fit for the system, e. g. with respect togeometry of inlet ports and outlet ports, connections to docking arrangements, connections tosensors etc. It also means that the individual adsorption units are mobile between a dockingarrangement DAadS and a docking arrangement DAdeS, i.e. between different possible locationsof individuals inhaling nitrous oXide and/or between such a location and an apparatus forfurther processing of nitrous oXide. Corresponding definition also applies to dockingarrangements for variants of the inventive system comprising several DAabS and/or several DAdes- The eXpression “further processing” encompasses e.g. decomposition, pooling, storing and the 5like. Pooling and/or storing are possibly combined with condensation/compression/ fractionation. There are a number known apparatus and methods for performing furtherprocessing; see the publications discussed above and recently filed SE 1130018-3 (filedMarch 24, 2011) (Nordic Gas Cleaning AB).

The first aspect of the invention is a system for carrying out a method comprising the steps of:I) collecting nitrous oXide in air eXhaled by an individual inhaling/exhaling nitrous oXidevia a facemask (204), andll) delivering the nitrous oXide collected in step (I) to an apparatus (207) for further processing of nitrous oXide collected in step I. lnhalation/eXhalation of nitrous oXide is done via a face mask arrangement (204) (further oncalled “face mask”) which comprises an inlet lLmaSk (211) for inhalation and an outlet OLmaSk(212) for eXhalation plus the face mask as such together with various arrangements supportingand facilitatin g undisturbed breathing when the mask is used. The velocity for eXhaled airleaving a face mask arrangement is typically within the interval of 15-40 L/min, such as 20-30 L/min.

The main characteristic feature is that the system comprises a pool containing one, two ormore adsorption units together with arrangements A +B, preferably combined with C and/or D.

THE POOL OF ADSORPTION UNITS ln addition to nitrous oXide adsorption units the pool may also contain other adsorption units,e. g. for adsorbing anaesthetic agents, moisture etc. The term “adsorption unit” will further ononly refer to “mobile and mutually replaceable and reversible nitrous oXide adsorption units", if not otherwise indicated by the context.

An adsorption unit (101,201,301) has a through-flow adsorption chamber (113,213,313)which contains a through-flow nitrous oXide reversible adsorbent (1 13a,213a,3 la) placed inthe chamber leaving a gap (113b,c,213b,c,313b,c) devoid of adsorbent at each end of thechamber. The unit also has: i) An inlet port lPadS (114a,214a,314a) for inlet of an adsorption flow containing eXhalation air, i.e. nitrous oXide. This port is connectable to an outlet port OLmaSk (212) of a face 6mask arrangement (204). The connection may be direct or indirect.

An outlet port OPadS (114b,214b,314b) for outlet of the adsorption flow. The flow eXitingthis port is depleted in nitrous oXide. It is discharged to a waste recipient (205). Thewaste recipient may be ambient atmosphere. This port is in preferred variants directlyconnectable to ambient atmosphere (redundant connection). In other variants theconnection to ambient atmosphere is indirect via functionalities as illustrated below.iii) An inlet port lPdeS (115a,215a,315a) for inlet of a desorption flow which contains adesorbing gas (purge gas). The port is connectable to a source for desorbing gas (206).This source is preferably ambient atmosphere or may alternatively be in the form of astorage container containing e. g. pressurized air, pressurized nitrogen etc. The sourcemay include an arrangement for pre-processing the desorbing gas, e. g. a heater, a flowchanging function, a drier etc. In other words this port may be directly or indirectlyconnectable to the actual source as such.iv) An outlet port OPdeS (115b,215b,315b) for outlet of the desorption flow. This flowreleases (= desorbs) nitrous oXide from the adsorbent and thus contains nitrous wheneXiting this port contains nitrous oxide. The port is directly or indirectly connectable tothe inlet port lPapp (217) of an apparatus (207) for further processing of nitrous oXide desorbed from adsorption units of the pool.

The inlet port IPadS (114a,214a,314a) and the outlet port OPadS (115b,215b,315b) of a unitdefine the flow direction Flowads of the adsorption flow through the chamber/unit/adsorbent.The two ports are placed at opposite ends/parts of the chamber/unit/adsorbent and accordingly define an upstream end/part and a downstream end/part in relation to the adsorption flow.

The inlet port IPdeS (115a,215a,315a) and the outlet port OPdeS (114b,214b,314b) of the unitdefine the flow direction Flowdes for the desorption flow in relation to the chamber/unit/adsorbent. The two ports are placed at opposite ends/parts of the chamber/unit/adsorbent andaccordingly define an up stream end/part and a downstream end/part in relation to the desorption flow.

The flow directions Flowads and Flowdes may have the same or opposite directions. The inletports IPadS and IPdeS (114a,214a,314a and 115a,215a,315a) for the adsorption flow and thedesorption flow, respectively, may be i) at opposite ends or ii) at the same end of the chamber/unit/adsorbent, where (i) means opposite directions for the flows and (ii) the same 7direction for the flows. The same applies for the outlet ports OPadS and OPdeS (114b,214b, 314b and 115b,215b,315b). A convenient arrangement is that ports pair-wise coincide, e. g. a) oQQosite flow directions: inlet port lPadS (114a,214a,314a) with outlet port OPdeS(115b,215b,315b), and/or outlet port OPadS (114b,214b,314b) with inlet port IPdeS(115a,215a,315a) with preference “and”, and b) same flow direction: inlet ports lPadS (114a,214a,314a) with IPdeS (115a,215a,315a), and/oroutlet ports OPadS (114b,214b, 314b) with OPdeS (115b,215b,315b) with preference for “ “and' '.

The directions of the two flows in space can be Vertical or horizontal. Vertical directions arepreferred and include a) vertically upwards with an angle between the flow direction and thevertical line being within i 45° preferably 0°, and b) vertically downwards with a corresponding interval of 180° i 45 °, preferably 180°. Intervals of the same widths are valid for downwardly and upwardly directed horizontal flows.

For adsorption/desorption under flow conditions in general it is considered to be optimal toreverse the flow direction when switching from adsorption to desorption. This principle alsoapplies to adsorption/desorption in the present invention. However, the construction of thesystem of the invention might be simpler, more convenient. more cost-effective etc to usewith the same flow direction for adsorption and desorption if the adsorption unit isconstructed as illustrated in figure 3 (coinciding inlet ports, coinciding inlet conduits etc); see below under the heading Desorption part of the flow regulating arrangement.

The gaps/empty spaces (113b,c,213b,c,313b,c) cover the ends the adsorbent in order tosupport even distribution of adsorption flow/exhalation air and/or desorbing flow/ gas throughthe adsorbent (113,a,213a,313a). When placed at an upstream end the gap is an example of adistributor function and placed at a downstream end it is an example of a collector function.As illustrated in figure 3, the gap/empty space (313c) next to an inlet port IPdeS (315a) for the desorption flow may in preferred variants contain a heating function ().

The adsorption unit may also comprise an inlet conduit (116a,216a,316a,117a,217a,317a) foreach inlet port (114a,214a,314a,115a,215a,315a) and/or an outlet conduit (116b,216b,316b,117b,217b,317b) for each outlet port (114b,214b,314b, 115b,215b,315b) for gas flow communication between the chamber and the inlet ports and the outlet ports, respectively. 8These conduits may coincide forrnin g a common conduit in the same manner as the inlet/outlet ports with the same preferences as for the ports. A common outlet/outlet,inlet/outlet, or inlet/inlet conduit may comprise that the common conduit divide into twobranch conduits each of which ends in an inlet or outlet port according to the two functions ofthe common conduit. This kind of branching is typically associated with a valve functionpermitting separate opening of each of the two branch conduits while at the same time leavingthe common conduit open. Theoretically the branching may be the other way round, i.e. with both branches ending at the decomposition chamber (313).

The adsorption unit (201,201,301) may also contain other functionalities as discussed below, e. g. a flow changing function, one or more valves, one or more sensors etc.

The total volume of the adsorbent (113a,213a,313a) should be sufficient for two or moreseparate medical treatments with administration of nitrous oXide lasting for about 15 minuteseach (mean administration times). A typical range is 10-50 separate treatments. This meansthat the amount of adsorbent per adsorption unit should be sufficient for a total effectivecollecting time in the interval of > 30 min with a typical interval of 50 - 750 min. Foradsorbents of essentially the same bulk density (660-740 g/L), particle size (1.5-2.5 mm) andspecific capacity (0.075 g N20/ g adsorbent) as the adsorbent used in the experimental part,this means that suitable volumes may be found in the interval of 5 - 30L per adsorption unitwith a weight in the interval of roughly from 1-2 kg to 20 kg. For adsorbents having otherdensities, particle sizes and capacities per unit volume, suitable intervals for weights andvolumes may be found by adapting these general guidelines to the actual densities, particle sizes and specific capacities of these other adsorbents.

The outer dimensions of the chamber including isolation, walls and the like are typically: a)the height (along the flow direction) is typically > 10 cm such as within the interval of 20 -180 cm, and b) the cross-sectional area (orthogonal to the flow direction) corresponds to acircular cross-sectional area with a diameter > 5 cm, such as within the interval of 10 - 100cm, such as 10 - 80 cm. The shape of the cross-sectional area of the unit as well as of the chamber and the adsorbent is preferably circular.

AdsorbentThe adsorbent (113a,213a,313a) is typically in the form of a porous bed. This bed preferably 9comprises a bed of packed particles, preferably porous particles, e. g. comprising Chemistry and/or micropores in a size range classifying the material as a molecular sieve. Suitablernicopore sizes are found in the interval of 1-12 Ångström for removing nitrous oXide from agas stream containing exhalation air, i.e. a gas stream containing nitrous oXide together Withoxygen and typically also moisture (H20) and/or carbon dioXide. The particles shall havesizes such that the void Volume between the particles When packed to a bed defines a through-passing macroporous system Which permits floW transport of inhalation air and desorbing gasthrough the bed. Suitable particle sizes for particulate materials are found Within the intervalof 0.5 - 10 mm, With preference for Within 1 - 5 mm (diameters). This includes that a minorpart of the particle material may be particles With sizes outside these ranges, e. g. < 25% or <10 % or < 5% or < 1 %. The particles are preferably spheroidal, i.e. rounded including in particular beaded forms such as in the form spheres.

The adsorbent (113a,213a,313a) may alternatively be a macroporous monolith or plug eXhibiting micropores of the sizes given above for particles.

Suitable adsorbent materials are found amongst adsorbent materials od the above-mentionedtype having a capacity for adsorbing nitrous oXide in the interval of 0.025 - 0.25 g of N20/g adsorbent material.

Suitable adsorbent material should be stable under the temperatures applied during adsorption and desorption, i.e. from around 15-20°C to the upper temperatures given for desorption.

The adsorbent (113a,213a,313a) is reversible With respect to adsorption/desorption. ln otherWords it can be re generated after adsorption to give an adsorbent having sufficient adsorbin gcapacity for nitrous oXide and through-floW capacity for being reused in the system of theinvention. The regeneration is carried out by passing a desorbing gas, preferably heated,through the adsorbent to desorb nitrous oXide. The adsorbent material should preferably allowfor regeneration at least 5 or at least 10 or at least 15 or at least 20 times With a retainedcapacity of 2 50 %, such as 2 60 % or 2 75% for removing or binding or adsorbing nitrous oXide from eXhalation air.

An important class of adsorbent material are zeolites Which may be either natural zeolites or more preferably modified zeolites, e. g. With native Na+ ions being replaced With Ca2+ ions.

Suitable materials can be obtained from among others Merck, Darmstadt, Germany (Moleculare sieve 0.5 nm) and Grace Davison, Grace GmbH, Worms, Germany (Molecular sieves MS S 624).

Further guidelines for selecting adsorbent materials to be used in the invention are found inliterature related to adsorption of nitrous oXide from industrial off-gases (e. g. US 6,080,266(UOP LLC), US 6,719,827 (Air Products and Chemicals, Inc), US 20100071552 (Virani et al)etc) and in eXhalation air (e. g. WO 2009095601, WO 2009095605 and WO 2009095611 (allof Air Liquid, US 3941573 (Chapel), US 5928411 (DragerWerk), US 3,941,573 (Chape1)).See also Stockholms lans landsting xvyvwnsllse Report 2007-03-08 “Removal of laughing gasfrom air by the axe zeolites", and Report 2010-06-10: “Removal of laughing gas from air atderitists by using zeolites” (compiled by IVL)) Reversible nitrous oXide adsorbents (113a,213a,313a) for Which there is a measurableparameter Which changes as a function of the proceeding of the adsorption of nitrous oXideWill have a great potential for use in the invention. By selecting this kind of adsorbenttogether With an appropriate sensor (308a,b,c) it Will be possible to measure When theproceeding of the adsorption front has reached one or more predeterrnined position along thefloW direction in the adsorbent during adsorption (position = longitudinal position). Everysuch position Will represent utilized capacity (= a particular degree utilization of the capacity)or of remaining capacity to utilize (= available capacity). The outlet end of the adsorbent Willmean that 100% has been utilized With no remaining capacity to utilize. Other predeterrninedpositions may stand for e.g. 2 50 %, 2 75 %, 2 85 %, 2 90 % of the initial capacity is utilized(or S 50 %, S 25 % S 15 %, S 10 % of the initial capacity remains to be utilized or is stillavailable). A finding that the adsorption front has reached a certain position can be used foralerting personnel handling the system about disconnecting the unit for subsequent desorptionand further processing of desorbed nitrous oXide. Changes in the time needed for theadsorption zone to reach a certain predeterrnined position between repetitive occasions of useof the same adsorbent/unit Will be indicative about the latest status of the Working efficiencyof the adsorbent/unit. It can be envisaged that this might be used for determining When an adsorbent/adsorption unit needs be discarded/repacked With fresh adsorbent material.

The adsorption unit may also have a memory (310b) Which is part of the memory (310a+b) of a logging arrangement (309a+b) of the system of the invention as discussed under D. Logging 11 arrangement below.

Every adsorption unit of the pool typically comprises a carrier function (318) comprising e. g.a) Wheels (318a) and/or one or more handles (318b) fiXedly mounted on the vessel containing the chamber/adsorbent, or b) a cart for carrying the vessel containing the adsorbent.

A. DOCKING ARRANGEMENT FoR ADsoRPT1oN (DAads)Docking arrangement DAadS (202) is associated With the adsorption of nitrous oXide. Thearrangement is adapted for connecting a face mask (204) of an individual eXhaling nitrousoXide to a recipient (205 ) for eXhaled air depleted in nitrous oXide via an adsorption unit(201). A typical docking arrangement DAadS (201) comprises:a) an upstream 1st connection Clads (219a) for connecting the inlet port lPadS (214a) of anadsorption unit (201) to the outlet OLmaSk (212) of a face mask (204), andb) optionally a doWnstream 2nd C2ads (219b) for connecting the outlet port OPadS (214b) ofthe same adsorption unit (201) to the recipient (205) for eXhaled air depleted in nitrousoXide, preferably to ambient atmosphere, or altematively to a Waste storage vessel.EXhaled air depleted in nitrous oXide may be discharged directly from the outlet port to ambient atmosphere. This can render the connection C2ads (219b) obsolete.

The system has one, two or more of docking arrangement DAabS(202) for use at differentlocations of a health care unit. The arrangement DAabS is preferably mobile in the sense that itcan disconnected/reconnected from a face mask and transported between patients and/or locations Where there is a need for administering nitrous oXide..

B. DOCKING ARRANGEMENT FoR DEsoRPT1oN (DAM)Docking arrangement DAdeS (203) is associated With desorption of nitrous oXide. Thearrangement (203) is adapted for connecting a source (206) of desorbing gas to an apparatusfor further processing of nitrous oXide via an adsorption unit (201) Which have been chargedWith nitrous oXide in docking arrangement DAabS (202). A typical docking arrangement DAdeScomprisesa) optionally an upstream 1st connection Cldes (220a) for connecting the inlet port IPdeS(215a) of an adsorption unit (201) to a source (206) for desorbing gas, andb) a doWnstream 2nd connection C2des (220b) for connecting the outlet port OPdeS (215b) ofthe same adsorption unit (201) to the inlet port IPapp (217) of an apparatus (207) for 12further processing of nitrous oXide released by the desorbing gas When it passes through the adsorption unit.The source for desorbing gas has been discussed above together With the inlet portlPdeS.(215a). Air from ambient atmosphere (206) may be used directly as desorbing gas Without any preprocessing. The need for connection Clads (220a) may then be obsolete.

Either one or both of the docking arrangements DAabS (202) and DAdeS (203) may comprise afloW changing function (223a,b), a heating function (222), valve functions, a sensor (208a,b) of the various arrangements and functions described below.

C. MEASURING ARRANGEMENT The system is preferably associated With a measuring arrangement Which comprises one ormore sensors (208a,b,308a,b,c). The arrangement/sensors are capable of measuring amountsof nitrous oXide retained in the individual adsorbents during and/or after adsorption. Thesensors may be based on measuring changes in Weight (208a,b) of an adsorbent/unit, changesin available and/or utilized capacity (308a,b,c) and/or other parameters changing as aconsequence of the adsorption, e. g. the position of the adsorption front (308a,b,c) duringongoing adsorption, changes in level of nitrous oXide in the adsorption floW doWnstream ofthe adsorbent (primarily only of break-through), changes in temperature (308a,b,c) in theadsorbent due to evolution of heat during adsorption (see above) etc. Thus a typical sensorused in the measuring arrangement may be a Weight sensor (208a,b), a spectrometric sensor, a temperature sensor (308a,b,c) etc.

In principle any parameter for Which a measurable change also indicates a measurable changein amount of nitrous oXide on the adsorbent can be used. Sensors measuring consumption ofnitrous oXide, such as number of eXhalations/inhalation (sensor: a pulse meter), loWering ofamount of nitrous oXide in the source (221) of nitrous oXide etc, could also included in themeasuring arrangement. With respect to number of inhalations/exhalations, individuals mostlikely Will have to be grouped, e. g. according to Weight, sex, age, health status, etc each ofWhich group have a relatively narroW interval for volume of inhaled air per inhalation/eXhalation. ln one variant of the measuring arrangement, there is a sensor (208a,b) Which is common for several adsorption units (201) . Sensors (208a,b) in arrangements of this kind may be based 13on weighing (scales) and are preferably part of A) the apparatus for further processing (207), B) docking arrangement DAabS (202), and/or C) docking arrangements DAabS (203). Othersuitable sensors (common to several adsorption units (201)) are: Sensors based onconsumption of nitrous oXide (measured e. g. at the source (221) of nitrous oXide) and number of inhalations/eXhalations (measured at the face mask (204, for instance).

In another variant, there is a sensor associated with individual adsorption units (308a,b,c).This arrangement is preferably based on sensors measuring temperature changes or otherchanges in the adsorbent due to adsorption, and/or changes in the level of nitrous oXide in theadsorption flow downstream the adsorbent but still within the adsorption unit (primarily onlybreak-through).

A potentially interesting variant comprises one, two or more temperature sensors (308a,b,c)placed at different downstream positions in an adsorbent (313a) for which the adsorption ofnitrous oXide is exothermic; see above under The pool of adsorption units, subheadingAdsorbents. This implies a variant of the present inventive which comprises thatA) The adsorbents (313a) in the adsorption units (301) comprise adsorbent material for whichthe adsorption of nitrous oXide is eXothermic and leads to measurable temperature increaseswhere adsorption is ongoing. A heated front moving downstream in the adsorbent duringadsorption will be indicative of the ongoing adsorption and of the position of the adsorptionfront at different times.B) One or more temperature sensitive sensors (308a,b,c) whicha) are capable of measuring changes in temperature in the adsorbent caused by adsorptionof nitrous oXide, andb) are placed at different predetermined longitudinal positions between the inlet end andthe outlet end of the adsorbent (313a).One predeterrnined position can be in the central part and second position close to the outletof the adsorbent (313a), corresponding to about 50 % and about 10 %, respectively, of thetotal capacity still being available. Future results are likely to show that either upward flow or downward flow is to be preferred.

D. LOGGING ARRANGEMENTThe system of the invention typically comprises a logging arrangement (309a+b) for keeping track of changes in functional status of the individual adsorption units (301) and to alerting 14When to discard and replace a particular unit With a freshly prepared unit, i.e. When the unit is too bad for further regeneration. This implies that the system of the invention also may include an alarrn function.

A central part of the logging arrangement is a memory (310a+b) for storinga) a unique identification code for every adsorption unit, andb) data reflecting Working efficiency for at least the latest time of use for the individualadsorption units, optionally including also corresponding data for a freshly preparedadsorbent/unit, and preferablyc) predeterrnined limit values for disqualifying/qualifyin g a unit for repetitive use (valuespreferably data corresponding to data of (b)).Stored data of type (b) refer to values obtained by the measuring arrangement and includealso data Which are derived from such values. In particular adsorption capacity data and/or floW property data (e. g. pressure drop at the Working conditions) are stored.

The memory of the arrangement may comprise a local memory (309b) associated With everyadsorption unit (301) and/or a central memory (309a) separate from the local memories. Alocal memory may be a physically attached to or physically separated from its adsorption unitand/or typically contains the unique identification code for the unit possibly together Withother information collected at least for the latest time of use of the unit, or a reference to suchinformation in a central memory for instance via the identification code. The central memory(310a) typically includes the necessary information for keeping track of important changes inunity-specific data of the kind mentioned in the previous paragraph. Alternatively the centralmemory only contains the identification code and collects all or a part of the unit-specific data from the appropriate local memories by referring to this code.

The local memories and/or the central memory may be in the form of a conventional logg-book or label With the stored information in typed-out form, or as readable and/or Writeableelectronic memories or the like. Transmission of information betWeen the memories may be Wire-less or via Wires.

HEATING ARRANGEMENTThe heating arrangement comprises one or more functions (222,322) each of Which is capable of heating the adsorbent in every adsorption unit to effectuate quick and efficient desorption when a unit is connected for desorption. Heating may take place via direct heating of the adsorbent, e. g. micro-wave heating, or by preheating the desorbing gas upstream of the adsorbent. ln one main variant there is a heating function (322) in individual adsorption units (301). Thisheating function is then preferably placed between the inlet port IPdeS (215a) for thedesorption flow and the adsorbent (313a), preferably in the upstream end of the chamber(313), e.g. in the gap (313c), or in the inlet conduit (217a).

In another main variant the heating function is common to several adsorption units. Theposition for the heating function is then preferably upstream of the connection Cldes (220a) ofdocking arrangement DAdeS (203). ln the case there is a flow changing function FCFdeS downstream of a heating function of thetype described below, there should be a cooling function between the heating function and theflow changing function. This in particular applies if the flow changing function FCFdeS is ablower since conventional blowers are norrnally not designed to resist preheated gas flows.Cooling function should be avoided on the adsorption units (201) and are preferably placed ondocking arrangement DAdeS (203) or in the apparatus for further processing (207).

A heating function (222,322) shall be capable of heating the through-passing desorbing gasand/or the adsorbent (313a) to a temperature enabling efficient release of nitrous oXide fromthe adsorbent. Suitable temperatures depend on the desorbing gas, adsorbent material etc, andare typically found in the interval of §400°C, such as 100-400°C or 100-250°C. The effect ofthe heating function at least for preheating should be within the interval of 150-2500 W withpreference for within 200-500 W. The heater may be gradually adjustable with respect toeffect.

FLOW REGULATING ARRANGEMENTS The system of the invention is associated with a flow regulating arrangement whichcomprises two parts: Adsorption part and Desorption part. The arrangement comprisesvarious flow functions, such as flow changing functions PCF, valves, vents etc. The majorpart of these functions are part of the apparatus (207) for further processing, the face mask arrangement (204), the source (206) for desorbing gas and/or the waste recipient (205) all of 16Which are well known in the field. See the references cited above. The remaining flow functions, if any, are present on the adsorption units (201) and/or the docking arrangementsDAadS (202) and/or DAdeS (203). A general rule is to place as few flow functions as possible on the mobile adsorption units.

Flow changing functions PCF are used for initiating, stopping, increasing and/or decreasingflow velocity. If present in the adsorption part they are called FCFadS and in the desorptionpart they are called FCFdeS. Flow changing functions are preferably blowers and/or preferablyfrequency controlled and/or preferably gradually adjustable with respect to flow Velocity. Thisapplies to in principle every flow changing function which is part of the flow regulating arrangement and is independent of position in the arrangement.

Adsorption part of the flow regulating arrangement A predicted preferred variant of the invention presumes that the flow of eXhalation air(=adsorption flow) leaving a face mask arrangement (204) is sufficient for the flow to passthrough the adsorption unit (201). There would be no need for any extra flow changingfunction FCFadS for the adsorption flow. However, this very much will depend on the variationin the adsorption flow (eXhaled air) both during the treatment of an individual and betweentreatments and/or individuals. It is therefore believed that the system of the invention willbecome more versatile if a flow changing function FCFadS is included in the adsorption part ofthe flow regulating arrangement, e. g. as indicated in the variants illustrated by figures 2 and 3.This means in the face mask arrangement (204), docking arrangements DAadS (202), the mobile adsorption units (201), and/or the arrangement for the waste recipient (205).

In one variant a flow changing function FCFadS (223a) is common to several adsorption units(201). This means that the function is present a) on the face mask arrangement (204), b) onthe docking arrangements DAadS (202) upstream of the connection Clads (219a) and/ordownstream of the connection C2ads (219b) and/or c) on the arrangement for the waste recipient (205). Preferred positions are (b) or (c). ln other variants of the invention, individual adsorption units comprise a flow changingfunction FCFadS (324) which typically is placed in the inlet or outlet conduits (116a,216a,316aand 117b,217b,317b, respectively). 17An advantageous variant with a flow changing function in an inlet conduit is illustrated in figure 3. In this variant a flow changing function FCFadS (324) placed upstream ordownstream of the adsorbent (313a) is combined with an air inlet (325) (e. g. in the form of anair inlet conduit) placed between the inlet port IP ads (314a) and the adsorbent (313a) andupstream of the flow function FCFadS (324). The preferred positions for the air inlet and thefunction FCFadS (324) are in the inlet conduit (316a). This arrangement with its air inlet maybe used for controlling the flow velocity given by a flow function FCFadS (324) to maintain adesired flow Velocity through the adsorbent without risk for disturbing the function of aconnected face mask . The arrangement may be combined with a flow sensor (flow meter orpressure sensor) placed in the inlet conduit (316a) downstream of the air inlet (325) but upstream of the flow function FCFadS (324) to effectuate the control function.

The arrangement described in the preceding paragraph may also be used for the desorptionflow; see figure 3 where the inlet port IPadS (314a) coincides with the inlet port IPdeS (315a)and their inlet conduits coincide with each other meaning that the flow changing function PCF(324) is common for the adsorption flow and the desorption flow. It may then be appropriatethat the air inlet (325) is associated with a valve function perrnitting closing of the air inletduring desorption when the common inlet port (314a,315a) is connected to a source fordesorbing gas via a docking arrangement DAdeS. Altematively the air inlet may be designed tohave a dual function and work as an inlet port IPdeS for desorbing gas such as air from ambientatmosphere during desorption and as an air inlet during adsorption as described above. Inother words the arrangement with an air inlet may comprise a common inlet/inlet conduitwhich in the upstream direction divides into two branches each of which is ending in an inletport. One of these inlet ports has the dual function described previously While the other one ofthese two ports is an inlet port lPadS during adsorption and is preferably closed duringdesorption. The branching is typically associated with a valve function comprising a) a first position for the adsorption mode permitting flow from both inlet ports lPadS and the air inlet (= IPdeS during desorption) to the chamber,b) a second position for the desorption mode permitting flow from the inlet port lPdeS to thechamber while the other port preferably is closed, andc) possibly a third position permitting flow through the inlet port lPadSwhile the other port (air inlet) is closed Desorption part of the flow regulating arrangement 18In one variant a flow changing function FCFdeS (223b) for desorption flow may be common for several adsorption units. This arrangement means that the flow changing function may be p1aced a) upstream of the connection Cldes (220a) of docking arrangement DAdeS (203) fordesorption, i.e. on the docking arrangement or as part of the source for desorbing gas,and/or b) downstream of the connection C2des (220b) of the same docking arrangement, i.e. on thedocking arrangement or as part of the apparatus for further processing 82079.

This is i11ustrated in figure 2b with flow changing function FCFdeSs (223b) p1aced in dockingarrangement DAdeS (203).

In other variants of the invention, individual adsorption units comprise a flow changingfunction FCFadS (324) which is present between the in1et port IPdeS (315a) and the chamber(313a) and/or between the chamber (313a) and out1et port OPdeS (315b). The preference is forin the in1et or out1et conduits (116a,216a,316a and 117b,217b,317b, respective1y).

An advantageous variant with a flow changing function in an in1et conduit for desorption flowis i11ustrated in figure 3 and discussed above under Adsorption part of the flow regulating arrangemen”.

Other functionalities in the system.

The system may a1so contain a poo1 of one or more mutua11y rep1aceab1e adsorption units forremoving an anaesthetic agent present together with nitrous oXide in an anaesthetic gas (notshown). The system then encompasses the appropriate docking arrangement for rep1aceab1einserting/disp1acing these units. This docking arrangement may be p1aced upstream of theconnection Clabs (219a) of the docking arrangement DAabS (202), such as within this dockingarrangement. A1temative1y the chamber with an adsorbent for an anaesthetic agent may becombined with the chamber (313a) for a nitrous oXide adsorbent within the same adsorptionunit (with the adsorbent for the anaesthetic agent preferab1y p1aced upstream of the nitrous oXide adsorbent).

The system may a1so comprise a function for removing partic1es (fi1ter function, not shown)and/or a function for removing moisture (moisture adsorbent, e. g. si1ica materia1, not shown) from the incoming adsorption flow (eXha1ation air) and p1aced upstream of the adsorption unit 19 for nitrous oXide and the adsorption unit for an anaesthetic agent. A filter function and/or a moisture adsorbent are preferably placed downstream of the connection Clabs (219a) of docking arrangement DAabS (202) and/or the connection Clabs (220a) of docking arrangement DAdeS (203), and preferably as a part of a docking arrangement. In the case adsorptions units for an anaesthetic agent are are included in the inventive system, a particle filter function and a moisture adsorbent, if present, should be placed upstream such extra adsorption units..

METHOD ASPECT OF THE INVENTION This aspect is a method using the system described above for the purpose discussed for the system aspect of the invention. The method comprises the steps of: i) ii) iii) iv) V) vi) vii) providing the system as described above, connecting a nitrous oXide adsorption unit (201) of the pool via docking arrangementDAadS (202) to an individual eXhaling nitrous oXide, allowing eXhalation air to pass through the adsorption unit (201) until the saturation ofthe adsorbent (313c) has reached a predetermined value based on a) a starting total capacity value for a freshly prepared adsorbent of this adsorption unit, orb) possible reductions in this value based on the latest prior use of this adsorption unit,transferring the adsorption unit from docking arrangement DAadS (202) to dockingarrangement DAdeS (203) thereby connecting the unit via the connection Cldes (220a) onthe docking arrangement DAdeS (203) to a source for desorbing gas (206) and to theapparatus (207) for further processing via the connection C2des (220b) on the samedocking arrangement (203),allowing desorbing gas, preferably heated, to pass through the adsorbent (313c) to release nitrous oXide and passing the desorbing gas plus nitrous oXide to the apparatus(207) for further processing until the adsorbed nitrous oXide has been completelydesorbed, optionally maintaining the flow of desorbing gas to pass through the adsorbent (313c),now at ambient temperature, (heating function off) and possibly With the adsorption unit(201) disconnected from further processing of nitrous oXide and preferably With anmoisture adsorbent connected upstream of the adsorption unit, releasing the adsorption unit (201) from docking arrangement DAdeS, and a) reconnecting this adsorption unit (201), or b) connecting another adsorption unit (201”) of the pool 5 to docking arrangement DAabS (202) While retuming the previously used adsorption unit (201) to the pool, i.e. presuming that alternative (b) is selected, viii) optionally repeating the sequence of steps (ii)-(vii.a) one or more times With the sameadsorption unit, possibly interrupted With the sequence of steps (ii)-(vii.b), until thecapacity and/or floW properties for an adsorption unit have deteriorated to a leveldisqualifying it for further repetitions Whereupon the unit is discarded and replaced With a freshly prepared adsorption unit Preferences in the method are mentioned in the description of the system aspect of the invention.

A preferred method aspect comprises that a unit is disqualified based on capacity and/or floWproperty data derived from measurements made by the measurin g arrangement of the systemand/or by general guidelines given by the manufacturer. Measurement of capacity and floWproperties has been discussed above. General guidelines of interest may have been set upempirically and typically comprise a) an upper limit for number of regeneration cycles, b) aminimum total time for adsorption (sum for all cycles run With a particular adsorption unit), c)the time needed for reaching a predetermined saturation level, d) a minimum available totalcapacity in absolute amount or in relation to available total capacity before or found after the first time the adsorption unit is used in the inventive systemetc.

Measured values as Well as predeterrnined limit values etc are typically stored in the memory of the logging arrangement of the system.

A third aspect of the invention is an adsorption unit as generally defined in original claim 1 With the characteristic features as given in subclaims and elseWhere in this specification.

EXPERIMENTAL PART EXAMPLE 1 Instrumentation and chemicals Gas mixture: 50% nitrous oXide 50% oXygen from tubes.

Spectrometer: Sick IR for detecting nitrous oXide at the outlet end of the columnColumn/reactor: Tube With a height of 20 cm, upWard floW, Flow 3 L/min, three therrno elements With one at 1 cm distance from the inlet, one at the half-height, and one at the 21Outlet 18 cm from the top.

Adsorbent material: 1275 g Sylobead ®MS S 624 (Grace & Co, Cambridge, MA USA) Temperature: Room temperature. Adsorption temperature 120-200°C. 5 ResultsAdsorption: Break-through at the outlet of the column occurred after 46 min. The totalcapacity of the column Was determined by Weighing to 74 g. During the experiment thetemperature at the inlet (1 cm upstream of the inlet) had increased from 28°C to 41°C after10 min and at the outlet (18 cm upstream of the inlet) from 30°C to 83°C after 30 min. The10 reason for the temperature increase is that adsorption heat is released. It Was also noted thatthe temperature increase Was stopped at 41°C at 1 cm upstream of the inlet. This isinterpreted as saturation With nitrous oXide at this part of the adsorbent. Adsorption heat Wassuccessively released When the adsorption front moved upWards (heat front). Thistemperature increase stopped at the outlet (and also in the Whole adsorbent) When the15 adsorbent Was fully saturated. This is an indication that release of adsorption heatpotentially might be useful for indicating proceeding saturation degrees for this kind ofadsorbents.Desorption: The column after adsorption Was heated to 120-200°C With an air floW of 10mL/min passing through and With IR measurement of nitrous oXide at the outlet. After 30 20 minutes no further nitrous oXide could be detected at the outlet.

These eXperiments Were repeated 5 times With essentially the same results.

While the invention has been described and pointed out With reference to operative 25 embodiments thereof, it Will be understood by those skilled in the art that various changes,modifications, substitutions and omissions can be made Without departing from the spirit ofthe invention. It is intended therefore that the invention embraces those equivalents Within the scope of the claims Which follow. 1. 22CLAIMS A system forI) co11ecting nitrous oXide in air eXha1ed by an individua1 Which via a face maskarrangement (= face mask) (204) having an Outlet OLmaSk (204) for eXha1ation, andII) de1ivering the nitrous oXide co11ected in (I) to an in1et port IPm (217) of an apparatusfor further processing of nitrous oXide,characterized in comprising a pool of one, more mutua11y rep1aceab1e through-floWadsorption units (201), each of Which comprises a nitrous oXide reversib1e adsorbent(213a) p1aced in a through-floW chamber (213) and has:i) an in1et port IPadS (214a) for in1et of eXha1ation air (adsorption floW),ii) an out1et port OPadS (214b) for discharging gas processed in the chamber to a Wasterecipient,iii) an in1et port IPdeS (215a) for in1et of a desorbing gas (desorption floW), andiv) an out1et port OPdeS (215b) for discharging desorbing gas from the adsorbent,together WithA) a docking arrangement DAadS (202) Which is associated With adsorption of nitrousoXide and comprises:a) a connection Clads (219a) for connecting the out1et port OLmaSk (212) to the in1etport IPadS (214a), andb) optiona11y a connection C2ads (219b) for connecting a Waste recipient (205 to theout1et port OPadS (214b), andB) a docking arrangement DAdeS (202) Which is associated With desorption of nitrousoXide and comprises:a) a connection Cldes (220a) for connecting a source for desorbing gas to the in1et portIPdeS (215a) andb) a connection C2des (220b) for connecting the out1et port OPdeS (215b) to the in1etport lPapp (217).

The system of c1aim 1, characterized in that the system comprises a carrier function (318) to support the mobi1ity of the individua1 adsorption units (301).

The system of any of c1aims 1-2, characterized in that the floW direction for desorbing floW through the adsorption unit is opposite to, or has the same direction as the floW

Claims (11)

1. A system forI) co11ecting nitrous oXide in air eXha1ed by an individua1 Which via a face maskarrangement (= face mask) (204) having an Outlet OLmaSk (204) for eXha1ation, andII) de1ivering the nitrous oXide co11ected in (I) to an in1et port IPm (217) of an apparatusfor further processing of nitrous oXide,characterized in comprising a pool of one, more mutua11y rep1aceab1e through-floWadsorption units (201), each of Which comprises a nitrous oXide reversib1e adsorbent(213a) p1aced in a through-floW chamber (213) and has:i) an in1et port IPadS (214a) for in1et of eXha1ation air (adsorption floW),ii) an out1et port OPadS (214b) for discharging gas processed in the chamber to a Wasterecipient,iii) an in1et port IPdeS (215a) for in1et of a desorbing gas (desorption floW), andiv) an out1et port OPdeS (215b) for discharging desorbing gas from the adsorbent,together WithA) a docking arrangement DAadS (202) Which is associated With adsorption of nitrousoXide and comprises:a) a connection Clads (219a) for connecting the out1et port OLmaSk (212) to the in1etport IPadS (214a), andb) optiona11y a connection C2ads (219b) for connecting a Waste recipient (205 to theout1et port OPadS (214b), andB) a docking arrangement DAdeS (202) Which is associated With desorption of nitrousoXide and comprises:a) a connection Cldes (220a) for connecting a source for desorbing gas to the in1et portIPdeS (215a) andb) a connection C2des (220b) for connecting the out1et port OPdeS (215b) to the in1etport lPapp (217). The system of c1aim 1, characterized in that the system comprises a carrier function (318) to support the mobi1ity of the individua1 adsorption units (301). The system of any of c1aims 1-2, characterized in that the floW direction for desorbing floW through the adsorption unit is opposite to, or has the same direction as the floW 5 23direction of absorption floW (eXha1ation air), With preference for IPadS (314a) coinciding With OPdeS (315b) and/or OPadS (314b) coinciding With IPdeS (314b) The system of any of c1aims 1-3, characterized in comprising a heating arrangementcomprising one or more functions (222,322) for heating the adsorbent of the individualadsorption units, With preference for a) one of said heating functions (222) being present on said docking arrangement DA de,(203) and p1aced upstream of the connection Cldes (220a) and/or b) one of said heating functions (322) being present on every adsorption unit (301) andp1aced between the in1et port OPdeS (315b) and the adsorbent (313a). The system of any of c1aims 1-5 , characterized in being associated With a floWchanging function FCFadS (223a,322) ) for changing adsorption floW through theadsorption unit (201,301), and/or a floW changing function FCFdeS (223,324) for changingthe desorption floW through the adsorption unit (201,301), The system of c1aims 6, characterized ina) said floW changing function FCFdeS being associated With the apparatus for furtherprocessing (207) and/or With the source (206) of desorbing gas, and/orb) said floW changing function FCFadS (324) being associated With the face mask (204)and/or the in1et end (316a,317a) of an adsorption unit. The system of any of c1aims 1-7, characterized in being associated With a measuringarrangement Which comprises one or more sensors (208a,b,308a,b,c) Which are based onmeasuring during and/or after adsorption the amount of nitrous oXide on the adsorbent (213a,313a). The system of c1aims 8, characterized in that A) the adsorbents (313a) in the adsorption units have been se1ected amongst adsorbentsfor Which the adsorption of nitrous oXide is eXothermic deve1oping measurab1echanges in temperature Where adsorption is ongoing indicating the advancing front ofadsorption, and B) one or more temperature sensitive sensors (308a,b,c) Which 24a) are capable of measuring changes in temperature in the adsorbent (3l3a) caused by adsorption of nitrous oXide, andb) are placed at different predetermined longitudinal positions between the inlet end (3l3c) and the outlet end (3l3b) of the adsorbent.. 59. The system according to any of claims 1-9, characterized in comprising a loggingarrangement (3l0a+b) in Whicha) capacity data and/or floW capacity data and/or sum of running times for adsorption forat least the latest time of use for the individual adsorbents of the pool etc, and possiblyl0 also corresponding initial values for freshly prepared adsorbents of the pool, and/or b) preset limit values for disqualification/qualification of the individual adsorption units for repetitive use in the system.