Method of distributing a liquid in a fluid bed reactor and fluid bed reactor

Abstract: A method of distributing a liquid in the fluid bed of a down-flow, or an up-flow, fluid bed reactor (50) comprising a vertical reactor (54) with an inlet, an outlet, and a fluid bed (A,B,C) of particles, wherein (a) the particles (51) and liquid proximal to the liquid inlet are agitated to divide the fluid bed into (i) a turbulent zone (A) having vigorously moving particles, and (ii) a non-turbulent zone (B); said non-turbulent zone adjoining said turbulent zone; and (b) that the extent of said turbulent zone is determined by a degree of agitation selected within a range from (i) a degree of agitation providing turbulence only in the uppermost/lowermost part of the fluid bed, (ii) to a degree of agitation providing turbulence of the particles throughout the fluid bed; a down-flow, or an up-flow, fluid bed reactor for use in carrying out the method; and fluid bed particles for use in carrying out the method.

Description: 1. BACKGROUND OF THE INVENTION The Technical Field The invention relates to a method of distributing a liquid in the fluid bed of a down-flow, or an up-flow, fluid bed reactor; and a down-flow, and an up-flow fluid bed reactor, and fluid bed particles for use in carrying out the method. Generally, a fluid bed reactor may comprise a vertical reactor with an inlet, an outlet, a fluid bed of particles, and a liquid. The liquid is introduced at the inlet and dispersed, optionally through a gas head in case of down-flow reactors, on the bed of particles which are suspended and fluidized by the liquid. The liquid is conducted through the bed and a pool of reacted and/or unreacted fluid is let out at the outlet. Down-flow fluid bed reactors have liquid inlet at the top of the reactor and fluid bed particles of specific gravity less than that of the liquid. Up-flow fluid reactors have liquid inlet at the bottom of the reactor and fluid bed particles of specific gravity larger than that of the liquid. The suspended particles may be reactive or may carry immobilized reactive components selected for solid phase chemical or physical processes with one or more components of the fluid in procedures such as enzymatic reactions; fermentation; ion-exchange and affinity chromatography; filtration; adsorption; catalysis; immunosorption; solid-phase peptide and protein synthesis; and microbiological growth of microorganisms. Fluid bed particles having at least one active substance are used in a wide variety of applications in chemical and biological processes, such as production and manufacturing of chemical or pharmaceutical products, e.g. for carrying catalysts in liquid phase oil conversion technology, for carrying enzymes for modifying synthetical products, e.g. enzymes such as proteases, invertases, amidases and ring forming enzymes for synthesis of lactones, and carboxypeptidase for synthesis of peptides using solid-phase techniques; fermentation and cell growth, e.g. for carrying cells or substrate; waste water purification, e.g. for carrying enzymes and/or microorganisms, catalysts or adsorbents; chromatographic processes, e.g. high performance liquid chromatography, gel filtration, ion exchange and affinity chromatography, e.g. for carrying adsorbents; diagnostic processes, e.g. for carrying adsorbents for blood purification, dye chromatographic processes for albumine purification; and prophylactic processes, e.g. for carrying immobilized antibodies or antigens in extra-corporal circulations for removal of antigens or antibodies, bacterial toxins or other toxins, and autoimmune diseases. Generally, for a large number of applications, the active substance to be used in a liquid may only temporarily be available or accessible at the right places in the liquid. Thus, for fluid bed particles carrying active substances and often showing large variations in dispersion properties, e.g. sedimention or floatation, the active substances may be carried in an uncontrolled manner e.g. down- or upwards in relation to the liquid depending on the relative density of the fluid bed particles. In fluid bed reactors partially solving the problems of packed bed columns, i.e. the problems of suspended matter clogging up the solid-phase bed which increases the back pressures and compresses the bed, disturbing the flow through the bed, the fluid bed particles are carrying the active substance in a free, fluid phase by applying a flow having an opposite direction to the direction of the relative movement of the fluid bed particles. Thus, fluid bed particles having a density larger than the liquid and moving downwards due to gravity may be kept in a free, fluid phase by an upwards flow of liquid. Also, fluid bed particles having a density less than the liquid and thus moving upwards may due to buoyancy be kept in a free, fluid phase by a downwards flow of liquid. For fluid bed solid-phase chemical processes, the density of the solid-phase fluid bed particles is very important in controlling bed properties. However, up to now, the design of solid-phase fluid bed particles has been limited by the available material. Generally, fluid bed particles may either be designed to be impermeable to the fluid, in which case the available surface area per unit volume is small; or fluid bed particles may be designed to be permeable to the fluid, in which case the material chosen has to have the correct density per se . Unfortunately, the most interesting materials for many applications, e.g. materials such as natural and synthetic polysaccharides like agar, alginates, carrageenans, agarose, dextran, modified starches, and celluloses; synthetic organic polymers and copolymers, typically based on acrylic monomers used for chromatographic purification of proteins in packed bed columns, are not of suitable density per se . Therefore, these materials are difficult to apply in fluid bed reactors. However, certain types of organic polymers and certain types of silica based materials may be produced to provide fluid bed particles of suitable density, but such fluid bed particles may not at the same time be suitable active substances, e.g. for protein purification procedures, where such materials may provide low permeability, non-specific interactions and denature bound proteins. Further, for such polymers, it may be difficult and expensive to design derivatisation schemes for affinity chromatography media. Also, certain types of permeable silica particles have been used for fluid bed applications. However, the properties of these materials are far from optimal. Thus, the materials are instable at pH above 7, fragile to shear forces, and provide non-specific interactions. Generally, in order to carry out solid phase chemical or physical processes in a fluid bed reactor, an even and smooth distribution of fluid in the fluid bed is desired. However, fluid bed reactors known in the art do not have means known per se to avoid formation of channels as well as unwanted turbulence in the particle bed. Prior Art Disclosure US 4 032 407 discloses a tapered bed bioreactor applying immobilized biological catalysts or enzymatic systems on fluidizable particulate support materials consisting of coal, alumina, sand, and glass, i.e. materials heavier than the fluid, particularly an aqueous fluid. EP-A-0 175 568 discloses a three phase fluidized bed bioreactor process comprising purifying effluents in a three phase fluidized bed comprising solid particles being made by mixing a binder with an inorganic material based on aluminum silicate, granulating the resulting mixture, and firing the granules to sinter them. The specific gravity of the sintered granules is adjusted to fall into a specific range from 1.2 to 2.0 by varying the mixing ratio of inorganic powdery materials based on aluminum and binders, said sintered granules having a diameter from 0.1 to 5 mm. EP-A-0 025 309 discloses a downflow fluid bed bioreactor applying biota attached to carrier particles consisting of cork, wood, plastic particles, hollow glass beads or other light weight material and having a specific gravity which is less than that of a liquid sprayed onto the upper part of a fluid bed of suspended carrier particles and conducted downward through the bed. These three disclosures describe particulate support materials to which the attachment of the active substance is restricted to the surface of the particles limiting the amount of active substance to be obtained per unit volume compared to fluid bed particles allowing the active substance to be attached within the particle. Thus, in many applications, it is important to have specifically designed fluid bed particles able to carry as large an amount of active substance per unit volume as possible which fluid bed particles are not available in the prior art. Further, a disadvantage of distributing an introduced liquid in a fluid bed reactor by spraying is the formation of channels in the bed by fluid rays. EP-A-0 005 650 discloses an up-flow fluid bed reactor having fiuidizing fluid flow distributors at the bottom thereof providing flow paths to avoid turbulence effects. Besides requiring complicated flow paths, a disadvantage of such a distributor is that it may be clogged by particulate matter. EP-A2-0 088 404 discloses a fluid bed reactor system for catalytic polymerisation of olefin monomers composed of a cylindrical reaction vessel equipped with distribution plate and agitator disposed in the fluidized bed above the plate and adapted to cause a rotational flow in the fluidized bed, said distribution plate having many passage holes each covered with a cap having an opening the direction of which varies with the distance from the center of the plate and faces the same direction as the direction of the rotational flow. The fluid bed reactor system is intended to reduce various troubles such as blocking of the distribution plate, formation of polymer agglomerates, and stagnation, adhesion, and agglomeration of polymer at the caps. EP-A1-0 007 783 discloses a control system for preventing accumulation of excessive cellular material in a fluidised bed reactor comprising a separator column having means to effect shearing of excess cellular material from the particles to produce in the column a mixture of sheared material and partially stripped carrier particles, said carrier particles being returned to the bed while the sheared material is discharged from the column through the draw-off port. In a specific embodiment the shearing is effected by an agitator arrangement comprising a motor-driven mixing blade operating within the lower portion of the separator column; the rotary speed of the mixing blade being adjusted to an optimum degree of shear for the cellular growth. Excessive pulverisation of the sheared material is avoided by using not a too high rotary speed. Patent Abstract of Japan, Vol. 8, No. 162, C235 (Abstract of JP 59-62 339) discloses a vertically movable agitator for gas fluidization equipment to obtain an effective treatment of powder and granules. Nothing is mentioned nor suggested about distributing a liquid by agitation of fluid bed particles. EP-A2-0 243 845 discloses a fluid bed having a built-in device in form of a perforated plate and/or net for performing gas-solid phase reactions whereby generated voids are destroyed so that a homogeneous fluid bed without large voids is provided. 2. DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method of distributing a liquid in a fluid bed reactor such that the liquid is distributed evenly and with minimal or no turbulence in the fluid bed. (a) Method of Distributing a Liquid in a Fluid Bed Reactor In a first aspect according to the invention this is obtained by providing a method of distributing a liquid in a down-flow fluid bed reactor as claimed in claim 1. In a second aspect according to the invention this is obtained by providing a similar method for an up-flow fluid bed reactor as claimed in claim 4. In this second aspect of the invention the extent of the turbulent zone is determined based on the sedimentation of the fluid bed particles instead of the buoyancy of the particles as in case of the down-flow fluid bed reactor of the first aspect of the invention. Preferred embodiments are claimed in claims 2, 3 and 5, 6, respectively. It is known that fluids and solids can be mixed by agitation. However, to the applicant's knowledge, it is new to apply agitation to fluid bed reactors for the purpose of distributing the liquid flow in the fluid bed, particularly for a down-flow reactor. Apparently, in the art, it has been anticipated that agitation of a fluid bed generates turbulence which may result in unwanted mixing of products and reactants, and in unwanted wear of the bed particles. However, according to the invention, these disadvantages can be limited considerably by agitating a part of the fluid bed, particularly the part of the bed proximal to the inlet of the liquid. Particularly, for a down-flow fluidized fluid bed reactor it has turned out that agitation of the upper part of the fluid bed divides the bed in two zones: i) a turbulent zone with turbulence and vigorously moving particles, and ii) a non-turbulent zone with no turbulence and particles in a stationary fluidized state. The two zones adjoin with a sharp interface across which fluid flow is evenly distributed. The position of the sharp interface is controlled by the degree of agitation which is selected for a given flow of fluid, viscosity, and buoyance/sedimentation of the particles. Thus, according to the invention, a turbulent zone provides an even distribution of fluid flow to the non-turbulent zone with minimal or no turbulence. A number of advantages are obtained. For chromatographic applications, the dispersion of eluant is reduced, i.e. the width of the eluation band is reduced. Also, for enzymatic and fermentation type reactions, enzyme inhibition is reduced as the intermixing of products and substrates is reduced. Further, formation of channels in the fluid bed is minimized. According to the invention, agitation can be effected by stirring the fluid bed or by any agitation means, including mechanical agitation or gas injection. According to the invention, the fluid bed particles can be different or of the same type for both the turbulent zone and the non-turbulent zone. In a preferred embodiment, the turbulent zone may comprise inert particles of slightly different specific gravity than the particles of the non-turbulent zone. In this case, the inert particles positioned in the turbulent zone solely participate in the distribution of fluid, and not in the solid phase processes. (b) Down-Flow, and Up-Flow, Fluid Bed Reactors for Use in Carrying out the Method The invention also provides a down-flow fluid bed reactor for use in carrying out the method, as claimed in claim 7. Also, the invention provides a similar up-flow fluid bed reactor for use in carrying out the method, as claimed in claim 8. In this aspect of the invention the extent of the turbulent zone is determined based on the sedimentation of the fluid bed particles instead of the buoyancy of the particles as in case of the down-flow fluid bed reactor. Generally, compared to packed bed techniques, fluid bed techniques, e.g. to be used in fluid bed chromatography, are better suitable to large scale primary purification of proteins as the steps of centrifugation and filtration can be avoided. Thus, the fluid bed techniques can be used immediately following the production of the protein, e.g. directly applying the produced extract or fermentation fluid to fluid bed purification and conversion. (c) Fluid Bed Particles for Use in Carrying out the Method The present invention also provides particularly preferred fluid bed particles for use in carrying out the methods as claimed in claim 9. Particularly, such fluid bed particles avoid the disadvantages of known carrier materials, e.g. the problems of uncontrolled sedimentation or floatation of active substance and/or its carrier, the poor selectivity and capacity of carriers having immobilised active substances, and the missing possibilities of simultaneously designing and controlling the properties of the active substance and carrier. Preferred embodiments are claimed in claims 10-25. Preferred fluid bed particles comprising density controlling particles having low and/or high densities, and further comprising at least one active substance and at least one conglomerating agent for conglomerating said density controlling particles and substance, the conglomerating agent itself optionally being an active substance, and all constituents in suitable predetermined amounts, provide fluid bed particles of controlled density, particularly fluid bed particles of controlled density with respect to the liquid to be used. Thus, by choosing the amounts appropriately, the relative density of the conglomerate with respect to the liquid to be used can be controlled within the limits suitable for the application. Particularly, fluid bed particles not controlling the active substance as such may be prepared separately in order to provide a material of controlled relative density which can be treated to comprise the active substance. Fluid bed particles may further comprise other substances such as additives, fillings, softeners, etc., and may be designed to e.g. controlled release (also known as sustained release, slow release or "retard" release) of a desired substance from a conglomerate depending on the choice of conglomerating agent, and possibly comprising a suitable surface coating, e.g. of a material such as the ones mentioned for the conglomerating agent, having diffusion or permeability characteristics appropriate to the gradual release of the substance in question from the conglomerate. In its broadest aspect the density may be controlled by selecting density controlling particles from a group of particles consisting of particles of very low density, particularly hollow and impermeable particles having shells of suitable material and properties, however, non-hollow particles may be chosen when appropriate; and particles of very high density, e.g. particles based on suitable heavy elements or compounds. Generally, the fluid bed particles comprise conglomerates of controlled relative density, selectivity, and capacity in terms of controllable interior surface areas and materials e.g. materials having specific chemical and/or mechanical properties. Thus, compared with known carrier particles for fluid and packed bed reactors, fluid bed particles can surprisingly be designed to have a number of advantages not previously obtained. The fluid bed particles can be designed to have a controlled relative density independent of the active substances and the conglomerating agents; heavy particles can be made light, and vice versa, within a wide range of particle sizes; the density can be controlled within very broad limits, e.g. the density of a known material can be controlled for a specific application; the volume percentage of the conglomerating agent can be controlled according to the application; the total size of the final carrier particle can be controlled contrary to known particles having uncontrollable sizes for specific densities suitable for particular rising and falling velocities; further, the fluid bed particles have a relative larger capacity, i.e. a larger accessible volume, compared to e.g. known impermeable carrier particles; also, in preparing such known impermeable carrier particles, the active substances to be applied are limited, e.g. limited to substances that can be attached to the particle surface. However, fluid bed particles, both the impermeable carrier particles and the active substances may be included, e.g. in form of entrapped particles or substances. Also, contrary to known particles having a given mechanical strength and density, the elasticity and the mechanical strength of such fluid bed particles can be controlled independently of the density. Further, pore sizes and e.g. biocompatibility can be controlled independently of the density in order to allow access to the interior of the fluid bed particles and to avoid denaturation e.g. of proteins. "Fluid bed Particle Preparation" Preparation of fluid bed particles may be obtained by various methods known per se , e.g. block polymerisation of monomers; suspension polymerisation of monomers; block or suspension gelation of gel forming materials, e.g. by heating and cooling (e.g. of agarose) or by addition of gelation "catalysts" (e.g. adding a suitable metalion to alginates or carrageenans); block or suspension cross-linking of suitable soluble materials (e.g. cross-linking of dextrans, celluloses, starches or gelatines, or other organic polymers with e.g. epichlorohydrine or divinyl sulfon); formation of silica polymers by acidification of silica solutions (e.g. block or suspension solutions); mixed procedures e.g. polymerisation and gelation; spraying procedures; and fluid bed coating of density controlling particles. Thus, for particularly preferred fluid bed particles may be obtained by cooling emulsions of density controlling particles suspended in conglomerating agents in heated oil solvents; or by suspending density controlling particles and active substance in a suitable momoner or copolymer solution followed by polymerisation. "Preparation by Gelation/Polymerisation in the Emulsified State" A method of preparing fluid bed particles comprises a) mixing density controlling particles consisting of at least one low density particle, preferably hollow, and/or at least one high density particle, said particles being preferably impermeable to the fluid, at least one conglomerating agent made of a material consisting of natural and synthetic organic monomers and/or polymers selected from the group consisting of: i) natural and synthetic polysaccharides and other carbohydrate based polymers, including but not limited to agar, alginate, carrageenan, guar gum, gum arabic, gum ghatti, gum tragacanth, karaya gum, locust bean gum, xanthan gum, agaroses, celluloses, pectins, mucins, dextrans, starches, heparins, gelatins, chitosans, hydroxy starches, hydroxypropyl starches, carboxymethyl starches, hydroxyethyl celluloses, hydroxypropyl celluloses, and carboxymethyl celluloses; ii) synthetic organic polymers and monomers resulting in polymers, including acrylic polymers, polyamides, polyimides, polyesters, polyethers, polymeric vinyl compounds, polyalkenes, and substituted derivatives thereof, as well as copolymers comprising more than one such organic polymer functionality, and substituted derivatives thereof and iii) mixtures of these; said active substance, if present, in predetermined amounts optionally heated; b) emulsifying said mixture in a suitable solvent; c) conglomerating by a suitable means such as gelation by heating/cooling, polymerisation of monomer or monomer mixtures, non-covalent or covalent cross-bonding; and d) isolation and washing of the conglomerate. "Preparation by Gelation/Polymerisation in the Block State" Another method of preparing fluid bed particles comprises a) mixing density controlling particles consisting of at least one low density particle, preferably hollow, and/or at least one high density particle, said particles being preferably impermeable to the fluid, at least one conglomerating agent made of a material consisting of natural and synthetic organic monomers and/or polymers selected from the group consisting of: i) natural and synthetic polysaccharides and other carbohydrate based polymers, including agar, alginate, carrageenan, guar gum, gum arabic, gum ghatti, gum tragacanth, karaya gum, locust bean gum, xanthan gum, agaroses, celluloses, pectins, mucins, dextrans, starches, heparins, gelatins, chitosans, hydroxy starches, hydroxypropyl starches, carboxymethyl starches, hydroxyethyl celluloses, hydroxypropyl celluloses, and carboxymethyl celluloses; ii) synthetic organic polymers and monomers resulting in polymers, including acrylic polymers, polyamides, polyimides, polyesters, polyethers, polymeric vinyl compounds, polyalkenes, and substituted derivatives thereof as well as copolymers comprising more than one such organic polymer functionality, and substituted derivatives thereof and iii) mixtures of these; said active substance, if present, in predetermined amounts in a solvent; and b) conglomerating by a suitable means such as gelation by heating/cooling, polymerisation of monomer or monomer mixtures, non-covalent or covalent cross-bonding; and c) disintegrating the block of conglomerate; and d) segregating the particles, and washing the segregated conglomerate. Thus, e.g. for polysaccharides such as agarose and agar, i.e. materials melting at high temperatures and solidifying at low temperatures, the conglomerating means is by heating/cooling. Further, for acryl derivatives and other monomers or mixtures of these, the conglomerating means can be selected from a group consisting of: a) addition of polymerisation catalyst; b) heating; c) illumination with light; and d) irradiation with ionizing radiation. Particularly for heavily charged polysaccharides and polymers such as alginates and carrageenans, the conglomerating means is non-covalent cross-bonding by addition of a suitable metal ion. However, for polysaccharides in general, e.g. cellulose and its derivatives, and polymers containing e.g. amino, hydroxyl, thiol, and carboxy groups, the conglomerating means is covalently cross-bonding by addition of a suitable cross-bonding agent, e.g. epichlorohydrine, divinyl sulfon, bisepoxyranes, dibromopropanol, glutaric dialdehyde, diamines, and other bifunctional agents. Also, the above-mentioned conglomerating means may be combined in specific cases such as the preparation of conglomerates of agarose-acryl-derivatives and cross-bonded mixtures of agarose and dextran. Further, in the above-mentioned block polymerisation, the segregation step of the polymer block may be obtained by methods known per se , e.g. by granulation and sieving. The fluid bed particles may be used as a solid phase matrix, carrier, or substrate material in a procedure selected from the group consisting of: chromatographic procedures applying non-packed columns including liquid chromatography, ion-exchange chromatography, and biospecific affinity chromatography such as immunosorption and protein A chromatography, and group specific affinity chromatography such as hydrophobic, thiophilic, dye, lectin, and metal chelate chromatography; filtration of a fluid medium; adsorption of at least one selected substance present in a fluid medium; heterogeneous catalysis of a reaction taking place in a fluid medium; immunochemical procedures, including immunosorption; solid-phase synthesis, including solid-phase peptide and protein synthesis, and solid-phase oligonucleotide synthesis; microbiological procedures; enzyme reactor procedures; carriage, on the outer or the interior surface of the particles, optionally after a suitable surface treatment of live cells selected from cells of human, animal, plant, fungal and microorganism origin. Examples of enzyme reactor procedures are: (i) "confinement immobilization" procedures making use of an enzyme (e.g. in the form of an enzyme solution) which is contained within the through-going pores and/or internal cavities of permeable fluid bed particles, and which is prevented, as described earlier, above, from escaping from the fluid bed particles by the presence of a suitable surface coating having diffusion or permeability characteristics such that the desired enzyme substrate(s) and resulting reaction product(s) may migrate through the coating; (ii) "solid-phase covalent immobilization" procedures making use of an enzyme which is covalently bound, via appropriate functionalities, within the fluid bed particles, the resulting fluid bed particles optionally being subjected to a surface treatment to provide a coating of the type mentioned in (i) above. Such procedures might be employed, for example, in the production of high-fructose syrups from sucrose molasses, using a permeable conglomerate containing a suitable "confinement immobilized" or "solid-phase covalently immobilized" sucrase. Definitions of Expressions In the present context the expression "conglomerate" is intended to designate a composite of density controlling particles, which may comprise particles of different types and sizes, held together by conglomerating agents. Conglomerates may be of various sizes and shapes and should preferably exhibit various degrees of mechanical rigidity depending on the application. Further, conglomerates may be chemically active or may be chemically inactive under the conditions applied. The expression "conglomerate of controlled relative density" is intended to designate a conglomerate or a conglomerate particle for which in particular the density controlling particles are chosen in predetermined amounts to provide a certain relative density of the conglomerate with respect to the liquid in which an active substance or another constituent of the conglomerate is to be used so that the floatability or sedimentation, respectively, is controlled. Thus, fluid bed particles are intentionally designed with respect to the density of the medium for their particular purpose of application, including proper consideration of the influence of their sizes on their floating or sedimentation properties. In other media, e.g. during preparation or during storage under e.g. dry conditions, the fluid bed particles may have a density different from than that in the liquid medium of use, such media may be liquids or gases. In the present context the expression "active substance" should be taken in a very broad sense comprising agents having desired properties for their particular purpose of application, e.g. adsorbents, ligands, reagents, enzymes, catalysts; natural substances and substrates, cell aggregates; or nutritional matter for animals living in water; entrapped in or chemically, e.g. covalently, ionically, photochemically, etc. bound to the conglomerate of controlled density. Within the present context the expression "relative density of fluid bed particles" designates the density of the individual fluid bed particles in the wet state, i.e. a state where the conglomerating agent is fully hydrated, but without any interstitial liquid between individual fluid bed particles. This means that the liquid in which the fluid bed particles are used are determinant for the density of the fluid bed particles in as much as this liquid penetrates into the volume of the conglomerating agent, solvates this and fills out the pores. Further, the expression "relative density of the particles" designates the density of the particles relative to the density of the liquid in which the particles are to be used. This relative density is determinant for the tendency of the particles to float or to sediment in a given liquid. The relative density of fluid bed particles is thus dependent on the solvated density of the conglomerating agent, the concentration of conglomerating agent, the density of the density controlling particles (preferably impermeable to the liquid and substantially non-solvated) used to regulate the density and the concentration of these. 3. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is further illustrated by reference to the examples given below and to Figures 1, 4, 5 and 6, wherein Fig. 1A shows a 40X amplified photograph of fluid bed particles of agarose and glass spheres prepared according to Example 1(a); Fig. 1B shows a 40X amplified photograph of selected spherical fluid bed particles of agarose and glass spheres prepared according to Example 1(a); Fig. 1C shows a 40X amplified photograph of fluid bed particles of acrylic acid copolymer and single solid glass spheres prepared according to Example 11; Figs. 4A and 4B show perspective sketches of another preferred embodiment of a down-flow fluid bed reactor; Fig. 5 illustrates the fluid bed particles in a down-flow fluid bed reactor; and Figs. 6A-6D illustrate cross-sections along the lines VIB, VIC, VID, VIE in Fig. 5. 4. DETAILED DESCRIPTION (a) Controlled Liquid Distribution in Fluid Beds and Fluid Bed Reactors Figs. 4A and 4B show perspective sketches of a preferred embodiment of a down-flow fluid bed reactor 40. A dc-motor 41 controlled by a variable speed control 42 provides revolutions of a stirrer 43, which in a turbulent zone A agitates the fluid bed particles to generate a turbulent flow of the liquid flowing down-ward. A sharp interface (generally of few particle diameters) is reached at the non-turbulent zone B in which the particles are stationary and an even and smooth distribution of the liquid is obtained. In order to adapt the conditions of agitation the length of the fluid bed column can be changed by means of interchangeable chromatographic tubes 45. "Down-Flow Fluid Bed Reactor" Fig. 5 shows a longitudinal section of a segment of a down-flow fluid bed reactor 50 comprising a vertical cylinder 54 and a fluid bed A,B,C of particles 51,52,53 suspended in a down-flow fluidizing fluid 56 let in through an inlet at the top of the reactor vessel, the particles 51,52,53 having a specific gravity less than that of the fluid. A gas head 57 is above the surface along the line VIA-VIA. The upper part of the fluid bed is agitated by a plate formed mechanical stirrer 55 dividing the bed into a turbulent zone A, a non-turbulent zone B, and an exit zone C. In the turbulent zone A, the agitated fluid bed particles 51 move vigorously which generates a turbulent flow of the fluid. The turbulence decreases down the turbulent zone A. A sharp interface VIC-VIC is reached at the non-turbulent zone B in which the particles 52 are in a stationary fluidized state. Across the interface VIC-VIC, the fluid flow is distributed evenly, and a smooth fluid flow is obtained in the non-turbulent zone B. In the exit zone C, the pooled reacted and/or unreacted fluid 57 leaves the fluid bed at an interface VID-VID, where particles 53 can become separated from the fluid bed by the fluid flow. Figs. 6A-6C show cross sections of the turbulent zone A along the lines VIB-VIB, VIC-VIC, and VID-VID, respectively, of Fig. 5. Thus, Fig. 6A shows a cross section of essentially randomly moving particles 51, and Figs. 6B & 6C show cross sections of essentially stationary fluidized particles 52 and 53. Fig. 6D shows a cross section, along the line VIE-VIE, essentially without particles. (b) Fluid Bed Particles The density of the solvated phase, i.e. the volume occupied by the conglomerating agent and the active substance will usually be dependent on the specific application of the particles and thus not allowable to be regulated by variation of the concentration of conglomerating agent. Therefore, the density of the fluid bed particles is regulated by the addition of density controlling particles having a density free of choice with respect to the functionality of the fluid bed particles and also having a final concentration in the fluid bed particles free of choice with respect to the functionality, i.e. the functionality of the active principle within the volume of the conglomerating agent is not disturbed by the density and concentration of the density controlling particles. A crude estimate of the final density as a function of the concentration of density controlling particles can be found by the following equation: Density of fluid bed particles= ((d c x v c ) + (d b x v b ))/(v c + v b ) d c = density of solvated conglomerating phase d b = density of density controlling particles v c = volume occupied by solvated conglomerating phase v b = volume occupied by density controlling particles. Differences in the degree of solvation occurring in different solvents have to be corrected for. Thus, for certain conglomerating agents, e.g. heavily charged polymers for ionexchange chromatography, the degree of solvation, i.e. the volume of liquid taken up per gram dry weight, may differ by several hundred percent in fluids with different ionic strength or pH. By way of example the density of fluid bed particles comprising agarose as the conglomerating agent and hollow glass spheres as density controlling particles is regulated by the addition of hollow glass spheres to the liquified agarose, the amount added (for example measured as gram hollow glass spheres per ml agarose) being determinant for the density of the final fluid bed particles. Assuming a density of the agarose phase to be 1.0 g/ml and the volume used to be one liter (1000 ml) and the density of the hollow glass spheres to be 0.2 g/ml and the amount used to be 100 g (corresponding to 500 ml) the calculated density would be: ((1.0 x 1000) + (0.2 x 500))/(1000 + 500) = 0.73 g/ml If only 50 g of hollow glass beads were added the calculated density would be: ((1.0 x 1000) + (0.2 x 250))/(1000 + 250) = 0.84 g/ml If instead of the hollow glass spheres, the density controlling particles used were solid glass spheres with a density of 2.5 g/ml and 500 g were used to the same amount of agarose, the calculated density would be: ((1.0 x 1000) + (2.5 x 200))/(1000 + 200) = 1.25 g/ml "Concentration of Density Controlling Particles" Generally, the density controlling particle concentration shall be as small as possible in order to obtain as high a concentration of the active substance as possible. However, depending on the application, the density controlling particle concentration by volume is selected from a group consisting of: 1 - 95 % 1.5 - 75 %, 5 - 50 %, 5 - 40 %, 5 - 30 %, most preferred. "Dimensions of Fluid Bed Particles" In preferred embodiments, optimum dimensions of the fluid bed particles of the type used to carry out the present invention will largely depend upon the use to which they are to be put, although limitations dictated by the nature of the material and/or by the nature of the active substance and conglomerating agent within the fluid bed particles may also play a role. From the point of view of achieving the greatest rate of interaction of chemical species with a given mass of conglomerate of a particular type, it will generally be advantageous that the total surface area of the fluid bed particles is as large as possible, and thus that the size of the fluid bed particles is as small as possible. In preferred aspects of the fluid bed particles used to carry out the invention, the size of substantially all of said fluid bed particles is within a range selected from the group consisting of: 1-10000 µm, 1- 5000 µm, 1- 4000 µm, 1- 3000 µm, 1- 2000 µm, 1- 1000 µm, 50- 500 µm. The actual size range preferred is dependent on the actual application and the desired control of the dispersion properties, e.g. sedimentation and floatation, of the fluid bed particles both properties being dependent on the density and the size of the fluid bed particles. Thus, for very fast separation flow rates fluid bed particles of relatively low or high densities and relatively large sizes are preferred. However, large fluid bed particles may be limited in diffusion in certain applications, e.g. when proteins have to diffuse in and out of fluid bed particles and interact with active substances within the fluid bed particles. Further, for fluid bed particles having the same density and size, the diffusion properties of molecules within the fluid bed particles may depend on the number of density controlling particles. Thus, for fluid bed particles having one density controlling particle, the diffusion length may be shorter than for fluid bed particles having many smaller density controlling particles. In general, fluid bed particles of only one density controlling particle may be preferred when the molecular diffusion within the fluid bed particles is a limiting factor of the application. Thus, for purification and binding of proteins and other high molecular weight substances which may diffuse slowly in the fluid bed particles, e.g. in the conglomerating agent, the preferred size of fluid bed particles is within a range selected from the group consisting of: 1-2000 µm, 10-1000 µm, 50- 750 µm, 100- 500 µm, most prefered. Further, particularly for purification and binding of proteins and other high molecular weight substances in a batch process, the preferred size of fluid bed particles is within a range selected from the groups of: 1-2000 µm 250-2000 µm 500-2000 µm 500-1000 µm, most preferred. Further, for enzyme reactions in which an enzyme immobilized within the interior of the fluid bed particles reacts with a substrate of relatively low molecular weight, the preferred size of fluid bed particles is within ranges selected from a group consisting of: 10-10000 µm, 50- 5000 µm, 100- 3000 µm, 200- 1000 µm, most preferred. Especially for immobilisation of microorganims, the preferred size of the fluid bed particles is within ranges selected from the group consisting of: 0.5-50 mm 0.5-10 mm 0.5- 5 mm, most preferred. For fluid bed particles within the context of the present invention to be of use, for example, in chromatographic separation processes, the time-scale of the process of diffusion of fluid i.e. gaseous or liquid phases through the conglomerate, where relevant, should preferably be short in order to ensure sufficiently rapid equilibration between extra-and intraparticular phases; this time-scale will often be of the order of seconds. "Density Controlling Particles and Materials" In selecting density controlling particles for use as low or high density particles, the material of the particles depends on the purpose. Generally, the material is to be sought among certain types of natural or synthetic organic polymers, primarily synthetic organic polymers, inorganic substances and compounds, metallic elements, and alloys thereof, non-metallic elements, and gas bubbles. "Synthetic Organic Polymers" Among types of synthetic organic polymers which may possibly be of interest are resins of the phenol-formaldehyde type and ABS resins, but other classes of synthetic organic polymers, such as acrylic polymers, polyamides, polyimides, polyesters, polyethers, polymeric vinyl compounds, polyalkenes and substituted derivatives thereof, as well as copolymers comprising more than one such said polymer functionality, and substituted derivatives of such copolymers, may well furnish suitable candidates. Particularly preferred low density density controlling particles are hollow plastic particles. "Inorganic Substances and Compounds" However, from the point of view of cheapness and ready availability, in some cases it is advantageous to employ particles of inorganic material, especially since materials with the greatest mechanical rigidity are generally to be found amongst inorganic materials. Thus, material of the density controlling particles employed in the fluid bed particles may comprise a member selected from the group consisting of inorganic substances and compounds, metallic elements and alloys thereof, and non-metallic elements. In a preferred aspect, the material comprises a member selected from the group consisting of: anhydrous forms of silicon dioxide, including amorphous silica and quartz; metal silicates, including silicates of lithium, sodium, potassium, calcium, magnesium, aluminium and iron, and metal borosilicates, such as borosilicates of said metals, metal phosphates, including hydroxyapatite, fluorapatite, phosphorite and autunite; metal oxides and sulfides, including magnesium, aluminium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and silver oxides; non-metal oxides, including boric oxide; metal salts, including barium sulfate; metallic elements, including magnesium, aluminium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, indium, copper, silver, gold, palladium, platinum, ruthenium, osmium, rhodium and iridium, and alloys of metallic elements, such as alloys formed between said metallic elements; crystalline and amorphous forms of carbon, including graphite, carbon black and charcoal. "Gas Bubbles" Further, in a preferred aspect the material of the density controlling particles may comprise gases such as air, nitrogen, carbon dioxide, or inert gases, e.g. He, Ne, Ar, Kr, and Xe, confined in a cavity. "Siliceous Glassy or Ceramic Materials" The prior art discloses a number of examples of hollow particles of siliceous glassy or ceramic material which may be used as low density hollow particles of fluid bed particles, these previously disclosed particles being obtained relatively cheaply and straightforwardly by deliberate synthesis or as a fly-ash by-product of certain combustion processes. Accordingly, in a further preferred aspect of the invention, the material of the density controlling particles employed in fluid bed particles of both low and high density particles is a glass, preferably a synthetic glass comprising silicon dioxide and/or a silicate. In yet another preferred aspect of the invention, such material is a silicon dioxide-containing material derived from fly-ash, in which case the material may be amorphous (e.g. glassy) or crystalline, or to some extent both amorphous and crystalline. "Magnetic Materials" For certain applications of fluid bed particles, the material of the density controlling particles may comprise an appropriate amount of magnetic material e.g. for confining or retaining the fluid bed particles within a particular region of, for example, a process vessel or a chromatographic column, without the need for the incorporation of physical means of confinement or retention, such as a filter. Thus, a further aspect of the invention provides fluid bed particles of density controlling particles of which the particles comprise a component selected from the group consisting of: paramagnetic metallic elements, including iron, cobalt and nickel, and paramagnetic alloys, including alloys containing said paramagnetic metallic elements; metal oxides, including iron(II) oxide, iron(III) oxide, cobalt(II) oxide and nickel(II) oxide; metal salts, including cobalt(II) salts, e.g. cobalt(II) phosphate, chromium(III) salts, e.g. chromium(III) fluoride, and manganese(II) salts, e.g. manganese(II) carbonate. "Basic Particle Structure" Further, the material of the density controlling particles within the context of the present invention may be chemically and/or physically inhomogeneous. For example, it may have a layered structure involving one or more layers of similar or different materials, e.g. various types of siliceous materials. Alternatively, for example, it may consist of a siliceous material, such as a siliceous glassy material, containing particles or regions with a high content of a metal oxide or a metallic element chemically reactive, e.g. as a catalyst. "Active Substances" Concerning the active substances to be introduced into the fluid bed particles, this may, for example, be any type of material which is useful for a given application. Further, in one aspect of the invention the active substance may itself act as a conglomerating agent keeping the density controlling particles together and providing mechanical stability. In another aspect of the invention the material of an active substance comprises a member selected from the group consisting of organic and inorganic compounds or ions, metallic elements and alloys thereof, non-metallic elements, organic polymers of biological and synthetic origin, membrane-enclosed structures, biological cells, and virus particles. In a preferred aspect, the active substance comprises a member selected from the group consisting of: ligands known per se in the field of chromatography, e.g. charged species i.a. for ion exhange chromatography; proteins, dyes, enzyme inhibitors, specific ligands for specific proteins, e.g. biotin for purification of avidin and other biotin binding proteins, carbohydrates for purification of lectins or glycosidases, protein A, chelates, e.g. iminodiacetic acid; amino acids, e.g. arginine, lysine, and histidine; sulfated polymers including e.g. heparins; gelatins; benzhydroxamic acid; hydrophobic ligands, e.g. phenyl, hydrocarbons such as octyl amine, octanol; thiophilic ligands, i.e. divinyl sulfone activated substances coupled with mercaptoethanol or 4-hydroxy-pyridine, 3-hydroxy-pyridine, 2-hydroxy-pyridine; lipid vesicles; microorganisms and enzyme systems; virus particles, including attenuated and inactivated virus particles; natural and synthetic polynucleotides and nucleic acids, including DNA, RNA, poly-A, poly-G, poly-U, poly-C and poly-T; natural and synthetic polysaccharides and other carbohydrate based polymers, including agar, alginate, carrageenan, guar gum, gum arabic, gum ghatti, gum tragacanth, karaya gum, locust bean gum, xanthan gum, agaroses, celluloses, pectins, mucins, dextrans, starches, and heparins; natural and synthetic peptides and polypeptides and other amino acid based polymers, including gelatins, albumins, hemoglobulins, immunoglobulins including poly-and monoclonal antibodies, antigens, protein A, protein G, lectins, glycoproteins such as ovomucoids, biotin binding proteins e.g. avidin and streptavidin, and enzymes e.g. proteases, and protease inhibitors; synthetic organic polymers, including acrylic polymers, polyamides, polyimides, polyesters, polyethers, polymeric vinyl compounds, polyalkenes, and substituted derivatives thereof, as well as copolymers comprising more than one such organic polymer functionality, and substituted derivatives of such copolymers; food, medicals, and vaccines for fish and other animals living in water; hydrated and anhydrous forms of silicon dioxide, including silica gel, amorphous silica and quartz; metal silicates, including silicates of lithium, sodium, potassium, calcium, magnesium, aluminium and iron, and metal borosilicates, including borosilicates of said metals; metal phosphates, including hydroxyapatite, fluorapatite, phosphorite and autunite; metal oxides, including magnesium, aluminium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and silver oxides, and paramagnetic metal oxides, including iron(II), iron(III), cobalt(II) and nickel(II) oxides; metal salts, including barium sulfate, and paramagnetic metal salts, including combalt(II), chromium(III) and manganese(II) salts; metallic elements, including magnesium, aluminium, titanium, vanadium, chromium, manganese, indium, copper, silver, gold, palladium, platinum, ruthenium, osmium, rhodium and iridium, and paramagnetic metallic elements, including iron, cobalt and nickel, and alloys of metallic and paramagnetic metallic elements, including alloys formed between said metallic and paramagnetic metallic elements. "Introduction of Active Substance into Fluid Bed Particles" Generally, the active substance may be introduced into the fluid bed particles in a number of ways depending on the nature of the active substance, conglomerating agent, and the fluid bed particles themselves, e.g. their pore size. Thus, both low and high molecular weight ligands may be incorporated during conglomeration either by entrapment or by chemical cross-linking or by co-polymerisation. Further, both low and high molecular weight ligands may be chemically coupled to a conglomerating agent before or after conglomeration, or they may be coupled to precursor monomers or polymers introduced together with the conglomerating agent during the conglomeration provided the desired functions of the active substance is kept intact or may be reestablished before use. However, if the means of conglomerating damages or destroys the functioning of the active substance, the fragile active substance may be introduced after conglomeration provided the fluid bed particles have been designed with suitable pore sizes to allow access to their interior. "Introduction via Liquid Media" Materials within several of the above categories, for example lipid vesicles, virus particles, certain polypeptides, and certain metal silicates and other metal salts, may be introduced into the fluid bed particles in the form of solutions, suspensions or dispersions in suitable liquid media. "In Situ Formation/Sequential Introduction" Materials within some of the other categories, for example numerous polymers and copolymers, certain metal phosphates, certain metal oxides, e.g. silver oxide, and certain metallic elements, e.g. silver, may be introduced into the fluid bed particles by forming them in situ via a series of steps involving the sequential introduction into the fluid bed particles of a series of reagent solutions; for example silver oxide might be deposited in situ within fluid bed particles by partially infusing them with an aqueous solution of a soluble silver(I) salt, e.g. silver(I) nitrate, and then partially infusing them with an aqueous solution of a base, e.g. sodium hydroxide. The liquid solvent(s) may then, if desired, be removed from the fluid bed particles by, e.g., subjecting the fluid bed particles to a vacuum treatment. "In Situ Formation/Thermal Treatment" In some cases it may be possible to form an active substance in situ within the fluid bed particles by thermal treatment of a substance which has initially been introduced into or formed within the fluid bed particles via the introduction of one or more solutions, suspensions or dispersions in liquid media, although this obviously will require that the material of the fluid bed particles themselves and the conglomerating agent suffer no detrimental effects as a result of the thermal treatment; for example, it is well-known that the noble metals platinum and rhodium can be formed in finely divided, highly catalytically active form by heating almost any complex or binary compounds of the elements, e.g. (NH 4 ) 2 [PtCl 6 ] or (NH 4 ) 3 [RhCl 6 ], at temperatures above about 200 °C in the presence of oxygen or air. "Incorporation of Organic Polymers or Copolymers; In Situ Polymerisation" For the use of fluid bed particles in various chromatographic procedures, e.g. ion exchange chromatography, and in other procedures, for example solid-phase peptide synthesis, the fluid bed particles in question may incorporate organic polymers or copolymers. By way of example, the application of a permeable fluid bed to peptide synthesis employing the classical chemical methodology of Merrifield [see, e.g., Barany et al, Int. J. Peptide Protein Res. 30 (1987) pp. 705-739] will initially require the in situ formation of a cross-linked styrene/divinylbenzene copolymer resin by polymerization of styrene monomer containing, typically, about 1-2% of divinylbenzene; the resin may then be functionalized by subsequent treatment of the resin-containing fluid bed particles with solutions of the appropriate reagents. Thus, in a further aspect of a fluid bed particles, the active substance comprises a polymer or a copolymer formed in situ within the fluid bed particles by a procedure comprising the steps of: immersing the fluid bed particles in a solution, in a liquid solvent or solvent mixture, of one or more components which can polymerize or copolymerize to form a polymer or a copolymer or mixtures thereof, the solution optionally containing a polymerization catalyst or initiator, allowing the solution to at least partly fill the fluid bed particles via the through-going pores, allowing the polymer-/copolymer-forming components to polymerize/copolymerize to form solid polymer(s)/copolymer(s) therein, optionally substantially removing any liquid solution remaining within the fluid bed particles, optionally further treating the polymer-/copolymer-containing conglomerates as to: (i) at least partly chemically derivatize and/or modify the polymer(s)/copolymer(s) within the fluid bed particles and/or (ii) introduce further components into the fluid bed particles. "Incorporation of Fragile Active Substances" Materials other than those mentioned above may also conceivably be incorporated as components of porous fluid bed particles; for example, for certain biotechnological applications, such as the preparation of vaccines, antibodies or toxins, or cell cultivation for the production of metabolites (e.g. the production of ethanol by yeast cells) it may be desirable, according to the invention, to introduce live or dead cells of human, animal, plant, fungal or microoganism origin, or organelles (such as nuclei, mitochondria, chloroplasts or lysozomes) of similar origin, into fluid bed particles in situ . This will, of course, necessitate the provision of relatively large permeable fluid bed particles having through-going pores of a suitably large size, e.g. of the order of about 5-20 µm in the case of several types of human cells such as it will then often be necessary or desirable, after the introduction of such cells or organelles, to coat the resulting c fluid bed particles by a suitable treatment, so as to retain the cells or organelles within the fluid bed particles but allow migration of smaller species into or out of the fluid bed particles. This may be done by coating the fluid bed particles with a suitable membrane material having a suitable permeability. "Pore Sizes and Their Formation" The optimum size or size-range of the through-going pores will, of course, vary very considerably, depending on the use to which the permeable fluid bed particles is to be put. Such pore sizes are difficult to characterize quantitatively; however, in terms of the size of the molecules which are to be capable of passing through the pores, a realistic upper exclusion limit for macromolecules, notably biological macromolecules, such as proteins, will often be a molecular weight of the order of magnitude of 10 8 . The practical lower limit for pore size will generally be set by physico-chemical considerations, e.g. the detailed chemical structure of the outer part and the manner in which the outer part material dissolves or reacts during the pore-formation process. Although possibly rather difficult to achieve, the formation of through-going pores with sizes of the order of a few Ångström would be advantageous, in that the resulting permeable fluid bed particles in question would be expected to be applicable as so-called "molecular sieves"; for example, a typical application of permeable fluid bed particles with pores of this size would be as materials for removing traces of water from organic solvents, and the relatively large internal cavity volume of such fluid bed particles should confer a large drying capacity per volume unit of fluid bed particles. Pore sizes may typically be formed by methods known per se , e.g. by simply controlling the concentration of the conglomerating agent. Thus, for agarose or acrylamide-derivatives a larger concentration will provide a smaller pore size. However, other methods may be applied depending on the conglomerating agent and e.g. the incorporated polymers and copolymers. "Activation or Derivatization" In cases where the conglomerating agent may not have the properties to function as an active substance, the conglomerating agent, or agents, or polymers introduced in the fluid bed particles, may be derivatized to function as one or more active substances by procedures of activation or derivatisation well-known per se . Thus, materials comprising hydroxyl, amino, amide, carboxyl or thiol groups may be activated or derivatized using various activating chemicals, e.g. chemicals such as cyanogen bromide, divinyl sulfone, epichlorohydrine, bisepoxyranes, dibromopropanol, glutaric dialdehyde, carbodiimides, anhydrides, hydrazines, periodates, benzoquinones, triazines, tosylates, tresylates, and diazonium ions. "Conglomerating Agents" In selecting the conglomerating agent for use as a means of keeping the density controlling particles together and as a means for binding, entrapping, or carrying the active substance, the conglomerating material is to be sought among certain types of natural or synthetic organic polymers, and inorganic substances. "Organic Polymers" In one aspect of the invention the material of the conglomerating agent comprises a member selected from the group consisting of organic monomers and polymers of biological and synthetic origin. In a preferred aspect, the conglomerating agent comprises a member selected from the group consisting of: natural and synthetic polysaccharides and other carbohydrate based polymers, including agar, alginate, carrageenan, guar gum, gum arabic, gum ghatti, gum tragacanth, karaya gum, locust bean gum, xanthan gum, agaroses, celluloses, pectins, mucins, dextrans, starches, and heparins; synthetic organic monomers and polymers resulting in polymers, including acrylic polymers, polyamides, polyimides, polyesters, polyethers, polymeric vinyl compounds, polyalkenes, and substituted derivatives thereof, as well as copolymers comprising more than one such organic polymer functionality, and substituted derivatives thereof. "Inorganic Substances" In another preferred aspect, the conglomerating agent comprises a member selected from the group consisting of: hydrated and anhydrous forms of silicon dioxide, including silica gel, amorphous silica and quartz; metal silicates, including silicates of lithium, sodium, potassium, calcium, magnesium, aluminium and iron, and metal borosilicates, including borosilicates of said metals; metal phosphates, including hydroxyapatite, fluorapatite, phosphorite and autunite; metal oxides and sulfides, including magnesium, aluminium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and silver oxides, and paramagnetic metal oxides, including iron(II), iron(III), cobalt(II) and nickel(II) oxides; metal salts, including barium sulfate, and paramagnetic metal salts, including cobalt(II), chromium(III) and manganese(II) salts; metallic elements, including magnesium, aluminium, titanium, vanadium, chromium, manganese, indium, copper, silver, gold, palladium, platinum, ruthenium, osmium, rhodium and iridium, and paramagnetic metallic elements, including iron, cobalt and nickel, and alloys of metallic and paramagnetic metallic elements, including alloys formed between said metallic and paramagnetic metallic elements. "The Active Substance as Conglomerating Agent" In one aspect of the invention the conglomerating agent may be omitted in the sense that the active substance itself can function as a conglomerating agent. Thus, as mentioned, in a preferred aspect of the invention, the active substance may e.g. function as a conglomerating agent. In this case the conglomerating agent may comprise a member selected from the group consisting of: microorganisms and enzyme systems; natural and synthetic polynucleotides and nucleic acids, including DNA, RNA, poly-A, poly-G, poly-U, poly-C and poly-T; natural and synthetic polysaccharides and other carbohydrate based polymers, including agar, alginate, carrageenan, guar gum, gum arabic, gum ghatti, gum tragacanth, karaya gum, locust bean gum, xanthan gum, agaroses, celluloses, pectins, mucins, dextrans, starches, and heparins; natural and synthetic peptides and polypeptides and other amino acid based polymers, including gelatins, albumins, hemoglobulins, immunoglobulins including poly-and mono clonal antibodies, antigenes, protein A, protein G, lectins, glycoproteins such as ovomucoids, biotin binding proteins e.g. avidin and streptavidin, and enzymes e.g. proteases, and protease inhibitors; special synthetic organic polymers, including specifically designed acrylic polymers, polyamides, polyimides, polyesters, polyethers, polymeric vinyl compounds, polyalkenes, and substituted derivatives thereof, as well as copolymers comprising more than one such organic polymer functionality, and substituted derivatives thereof, special hydrated and anhydrous forms of silicon dioxide, including specifically design silica gel, amorphous silica and quartz; special metal silicates, including specifically designed silicates of lithium, sodium, potassium, calcium, magnesium, aluminium and iron, and metal borosilicates, including borosilicates of said metals; special metal phosphates, including specifically designed hydroxyapatite, fluorapatite, phosphorite and autunite; special metal oxides sulfides, including specifically designed magnesium, aluminium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and silver oxides, and paramagnetic metal oxides, including iron(II), iron(III), cobalt(II) and nickel(II) oxides; special metal salts, including specifically designed barium sulfate, and paramagnetic metal salts, including combalt(II), chromium(III) and manganese(II) salts; special metallic elements, including specifically designed magnesium, aluminium, titanium, vanadium, chromium, manganese, indium, copper, silver, gold, palladium, platinum, ruthenium, osmium, rhodium and iridium, and paramagnetic metallic elements, including iron, cobalt and nickel, and alloys of metallic and paramagnetic metallic elements, including alloys formed between said metallic and paramagnetic metallic elements; and other materials used as active substance provided they can conglomerate the density controlling particles. "Activation or Derivatization of Conglomerating Agents" However, in cases where the conglomerating agent may not have the properties to function as an active substance, the conglomerating agent may be derivatized to function as one or more active substances by procedures of activation or derivatisation well-known per se . Thus, materials comprising hydroxyl, amino, amide, carboxyl or thiol groups may be activated or derivatized using various activating chemicals, e.g. chemicals such as cyanogen bromide, divinyl sulfone, epichlorohydrine, bisepoxyranes, dibromopropanol, glutaric dialdehyde, carbodimides, anhydrides, hydrazines, periodates, benzoquinones, triazines, tosylates, tresylates, and diazonium ions. "Illustration of Fluid Bed Particles" Fig. 1A shows a 40X amplified photograph of aspherical fluid bed particles 10 having 1-2 mm of diameter and being prepared by distibuting unicellar glass microspheres 11 in conglomerating agarose 12 according to Example 1(a) Fig. 1B shows a 40X amplified photograph of selected spherical fluid bed particles also prepared according to Example 1(a). Fig. 1C shows a 40X amplified photograph of aspherical fluid bed particles 13 comprising a single solid glass sphere 14 and an acrylic acid copolymer 15 prepared according to Example 9. 5. EXAMPLES All solutions employed in the following examples are aqueous solutions unless otherwise indicated. EXAMPLE 1 Preparation of fluid bed particles based on 3M's unicellarglass microspheres "Glass Bubbles", B28/750, C15/250, and E22/400, [soda-lime-borosilicate] having a mean density of 0.28 g/cm 3 , 0.15 g/cm 3 , and 0.22 g/cm 3 , respectively. (a) Low Density Agarose Hollow Glass Spheres Fluid Bed Particles 300 ml soya bean oil was heated together with 3 ml sorbitane sesquiolate to 60 °C. 5 ml 6% agarose (HSA, Litex) in water was heated and 0.5 g hollow glass spheres (3 M, B28/750) having a mean density of 0.28 g/cm 3 were added under stirring. Following mixing of the agarose and glass microspheres the suspension was added to the soya bean oil under heavily stirring. The emulsion formed was stirred at about 60 °C in five minutes and cooled to 20 °C. The solidified agarose particles containing basic particles of hollow glass spheres were washed on a sintred glass filter with sufficient ether until all soya bean oil was removed. The conglomerate was then washed with water. The conglomerate had a low density and was floating on water. (b) Low Density Agarose Hollow Glass Sphere Fluid Bed Block Polymer Particles 300 ml 4% agarose was prepared by heating 12 g agarose (HSA, Litex) in 300 ml water. 9 g hollow glass spheres (C15/250, 3M) was added and the mixture was stirred until a homogeneous suspension was obtained. The suspension was cooled to 60 °C under steadily stirring and the fluid suspension poured on to an efficiently cooled surface. The agarose glass sphere suspension was gelated over a short period. The gel block had a homogeneous distributed content of hollow glass spheres. After cooling the gel block was blended and the granulate was sorted according to size and flow ability by means of "reverse sedimentation". (c) Low Density Polyamide Hollow Glass Sphere Fluid Bed Particles 5 g acrylamide and 0.5 g N,N'-methylenbis(acrylamide) were dissolved in 100 ml 0.1 M potassiumhydrogenphosphate-HCl, pH 7.0. 3 g hollow glass spheres (C15/250, 3M) were added under stirring. Following the formation of a homogeneous suspension a catalyst of 1 g ammoniumpersulphate and 0.5 ml N,N,N',N'-tetramethylethylendiamine was added for the polymerisation. Stirring was continued until a highly viscous suspension was formed. Following polymerisation the polymer block containing hollow glass spheres was blended as described under (b). (d) Low Density Gelatin Hollow Glass Sphere Fluid Bed Particles Five samples of 100 ml 5% gelatin (35 °C) in 0.15 M sodium chloride were added hollow glass spheres (E22/400, 3M) in increasing amounts: A: 0 g B: 2 g C: 5 g D: 20 g E: 27 g After adjustment of pH to 5.5 all samples were added 2.0 ml glutaric dialdehyde (25% solution, cat.no.: 820603, Merck) under thorough stirring. After 24 hours of incubation at room temperature the polymerized matrices were disintegrated in a blender. The resulting particles were separated from fines by reverse sedimentation (for A by sedimention as these particles were not floating). The particles were then collected on a glass filter and drained for excess water by vacuum suction on the glass filter. The wet but drained particles were then weighed and the particle volume determined by adding a known amount of liquid followed by determination of the total volume. The following particle densities were obtained: Measured Density: Calculated Density: A: 1.0 g/ml 1.00 g/ml B: 0.9 g/ml 0.93 g/ml C: 0.8 g/ml 0.85 g/ml D: 0.6 g/ml 0.63 g/ml E: 0.5 g/ml 0.57 g/ml (e) Low Density Gelatin Hollow Glass Sphere Fluid Bed Particles, and Immobilization of Horse-Radish Peroxidase 1 g of horse-radish peroxidase (grade II, Kem-En-Tec, Denmark) was dissolved in a solution of 100 ml 10% gelatin (cat.no.: G-2500, Sigma) and 0.5 M sodium chloride (35 °C). 10 g hollow glass spheres (B28/750, 3M) were added under stirring. After adjustment of pH to 5.5, 2 ml glutaric dialdehyde (25% solution, cat.no.: 820603, Merck) was added with thorough stirring. The resulting gel was incubated at room temperature for 2 hours and then disintegrated in a blender. The floating particles were separated from fines and non-floating particles by inverse sedimentation. The yield of wet, packed particles was approx. 120 ml. The size range was determined to be from about 200 to about 500 µm in diameter. (f) Low Density Gelatin Glass Sphere Fluid Bed Particles, and Immobilization of Yeast Cells 50 g bakers yeast cells were suspended in a solution of 100 ml 10% gelatin and 0.15 M sodium chloride at 35 °C. The suspension was added 20 g hollow glass spheres (B28/750, 3M). After adjustment of pH to 5.5, 2 ml glutaric dialdehyde (25% solution, cat.no.: 820603, Merck) was added with stirring. After two hours of incubation at room temperature the resulting block polymer was disintegrated in a blender and the particles were washed with 5 liters of 0.15 M sodium chloride. Non-floating particles were separated from floating particles by inverse sedimentation. Approximately 200 ml of packed floating particles containing yeast cells were obtained. The size of these particles spanned from about 150 to about 750 µm. The ability of the floating immobilized yeast cells to ferment glucose was evident from the evolvement of carbondioxide, when incubated in a 10% glucose solution. (g) Low Density Gelatin Glass Sphere Fluid Bed Particles, and Immobilization of Yeast Cells 50 g bakers yeast cells were suspended in 100 ml 10% gelatin (cat.no.: G-2500, Sigma), 0.15 M sodium chloride at 35 °C. The suspension was added 20 g hollow glass spheres (B28/750, 3M). After thorough mixing the suspension was cooled by pouring onto an ice cold glassplate making the suspension into a firm gel. The resulting gel was disintegrated in a blender and the particles washed with 5 liters of 0.15 M sodium chloride. Non-floating particles were separated from floating particles by inverse sedimentation. Approximately 200 ml of packed floating particles containing yeast cells were obtained. The size of these particles spanned from about 150 to about 750 micrometers. The ability of the floating immobilized yeast cells to ferment glucose was evident from the evolvement of carbondioxide, when incubated in a 10% glucose solution. (h) Low Density Agar-Gelatin Glass Sphere Fluid Bed Particles I 2 g agar (Bacto-agar, Difco), and 3 g gelatin (cat.no.: G-2500, Sigma) was dissolved in 100 ml 0.15 M sodium chloride by brief heating to the boiling point. After cooling to about 56 °C 10 g hollow glass beads (B28/750, 3M) were added. pH was adjusted to 4.0 with 5 M acetic acid followed by the addition of 2 ml glutaric dialdehyde (25% solution, Cat. No. 820603, Merck) with thorough stirring. The resulting polymer block was cooled to room temperature and incubated for 24 hours followed by disintegration in a blender. Floating particles were separated from fines and non-floating particles by inverse sedimentation followed by collection of the floating particles on a glass filter. The yield of floating conglomerate particles was 95 ml packed wet particles. (i) Low Density Agar-Gelatin Glass Sphere Fluid Bed Particles II 2 g agar (Bacto-agar, Gibco) and 3 g gelatin (cat.no.: G-2500, Sigma) was dissolved in 100 ml 0.15 M sodium chloride by brief heating to the boiling point. After cooling to about 56 °C 10 g hollow glass beads (B28/750, 3M) were added. The suspension was then cooled by pouring it onto an ice-cold glassplate. The resulting gel block was incubated for 24 hours at 4 °C followed by disintegration by blending in ice-water. The conglomerate floating gel-particles were separated from non-floating particles by inverse sedimentation and then collected on a glass filter. The yield was 105 ml of packed, wet particles. The particles were then suspended in 200 ml 0.1 M potassium phosphate buffer pH 6.5 and crosslinked for two hours by addition of 10 ml glutaric dialdehyde (25% solution, 820603, Merck). (i) Low Density Chitosan Glass Sphere Fluid Bed Particles A 4% solution of chitosan (Cat. No.: 22741, Fluka) was prepared by heating 12 g chitosan in 300 ml 10% v/v acetic acid. The viscous solution was cooled to about 40 °C followed by addition of 20 g hollow glass beads (B28/750, 3M). 3 ml glutaric dialdehyde was added (25% solution, 820603, Merck) with thorough stirring. The resulting polymer block was incubated for 24 hours at room temperature followed by disintegration in a blender. The conglomerate floating gel-particles were separated from non-floating particles by inverse sedimentation in 0.1 M sodium chloride and then collected on a glass filter. The yield was 400 ml of packed, wet particles with a diameter from about 200 µm to about 800 µm. (k) Vinyltriethoxysilan Coated Glass Spheres and Polyamide Fluid Bed Particles (A) "Coating of the glass spheres" 75 g (dry) hollow glass spheres (C15/250, 3M) were mixed with 500 ml 1% vinyltriethoxysilan solution in 0.1 M acetic acid and the suspension was stirred for one hour. The vinyltriethoxysilan solution was removed by filtration on a glass filter. (B) "Conglomerating acrylamide and glass spheres" 1.5 g N,N'-methylenbisacrylamide was dissolved in 10 ml ethanol and mixed with 8.5 g acrylamide dissolved in 90 ml water. 15 g vinyltriethoxysilan coated glass spheres, from (A), was added under stirring. 0.5 g ammoniumpersulphate and 0.5 ml N,N,N',N'-tetramethylethylendiamine was added as polymerisation catalysts after a homogeneous suspension was reached. The stirring was continued until the polymer block was formed. The polymer block was subsequently blended as described in Example 1(b) and "fines" were removed by "inverse sedimentation". This procedure resulted in approx. 100 ml low density conglomerate. EXAMPLE 2 Chemical Derivatisation of Low Density Agarose Glass Sphere Fluid Bed Particles 10 g (dried, wet weight) agarose conglomerate spheres containing hollow glass spheres from Example 1 were suspended in 100 ml 0.5 M potassiumphosphate/sodiumhydroxide pH 11.4. 10 ml divinyl sulfon og 50 mg sodiumborohydrid were added under stirring. The suspension was stirred at room temperature for three hours and the spheres were washed with water on a glass filter. The spheres were then activated chemically (i.e. a method out of many possibilities) and were ready for coupling of other substances. As an example mercaptoethanol was coupled for salt-dependent chromatopgraphy: The spheres were reacted with 5% mercaptoethanol in water that had been titrated to pH 9.5 with 1 M sodiumhydroxide for 3 hours at room temperature. The spheres were then washed thoroughly with destilled water and were ready to use in purification of proteins using salt-dependent chromatopgraphy. EXAMPLE 3 Purification of Human Immunoglobulin from Untreated Blood Using Fluid Bed Particles Prepared According to Example 2 100 g (dried, wet weight) divinylsulfon and mercaptoethanol treated agarose conglomerate spheres equilibrated with and suspended in 50 ml 0.75 M ammoniumsulphate were placed in a cylindrical glass column with an inner diameter of 5 cm and length of 10 cm. The glass column was sealed at the top and bottom using unscrewing plastic caps. The bottom lit had an outlet with a tube piping in the middle while the top lit had a corresponding inlet and a mechanical stirrer. The mechanical stirrer provides stirring through a air tight collar for stirring the conglomerate spheres contained in the column. The stirring propeller was designed to avoid fluid flow that carries the agarose conglomerate spheres down to the outlet in the bottom column. 2 l unfiltrated and not centrifugated human blood (i.e. outdated blood from a blood bank) having been added ammoniumsulphate to a final concentration of 0.75 M is lead through the column from the top with a flow of 10 ml/min under stirring with the abovementioned stirrer (i.e. to avoid the formation of channels through the fluid bed). 2000 ml of 0,75 M ammoniumsulphate was added at the same flow rate for washing non-bound proteins and particulates. Finally, the bound proteins were eluted from the conglomerate spheres by leading 500 ml of 0.1 M sodium chloride through the column. About 5 g human immunoglobulin was eluted in the sodium chloride fraction. Qualitative analysis showed a high purity of immunoglobulin having a very small contamination of albumin (< 1%). A corresponding purification of immunoglobulins with divinylsulfon and mercaptoethanol treated agarose spheres without hollow glass spheres was not possible in a traditionally packed column because of clogging of the column by the red blood cells and other sticky materials in blood plasma. EXAMPLE 4 Immunosorption Using Fluid Bed Particles Prepared According to Example 2 Agarose fluid bed particle spheres containing 4% agarose and produced as described in Example 1 were activated with divinylsulfon as described in Example 2. 10 g (drained, wet weight) activated gel was coupled to rabbit immunoglobulin by incubation of the gel over night with 20 ml rabbit immunoglobulin solution (10 mg immunoglobulin/ml in 0.1 M sodiumhydrogencarbonate/sodiumhydroxide buffer, pH 8.6 and 5% w/v polyethylenglycol MW 20,000). Excess active groups were blocked by incubation of the gel with 0.5 M ethanolamine/HCl, pH 9.0 for three hours. The gel was coupled with more than 80% of the added rabbit immunoglobulin. The floating conglomerate spheres having rabbit immunoglobulin attached could then be applied in an apparatus corresponding to the one in Example 3 for adsorption of anti-bodies against rabbit immunoglobulin from untreated serum of previously pure rabbit immunoglobulin immunized goats. The separated antibody was of a purity and activity corresponding to that obtained with conventionally packed columns using filtered and centrifuged antiserum. EXAMPLE 5 Preparation of Ion Exchange Fluid Bed Particles (a) Cation Exchange Fluid Bed Particles. Conglomeration of polyacrylic acid/acrylamide/N,N'-methylen-bis(acrylamide) and hollow glass spheres 300 ml destilled water was added to 25 ml acrylic acid, 100 ml ethanol, 10 g N,N'-methylen-bis(acrylamide), 25 g acrylamide, 2 g ammoniumpersulphate, 25 g hollow glass spheres (B28/750, 3M) and 2 ml N,N,N',N'-tetramethylethylendiamine. The mixture was stirred until a homogeneous suspension was achieved and then titrated to pH 8.5 with 5 M sodiumhydroxide under steadily stirring. Stirring was continued until polymerisation of the suspension ocurred. Following polymerisation the block was blended as described in Example 1 (b) and "fines" were separated by means of "inverse sedimentation". Following a thoroughly wash of the particles with water, 0.1 M HCl and 0.1 M NaCl, the content of carboxyl groups in the gel was determined to be about 250 µmol per g drained wet gel by simple titration. (b) Conglomeration of Acrylic Acid/acrylamide/N,N'-methylenbisacrylamide and Vinyltriethoxysilan Coated Hollow Glass Spheres 60 g (dry) hollow glass spheres (C15/250, 3M), 40 ml acrylic acid, 32 g acrylamide, 8 g N,N'-methylenbisacrylamide and 5 ml vinyltriethoxysilane was added to 300 ml distilled water. The mixture was stirred for one hour and brought to pH 7 with cold 27.4 % sodium hydroxide. 1 g ammoniumpersulphate and 1 ml N,N,N',N'-tetramethylethylendiamine was added as polymerisation catalysts and stirring was continued until the polymer block was formed. The polymer block was subsequently blended as described in Example 1(b) and "fines" were removed by "inverse sedimentation". In a batch protein binding assay, pH 9, 50 mM TRIS/HCl, 1 g of drained wet conglomerate was able to bind 96% of 190 mg offered lysozyme. (c) Conglomeration of Acrylic Acid/methacrylamide/N,N'-methylenbisacrylamide and Vinyltriethoxysilan Coated Hollow Glass Spheres Following the procedure described in Example 5(b), this ion exchange conglomerate was prepared as by using methacrylamide in exchange for acrylamide. In a batch protein binding assay, pH 9, 50 mM TRIS/HCl, 1 g of the resulting drained wet conglomerate was able to bind 92% of 190 mg offered lysozyme. (d) Conglomeration of Acrylic Acid/methacrylamide/N,N'-methylenbisacrylamide and Vinyltriethoxysilan Coated Hollow Glass Spheres Following the procedure described in Example 5(c), this ion exchange conglomerate was prepared as by using only 20 ml acrylic acid, 16 g methacrylamide and 4 g N,N'-methylenbisacrylamide, giving the conglomerate a lower dry weight content allowing larger proteins to diffuse in and out of the conglomerate. In a batch protein binding assay, pH 9, 50 mM TRIS/HCl, 1 g of conglomerate was able to bind 92% of 190 mg offered lysozyme. EXAMPLE 6 Immobilised Enzyme. Immobilization of glucose oxidase. Fluid Bed Particles Prepared According to Example 2 10 g divinylsulfon activated agarose conglomerate spheres from Example 2 were mixed with 20 ml of a solution of glucose oxidase from Aspergillus niger (10 mg/ml in 1 M potassiumhydrogenphosphate/sodiumhydroxide buffer, pH 10.5). The mixture was left for three hours and the uncoupled glucose oxidase was washed out of the spheres by 1 M sodium chloride. The enzyme coupled conglomerate spheres showed glucose oxydase activity with glucose as a substrate. The development of hydrogen peroxide was detected as a brown colouring of the gel and solution by coupling the reaction with peroxidase (horse-radish peroxidase) oxidation of orthophenylen diamine. EXAMPLE 7 Fluid Bed Particles Comprising Immobilized N-acetylglucosamine for the Separation of Wheat Germ Agglutinin Fluid bed particle spheres containing 4% agarose and produced as described in Example 1 (b) were activated with divinyl sulfon as described in Example 2. 10 g (dried, wet weight) of the activated gel was coupled to N-acetylglucosamine by incubating the gel over night with 20 ml 0.5 M potassiumphosphate/sodiumhydroxide buffer pH 11.5 containing 50 mg N-acetylglycosamine per ml. Following incubation the excess of active vinyl groups were blocked by 5% mercaptoethanol titrated to pH 9.5 by sodium hydroxide. The gel was washed thoroughly with 1 M sodium chloride. The binding capacity for wheat germ agglutinin was larger than 10 mg lectin per ml gel. EXAMPLE 8 Waste Water Treatment Using Immobilized Horse-Radish Peroxidase Floating immobilized horse-radish peroxidase fluid bed particles prepared as described in Example 1(e) were then used in a fluid bed for treatment of industrial waste water containing a range of phenolic amines and chlorophenols. The untreated waste water was added hydrogenperoxide to a concentration of 10 mM, pH was adjusted to 5.5 and the waste water was then pumped through a down-flow fluid bed column containing the floating immobilized peroxidase particles stirred proximal to the inlet as shown in Fig. 4. The bed of peroxidase fluid bed particles were divided into a turbulent zone in the upper part of the fluid bed (upper 7 cm) and a zone with particles in a stationary fluidized state (lower 20 cm) by stirring with a velocity of 50 rpm and adjusting the linear flow rate of the waste water. The enzymatic oxidation and polymerization of the phenolic compounds caused heavy precipitation in the effluent and after sedimentation of the precipitate, the content of phenolics in the waste water had decreased from about 100 ppm to about 10 ppm. The heavy precipitation of polymerized phenolic compounds would have made this procedure impossible to perform due to clogging in a traditional packed bed column. Further more, the use of a stirred fluid bed compared to a non-stirred fluid bed clearly showed less formation of channels through the bed and gave a more complete reaction. EXAMPLE 9 (a) High Density Acrylic Acid Copolymer Solid Glass Sphere Fluid Bed Particles To 300 ml destilled water was added 40 ml acrylic acid, 28 g acrylamide, 12 g N,N'-methylenbisacrylamide, 5 ml vinyltriethoxysilane and 245 g solid glass spheres (0.075-0.15 mm, Fryma, Switzerland). The suspension was stirred for one hour and then adjusted to pH 7 with cold 27.4% sodium hydroxide. 1 g ammoniumpersulfate and 1 ml N,N,N',N'-tetramethylethylendiamine was added as polymerization catalysts and the stirring was continued until a polymer block was formed. The polymer block was subsequently disintegrated in a blender followed by repeated sedimentation to remove fines. This procedure gave about 800 ml conglomerated particles with a density of 1.3 g/ml. In a batch protein binding assay (50 mM Tris/HCl pH 9.0) 1 g of wet but drained conglomerated particles was able to bind 61% of 190 mg offered lysozyme from hens egg white. Selected particles of these conglomerated particles having only one density controlling particle are shown in Fig. 1C. (b) High Density Gelatin Solid Glass Sphere Fluid Bed Particles Four samples of 100 ml 5% gelatin in 0.15 M sodium chloride (35C) were added solid glass spheres (0.075-.15 mm, Fryma, Switzerland) with a density of 2.5 g/ml in increasing amounts: A: 10 g B: 50 g C: 100 g D: 200 g After adjustment of pH to 5.5 all samples were added 2.0 ml glutaric dialdehyde (25% solution, Cat. No.: 820603, Merck) under thorough stirring. After 24 hours of incubation at room temperature the polymerized matrices were disintegrated in a blender. The resulting particles were separated from fines by sedimentation. The particles were then collected on a glass filter and drained for excess water by vacuum suction on the glass filter. The wet but drained particles were then weighed and the particle volume determined by adding a known amount of liquid followed by determination of the total volume. The following particle densities were obtained: Measured Density: Calculated Density: A: 1.1 g/ml 1.06 g/ml B: 1.3 g/ml 1.25 g/ml C: 1.5 g/ml 1.43 g/ml D: 1.7 g/ml 1.67 g/ml

Claims: A method of distributing a liquid in the fluid bed of a down-flow fluid bed reactor comprising a vertical reactor with an inlet, an outlet, and a fluid bed of particles CHARACTERIZED in a) that the particles and liquid proximal to the liquid inlet are agitated to divide the fluid bed into i) a turbulent zone having vigorously moving particles, and ii) a non-turbulent zone; said non-turbulent zone adjoining said turbulent zone; and b) that the extent of said turbulent zone is determined by a degree of agitation selected within a range from i) a degree of agitation providing turbulence only in the uppermost part of the fluid bed, ii) to but not including a degree of agitation providing turbulence of the particles throughout the fluid bed. A method according to claim 1, CHARACTERIZED in that the fluid bed particles are different for the turbulent zone and the non-turbulent zone. A method according to claim 2, CHARACTERIZED in that the fluid bed particles of the turbulent zone are inert particles of slightly different specific gravity than the particles of the non-turbulent zone. A method of distributing a liquid in the fluid bed of an up-flow fluid bed reactor comprising a vertical reactor with an inlet, an outlet, and a fluid bed of particles, CHARACTERIZED in a) that the particles and liquid proximal to the liquid inlet are agitated to divide the fluid bed into i) a turbulent zone having vigorously moving particles, and ii) a non-turbulent zone; said non-turbulent zone adjoining said turbulent zone; and b) that the extent of said turbulent zone is determined by a degree of agitation selected within a range from i) a degree of agitation providing turbulence only in the lowermost part of the fluid bed, ii) to but not including a degree of agitation providing turbulence of the particles throughout the fluid bed. A method according to claim 4, CHARACTERIZED in that the fluid bed particles are different for the turbulent zone and hie non-turbulent zone. A method according to claim 4, CHARACTERIZED in that the fluid bed particles of the turbulent zone are inert particles of slightly different specific gravity than the particles of the non-turbulent zone. A method as claimed in claims 1-3 or 4-6, wherein the particles comprise a) density controlling particles consisting of at least one low density particle providing flotation, and/or at least one high density particle providing sedimentation; and b) a matrix formed by consolidating at least one conglomerating agent for conglomerating said density controlling particles, with the proviso that said particles are not chromatographic adsorbent particles having covalently bound at least one active substance for binding molecules in a liquid chromatographic fluid bed process; and being constituted by a porous composite material having pores allowing access to the interior of the composite material of said molecules, (a) which porous composite material consists of a conglomerate having controlled density; said conglomerate consisting of: (i) at least two density controlling particles selected from the group consisting of low density particles having a density providing floatation and high density particles having a density providing sedimentation of the conglomerate in said liquid; and (ii) a matrix formed by consolidating at least one conglomerating agent selected from the group consisting of natural and synthetic organic monomers and polymers; said at least two density controlling particles being dispersed in said matrix; (b) which adsorbent particles have a controlled size range; (c) which density and said size range are selected to provide desired floatation/sedimentation properties of said adsorbent particles in the liquid in said fluid bed process; and (d) which at least one active substance is covalently bound to said matrix. The method according to claim 7, wherein the size range is controlled; and that their density and said size range are selected to provide desired floatation/sedimentation properties of said adsorbent particles in the liquid in a fluid bed process. The method according to claims 7-8, wherein there is more than one density controlling particle. The method according to any of claims 7-9, wherein said density controlling particles are impermeable to the liquid. The method according to any of claims 7-10, wherein the low density particles are hollow. The method according to any of claims 7-11, wherein the high density particles are solid. The method according to any of claims 7-12, wherein the density controlling particles constitute from 1 to 95 %, generally from 1.5 to 75 %, particularly from 5 to 50 %, preferably from 5 to 40%, and most preferably from 5 to 30 %, by volume of the fluid bed particles. The method according to any of claims 7-13, wherein the low density particles consist of hollow plastic particles, or unicellar glass micro spheres. The method according to any of claim 7-14, wherein the high density particles consist of glass particles, preferably glass micro spheres. The method according to any of claim 7-15, wherein the relative density is chosen from 0.1 to 15, particularly from 0.1 to 5, and preferably from 0.2 to 2. The method according to any of claims 7-15, wherein the realtive density is chose from 1 to 15, particularly from 1.1 to 5, and preferably from 1.1 to 2. The method according to any of claims 7-15, wherein the relative density is chosen from 0.1 to 1, generally from 0.2 to 0.95, particularly from 0.3 to 0.8, and preferably from 0.5 to 0.75. The method according to claims 7-18, wherein their size is within a range selected from the group consisting of 1-10000 µm, 1-5000 µm, 1-4000 µm, 1-3000 µm, 1-2000 µm, 1-1000 µm, 50-500 µm. The method according to claim 19, particularly for purification and binding proteins and other high molecular weight substances, wherein their size is within a range selected from the groups consisting of: 1-2000 µm, 10-1000 µm, 50-750 µm, 100-500 µm, most preferred. The method according to claim 19, particularly for purification and binding of proteins and other high molecular weight substances in a batch process, wherein their size is within a range selected from the groups of: 1-2000 µm, 250-2000 µm, 500-2000 µm, 500-1000 µm, most preferred. The method according to claim 19, particularly for enzyme reactions, wherein their size is within a range selected from the groups consisting of: 10-10000 µm, 50-5000 µm, 100-3000 µm, 200-1000 µm, most preferred. The method according to claim 19, particularly for immobilisation of microorganisms, wherein their size is within a range selected from the group consisting of: 0.5-50 mm, 0.5-10 mm, 0.5-5 mm, most preferred. A down-flow fluid bed reactor for use in carrying out the method claimed in claim 1, comprising a vertical reactor vessel with an inlet, an outlet, a fluid bed of particles and agitation means, said agitation means being located near or in the fluid bed proximal to the liquid inlet. An up-flow fluid bed reactor for use in carrying out the method claimed in claim 4, comprising a vertical reactor vessel with an inlet, an outlet, a fluid bed of particles, and agitation means, said agitation means being located near or in the fluid bed proximal to the liquid inlet.

Inventors: BOG-HANSEN THORKILD CHRISTIAN, LIHME ALLAN OTTO FOG, NIELSEN CLAUS SCHAEFER, BOG-HANSEN, THORKILD CHRISTIAN, LIHME, ALLAN OTTO FOG, NIELSEN, CLAUS SCHAEFER, Nielsen, Claus Schäfer
Applicants: UPFRONT CHROMATOGRAPHY AS, UPFRONT CHROMATOGRAPHY A/S
Application year: 1991
Main classification: B01J8
IPC codes: C02F3, B01J8, C02F1, C12M1, B01D15, B01J47, B01J20, B01J13, B01J2