DE7416409U - COMPONENT WITH AN ULTRA FILTER LAYER - Google Patents

Description

DR-ING. GERHARD SCHM ITT-N I LSO N """""ra ^ GRAM-AtoRESSE: inveotymonchen MK * £ NTANWALTE TELEX 8-29 βββ

G 74 16 4o9.3 August 12, 1977

Onion Carbide Corporation

a.Z .: J 058 times (Dr.S / we)

"Component with an ultra-filter layer"

Priority: May 10, 1973, No. 358 943, V.St.A.

The innovation relates to a component with an ultrafilter layer for the treatment of liquids. The innovation relates in particular to such a component for concentrating and senaring of components contained in liquids and for treating chemically stabilized emulsified oils and other liquids, which molecules with a *: large diameter contain.

A variety of ultrafiltration processes have been used recently described in the literature, with most of the work coming from the Oak Ridge National Laboratories of Atomic Energy Coitimission originated in the United States, where extensive studies of ultrafiltration or cross-flow filtration such as them is also mentioned, mainly in high pressure systems

7416409 08.1177

Pressures between 35 and 67 at have been carried out, using porous tubular support structures made of carbon or Alumino-silicates or a microporous membrane on a with Bored stainless steel liners were used.

It has been found that, for some aqueous systems, a bed of particles that are uniform on a porous substrate are dispersed, releases an effective filter medium, which prevents the passage of particles and molecules, their Size exceeds that of the openings between adjacent particles in the porous bed. It is believed that the on the substrate surface deposited particles may consist of any material which is opposed to the solutions that come in contact come with the surface is inert. A large number of materials were used, such as diatomaceous earth or kieselguhr, Perlite, asbestos fibers, cellulose fibers, dried silica gel and carbon.

Further experiments have shown that colloidal hydrous oxides can be used as penetration barriers for hyperfiltration in the reverse osmosis treatment of solutions, whereby solutes of even lower molecular weight can be concentrated in water, provided that the aqueous solution is below the surface of the permeable membrane High pressure between 3i5 and 70 at is pumped. In this case the colloids are formed from polyvalent metal salts by heating an aqueous solution of the salt until a cloudy or thick solution is obtained. To prepare the membrane, small concentrations of the thick solution (greater than 10 ppm) are circulated over the support structure at moderate speed and pressure. This procedure leads to the formation of a thin boundary layer with a thickness of up to 0.05 mm, which serves as an interface between the unused solution and the porous substrate (US Pat. Nos. 3,413,219 , 3 kk9 245, 3,537,988).

7416409 12/08/77

• ·

It is known, for example, that membranes formed from colloidal hydrous oxides retain their repellent properties for a day or longer, although the repellency gradually decreases (US Pat . No. 3 klj 219). The permanent presence of an additive in the solution improves the repellent properties and repairs defects that can occur in the membrane. In addition to the requirement of the permanent presence of an additive in order to maintain the desired properties, it has been found that many of the known processes can only be used for the treatment of certain types of liquids. Thus, until now, there has not been a completely satisfactory method of treating liquids containing chemically stabilized emulsified oils. Thus, although the prior art describes a variety of ultrafiltration processes, no fully satisfactory process has been known to date which avoids or minimizes many of the difficulties inherent in these processes.

The object of the invention is therefore to create an ultrafiltration device that is suitable for an economical continuous separation and concentration of components contained in liquids, such as Waste liquids from industrial processes can. In such liquids, the molecules with a relatively large diameter should be separated from those with a relatively small diameter * For example, large ones are dissolved Polymer molecules such as proteins, emulsified oil, dirt and to separate other suspended materials from solutions. Solutions can also be liquids used in textile production, from which, for example, polyvinyl alcohol is to separate. Other substances to be separated are materials such as those used in paper processing or in priming to be used with paints by electrical methods.

7416409 12/08/77

The invention also provides a method of coating the surfaces of the tubular parts which are in the Ultrafiltration device are included. The inner surfaces or outer surfaces of pipes made of carbon should be included a preformed metal oxide, preferably with zirconium dioxide, coated. Finally, there is also the sealing of the tubular parts in the ultrafiltration component to care.

To achieve this object, the ultrafiltration device for treating liquids has at least one component which has at least one inlet opening, at least one outlet opening and a zone with at least one outlet opening for collecting the material which has penetrated. The structural element also has a plurality of axially aligned hollow tubular members which are arranged in close proximity to one another in the collection zone. The parts have a pore volume of at least about 0.08 cm / g at the distribution tip in the pore diameter range. wherein the majority of the pores have a diameter of about 0.1 to e '. ^ a 2, o ^ i. The parts are held in the collecting zone and attached in a sealing manner so that Fluxα entering the component comes into contact with the parts. The corridor components which penetrate the walls of the parts are collected in the zone for the penetrated material. Onto a selected surface of the tubular members a substantially uniform, continuous adherent porous coating of preformed accumulated Metalloxydteilchen is provided, which has an average mean size of less than about 5.0 ^u. The thickness of the coating is about 0.01 to 10.0, the particles not penetrating substantially into the hollow parts; ho no more than 5, ο u. In combination with this component, the device comprises means for supplying a feed liquid to the component, means for drawing off a concentrated liquid from the component and means for drawing off the permeated liquid from the collecting zone for the permeated material.

7416409 08.12.77

Using the accompanying drawings, it will be found, for example explained in more detail.

Fig. I shows schematically an ultrafiltration arrangement.

Fig. 2 shows in perspective and partially cut away the ultrafiltration element with a plurality of tubes.

3 to 6 show details of the assembly of the tubular Ultrafiltration element.

Fig. 7 shows in longitudinal section one of the hollow tubular parts.

Fig. 8 shows in a detail in section the porous substrate and the Metailoxydbeschich + ong a tubular Part.

The ultrafiltration arrangement shown in Fig. I has an ultrafiltration element Io, a tank 12, pumps Ik and 16 and a valve control device ίο. The liquid to be concentrated and separated is pumped from the tank 12 via lines 2o, 22, 2k and 26 into the ultrafiltration element Io. As can be seen from Fig. 2, the structural element Io has a plurality of closely packed tubes 32 which are held in place by tube sheets J> h and 36 at each end. The tubes are arranged in the component in such a way that the liquid entering the component via line 26 must pass through the tubes. The liquid and dissolved phases of low molecular weight, ie molecules with a small diameter, penetrate the walls of the tubes, enter the chamber 38 and exit via the line 28. The dissolved phases of high molecular weight, ie molasses with a large diameter, as well as all of the undissolved material exits through line 3o.

7416409 08.17.77

Fig. 3 shows a device for positioning the tubes 32 in the jacket 40 of the component. The tube sheet 42 has a multiplicity of openings 44, the diameter of which for the Auinanme of the ends of the Kuiae ausi ciüüi · übe ** d.i.e Ε * · <Ι «η dsr Pipes are guided by O-rings 46, a plate 48 is placed over the pipe ends. On the tube sheet 42 is a cap 5o attached, compressing the O-rings to form a seal.

Fig. 4 _t 5 and 6 show another method of positioning the pipes 32 in the jacket of the device. The tube sheet 34 has openings through which the tubes 3 ² can be inserted. The outside of the tube sheet has openings whose diameter is larger than that of the tubes. This gives a recess for a seal 52, which can consist of rubber or a rubber-like material. In the component runner 565 shown in FIG. 4, which contains the tubes 32 and is provided with an opening 54 for the penetrated liquid, part of the end 58 is omitted so that one can see inside.

7 shows one of the tubular parts 32 in axial section. The feed liquid enters at point 60 and exits through the tubular element 32 to the point 62. The loosened Low molecular weight phases penetrate the walls 64 of the tubular member to the zone 66 for the penetrated Material.

Fig. 8 shows in a view enlarged approximately by a factor of 2ooo a part of the tubular part 32, for example at the point 68. The tubular part 32, which is for example a tube made of carbon, is composed of interconnected carbon particles 7o and has an im substantially continuous or uninterrupted stratification of closely packed metal oxide particles 72 .. The particles 72 penetrate only partially into the pores 74, which are for the

7416409 12/08/77

carbon tubes according to the invention are characteristic. j

The closely packed metal oxide particles typically penetrate to a depth H of no more than about 5, ο u a. The pores with a diameter of under

ί
about 0.05 jn are essentially free of dsm metal oxide coatings . During use, a filter cake 76 of dissolved phases of higher molecular weight, ie of molecules with a large diameter or undissolved particles, can form on the coated surface.

The component of the device can be so constructed and assembled that the metal oxide coating is either on the inner cavity surface or on the outer surface of the tubular parts is located. In each case the coating of the metal oxide particles is on the surface of the tubular part, which is in direct contact with the charge liquid, if, for example, the structural element; as shown in Fig. 2, where the feed liquid enters through line 26 and exits through line 3o, the metal oxide coating is on the hollow inner surface of the pipe parts. When if the coating is on the outer surface of the pipe sections, the feed liquid would flow through the Line 28 enter, contact the outer surface of the pipe parts and not from the component Io via one in FIG. 2 exit the line shown. The material which has penetrated and which has passed through the walls of the tubular parts can then be drawn off via the pipe 3 °.

Of these two types of construction of the element, the one shown in FIG. 1 is preferred because. the hydrodynamic properties are improved compared to the arrangement in which the feed liquid contacts the outer surface of the parts. The feed liquid goes through the inside Hollow part of the tubular parts therethrough. The penetrated material sits in the zone for the penetrated Material and can be withdrawn via line 28.

7416409 12/08/77

· ■■ Q _

The device according to the invention is suitable for operation over extended periods of time, with a high degree of Concentration and separation of the component * contained in the liquids is achieved. Unlike many Ultrafiltration arrangements - as they are currently used, the device according to the invention maintains a high throughput value without the need for additives.

The device according to the invention comprises an ultrafiltration element together with means for supplying feed liquid and means for collecting and withdrawing one Concentrate liquid and a permeated liquid. The component itself is also the subject of the invention; it comprises a plurality of axially aligned hollow tubular ones Parts which are arranged in a collecting zone of the component for the penetrated liquid. As shown in Fig. As can be seen, the tubular parts 32 are aligned in parallel and are sealingly held in place by tube sheets 34 and 36. The tubular elements can be made from a variety of Materials are made, but it is preferred that the material in the composition is inorganic to a large extent is. It has been shown that pipe parts made of inorganic substances are more resistant to abrasion or wear and tear and Withstand higher temperatures than pipes that are composed of organic materials on a larger scale. In practice it has it has been shown that tubular elements made of carbon, aluminum oxide or alumina, alumino-silicate or aluminum silicate and the like are suitable for use in the device according to the invention.

For successful work it is essential that the pipe parts have a precisely defined porosity. If the If the pore diameter is too large, no selective separation is obtained and the inner pores can be removed from the molecules be blocked with a large diameter. When the pore diameter is too small, the volume flow with the liquid

7416409 12/08/77

goes to the penetrated liquid collection zone, greatly reduced, thereby reducing the overall efficiency of the device.

It has been shown that tubular parts with a pore volume of at least about c, cS c ~ / g ir> r? sr distribution peak in the diameter range with a pore size defined by a diameter for the majority of the pores between approximately 0.1 and approximately 2, ο ii, for use in the ultrafiltration device are particularly suitable. Preferred are tubular parts made of carbon, in which the majority of Pores in the above diameter range. Pore size measurements on samples of carbon pipes used in building elements are used, show that a sharp point or a pronounced maximum in the range from 0.1 to 0.5 yu is available. Pores in this size range are counted for about 50% of the distribution over the pipe. The preferred tubular Parts are manufactured using a binding coking process followed by a heat treatment. Such pipes from Carbon are known and are used, for example, for the Manufacture of conventional ones with a ciii ^ m core Twisted arc candles for film projectors, with the carbon tubes serving as the outer jacket, with the Graphite and rare earth oxides are filled to produce the desired light intensity.

The size of the tubular parts and the ratio of length to diameter can vary within a wide range will. The selected particle size will undoubtedly depend on the overall size of the component as well as on the type of liquid and the components to be separated. In practice, however, tubular parts are used to make excellent ones Results used that have an inside diameter of about ο.25 cm to about 2.5 cm and a wall thickness of about 0.075 cm to about 0.63 cm and a length of about 12o cm to have. Tubular parts with an inside diameter of 0.6 cm and a wall thickness of about 0.15 mm are preferred and a length of about I2o cm *

7416409 12/08/77

- Io -

In addition to the precisely defined porosity of the tubular parts, it has been shown that an optimal ultrafixation can be achieved if the inner surface of the porous tubular parts with certain interconnected or caked metal oxide particles is coated, which will be explained below. The use of a metal oxide coating in a selected size range offers a considerable improvement over the prior art in terms of the development of microporous ultrafiltration filters for cross-flow filtration. Based on the use of Carbon, alumina or other substrate materials for the porous tubular parts with the addition of tightly packed or accumulated metal oxide particles, d. H. quote microporous Metal oxide coating, it has been found that several different effluents from industrial processes or waste water can be treated in which solids, colloids, oils or polymers with high molecular weight by ultrafiltration be separated with mass flows that are several times greater than with smooth pipes or the previously preferred Membrane made of hydrous zirconium oxide.

According to the invention, tightly packed metal oxide particles are used as the coating, which have a narrow size range below about 5 ρ and are present in large numbers between about 0.1 and about 2, ο u. The closely packed particles can further be classified as fine, with less than o, lu, as medium with o, l to l, ou and as coarse with l, ou and larger. Preference is given to tightly packed metal oxide particles in which a proportion of at least about 50 % has a size between about 0.1 and about 1.0.

Although commercially available metal oxide powders can be used, in some cases they require long meals, to reduce the particle size to the appropriate range.

Preferred metal oxide powders which have proven particularly suitable for the use according to the invention are powders, according to the so-called "precursor process"

7416409 12/08/77

if «1 ·

are made. In this procedure, a Metal compound brought into contact with a carbohydrate-containing material and the material ignited to keep the carbohydrate to decompose and remove some material, and to convert substantially all of the metal compound to ensure fragile agglomerates of the metal oxide. This is followed by chopping or grinding of the agglomerates thus formed in order to accumulate the finer microporous ones used in the present invention Particle Receives.

For example, a batch of the metal oxide powder mass produced by the preliminary process, for example zirconium dioxide, which contains about 8 to 10 % yttrium oxide, can be ground in a ball mill, with 1500 g placed in a container with a capacity of about k 1 and Zirconia balls are added. The container is then filled to about 3/4 with deionized water and acidified with acetic acid until a pH of k is reached. Then the contents are ground for about 18 hours.

The particles produced by the precursor process are so small that the settling rates are slow. Therewith masses that are not completely crushed by the balls during the wet milling can be removed from the disperse suspension the released particles can be separated by sedimentation, centrifugation or other separation processes based on based on particle size or mass. For example, a size classification by centrifugation from a wide distribution of particle sizes are effected in order to obtain closely packed metal oxide particles, which in large Number are within the desired range. When the separation is carried out, the released particles, which remain in suspension, suitably by treatment which reduce the surface charge and make the colloidal suspension unstable.

7416409 08.1177

• 4

Typical treatments are d ± 3 adding an acid to the Lowering the pH of the suspension, or adding salt, which has a polyvalent anion. Treated in this way Suspensions return to a state of flocculation * In this form the powder can be removed from the bulk of the suspended The medium can be separated by filtration or sedimentation.

It has been shown that the mean size of the individual particles, including the masses with the preferred sizes from o, i bi3 i, o u., under l.o u and usually is below o, l u. The individual particles are not resolved at a magnification of 1000 times. Sine X-ray diffraction of the powder has a final particle size in the range of about 0.1 to about 0.1.

A variety of metal oxide particles can be used as the coating according to the invention. The metal of the metal oxides can be used for : I or in mixtures beryllium, magnesium, calcium, aluminum, titanium, strontium. Yttrium, lanthanum, zircon, ifefnium, thorium. Be iron, manganese, silicon and the like "

If the metal oxide powder used is zirconium dioxide, in some cases the zirconium dioxide powder is preferably used a stabilized form. Therefore it can be a yttrium, calcium, magnesium, rare earth metal or another known metal compound, which is a stabilizing oxide forms, can be used together with the zirconium dioxide-containing compound in the manufacture of the covering material. the Proportions of the zirconium dioxide compound and the compound of the stabilizing metal are chosen so that the desired Type of stabilized zirconium dioxide is generated.

7416409 12/08/77

Further details of the preliminary stage procedure for esteem of metal oxide powders are explained in the prior art (Belgian PS 766 962).

The metal oxide coating is in practice on the tubular Parts applied by passing an aqueous suspension of the accumulated particles through the tubes linear flow velocities of about 0.15 m / s to

2

about 12.2 m / s and at pressures from 2.1 kp / cm to 35 kp / cm. The concentration of the accumulated particles in the suspension is in a range from about 10 to about 100 mg / l. The suspension is generally kept at a pH which is sufficient to maintain a stable suspension of the additives. Since water filters through the pores of the pipes, the particles are filtered out and cover the pore opening of the substrate with a very fine-pored layer. This uniform, uninterrupted, highly porous, but very fine-pored structure results in a higher throughput and improved resistance to soiling or clogging compared with bare pipes or pipes that are coated with less porous substances. For optimum efficiency and optimum throughput, the coating must have a thickness of between about o, have oil to about Io u without substantial penetration into the tubular portion of greater than about 5 ^»u ° is present. As a possible measure, but not mandatory, the tubular parts can be coated at pressures that are at least equal to the operating pressure of the component and at flow rates that are not greater than that of the operating state of the component.

For most purposes the tubular parts are coated with the closely packed metal oxide particles. ro that one average coating of about 1.3 mg / cm of the surface of the tubular part receives. For certain purposes, a second coating can be applied to the top

7416409 12/08/77

the first coating of the small size particles in addition be applied.

For the majority of applications it has been shown that a 's'srt votl et-'"0; 15 ^m Z of closely packed metal oxide particles per

2
cm of surface area is the minimum amount to be used.

Higher amounts give higher and more stable flow values. For example, while a medium metal oxide coating of

2
1.32 mg / cm is useful, a coating of for example

2
4.6 mg / cm would be desirable.

The coating of the tubular parts with the metal oxides (!. ") Is preferably carried out within a selected pH range. The particular pH range chosen is the range in which the metal oxide particles remain in suspension. For example, when the tubular parts are coated with zirconia particles the preferred pH range is between 1 and about 5 and preferably between about 2 and about 3.5 uas adjustment the pH value can be adjusted by adding acidic, for example Acetic acid, oxalic acid, hydrochloric acid and the like. In practice, oxalic acid or hydrochloric acid is preferred, as they tend to keep any iron in solution.

In contrast to the known processes, it is not necessary in the invention to form a colloid on the surface of the tubular part before the metal oxide is deposited, as is described, for example, for water-containing zirconium dioxide (US Pat. No. 3,413,219). The metal oxide compositions are prepared beforehand and separated into suitable particle size ranges before coating. The coating is mainly a mechanical measure in which the metal oxide agglomerations penetrate to a certain degree into the pores of the tubular particles and form the desired coating on the surface. The closely packed metal oxide particles do not "fill" the pores of the tubular members in the sense that they

7416409 12/08/77

become clogged, but "bridge ¹¹ the pores, so that molecules of the feed stream of smaller diameter can pass through them at a high speed.

The Ultrat'iitiervorrichtung according to uöi? Invention can, vic previously mentioned, work effectively at pressures of about 35 kgf / cm and lower. Various factors, such as temperature, the pressure and the flow rates vary depending on the particular feed stream. Additionally is the actual geometrical configuration of the interior of the tubular part is also a factor. For example, the interior of the parts does not need to be cylindrical, but rather can be star-shaped, hexagonal, octagonal, sawtooth-like or the like.

It has been shown that the concentration and separation of certain dissolved phases give optimum results received when the hollow tubular parts containing the metal oxide coating with an additional coating are covered, for example with a metal oxide powder of fine quality (<o, l 11) or a water-containing zirconium dioxide gel. A method of applying an aqueous zirconium dioxide gel as a coating is known (US Pat. No. 3,537,988).

Such coatings are in addition to the metal oxide coating. The attempted use of water-containing zirconium oxide gels alone on the tubular parts do not allow the high degree of concentration and separation according to the invention. Examples k and 5 given later are directed to the use of the ultrafiltration device for the concentration of polyvinyl alcohol in textile liquids. As set out in Table V of Example 5, the metal oxide-coated carbon tube and the tubes which contain an additional hydrous metal oxide lead to noticeably improved results compared to uncoated carbon tubes,

7416409 12/08/77

* ■

- 16 -

As shown in FIG. 8, a filter cake initially forms on the coated pipe parts during operation Molecules of larger diameter and composed of solids or suspended matter in the feed liquid. When the ultra-filtration device is working, the oeschickungaaticm, for example an aqueous Ql emulsion. passed under pressure across the filter surface at speeds great enough to cover most of the accumulated Shear off filtered substances. Since this flow is perpendicular to the direction of flow of the filtered liquid through the Filtering area is called "cross-flow" filtration used. It is essential that the Menganstrom through the tubular Parts is so large that one reaches turbulent states · The liquid should pass through the tubular parts with one velocity of at least 0.3 linear meters per second and a Reynolds number of at least about 2,000.

For example, eiii'i ultrafiltration device with a single component that has approximately 15ί tubular parts an inner diameter of 0.63 cm;.;. <.. i a length of 122 cm has, per day at a pressure of 7 kp / cm and a temperature of the feed stream of about 22 C above Process l2ooo 1.

When two or more components are used in the same device or when the number of tubular parts is increased, multiples of 4o,000 liters can be effectively processed per day.

With conventional filtration, the filtered material would develop into a thick filter cake which would greatly reduce the rate of filtration. Depending on the geometry of the system and the type of material to be filtered, the speeds parallel to the filtering surface range from about 0.15 m / s to about 12 m / s. It is essential for the method according to the invention that the filter interface is designed in such a way. that dissolved, colloidal or

suspended particles of the feed liquid in the Size range from Io u and larger down to o, oo2 u can be removed with filter throughputs through the area can that multiples of ^ oocl per m and day for a Pressure of 7 kp / cm and less.

Although ultrafiltration is used to remove suspensions, Has used colloids and high molecular weight materials dissolved in aqueous solutions, comes the finding that oil emulsions by ultrafiltration d by coated fine-pored pipes from the bulk of the aqueous Phase can be concentrated and separated from, completely surprising. Such emulsions are for example at the production of steel, as a coolant in rolling mills and as a lubricant or for cutting, drawing, punching or used in other metalworking operations. In addition, it can also include the types of oil, water, dirt and metal filings existing emulsions that can be used when washing finished Metal parts and the like with chemical cleaning agents receives, to an oil, dirt + to the particles withholding Solution, clean water, and a dissolvable detergent filtrate phase.

Currently, collections of. Oil, dirt and various other suspended particles in an aqueous system by adding acid and / or other chemicals at relative removed at high temperatures to break the emulsion and separate the oil from the suspension. The water is left in it to settle the particulate matter in large storage tanks to remove. The remaining soluble components are either neutralized or otherwise through Addition of acid or alkali treated chemically in another way and then brought to a discharge device or transported to a suitable unloading or processing point. Transportation is relatively expensive. In no case

are water-soluble components of the wastewater clean for the return to the cycle is separated. Besides, they are Chemical treatment costs significant both in terms of materials and labor and in terms of of the treatment facilities. The wastewater discharge charges for water phases that have been mixed with chemicals are often very high. Environmental protection laws prohibit dumping in an increasing number of communities. This leads to a further treatment of the aqueous phase is required before the water itself can be released.

The ultrafiltration process according to the invention can reduce the volume of the oil-dirt-water phase by a factor of 5 to 3 ° or higher, which depends on the oil content of the starting material. As a result, the volume of the material, which has to be treated further for the discharge, is very much reduced. Since the oil level in this concentrate phase can usually be brought to 20 to ko% , which is sufficiently high to maintain combustion without additional addition of fuel, the problem of removal by burning can be greatly simplified. This also recovers most of the oil's thermal energy.

The oil-free aqueous phase can be discharged into a sewer or returned to the cycle. Reuse of the water favors a closed cycle, which is highly desirable from the point of view of water conservation is. If valuable water-soluble substances are present, for example detergents, together with the filtrate go through it, the profitability of the operation is also increased realized by avoiding the loss of these materials with the wastewater stream.

Another great advantage that results from the use of the method according to the invention for the continuous removal of dirt and oil from a metal washing device,

7416409 12/08/77

for example a dyeing or painting line, results in is that the detergent washing liquid usually uses the cleanliness of the following rinse and others. Pre-staining baths improved. As a result, the quality of the paint or lacquer coating on the metal part can be improved considerably.

The invention is also directed to the ultrafiltration element itself and to methods of marring the tubular members. Although a single tubular element can cause concentration and separation, it is of course convenient to construct a structural element with a plurality of tubes. The number of tubular members used can vary depending on a variety of factors. Components with 25 or less or up to a thousand or more tubular Parts were constructed ready-made.

As shown in Fig. 2, the tubular parts are aligned in parallel and in close proximity to one another. Each tubular part is held in place by the tubular sheets Jk and 36. The tube sheets themselves are arranged in the component in such a way that they form a zone 38 for the liquid which has penetrated and which is sealed against the packing fluid which enters through the inlet opening via the line 26. The only liquid which can penetrate into the penetrated liquid zone is the liquid which is filtered through the walls of the tubular parts.

The outer shell of the component and the tube sheets can be made from a variety of materials, for example from a wide variety of plastics, such as Polyvinyl chloride and the like, or of metals such as stainless steel. Due to the wide variety of liquids, which are treated, and the temperature changes of the feed streams, the component is preferably made of

Stainless steel or any other material that is compatible with the feed liquid and the operating conditions is tolerable.

Figures 3 and k show two types of methods of assembling the tubular parts in the tube sheets so that a liquid-tight seal is achieved. In both cases the ends of the tubular parts are sealed and dampened by a rubber or rubber-like seal. In contrast to a glued or otherwise attached audio sound device, the installation according to the invention provides a "freely movable seal" so that brittle, tubular parts, for example parts made of carbon, can withstand a certain shock load.

In the arrangement shown in Figure 3, O-rings 46 are used. fitted over the ends of the tubular members. The plate 48 is then placed over the pipe ends and O-rings. When the cap 5o is attached to the end plate 42, the O-rings are compressed and seal and secure the tubular parts in place.

FIGS. 4 to 6 show a preferred assembly of the tubular parts in the ultrafiltration element. As shown in Fig. 6, the end plate 34 has openings with a sufficient diameter for feeding the tubular parts. The surface of the end plate opposite the zone for the penetrated Liquid is provided with recesses so that a seal 52 is placed over the end of the tube and in the recess surface can be pressed. This poems and secures the tubular parts in their position. There is an advantage to this assembly over that previously described in that the tubular parts can be arranged in alignment very close to one another. For specific uses and as a result of v,. Space requirements, it can be advantageous to have a relatively compact or space-saving component without having to give up the desired number of tubular parts.

7416409 12/08/77

With extremely effective use of the ultrafiltration device in accordance with the invention one often uses a closed loop system, i. H. the feed stream becomes after passing through the component in which a slightly higher concentration of molecules with larger molecular weight is achieved, led back to the component. When the liquid is brought to a sufficient concentration it can be withdrawn from this system - a variety of automatic controls can be used can be used to remove the concentrate and to circulate the feed stream.

Although in Fiy. 1 shown ultrafiltration device only a single component Io is used, it can be used for certain For purposes of use, it may be desirable to use two or more components in the same device. In these Cases can the components in Rei? ^ be arranged, d. H. the concentrate from a first component serves as a feed stream for a second component, etc. A parallel arrangement can also be made in which the same Feed stream enters all components at the same time. The arrangement is affected by a variety of factors including the concentration and separation of the components for a optimize specific application.

As a result of the excellent properties of the invention The device is particularly suitable for the separation and concentration of components in a wide variety of Liquids are included. A particularly favorable application of the ultrafiltration device consists in concentrating and Separation of oil-water emulsions, which has already been mentioned. These emulsions appear in a wide variety in metal processing and metal cleaning. A Satisfactory process of effective concentration such liquids to reduce the waste to be disposed of to a minimum and to avoid many of the useful Recovering components in the fluids was heretofore

7416409 12/08/77

not known. However, the device according to the invention is extremely successful in treating a wide variety of liquids which may be emulsified and / or contain chemically stabilized oil

As will be shown in the examples below, the ultrafiltration device can also be used for concentrating and Separating solutions from the textile processing industry can be used. For example, polyvinyl alcohol can easily can be concentrated and separated from sizing solutions used in textile processing with a high degree of efficiency.

The device 3iger * t is also suitable for the recovery and Return of reagents from a large number of wash waters, for example from car washes, cleaning companies and like that.

The ultrafiltration device can also be used for electrophoretic coating. For example, after a painted object has been removed from an electric dye bath, in many cases it is sprayed with water to remove the excess print from the bath. When this color-containing washing water is passed through the device according to the invention, the color solids can be returned in concentrated form to the dyebath. The device is also suitable for removing excess water, soluble salts or excess solubilizers from d. _; sm dye bath. As shown in Example 6, the pigment phase rejection can be 99.95 % . In contrast to known processes (US Pat. No. 3,663,399), the penetration speeds or penetration throughputs achieved with the device according to the invention are considerably greater.

In addition, the apparatus has been found to be useful in handling a variety of food and beverage products suitable. For example, the device can be used for

7416409 12/08/77

Concentration and separation of spent grain liquids in the production of beer and ale, for Concentrating proteins from cheese whey, clarifying vinegar and the like can be used. In seawater desalination, the ultrafiltration device according to the invention can be used as the first stage for cleaning the Vassex * vor- dcääcü Performed by a reverse osmosis unit. After all, the area of application remains the ültrafiltriervorrichtung nor the concentration and separation of bovine blood serum, protein, enzymes and the like to call.

The invention is explained in more detail with the aid of the following examples.

example 1 An aqueous solution, solution A, is approximately soft

2 Geifi- ^ metallic foreign bodies and soluble oils with about

Containing 3% by weight of soluble industrial detergents and sodium hydroxide is passed through an ultrafiltration element circulated at different pressures and flow rates. The waste product itself comes from that Storage tank for an industrial washing system, which is used to remove dirt, metal chips and oil residue from metal parts remove upon completion. There are various oils on the finished parts, namely lubricating oils for drawing, soluble oils from forming, and various cutting oils from machining. the Concentration of the total oil in the feed is controlled by adding sulfuric acid and then separating it definitely. The operating conditions and the results obtained are summarized in Table I below.

7416409 12/08/77

- hi ι: t ■ t ι ·> ·

Table I.

Operating conditions of the ultrafiltration system for the treatment of the oil-water-detergent solution A:

Operating pressure 7 kp / cs ^ Circulation speed 5 | 5 m / s Filtrate flow 37oo l / m day Operating temperature 6o ° C

total operating time 3o h

Characteristics of the feed, the filtrate and the Concentrates:

Feeding the filtrate concentrate

PH value 12, VJi I 12th 3 , 5 12, 5 Oil content 2 % <loo ppm 16 ϊί Detergent content 3 % % 3 %

From Table I it can be seen that the charge is eight times as high Had concentration. The filtrate has less than 100 ppm oil, however, it still has the same detergent concentration as the feed, making it suitable for reuse.

Example 2

A second oil-water detergent solution, Solution B, is examined in which the major oil component is soluble oil used in a metal stamping operation (the detergent phase is Amchem lool). In this case the feed stream contains from about o _t 4% by volume of oil, which is detected by ..Schwefelsäureseparierung. The operational characteristics and the characteristics of the feed, des

.j The filtrate and the concentrate are summarized in Table II.

'{set * There were flow values of more than dloo l / m per day

H over operating periods of more than 30 days with different

7416409 12/08/77

«■« «kl

Oil concentrations detected. One reaches a 55-fold Concentration.

Table II

Properties of the ultrafiltration system for the treatment of the oil-water-detergent solution B:

2 operating pressure 7 kp / ctn

Circulation speed 4.6 m / s

Operating temperature 66 C

Filtrate flow 4660 l / m day

■ total operating time 72o h

Characteristics of the feed, the filtrate and the Concentrates:

] PH value 3e dispatch 5 ; Filtrate concentrate Oil content 9, k 9.5 9.5 Detergent content O, % \ loo ppm 22 % Example 3 3 3 % 3 %

The third attempt uses a soluble oil (Texaco Soluble Oil C) in a single pipe system with a feed concentration of about 5 % . The data in Table III shows the operating characteristics for a 30 hour trial. During this time the oil concentration is increased from 5 % to 2o % .

7416409 12/08/77

. 26 -.: - ■ · .. · ■■■ '* ^:

Table III

Operating conditions of the ultrafiltration system for the treatment of an oil-water emulsion:

Operating pressure 7 kp / cm

Circulation speed 6.7 m / s

ο mean filtrate flow 5640 l / m day

mean operating temperature 54 C

total operating time 24 hours

Characteristics of the feed, the filtrate and the concentrate:

Feed filtrate concentrate oil content 5 % { loo ppm 29 %

Example 4

To illustrate the versatile application of the ultrafiltration system for various other industrial waste products, tests are carried out on samples of polyvinyl alcohol-water solutions at concentrations of 1.0 to 4.0% . The data in Table IV shows the operating characteristics of the system and the characteristics of the feed, filtrate and concentrate. The polyvinyl alcohol is within a molecular size range of 50,000 to 1,000,000, as used in sizing baths in textile processing. In this case a coating of zirconia is coated as a particulate bed with a second coating of an aqueous zirconia gel. The aqueous zirconium dioxide is produced by boiling an 0.25 molar ZrOCl solution over 30 η to hydrolyze the oxychloride. In the case of a 9 ^ cm long tube with an internal diameter of 6.4 mm, 12.5 ml of this solution are added to 3 liters of distilled water to make the charge.

7416409 12/08/77

2
which is passed through the pipe at 7 kgf / cm for about 1 hour.

The permeated liquid is returned to the reservoir in order to deposit the hydrous zirconium dioxide gel on top of the previous layer. The device ensures a rejection of more than 97 % polyvinyl alcohol. '

Table IV

Operating conditions of the ultrafiltration system with a polyvinyl alcohol solution :

2 Operating pressure (overpressure) 7 kp / cm

Circulation speed 6.1 m / s

mean filtrate flow ₂

at 1 % concentration 286o l / m day

2 at 4 % concentration 86o l / m day

average operating temperature 82 C

total operating time 112 h

Characteristics of the feed, the filtrate and the concentrate:

Feeding the filtrate concentrate

pH 6.8 6.8 6.8

Polyvinyl alcohol i % o, o3 % 4 %

'Example 5

There are comparative tests for the concentration of polyvinyl alcohols performed with uncoated carbon tubes, with carbon tubes made with a particulate Coated and made with carbon tubes that come with a bed particulate bed plus the hydrous zirconia

are coated. All measurements are made at 7 kp / cm inlet pressure and a flow velocity in the vicinity of 6.1 m / s

7416409 08.1177

,, · a ι ι: "· JJ

executed. The data in Table V shows a comparison of the repellency and plus properties of the three trials, which shows a much improved flow due to the zirconia particles and the improved repellency with a sustained high flux when the hydrous zirconia gel layer is added.

Table V

Comparison of rejection and flow properties for a Penetration device consisting of a carbon tube, from a carbon tube with a particle bed and from a carbon tube with a particle bed and hydrous Metal oxide, with a 1 Ji-polyvinyl alcohol solution as Beschi kung is used.

River ₂
in l / m
Ta « Rejection
in % temperature
ln ° C Carbon tube
alone 6 Λ ο to 5ο 56 Carbon tube
Particle 4o9o 63 to 66 87 Carbon tube
T «silchen-
hydrous
Metal oxide 4o9o 97 to 99 8o Example 6

The ultrafiltration device is used for the concentration of a primer paint from an electrodeposition system used. A porous carbon tube with a pore volume of about 0.2 g / cm, with the majority of the pores being in the diameter range vo.i o, l to l, o u, which is through

2 Hg porosity measurement is determined, is 6 mg / cm

coated by precursor ZrO_ particles obtained by centrifugation for a size range from o, l to l, c u

7416409 12/08/77

have been classified. The coating is carried out in that about 3 liters of acidified water are added to _{the ZrO 0 and}

2 That the water is circulated through the inside of the pipe at 7 kgf / cm for one hour while the water penetrating through the pipe wall is supplied to the circulating feed. The pipe is then inserted into a circulation system, which a 7 »5 % solids solution of an electrodepositable paint (Forbes 2ooo) at 7 kp / cm and 27 ° C through the pipe at a linear flow rate of 4.6 to 7» 6 m / s is fed. Over a period of 214 h, the permeation flow rate is maintained between 3480 and 4090 l / m day. In other experiments with this color and shape, extending over 412 more hours, the flow becomes

ο
Maintained between 2o5o and 265o l / m day. The rejection of the pigment phase is 99 »95 % and the ionic constituents 48.8 %. Typical penetration rates for Filra ultrafiltration systems of this type of color are 150 to 130 l / m day.

Example 7

Another high porosity powder for high surface area is used as the precoat, namely a slurry of V ™ alumina ground to approximately the same size range as the precursor zirconia, ie

on o, l to l, o u. The carbon tube has the same construction

- 2 as in the previous example. The river at? kp / cm with pure water at 43 C amounts to over 1,6400 l / m day. With the Pre-coating falls to an operating temperature of

7I ⁰ C to Il45o l / m ^a day. This tube is used for the treatment of a sample of the black liquor or waste liquor from wood pulp digestion. You get flows in the order of magnitude of 2860 to 3270 l / m day with a color repellency of more than & ls 90 %

and a Jo% rejection of the ionic constituents

7416408 12/08/77

C ·

• · t

- 3ο -

Example 8

The experiment is carried out with black liquor or drains when processing paper. A carbon tube, as described above, is coated with isilehenin-iges »J-jr and then with hydrous zirconium dioxide from the ZrOCl„ solution according to Example k . After the test with the black liquor was carried out overnight at 7 kp / cm and 60 ° C., the penetration rate is 327o l / m "day, the repellency of the paint being more than 90 % . The charge has a conductivity of 32,000 mhos the permeated liquid has a conductivity of about 17000 mhos, with an ionic rejection of the order of k7% being indicated.

Example 9

It becomes a comparison on a number of carbon tubes and alumina tubes carried out to the wide variety of To show properties that relate to pore diameter, pore volume, and air and water permeability relate. As stated above, it has been found that tubular parts with a pore diameter of about o, l to about 2, ο ii, like samples 1 to 7 of Table VI, ensure optimal concentration and separation of the components from liquids.

These tubular elements have pore diameters that are in are generally greater than about 2, ο u (sample 8 to 15), however, the deep pores tend to be clogged with the metal oxide particles and the ultrafiltered ones. Materials in the retained material so that undesirably low penetration rates are obtained. When the bulk of the The pore volume has pore diameters of less than about 0.111, the water throughput is also the uncoated Pipe so low that the rate of penetration doesn’t get one

7416409 12/08/77

has an acceptable low value. In contrast, the samples corresponding to numbers 1 to 7 have a pore volume in

the distribution peak of about 0.08 cm / g or greater, where

the pore diameter range mainly between about O ₁ I,

and e * "~.? .rs! j lier-t. which gives you excellent results

receives. Such carbon tubes also differ there-; j

by having a bulk density of less than about 1.6 g / cm · The sample no. 7 concerns a tubular part made of aluminum oxide or alumina, while the other tubes are made of Consist of carbon. All measurements are made under standard conditions to determine the pore volume, the pore diameter, the air and water throughputs and the filling density.

7416409 12/08/77

Per-
No. . · TABLES VI Pore through
knife in u
(Top)
from ... to O.39 Pore volume
o, l to
o, 5 u £ Iji
cnr / g cm "/ g 0.036 Air-
through-
casual-
at
o, 7 atü
in 2
cm / min cm Te: llen 22nd 7oo Fill
density
in
g / cm- * Ul * • * 1 Total
tes
Pores
volume
in ,
cnr / g 0.18 o, 44 0.16 o, o31 13th Water flow b «i
7 kg / cm ₂ 111
l / m day
1 min 5 in: Ln ... 1.39 to
I. , 2 o, 2o Porosity properties of uncoated tubular shapes o, 19 o, 5 0.16 0.038 13th 22 500 1.39 3 o, 2o top
of
Pores
volume
in
cnr / g o, 2 0.8 o, l4 o, ol - - - CD 4th o, 19 0.16 o, 2 o, 5 o, li 0, <> 4 - - 9 82o 1.53 5 o, 13 0.16 o, 2 o, 5 0.06 0.05 6th - 13th ■! L2o 1.51 - CD 6th o, 13 o, 15 o, 3 1.8 o, o5 0.05 11th 13 080 ... l, 5o 5 » 7th o, 12 o, l3 o, 7 88 0, ool 0.11 179 18 4oo 8th 794 2.55 12th 8th o, l4 o, o9 7.1 12th o, oo4 0.13 13th - 8th S ₇ O 1.66 - »a 9 o, 15 0.08 2.2 12th o, oo4 0.11 3o 28 630 5 730 1.61
1.65 Io o, 135 0.11 2.4 12th 0.005 0.11 85 89o 8th 330 1.63 11th o, 135 0.06 3.1 12th 0.003 0.11 34 77 300 13th 74o 1.64 12th 0.13 0, Io 7.4 12th 0, oil 0, Io 47 57 260 2o <i5o 1.67 13th o, 125 0, Io 2.9 12th 0.003 0, Io 25th 94 o7o 5 235 1.66 14th o, 12 0, Io 8.8 12th 0, ool 0, o4 22nd 49 080 22nd 490 1.67 15th o, ll 0.08 1 0, oo2 25th 32 4oo 0.07 o, o7 81 800 0.07 o, o4

- 33 Example Io

The ultrafiltration device is used for the concentration and separation of the protein fraction of curd whey from the mass of water, lactose and dissolved salts. £? tiSirdoi: porous Koiilftnstoffrohre with pore volume in the said preferred range used, which ^{are coated with a •:} precursor '''- magnesium aluminum spinneret according to Example 6. A feed solution containing 90 % extracted liquid phase is passed through the device for 20 hours at a temperature of k *) ° C , with substantially all of the protein being kept in the concentrate. The penetration rate at the end of the experiment is 2 ^ 50 l / m day. The tubes are then cleaned with distilled water, then new feed solution is passed through the device. After 6.5 hours of operation, the penetration rate drops from 2o8o to 135o l / m day. After washing with a detergent (Tergitol I5-S-5), a penetration rate of the charging solution of 2330 l / m day is achieved again. The tubular parts are then cleaned with the detergent and cleaned with 0.6 atmospheric steam to sterilize the tubes and remove particulate matter.

The device is then reloaded with feed solution, the initial penetration rate is 2580 l / m day. After 2 hours of continuous operation the penetration rate is 2o9o, after 24 h

2
ΙΛ70 l / m day. From this it can be seen that the tubular part and the metal oxide coating can be cleaned with steam and sterilized, so that one can return to the high performance.

7416409 or 12.77

t * (! ti · · I

«· T Cf t · · I I

- 34 -

However, the invention not only relates to an ultrafiltration device, to a component for use in particular in an ultrafiltration device according to the invention, to a method for sealingly securing and holding the tubular elements in the .Bauelement according to the invention, as well as a method for coating the tubular parts of the component according to the invention.

Rather, the invention also relates essentially expressly to all processes for concentrating and separating oil from oil-containing liquids, in which the inventive The ultrafiltration device or the component according to the invention is used.

In particular, the invention also expressly relates to a method for concentrating and separating oil from oil-containing liquids, in which the oil-containing Liquid of an ultrafiltration device according to the invention supplied and a liquid enriched with oil is withdrawn from the device according to the invention. Furthermore, the invention also expressly relates to a method for concentrating and separating oil from liquid containing oil and detergents, in which the liquid containing the oil and detergents is a ultrafiltration device according to the invention and a liquid enriched with oil from the device is deducted.

The invention also relates to a method for concentrating and separating emulsified oil from Liquids which contain emulsified oil, these liquids being an ultrafiltration device according to the invention fed and a liquid enriched with oil is withdrawn from the device.

7416409 12/08/77

• * »f III · I * · · »T · *» «14

• I »· §. *. Il * IMl

• • tit »i

• M || «Trri · I

- 35 -

Furthermore, the invention also relates to a method for concentrating and separating polyvinyl alcohol from Liquids of the textile industry which contain polyvinyl alcohol, the liquid containing polyvinyl alcohol being a Ultrafiltration device according to the invention is supplied and a liquid enriched with polyvinyl alcohol from the

Device is withdrawn. ........ ...

The invention further relates to a method for Separation and concentration of a dye pigment from electro-dye bath fluids that contain color pigment characterized in that the liquid containing the color pigment is fed to an ultrafiltration device according to the invention and a liquid enriched with color pigment is withdrawn from the device according to the invention.

Furthermore, the invention also relates to a method for concentrating and separating pulp from liquids, which Contain pulp, these liquids being fed to the ultrafiltration device according to the invention and one with paper pulp enriched liquid is withdrawn from the device.

The invention also relates to a method for concentrating and separating used grain liquids from liquids containing used grain liquids, these liquids being fed to an ultrafiltration device according to the invention and a liquid being drawn off from the device ¹ which is enriched with used grain liquids.

The invention also expressly relates to a Process for concentrating and separating protein fractions of curd cheese whey from the bulk of the liquid, which is water, Contains lactose and dissolved salts, the liquid containing the protein of the ultrafiltration device according to the invention is supplied and a liquid from the device

7416409 12/08/77

·· ■ »(til · · 1

- 36 -

is withdrawn, which eats enriched with the protein portion.

Expectations

7416409 12/08/77

Claims (1)

Union Carbide Corporation u.z .: J 058 times (Dr.S / k / we) Protection claims 1. Component with an ultrafilter layer for concentrating and separating components in liquids, consisting of a microporous base layer with a microporous. Metal oxides containing coating on the to be filtered Side facing the liquid, characterized in that the base layer (32) has a pore volume of at least approximately 0.08 cnr / g in the maximum distribution of the pore diameter knife range, in which most of the pores with a diameter between about 0.1, u and about 2.0.a, and that the metal oxide particles (72) of the coating having an average median size of less than about 5.0 µ are preformed and in close pack with an accumulated coverage of about 0.01 -u to about 1OyU adhere to the base layer without significantly penetrating into it . 2. Component according to claim 1, characterized in that at least 50% of the pores (.., The base layer (32) a 7416409 08.1177 nil r · · · · · Average pore diameter within a range of about 0.1μ to about 0.5μ. 3-. Component according to Claim 1 or 2, characterized in that the metal oxide particles (72) have an average mean size between approximately 0.1 u and approximately 1.0 u. 4. - ,. Component according to claim 3; marked by an overcoat of metal oxide particles (72) having an average particle size of less than about o, 1 µ. 5. The component according to claim 4, characterized in that the overcoating of hydrous zirconium dioxide consists. 6. Component according to sinem of claims 1 to 5, characterized characterized in that the metal oxide particles (72) are zirconia. 7. Component according to one of claims 1 to 5, characterized in that the metal oxide particles (72) from y aluminum oxide. 8. Component according to one of claims 1 to 5, characterized in that the metal oxide particles (72) from 7416409 12/08/77 ■ - 1 '-' '* Made of magnesium — aluminum oxide spinel. S- components according to one of claims 1 to 8, there characterized in that the base layer (32) is made of carbon Confess. '" 10. 'Component according to one of claims 1 to 8, (... characterized in that the base layer (32) consists of aluminum oxide. 11. Component according to one of claims 1 to 8, characterized in that the base layer (32) consists of aluminosilicate. 12.. Component according to one of Claims 1 to 11, characterized in that the base layer (32) is tubular <- and the coating is provided on the inner and / or outer jacket surface of the base layer. 13. The component according to claim 12, characterized in that the ratio of length to diameter of the formed tubular portion is at least about 2o: 1. 14. Component. _{According to} claim 12 or 13, characterized by an inner diameter of about 0.25 to about 2.5 cm of the tubular part. 7416409 08.T2.77 4 ('«» ti <req. <»■ · * t 15. Component according to one of claims 12 to 14, characterized in that at least two tubular parts are arranged one behind the other. [ 16. Component according to one of claims 1 to 15, characterized in that the provided with the coating Side of the base layer (32) to an inlet chamber that tangentially supplies the liquid to be filtered and the other side the base layer is connected to a collecting chamber for receiving the liquid that has penetrated through the ultrafilter layer. 17. Component according to claim 16, characterized in that; that the exit of the entrance chamber again with its entrance connected (22,24,26,30). 18. The component according to claim 17, characterized by drrch a bleed line connected to the inlet chamber (at 18). 19. Component according to one of claims 12 to 18, characterized in that the base layer is formed by a closely adjacent tube bundle, the tubes (32) of which are held in a sealed manner between tube sheets (34, 36). 20. Component according to claim 19, characterized in that 7416409 12/08/77 that the tube sheets (34,36) have openings through which the tubular parts (32) protrude at a radial distance, and that the radial distance through expandable ring seals (44; 52) is filled, which are compressed in the respective opening in the tube sheet and their normal inner diameter compared to the Outside diameter of the associated tubular part is undersized. 21. The component according to claim 2o, characterized in that the radial distance between the openings in the tube sheet (34,36) of an end-face annular recess of the respective opening and the ring seal (52) is arranged in the ring recess is (Fig. 5,6). 22. Component according to Ansprnrr 2o or 21, characterized in that the ring seal (44; 52) consists of rubber. 23. Component according to claim 2o or 21, characterized in that the ring seal (44; 52) consists of a synthetic, rubber-like material. 24. Construction lines tjnach claim 2o or 21, characterized in that the ring seal (44; 52) consists of metal. 7416409 12/08/77