NO802575L - APPARATUS FOR AA WEEK OR REDUCE AIR OXYGEN CONTENT, PROCEDURE FOR ITS MANUFACTURING AND PROCEDURE FOR ITS OPERATION - Google Patents

Description

The invention relates to an apparatus for increasing or decreasing the proportion of oxygen in air to be supplied to a consumer, in particular a combustion chamber, using a very thin semi-permeable membrane that separates a first chamber, which has a higher pressure and has an inlet for normal air and an outlet for 02-lean air, and another room, which has a lower pressure and has an outlet for C^-enriched air, and further also relates to a method for manufacturing this apparatus and a method for its operation.

In the case of a known device of this kind, particularly intended for enriching inhalation air or combustion air with oxygen,

used a membrane that is more permeable to oxygen

than for nitrogen and consists of silicone rubber, and which is placed flat on the surface of a porous carrier. The membrane areas which

can be achieved in that connection are small, which means that only small amounts of C^-enriched air can also be obtained. Admittedly

is it possible to increase the amount by increasing the differential pressure. But such a pressure increase is unfortunate for many applications and

is also only possible in all cases for technical reasons

to a limited extent.

Furthermore, a dialysis apparatus for blood purification is known where porous hollow fibers in a number lower than 10,000 are combined into a cylindrical bundle and arranged in a cylindrical capsule. The fiber ends are led sealed through the end walls of the capsule. Blood is conducted through the interior of the hollow fibers. In its peripheral surface, the capsule has an inlet at one end and an outlet at the other end for cleaning liquid which is pumped through the space outside the hollow fibers in the capsule. In this case, the toxins migrate from the blood into the cleaning fluid, not as a result of any difference in pressure, but as a result of a difference in concentration. In order for the toxins to have sufficient time to penetrate into the cleaning liquid, the hollow fibers have a length of 220-350 mm.

The invention is based on the task of providing instructions for an apparatus of the kind indicated at the outset, with which it is possible in connection with small dimensions to process air in larger quantities and/or with lower pressure differences, so that it is particularly suitable for supplying combustion chambers .

According to the invention, this task is solved by the hollow fibers with a microscopic wall exhibiting the membrane on a peripheral surface and are arranged parallel to each other in large numbers in a capsule whose opposite end walls the ends of the hollow fibers pass through, at the same time that these ends are sealed on their outer circumference.

As the inner or outer peripheral surfaces are provided with a membrane, an extremely large membrane area is produced. It is therefore possible to produce a small amount of C^-enriched air, e.g. for breathing purposes, with very small pressure differences, e.g. depending on lung power, or with normal pressure differences of approx. 2 To get very large amounts of C^-enriched air, e.g. combustion air for a motor vehicle or a boiler. The microporous wall provides a sufficiently stable substrate for an ultra-thin membrane.

The hollow fibers can here form a carrier to which the membrane is applied. This makes it possible to use a hollow fiber with optimal load-bearing properties. But the hollow fibers can also consist of the membrane material, so a structure is obtained in one piece with a porous support part and a non-porous membrane. In that case, the membrane does not need to be placed afterwards, as it can already be produced during the manufacture of the hollow fibres, whether this happens by controlled pore formation or by closing the pores along a peripheral wall. Furthermore, a particularly good connection is obtained between carrier and membrane. Optionally, the hollow fibers can also have reinforcement inserts in their wall.

Appropriately, the inner cavity of the hollow fibers forms the first space and the space in the capsule outside the hollow fibers the second space. As the inner cavity in the hollow fibers leads to higher pressure, an insignificant elastic expansion of the hollow fibers will indeed be able to take place, but no compression and thus associated reduction of the passage cross-section.

There must be at least 100,000 hollow fibres, preferably more than 0.5 million hollow fibres. Devices with more than 5 million hollow fibers can be realized without difficulty. In particular, so many hollow fibers should be arranged approximately parallel to each other in a hollow fiber battery that a membrane area of 15-500 m<2> appears.

Particularly advantageously, the hollow fibers are arranged in a capsule, at the same time that at least one outlet collector space extends along a capsule side wall which runs parallel to the hollow fibers. The 02-enriched air can thus be sucked away to the outlet collection chamber mainly across the hollow fibres, so the throttling resistances become relatively small.

In particular, it can be ensured that the capsule has rectangular end walls with a relatively long and a relatively short side, and that the outlet collecting space extends along a capsule side wall which extends between the long sides of the end walls, and essentially over the entire area of this wall. Furthermore, another, similar outlet collector space can extend along the opposite side wall. In this way, it is ensured that all the hollow fibers are connected

with an outlet collection room via a relatively short path. This also means that the pressure drop between the membrane and the outlet manifold is correspondingly small. As the hollow fibers are not completely straight, even though they are tightly packed, they leave sufficiently large intermediate channels for the gas. Optionally, however, such channels can also be constructively conditioned by a corresponding arrangement of the hollow fibers or by the use of hollow fiber sections with a larger diameter.

Preferably, the hollow fibers have an outer diameter of 100-400 pm, preferably around 200 pm. Taking into account the achievable wall thicknesses, a sufficiently large internal cross-section is obtained which does not offer too much flow resistance to the air flowing through.

The hollow fibers do not need to have a wall thickness greater than 20 µm, and even less than 6 µm is sufficient. This provides sufficient stability in connection with minimal resistance to the penetrating air.

It is recommended to keep the length of the hollow fibers as small as possible, especially less than 200 mm and preferably 100 mm, so that air with a sufficient proportion of oxygen is offered to the membrane part at the rear end of the hollow fibers.

When it comes to the pores of the hollow fibres, it must be taken into account that, firstly, they must be small enough not to influence the safe repulsion of the membrane, but secondly, they must be large enough not to inhibit the gas transport from or to the membrane to an unfavorable degree. In this connection, it is advantageous if the pore size is broadly in the range of 0.1 µm to 1 µm. Preferably, the pore size decreases towards the membrane. The small pores

in order to make better use of the membrane, they only need to extend over such a thin layer that they do not significantly influence the gas transport. In particular, the size of the pores covered by the membrane can be 10 to 50 nm.

In a preferred embodiment, it is ensured that the membrane sits on the inner circumference of the hollow fibres. This gives a particularly long service life because the membrane is well protected and you avoid any mechanical stress that can occur with overlapping hollow fibers with an external membrane.

Furthermore, it is advantageous to insert an air filter in front of the inlet to the first room. This ensures that the inner cavity of the hollow fibers does not become clogged.

When installing in a motor vehicle, the hollow fibers should stretch

in its longitudinal direction and have one end close to the front of the vehicle. Thus, it is possible to utilize the speed wind to drive the air through the hollow fibers when the effort is to use oxygen-enriched combustion air in the engine.

A bellows can also be used to drive the air through the cavities of the hollow fibres. This can also be additionally built into a motor vehicle.

If the combustion chamber is part of an internal combustion engine or a combustion plant, the membrane area should be chosen so large that the combustion temperature is above 2,500°C, especially at approx. 3,000°C. The high combustion temperatures lead to an increase in efficiency and a reduction in fuel consumption. In the case of combustion

machines, it is also superfluous to allow the air-fuel ratio to vary depending on full load and partial load, whereby carburettor construction and supervision is greatly simplified. As the ignition speed is very high, the ignition time can be set to close to top dead center. This means an addition to the saving of fuel and reduces the tendency to self-ignition. The reduced propensity for knocking also makes it possible to increase the compression, whereby the degree of efficiency is further increased. Thanks to the rapid ignition sequence, uneven heat transfers to the combustion chamber wall are further avoided, which leads to a lower cooling water temperature and less ventilator effect. In addition, the rapid ignition sequence provides a smooth running of an internal combustion engine. The amount of combustion air required for the operation of such a combustion chamber is admittedly very large. For example, for a two-litre engine it amounts to over 100 m 3/h. A correspondingly large membrane area can, however, be provided without difficulty using the hollow fibres.

Furthermore, it is advantageous if there is a device assigned to the combustion chamber's exhaust gas channel to reduce the proportion of nitrogen oxide. Thus, account is taken of the fact that at the high combustion temperatures aimed for, a large amount of nitrogen oxide is obtained, e.g. 5 volume percent at 2,700°C. All in all, this results in a device that corresponds to a normal combustion plant (supply of fuel and normal air, exhaust gas with a low content

of harmful substances), but a significantly better degree of efficiency with a corresponding saving of fuel.

For example, the exhaust gas channel in its first part may have thermal insulation which slows down the cooling of the exhaust gases and thus favors the decomposition of nitrogen oxide. Another possibility consists in assigning the exhaust gas duct at least one device for reaction-free exhaust gas heating.

A method for producing an apparatus where the hollow fibers are provided with a membrane is, according to the invention, characterized in that the hollow fibers are first produced and then treated with a coating liquid containing the membrane material, after which this is cross-linked onto the hollow fibers. The coating liquid can be easily applied to the peripheral surfaces of the hollow fibers. A dosage to achieve the desired membrane thickness is also possible.

In order to achieve particularly thin membranes, it is recommended that the coating liquid contains a dissolving or dispersing agent for the membrane material and that this agent is then removed. In particular, a dissolving or dispersing agent should be used which can at least partially escape through the pores of the hollow fibres. The molecules must therefore be smaller than these pores. This enables an internal coating. With an external coating, the speed with which dissolution or the dispersant can be removed.

The removal of the solvent or dispersant can e.g. happen by applying a pressure difference between the inside and outside of the hollow fibres. Instead of or at the same time as this, the solvent or dispersant can be removed by evaporation or evaporation. It is often advantageous if the cross-linking of the membrane material is initiated already before the coating treatment. As larger molecules already occur below, it is easier to remove solvent through the hollow fiber wall without the membrane material being taken along at the same time. The coating liquid may also contain a catalyst. In this there can also be a pre-nighter component. Another possibility is to supply the hollow fiber rafts to be coated beforehand with a cross-linking component or also to let the hollow fibers consist: of a material that exhibits active groups that cause cross-linking. If the catalyst-equipped membrane material has good flowability, it is also possible to use it directly as a coating liquid.

The application can e.g. happen in such a way that the hollow fibers are moved past an application station for the coating liquid. They can also be dipped in the coating liquid or preferably sprayed with it.

A particularly favorable opportunity lies in the production of

the internal cavity during the manufacture of the hollow fibers å

introduce a filler containing membrane material into the fiber material.

According to the invention, a method for operating the device is characterized by the fact that by enriching the combustion air with oxygen in the combustion chamber, a combustion temperature of more than 2,500°C is provided, and that the cooling of the exhaust gases leaving the combustion chamber occurs more slowly in a temperature range of at least 200°C than in a subsequent temperature range. At the combustion temperatures that are sought with a view to high efficiency, the exhaust gases should be cooled through a significant temperature range. The lower the cooling rate, the greater the remaining amount of nitrogen oxide. Preferably, the exhaust gases remain in the slow cooling temperature range for at least 0.3 s.

In particular, the cooling rate should in the temperature range

with slow cooling approximate the nitrogen oxide's temperature-dependent decomposition rate, i.e. decrease in this temperature range.

It is also advantageous if the initial temperature of the area with slow cooling is kept at at least 1,400°C. The temperature range with slow cooling is therefore at a relatively high level where it is possible to utilize high cleavage rates.

In the following, the invention will be elucidated in more detail by means of examples of execution which are illustrated in the drawing. Fig. 1 shows a cross-section of several hollow fibers coated with a membrane. Fig. 2 shows a perspective view of an apparatus according to the invention cut through along the line II-II in fig. 3. Fig. 3 shows a horizontal section of the device in fig. 2. Fig. A., shows. longitudinal section of end portions of hollow fibers of modified form in an end wall of the capsule.

Fig. 5 shows a section along the line V-V in fig. 4.

Fig. 6 shows a schematic longitudinal section of a device for the production of hollow fibres. Fig. 7 shows a schematic cross-section of an embodiment of a hollow fiber with an internal membrane. Fig. 8 similarly shows a modified embodiment

for the fiber.

Fig. 9 schematically illustrates the course of a method for producing an internal membrane.

Fig. 10 shows a cross-section of a part of another device

to produce an outer membrane.

Fig. 11 shows a corresponding longitudinal section of this device. Fig. 12 illustrates the equilibrium state air : nitrogen oxide in a diagram of the proportion of nitrogen oxide as a function of the exhaust gas temperature T. Fig. 13 is a diagram of the decomposition half-life tH of the nitrogen oxide as a function of the exhaust gas temperature T. Fig. 14 is a schematic diagram of the course of the exhaust gas temperature as a function of the time during cooling. Fig. 15 schematically shows an internal combustion engine with an apparatus for reducing the proportion of nitrogen oxides in the exhaust gas.

Fig. 16 shows a cross-section of the apparatus along the line XVI-XVI

on fig. 15.

Fig. 17 shows a schematic cross-section of another embodiment of an apparatus for reducing the nitrogen oxide proportion. Fig. 18 shows yet another embodiment of such an apparatus. Fig. 19 shows a fourth embodiment of such an apparatus, and

fig. 20 shows schematically the installation of the device according to the invention in a motor vehicle.

In fig. 1 shows a series of hollow fibers 1 arranged one above the other, which are internally coated with an ultra-thin semipermeable membrane 2. The hollow fibers have e.g. an outer diameter d of 50 to 400 µm, in particular 100 to 200 µm and a wall thickness s which is from less than 6 µm to 20 µm, in particular 5 to 10 µm. The membrane has e.g. a thickness of 100 nm. The cavity 3 of the hollow fibers forms a first space A, and the space outside the hollow fibers forms another space B. If these two spaces are kept at different pressures, the gas migrates from the space with higher to the space with lower pressure, and the membrane 2 is here more permeable to oxygen than for nitrogen.

Fig. 2 and 3 show an apparatus where an extremely high number of the described hollow fibers are used. A battery 4 with length 1 10 cm, height h 20 cm and width b 60 cm can contain 6 million or more hollow fibers 1 which extend parallel to each other in the longitudinal direction and give a membrane area of approx. 180 m 2 or more.

The fiber battery 4 is placed in a capsule 5 with two end walls

6 and 7 where the ends of the hollow fibers 1 are inserted under sealing on their outer circumference. Advantageously, the end walls 6 and 7 consist of synthetic material which glues the circumferential rafts of the fibers together. The first room A thus has in front of the end wall 6 an inlet 8 through which normal air can be led into the inner cavity 3 in the hollow fibers 1.

Behind the end wall 7 is an associated outlet 9 where oxygen-poor air is led away. In front of the inlet 8 is an air filter 10. The entire device can be built into a dashed motor vehicle 11 near its front side 12 with the hollow fibers 1 running in the longitudinal direction of the vehicle so that the speed wind ensures that a sufficient amount of air passes through the hollow fibers. Instead or in addition, there can be a ventilator 13 in the outlet.

In the fiber battery 4, the hollow fibers 1 are arranged in parallel rows 14 with channels 15 between them. These channels open into outlet collector rooms 16 and 17 which are part of the other room B, which is connected via a common outlet 18 to a suction pump 19 whose transport- page 20 leads to a consumer, e.g. an internal combustion engine. The output collection rooms extend over the entire area of the upper

and lower capsule wall, respectively 21 and 22, i.e. over an area 1 x b. In this way, e.g. the total surface of each individual hollow fiber without disturbing resistances in connection with the outlet 18 from the other room B. The width of the channels can be relatively small, as the fibers are also small and the maximum extent in the height direction only amounts to h/2, i.e. 100 mm in the design example .

In the embodiment of fig. 4 and 5, hollow fibers 51, which are coated with membrane 52 on the outside, are provided with sections 53 of larger diameter. These are here at the ends of the hollow fibers and are sealed embedded in an end wall 6. As shown in fig. 5, such hollow fibers in the area of their sections 53 can be arranged closely next to each other, whereby in the rest of the course of the hollow fibers channels 54 are left, which in this case take on a wavy shape.

Such sections 53 can also be arranged at any point along the length of the hollow fibres. They also do not need to lie in a common plane, as already when a section 53 abuts the normal diameter of a neighboring hollow fiber there remains a sufficient channel.

The production of such hollow fibers 51 with section 53 of larger diameter can be done by several precautions which are described in connection with fig. 6. Here there is a spray head 55 which has an annular nozzle for supplying the material 57 for the hollow fibers 51 and a central nozzle 58 through which a gaseous filler is introduced with a pressure p. This pressure p is raised at intervals as indicated by impulses 59. In this way, the extended section 53 arises.

Fig. 7 shows a hollow fiber 1 with internal membrane 2 in cross section. It can be seen that the outer pores 60 are larger than the inner pores 61 which lie just below the membrane 2. While the inner pores e.g. has a size of 15 nm, the pore size increases outward to approx

1 p.m. The pores are interconnected.

In fig. 8 shows another embodiment, where a hollow fiber 62 consists of the same material as the membrane 63. Here, too, the pores 64 become smaller in the direction from outside to inside. However, the innermost pore layer is closed, so the desired membrane 63 appears.

The membrane material must be selected based on consideration of gas permeability and the 02-N2 separation factor. There are various possibilities for this. Silicone rubber (dimethylpolysiloxane) or silicone rubber-polycarbonate copolymer of dimethylpolysiloxane and bisphenol A with a high content (over 80%) of dimethylpolysiloxane are particularly recommended. Silicone rubber has a separation factor between oxygen and nitrogen of -2.2, so the gas mixture in the room with lower pressure has an oxygen content of approx. 30-35 percent by volume. Appropriately, cold-vulcanizable membrane materials are used, and in that connection one should completely or largely forego fillers or pigments so as not to influence the membrane's properties. However, hot-vulcanizable materials also come into consideration.

The cross-linking of the membrane material takes place with the help of a cross-linking component and a catalyst. As a cross-linking component, a wide variety of known materials can be considered for the purpose, preferably ortho- or polysilicic acid esters, alkyltrialkoxysilanes or siloxanes with Si-H bonds. Such crosslinking components can be mixed with the vulcanizable membrane material before the coating, but will also be able to be applied to the peripheral wall of the hollow fibers before the coating. If the hollow fiber material has active groups, such as hydroxyl or alkoxy groups, it will also be possible to waive the use of a crosslinking component.

A wide variety of known materials come into consideration as catalysts. Particularly suitable are organic peroxides, amines or carboxylic acid salts, e.g. tin-II-octoate or dibutyl-tin-dilaurate.

The membrane material can be mixed with the crosslinker component and the catalyst and then dissolved or dispersed after degassing.

A one- to four-percent solution resp. dispersion is recommended. As resolution or dispersants include aromatic or aliphatic hydrocarbons (especially petroleum ether) as well as chlorinated hydrocarbons.

The hollow fibers should consist of a polyaddition or condensation product. Polyester, polyamide, polysulfone, cellulose and cellulose acetate are particularly suitable. Finest reinforcement inlays of other materials are possible.

Fig. 9 schematically illustrates the course of the process when a membrane 2 is applied to the inside of a hollow fiber 1. In a first step 65, the membrane material 67, a catalyst 68 and a cross-linking component 69 are mixed in a container 66. Then the mixture is in a step 70 mixed with a solvent 71. After a certain resting time during which a weak cross-linking can already take place, the solution 72 is introduced in a step 7 3 into the interior of the hollow fibers 1. In a step 74, on the outside at room temperature, a negative pressure -P, whereby the solvent evaporates and is carried away to the outside through the hollow fiber wall. In this connection, the porous wall acts as a filter that allows the solvent to pass, but keeps the membrane material back on the inside • of the hollow fibres. In a step 7 5, heat H is added in a furnace

at approx. 50°C, whereby the remains of solvent are completely removed and the cross-linking is completed accelerated.

This method is simplified by the fact that the hollow fibers 1 are already mounted in the apparatus. For now, the solution can simply be introduced through the inlet 8. There are also no difficulties in bringing the capsule to an elevated temperature. Membranes produced in this way are mechanically protected and are also not influenced by further processing.

In the embodiment of fig. 10 and 11 there are two rollers 76

and 77 each provided with a circumferential groove 78 or 79. The two circumferential grooves are dimensioned so that they provide a passage 8 slightly larger than the cross-section of a hollow fiber 81.

Via a funnel 8 2 , a mixture of flowable membrane material, catalyst and crosslinking component is applied to the overroller 76, which rotates in the direction of the associated arrow. The material reaches the outside of the hollow fibers 81. The passage 80 determines the thickness of the applied layer. The rest is wiped off and can be collected again. The hollow fibers can then be passed through an oven for vulcanization and

then wind up. Instead of the funnel 82, a ring nozzle can also be used to apply the vulcanizable membrane material. The material will also be able to be sprayed on or applied by dipping.

In this way, it is also possible to apply dissolved membrane material.

Yet another possibility consists in the embodiment in fig. 6

to add the membrane material to the filler - with gaseous filler in atomized form and with liquid filler e.g. in resolution.

In the diagram in fig. 12 is the NO share in volume percentage

shown as a function of the exhaust gas temperature T. Curve C separates an area 110 where NO is formed, from an area 111 where NO is split. To the left of the dashed 500° boundary is an area 112 where NO is metastable. It can be seen from this that the proportion of NO in the exhaust gas rises sharply with increasing temperature - and at 2,700°C amounts to approximately 5% by volume.

In fig. 13 shows the curve D the decomposition half-life t„ ri for NO as a function of the exhaust gas temperature T. It can be seen that NO is decomposed practically immediately at 2700 C, in 1/2000 s at 2200°C, in approx. 0.6 s at 1700°C, in several minutes at 1200°C

and during several weeks at 7 00°C.

In fig. 14 the exhaust gas temperature is shown as a function of

the time t. The dashed line marks the exit of the exhaust gas from the combustion engine regardless of scale. In the area below 700°C, practically no NO splitting can be expected anymore. Curve E shows the known case when a combustion took place

at approximately 2,000 to 2,200°C and the exhaust gas exits the internal combustion engine at approx. 1,000°C. In the exhaust bend, a further, impact-like cooling takes place, so the exhaust gas contains a considerable proportion of the NO which was present at a higher temperature.

Curve F shows a cooling process in accordance with the invention at the same conditions in the internal combustion engine. In a first temperature range 113, which here extends from slightly above to slightly below 1,000°C, cooling is slowed. Only in the subsequent temperature range 114 does a sudden cooling occur. The mentioned temperature range 113 is run through during a time of approx. 0.5 s. Since in the first temperature range 113 nitrogen oxides are reduced to a considerable extent and the proportion of nitrogen oxides before the rapid cooling is therefore smaller than in the case of curve E, there is also a smaller proportion of nitrogen oxides in the exhaust gas after the cooling.

The same applies to curve G, which characterizes the case where the combustion as a result of an increased proportion of oxygen in the combustion air takes place at approx. 3,000°C and the exit temperature of the exhaust gas amounts to around 1,700°C. Here, the cooling is carried out slowly in a temperature range 115 which reaches down to 1,300°c and lasts a time of approximately one second. In the following temperature range 116, rapid cooling takes place. In this way, despite the high output values at the output of the internal combustion engine, it is possible to reduce the proportion of nitrogen in the exhaust gas to low values that can be defended. In practice, the dwell times can also be chosen shorter or longer.

In the embodiment of fig. 15 and 16, an internal combustion engine 117 is supplied via a line 118 with combustion air whose oxygen content has been increased in a device 5. The exhaust gas is led away through a channel 120 consisting of a first pipe section 121, a container 122 and a pipe section 123 which leads to a silencer. The pipe section 121 and the container 122 are provided with a thermal insulation 124. In the container is a spiral-shaped wall 125. The exhaust gas, which is supplied in the middle, therefore runs through a spiral-shaped channel 126 from the inside outwards. As a result of the slowed heat release and the relatively long time when the exhaust gas is exposed to these conditions, the desired slow cooling occurs through the first temperature range.

In the embodiment of fig. 17, an exhaust gas channel 127 includes a first pipe section 128, a container 129 and a second pipe section 130, all surrounded by a heat insulation 131. In the container, walls are arranged on both sides of a central chamber 132 which extend alternately from each side , so two labyrinth-shaped exhaust gas channel sections 134 and 135 are obtained. If the flow path in the container 21 is sufficiently long, the external heat insulation can also be dispensed with on the underside of the side walls, since the exhaust gas that flows through the last channel section 136 in the container 129 , acts as thermal insulation for the previous sections.

In the embodiment in fig. 18 shows an apparatus 137 three series-connected containers 138, 139 and 140 mutually connected by throttling sections 141 and 14 2. In this way a silencer function is obtained. The associated thermal insulation is not indicated. From the container 14 0, via a return line 143 with compressor 144, exhaust gas is injected into the container 139 by means of an injection device 14 5. Thanks to the compression in the unit 144, the returned exhaust gas absorbs heat energy. The pressure can be selected so that this exhaust gas is led into the container 139 at a very high speed, especially supersonic speed. Thanks to the collision of molecules, kinetic energy is converted into heat energy, so the exhaust gas in the container 139 is kept longer at a predetermined temperature level.

In the embodiment of fig. 19, a first container 146 is connected to another container 148 via a strong channel narrowing 147. The exhaust gas, which is accelerated in the narrowing 147, hits a baffle plate 149, whereby kinetic energy is again converted into heat energy and the exhaust gas in the container 148 is therefore kept longer on a certain temperature level.

Fig. 20 schematically shows the arrangement of a capsule 5 (Fig. 2

and 3) and a container 110 (Fig. 15) in connection with the internal combustion engine 150 of a motor vehicle 11. Via the line 151, C^-enriched air is supplied to the ordinary carburettor. At 152, the exhaust gases exit the engine after combustion.

In a similar way, a combustion plant can also be operated with a correspondingly high degree of efficiency.

Claims (30)

1. Apparatus for increasing or decreasing the oxygen content of air to be supplied to a consumer, in particular a combustion chamber, using a very thin semipermeable membrane that separates a first chamber, which has a higher pressure and has an inlet for normal air and an outlet for air with a reduced G^ content, and another room, which has a lower pressure and has an outlet for G^ -enriched air, characterized in that hollow fibers (1, 51, 62) with a microporous wall exhibit the membrane (2, 52, 63) on a peripheral surface and are arranged in large numbers and nested parallel to each other in a capsule (5) whose opposite end walls (6, 7) the ends' of the hollow fibers pass through, and these ends are sealed on their outer circumference. 2. Apparatus as stated in claim 1, characterized in that the hollow fibers (1, 51) form a carrier such as the membrane (2, 52) is applied. 3. Apparatus as stated in claim 1 or 2, characterized in that the hollow fibers (62) consist of the membrane material. 4. Apparatus as stated in claim 1, 2 or 3, characterized in that the hollow fibers have reinforcement inserts in their wall. 5. Apparatus as stated in one of claims 1-4, characterized in that the inner cavity (3) of the hollow fibers (1, 51) forms the first space (A) and the capsule space outside the hollow fibers forms the second space (B). 6. Apparatus as stated in one of claims 1-5, characterized in that there are at least 100,000 and preferably more than 0.5 million hollow fibers. 7. Apparatus as specified in one of claims 1-6, characterized in that hollow fibers (1) are arranged parallel to each other in such a number in a hollow fiber battery (4) that a membrane area of 15-500 m 2 appears. 8. Apparatus as stated in one of the claims 1-7, characterized in that the hollow fibers (1) are arranged in a capsule (5), and that at least one output collector space (16, 17) extends along a capsule side wall (21, 22 ) which run parallel to the hollow fibres. 9. Apparatus as set forth in claim 8, characterized in that the capsule (5) has rectangular end walls (6, 7) with a long side and a short side, and that the output collector space (16) extends along a capsule side wall (21) running between the long sides of the end walls and essentially over its entire area. 10. Apparatus as set forth in claim 9, characterized in that another corresponding outlet collector space (17) extends along the opposite capsule side wall (22). 11. Apparatus as stated in one of claims 1-10, characterized in that the hollow fibers have an outer diameter of 100-400 µm, preferably approximately 200 µm. 12. Apparatus as specified in one of claims 1-11/characterized in that the hollow fibers have a wall thickness of no more than 20 pm and preferably less than 6 pm. 13. Apparatus as specified in one of claims 1-12, characterized in that the hollow fibers have a length of less than 200 mm, preferably of approx. 100 mm. 14. Apparatus as specified in one of claims 1-15, characterized in that the pore size of the hollow fibers decreases towards the membrane. 15. Apparatus as stated in claim 14, characterized in that the size of the pores covered by the membrane is 20-50 nm. 16. Apparatus as stated in one of claims 1-15, characterized in that the membrane (2, 63) is arranged on the inner circumference of the hollow fibers (1, 62). 17. Apparatus as stated in one of claims 1-16, characterized in that there is an air filter (10) in front of the entrance (8) to the first room (A). 18. Apparatus as stated in one of claims 1-17, characterized in that the hollow fibers (1) in the case of installation in a power vehicle (11) extend in its longitudinal direction and with one end close to the front of the vehicle (12). 19. Apparatus as stated in one of claims 1-18, characterized by a blower (13) for driving the air through the inner cavity (3) of the hollow fibers (1). 20. Apparatus as specified in one of claims 1-19, characterized in that the combustion chamber is part of a combustion engine (117, 150) or a combustion plant, and that the membrane area is chosen so large that the combustion temperature is above 2,500°C. 21. Apparatus as stated in claim 20, characterized in that a device (122, 129, 125, 147-149) is assigned to the combustion chamber's exhaust gas channel to reduce the proportion of nitrogen oxide. 22. Apparatus as stated in claim 21, characterized in that the exhaust gas channel in its first part exhibits a thermal insulation (124, 131) which causes a retardation of the exhaust gas cooling, promoting the breakdown of nitrogen oxide. 23. Apparatus as stated in claim 21 or 22, characterized in that at least one device (145, 147-149) is assigned to the exhaust gas duct for reaction-free heating of the exhaust gases. 24. Method for producing an apparatus as stated in one of claims 1-23, characterized in that the hollow fibers are first produced and then treated with a coating liquid containing membrane material, after which the membrane material is cross-linked onto the hollow fibers. 25. Method as stated in claim 24, characterized in that the coating liquid contains a dissolving or dispersing agent for the membrane material, and this agent is then removed. 26. Method as stated in claim 24 or 25, characterized in that the hollow fibers are sprayed with the coating liquid. 27. Method as stated in claim 24, 25 or 26, characterized in that the coating liquid is led into the interior of the hollow fibres. 28. Method as set forth in one of claims 24-27, characterized in that a filler containing membrane material is introduced into the fiber material during the production of the hollow fibers in the fiber material to produce the inner cavity. 29. Method for operating an apparatus as specified in one of claims 20-23, characterized in that by enriching the combustion air with oxygen, a combustion temperature of more than 2,500°C is provided in the combustion chamber, and that the cooling of the exhaust gases leaving the combustion chamber, within a temperature range of at least 200°C occurs more slowly than through a subsequent temperature range. 30. Method as stated in claim 29, characterized in that the cooling rate in the temperature range for slow cooling is approximately the nitrogen oxide's temperature-dependent decomposition rate.