DE2727794A1 - Foundry cores hardened by catalyst gas mixed with air - where analysers in gas recovery circuit prevent danger of an explosion - Google Patents

Abstract

The parent patent describes the hardening of foundry moulds, esp. cores made of sand with a resin binder and hardened by a mixt. (ab) of a gas or vapour catalyst (a) in a carrier gas (b). The mixt. (ab) is fed through the core and then collected so cpd. (a) can be sepd. from the mixt., purified and re-used in a closed circuit. In this addn. gas (b) is air; the mixt. (ab) is drawn through the core by suction; and the concn. of cpd. (a) in the mixt. flowing through the circuit is continuously monitored and kept below a critical value (CCa) which could cause an explosion. The suction time is pref. longer than the gassing time to allow air only to be drawn through the core.

Description

Method and device for the catalytic curing of

synthetic resin-bonded sand moldings (addendum to patent 2,350,588) The invention initially relates to a method for the catalytic curing of synthetic resin-bonded Sand moldings according to the preamble of claim 1, in particular according to patent 2 55o 588.

In the previously published main patent, the teaching is given, the catalyst / carrier gas mixture to run the catalyst in a closed circuit during curing isolate the mixture, purify it and recycle it. It it should be remembered here that the most widely used catalyst is one at room temperature liquid, volatile amine, e.g. B. triethylamine is, which is also in very strong dilution has a foul smell, is poisonous and slightly explosive. When the closed Circulation must therefore be very careful that no catalyst vapors can step outside in the area of the molding machine. This creates certain poetry problems at the molding box, which for the purpose of removing the finished sand mold along a running dividing joint must be divided transversely. The ready-mixed loose molding sand is normally filled in a shot into the closed mold by means of compressed air. If the mold is well sealed at the dividing joints, there will be a build-up of air, which a sharp contour filling of the form with molding sand hinders. It also builds up Inside the mold there is a very high air pressure due to the large curses the molding box leads to very high forces. A well sealed from the outside Shape was therefore relatively complicated not only because of the seal, but because of the high pressure forces to be absorbed are also very difficult and accordingly expensive.

The object of the invention is to provide a procedure which it allows simpler and lighter forms to be used.

According to the invention, this object is achieved by the characterizing features solved by claim 1.

The three essential features of the invention, namely air as Carrier gas, application of vacuum to suck through the catalyst and concentration control of the catalyst in the mixture work closely together. Thanks to the use of vacuum the mold no longer needs to be carefully sealed to suck the catalyst through due to the fact that the catalytic converter can no longer enter the open air at leakage points, On the contrary, gas is injected from outside at these points. thanks to the use of air as the carrier gas is this Sniffing air easily tolerated in the system.

But since the catalyst forms an explosive mixture with air, must be due appropriate monitoring, the concentration on non-critical values outside of the explosion area.

It was possible to develop analyzers that measure the concentration of catalytically active amines in oxygen or in air in a reliable manner allow.

Appropriately, you will train these devices in this way and at the Arrange measuring point so that they offer a high level of reliability, because of the reliability the concentration measurement, the operational safety of the system with regard to the risk of explosion depends. It is expedient to use a parallel multiple arrangement of sensitive Provide elements at a measuring point and constantly compare the measurement results of the various sensitive elements. In the event of a deviation in the measurement result one of the sensitive elements from the results of the remaining elements becomes one Self-monitoring device give a signal to the outside for control or for maintenance of the measuring arrangement. Also constantly repeated control measurements on one Calibration mixtures are conceivable.

By suitable mutual measurement of the suction time compared to During the gassing period, the catalyst can certainly escape despite the leaky form be avoided. Due to a longer dimensioning of the suction line also over time after opening the mold, the sand mold body can be flushed with air, so that it can no longer evaporate any catalyst even after removal from the mold.

The amount of catalyst required depends on the size of the sand molding and on the type and amount of resin contained therein. Because the working cycle is operated with a defined catalyst concentration, the amount of catalyst can be set by a corresponding gassing time. This opens up the possibility of a working cycle for the catalyst preparation centrally for several core shooters to provide; Every single core shooter no longer needs a separate one To be assigned to metering device.

If for any reason the concentration of the catalyst ii With regard to the risk of explosion grow into critical concentration values, in this way, the concentration monitoring can automatically initiate measures that lower the concentration back to uncritical values. As emergency measures First, an alarm signal to the operating team or a blockage come of the working cycle immediately behind the mold and blowing off the mixture into the open air in question. Can be used to lower the concentration in the working circuit Dilution air can be sucked into this and / or it can be a chemical catalyst be converted into a harmless form, e.g. B. by carbonizing the catalyst by means of carbon dioxide and water.

In the case of the low concentrations to be maintained, sufficient is sufficient Supply of water the natural humidity in the environment at all times. From the carbonate, the catalyst can be replaced by a stronger lye, e.g. B. soda, against being released. Through the chemical bonding and excretion of the catalyst the cleaning cycle is partially relieved from the mixture. The isolation of Catalyst from the mixture can also be completely based on chemical Ways are done so that a physical isolation of the catalyst is completely dispensable can be. To this extent, this idea is also detached from the present invention or from the one according to the main patent applicable as it is also applicable to inert carrier gases or even completely without physical condensation of the catalyst from the mixture is applicable.

To relieve the work cycle of unnecessary dirt and moisture the shot air is preferably blown into the open during the filling of the mold.

The reaction rates in catalytic curing and in the event of failure of the catalytic converter in the event of danger, this can accelerate that the catalyst / air mixture is heated on the inlet side to the mold. This warming up can be achieved by utilizing the compression heat of the compressor. One A constant high temperature can be achieved by mixing in cold air from one point be maintained behind the cold trap.

To practice the method, the invention is based on one of the main patent known device for the catalytic curing of synthetic resin-bonded sand molds from, as described in more detail in the preamble of claim 20.

In terms of apparatus, the invention is based on the object to design the device in such a way that despite the application of the return principle for the catalyst and despite strict avoidance of catalyst leakage at any one Place the molding box in a lighter, air-permeable place, especially on the mold itself Construction can be created.

According to the invention, this object is achieved by the characterizing features solved by claim 20.

The combination features mentioned there act within the meaning of the invention together in such a way that the catalyst mixture is sucked through the sand molding is that air to prevent a catalyst leakage and to rinse the sand molding sucked into the circuit from the outside through leaks in the form and that the concentration of catalyst increases above a critical threshold addition is avoided.

The invention is based on an embodiment shown in the drawing briefly explained below.

The figure shows a process scheme as an exemplary embodiment for a Device according to the invention and for performing an exemplary method according to the invention.

In a cleaning circuit 13 are - starting on the low pressure side the main or supply line 6 - a low-pressure tank 1, a compressor 2, a heat exchanger 3 with a cooling unit 4 and a high-pressure container 5 are arranged. Both containers are connected via a return line 7 * in which a relief valve 8 is arranged, which can be controlled by a low pressure monitor 9. On the high pressure tank 5 a pressure relief valve 11 is arranged, which can be controlled by the high pressure monitor 1o is. The refrigeration unit is v-connected to the heat exchanger 3 via a valve, which can be controlled via a temperature monitor 12 and via which an approximately constant low temperature can be maintained on the high pressure side of the circuit can The pressure relief valve 11 and the high pressure monitor 10 have the task of controlling the pressure level on the high pressure side at an optimal height for the process sequence and excess carrier gas, which is constantly sniffing at the molding boxes will be released into the open. On the low pressure side, the pressure level is determined by means of of the Vontile 8 and the low pressure switch 9 kept constant. The pressure height on the low pressure side is well below the ambient air pressure, so that of the Low-pressure side of the circuit 13 can be performed from a suction work.

The mode of operation of the cleaning cycle is already in the main patent described; Let it be repeated here briefly: In the one in the cleaning cycle circulating mixture of essentially air and catalyst is located Catalyst component of the mixture near its evaporation point. To the cold surfaces of the heat exchanger 3, the temperature drops below the dew point the catalyst component of the mixture; the catalyst condenses and separates in liquid form and gets into the high-pressure container 3. Due to the expansion of the compressed and catalyst-depleted mixture at valve 8 occurs by using the well-known Joule-Thomson effect for further cooling of the mixture. Due to a serous circulation, the catalyst component is constantly of the mixture excreted in liquid rorn at the cold trap. It'll get through the cold trap and the mixture cooled by the Joule-Thomson effect due to the largely adiabatic compression reheated - this compression heat is exploited in the working cycle- To the cleaning circuit 13 is a working circuit 26 is connected. Him the aforementioned heat of compression of the Gerish To be able to use it for the working cycle, the working cycle is immediate connected behind the compressor 2 with its branch line 20. The heat of compression benefits the working cycle in several ways. On the one hand, the pre-nebulized As a result, the catalyst can be completely gasified and the mixture is homogenized, on the other hand The catalytic curing can be accelerated by increasing the temperature in this way finally, in case of danger, the catalyst can be carbonized by means of Carbon dioxide and water are also accelerated.

In the working circuit 26 are in addition to the compressor 2 and the low-pressure tank 1 a mixing chamber 21, several core shooters 22a, b, each with a molding box 23a, b and in the return line 24 a dust filter 25 is arranged.

To control the process are in or on the work cycle the following details are also provided; In the branch line 20 is a feed of cold air via the temperature control valve 14 from the recooled high pressure side the cleaning circuit provided; by means of the arranged at the feed point Cold air can be fed into the working circuit 26 in a targeted manner to a defined constant high temperature in the flow of the working cycle to get.

A metering valve 28 for catalyst mist is provided in front of the mixing chamber, which can be led from the catalyst tank 43 zugeder catalyst, in which / by means of dry and inert behavior via the nebulization valve 44 carbon dioxide gas blown in from the storage container 38 can be pre-misted. An analysis device 27 is arranged behind the mixing chamber in the flow direction. With the help of this analyzer, the concentration of catalyst within of the mixture determined and controlled by the metering valve 28 and the nebulization valve 44 can be kept at a consistently high, uncritical value. Parallel to Mixing chamber as well as to the dosing point and to the analysis point is a circulation pump 29 arranged, which for a constant flow of mixture within the metering, Mixing and analysis section ensures, even if the mixture is within the branch line 20 should stagnate at the moment. Because of this forced promotion, overdoses can occur to be avoided on catalyst.

By adding catalyst mist to the working cycle Any residual water carried along due to carbonization of the catalytic converter chemically bound and dried in this way the mixture of the working cycle. Of the Karionized catalyst is harmless with regard to the risk of explosion; he will not even registered at the analysis center. The exit of the mixing point within the branch line 20, an always consistently highly enriched with catalyst dry mixture that is uncritical with regard to the risk of explosion, which has a Ring line several core shooters can be supplied for processing.

Within each of the core shooters 22a, b is a molding box 23a, b, which can be opened via a dividing joint 19. The molding box is designed in a lightweight design with an unsealed dividing joint, so that Ambient air can be sucked in at the dividing joint 19 (flow arrow 39). In front of each molding box there is an inlet valve 30 and behind it an outlet valve 31 arranged. Both valves are separated in time via a zoom control device 32 controllable. The opening times for the valves can be adjusted so that both valves open approximately at the same time - possibly even an earlier one can open Opening the drain valve to evacuate the mold would be cheaper - but that on In any case, the drain valve closes much later than the inlet valve the sand molding of the air / catalyst mixture contained therein by suction to be able to flush with ambient air. The time control unit 32 for the valves can can be controlled by the control unit 34 of the entire core shooting machine.

A blow-off valve branches off between the molding box and the drain valve 31 33, which can also be controlled by the control unit 34 of the core shooting machine is. This valve is during the shot-like filling of the molding box with molding sand open for a short time to the booty air and contaminants brought in with it To be able to blow off into the open and to be able to keep away from the work cycle, what is permissible because this air is free of catalytic converters.

All core shooters are connected to a return line 24 within of the working circuit 26 connected. In this return line is located another analyzer 35, which is the catalyst concentration monitored in the return of the working cycle and by means of concentration-reducing Keeps measures within a non-critical area. When concentration becomes critical can be an acoustic or an optical signal to the outside via the signaling device 40 Signal to warn the operator. Furthermore, via the Carbonation valve 36, which opens into the return line 24, carbon dioxide fed into the return. The initially dry mixture within the The working cycle has changed on the core shooters due to sand moisture and enriched with water by humidity from the purge air. This moisture and the additional carbon dioxide cause carbonization of at least one Part of the catalyst, so that the concentration is reduced to uncritical values can be. A control unit 37 can also be activated by the analysis device 33 are, in turn, the drain valves 31 regardless of any other opening pulses constantly blocked and the relief valves cyclically according to the flushing time or also keeps constantly open, so that the working mixture is no longer in the return line 24 of the Can reach the working cycle, but - in the present threatening dangerous situation - is blown out into the open. The corresponding lines of these relief valves are preferably up to the hall roof directly into the open air, we that escaping mixture with the ambient air to uncritical concentration values can dilute.

Before entry of the working circuit return into the low-pressure tank 1 a pressure control valve 48 is also arranged, with which the pressure level within the return line 24 can be controlled via the pressure switch 49.

The mode of operation of the working circuit 26 is now briefly as follows: In the branch line 20, the mixture is dry and constant high uncritical concentration and in one above atmospheric pressure Pressure on. The pressure in the return line 24 is always below atmospheric pressure there is negative pressure. At a core shot inside a core shooter the three valves 30, 31 and 33 are controlled by the control unit 34 and the timing unit 32 controlled. The shot air is released through the initially briefly opened relief valve 33 blow into the open. After the mold is filled, the both valves 30 and 31 open, the relief valve 33 being closed. To a time sufficient for the hardening of the sand molding body in which sufficient Catalyst could flow in, the inlet valve 30 is closed, whereas the The drain valve is still kept open due to the in the return line 24 Pending negative pressure is now about shape imperfections in the ambient air The molding box is sucked in and through the sand mold and the sand mold flushed of adhering catalyst mixture. The extracted with purging air diluted and due to the addition of atmospheric moisture with regard to the proportion of catalyst partially carbonized mixture reaches the return line due to the pressure gradient and through the dust filter 23 into the low-pressure container 1 and thus into the cleaning circuit 13 back. Dust that has been entrained can be separated from the mixture at the dust filter 23 will.

When the used working mixture enters the cleaning cycle this mixes with the Gemisoh of the cleaning cycle. The hourly Circulating quantities in the cleaning circuit are greater than the corresponding circulating quantities in the working cycle; there are also - at least on the low pressure side - the concentrations of catalyst in the cleaning cycle is significantly lower than in the working cycle. Thanks to these proportions and concentration ratios, it comes through the feed of the used working mixture in the cleaning cycle only to one slight increase in dirt and catalyst concentration in the cleaning circuit; overall, however, is in the state of equilibrium after the working mixture has been fed in in the cleaning cycle, however, a relatively clean one and in terms of catalyst and dirt low-concentration air before that - immediately after compression - can be returned to the working cycle as a carrier gas. Since the Concentration of catalyst in the cleaning circuit due to the ongoing removal of the catalyst - as I said - is significantly lower than in the working cycle, it is also sufficient the catalyst concentration in the system only in the working cycle * d. H., monitor where the higher concentrations occur. As long as there the concentrations are not critical, they are definitely also in the cleaning cycle. Also the Circulating moisture in the circuits is due to the constant discharge @ on Consolidated water in the cleaning circuit is lower than in the working circuit and is automatically at permissible and in the steady state in both cycles easily controllable values.

In case of danger, d. H. in the event of a critical increase in the catalyst concentration At the analysis point 35, carbon dioxide gas can be emitted via the carbonation valve 36 the container 38 are fed into the return line, so that the catalyst converted into a largely harmless carbonate and the concentration of catalyst can be depressed. Should be contained in the mixture in the return line 24 If moisture is not sufficient for carbinization, 5o a humidification 51 of the supplied carbon dioxide gas can be provided.

In addition to the cleaning circuit 13 for the mixture and the working circuit 26 is still another circuit for cleaning the catalyst in the process sequence intended.

This purification is carried out by distillation in the de-distillation column 41, which is connected to the high pressure container 5. To release the catalyst from the carbonate - this is also eliminated in the cleaning circuit 13, collects in the high pressure vessel 5 and reaches the distillation column 41 - a stronger lye than the carbonate, namely in the example, is used in the cleaning template Sodium hydroxide solution, supplied from the container 45 via the metering pump 46. The lye supply can be dosed in a targeted manner by means of the alkalinity measurement 47. The caustic soda sets from the carbonate the catalyst in freedom and forms a carbonate (sodium bicarbonate) itself, which can be drawn off on one of the distillation trays of the column 41 Purified catalyst can be drawn off and transferred to another intermediate floor Return pump are fed into the pressurized catalyst container 43. In the column itself, the atmosphere contained therein consists of the vapors of the liquid mixture withdrawn from the container 5 and contains no air, so that here too there is no risk of an explosive gas mixture being produced is. L e r s e i t e

Claims (1)

Claims 1. A method for curing sand moldings, in particular Casting cores, made of synthetic resin-bonded sand using gaseous or vaporous Catalyst which is added to a carrier gas, followed by the catalyst / carrier gas mixture conveyed through the mold which holds the loose sand mold body, which is drawn from the The gas mixture escaping from the form is collected as completely as possible and for use of the catalyst contained is recirculated in the circuit, the catalyst is isolated from the mixture, cleaned and reused, especially after Patent 2,550,588, d u r c h e k e n n n e i c h n e t, that as a carrier gas Ambient air used, the concentration of catalyst in the mixture within the Circuit (26) continuously monitored at at least one point and below one critical concentration value for the risk of explosion and that the catalyst / air mixture is sucked through the sand molding. 2. Ancestors according to claim 1, d a d u r c h g k n n -z e i c h n e t that the suction time is longer than the Inflow time of mixture - gassing - and during the pure suction time - rinsing - Ambient air (39) through leaks in the mold (19) through the sand molding is sucked into the circuit (26). 3. The method according to claim 1 or 2, d a d u r c h g e -k e n n z e i c h n e t that in a circuit passed through the mold (23a, b) - Working circuit (26) - catalyst is continuously metered in such that uninterrupted in the working circuit (26) at least at the admixing point (21) there is always a catalyst / air mixture of a defined, non-critical concentration. 4. The method of claim 1, 2 or 3, d a d u r c h g e -k e n n notices that when a critical concentration threshold is exceeded Blow the catalyst / air mixture emerging from the mold (23+, b) into the open will. 5. The method according to any one of claims 1 to 4, d a d u r c h g e k It is noted that when a critical concentration threshold is exceeded additional air is sucked into the circuit (26). 6. The method according to claim 5, d a d u r c h g e k e n n -z e i c h n e t that drawing in additional air, at least in part, by expansion the flushing time is effected. 7. The method according to any one of claims 2 to 6, d a d u r c h g e k It is noted that at least after fumigation1, preferably for a short time the sand molding is also rinsed or slightly evacuated beforehand. 8. The method according to any one of claims 2 to 7, d a d u r c h g e it is not indicated that rinsing takes place until the mold is opened (23a, b) is maintained. 9. The method according to any one of claims 1 to 8, d a d u r c h g e it is not noted that the catalyst - preferably reversible - is chemically bound will. lo. Method according to claim 9, d a d u r c h g e k e n n -z e i c hn e t that the catalyst is carbonated by means of carbon dioxide and water and in this form is precipitated. 11. Vorfahron according to claim to, d a d u r c h g e k e n n z e i c It does not mean that the water contained in the ambient air sucked in during flushing Humidity is used. 12. The method according to claim lo or 11, d a d u r c h g e k e n n shows that the catalyst is made from the carbonate by means of a stronger lye, z. B. sodium hydroxide solution, released again, the released catalyst cleaned, preferably is purified by distillation and reused. 13. The method according to any one of claims 1 to 12, d a d u r c h e e it is not noted that the entire catalyst is removed from the Catalyst / air mixture reversibly chemically bound by chemical release isolated, cleaned and reused. 14. The method according to any one of claims 1 to 13, d a d u r c h g e it is not indicated that the catalyst / air mixture circulated in the working circuit (26) is dried prior to the addition of catalyst. 15. The method according to claim 14, d a d u r c h g e k e n n -z e i c It should be noted that drying can be reduced by mixing in a catalyst / air mixture Concentration with dry air and cleaned catalyst from a cleaning circuit (13) takes place in the working circuit (26). 16. The method according to any one of claims 1 to 15, d a d u r c h g e it is not indicated that the mold (23a, b) during the weft-like filling is vented to the outside with molding sand. 17. The method according to any one of claims 1 to 16, d a d u r c h g e it is not indicated that the temperature in the working circuit (26) is opposite Ambient temperature is raised. 18. The method according to claim 17, d a d u r c h g e k e n n -z e i c It should be noted that the temperature increase is caused by compression of the air. 19. The method according to claim 17 or 18, d a d u r c h g e -k e n n indicate that the temperature is by mixing in cold air, preferably of circulation air that has passed through a cold trap (3) in the cleaning circuit (13), is controlled on a certain vert 20. Establishment for Hardening of sand moldings, in particular of cast cores made of synthetic resin bonded Sand by means of a gaseous or vaporous catalyst, with a through a the Closed mold containing sand moldings, also with a continuously operating cleaning circuit for the catalyst / carrier gas mixture, which cleaning circuit consists of a low pressure tank, a compressor, a preferably designed as a cold trap catalyst separator, a high-pressure container and a throttle or relief valve or the like. formed between the pressure vessels is which two circuits are intermeshed with one another in such a way that at least the compressor and the low-pressure tank are common to both circuits, in particular according to patent 2 55o 388, for practicing the method according to claims 1 to 19, g e k e n n -z e i c h n e t d u r c h the combination of the following features: a) the Cleaning circuit (13), in particular the compressor (2) and the expansion valve (8) are designed in such a way that the pressure on the low-pressure side (1) is below dos is at atmospheric pressure; b) within the working circuit (26) is both On the inlet side as well as on the outlet side with regard to the shape (23a, b) one each separately controllable valve (30 and 31) or the like. Arranged; c) the shape (23a, b) is designed in such a way that it is at least in the closed state is permeable to ambient air (39) at the dividing joint (19); d) the valves or the like (30 and 31) are in operative connection with a time control device (32), such that the outlet-side valve (31) takes longer with each curing process is switched on than the inlet side (30); e) at at least one point of the Working circuit (26) is a device (33) for the ongoing concentration measurement of Catalyst arranged in the mixture; f) the concentration measuring device (33) stands with a control unit (37) in operative connection in such a way that when the actual concentration is approached to a set concentration value that is critical with regard to the risk of explosion (Critical deterioration of the concentration) automatic concentration-reducing measures would be initiated. 21. Device according to claim 20, d a d u r c h g e -k e n n z e i c h n e t that in the working circuit (26) on the outlet side with respect to the shape (23a, b) a controllable feed valve (36), which with a container (38) for with the Catalyst at least partially chemically reacting agent, especially for carbon dioxide is connected, is arranged, which can be controlled by the concentration control device (33) and is opened when the concentration becomes critical. 22. Device according to claim 20 or 21, d a d u r c h g e k o n n z e i c h n e t that on the working circuit (26) on the outlet side with respect to the shape (23a, b) before the mixture valve (31) on the outlet side there is an opening into the open air controllable blow-off valve (33) is arranged, which of the concentration control device (35, 37) can be controlled and, when the concentration becomes critical, clockwise at Gassing the mold (23a, b) is opened and that the outlet-side mixture valve (31) also in operative connection with the concentration control device (35, 77) stands in such a way that if the concentration is critical, other opening signals be played over and this valve (31) - as long as the over increased concentration lasts - kept closed at all times. 23. Setup according to responses 20 to 22, d a d u r c h g e k It is noted that the concentration control device (35) with an optical and / or acoustic alarm device (40) is in operative connection in such a way that when If the concentration becomes critical, an alarm signal is given. 24. Device according to claims 20 to 23, d a d u r c h g e k It is noted that in the working crisis (26) on the inflow side with regard to the shape (23a, b) a mixing chamber, mixing section or the like (21) for continuous admixing of preferably pre-gasified or pre-nebulized catalyst and behind the mixing chamber (21) another Concentration measuring device (27) is arranged, which with a controllable valve (28) arranged in the Katalyeatorzufuhr in the manner is in operative connection that after the mixing chamber (21) an always constant there is a high non-critical catalyst concentration in the working circuit (26). 25. Device according to claims 20 to 24, d a d u r c h g e k It is noted that one working cycle (26) has the forms (23a, b) of several Molding and curing machines (22a, b) are assigned. 26. Device according to claims 20 to 25, d a d u r c h g e k It is noted that the blow-off valve (33) with the timing control (34) the molding machine (22a, b) is in operative connection in such a way that it is cyclically during the shot-like filling of the mold (23a, b) with molding sand is open. 27. Device according to claims 20 to 26, d a d u r c h g e k It is noted that the working circuit (26) is different from the cleaning circuit (13) branches off on the high-pressure side immediately behind the compressor (2). 28. Device according to claims 20 to 27, d r d u r c h g e k It is noted that the mixture from the cleaning circuit (13) from one point behind the cold trap (3) via a controllable control valve (14) into the working circuit (26) on the inlet side with respect to the shape (23a, b) is feedable, that behind the feed point a temperature measuring point connected to a control device (t5) is arranged and that the control valve (14) with the temperature control device (13) is in operative connection in such a way that the temperature of the mixture at the measuring point is kept consistently high. 29. Device according to claims 20 to 28 with a distillation column for the purification of the catalyst by distillation n e t that an addition of lye, in particular sodium hydroxide solution, is provided at the inlet is. 30. Device according to claim 24, d a d u r c h g e -k e n n z e i c h n e t that in the area of the mixing chamber, the mixing section or the like (21) one at the same time the feed point for the catalyst and the analysis point capturing the mixture even if the mixture stagnates in the supply branch (20) of the working circuit (26) Constantly homogenizing compulsory mixer, circulation pump or similar in the mixing section Like. (29) is arranged.