DE9013241U1 - Drying equipment in cleaning plants - Google Patents

Description

Drying facility in cleaning plants. The invention ^relates to a drying device, in particular

for manually machined workpieces such as turned and machined parts (washing goods) in cleaning or drying plants, with a cleaning fluid circuit, in which there is at least one washing container designed to build up a vacuum for drying, with a cleaning chamber which can be connected to at least one vacuum pump, with a wash goods carrier which can be moved by means of a rotary or rocking drive.

Such a device is known from DE-PS 37 15 168. There, solutions are pumped using a jet pump as a vacuum pump. medium vapours and residual liquids from the cleaning chamber Already by using the jet pump, the

The required drying times can be reduced considerably. The \ Propellant is cooled in the propellant reservoir.

Both solvents and water can be used as propellants.

In another device of this type (US-PS 3,610,260) the cleaning chamber is only sealed against the escape of solvent vapors. The laundry transported from the cleaning chamber is dried by means of a heating device in a separate drying room. The resulting vapors are extracted by means of a pump under slight negative pressure in order to recover the solvent evaporated by the effect of the heating device. A ^satisfactory drying process without a heating device is not possible. In addition,

Heating requires additional energy. Drying under vacuum is not possible in the drying room due to its design.

Another known device of this type (US-PS 44 24 633) has ^a chamber which is openly connected to a solvent evaporator in which the ash is cleaned by means of solvent vapors coming from the solvent evaporator and the condensation heat generated is used to dry the washed material. The contaminated solvents flow away in liquid form, while the gaseous part is sucked away. However, the vacuum pump used for suction is not able to build up high negative pressures for drying, since the cleaning chamber cannot be closed off sufficiently and separated from the rest of the system. In addition, the vacuum pump directs the vapors ultimately sucked away unhindered into the atmosphere.

In a known comparable device (DE-OS 33 19 094) a mechanical pump or a jet pump is used to extract solvent vapors from a pre-chamber upstream of the cleaning chamber. However, this device is not used for drying, but exclusively for reducing the vapors escaping into the atmosphere and for their recovery.

Based on this, the invention is based on the object of developing a device according to the preamble of claim 1 in such a way that the laundry can be dried more quickly and intensively and that, in the case of the use of organic solvents, the burden on the work areas and the environment is thereby considerably minimized. When using aqueous cleaning liquids, the drying process should be ^{significantly} accelerated when a higher degree of dryness is achieved.

This task is solved by the fact that ¹ ^ the washing container can be suddenly connected to a vacuum storage tank during drying.

With such a design ^, the drying times normally required are significantly reduced. This advantage is most effective when, after cleaning the laundry, a vacuum reservoir, which at this point has stored an almost complete vacuum, is suddenly connected to the washing container. The pressure in both spaces, atmospheric pressure in the washing container and almost vacuum in the vacuum reservoir, immediately equalizes. Apart from the fact that the remaining vacuum can now be built up more quickly due to the vacuum in the vacuum reservoir, ^there is also ^the effect that a strong flow occurs in the direction of the vacuum reservoir. With this sudden vacuum shock, drying is effectively supported by the fact that forces are ^suddenly released which tear out any remaining cleaning liquid even from areas of the laundry that are difficult to access and which are higher than the adhesive forces which try to hold a film on the laundry. On the other hand, the sudden pressure equalization through the expansion of the gas mixture in the washing tank causes work to be carried out against the molecular forces of attraction. However, this process is so sudden that no energy can be supplied from outside to compensate for it. As a result, the overall temperature drops, so that the solvent vapors present condense on the way to the vacuum storage tank or vacuum pump.

Because the vacuum pump can build up the vacuum during the washing phase according to claim 6, energy can also be saved, since the pump is operated continuously and no long start-up times are required to build up the vacuum.

If, according to claim 9, a jet pump is used as a vacuum pump, previously unattainable negative pressures and drying intensities can be achieved, at least in large systems, if the overall system is designed to be sufficiently sealed. Due to its simple design without moving parts that can be attacked by aggressive solvents and are subject to increased

Since the jet pump and the associated circulation pump are exposed to wear and tear, the combination of jet pump and associated circulation pump is considerably more wear-resistant than a conventional vacuum pump. In this respect, it is also harmless if the jet pump is kept in operation almost continuously. The circulation pump required to operate the jet pump, on the other hand, can be built in any way, since it is not exposed to a vacuum. This design also has the advantage that the extracted vapors condense to a large extent in the jet pump when they come into contact with the propellants cooled in the propellant storage container, where they come into contact with the inflowing propellant cooled to near the solidification point. Here too ^, the cooling effect described above is noticeable with the sudden expansion of the washing container volume, since the earlier condensation means that less energy is now required to cool the propellant. In addition, tests at the manufacturer's plant have shown that the performance of the jet pump can be increased when the propellant is cooled.

With a design according to claims 13 to 15, the washed parts retained in the strainer basket insert can also be subjected to the drying process. This can reduce the solvent concentrations in the workplace and the solvent residues that enter the environment, especially before the strainer basket insert is removed. This means that the residues that enter the environment * are significantly reduced in places that are not covered by the Federal Immission Control Ordinance or the MAK values, namely in the washed laundry as bulk material and when the strainer basket insert is removed. I

Not shown in the drawing is the further possibility of connecting the filter housing in the machine to the vacuum pump before changing the filter. This option also significantly reduces environmental pollution.

The invention is explained below with reference to an embodiment and the drawing.

The only figure shows the schematically illustrated device.

The objects to be dried, eg mechanically processed workpieces such as turned and stamped parts , are referred to below as washing ^containers . In the cleaning agent circuit of the cleaning and/or degreasing system there is a storage container (not shown in the drawing) for the cleaning agent and a washing container 11. Furthermore, as a rule, there are filters, in particular fine filters for collecting solid particles and often also a distillation system for regenerating the cleaning liquid. The cleaning liquid circuit is driven by means of a circulation pump (not shown in the drawing). A spray pipe 48 is arranged in the washing container 11, which can be tightly closed with a lid 11a and hermetically sealed against the atmosphere and the cleaning liquid circuit, is designed to build up a vacuum and comprises a cleaning chamber 10. Its nozzles open out over a laundry basket 16 which can be moved by means of a rotary or rocking drive 12 and in which the laundry is held. The laundry basket 16 forms a structural unit with the lid 11a and the rotary or rocking drive 12 which can be lifted off the washing container 11 forming the cleaning chamber 10 or placed on this washing container 11. The washing container 11 is connected via a shut-off valve 14 to a collecting container 15 which is also designed to create a vacuum. A strainer basket insert 24 is arranged in the collecting container 15 in such a way that the cleaning liquid flowing from the cleaning chamber 10 into the collecting container 15 flows from above into the strainer basket insert 24, where the majority of the solid dirt particles are caught. Level monitors 25, 25a in the collecting container 15 prevent both overfilling and accidental emptying of the collecting container. The branches of the circuit arranged below the collecting container 15 lead to a cleaning fluid tank (not shown in the drawing) and enable the cleaning circuit to be emptied or filled. The cleaning chamber 10 is connected to the storage tank for the

The air can be drawn from a heat source 55 to heat the supply air via a heat exchanger 54. A branch line 47a connects the ventilation line 47 to the collecting container 15. The collecting container 15 can also be supplied with heated air as required when the valve 52a is closed and the valve 52 is open. The strainer ^basket insert 44 in the collecting container 15 can be moved horizontally (to the left in the drawing) and can be moved out of the collecting container 15 vertically via an opening which can be closed using the cover 15a.

In the embodiment shown in the drawing, a jet pump 34 is used as the vacuum pump. The closable cleaning chamber 10 is connected to the suction port of the jet pump 34 via a suction line 51 with a shut-off valve 56 and to the vacuum reservoir 70 via a three-way valve 72. The vacuum reservoir 70 has a drain valve 71 for draining sediment. For use as a vacuum still, the vacuum reservoir 70 has a filling line 73 with a filling valve 74. The vacuum reservoir 70 can be ventilated or connected to or separated from the jet pump 34 via the three-way valve 72.

The jet pump is located in a propellant circuit and is fed from a propellant reservoir 32 via a propellant line 50 with the aid of a circulation pump 33. A cooling device 35, 37 is provided for cooling the propellant 13' in the propellant reservoir 32. This enables the propellant to be cooled to near its solidification point, which is approximately minus 20 ^° C when using tetrachloroethylene as a chlorinated hydrocarbon and a maximum of 2°C when using water. In the exemplary embodiment, a refrigeration unit 35 operating according to the compression process is used as the cooling device 35, 37. The compressor of the refrigeration unit 35 is located outside the propellant reservoir 32.

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storage tank 32, as can be seen from the drawing. The closed propellant storage tank 32 can be connected to the atmosphere via a vent line 36. It is also connected to the collecting tank 15 arranged at a low level via a condensate return line 45. The suction power of the jet pump 34 can be controlled using a throttle valve 41 provided in the propellant circuit. When the propellant circuit is circulating, the propellant storage tank 32, which is provided with a level monitor 25, 25a, is at approximately atmospheric pressure. When solvents are used, the solvent used as the cleaning fluid is generally used as the propellant. When water mixed with detergents is used as the cleaning fluid, water is used as the propellant.

The facility works as follows:

When the cleaning and/or degreasing system is in operation, phases alternate in which the laundry items fed into the cleaning chamber 10 using the laundry basket 16 are washed or degreased and then dried. In the washing phase, the cleaning liquid passes from the storage container of the cleaning liquid circuit via the line 46 to the spray pipe 48 of the washing chamber 10. This rinses the laundry items in the laundry basket 16 with cleaning liquid, filling the closed cleaning chamber 10. This causes the laundry items to fall below the rising liquid level in the washing container 11. The washing process is supported by the rotary or rocking drive in the washing chamber. As soon as the liquid level reaches the level monitor 11b, the supply of further cleaning agent is stopped. When the washing chamber is flooded as described, the displaced air can escape via the vent line 47 with the vent valve 44 open, without solvent vapors entering the atmosphere. After the washing phase has been completed, the cleaning liquid 13 is emptied into the collecting tank 15 via the open shut-off valve 14. During the washing phase, the vacuum dam 70 is above the

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Three-way valve 72 with the jet pump 34 or another vacuum

or jet pump to create a vacuum. At the beginning During the subsequent drying phase, the closed,

Cleaning fluid 13 emptied cleaning chamber 10 at

opened three-way valve 72 by opening the valve 56 abruptly heated in conjunction with the vacuum of the vacuum storage tank. results - assuming equal volumes v

Cleaning chamber 10 and vacuum reservoir 70 - as a result of pressure equalization, a vacuum half as strong as at the beginning.

un« ■nc^en Voidmin ³ calculates the vacuum to be achieved... _c *;de accordingly. After pressure equalization, the vacuum reservoir 70 about the Dreiwsgevs; 1 72 from the vacuum pump and the

^Cleaning chamber 10 is separated. From there on, the cleaning chamber

10 via the suction line 51 with the jet pump 34 to achieve of a maximum possible vacuum. The

Propellant circuit is activated when the refrigeration unit is running

This creates an intensive flow of air in the suction line 51,

Steaming the cleaning liquid saturated gas stream from the Washing chamber 10 to the jet pump 34, where this gas flow is

which has been cooled down to near the solidification point ■*

Propellant 13' hits. By constantly introducing the condensate into |

the propellant reservoir 32, the propellant level rises to f to a level determined by the condensate return 45. In addition, the propellant level in the propellant reservoir 32 of ·;

Monitored by level switches 42,42a.

After a certain time, the drying result can no longer be improved by applying a vacuum alone. Therefore, when a preset vacuum is reached, a valve 52a can be provided, through which an empirically determined amount of air is fed via a throttle valve 53 to the cleaning chamber 10 via the ventilation line 49. The supplied air can be heated if necessary by a heat source 55 via a heat exchanger 54. By feeding this air into the cleaning chamber 10, further liquid is absorbed, since the relative humidity in the cleaning chamber 10 drops. During this time, the air is fed into the cleaning chamber 10 via a heat exchanger 54.

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The preset negative pressure is maintained at all times. After a predefined period of time has elapsed, the valve 52a closes and the pressure in the cleaning chamber 10 is reduced via the valve 43.

The sieve insert £4 arranged in the collecting container 35 must also be emptied from time to time, as must a filter container not shown in the drawing. In order to prevent solvent residues from escaping into the air of the work area or into the environment, the filter and sieve ends are also dried. To do this, the collecting container 15 can be drained of the

Liquid 13 can be placed under vacuum with valve 52a closed and valve 52 ^open . If necessary, heated air can be supplied with valve 52a closed and valve 52 open. After drying, any dust particles that may have been stirred up in the collecting container are transported back into the sieve basket insert 24 via the ventilation line 49 when the vacuum is released by the air supply.

The entire device is designed so that it can be easily connected to other machines. The items to be washed can be fed in baskets, for example, via roller conveyors (not shown in the drawing). These baskets are then lifted vertically from the roller conveyor by a transport device and then moved over the drying device arranged on the side of the roller conveyor. After opening the lid 11a of the washing container, the basket can be lowered into the cleaning chamber.

The washing and drying process can be completed in a cycle time of usually 2 to 4 minutes. This cycle time can be reduced even further if two separate cleaning chambers are ^provided in a drying device, which are operated in tandem in parallel. In order to further reduce the machine's emissions, the entire device is located in a closed housing from which any solvent vapors that may escape are extracted via an internal air extraction system.

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Cleaning agents, propellants and air are in closed systems, which also prevents further environmental pollution. The machine therefore contributes in every way to reducing waste.

Claims (19)

Drying equipment in cleaning systems Protection claims 1. Drying device, in particular for mechanically processed workpieces such as turned and stamped parts (washing goods) in cleaning or degreasing systems, with a cleaning liquid circuit, in which at least one washing container (11) designed to build up a vacuum suitable for drying can be connected to Re miyüfiySkdHim&r \1G/, ule with WEmyStcns clficT vacuum pump with a rotary or rocking drive (12) movable laundry tray (16), characterized in that the washing container (11) can be connected abruptly to a vacuum storage device (70) during drying 2. Drying device according to claim 1, characterized in that the washing container (11) can be connected to the vacuum cleaner (70) and the vacuum pump. 3. Drying device according to claim 1, characterized in that the vacuum reservoir (70) can be acted upon by at least one further vacuum pump. 4. Drying device according to one of the preceding claims, characterized in that the vacuum reservoir can be separated from the vacuum pump(s) via a valve. Drying device according to one of the preceding claims, characterized in that after separation of the vacuum storage (70) and the vacuum pump, the vacuum pump dries the laundry. 6. Drying device according to one of the preceding claims, characterized in that the vacuum pump generates the vacuum in Vacuum reservoir (70) builds up before drying during the washing phase. 7. Drying device according to one of the preceding claims, characterized in that the washing container (11) with the cleaning chamber (10) can be hermetically sealed both from the atmosphere and from the cleaning liquid circuit. 8. Drying device according to one of the preceding claims, characterized in that the cleaning chamber (10) is permanently connected to the suction nozzle of the vacuum pump during drying. 9. Drying device according to one of the preceding claims, characterized in that a jet pump operated with a propellant is provided as the vacuum pump. 10. Drying device according to claim 9, characterized in that the jet pump is fed with a circulation pump (33) from a coolable propellant storage container (32). U. Drying device according to one of the preceding claims, characterized in that the washing container (11) can be ventilated during the drying process via a valve. 12. Drying device according to one of the preceding claims, characterized in that the washing container (11) can be connected to a collecting container (15) via a closure valve (14). 13. Drying device according to one of the preceding claims, characterized in that a sieve basket insert (24) is provided. 14. Drying device according to claim 13, characterized in that the sieve basket insert (24) can be moved horizontally in the collecting container (15) and can be moved out vertically therefrom via an opening that can be closed by means of a cover (15a). 15. Drying device according to claim 13 or 14, characterized in that the content of the strainer basket insert (24) can be connected to the negative pressure of the vacuum reservoir (70) or the vacuum pump. 16. Drying device according to one of the preceding claims, characterized in that the supplied air can be heated via a heat exchanger (54) before it is fed in from a heat source ( ^5r ). 17. Drying device according to one of the preceding claims, characterized in that solvents such as chlorinated hydrocarbons are used as cleaning liquid or propellant, which are cooled in the propellant storage container to a temperature close to the solidification point. 18. Drying device according to one of claims 1 to 16, characterized y C PvC M &Ggr;&idiagr; Z. C IClinCU) VJ SU a IJ l\C til ivjliti^j &igr; iujj lyiw. &igr; \, mi &ugr; is\. ^v~i^jv~..v.(wn mixed water and water cooled to a maximum temperature of 2° C in the propellant reservoir (32) are used as the propellant 19. Drying device according to one of the preceding claims, characterized in that the vacuum storage can be used as a vacuum still for regenerating the cleaning liquid.