WO1999023932A1

WO1999023932A1 - Method for drying goods and device for carrying through said method

Info

Publication number: WO1999023932A1
Application number: PCT/SE1998/002006
Authority: WO
Inventors: Åke LARSSON
Original assignee: Larsson Aake
Priority date: 1997-11-10
Filing date: 1998-11-06
Publication date: 1999-05-20
Also published as: SE511231C2; AU1182899A; EP1045664A1; SE9704098L; SE9704098D0

Abstract

The present invention relates to a method and a device for drying goods (4) which is cleaned in a cleaning chamber (2). At said method the drying process (C) is carried through after a disinfection process (B) has taken place in the cleaning chamber (2) by heating the goods (4) to a temperature of at least 85 °C, preferably a temperature of 92-95 °C, for at least one minute. During said drying process (C), the heat which has been generated during the disinfection process (B) and accumulated in the cleaning chamber (2), is utilized. Furthermore, cooling medium is during the drying process (C) supplied to the cleaning chamber (2), preferably to a portion (2d) thereof which is to be cooled, for condensing water vapour in said cleaning chamber (2).

Description

Method for drying goods and device for carrying through said method.

The present invention relates to a method and a device for drying goods which is cleaned and disinfected in a cleaning chamber.

CH- 602 202 describes a device for cleaning and disin- fecting goods. The cleaning and disinfection is carried through in a cleaning chamber, but no drying process takes place before the goods is removed therefrom.

US 2 390 757 defines a sterilizing device wherein the sterilized goods is dried in a drying process. US 3 704 170 and US 3 802 918 define dish washing machines wherein goods is washed with hot water. Dish washing machines are characterized by the fact that their main purpose is to flush away particles, albumin and starch at temperatures below 70°C. DE 12 55 254 also describes a dish washing machine wherein the goods is dried by feeding a cooling medium for condensing existing water vapour.

In contrast to dish washing machines according to the abovementioned publications, a disinfector is charac- terized by the fact that its main purpose is to discon- taminate goods and chamber with regard to bacteria at a temperature of at least 85°C during one minute. The amount of vapour produced in a disinfector at 85-95°C is so large that the amount of vapour in a dish washing machine in comparison is negligible.

Drying of goods after disinfection in a disinfector should be possible with an extra hot-air unit. Such units however, are expensive to acquire and operate. Furthermore, a fan device is required for ventilating the machine in question. This in turn, requires that the disinfector must be provided with a particle filter through which the evacuating air passes, such that scattering of not decontaminated bacteria to the surrounding air is prevented. Since all these requirements must be fulfilled, the use of an extra hot-air unit for drying after disinfection becomes an unrealistically expensive solution to the problem.

The object of the present invention is to simplify the prior art methods and devices for disinfection of goods . This is arrived at according to the invention by means of a new method, the characterizing measures of which are defined in subsequent claim 1 and by means of a new device having the characterizing features of subse- quent claim 17.

Since the new method and device utilize heat accumulated during the disinfection process and holding a temperature or more than 85°C and normally even a temperature of 92-95°C, while simultaneously condensing water vapour, a cheap and effective drying process is surprisingly obtained without any further heating or supply of heated air. It is namely surprising that the heat required for the disinfection is sufficient for effective drying of the goods during condensing of existing water vapour by means of a cooling medium.

The invention will be further described below with reference to the accompanying drawings. In the drawings, fig. 1 is a section through a device according to the invention; fig. 2 illustrates a portion of a condenser forming part of the device of fig. 1; fig. 3 is a section through members forming part of the device of fig. 1; figs . 4A and 4B illustrate a diagram of a complete process of treatment and a drying process included therein used in accordance with the invention; fig. 5 illustrates a device according to the invention which is used on another device than the one shown in fig. 1.

Fig. 1 schematically illustrates a device for cleaning and disinfection 1 in the form of a so called dish disinfector. This device has a cleaning chamber 2 which is formed of primarily six members, namely a bottom 2a, a roof 2b, two side walls 2c, a rear wall 2d and a door 2e. In said chamber 2 there is provided a basket 3 for goods 4 to be washed and disinfected and beneath said basket 3 there is located a movable member 5 with nozzles 6 for flushing the goods 4 from below. A nozzle 7 is provided at the top in the chamber 2 for flushing the goods 4 from above.

A water collecting container 8 is located below on the device 1 such that water can flow down from the chamber 2 and be collected in said container 8. A water circulating system 9 is adapted for sucking up water from the water collecting container 8, heating said water and bring it to flow to the nozzles 6 and 7. For carrying through this, the water circulating system 9 includes a conduit system 10 which is connected to the water collecting container 8 and opens into nozzles 6 and 7. Water is sucked into the conduit system 10 and is discharged therefrom by means of a circulation pump 11 and said water is brought to pass a heating device 12 wherein it is heated. Heating to disinfection temperature may be carried through alternatively with a so called steam or vapour generator or with centrally produced steam or vapour without water circulation.

Water may be discharged from the water collecting container 8 and fed to a drain 13 through a discharge pipe 14 with a discharge pump 15. A cold-water conduit 16 is connected to the device 1 and extends into the chamber 2 and is also connected to a distributor pipe or spray pipe 17. This is located at the top in the chamber 2 close to the rear wall 2d and extend along said rear wall. The spray pipe 17 has a se- ries of holes 18 or nozzles located beside each other for feeding cold water towards the rear wall 2d such that a curtain 19 of cold water is formed therealong which can cool said rear wall 2d and which can condense water vapour present in the chamber 2. A hot-water conduit 20 is also connected to the device 1, extends into the chamber 2 and is connected to a nozzle 21 for the discharge of hot water to said chamber 2 In the cold-water conduit 16 there is provided a valve device 22, preferably including a magnetic valve, and in the hot-water conduit 20 another valve device 23, preferably also a magnetic valve. The valve devices 22, 23 are controlled by a programmable control device 24 such that the cold-water and hot-water conduits 16, 20 respectively, are opened and closed in accordance with a program selected in the control device 24.

An air-cooled condenser 25 is located outside the chamber 2 and preferably attached to the rear wall 2d. Down below, the condenser 25 is connected to lower portions of the chamber 2 through one or more connecting conduits 26, such that water vapour can flow out of the chamber 2 into lower portions of the condenser 25 and rise upwards therein through a passage 40, while the water vapour or at least substantial parts thereof is/are condensed by means of pressurized air 28. The condenser 25 has an opening 41 at the top, whereby it is prevented that an overpressure is generated therein and thus, in the chamber 2. The passage 40 may have the shape of a labyrinth (not shown) for increasing the cooling surface and retarding the through-flow speed of the water vapour.

The condenser 25 may have openings 27 through which the water vapour flowing upwards in the passage 40 can eject cooling air 28 from the surroundings into said passage 40, whereby the condensing capacity of the condenser 25 is improved.

The condensate obtained in the condenser 25 may be fed to the chamber 2 through the connecting conduits 26. In the water collecting container 8 there is preferably provided a water-flow brake device 29 which is adapted to prevent the circulation pump 11 from sucking out so much water from the water collecting container 8 that air reach into the water circulating system 9 through said container 8. The water-flow brake device 29 may be designed in various ways, of which one is shown in fig. 3. The illustrated embodiment of the water-flow brake device 29 includes a shield 30 and a net 31 located beneath said shield 30. The net 31 has a bottom 32 and upwardly directed sides 33 through which the net 31 is located on the shield 30. The shield 30 is located above a discharge pipe 34 which is located on the bottom 32 of the net 31 and connected to the conduit system 10 of the water circulating system 9.

This water-flow brake device 29 prevents water from flowing from above directly down into the conduit sys- tem 10 and increased suction area provides for a lower water speed. Instead, the water is forced to flow under the shield 30 from the sides through the net 31, into the through-flow space 35 defined by the shield 30 and the net 31 and through said space 35 and the discharge pipe 34 into the conduit system 10.

For preventing turbulence when the water flows through said through-flow space 35, there is in said space 35 under the shield 30 provided a turbulence preventing device 36, e.g. in the form of a shield which is horizontally or substantially horizontally oriented. A turbulence preventing device 37 may also be located in the discharge pipe 34 for preventing turbulence or whirling therein. Said latter turbulence preventing device 37 may be a shield which is mounted vertially or substan- tially vertically in the discharge pipe 34.

The control device 24 can be programmed for carrying through an initial dish washing process A. This process starts with a preflushing of the goods 4, a principal washing of the goods 4 and a subsequent flushing of the goods 4. The follows a disinfecting process B which starts with the control device 24 operating the valve device 23 to open the hot-water conduit 20 such that hot water at a temperature of about 63°C is fed into the chamber 2. Thereafter, the heating device 12 and the circulation pump 11 are activated and the hot water in the chamber 12 is heated to a disinfection temperature of a least 85°C, preferably to about 92-95°C, and this temperature is maintained for at least one minute for the required disinfection of the goods 4.

The control device 24 may also be programmed to start a drying process C after said disinfection process B, pre- ferably immediately after the disinfection process B, for effective drying of the goods 4 and of inner portions of the chamber 2, since said goods 4 and portions of the chamber 2 are covered with hot water. The control device 24 is programmed to start the drying process C with the valve device 22 being activated to open the cold-water conduit 16 such that said conduit is either kept conti- nously open for a certain drying time or is opened periodically for a certain drying time and during the end of the drying period to once again close the cold-water con- duit 16. By feeding cold water to the chamber 2 during said drying period, the water vapour generated in the chamber 2 during the preceding process and/or processes A and/or B is condensed. During the same drying period, the heat of over 85°C, preferably 92-95°C, which has been generated for carrying through the disinfection process B and which during said process has been accumulated in the goods 4 and in the walls 2a-2e of the chamber 2, is utilized for drying said goods 4 and said walls 2a-2e (and eventually other portions of or in the chamber 2) . It has been noticed that said condensation and use of the intense heat provide for an effective drying process C without the need for heating the air in the chamber or feeding hot air thereto .

As has been mentioned above and as is apparent from fig. 4B, the control device 24 may be programmed to control the valve device 22, during the drying process C, to open the cold-water conduit 16 periodically such that cooling water, during the cooling-medium supply period Cl, condenses water vapour in the chamber 2 and also cools the rear wall 2d, while the rear wall 2d thus cooled, during supply interrupting periods C2 , condenses water vapour without supply of cooling water. Hereby, effective condensing of water vapour is obtained with the least possible cooling-water consumption.

The cooling-medium supply periods Cl and the supply interrupting periods C2 can be of equal length and each such period may last 20-40, preferably about 30 seconds. Each drying process C may last four minutes and include four cooling-medium supply periods Cl and three supply interrupting periods C2 , whereby the temperature of the goods 4 and in the chamber 2 may be reduced to below about 45°C. At this temperature, the chamber 2 can be opened without any risk of water vapour thereby escaping and the goods 4 can be removed from the chamber 2 in dry or substantially dry condition, the walls 2a-2e of said chamber 2 also being dry or substantially dry. The method and the device described above may alternatively be used at a cleaning and disinfecting device in the form of a so called flush disinfector (see fig. 5) wherein goods such as bedpans, wash bowls, urinals and similar are flushed with water before disinfection. The flusing water is supplied by means of a flushing device

38 and is removed or discharged through a drain or discharge device 39. Then, a disinfecting process B and a drying process C are carried through as described above. The invention is not limited to the method and de- vice described above, but may vary within the scope of the subsequent claims. As examples of alternative embodiments it should be mentioned that the device 1 for cleaning and disinfection may be of another type than described, another cooling medium than cooling water may be used, said cooling medium may be supplied in other ways than described and to other members and portions for cooling than those described, the exterior condenser may be of another type than described and the water-flow brake device may be designed in other ways than described.

Claims

Claims :

1. Method for drying goods (4) which is cleaned in a cleaning chamber (2), c h a r a c t e r i z e d i n that the drying process (C) is carried through after cessation of a disinfecting process (B) in the cleaning chamber (2) including heating the goods (4) to a temperature of at least 85┬░C, preferably a temperature of 92-95┬░C, for at least one minute, that the heat generated at the disinfecting pro- cess (B) and accumulated in the cleaning chamber (2) is utilized during said drying process (C) , and that cooling medium is supplied during the drying process (C) to the cleaning chamber (2) , preferably a portion (2d) thereof which can be cooled, for conden- sing water vapour present therein.

2. Method according to claim 1, c h a r a c t e r i z e d i n that cooling medium is supplied periodically during the drying process (C) for bringing said cooling medium during supply periods partly to condense water vapour and partly to cool a portion (2d) which can be cooled in the cleaning chamber (2) and for utilizing cold from the cooled portion (2d) for condensing water vapour between said supply periods .

3. Method according to claim 2, c h a r a c t e - r i z e d i n that the supply of cooling medium during a drying process (C) occurs during several supply interrupting periods (C2) .

4. Method according to claim 2, c h a r a c t e r i z e d i n that the cooling-medium supply periods (Cl) during a drying process (C) are chosen to be of equal length or of substantially equal length and that the supply interrupting periods (C2) during the same drying process are chosen to be of equal length or of substantially equal length.

5. Method according to claim 3 or 4, c h a r a c t e r i z e d i n that cooling medium during each cooling-medium supply period (Cl) is supplied to the portion (2d) which can be cooled for 20-40 seconds, pre- ferably about 30 seconds, and that the supply of cooling medium is interrupted during each supply interrupting period (C2) for 20-40 seconds, preferably about 30 seconds.

6. Method according to any of claims 3-5, c h a - r a c t e r i z e d i n that the drying process (C) is chosen to be four minutes long or substantially four minutes long and that the drying process (C) is chosen to include four cooling-medium supply periods (Cl) and three supply interrupting periods (C2) .

7. Method according to any of claims 3-6, c h a r a c t e r i z e d i n that the number of cooling- - edium supply periods (Cl) and supply interrupting periods (C2) during the drying process (C) is chosen such that the temperature in the cleaning chamber (2) is reduced from a disinfection temperature of at least 85┬░C, preferably 92-95┬░C, to a temperature below about 45┬░C.

8. Method according to any preceding claim, c h r a c t e r i z e d i n that the drying process (C) is initiated immediately after the disinfection process (B) and without selecting any other treating process between the disinfection process (B) and the drying process (C) .

9. Method according to any preceding claim, c h a - r a c t e r i z e d i n that no heating of and/or no supply of hot-air to the cleaning chamber (2) occurs during the drying process (C) .

10. Method according to any preceding claim, c h a r a c t e r i z e d i n that generation of an over- pressure in the cleaning chamber (2) before the drying process (C) is prevented by feeding water vapour generated in the cleaning chamber (2) to a condenser (25) which is located outside said cleaning chamber (2) and in which said water vapour or at least substantial parts thereof is/are condensed by means of cooling air.

11. Method according to claim 10, c h a r a c t e - r i z e d i n that water vapour is brought to flow upwards in the condenser (25) while it is condensed by means of cooling air.

12. Method according to any preceding claim, c h a r a c t e r i z e d i n that cooling medium during the drying process (C) is supplied to such a portion for cooling which consists of at least one wall (2d) of the cleaning chamber (2) such that water vapour can be condensed by means of said wall (2d) .

13. Method according to claim 12, c h a r a c t e - r i z e d i n that cooling medium during the drying process (C) is supplied to said wall (2d) such that a curtain (19) of cooling medium is formed along at least the major part of said wall (2d) .

14. Method according to any preceding claim, c h a - r a c t e r i z e d i n that the drying process (C) is carried through by feeding cooling medium in the form of cold water to the cleaning chamber (2) through a cold- -water conduit (16) by opening a valve device (22), and the valve device (22) is opened for feeding cold water into the cleaning chamber (2) in connection with another process or other processes than the drying process (C) .

15. Method according to any preceding claim, c h a r a c t e r i z e d i n that a valve device (22) is controlled to open and close a cooling-medium conduit (16) for initiating and finishing said drying process (C) .

16. Method according to any preceding claim, c h a r a c t e r i z e d i n that said drying process (C) is carried through for drying goods (4) which have been washed and disinfected with water which circulates in the cleaning chamber (2), or of goods (4) which have been flushed with water and then removed from the cleaning chamber (2) and thereafter disinfected.

17. Device for carrying through a method for drying goods (4) which are cleaned and disinfected in a cleaning chamber (2) , c h a r a c t e r i z e d i n that a heating device (12) is provided for heating water to a disinfection temperature of at least 85┬░C, preferably 92-95┬░C, for at least one minute, for using this heated water during a disinfection process (B) for disinfection of the goods (4) in the cleaning chamber (2) , that a control device (24) can be programmed to carry through a drying process (C) after said disinfection process (B) during which the goods (4) is dried, that the control device (24) is provided to operate a valve device (22) at the initiation of the drying pro- cess (C) to open a cold-water conduit (16) for supplying cold water to the cleaning chamber (2) for condensing water vapour in said chamber (2) , that the control device (24) is provided to operate the valve device (22) at the end of the drying process (C) to close the cold-water conduit (16) for interrupting the supply of cold water to the cleaning chamber (2), and that the control device (24) can be programmed such that heat which has been accumulated in the cleaning chamber (2) during the disinfection process (B) can be utili- zed for drying during the drying process (C) .

18. Device according to claim 17, c h a r a c t e r i z e d i n that the control device (24) can be programmed to operate the valve device (22) during a drying process (C) to open and close the cold-water conduit (16) periodically such that cold water periodically cools at least a portion (2d) to be cooled of and/or in the cleaning chamber (2) and such that cold from said portion (2d) to be cooled can be utilized for condensing water vapour in the cleaning chamber (2) when the supply of cooling medium is interrupted.

19. Device according to claim 17 or 18, c h a r a c t e r i z e d i n that the control device (24) can be programmed to operate the valve device (22) during a drying process (C) to a) keep the cold-water conduit (16) open during a plurality of cooling-medium supply periods (Cl) , and b) close the cold-water conduit (16) after each cooling-medium supply period (Cl) and keep it closed during a plurality of supply interrupting periods

(C2) .

20. Device according to any of claims 17-19, whereby a condenser (25) is provided outside the cleaning chamber (2) , c h a r a c t e r i z e d i n that the condenser is an air-cooled condenser (25) which down below is connected to the cleaning chamber (2) through one or more connecting conduits (26) for feeding water vapour from the cleaning chamber (2) to lower portions of the condenser (25) , and that the condenser (25) has at least one through-flow passage (40), preferably with the shape of a labyrinth, through which water vapour can flow upwards while it is cooled by cooling air and condensed.

21. Device according to claim 20, c h a r a c t e r i z e d i n that the condenser (25) has openings (27) through which air (28) from the surroundings may be ejected into the passage (40) by the flow of water vapour therein.

22. Device according to any of claims 17-20, c h a r a c t e r i z e d i n that a portion which can be cooled by cold water consists of at least one of the walls (2c, 2d) of the cleaning chamber (2), preferably a rear wall (2d), and that the cold-water conduit (16) in a manner known per se includes a spray pipe (17) which is located inside the cleaning chamber (2) and which forms a curtain (19) of cold water along at least the major part of said wall (2d) .

23. Device according to any of claims 17-22, c h a r a c t e r i z e d i n that the control device (24) can be programmed to operate the valve device (22) such that cold water is fed into the cleaning chamber (2) be- fore the drying process (C) for heating said cold water and use the heated water for washing said goods (4) .

24. Device according to any of claims 17-23, whereby a water collecting container (8) is provided for collecting water from the cleaning chamber (2) and whereby a circulation pump (11) is mounted in a water circulating system (9) for sucking water from the water collecting container (8) and bring said water to flow back to the cleaning chamber (2) for use therein, c h a r a c t e r i z e d i n that the water collecting container (8) has a water-flow brake device (29) which prevents the circulation pump (11) from sucking out so much water from the water collecting container (8) that air enters the water circulating system (9) .

25. Device according to claim 24, c h a r a c t e - r i z e d i n that the water-flow brake device (29) has a shield (30) and under said shield (30) a net (31) with a bottom (32) and upwardly directed sides (33), whereby the shield (30) and the net (31) together define a through-flow space (35) , whereby a discharge pipe (34) is provided at the bottom (32) of the net (31) beneath the shield (30) , whereby the shield (30) prevents water from flowing from above directly into the discharge pipe (34) and whereby the net (31) permits water to flow into the through-flow space (35) , and that at least one tur- bulence preventing device (36 and/or 37) is located in the through-flow space (35) under the shield (30) and/or in the discharge pipe (34) for preventing water from forming whirls under the shield (30) in the through-flow space (35) and/or in the discharge pipe (34) .

26. Device according to any of claims 17-24, c h a r a c t e r i z e d i n that the control device (24) is provided to control a drying process (C) in a cleaning chamber (2) wherein there is provided a device (5-7) for washing the goods (4) with water which can be recycled.

27. Device according to any of claims 17-24, c h a r a c t e r i z e d i n that the control device (24) is provided to control a drying process (C) in a cleaning chamber (2) wherein there is provided a flushing device (38) for flushing the goods (4) , whereby a discharge device (39) is provided to permit discharge of the flushing water before the disinfection of the goods (4) .