Warewasher comprising a drying system and method for operating such a warewasher

Abstract

A warewasher (1) provided as a box-type warewasher and a method for operating such a warewasher (1) are provided. In accordance with the warewasher and method, during the adsorption phase, air is guided from the treatment chamber (2) of the machine (1) through a drying unit (40) in such a way that moisture from the airflow is absorbed by a dry material, wherein the air is then fed again to the treatment chamber (2). Furthermore, the drying device is arranged above the treatment chamber (2) so as to effectively prevent penetration of splashed water into the drying device (40).

Claims

1. A warewasher comprising: a treatment chamber (2), into which and from which items can be introduced and removed manually; a tank (12), into which liquid from the treatment chamber (2) can flow as a result of gravity; a washing system comprising a washing pump (13) and a washing line system (16) for conveying washing liquid during a washing phase from the tank (12) and for spraying the washing liquid through washing jets (11a, 11b) in the treatment chamber (2); a fresh water rinsing system comprising at least one rinsing pump (14; 14a, 14b) and at least one rinsing line system (17, 17a, 17b) for conveying rinsing liquid during a fresh water rinsing phase from a fresh water feed device and for spraying the rinsing liquid through rinsing jets (15a, 15b) in the treatment chamber (2); a drying device (40) for removing moisture from drying air circulating in the treatment chamber (2), wherein the drying device (40) has at least one sorption unit (41) having a reversibly dehydratable dry material as well as at least one fan (44) for circulating air in such a way that air is guided through the sorption unit (41) and is then fed again to the treatment chamber (2), wherein the drying device (40) is arranged above the treatment chamber (2); wherein the drying device (40) has an air inlet (40a), which is connected via an inlet line (42) to the treatment chamber, wherein the inlet line (42) is connected laterally or from above to the treatment chamber (2); wherein the drying device (40) has an air outlet (40b), which is connected via an outlet line (43) to the treatment chamber (2), wherein the outlet line (43) is connected laterally or from above to the treatment chamber (2); wherein the drying device (40) further has a heating unit (45) for heating the reversibly dehydratable dry material, and wherein the heating unit (45) has an output of 1 to 14 kW; wherein the heating unit (45) has a multiplicity of heating elements, which are arranged at uniform distances within the reversibly dehydratable dry material.

2. A warewasher comprising: a treatment chamber (2), into which and from which items can be introduced and removed manually; a tank (12), into which liquid from the treatment chamber (2) can flow as a result of gravity; a washing system comprising a washing pump (13) and a washing line system (16) for conveying washing liquid during a washing phase from the tank (12) and for spraying the washing liquid through washing jets (11a, 11b) in the treatment chamber (2); a fresh water rinsing system comprising at least one rinsing pump (14; 14a, 14b) and at least one rinsing line system (17, 17a, 17b) for conveying rinsing liquid during a fresh water rinsing phase from a fresh water feed device and for spraying the rinsing liquid through rinsing jets (15a, 15b) in the treatment chamber (2); a drying device (40) for removing moisture from drying air circulating in the treatment chamber (2), wherein the drying device (40) has at least one sorption unit (41) having a reversibly dehydratable dry material as well as at least one fan (44) for circulating air in such a way that air is guided through the sorption unit (41) and is then fed again to the treatment chamber (2), wherein the drying device (40) is arranged above the treatment chamber (2); wherein the drying device (40) has an air inlet (40a), which is connected via an inlet line (42) to the treatment chamber, wherein the inlet line (42) is connected laterally or from above to the treatment chamber (2); wherein the drying device (40) has an air outlet (40b), which is connected via an outlet line (43) to the treatment chamber (2), wherein the outlet line (43) is connected laterally or from above to the treatment chamber (2); wherein the warewasher (1) has a first splash protection apparatus (50a) between the air inlet (40a) and the treatment chamber (2) to limit water entry from the treatment chamber (2) into the air inlet (40a) and/or a second splash protection device (50b) between the air outlet (40b) and the treatment chamber (2) to limit water entry from the treatment chamber (2) into the air outlet (40b).

3. The warewasher (1) as claimed in claim 1, wherein the sorption unit (41) has a thickness (D) of 2 to 100 mm along the direction of flow of the airflow guided from the treatment chamber (2).

4. A warewasher comprising: a treatment chamber (2), into which and from which items can be introduced and removed manually; a tank (12), into which liquid from the treatment chamber (2) can flow as a result of gravity; a washing system comprising a washing pump (13) and a washing line system (16) for conveying washing liquid during a washing phase from the tank (12) and for spraying the washing liquid through washing jets (11a, 11b) in the treatment chamber (2); a fresh water rinsing system comprising at least one rinsing pump (14; 14a, 14b) and at least one rinsing line system (17, 17a, 17b) for conveying rinsing liquid during a fresh water rinsing phase from a fresh water feed device and for spraying the rinsing liquid through rinsing jets (15a, 15b) in the treatment chamber (2); a drying device (40) for removing moisture from drying air circulating in the treatment chamber (2), wherein the drying device (40) has at least one sorption unit (41) having a reversibly dehydratable dry material as well as at least one fan (44) for circulating air in such a way that air is guided through the sorption unit (41) and is then fed again to the treatment chamber (2), wherein the drying device (40) is arranged above the treatment chamber (2); wherein the drying device (40) has an air inlet (40a), which is connected via an inlet line (42) to the treatment chamber, wherein the inlet line (42) is connected laterally or from above to the treatment chamber (2); wherein the drying device (40) has an air outlet (40b), which is connected via an outlet line (43) to the treatment chamber (2), wherein the outlet line (43) is connected laterally or from above to the treatment chamber (2); wherein the drying device (40) has a first air distributor (51), which is arranged between the fan (44) and the sorption unit (41) and is designed to direct the airflow perpendicular to an entry surface of the sorption unit (41).

5. The warewasher (1) as claimed in claim 4, wherein the first air distributor (51) consists of a multiplicity of air lamellae.

6. The warewasher (1) as claimed in claim 4, wherein the drying device (40) further has a second air distributor (52), which is arranged between the sorption unit (41) and the treatment chamber (2), wherein the second air distributor (52) is arranged opposite the first air distributor (51) in such a way that the airflow is distributed uniformly over the entire dry material of the sorption unit (41).

7. The warewasher (1) as claimed in claim 1, wherein the reversibly dehydratable dry material consists of 0.3 to 3 kg of zeolite-containing material.

8. The warewasher (1) as claimed in claim 7, wherein the zeolite-containing material of the dry material is provided in the form of a granulate having a diameter of 0.5 to 10 mm.

9. The warewasher (1) as claimed in claim 1, wherein the drying device (40) further has a heat exchanger unit, which is connected to the sorption unit (41) in such a way that, when air is circulated, at least part of the airflow guided through the sorption unit (41) also passes through the heat exchanger unit.

Description

(1) Exemplary embodiments of the warewasher according to the invention will be described in greater detail hereinafter with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a schematic view of a warewasher, in particular a commercial warewasher, in the form of a box-type warewasher in accordance with a first embodiment of the invention;

(3) FIG. 2 shows a schematic view of a warewasher, in particular a commercial warewasher, in the form of a box-type warewasher in accordance with a second embodiment of the invention;

(4) FIG. 3 shows a schematic view of a first embodiment of a drying unit of the warewasher according to the invention; and

(5) FIG. 4 shows a schematic view of a second embodiment of a drying unit for a warewasher according to the invention.

(6) The invention relates to warewashers, in particular commercial warewashers for crockery or utensils, in the form of a box-type warewasher. They usually contain program control devices for controlling at least one cleaning program and a treatment chamber 2, which can be closed by a door (not shown) or a hood (not shown), in a machine housing for receiving items to be cleaned (not shown), such as crockery, cutlery, pots, pans, trays, transport containers, racks, preparation tools and also class I medical devices, in particular bedpans, and surgical instruments or components thereof.

(7) A washing tank 12 for receiving sprayed liquid from the treatment chamber 2 is located beneath the treatment chamber 2. A washing pump 13 is provided to convey washing liquid from the washing tank 12 through a washing liquid line system 16 to washing jets 11a, 11b (e.g., from nozzles), which are directed in the treatment chamber 2 onto the area of the items to be cleaned. The sprayed washing liquid falls back into the washing tank 12 as a result of gravity. The washing tank 12, the washing pump 13, the washing liquid system 16 and the washing jets 11 therefore, together with the treatment chamber 2, form a washing liquid circuit. The washing liquid line system 16 connects the delivery side of the washing pump 13 to the washing jets 11a, 11b.

(8) Further, a rinsing system for conveying rinsing liquid by means of a rinsing pump 14 through a rinsing line system 17 to rinsing jets 15a, 15b is provided, said rinsing jets being directed in the treatment chamber 2 onto the area of the items to be cleaned. The sprayed rinsing liquid falls from the treatment chamber 2 into the washing tank 12 as a result of gravity. The rinsing liquid system 17 connects the delivery side of the rinsing pump 14 to the rinsing jets 15a, 15b.

(9) The washing jets 11a, 11b and the rinsing jets 15a, 15b can be arranged within the treatment chamber in the areas above and/or below the area of the items to be washed and, if desired, also to the side of said area, and in each case can be directed towards the area in which the items to be washed are positioned.

(10) A multiplicity of washing jets 11a is preferably provided on at least one upper washing arm, a multiplicity of washing jets 11b is preferably provided on a lower washing arm, a multiplicity of rinsing jets 15a is preferably provided on at least one upper rinsing arm, and a multiplicity of rinsing jets 15b is preferably provided on at least one lower rinsing arm.

(11) Before rinsing liquid is sprayed during the final rinse phase, a quantity of washing liquid corresponding to the rinsing liquid is drained from the washing tank 12 by means of a draining pump 5, of which the intake side is attached via a discharge line to a sump of the washing tank. If, before the warewasher 1 formed as a box-type warewasher is started for the first time, the washing tank 12 is empty, it must first be filled with fresh water via a fresh water line (not shown) or with fresh water or another rinsing liquid or washing liquid by means of the rinsing system and the rinsing pump 14 thereof.

(12) The rinsing liquid may be fresh water or fresh water mixed with a rinsing aid. The washing liquid by contrast contains a cleaning agent (detergent), which is preferably automatically added in a metered manner to the liquid contained in the washing tank 12 by a cleaning agent metering apparatus (not shown). The above-mentioned program control device controls the washing pumps 13, the rinsing pump 14, the draining pump 5, the rinsing aid metering pump (not shown) and the cleaning agent solution pump (not shown) in accordance with the cleaning program selected by an operator at the program control device. At least one cleaning program is provided, and preferably a plurality of cleaning programs that can be selected electively.

(13) From the embodiment of the warewasher 1 according to the invention illustrated in FIG. 1, a rinsing pump 14 is also attached via its intake side to an outlet of a boiler 22. The boiler 22 furthermore comprises an inlet, which is connected to a fresh water feed line 30 and via which either fresh water or fresh water with rinsing aid added by metering is fed to the boiler 22. In the boiler 22, the liquid fed via the inlet (pure fresh water or fresh water with rinsing aid added by metering) is heated once a process sequence has been specified. By means of the rinsing pump 14 attached via its intake side to the boiler outlet, the rinsing liquid heated in the boiler 22 can be fed for example during a fresh water rinsing phase to the rinsing jets 15a and 15b via the rinsing line system 17. The rinsing jets 15a or 15b are arranged in the treatment chamber 2 in order to spray the rinsing liquid heated in the boiler 22 over the items to be washed in the treatment chamber 2. Of course, it is also conceivable for pure fresh water to be fed to the boiler via the inlet into the fresh water feed line 30, said fresh water being supplemented with a rinsing aid added in a metered manner after heating in the boiler.

(14) In the embodiment of the warewasher 1 according to the invention illustrated in FIGS. 1 and 2, the rinsing system has a preferably electrically operated steam generator 39, which, as illustrated in the figures, can be integrated into the boiler 22 for example. In this case, a corresponding steam outlet 46 of the steam generator 39 is formed on the upper area of the boiler 22. The steam outlet 46 of the steam generator 39 is connected via a steam line 46a at a point positioned above the washing tank 12 to the treatment chamber 2, in order to introduce as required into said treatment chamber the steam generated in the steam generator 39. The outlet opening of the steam line 40b is preferably located between the upper jets 11a, 15a of the washing system or fresh water rinsing system and the lower jets 11b, 15b. Of course, other positions are also possible.

(15) A heater 47 is located in the boiler 22, which in accordance with the embodiments illustrated in FIGS. 1 and 2 is not only used to heat the rinsing liquid, but also to generate steam as required. Furthermore, a level sensor 48 can be arranged in or on the boiler 22 and for example controls a valve 49 of the fresh water line 30.

(16) The warewasher 1 according to the invention further has a drying device 40 for removing moisture from the drying air circulating in the treatment chamber 2, either continuously or as required. The drying device 40 has at least one sorption unit having a reversibly dehydratable dry material. This sorption unit 41 is normally a container in which a reversibly dehydratable dry material is filled. This dry material is preferably a sorption agent, which comprises zeolite. In particular, type Y zeolite is suitable as dry material, since this material is particularly stable, even under extreme hydrothermal conditions. The drying device further comprises at least one fan 44 for circulating air as required, in such a way that at least part of the air is guided from the treatment chamber 2 via an air inlet 40a through the sorption unit 41 and is then fed again to the treatment chamber 2 via an air outlet 40b.

(17) As can be deduced in particular in FIGS. 1 and 2, the drying device 40 is arranged above the treatment chamber 2. In other words, the drying device 40 with the fan 44 and the sorption unit 41 is preferably assembled on the top of the warewasher 1. This has the advantage for example that the above-mentioned washing liquid can only reach the interior of the drying device 40 with difficulty and therefore flows back exclusively into the washing tank 12 under the action of gravity. The dry material located in the sorption unit 41 is therefore effectively protected against splashed water and condensation water.

(18) The air inlet 40a of the drying device 40 is preferably connected via an inlet line 42 to the treatment chamber 2, wherein the inlet line 42 is connected from the side (FIG. 2) or from above (FIG. 1) to the treatment chamber 2. As an equivalent thereto, the air outlet 40b of the drying device is preferably connected via an outlet line 43 to the treatment chamber 2, wherein the outlet line 43 is connected from the side (FIG. 2) or from above (FIG. 1) to the treatment chamber 2. It should be mentioned at this juncture that the inlet or outlet lines 42, 43 may each have a valve for closing the connection between the treatment chamber and drying device 40 as required. By means of the inlet or outlet lines 42, 43, air can be circulated with the aid of the associated fan 44 as required in such a way that at least part of the air is drawn from the treatment chamber 2 and is fed via the inlet line 42 to the sorption unit 41. This air drawn from the treatment chamber 2 is then guided through the sorption unit 41 and the dry material and is then fed again to the treatment chamber 2 via the outlet 40b of the drying unit 40 and via the outlet line 43.

(19) In order to be able to regenerate the dry material of the sorption unit 41 during the desorption phase, it may be necessary, as already discussed, to heat the dry material accordingly. For this purpose, a heating device 45, which for example is electrically operated, is associated with the sorption unit 41 in the embodiments of the warewasher 1 according to the invention illustrated in drawings 1 and 2 and is designed to heat the dry material of the sorption unit 41 during a desorption phase or immediately before initiation of the desorption phase as required. The sub-process of desorption is carried out subsequently to the absorption phase, more specifically by feeding heat, for example in the form of electrical energy, water vapor, gas or hot water, to the sorption unit 41. At the same time or at a different time, air from the treatment chamber 2 of the warewasher 1 is blown through the sorption unit 41 in the desorption phase with the aid of the fan 44 via the inlet line 43 and absorbs the water desorbed in the form of water vapor from the dry material.

(20) The heating unit 45, illustrated merely schematically, may have a multiplicity of heating elements, which are arranged at a uniform distance within the reversibly dehydratable material. Here, the heating elements may be heating rods or heating plates for example, which are distributed over the entire volume of the sorption unit 41. Due to the strong absorption forces with respect to water, the dry material should be heated for example to more than 300 in order to obtain the lowest possible residual moisture content within the dry material. The multiplicity of heating elements (not illustrated) should therefore in particular be removed far enough from the housing walls of the drying device 40, such that said housing walls are not damaged by the high temperatures of up to 400.

(21) Schematic views of two different embodiments of the drying device 40 are illustrated in FIGS. 3 and 4. Here, the drying devices are connected via an air inlet 40a, and also via an air outlet 40b, to the treatment chamber 2. In order to effectively protect the sorption unit 41 against splashed water from the treatment chamber 2, the drying device 40 of the warewasher 1 has a first splash protection apparatus 50a between the air inlet 40a and the treatment chamber 2. Additionally or alternatively, the warewasher may have a second splash protection apparatus 50b between the air outlet 40b and the treatment chamber 2. The splash protection apparatuses illustrated schematically in FIGS. 3 and 4 are curved lines, protective covers or lines with an obstacle for example. Of course, the splash apparatuses are not limited to the exemplary embodiments illustrated.

(22) Inside the drying unit 40, a sorption unit 41 is located, which consists of a reversibly dehydratable dry material that is held by a housing structure (for example perforated sheets), which is not illustrated. Here, the sorption unit 41 is formed in particular in such a way that it has a thickness D of 2 to 100 mm, preferably 10 to 50 mm and more preferably to 40 mm, along the direction of flow of the airflow guided from the treatment chamber 2. The thickness of 2 to 100 mm ensures that the moist machine air is sufficiently dried without having to accept an excessively high flow resistance.

(23) The drying device 40 advantageously has a first air distributor 51, which is arranged between the fan 44 and sorption unit 41 and is designed to direct the airflow perpendicular to an entry surface of the sorption unit 41. In the embodiment according to FIG. 3, the first air distributor 51 accordingly has a multiplicity of air lamellae, which are curved in such a way that the airflow conveyed by the fan 44 is deflected at an angle of approximately 90 onto the sorption unit 41. The individual air lamellae here increase in size with increasing distance from the fan 44, whereby a uniform distribution of the airflow is ensured over the entire length of the sorption unit 41. The situation is similar with the air distributor 51 illustrated in FIG. 4, which is formed as a grid. With increasing distance from the fan 44, the thickness of the grid that has to be penetrated by the airflow in order to reach the sorption unit 41 reduces. It is again thus ensured that air also flows in equal proportions through the rear areas (on the right-hand side in the illustration). In other words, the flow resistance of the first air distributor illustrated in FIG. 4 decreases with increasing distance from the fan 44, whereby a uniform distribution of the airflow within the sorption unit 41 is ensured.

(24) The drying device 40 may further have a second air distributor 52, as is illustrated in FIG. 3 for example. The second air distributor 52 is preferably arranged between the sorption unit 41 and the treatment chamber 2. Here, the second air distributor 52 is arranged in relation to the first air distributor 51 in such a way that the airflow is distributed uniformly over the entire dry material of the sorption unit 41. More specifically, the airflow within the sorption material 41 can preferably be influenced by the second air distributor 52. For this purpose, the second air distributor is preferably formed as a perforated sheet or slotted sheet, wherein said sheet has an inhomogeneous distribution of openings. At points with a plurality of openings or larger openings, an increased airflow can therefore be forced through the sorption unit 41, whereas there is a reduced flow in the sorption unit 41 as a result of the increased flow resistance at points with fewer or smaller openings or slits. Due to a clever combination of the first and second air distributors 51, 52, a particularly homogeneous distribution of the airflow can be achieved over the entire dry material of the sorption unit 41.

(25) The method according to the invention for operating a warewasher 1 provided as a box-type warewasher will be explained in greater detail hereinafter on the basis of the exemplary embodiments illustrated in FIGS. 1 to 4:

(26) In a first method step, during an absorption phase, air is guided from the treatment chamber 2 through a sorption unit 41 having a reversibly dehydratable dry material, in such a way that the dry material absorbs moisture from the airflow, wherein the air is then fed again to the treatment chamber 2. During this absorption phase, in which moisture from air removed from the treatment chamber 2 is adsorbed by the dry material of the sorption unit 41, adsorption heat is also released, as a result of which the air, which has been guided through the sorption unit 41, is accordingly heated. The hot air dried once it has passed through the sorption unit 41 is fed back into the treatment chamber 2 of the warewasher 1 and can be used to dry the washed items received in the treatment chamber 2. In this regard, it is preferable if the adsorption phase of the sorption unit 41 takes place at the same time as the drying phase of the warewasher 1 or chronologically overlaps with the drying phase of the warewasher 1 in order to be able to use the heat released during the adsorption of moisture from the dry material of the sorption unit 41 to dry the washed items. Due to the higher air temperature, a significant improvement of the drying quality specifically for items made of plastics material is possible here. In particular, the drying time can thus also be considerably reduced in some circumstances. This is a key factor, in particular in the case of commercial washing.

(27) A second method step of the method according to the invention constitutes the desorption phase, during which the dry material of the sorption unit 41 is heated and air is guided from the treatment chamber 2 through the sorption unit 41 having the heated dry material. In so doing, moisture is desorbed from the dry material and at least some of the thermal energy introduced previously into the dry material as well as at least some of the moisture desorbed from the dry material is discharged from the sorption unit 41 in the form of water vapor with the aid of the airflow guided through the sorption unit 41. The water vapor produced here can be used for example to steam clean the items during the final rinse phase. In this regard, it is preferable if the second method step, that is to say the desorption phase, takes place at least partly during the final rinse phase in order to be able to use the water vapor produced during the desorption process for further cleaning of the items to be washed.

(28) It should be noted at this juncture that the quantity of moisture in the dry material of the sorption unit 41 can be established continuously or at predefinable times or events during the adsorption phase and/or the desorption phase. This is achieved in particular by a sensor unit, which for example measures the weight of the dry material, the duration of the desorption phase, the moisture content, or the temperature of the air at the air outlet of the drying device. The sensor unit (not illustrated) together with the program control unit can therefore be used to initiate the different program sequences on the basis of the moisture content of the dry material.

(29) It is also preferred if the adsorption phase requires 30 sec. to 5 min., preferably 1 min. to 3 min. By contrast, the desorption phase may take place within 5 sec. to 5 min., preferably 20 sec. to 3 min., and more preferably 1 min. to 2 min.

(30) The invention is not limited to the embodiments of a warewasher according to the invention illustrated in the figures, but is also provided from an overview of all features disclosed herein. In particular, the invention can also be applied equivalently to the technical field of tumble dryers. It should also be mentioned that the drying device 40 is not limited to having an individual fan 44 and also an individual sorption unit 41, but can by all means comprise two or more of these components. As has already been mentioned above, the drying device 40 may also for example have a heat exchanger (not illustrated), which serves for further reduction of the energy consumption.

LIST OF REFERENCE SIGNS

(31) 1 warewasher 2 treatment chamber 3 washing water 4 discharge 5 draining pump 11a, 11b washing jets 12 washing tank 13 washing pump 14 rinsing pump 15a, 15b rinsing jets 16 washing liquid line system 17 rinsing liquid line system 22 boiler 30 fresh water feed line 39 steam generator 40 drying unit 40a air inlet 40b air outlet 41 sorption unit 42 inlet line 43 outlet line 44 fan 45 heating unit 46 steam outlet 46a steam line 47 heater 48 level sensor 49 valve 50a first splash protection apparatus 50b second splash protection apparatus 51 first air distributor 52 second air distributor