Conveyor dishwasher and method for operating a conveyor dishwasher

Abstract

A conveyor dishwasher ( 2 ) includes a final rinse zone ( 18 ) and at least one wash zone ( 12, 14, 16, 18 ) and also a conveyor apparatus for conveying washware through the treatment zones of the conveyor dishwasher ( 2 ), wherein the at least one wash zone ( 12, 14, 16, 18 ) has an associated wash tank ( 32, 34, 36 ) in which at least a portion of the wash liquid which is sprayed in the at least one wash zone ( 12, 14, 16, 18 ) is collected. The conveyor dishwasher ( 2 ) also has a wastewater pump ( 61 ) for supplying wash liquid, which is produced as wastewater during operation of the conveyor dishwasher ( 2 ), to a heat exchanger device ( 60 ) in which at least a portion of the thermal energy of the supplied wash liquid is transferred to the final rinse liquid which is to be sprayed in the final rinse zone ( 18 ).

1 . Conveyor dishwasher ( 2 ) having a final rinse zone ( 18 ) and at least one wash zone ( 12 ,  14 ,  16 ,  18 ) and also a conveyor apparatus for conveying washware through the treatment zones of the conveyor dishwasher ( 2 ), wherein the at least one wash zone ( 12 ,  14 ,  16 ,  18 ) has an associated wash tank ( 32 ,  34 ,  36 ) in which at least a portion of the wash liquid which is sprayed in the at least one wash zone ( 12 ,  14 ,  16 ,  18 ) is collected, wherein the conveyor dishwasher ( 2 ) has a wash system which is associated with the at least one wash zone ( 12 ,  14 ,  16 ,  18 ) and has at least one wash pump ( 33 ,  35 ,  45 ) and wash nozzles ( 26 ,  28 ,  30 ), wherein wash liquid from the wash tank ( 32 ,  34 ,  36 ) can be supplied to the wash nozzles ( 26 ,  28 ,  30 ) with the aid of the at least one wash pump ( 33 ,  35 ,  45 ), and wherein the wash liquid which is sprayed in the at least one wash zone ( 12 ,  14 ,  16 ,  18 ) by the wash nozzles ( 26 ,  28 ,  30 ) at least partially flows back into the wash tank ( 32 ,  34 ,  36 ) again due to gravity, characterized in that
 the conveyor dishwasher ( 2 ) has a wastewater pump ( 61 ) for supplying wash liquid, which is produced as wastewater during operation of the conveyor dishwasher ( 2 ), as required to a heat exchanger device ( 60 ) in which at least a portion of the thermal energy of the supplied wash liquid is transferred to the final rinse liquid which is to be sprayed in the final rinse zone ( 18 ), and in that the conveyor dishwasher ( 2 ) has an auxiliary tank ( 67 ) which forms a flow connection with the wash tank ( 32 ,  34 ,  36 ) in particular by means of an overflow ( 68 ) or by means of a bypass line, wherein the intake end of the wastewater pump ( 61 ) forms a direct flow connection with the auxiliary tank ( 67 ).   
     
     
         2 . Conveyor dishwasher ( 2 ) according to  claim 1 , wherein the conveyor dishwasher ( 2 ) has a control device ( 50 ) which is designed to drive the wastewater pump ( 61 ) depending on a quantity of final rinse liquid which is currently required per unit time and/or a quantity of wastewater which is produced during operation of the conveyor dishwasher ( 2 ) and/or depending on a liquid level of the auxiliary tank, or on a liquid level in at least one wash tank ( 32 ,  34 ,  36 ) of the conveyor dishwasher and/or depending on a predefined event and/or depending on an operating cycle and/or operating state of the conveyor dishwasher ( 2 ). 
     
     
         3 . Conveyor dishwasher ( 2 ) according to  claim 1 , wherein the conveyor dishwasher ( 2 ) has a control device ( 50 ) which is designed to switch off the wastewater pump ( 61 ) automatically when the liquid level in the wash tank ( 32 ,  34 ,  36 ) falls below a predefined or predefinable first level, and to switch on the wastewater pump ( 61 ) again automatically as soon as the liquid level in the wash tank ( 32 ,  34 ,  36 ) exceeds a predefined or predefinable second level, wherein the first level corresponds to the second level. 
     
     
         4 . Conveyor dishwasher ( 2 ) according to  claim 2 , wherein the control device ( 50 ) is designed to initiate, as required, hot water treatment, which is independent of the heat exchanger device ( 60 ), of the final rinse liquid which is to be sprayed in the final rinse zone ( 18 ), specifically in particular when:
 i) the thermal energy which is transferred to the final rinse liquid, which is to be sprayed in the final rinse zone ( 18 ), in the heat exchanger device ( 60 ) is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature; and/or   ii) no wash liquid is supplied to the heat exchanger device ( 60 ); and/or   iii) the quantity of wash liquid which is supplied to the heat exchanger device ( 60 ) per unit time is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature.   
     
     
         5 . Conveyor dishwasher ( 2 ) according to  claim 2 , wherein the conveyor dishwasher ( 2 ) has a boiler ( 9 ,  65 ) for heating, as required, the final rinse liquid which is to be sprayed in the final rinse zone ( 18 ), wherein the control device ( 50 ) is designed to activate the boiler ( 9 ,  65 ) when:
 i) the thermal energy which is transferred to the final rinse liquid, which is to be sprayed in the final rinse zone ( 18 ), in the heat exchanger device ( 60 ) is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature; and/or   ii) no wash liquid is supplied to the heat exchanger device ( 60 ); and/or   iii) the quantity of wash liquid which is supplied to the heat exchanger device ( 60 ) per unit time is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature.   
     
     
         6 . Conveyor dishwasher ( 2 ) according to  claim 5 , wherein the boiler ( 9 ,  65 ) is designed to heat up the final rinse liquid which is to be sprayed in the final rinse zone ( 18 ) to a predefined or predefinable minimum temperature using electrical energy, steam, a heat pump, gas or hot water. 
     
     
         7 . Conveyor dishwasher ( 2 ) according to  claim 2 , wherein an external boiler is provided, the conveyor dishwasher ( 2 ) forming or being able to form a flow connection with the said external boiler by means of a hot water connection ( 66 ), for supplying, as required, hot water as the final rinse liquid which is to be sprayed in the final rinse zone ( 18 ), wherein the control device ( 50 ) is designed to activate the hot water connection ( 66 ) when:
 i) the thermal energy which is transferred to the final rinse liquid, which is to be sprayed in the final rinse zone ( 18 ), in the heat exchanger device ( 60 ) is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature; and/or   ii) no wash liquid is supplied to the heat exchanger device ( 60 ); and/or   iii) the quantity of wash liquid which is supplied to the heat exchanger device ( 60 ) per unit time is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature.   
     
     
         8 . Conveyor dishwasher ( 2 ) according to  claim 1 , wherein the wash tank ( 32 ,  34 ,  36 ) has a capacity of 20 to 200 litres, and the auxiliary tank ( 67 ) has a capacity of 10 to 50 litres. 
     
     
         9 . Conveyor dishwasher ( 2 ) according to  claim 1 , wherein the conveyor dishwasher ( 2 ) further has a wastewater line ( 62 ) which forms or is able to form a flow connection with a wastewater system ( 63 ) and by means of which the wash liquid is discharged after the wash liquid has first passed the heat exchanger device ( 60 ). 
     
     
         10 . Conveyor dishwasher ( 2 ) according to  claim 1 , wherein the heat exchanger device ( 60 ) has at least one counterflow heat exchanger. 
     
     
         11 . Method for operating a conveyor dishwasher ( 2 ), in particular a conveyor dishwasher ( 2 ) according to  claim 1 , wherein at least a portion of the wash liquid which is produced as wastewater is at least temporarily supplied to a heat exchanger device ( 60 ) in which at least a portion of the thermal energy of the supplied wash liquid is transferred to the final rinse liquid which is to be sprayed in a final rinse zone ( 18 ) of the conveyor dishwasher ( 2 ). 
     
     
         12 . Method according to  claim 11 , wherein the wash liquid is supplied as wastewater to a wastewater system ( 63 ) after passing the heat exchanger device ( 60 ). 
     
     
         13 . Method according to  claim 11 , wherein the wash liquid is supplied to the heat exchanger device ( 60 ) cyclically and/or depending on a liquid level in the wash tank ( 32 ,  34 ,  36 ). 
     
     
         14 . Method according to  claim 11 , wherein, when no wash liquid is supplied to the heat exchanger device ( 60 ) and/or when the thermal energy which is transferred to the quantity of final rinse liquid, which is to be sprayed in the final rinse zone ( 18 ), in the heat exchanger device ( 60 ) is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature, a boiler ( 9 ,  65 ) which operates independently of the heat exchanger device ( 60 ) is activated. 
     
     
         15 . A conveyor dishwasher having multiple treatments zones including a final rinse zone and at least one wash zone, a conveyor apparatus for conveying washware through the treatment zones, wherein the at least one wash zone has an associated wash tank in which at least a portion of the wash liquid which is sprayed in the at least one wash zone is collected, wherein a wash system is associated with the at least one wash zone and has at least one wash pump and wash nozzles, wherein wash liquid from the wash tank can be supplied to the wash nozzles via operation of the at least one wash pump, and wherein the wash liquid which is sprayed in the at least one wash zone by the wash nozzles at least partially flows back into the wash tank again due to gravity, 
       wherein
 the conveyor dishwasher has a wastewater pump for supplying wash liquid, which is produced as wastewater during operation of the conveyor dishwasher, to a heat exchanger device in which at least a portion of the thermal energy of the supplied wash liquid is transferred to the final rinse liquid which is to be sprayed in the final rinse zone, wherein the conveyor dishwasher has an auxiliary tank with an overflow connection or bypass line connection with the wash tank, wherein the intake side of the wastewater pump is connected to receive flow from the auxiliary tank. 
 
     
     
         16 . The conveyor dishwasher according to  claim 15 , wherein the conveyor dishwasher has a control device which is configured to selective drive the wastewater pump depending on a quantity of final rinse liquid which is currently required per unit time and/or a quantity of wastewater which is produced during operation of the conveyor dishwasher and/or depending on a liquid level of the auxiliary tank, or on a liquid level in at least one wash tank of the conveyor dishwasher and/or depending on a predefined event and/or depending on an operating cycle and/or operating state of the conveyor dishwasher. 
     
     
         17 . The conveyor dishwasher according to  claim 15 , wherein the conveyor dishwasher has a control device which is configured to automatically switch off the wastewater pump when the liquid level in the wash tank falls below a predefined or predefinable first level, and to automatically switch on the wastewater pump again as soon as the liquid level in the wash tank exceeds a predefined or predefinable second level. 
     
     
         18 . The conveyor dishwasher according to  claim 17 , wherein the control device is configured to selectively initiate hot water treatment, which is independent of the heat exchanger device, of the final rinse liquid which is to be sprayed in the final rinse zone, specifically in particular when:
 i) the thermal energy which is transferred to the final rinse liquid in the heat exchanger device is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature; and/or   ii) no wash liquid is supplied to the heat exchanger device; and/or   iii) the quantity of wash liquid which is supplied to the heat exchanger device per unit time is not sufficient to heat the final rinse liquid to a predefined or predefinable minimum temperature.   
     
     
         19 . The conveyor dishwasher according to  claim 18 , wherein the conveyor dishwasher has a boiler for selectively heating the final rinse liquid after the final rinse liquid passes through the heat exchanger, and the control device operates the boiler for purpose of the selective hot water treatment. 
     
     
         20 . The conveyor dishwasher according to  claim 19 , wherein the boiler is designed to heat up the final rinse liquid to a predefined or predefinable minimum temperature using electrical energy, steam, a heat pump, gas or hot water.