Drying and gas or vapor contact with solids – Apparatus – For diverse operations on treated material
Reexamination Certificate
1998-07-10
2001-01-09
Gravini, Steve (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
For diverse operations on treated material
C034S068000, C034S069000, C034S079000, C034S084000, C034S595000
Reexamination Certificate
active
06170166
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and apparatus for venting gaseous, vaporous and airborne particulate material from, and cooling the inside, of processing equipment or machinery. In particular, the invention relates to the removal of heated air laden with water vapor from within commercial warewashing or dishwashing machines.
BACKGROUND OF THE INVENTION
Commercial automated dishwashers have been used for many years in a variety of different locales, wherever large amounts of cookware, silverware, dishware, glasses or other ware need to be cleaned and sanitized. Regardless of whether the dishwasher in question is a simple batch loading dishwasher or a complex multi-stage machine, there is an on-going problem with heated water vapor escaping the machine at the end of a cleaning program. This heat and humidity comes into direct contact with the kitchen personnel and generally reduces comfort of the kitchen environment. Commercial dishwashing machines can heat water or utilize very hot water from other sources, especially in the final rinse stage, to help ensure cleaning and sanitation. Current dishwashers are classified as either high temperature machines or as low temperature machines, based on final rinse water temperatures. The high temperature machines have a final rinse water temperature of at least about 180° F. while the low temperature machines have a final rinse water temperature of about 160° F. Such high temperatures are necessary to ensure adequate sanitization of the dishes or other ware being cleaned. The high temperature rinse allows for one-step sanitization whereas the low temperature rinse is typically accompanied by an additional chemical (chlorine, peracid, etc.) sanitization addition step. In either situation, hot ware and significant volumes of heated, highly humidified air are created in the dishwasher, particularly as a result of the final rinse, which is typically the hottest step in the dish or warewashing process.
Direct contact with hot, humid air can pose safety problems. The humidity causes significant safety problems for people who wear glasses and/or contact lenses. The hot, humid air can irritate people without eyewear as well. Significant amounts of heated water vapor are put into the room environment, straining air conditioning systems and generally creating discomfort for operators. Further, the dishes removed from the dishwasher can be at high temperature.
One way to address these difficulties concerns the use of vent hoods to capture the hot, highly humid air escaping from the dishwasher upon opening. A drawback to this method is that the hot, highly humid air contacts environmental air in the use locus and the hood removes only a portion. As a result, some heat and humidity is transferred to the immediate environment. While the hood will draw the hot, highly humid air up and away from the dishwasher, it may fail to completely protect the operator from contact with heat and humidity. In addition, hoods are large, noisy and expensive, wasting heat during winter months, and conditioned air in summer months. Further, such a system requires venting to the exterior of the building. Another way to address these problems concerns the use of electric exhaust fans to remove the heat and water vapor. Unfortunately, this is noisy, requires electricity and means to vent to the exterior of the building. In addition, this also requires a separate means to cool and condense the water vapor. EP 0 753 282 A1 deals with the problem of hot water vapor by cooling and condensing the steam released from the dishwasher. This is accomplished by directing the steam through a heat exchanger through which cold water is circulated. However, this device is limited to applications in which the wash chamber is sealed. Such a device would not work, for example, in a single-stage or multi-stage dishwashing machine open to the atmosphere. EP 0 721 762 A1 teaches the use of a fan to pull the steam into a condensation chamber in order to prevent the escape of moisture to the immediate environment. Of course, this method requires the use of a fan, which adds expense, complexity and noise to the dishwashing apparatus.
Therefore, a need remains for a simple, inexpensive and unobtrusive means for capturing the water vapor released from commercial dishwashers.
SUMMARY OF THE INVENTION
In brief, the invention involves the use of a water spray to create a zone of reduced pressure that can be used to remove heat and humidity and vent the interior of machines such as commercial dishwashers. Preferably, a water spray is used to form a zone of reduced pressure that draws the heat and humidity into the zone. In the zone the heat and humidity is captured and cooled. The hot, highly humid air created within commercial dishwashers can be removed rapidly and the ware can be cooled with ambient air. A cold water spray is used to create a pressure reduction which serves to draw in hot, highly humid air from the dishwasher. The high temperature water vapor cools and condenses on contact with the cold water jet or spray. The invention also serves to help vent the dishwasher and cool ware, as cold, fresh air is drawn into the dishwasher to replace the hot air drawn into the zone of reduced pressure.
Accordingly, the invention is found in a method of removing a heated atmosphere from a machine enclosure, the method comprising energizing a flow of water from a water spray within a housing to create a zone of reduced pressure in the housing in fluid communication between the machine interior and the housing, the reduced pressure introducing fresh atmosphere into the machine while removing the heated atmosphere.
Finally, the invention can also be found in a dishwashing machine, using water of elevated temperature, that can be cooled after completing one or more cycles, the machine comprising a machine enclosure comprising at least one inlet in fluid communication between the machine interior and the machine exterior, and extraction means comprising a housing comprising a water jet and at least one conduit in fluid communication between the machine enclosure interior and the housing, the spray nozzle providing a water spray effective to create a zone of reduced pressure within the housing for removing the hot humid atmosphere from within the machine enclosure while causing entry of fresh air into the machine through the inlet.
The extraction means comprises one or more air inlet means in fluid communication with both the inner compartment of the dishwasher and with a vertical structure comprising a cold water inlet in fluid communication with a spray nozzle. The spray nozzle is located at a horizontal level approximately equal to that of the air inlet means. The spray nozzle provides a high speed water spray suitable to create a venturi effect or a zone of reduced pressure that can serve to pull hot, moisture-laden air through the air inlet means; and an outlet means. For the purpose of this patent application, the term “extraction means” refers to a device that can use a difference in pressure to use the ambient atmospheric pressure to drive the atmosphere within a machine into the area of reduced pressure. The term “nozzle spray angle” connotes the angle, within the spray, bound by the perimeter of the spray as it exits from the nozzle opening. Such angles can typically range from about 5° up to about 180°.
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Britain Kent R.
Davidson Glen W.
Johansen Scott A.
Monsrud Lee J.
Ecolab Inc.
Gravini Steve
Merchant & Gould P.C.
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