Gas and liquid contact apparatus – With external supply or removal of heat – Processes
Reexamination Certificate
2000-03-24
2002-06-18
Bushey, C. Scott (Department: 1724)
Gas and liquid contact apparatus
With external supply or removal of heat
Processes
C261S028000, C261S069100, C261S078200, C261S115000, C261S131000, C261SDIG001
Reexamination Certificate
active
06406006
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to systems and methods for extending the life of fresh and/or perishable food products using automated humidification systems. The invention relates particularly to the use of automated humidification systems that release water vapor or droplets into various environments for storage of fresh or perishable products.
BACKGROUND OF THE INVENTION
To maintain the freshness and desirable appearance of fresh products, such as perishable foods displayed in a merchandising case or display counter in a supermarket, or produce or plant materials housed in a storage facility, the produce must be kept in an environment that is cool and moist. The amount of moisture must be carefully regulated to maintain the quality and storage-life of various perishable products. For example, dehydration of fresh produce results in spoilage, an unattractive product appearance and reduced salability. Too much moisture may result in excess water retention, producing an undesirable appearance and increased susceptibility of the products to bacterial or fungal growth.
Several systems have been developed for hydrating fresh food items. Automated fresh produce hydration systems are described, for example, in the following U.S. Patents, which are incorporated herein by reference in their entireties: U.S. Pat. Nos. 4,808,303; 5,470,970; and 5,651,502. These patents describe various approaches to hydrating fresh food. In all of them, water is conveyed to a plurality of spray or nozzle heads designed to deliver moisture in the form of a mist or a fog or vapor to food items displayed or stored below the spray heads. These systems utilize a regulator, solenoid valve and pressurization tank to adjust and maintain the water pressure.
Many conventional humidification systems utilize air pressure to atomize water, forming a vapor which is then distributed into the environment to regulate the relative humidity. To atomize water, conventional systems employ air pressure in combination with pressurized water to generate a pressure head sufficient to force the air/water mixture through the spray head or nozzle assembly to achieve a very fine water vapor. The water pressure determines the volume of water dispersed into the environment through the spray heads. The interval and duration of water vapor release is regulated through a timer, sensor or control device that activates a compressor, which pressurizes the system as described above.
An inherent problem with humidification and misting systems is the “streaming” of water from the spray heads or nozzles at the end of a pressurization and water atomization cycle, which is due to residual pressure in the water line. This streaming of water is very undesirable because excess water adversely affects the quality and storage life of the products immediately below. To compound the problem, the greater the water pressure of the system, as required for a large storage facility, the greater the streaming effect. To remedy this problem, conventional systems reduce the water pressure down to a range of 2 to 5 psi by means of a regulator and solenoid valve system at the end of a pressurization cycle. Additionally or alternatively, these systems often require a bladder tank on the air line to serve as a capture reservoir for surplus air pressure once the compressor has shut off at the end of a cycle. By reducing the water and/or air pressure, the system pressure drops accordingly, alleviating the force that causes the water to release or stream from the spray heads.
Furthermore, to achieve proper atomization of water, conventional systems require a carefully balanced ratio of air to water pressure, which must be tailored to the specific application. For example, a seafood display case in a supermarket requires low air and water pressure to deliver a small volume of water vapor and maintain a predetermined relative humidity, whereas a large produce storage facility requires higher air and water pressure to deliver a large volume of water and maintain a desired relative humidity. In all instances, the volume of water vapor required to achieve the desired relative humidity for each particular application requires a careful balancing of the air to water pressure ratio. This individualized “tuning” of the system is required to meet the specific requirements of the particular environment in which the humidification system is employed. These systems have many disadvantages.
Another deficiency of conventional humidification and misting systems, specifically systems employed in large storage facilities, is blockage of the misting nozzles, water and air lines due to freezing. In general, the majority of the systems installed in storage facilities are for cold storage, which typically require ambient air temperatures of 34° F. To achieve and sustain a uniform 34° F. ambient temperature, it is common for the nozzle assemblies and the air and water lines to be exposed to temperatures ranging from 20-25° F. due to their proximity to refrigeration systems. As a result, water freezes in atomization nozzles and water lines, as well as water accumulated in air lines through condensation. The present invention remedies this problem by providing a system incorporating a heated conduit assembly. The heated conduit assembly is incorporated into humidification systems immediately upstream of the atomization nozzles and maintains the temperature of the atomization nozzles and associated air and water lines above the freezing point to prevent blockage of the system.
The present invention is therefore directed to an automated humidification system that is more effective and efficient, less expensive to manufacture and install, and more flexible in its application than automated humidification systems currently used by industry. These features will be further discussed herein and represent a significant advance in this field.
SUMMARY OF THE INVENTION
The present invention provides improved systems and methods for the hydration of environments in which perishable products are displayed and/or stored. Systems of the present invention are especially suitable for use in connection with the storage and display of fresh and/or perishable food items, including fresh fruits and vegetables, meat, seafood, dairy, tobacco and floral items. Notably, the inventive systems may be employed in various storage environments such as display cases, walk-in storage rooms, greenhouses and large-scale storage facilities, or other such environments.
A particular aspect of the present invention is directed towards systems, methods and
kits for providing consistent humidification while effectively eliminating the problem of “streaming.” Streaming or dripping, as used herein, is defined as water escaping from atomization nozzles at the end of a pressurization and atomization cycle. Streaming is effectively controlled by one or more drawback valves incorporated into automated humidification systems. At the end of a pressurization and atomization cycle, said drawback valve generates negative water pressure in associated water lines and components, thereby drawing the water head in a retrograde direction and holding said water head in place until the next pressurization cycle. Negative water pressure generated by drawback valve effectively prevents water streaming from atomization nozzle assemblies. Furthermore, residual air pressure in associated air distribution lines fully atomizes any residual water in associated water lines and components, thereby displacing any residual water that may be inclined to stream onto products below.
The present invention provides a more compact and self-contained system that utilizes fewer parts, and therefore is less expensive to manufacture. The present invention eliminates the traditional regulators, pressure tanks and solenoid valve assemblies required to control water-pressure, as well as bladder tanks and regulator valves for regulating air pressure, while more effectively controlling the problem of streaming.
Systems of the present invention are simp
Coyle James
Croydon Spencer
Dettling Charlie R.
Bushey C. Scott
Klaniecki James E.
Raytec Corporation
Speckman Ann W.
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