Drying and gas or vapor contact with solids – Process – Gas or vapor contact with treated material
Reexamination Certificate
1998-02-10
2001-03-20
Wilson, Pamela (Department: 3749)
Drying and gas or vapor contact with solids
Process
Gas or vapor contact with treated material
C034S512000, C034S068000, C034S093000, C034S210000, C126S629000, C126S704000
Reexamination Certificate
active
06202321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention most generally relates to methods and apparatus for drying coffee beans and other green crops or coarse granular bulk materials composed of beans, seeds, pods, or grains of relatively large and uniform size, to reduce the moisture content. Most particularly, it relates to convective airflow drying systems, especially solar powered system, and removable, internally ventilated containers for handling the bulk materials being dried.
2. Background
The art of harvesting and processing coffee beans from tree-borne cherries to the green coffee bean of commerce consists of two principle methods, the “dry” method and the “wet” method. Either method must result in moisture content equivalent to one third or more of the bean's weight being removed, to produce a commercial product.
The dry method is the more ancient and rudimentary. The cherries are hand-picked all in one picking, washed, and sun-dried on drying ground or concrete slabs in thin layers, usually for a period of two to three weeks. The beans ferment during the process, and are turned several times a day to promote even drying. They are covered at night to protect them from moisture.
In the wet method, only the ripe cherries are picked in any one picking of a tree. It may take three to five sequential pickings in a season over the time it takes between the earliest and the latest cherries to ripen. After the cherries are washed, the outside fruit pulp is removed by machines and the berries are then placed into large concrete tanks to ferment for twelve to twenty-four hours, then poured into concrete sluiceways or washing machines to be thoroughly washed in constantly running water. Then they are dried in much the same way as in the dry method, except that the drying time is shorter. These beans are then processed through hulling machines to remove the remaining layers of skin.
Problems with either method of this art include the inefficient, labor-intensive and lengthy sun-drying time of beans on concrete slabs or the use of other manual, passive solar methods and devices. There are many patents that describe related technologies and devices. Various fuel-fired dryer systems have been used to try to accelerate the drying time and prevent the mold problems. These alternatives add expense and complexity to an otherwise simple process. Failing to safeguard the beans from excess moisture, in particular the formation of mold during the drying process is crucial as the value of the crop drops dramatically if mold occurs. Overdrying can also occur using accelerated methods; this also affects the quality and value of the crop.
The requirements for loading and unloading the crop into and out of small, stand alone, solar dryer systems is burdensome. The passive solar drying time is always too long; leaving the crop exposed to potential downturns in weather conditions.
SUMMARY OF THE INVENTION
The invention in it's simplest form is a solar powered dryer system for coarse granular bulk materials such as whole coffee beans, coca beans, and various grains, where a substantial degree of moisture must be removed from the bean, seed, pod or individual grains, as part of the processing of the material to make it useful. The cycle of loading and unloading of the bulk materials into and out of multiple small solar dryer systems can be accomodated by use of removable containers, and the efficiency of the systems is improved if the airflow is directed through the container and the bulk materials it holds. The invention is adaptable to utilize both convective solar heated airflow and direct solar radiation of the subject materials.
The principle functional components of a dryer system of the invention are an airflow generator, a removable, ventilated container for the materials, a means for receiving and supporting the removable container within the dryer system in such a way as to constrain air flow to flowing through the container.
It is characteristic of passive solar dryers that airflow is more limited than heat, by the relatively low differential pressure that can be generated in low cost, pratical solar dryers, and that it takes many hours or days to affect a significant reduction in moisture levels in the passive solar drying of most crops. The relative amount of dry airflow in low airflow dryer systems has been demonstrated to be the more significant factor to its utility and efficiency. It is therefore important to configure the dryer for maximum differential pressure, and maximum exposure of the materials to the dry air flow, while retaining a low cost structure and a simple bulk container handling system.
The removable container aspect of the invention has an open top and ventilated bottom and/or sidewall surface and is configured with air permeable airflow interior wall sections dividing the material into relatively thin vertical layers, or with columnar structures defining vertical air passageways with air permeable walls being distributed throughout the materials being dried. The container, when installed, divides the dryer plenum into upper and lower chambers. The relatively dry, outside air is heated and pushed by a convective generator into the dryer's lower chamber, spreads over the bottom of the container and rises through the air passages in the container, leaching out the excess moisture in the materials and carrying it to the upper region of the plenum, where it is then exhausted.
It is an object of the invention to have a convective airflow dryer system with a materials container for drying coffee beans and other such crops and materials, with interior airways extending through the container through which the convective airflow of the system can be directed, where the airway walls are gas permeable and will freely admit, flow and transfer air, including moisture ladened air from the coffee beans or other material being dried, into the airways and out of the container, and where the container is easy to fill, insert, remove, empty, refill and reuse.
It is another object of the invention to provide such a container and system where the container is mounted on wheels or rails, to faciliate the engagement and disengagement of the container with the stationary part of the dryer system.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein I have shown and described only a preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by me on carrying out my invention.
REFERENCES:
patent: 278199 (1883-05-01), Sweeny
patent: 1556865 (1925-10-01), Müller
patent: 4045880 (1977-09-01), Steffen
patent: 4099338 (1978-07-01), Mullin
patent: 4122828 (1978-10-01), DiPeri
patent: 4263721 (1981-04-01), Danford
patent: 4391046 (1983-07-01), Pietraschke
patent: 4490926 (1985-01-01), Stokes
patent: 4501074 (1985-02-01), O'Hare
patent: 5001846 (1991-03-01), Andrassy
patent: 5584127 (1996-12-01), Sutherland
patent: 5960560 (1999-10-01), Stoll
Asmus Scott J.
Maine Vernon C.
Wilson Pamela
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