Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-08-31
2001-05-22
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C034S369000, C034S588000, C392S493000, C432S132000
Reexamination Certificate
active
06236022
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the design and operation of a hot shelf tower dryer for a cotton gin. More specifically, the present invention concerns the placement of electrical heating elements at specific locations within a hot shelf dryer to augment the drying power of such a dryer.
2. Description of the Prior Art
Since it was invented by Eli Whitney more than a century ago, the cotton gin has remained the primary tool used to remove extraneous material, more commonly known as “trash,” from newly-picked cotton. The “trash” removed typically includes seeds and other parts of the cotton plant that are collected together with the raw cotton when it is harvested. This “trash” must be separated from the cotton fibers before the fibers can be processed into thread and, ultimately, into fabric.
Cotton, however, is not ginned immediately after it is picked. Instead, among other pre-ginning processes, high moisture seed cotton is first partially dried in various types of apparatus known as a hot shelf tower dryer or a seed cotton dryer of some other type. The hot shelf tower dryer is a direct application of the knowledge that cotton is more easily ginned if a significant portion of the moisture contained in the cotton is first removed.
To dry cotton, the conventional hot shelf tower dryer includes a vertical tower casing, with substantially parallel shelf partitions. These shelf partitions alternately extend from one end wall of the tower casing to a location near the opposite end wall. So configured, the shelf partitions define a continuous zig-zag passage through the tower casing that guarantees a sufficient amount of drying by ensuring that the cotton remains in the dryer for a selected period of time at a desired temperature or range of temperatures.
In the conventional seed cotton dryer, cotton and heated air initially enter the hot shelf tower dryer through an inlet, located proximate to the top of the tower casing. The heated air carries the cotton through the convoluted path in the dryer to the outlet. As the cotton, which may have an initial moisture content of between about 15% to 20%, passes through the dryer, moisture is progressively driven from the cotton until the cotton exits the dryer with a moisture content of between about 11% to 16%. As many as three or four subsequent drying stages are needed to bring the cotton to a desired moisture content of between about 5½% to 6½%.
The heated air that carries the cotton through the dryer is inadequate, by itself, to dry the cotton sufficiently before it exits the dryer. This is because the initial exposure of wet cotton to the heated air results in a rapid evaporation of moisture from the seed cotton that robs the heated air of a significant portion of its thermal drying energy. As a result, the air becomes cooler. To compensate for the loss of drying energy associated with a reduced temperature, conventional hot shelf tower dryers include heated air ducts inside the shelves over which the seed cotton travels, as depicted in
FIGS. 2 and 3
. The heated air provided to these ducts or chambers supplies additional heat to the air in the tower casing to augment the drying process.
Both U.S. Pat. No. 4,031,593 and U.S. Pat. No. 5,233,764 describe hot shelf tower driers with heated shelves that assist in drying seed cotton. As these disclosures provide, the shelves are heated by hot air circulated in the hollow interior chambers of the shelves. A push fan, which receives heated air from a remote heater, directs the heated air to and circulates this heated air within the shelf chambers.
In the conventional dryer design, because the heated air is generated remotely, there is a heat loss associated with the conveyance of the hot air to the shelf chambers. Depending upon the distance that the heated air must travel, this heat loss may be significant. The heater, as a result, must compensate for this temperature drop and, consequently, must increase the temperature of the heated air to a point higher than that required by the individual shelf chambers.
Typically, to attain a temperature of approximately 400° F. in a chamber proximate to the inlet, a conventional heater, positioned beneath the outlet, may require an output temperature of approximately 900° F. As expected, to attain such an increased level of heat requires the addition of a significant amount of energy to the heater.
Traditionally, natural gases or other fossil fuels have been used to heat the air for a seed cotton dryer. These natural resources, however, do not enjoy an unlimited surplus. As such, their consumption in providing the additional power to the heater involves both monetary as well as environmental waste.
In addition, these resources entail a fuel burning process that produces numerous pollutants in the form of gaseous emissions, such as nitrous oxide (NO
x
), the production of which has become increasingly restricted in an increasingly environmentally-conscious marketplace. The state of California is one such area where stringent regulations regarding fuel emissions have been implemented.
In this increasingly environmentally-conscious marketplace, the use of conventional burners to supply heat to the hot shelf tower dryer has become increasingly less desirable. The inability of the traditional hot shelf tower dryer and any other drying system to incorporate features that continue to provide the appropriate amount of cotton drying while reducing the amount of fuel consumed as well as the amount of fuel emissions produced has created a specific need for alternative techniques for mitigating temperature loss.
The present invention addresses these concerns by providing an apparatus that is practical and adaptable in both its design and application.
SUMMARY OF THE INVENTION
The advantages and purpose of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purpose of the invention will be realized and attained through the elements and combinations of elements particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the hot shelf tower dryer of the present invention includes a casing having opposed end walls, an inlet and an outlet. The casing further includes a plurality of shelves disposed in generally parallel, spaced relation between the inlet and the outlet. Each shelf alternately extends from one end wall to a location proximate the opposing end wall to define a convoluted passage between the inlet and the outlet. The tower casing receives seed cotton through the inlet and conveys the seed cotton through the passage which leads to the outlet. At least one shelf includes a chamber. Disposed in the chamber is at least one electrical heating element, the power supply to which is regulated by a control system.
In another aspect of the present invention, the hot shelf tower dryer includes seven shelves, each provided with a chamber. Each of the seven chambers includes a floor. Eighteen electrical heating elements are disposed on the floor of each of the seven chambers. The power supplied to the electrical heating elements is regulated by a control system so that the one hundred twenty-six electrical heating elements dispersed throughout the seven chambers produce a total output of approximately 1.5 million BTU, or equivalently 439 KW. This output from the electrical heating elements corresponds to an air temperature range in each chamber of approximately 150° to 400° F. The heat transferred from the chambers helps to maintain an air temperature in a range of about 150° F. to about 250° F. throughout the cotton passage of the tower casing.
In yet another aspect of the invention, each of the seven chambers includes a ceiling in addition to the floor. Eighteen electrical heating elements are disposed on the floor as well as the ceiling of each of the
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Fuqua Shawntina
Walberg Teresa
LandOfFree
Hot shelf tower dryer for a cotton gin using electrical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hot shelf tower dryer for a cotton gin using electrical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hot shelf tower dryer for a cotton gin using electrical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2490123