Thursday, September 7, 2017

Late Summer Updates

Cotton is planted, and on a still night if you listen close enough, You can hear it growing.

Does this dryer look familar?

Continental Gin Company Counterflow Dryer 1950's
Note Cylinders at Bottom.

There seems to be a renaissance for this type of dryer, followed by large amounts of cylinder cleaner arrangements. This is a little history of this type of drying and why it ultimately faded. This information is taken from "Ginning Cotton, An Entrepreneur's Story," By A.L. Vandergriff. Pages 209-210.

Continental Introduced a counterflow dryer in the 1950's. It  was a unit consisting of a vertical box with spiked cylinders mounted inside in a vertical row, along the centerline of the box or chamber.  Adjacent to the cylinders on each side were long metal strips mounted on the wall of the box, spaced so that air could flow between them.  The cotton entered to top of the box by gravity onto the first cylinder, which knocked it onto the metal strips. These metal strips were sloped downward so the cotton could slide down them to the next cylinder. This process was repeated from one cylinder to the next. I believe there were four of these cylinders in the stack. Heated air entered the bottom of the box and traveled upward against the flow of cotton, thus the name counterflow.  Once I began increasing the capacity of the plants, it became necessary to split the flow and in doing this I added Tower Dryers, placing the counterflow dryers in series and following the Towers. This was done to primarily make use of the three cylinder cleaner under the counterflow dryers.  Currently, it is important to note deficiencies with the counterflow concept here and why and actual dryer had to be added prior to.  These dryers were never efficient. The fiber to fiber exposure to heated air was not as good as that in the Tower Dryers.  It seems that none of the drying efforts that tumbled cotton in bulk were efficient.  

We at Vandergriff American like to expose the cotton to drying and conditioning before getting into any type of cylinder arrangement, and we like to keep fiber exposure to any mechanical action (cylinders) to a minimum.  The action in our Jet Dryer requires no cylinders or any type of mechanical action. We create what we call a natural dynamic.  The cotton is conveyed to the top of the dryer in a  single stream and hits the top of our Jet, which is cylindrical. It then fans out in a 360 degree arc and begins its descent down the sides engaging the upspream flow of cotton. This dynamic creates turbulence and a swirling action that begins to single lock the fibers to allow warm air to flow through, and trash to begin to separate out.  It then exits out to the inclines or cylinder arrangement most gins currently have.  We get a nice even flow and even bat that allows the cotton to spread nicely across all the cylinders.  There is no need to add a horizontal cleaner arrangment with this. You can use what you have. If you are installing Jets in a new plant, the horizontal cleaner will work fine if this is the route you choose to go. There is mimium static drop with our system compared to a large number of cylinders that the cotton would be exposed to with a counter-flow/vertical flow type system. Remember, these systems start the drying process with cylinders involved.  All are in agreement that it is not desirable from a fiber quality point of view to let cotton be exposed to lots of cylinder's and too much aggressive mechanical action to dry and clean. Also note that with these counter/flow, vertical flow type "dryers," followed by a large number of cylinders, there is a real danger of roping and trash being embedded if this 1950's approach does not get the moisture content of the cotton down enough prior to entering the cylinders. Big risk here.  How much do you want to "slow down," on wet cotton to keep fiber quality up?  Our Jet's will work with your existing 8', 10' and even 12" cleaners in both stages of your operation. So, what you get with our system is a good drying dynamic without excessive cylinder exposure. It preps and conditions the cotton nicely and allows your existing cylinder cleaner arrangement to work more efficiently in terms of fine trash removal.  

"Don't let your cotton fiber be exposed to an excessive amount of cylinders, and then be run through 2 stages of "Shredders," (lint cleaners) before getting to the press.  The Fiber and the mills will appreciate you.


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