Lummus Gentle Ginning Overview

Ginning Overview

THE LUMMUS GENTLE GINNING SYSTEM

Lummus’ core business continues to be rooted in its line of cotton ginning machinery, known as the Lummus Gentle Ginning System. Whenever landmark ginning facilities around the world have been constructed through the years, they have all shared a common link – Lummus machinery. When proven reliability and performance matter most to a customer, Lummus is the name chosen over any other.

All Lummus gin machinery is designed to preserve and protect the cotton’s valuable fiber properties throughout the ginning process. The myriad of variables (cotton varieties, harvesting methods, ginning season length, daily/seasonal throughput, etc.) enforces the need for a source with extensive industry expertise – a company that knows and understands the details of cotton gin construction.

Background

A cotton ginning facility, typically referred to as a “cotton gin” or “ginnery,” is actually a processing plant composed of various machines, each with a specific function, arranged in sequence to unload raw seed cotton, condition it, separate the fiber (referred to as “lint”) from the seed, clean the lint, dispose of the seed and trash, and bale/package the lint. A gin plant should not be confused with a gin stand, which is the machine that physically separates the lint from the seed.

Early gin plants were fairly simple facilities, as the clean, dry, hand-picked cotton of the day required little conditioning or cleaning prior to the ginning process. However, as harvesting methods (hand snapping, mechanical picking, and mechanical stripping) produced more moisture and trash in the incoming seed cotton, additional machinery was required upstream (drying and precleaning) and downstream (lint cleaning) of the gin stand(s) to maximize the value of the final lint sample in the marketplace. Thus, the typical gin plant of today is vastly more complicated that the gin plants of fifty years ago. Adding to this complexity is the fact that ginning machinery capacities continue be pushed to new levels. This is a result of the worldwide ginning industry being in a constant state of consolidation to improve profitability, while maintaining the throughput capacity to process a world cotton crop that is relatively stable.

Process Flow

There are two major types of cotton grown in the world: Upland (fuzzy seed) and Extra-Long Staple (ELS) or Pima (slick seed). Upland cotton accounts for the vast majority of worldwide cotton acreage and is ginned using saw-type gin stands. Its end uses range from the lower count yarns used for producing denim to medium count yarns used in undergarments and general textiles. ELS cotton, ginned using roller-type gin stands, is a much smaller percentage of the world crop. ELS cotton’s longer staple length lends itself to the production of higher count yarns, which are used in fine shirtings, and upscale, premium textiles (sheets, towels, etc.) Lummus’ Gentle Ginning System offers machinery to handle both of these cotton types. Much of the machinery upstream from the actual ginning process is similar, while ginning and lint cleaning will vary substantially, based upon the variety being processed. Regardless, most modern gin plants will feature most, if not all of the following systems, in varying degrees of complexity:

  • Unloading
  • Drying and Precleaning
  • Distribution and Overflow
  • Feeding and Ginning
  • Lint Cleaning
  • Condensing and Moisture Restoration
  • Pressing and Bale Handling

Unloading System

The Unloading System is the means by which the incoming seed cotton is introduced into the gin plant. When seed cotton is transported to the gin plant in sacks, trailers, or trucks, Telescopes, use air suction to unload the seed cotton, convey it into an Unloading Separator, which separates the seed cotton from the conveying air stream.

For gin plants that process seed cotton modules, either a travelling-head or stationary-head Module Feeder is furnished. The Module Feeder uses high-speed spiked cylinders to pluck the locks of seed cotton from the compacted module, blending the seed cotton across the entire face of the module.

The Automatic Suction Control (or Storage Hopper) is the next machine in the system. This machine provides for a smooth flow of well-opened seed cotton into the first-stage drying system through the use of two variable-speed Feed Rollers and a Disperser Cylinder feeding a Vacuum Wheel (or rotary air lock). When a Module Feeder is furnished, the Automatic Suction Control is typically mounted beneath the Module Feeder Disperser head in a pit. If only telescopes are furnished, it mounts at floor level, beneath the Unloading Separator

Drying and Precleaning Systems

Based on the amount of moisture and trash in the incoming seed cotton, gin plants will typically be furnished with either one stage (for hand-picked cotton) or two stages (for machine-picked and machine-stripped cotton) of drying and precleaning machinery. Gas or Oil-Fired Burners provide heat for the drying/conveying air. Shelf-type Tower Dryers are sized and specified to provide for a prescribed ratio of heated air to seed cotton, so as to allow for maximum drying at reasonable air temperatures.

From the Tower Dryer, the seed cotton is conveyed via the heated air stream to the Inclined Hot Air Cleaner, which uses spiked cylinders to convey the seed cotton across grid-type racks, removing small trash and further opening the cotton. The Hot Air Cleaner also serves as the separation point for the seed cotton from the now moisture-laden and dirty air. Attached to the discharge hood of the Hot Air Cleaner is a Vacuum Wheel (or rotary air lock), which seals the Hot Air Cleaner from the subsequent machine(s) in the system.

The second cleaner in the first-stage precleaning system is an extractor-type cleaner, in which the seed cotton is fed via gravity onto channel saw-type extractor cylinders. These cleaners are designed to remove sticks, leaves, and heavier trash from the seed cotton, once it has been through at least one stage of drying. In machine-picked seed cotton regions, the extractor cleaner is typically a Lummus Little Giant Stick and Green Leaf Machine, while in machine-stripped areas, the Lummus Stripper and Ground Harvester (S&GH) Machine is usually furnished. In especially rough-harvested cotton regions, both an S&GH Machine and Little Giant Stick Machine will be mounted under the first-stage Hot Air Cleaner.
The second-stage drying system may feature a separate burner for its source of hot air, or it may borrow heat from a single, larger burner. Depending upon the level of incoming moisture, a gin plant may or may not feature a second-stage Tower Dryer. Often, conveying the seed cotton from the first-stage precleaning to the second-stage precleaning in a heated air stream (using conventional round piping) supplies more than adequate conditioning for the cotton.

The second-stage precleaning system (or first-stage system for hand-picked regions) consists of an Inclined Hot Air Cleaner alone or a Hot Air Cleaner mounted over a TrashMaster Cleaner. The Hot Air Cleaner serves the identical purpose as in a first-stage system, while the TrashMaster Cleaner (a specially-designed, gravity-fed spiked cylinder machine) removes bark, sticks, stems, large leaves and grass through the use wider-spaced grid rods to allow a certain amount of good seed cotton to be thrown off with the fibrous-type trash. This good seed cotton is then reclaimed and returned to the seed cotton flow by the TrashMaster’s extractor-type reclaimer section before it is discharged into the trash line.

Distribution and Overflow System

The Conveyor Distributor is a screw-type conveyor, mounted in a specially-designed trough, which receives the seed cotton from the precleaning machinery mounted above it and conveys it, distributing it into hoppers mounted above the extractor feeders. Any excess seed cotton that carries past the feeder hoppers is collected in an Automatic Overflow Hopper, which feeds it into an air stream that returns the cotton to an Overflow Separator. The Overflow Separator is mounted so as to re-introduce the seed cotton to the Conveyor Distributor, thus completing the live overflow cycle.

Feeding and Ginning System

We now reach the heart of the gin plant, whether it process Upland or ELS cotton. For Upland cotton, a gin plant will be furnished with from one to usually no more than five extractor feeder/saw-type gin stand machinery stacks. Lummus’ current saw gins are the Imperial III line, available in either 170-Saw (96” wide) or 116-Saw (66” wide) models. Each Imperial III gin stand is fed by a matching Model 700 II Feeder. The 700 II Feeder is the final precleaner in the gin plant, and it also serves to single-lock the seed cotton, which facilitates efficient, high-capacity ginning. The Imperial III Gins offer superior capacity for their respective footprints, while preserving fiber quality at the same time. A single 170-Saw Imperial III gin stand can cruise at fifteen (15) bales per hour, and there are many that process up to eighteen (18) bales per hour under ideal conditions. Thus, a 4/170 gin plant can produce in excess of sixty (60) bales per hour, and there are numerous facilities around the world that demonstrate this type of performance on a regular basis.
For ELS cotton, Lummus’ Rota-Matic™ Roller Gin and Feeder are furnished in lieu of saw-type gin stands. The Rota-Matic has an effective width of 40” and a rated capacity of from 1.5 to 2 bales per hour per stand. Hence, a roller ginning plant will typically feature from as few as six (6) roller gins and feeders to as many as thirty (30), arranged in two lines of fifteen stands per line.

Lint Cleaning Systems

Now that the lint has been separated from the seed, it goes through some level of lint cleaning. Once again, depending upon whether the gin plant is processing Upland or ELS cotton, the lint cleaning specifications for the facility will be different. For saw-type gin plants, the first lint cleaner is typically a Lummus Super-Jet® Lint Cleaner, installed directly behind the saw-type gin stand. The Super-Jet®, which was pioneered by Lummus, uses centrifugal force to remove contamination from the lint. It is the only type of lint cleaner that does no fiber damage, since it has no moving parts.
From the Super-Jet®, the lint will be sent to either single (1) or tandem (2) saw-type lint cleaners, depending upon the amount of contamination in the lint. The saw-type lint cleaner combs the fibers while whipping them across grid bars that force the trash out into an air stream that pull them away from the saw. Lummus saw-type lint cleaners are available in two widths: 86” (for installation in 116-Saw ginning lines) and 108” (for 170-Saw ginning lines). There are also two types of Lummus saw-type lint cleaners. The most typical is the conventional controlled-batt-type (Model 86 and Model 108 Lint Cleaners), in which the lint cotton is condensed into a batt of fiber on a slow-moving, screen drum condenser. This batt is then fed through a feed works system onto the high-speed saw, which aggressively combs and aligns the fibers. In contrast to the controlled-batt-type, Lummus also offers its exclusive Sentinel™ Lint Cleaner (in both 86” and 108” widths), which does not condense the lint into a batt, but rather, feeds the individual tufts of lint onto the saw cylinder, reducing the aggressive action of the saw, and resulting in improved fiber properties within the sample (less short fiber content, less neps, better uniformity).

For ELS cotton, lint cleaning will consist of either a series of cylinder-type inclined cleaners feeding a Super-Jet® Lint Cleaner or Lummus’ exclusive Guardian™ Lint Cleaner. The Guardian™ features a lint condenser that feeds the lint batt onto a textile-type beater cylinder, which, in turn, feeds an integral Super-Jet® Lint Cleaner. In order to maintain their desired fiber properties, no saw-type lint cleaning is ever used on ELS cottons.

Condensing and Moisture Restoration System

The cleaned lint now travels via the Lint Flue to the battery condenser, which forms it into a blanket-like layer or batt. Lummus currently offers two styles of battery condensers, each in 60” and 80” diameters. The conventional Standard Battery Condenser features a revolving perforated drum that is doffed by a simple, three-roller doffing assembly. In most medium to high-capacity gin plants, the Moisture Conditioning (MC) Battery Condenser is furnished to allow for moisture restoration to the lint within the condenser itself, and its doffing assembly then serves to compress the moistened batt, thoroughly infusing the moisture throughout the fibers. If moisture is to be added to the lint batt from a Standard Battery Condenser, it is usually accomplished either through a array of spay nozzles mounted on the lint slide, or by the use of moist air induction through a set of louvers mounted in the bottom of the lint slide. Moisture restoration within the lint greatly enhances its compressibility with the baling press, reducing the forces required to compress the bale, and, thus, lowering energy costs.

Pressing and Bale Handling System

The final system within the gin plant consists of the press and bale handling system. Depending upon the region of the world, bales sizes are typically either 20” x 54” x 28” at 28 lbs/ft3 density (universal density or U.D.) or 20” x 41” x 28” at 32 lbs/ft3 density (high density or Hi-D). Lummus offers both U.D. and Hi-D presses in both the down-packing Lift-Box Dor-Les® (single-story) and up-packing Premier/Hi-D Dor-Les®) (two-story) versions. Depending upon the model and configuration of the press system, throughput capacity can range from twenty (20) bales per hour to in excess of sixty (60) bales per hour.

A variety of Bale Handling System components (dollies, chain conveyors, baggers, scales, accumulators, etc.) provides for any configuration required to move the finished bales for warehousing and/or shipment.