US3363286A

US3363286A - Method and apparatus for controlling the moisture content of natural fibers for cleaning and ginning

Info

Publication number: US3363286A
Application number: US443392A
Authority: US
Inventors: Howard A Scott; Bergman Ernest
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-03-29
Filing date: 1965-03-29
Publication date: 1968-01-16
Anticipated expiration: 1985-01-16

Description

363,286 LLING THE MOISTURE CONTENT ERS FOR CLEANING AND GINNING H. A. SCOTT ETAL Jan.16,1968

METHOD AND APPARATUS FOR CONTRO OF NATURAL FIB Filed March 29, v 1965 2 Sheets-Sheet 1' HOWARD A. $C077' Ex Rick UQK ma mm a) m g 4% Om, xi NE 5 3% U ofiw y 05 ERNEST BERGMAN INVENTORS M79151 ATTORNEYS Jan. 16, 1968 sco ET AL METHOD AND APPARATUS FOR CONTROLLING THE MOISTURE CONTENT OF NATURAL FIBERS FOR CLEANING AND GINNING Filed March 29, 1965 2 Sheets-Sheet 2 n N s m w M S 6 N R .m w m A B m y m m w. Mr M :M. Q 03 3 3 w m m ox QR t vm m6 5 ::Q: P g Q g h w A ll o 8 A 3 3 3 3 3 3 3 3 3 3\ 3 3 3 3 3 3 3 Q3 Q3 3% 3 3 3% g 3 0% mQ $3 B mm mm an a 3 3 3 3 3 3 .WQGkO Q w W; vx kuG IZQ QM vfil Wm; #3 95k Y .SQOQ Qhk MI United States Patent ABSTRACT 8F 1 H12 DESCLGSURE A method and apparatus for controlling the moisture content of natural fibers to facilitate their cleaning and ginning involving conveying the fibers in a continuous stream having a predetermined path, successively cleaning and subsequently ginning the fibers in the path, monitoring the moisture content of the fibers upstream from the cleaning operation, drying the fibers upstream from the cleaning operation in response to the monitoring of the fibers, monitoring the moisture content of the fibers upstream from the ginning operation and downstream from the cleaning operation, and moistening the fibers upstream from the ginning operation and downstream from the cleaning operation in response to the monitoring of the moisture of the fibers downstream from the cleaning operation.

The present invention relates to a method and apparatus for controlling the moisture content of natural fibers for cleaning and ginning purposes and more particularly to such a method and apparatus which provide for monitoring the moisture content of the fibers at selected preconditioning stages and adding moisture to the fibers or reducing moisture in the fibers to maintain a predetermined moisture content for eiiective cleaning and ginning with minimum damage to the fibers.

Although the present invention is adapted for use in the processing of many types of fibrous material, such as cotton, hemp, flax and the like, for convenience of description the invention is described in association with the ginning of cotton.

It is conventional in the ginning of cotton to draw the raw cotton from a transport vehicle into a duct for conveyance in a heated air stream through a series of dryers and cleaners to the gins for seed removal. Cotton drawn from the vehicle in an excessively dry state adheres to the duct walls and causes Waste and blockage. Cotton which is excessively moist is diificult to handle and almost impossible to clean and gin. Further, cotton must be treated carefully during the ginning process in order to preserve its quality, which is customarily graded on the length and tensile strength of its fibers. In a conventional ginning system, the cotton is dried in a heated air stream to facilitate the cleaning and removal of leaves, twigs, trash, and the like. The drying and heating is usually accomplished in several stages so as to avoid damaging the cotton fibers through extreme and abrupt changes in temperature and humidity. Notwithstanding such precautionary measures, cotton dried for cleaning often becomes brittle from lack of moisture and, in a conventional system, the fibers frequently suffer unnecessary damage from the gin saws when introduced into the gins.

Therefore, it is an object of the present invention to provide a method and apparatus for controlling the moisture content of natural fibers, such as cotton, for preconditioning, cleaning and ginning.

Another object is to provide such a method and apparatus which prevent the over-drying of the fibers.

Another object is to provide such a method and appa- Patented Jan. 16, 1%68 ratus which minimize damage of the fibers during the preconditioning, cleaning and drying as well as on the gin saws.

Another object is to provide such a method and apparatus which control the moisture content of the fibers prior to and during cleaning and drying.

Another object is to provide such a method and apparatus which control the moisture content of the fibers prior to ginning.

Another object is to provide such a method and apparatus which control the temperature of the fibers during cleaning and drying.

Another object is to provide such a method and apparatus which avoid sudden, excessive drying and moistenmg.

Another object is to provide such a method and apparatus which preserve the quality and tensile strength of the individual fibers during cleaning, drying and ginning.

Another object is to provide such a method and apparatus which are simple and economical to utilize.

These, together wtih other objects, will become more fully apparent upon reference to the following description and accompanying drawings.

In the drawings:

FIG. 1 is a schematic diagram of the process apparatus of the present invention.

FIG. 2 is a schematic circuit diagram of the power supply for the present invention.

Referring more particularly to the drawings:

A preferred apparatus for preconditioning cotton for ginning is shown schematically in FIG. 1. The apparatus includes an unloading duct it? for drawing raw cotton 13 from a wheeled transport vehicle 12 and introducing the cotton into an initial dryirn stage. The drying stage includes a conventional air separator 13A in which the seed cotton is dispersed to allow separation and removal of trash and other extraneous matter, not shown. A moist-air outlet duct 16A extends from the air separator for removal of moisture and trash. A suitable electric fan-type blower 15A is mounted in the outlet duct to provide an air stream for drawing the seed cotton through the unloading duct into the air separator. The separator separates the seed cotton from this initial air stream and allows the air stream to exhaust through the duct 16A.

A conventional hot-air blower unit is shown at 17A and consists preferably of an electric fantype blower 18A and a gas-operated heater 19A. Fuel, such as butane, is supplied to the heater through a gas line 21 leading from a supply source 22. The heater is activated by means of a suitable on-off gas-supply valve, such as a solenoid valve 23A operable in response to an electrical signal. It is regulated by a suitable motor-driven gas modulating valve 24A, which is also operable in response to an electrical signal. The blower and heater are connected in series through a hot-air duct 25A to the air separator 13A. The blower is of a size and capacity to provide a sufiicient air stream through the air separator to convey the separated cotton ll from the separator into a process duct 23A.

The process duct 28A connects the air separator 13A to a drying unit, preferably a conventional tower dryer 29A. The tower dryer is adapted to accommodate the full capacity of cotton fiow in air-ventilated gravitational dispersion effectively to allow drying of the cotton fibers a predetermined amount for subsequent cleaning.

A process duct 30 connects the dryer 29A to a conventional cleaning unit or cleaner 31A which utilizes rotating drums, brushes or the like, not shown, to clean trash and roughage from the seed cotton.

A second drying stage substantially similar to that described above is counected thereto by means of a process duct 32. In FIG. 1, elements of the second stage are num- 3 bered identically with those of the initial drying stage and are distinguished therefrom by the sufiix B. The second stage includes a blower unit 1713 with blower 18B and heater 19B, a hot-air duct 2513, an air separator 133, a moist-air outlet duct 163 with blower 158, a discharge duct 28B, and a tower dryer 293.

A process duct 33 leads from the tower dryer 298 to a third air separator 13C having a moist-air outlet duct 16C and blower C. The air separator 13C is connected to a third hot-air blower unit 17 C including elements similar to those described above and having identical numerical designations except for their sufiix C.

A process duct 36 leads from the third air separator 13C through two air cleaners 31B and C to a third tower dryer 290. A process duct 37 leads from the third tower dryer to a conventional inclined-type air cleaner 38 which discharges onto a feeder extractor or conventional elongated conveying belt 39. A moist-air outlet duct it) having a blower 41 is connected to the inclined air cleaner in a manner similar to'the moist air ducts 16A, B and C, described above.

A series of cotton gins .2 are positioned along the belt 39 and adapted in a conventional manner to receive cotton conveyed by the belt. The cotton gins are of conventional design and include rotating gin saws therein, not shown, for separating the cotton seeds from the fiber.

A suitable steam generating boiler 43 is connected through a steam conduit 44 to an injection nozzle 45 in the unloading duct 10. An automatically controlled steammodulating valve 46 of any suitable type, preferably electrically activatable, is provided in the steam conduit for control of the quantity of steam injected. A second steam line 47 connects the boiler to an injection nozzle 48 in the process duct 35 immediately upstream of the third tower dryer 29C. An automatically controlled steam-modulating control valve 49 is provided in the steam line for control of the injected steam, as required.

A suitable temperature sensing and control element, such as a thermostat St is provided at each of the tower dryers 29 for measurement of the drying temperature of the cotton therein. Each thermostat is connected through a control element 51 to the on-ofi gas-supply valve 23 for the corresponding upstream heater 19. The thermostats are set for a maximum drying temperature, which may be from 150 F. to 250 F. depending upon the type of cotton and particular apparatus utilized. Higher drying temperatures result in an excessive rate of drying with consequent damage to the cotton fibers.

A humidity sensing element, preferably an electric hygrometer 52, is mounted in each of the air-separator moistair outlet ducts 16. These hygrometers serve the purpose of measuring the moisture content of exhaust air and indicating the extent of heating by the hot-air blower units 17. Higher values of moisture content in the exhausting air indicate that more extensive heating has taken place with resultant higher temperatures of the cotton. Each of the hygrometers 52 is connected through any suitable control elements 53 to the gas-modulating valve 24 for the corresponding upstream heater 19, so that the valves 24 are operated in controlled response to signals from the respective hygrometers 52. Such circuitry is well-known in the art.

An electric hygrometer 54 is mounted in the unloading duct 10. It is connected through suitable control elements 57 to the steam supply valve 46. The steam valve is adapted to open in controlled response to the hygrometer signal to inject steam into the unloading duct and to bring the moisture content of the raw cotton 11 to a desired minimum value before entering the air separator 13A.

A humidity sensing element, also preferably an electric hygrometer 58, is mounted at the moist-air outlet duct 4% leading from the inclined cleaner 38. This hygrometer measures the moisture content of the cotton immediately steam control valve 49. The control valve 49 is operable to inject steam into the process duct 36 to increase the moisture content of the preconditioned cotton to a desired level in response to the signal received from the hygrometer 5S.

An electrical circuit for supplying power from a central source of alternating current 61 to the blowers 18 and the various sensing and control elements is shown schematically in FIG. 2. A double-pole single-throw switch s2 is provided for selectively opening and closing the circuit. Conductive elements 63 lead from a hot line 64 to the

respective sensing elements

59, 52, 54 and 58. Conductive elements 65 connect the valves 23, 24-, 46 and 49 to a common or neutral line 68. Similarly, leads as and 7% connect the blowers l5, l8 and 41, respectively, to the hot and common lines. A suitable ground, not shown, is also provided.

OPERATION The operation of the present invention is believed to be readily apparent and is briefly summarized at this point. A load of raw cotton 11 is stationed at the unloading duct 10. The first blower unit 15A causes a stream of air to blow through the unloading duct into the separator 13A, from which it discharges through the moist air outlet 16A. This stream of air sucks the raw cotton through the unloading duct into the air separator where the cotton is separated and the air is allowed to exhaust through the 7 outlet 16A. Loose trash, not shown, is carried out the moist air outlet. The separated cotton is carried into'process duct 28A by a heated air stream generated by the hotair blower unit 17 The hygrometerfid measures the moisture content of the raw cotton 11 as it enters the process. it has been found that a moisture content of at least 5% is desirable at entry. For values below thisamount the enteringv cotton fibers tend to adhere to the walls and roofs of the process apparatus due to the force of static electricity. At the point of entry, the hygrometer control signal actuates the steam control valve 46 to inject steam and to bring the cotton to the desired minimum humidity level.

The hy-grometer 5"2 senses whether the exhausting moist air has an excessive moisture content. Excessive moisture at this point indicates that too much moisture is being released by the heat. It has been found that for cleaning purposes a moisture content of about 4% is most efiective'. When the hygrometer senses that the discharging moisture is excessive, the gas modulating valve 24A is actuated to decrease the amount of heat and thus to maintain the cotton at the desired 4% humidity level for subsequent cleaning.

From the separator 13A the cotton is conveyed through duct 28A into the tower dryer 29A, from which it is drawn into the cleaner 31A and up into the separator 13B by means of the blower 15B of the next stage, which causes suction in the process lines 30 and 32. In a manner similar to that described above, the cotton is then conveyed successively into the second tower dryer 29B and up into the third separator 13C.

In order to maintain the cotton at optimum dryness for cleaning in each of the successive drying and cleaning stages, the hygrometers 52, the gas-modulating valves 24, and related control elements may be coordinatively utilized in any suitable manner following conventional control techniques and, therefore, are not set forth here in detail. In general, this phase of the process is accomplished by continuously regulating the amount of heat added by eachof the hot-air blower units 17 so as to control the amount of moisture removed.

If the cotton reaches the maximum drying temperature in any of the tower dryers 29, a control signal from the corresponding thermostat 5t) closes the on-off gas-supply valve 23 to (lo-activate the corresponding upstream heater 1?. The circuitry involved is shown schematically in FIG. 2 and is well-known for such purposes.

From the air separator 13C the cotton is conveyed through the cleaners 31B and 31C into the tower dryer 29C. The cotton is then conveyed to the final cleaning element 38 and discharged onto the conveyor belt 39 for delivery to the respective cotton gins 42.

The hygrometer 58 on the final moist-air outlet duct detects the moisture content of the preconditioned cotton immediately preceding ginning and transmits an electrical control signal to the steam control valve 4-9. It has been found that in cotton ginning a moisture content of about 7% to 8% allows the most efifective ginning with a minimum of damage to the cotton fiber. The steam control valve is regulated in controlled response to the hygrometer signal to inject the amount of steam necessary to bring the moisture content of the pro-conditioned cotton to the desired level.

At each of the cotton gins 42 a separate hygrometer is provided for indicating the moisture content of the cotton inside the individual gins. If desired, these may also be connected through suitable automatic control circuits, not shown, to the steam valve 49 to allow maintenance of an average over-all moisture content within the preferred limiting values.

For the purpose of the present invention, the steam may be introduced in any suitable manner at any process station, provided the steam is allowed fully to mix with the cotton mass. For this purpose, in the present embodiment the steam is injected at only two stations, namely, before the final tower dryer so as to give the steam adequate opportunity to mix with the cotton during its passage through the tower, and before entry into the first air separator 13A.

From the foregoing it is readily apparent that a method and apparatus has been provided for controlling the moisture content of a fiber, such as cotton, during its preconditioning for ginning. The invention allows effective control of the temperature and humidity in a stream of cotton during the entire dryin and cleaning process and allows pre-conditioning of the cotton fiber for ginning without damage thereto. The apparatus is structurally simple and economically operable.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent methods, devices and apparatus.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. The method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising the steps of conveying the fibers in an air stream confined in a pneumatic conduit; passing the fiber in said conduit through a heating chamber to release moisture from the fiber and to decrease the moisture content thereof to a determined residual value; monitoring the air flowing through said heating chamber to determine the moisture released from the fiber, the decrease in moisture content of said fiber being controlled by said air monitoring step; conveying the fiber in an air stream through a cleaning station and toward a ginning station; adding moisture to the fiber in said air stream prior to delivery to said ginning station; and monitoring the moisture content of the fiber following addition of said moisture, the addition of the moisture being controlled by the moisture content monitoring step to maintain a substantially predetermined level of moisture in the fiber.

2. The method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising the steps of conveying the fibers in an air stream confined in a pneumatic conduit; passing the fiber in said conduit through a heating chamber to release moisture from the fiber and decrease the moisture content to a determined residual value; monitoring the air flowing through said heating chamber to determine the moisture released from the fiber, the decrease in moisture content of said fiber being controlled by said air monitoring step; conveying the fiber in the air stream through a cleaning station and toward a ginning station; adding moisture in the form of steam to the air stream and the fiber prior to delivery to said ginning station; and monitoring the moisture content of the fiber following addition of said moisture, the addition of moisture being controlled by the moisture content monitoring step to maintain a substantially predetermined level of moisture in the fiber.

3. The method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising the steps of conveying the fibers in an air stream confined in a pneumatic conduit; passing the fiber in said conduit through a heating chamber to release moisture from the fiber; monitoring the air flowing through said heating chamber to determine the temperature of the air and the moisture released from the fiber; controlling the temperature of the air to decrease the moisture in the fiber to a determined residual value in controlled response to said air monitoring step; conveyin the fiber in the air stream through a cleaning station and toward a ginning station; adding moisture in the form of steam to the air stream and prior to delivery to said ginning station; monitoring the moisture content of the fiber following addition of said moisture; and regulating the rate and quantity of moisture added to maintain a determined value in the fiber prior to ginning and in controlled response to said moisture content monitoring step.

4. The method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising the steps of conveying the fibers in an air stream confined in a pneumatic conduit; monitoring the moisture content of the fiber upon entry into the air stream to ascertain whether a predetermined amount of moisture is present; adding moisture in the form of steam to the fiber upon entry thereof into the air stream to maintain the moisture content thereof at said predetermined amount; passing the fiber in said conduit through a heating chamber to release moisture from the fiber; monitoring the air flowing through said heating chamber to determine the temperature of the air and the moisture released from the fiber; controlling the temperature of the air to decrease the moisture in the fiber to a determined residual value; conveying the fiber in the air stream through a cleaning station and toward a ginning station; adding moisture in the form of steam to the air stream and prior to delivery to said ginning station; monitoring the moisture content of the fiber following injection of said moisture; and regulating the rate and quantity of moisture added to maintain a determined value in the fiber prior to ginning and in response to said moisture content monitoring step.

5. Apparatus for controlling the moisture content of fibers intended for subsequent processing comprising pneumatic conveying means confining a stream of air moving at a speed in relation to the mass and displacement of the fiber to support the same; heating means to elevate the temperature of the air and the fiber to a level sufiicient to release moisture from the fiber; exhaust means in communication with the conveying means downstream from the heating means and adapted to withdraw air containing moisture released from the fiber; humidity sensing means disposed in the conveying air stream downstream from the exhaust means to monitor the moisture content of the fiber; means to add steam to the air stream downstream from the exhaust means and to increase the moisture content of the fiber; control means for said steam addition means to maintain the moisture content of the air stream at a determined level downstream from said steam addition means; and fiber processing means disposed downstream from said steam addition means.

6. A method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising conveying the fibers in' a continuous stream having a predetermined path, successively cleaning and subsequently ginning the fibers in the path, monitoring the moisture content of the fiber upstream from the cleaning operation, drying the fiber upstream from the cleaning operation automatically in response to the monitor- 'ing of the moisture of the fiber by conveying a heated air stream through the fiber substantially to maintain a predetermined reduced level of moisture in the fiber for cleaning, the monitoring of the moisture content which controls the drying being performed by measuring the moisture content of the air stream after passage through the fiber, monitoring the moisture content of the fiber upstream from the ginning operation and downstream from the cleaning operation, and moistening the fiber upstream from the ginning operation and downstream from the cleaning operation automatically in response to the monitoring of the moisture downstream from the cleaning operation substantially to maintain a predetermined increased level of moisture in the fiber for ginning.

7. A method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising conveying the fibers in a continuous stream having a predetermined path, successively cleaning and subsequently ginning the fibers in the path, monitoring the moisture content of the fiber upstream from the cleaning operation, drying the fiber upstream from the cleaning operation automatically in response to the monitoring of the moisture of the fiber substantially to maintain a predetermined reduced level of moisture in the fiber for cleaning, monitoring the moisture content of the fiber upstream from the ginning operation and downstream from the cleaning operation, and moistening the fiber upstream from the ginning operation and from the monitoring which controls the moistening and downstream from the cleaning operation automatically in response to the monitoring of the moisture downstream from the cleaning operation substantially to maintain a predetermined increased level of moisture in the fiber for ginning.

8. A method of cleaning and ginning natural fibers and concurrently controlling the moisture content thereof comprising monitoring the moisture of the fiber, adding moisture to the fiber automatically in response to such monitoring substantially to attain a predetermined increased moisture level to minimize the generation of static electricity, conveying the fibers in a continuous stream having a predetermined path, successively cleaning and subsequently ginning the fibers in the path, monitoring the moisture content of the fiber upstream from the cleaning operation, drying the fiber upstream from the cleaning operation automatically in response to the monitoring of the moisture of the fiber substantially to maintain a predetermined reduced level of moisture in the fiber for cleaning, monitoring the moisture content of the fiber upstream from the ginning operation and downstream from the cleaning operation, and moistening the fiber upstream from the ginning operation and downstream from the cleaning operation automatically in response to the monitoring of the moisture downstream from the cleaning operation substantially to maintain a predetermined increased level of moisture in the fiber for ginning.

9. in a method for treating natural fibers including cleaning, ginning, or the like; a method for pro-treating fibers prior thereto to minimize the generation of static electricity and to precondition the fibers for subsequent treatment comprising monitoring the moisture content of the fiber, adding moisture to the fiber automatically in response to the monitoring of the moisture substantially .to attain a predetermined increased level of moisture in the fiber, subsequently again monitoring the moisture content of the fiber, and heating and ventilating the fiber to reduce the moisture content thereof automatically'in response to the second monitoring of the moisture to attain a predetermined decreased level of moisture in the fiber, the successive increasing and subsequent decreasing of the moisture in the fiber preconditioning the fiber for subsequent treatment.

References Cited MERVIN STEIN, Primary Examiner.

I. C. WADDEY, Assistant Examiner.