Textiles: fluid treating apparatus – Machines – Combined
Reexamination Certificate
2001-10-12
2003-09-16
Stinson, Frankie L. (Department: 1746)
Textiles: fluid treating apparatus
Machines
Combined
C068S207000, C127S028000
Reexamination Certificate
active
06619076
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved method and apparatus for cooking starch that is to be used in a commercial laundry application. Even more particularly, the present invention relates to an improved commercial starch cooking method and apparatus wherein a recirculating flow line reticulates the cooking starch solution through a recirculating pump at velocities of flow not previously achieved in starch cooking apparatus which promotes a more uniform heating of the starch batch and breaks up lumps in the starch. In the preferred embodiment of the invention, the starch is caused to exit the cooker at high velocity through a strainer in the form of a standpipe in the bottom center of the cooker vessel by a high velocity centrifugal circulating pump which discharges back into the vessel through a spray nozzle adjacent the periphery of the vessel thereby establishing a high velocity circulation of fluid in the vessel causing a vortex to be exhibited around the discharge standpipe to continually mix and homogenize the starch, and clean the vessel wall.
2. General Background of the Invention
During the cooking of starch two phenomena take place. Naturally occurring starch granules undergo considerable physical change, usually “swelling,” until they are complete disintegrated, and the starch molecules are hydrolyzed into smaller particles. The resulting modified starch material depends upon processing conditions that are very important in determining the physical characteristics of the final starch solution. The swelling or hydrolyzed modification of starch, if precisely controlled, allows starch to be useful as a size or adhesive.
A compact cooker, reliably and consistently operable by a relatively unsophisticated individual, would be desirable. At a minimum, the cooker should bring the water and starch charge to a workable temperature and maintain the mix in a status for dispensing into the laundry apparatus. For effective starching of clothing, it is essential that the starch be a homogenous mix of water and starch, that is, without lumps or other concentrations of starch which present an uneven texture or appearance to the fabric of the washed and starched garment. It is customary in “cooking starch” for laundry purposes to utilize temperatures in the 165° Fahrenheit thru 190° Fahrenheit range (preferably between 180° F. to 190° F.). At higher temperatures, i.e., above 212° F., the chemical and physical make up of the starch continues to change in such that the starch molecules begin to swell causing the volume of slurry to increase. As temperatures continue to rise, the starch molecules “burst” and the starch slurry no longer has the desirable properties as a sizing or adhesive.
The cooker must repeatedly perform the fill, cook and empty tasks with precision and regularity inherent in the design and operation of the machine and thus, without say sort of individual monitoring of the progress of the cooking procedure.
Several patents have issued for starch cooking devices. Some of the suggested patented systems require the use of a tank float device (e.g., U.S. Pat. No. 5,437,169 to Mitchell) to open and close the water supply valve via a solenoid. The float is immersed or partially immersed in the aqueous slurry of starch. Immersed operating components in starch solutions are a source of operating trouble. If the float becomes coated with starch, it fails to function, and presents overflow risks.
Some existing starch cookers (e.g., U.S. Pat. No. 5,437,169 to Mitchell; U.S. Pat. No. 2,730,468 to F. H. Martin; and U.S. Pat. No. 1,418,320 to E. W. Miller) use direct steam injection both to cook the starch and to agitate the starch solution. Existing cookers that use steam both to agitate and to cook often create starch solutions having lumps. It is believed that the concentrated heat of the steam directly on the starch solution causes localized heating and a temperature above that which the starch will remain stable as described above. These starch lumps cause uneven starching of the garments and a build up of starch on the press covers when the garments are pressed. Furthermore, direct steam induction results in sediment from within the boiler and or steam line to be mixed with the starch solution resulting in contamination (granular inclusions) and discoloration of the garments.
Other existing starch cookers (e.g., U.S. Pat. No. 5,437,169 to Mitchell, U.S. Pat. No. 2,940,876 to N. E. Elsas; and U.S. Pat. No. 2,516,884 to G. J. Kyame) use a plurality of valves to direct the contents of the containment tank either to the output conduit or the tank circulation. Problems have resulted from starch building up on such valves, including a failure of the valve to function.
Further problems with existing starch cookers involve the use of microprocessors to control a plurality of relays and process signals from various controlled communications. Microprocessors are particularly susceptible to heat and moisture, both of which are abundantly present in commercial laundries. When microprocessors are exposed to only minute amounts of moisture and/or heat they often cease to function. Thus, it would is desirable to provide a starch cooker which does not have the aforesaid susceptibility to heat and moisture.
Some large laundries use large vats of hot starch solutions and manually transfer hot starch from the vat to the washer. The manual transfer presents a danger of spillage and burning the operator. Another problem with this method is the large size of the vats and the consequently large quantities of starch. If the entire amount of starch is not used the same day it is prepared, the residual will frequently spoil and impart an unpleasant odor to the garments.
Other unsuccessful approaches at effective starch cookers are illustrated in U.S. Pat. No. 5,964,950 to Boling, the present inventor, wherein an external stand pipe is utilized to determine the fluid level within the vessel which, once the batch of starch is cooked and the slurry removed from the tank, residue of the slurry remains within the standpipe and creates an additional impediment to refill water rise in the pipe and erroneous readings occur. The patent also recites the inclusion of a gear pump for recirculating the slurry theorized to materially contribute to the break up of lumps. In operation, it has been found that the gear pump was only marginally effective in the breaking up of starch lumps and also exhibited a tendency to clog. In this previous cooker, it was theorized the use of a gear pump would blend the starch using the gears of the pump as a grinder. Through further operation, it has been found that with the use of gears, the starch revolved around the gears using the gears like paddles around the interior of the body when it was anticipated that the starch would be drawn through the center of the gears and therefore the meshing gear teeth would break up any lumps that had formed in the starch.
Through further evaluation it has been determined that the circulation of the starch with this particular prior art pump was approximately 3 gal per minute. When using straight water in the cook tank, prior to the adding starch, one would observe significant movement of the water in the tank. Once starch was added to this water, the movement due to the viscosity of the liquid slowed down considerably, more so than expected. The gear pump demonstrated the ability to pump on a free flow a maximum rate of 4 gal per minute with a liquid that was very thin such as water.
According to the present invention, the flow rate of the combined mix of starch and water, by using a centrifugal pump of about a ⅓ HP rating, with an inlet size of 1″ and an outlet size of ¾″, which will pump on free flow about forty gallons per minute using a liquid such as water can provide
Stinson Frankie L.
Wyatt Tarrant & Combs, L.L.P.
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