Cleaning and liquid contact with solids – Processes – Combined
Reexamination Certificate
2002-12-18
2004-07-27
El-Arini, Zeinab (Department: 1746)
Cleaning and liquid contact with solids
Processes
Combined
C134S022100, C134S022110, C134S022120, C134S022180, C134S026000, C134S028000, C134S029000, C134S041000, C134S05600D, C134S113000
Reexamination Certificate
active
06767408
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device and methods for operating a clean-in-place system, and more particularly to a monitoring device and monitoring methods that optimize the control sequence of the inlet valves and the outlet valves of the fluid storage tanks and the waste disposal lines of a clean-in-place system.
2. Description of the Related Art
Food processing equipment, such as that found in dairies, breweries, and carbonated beverage plants, typically includes tanks, pumps, valves and fluid piping. This food processing equipment often needs to be cleaned between each lot of product processed through the equipment. However, the tanks, pumps, valves and piping can be difficult to clean because the various components may be difficult to access and disassemble for cleaning. Because of these cleaning difficulties, many food processing plants now use clean-in-place systems in which the tanks, pumps, valves and piping of the food processing equipment remain physically assembled, and various cleaning, disinfecting and rinsing solutions are circulated by the clean-in-place system through the food processing equipment to effect the cleaning process.
An example clean-in-place cleaning cycle normally begins with a pre-rinse cycle wherein water is pumped through the food processing equipment for the purpose of removing loose soil in the system. Typically, an alkaline wash would then be recirculated through the food processing equipment. This alkaline wash would chemically react with the soils of the food processing equipment to further remove soil. A third step would again rinse the food processing equipment with water, prior to a fourth step wherein an acid rinse would be circulated through the batch processing system. The acid rinse would neutralize and remove residual alkaline cleaner and remove any mineral deposits left by the water. Finally, a post-rinse cycle would be performed, typically using water and/or a sanitizing rinse. Such clean-in-place systems (and associated cleaning compositions) are known in the art, and examples can be found in U.S. Pat. Nos. 6,423,675, 6,391,122, 6,161,558, 6,136,362, 6,089,242, 6,071,356, 5,888,311, 5,533,552, 5,427,126, 5,405,452, 5,348,058, 5,282,889, 5,064,561, 5,047,164, 4,836,420, and 2,897,829, which are incorporated herein by reference.
While known clean-in-place systems have proven to be effective in cleaning the components of food processing equipment, they are not without drawbacks. Typically, fluid flow in a clean-in-place system is controlled by a programmable logic controller that controls activation of the clean-in-place system valves. Typically, the PLC programmer configures the software in the PLC to provide “open” and “close” signals to the valves to achieve a predetermined wash or rinse time. These wash or rinse times are typically based on estimated piping lengths in the apparatus being cleaned.
The use of estimated pipe lengths in the PLC programming can cause problems in operation of the clean-in-place system. For example, the rinse steps in the clean-in-place process may be of insufficient duration to clean solids from the apparatus being cleaned. Improper calculation of the duration of rinse times can lead to higher water or sewer charges, and may also lead to the introduction of rinse water to cleaning composition tanks thereby diluting the cleaning composition in the tanks. Improper calculation of the duration of the various steps in the clean-in-place process can also lead to introduction of caustic or acidic compositions to the clean-in-place system drain, which may be undesirable in view of environmental restrictions.
Thus, there is a need for a monitoring device and monitoring methods that optimize the control sequence of the inlet valves and the outlet valves of the fluid storage tanks and the waste disposal lines of a clean-in-place system. In particular, there is a need for a monitoring device and monitoring methods for a clean-in-place system wherein the device and methods improve the cleaning of solids from the apparatus being cleaned, minimize water or sewer charges, limit the introduction of caustic or acidic compositions to the clean-in-place system drain, and limit the introduction of rinse water to the clean-in-place system cleaning composition tanks.
SUMMARY OF THE INVENTION
The present invention satisfies the foregoing needs by providing a method for cleaning an apparatus using a clean-in-place system wherein the clean-in-place system is in fluid communication with an inlet of the apparatus and the clean-in-place system is in fluid communication with an outlet of the apparatus. In the method, a cleaning composition is supplied from a cleaner tank of the clean-in-place system into the inlet of the apparatus for a first period of time of a first cleaning cycle. The cleaning composition has a measurable physical property (e.g., flow rate, pH, conductivity, turbidity, suspended solids, concentration, density and temperature) at a first measured value. The cleaner tank has a cleaner supply valve and a cleaner return valve such that the cleaning composition may be recirculated through the cleaner tank and the apparatus.
A rinsing composition from a rinse tank of the clean-in-place system is supplied into the inlet of the apparatus for a second period of time of the first cleaning cycle. The rinsing composition has the measurable physical property at a second measured value different from the first measured value of the cleaning composition. The measurable physical property is sensed versus time for fluids exiting the outlet of the apparatus, and a circulation time of the cleaning composition from a predetermined time of the first period of time of the first cleaning cycle to an end time wherein the measurable physical property of the fluids has a third measured value different from the first measured value is determined. This provides for the location as a function to time of an interface between the cleaning composition and the rinsing composition. A cleaner return valve closing time for closing the cleaner return valve is then determined in dependence on the circulation time. The cleaner return valve closing time is then used after supplying the cleaning composition from the cleaner tank and thereafter supplying the rinsing composition from the rinse tank in a subsequent cleaning cycle. Preferably, the cleaner return valve closing time is selected such that no rinsing composition enters the cleaner tank during the subsequent cleaning cycle.
In another aspect of the present invention, the measurable physical property is sensed versus time for fluids exiting the outlet of the apparatus, and a circulation time of the cleaning composition from a predetermined time of the first period of time of the first cleaning cycle to an end time wherein the measurable physical property of the fluids has a third measured value different from the first measured value is determined. This provides for the location as a function to time of an interface between the cleaning composition and the rinsing composition. A drain valve closing time for closing a drain valve of the clean-in-place system is then determined in dependence on the circulation time. The drain valve closing time is then used after supplying the cleaning composition from the cleaner tank and thereafter supplying the rinsing composition from the rinse tank in a subsequent cleaning cycle. Preferably, the drain valve closing time is selected such that no cleaning composition enters the drain during the subsequent cleaning cycle.
In yet another aspect of the present invention, a rinsing composition is supplied from a rinse tank of the clean-in-place system into the inlet of the apparatus for a period of time. The rinsing composition has a measurable physical property at a first measured value. The rinse tank has a rinse supply valve and is in fluid communication with a drain or a solids r
Bohanon Leo F.
Kenowski Andy
El-Arini Zeinab
Hydrite Chemical Co.
Quarles & Brady LLP
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