Abstract:
Methods and systems for treating cooling water of a retort are described. The methods and systems generate an aqueous ozone solution and combine the aqueous ozone solution with the cooling water. The methods and systems provide a safe, economical, easy to handle, and environmentally friendly solution for maintaining a retort cooling water system. The systems and methods herein remove contaminates from the cooling water, supply a continuous sanitizer created on-site, reduce the need for additional chemicals, and reduce the labor costs attributed to maintaining the retort cooling water system.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/788,097, filed Mar. 15, 2013, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF INVENTION 
     The present invention relates to methods and systems for controlling microorganisms and turbidity in retort cooling water using an aqueous ozone solution. 
     BACKGROUND 
     Retort canning operations are engineered in many fashions, including still, batch, continuous, vertical, and horizontal designs. The retort canning operations all perform the same function, namely to thermally cook a canned product to a temperature suitable for sterilization. 
     An important aspect of almost all retort canning operations is the use of a cooling stage or process that cools the water that has seen used in the retort to cool the cans. During the cooling, the water may become fouled from ruptured cans or spilled foods. During the cooling, the water is also heated by the cans. During the cooling process, the seams of the can are very fragile, and the cans must be handled very carefully. The water used during the cooling stage must have a sanitizer to disinfect it in case the water is sucked into the can during the cooling stage. As such, choosing the right product for sanitizing is an important decision. 
     Traditionally, chlorine is the sanitizing product of choice for use during the cooling stage. However, chlorine has many substantial drawbacks. The use of chloride does not eliminate the need to use and maintain supplies of degreasers, dispersants or flocculants, and rust inhibitors. This is a very complex matrix of chemicals to manage in a cooling system. These chemicals are also very expensive, unsafe to handle, and require proper management of buying, ordering, and storage. These chemicals also require constant monitoring by trained personnel. Due to employee turnover, training must be constantly implemented to train new employees. Further, meters and testing equipment must be recalibrated and maintained. The maintenance of a typical retort cooling water system may cost hundreds of thousands of dollars annually in chemicals and labor. 
     SUMMARY 
     Described herein are methods and systems for using an aqueous ozone solution in retort cooling water systems. The methods and systems generate an aqueous ozone solution and combine or mix the aqueous ozone solution with the cooling water. The methods and systems provide a safe, economical, easy to handle, and environmentally friendly solution for maintaining a retort cooling water system. The systems and methods herein remove contaminates from the cooling water, supply a continuous sanitizer created on-site, reduce the need for additional chemicals, and reduce the labor costs attributed to maintaining the retort cooling water system. 
     The use of the aqueous ozone solution in a retort operation serves many functions. The aqueous ozone solution keeps the water in excellent condition. The aqueous ozone solution flocculates solids for removal. The aqueous ozone solution provides for biological control of contaminates in the water. The aqueous ozone solution reduces spoilage of food products in the by providing the biological control of the contaminants in the water. 
     In one aspect, a method for maintaining retort cooling water is described. The method includes forming an aqueous ozone solution and directing the aqueous ozone solution to a cooling water holding tank. The cooling water holding tank contains an amount of cooling water. The method includes combining the aqueous ozone solution with the cooling water in the cooling water holding tank. 
     In another aspect, a method for maintaining retort cooling water is described. The method includes forming an aqueous ozone solution. The method further includes directing the aqueous ozone solution to a retort cooling water system containing cooling water. The method further includes combining the aqueous ozone solution into the cooling water. The method further includes circulating the cooling water through the retort cooling water system. The method further includes overflowing a holding tank of the retort cooling water system. The method further includes draining a portion of the cooling water from the holding tank to remove flocculates, contaminants, minerals, soaps, etc. 
     In another aspect, a method of maintaining a cooling a retort system is described. The method includes forming an aqueous ozone solution. The method further includes directing the aqueous ozone solution to a cold water holding tank, the cold water holding tank containing an amount of cold water. The method further includes mixing the cold water with the aqueous ozone solution to form ozonated cold water. The method further includes directing the ozonated cold water to a retort system. The method further includes cooling cans with the ozonated cold water in the retort system, whereby the ozonated cold water is heated. The method further includes directing the heated ozonated water to a hot water holding tank. The method further includes directing the heated ozonated water from the hot water holding tank to a cooling tower for cooling. The method further includes cooling the heated ozonated water. The method further includes directing the cooled ozonated water to the cold water holding tank. The method further includes draining a portion of the cooled ozonated water from the cold water holding tank. 
     In another aspect a retort cooling water system is described. The system includes a cold water holding tank. The cold water holding tank includes a weir fluidically engaged to a drain. A hot water holding tank is fluidically engaged to a retort. The system includes a cooling tower fluidically connected to the hot water holding tank via a cooling tower supply line. The system includes a cooling tower return line that fluidically connects the cooling tower to the cold water holding tank. An aqueous ozone solution generator supplies aqueous ozone solution to the cold water holding tank. 
     In another aspect a retort cooling water system is described. The system includes a cold water holding tank, which includes a weir fluidically connecting to a drain. A hot water holding tank fluidically connects to the cold water holding tank via a valve or opening between the cold water holding tank and the hot water holding tank. The system includes a retort. A retort supply line fluidically connects the retort and the cold water holding tank. A hot water tank return line fluidically connects the retort and the hot water holding tank. The system includes a cooling tower. A cooling tower supply line fluidically connects the hot water holding tank and the cooling tower. A cooling tower return line fludically connects the cooling tower and the cold water holding tank. An aqueous ozone solution generator is fluidically engaged to the system to provide the system with aqueous ozone solution. 
     In another aspect, a retort cooling water system is described. The system includes a cold water holding tank and a hot water holding tank. The system includes a cooling tower supply line fluidly connecting the hot water holding tank and the cooling tower. The system includes a cooling tower return line fluidly connecting the cold water holding tank and the cooling tower. The system includes an aqueous ozone solution generator, wherein the aqueous ozone solution generator supplies aqueous ozone solution to the cold water holding tank. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view of the retort water cooling system with the aqueous ozone solution generator supplying the cold water tank. 
         FIG. 2  is a plan view of the retort water cooling system with the aqueous ozone solution generator drawing water from the cold water tank to form the aqueous ozone solution. 
         FIG. 3  is a plan view of the retort water cooling system with the aqueous ozone solution generator supplying the retort. 
         FIG. 4  is a plan view of the retort water cooling system with the ozone generator  90  supplying the retort supply line with ozone gas. 
         FIG. 5  is a view of the weir. 
         FIG. 6  is a view of the weir with the paddle system. 
         FIG. 7  is a view of the weir with the blower system. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     Described herein are methods and systems for using ozone in retort cooling water system. The methods and systems generate an aqueous ozone solution and mix the aqueous ozone solution with the cooling water. 
     With reference to  FIG. 1 , a retort water cooling system  10  is shown. The retort cooling water system  10  includes a hot water holding tank  20  and a cold water holding tank  30 . Cold water from the cold water holding tank  30  is directed to a retort  40  via a retort supply line  45  in order to be sprayed on or circulated about cans or other vessels in the retort  40  that have been heated for sterilization. The cold water cools the heated cans or heated vessels in the retort  40 . During the cooling process, the cold water is heated to hot water from the transfer of heat from the retort  40 . The hot water is drawn from the retort  40  via a hot water tank return line  60  and directed to the hot water holding tank  20 . The hot water may be contaminated or fouled from ruptured cans or from other food products on the exterior of the cans. 
     The hot water holding tank  20  is in fluidic communication with one or more cooling towers  50  via a cooling tower supply line  70 . The hot water is directed to the cooling towers  50  via the cooling tower supply line  70 . At the cooling towers  50 , the hot water is cooled. The hot water may pick up contaminates or other particulate during the cooling process. The cooling towers  50  are in fluidic communication with the cold water holding tank  30  via a cooling tower return line  80 . The cooling tower return line  80  supplies the cold water holding tank  30  with the cooled water from the cooling tower  50 , which is again returned to the retort  40  as part of continuous cycle or process. 
     An ozone generator  90  supplies the cold water holding tank  30  with a supply of aqueous ozone solution. The aqueous ozone solution is mixed or combined with the cold water already present in the cold water holding tank  30 . In other aspects, the aqueous ozone solution is directed to other parts of the system  10 . 
     A municipal water supply is connected to the ozone generator  90  via a water supply line  100 . The ozone generator  90  forms ozone gas and injects the ozone gas into the water from the municipal water supply to form the aqueous ozone solution. The ozone generator  90  supplies the cold water holding tank  30  with the aqueous ozone solution via an aqueous ozone solution supply line  110 . 
     The ozone generator  90  may continually supply the retort cooling water system  10  with the aqueous ozone solution. A portion of the fluid from the retort cooling water system  10  is usually continually lost from steam emission, cooling processes, filtering, leaks, etc. The aqueous ozone solution may replace or be in addition to other make-up water or fluids that are supplied to the retort cooling water system  10 . 
     The hot water holding tank  20  and the cold water holding tank  30  may be fluidly connected to maintain proper water levels in the tanks  20  and  30 . The cold water holding tank  30  and the hot water holding tank  20  may be fluidly connected by a valve or other opening. For example, a gate valve  120  may provide the fluidic communication between the tanks  20  and  30 . The gate valve  120  provides for an equilibrium of water levels to be maintained between the cold water holding tank  30  and the hot water holding tank  20 . The fluids in the two tanks  20  and  30  may pass back and forth through the gate valve  120  to maintain an equal level between the hot water holding tank  20  and the cold water holding tank  30 . The cold water holding tank  30  may also be fluidly connected to the municipal water supply to provide make-up water to the cold water holding tank  30 . The municipal water supply may also be connected to other portions of the retort cooling water system  10  to provide make-up water for the system  10 . 
     With reference to  FIG. 5 , a weir  130  is positioned in the cold water holding tank  30  to remove floating particulate and/or a portion of the uppermost volume of water in the cold water holding tank  30 . The weir  130  may span an edge of the cold water holding tank  30 . Multiple weirs  130  may also be positioned in the cold water holding tank  30 . Other surface positioned drains may also be employed in the cold water holding tank  30 . The weir  130  may be positioned at a level approximately equal to the desired maximum level of water in the cold water holding tank  30 . The weir  130  includes an upper edge  135  proximate a surface level  35  of the water in the cold water holding tank  30 . The cooling tower return line  80  supplies the cold water holding tank  30  with cold water. As additional fluid is also added to the cold water holding tank  30 , the level of cold water in the cold water holding tank  30  may rise and the cold water will eventually overflow the weir  130  and drain from the cold water holding tank  30  via a drain  150 . In detail, the cold water overflows the upper edge  135  of the weir  130  and then proceeds to the drain  150 . The drain  150  may be in fluid communication with municipal waste water sewers. 
     The additional fluid to overflow the cold water holding tank  20  may be provided from the ozone generator  90 , which is adding the aqueous ozone solution to the cold water holding tank  30 . The additional fluid to overflow the weir  130  may also be provided from municipal make-up water added directly to the cold water holding tank  30 . The additional fluid may also be provided from other ozone generators  90 , which are adding the aqueous ozone solution to other portions of the system  10 . 
     The overflowing of the weir  130  provides significant benefits. For example, fats, grease, and oils leaked from the cans in the retort  40  are saponified into soaps by the oxidizing nature of the aqueous ozone solution. The soaps may rise in the water column of the cold water holding tank  30  to the surface  35  of the water in the cold water holding tank  30  where it may be removed by the weir  130 . Other particulate, contaminants, minerals, flocculate, etc. may also collect on or near the surface of the cold water in the cold water holding tank  30 . The soaps, particulate, contaminants, minerals, flocculate, etc. may all overflow the weir  130  and be removed from the retort cooling water system  10 . The weir  130  drains off the top volume from the cold water holding tank  30  to remove flocculates, contaminants, minerals, soaps, etc. that have floated to the top of the water level. The overflow into the weir  130  may be caused by the input of ozone solution and/or make-up water added to the system. In other aspects, the weir  130  or additional weirs  130  are integrated into the hot water holding tank  20  to remove contaminants, minerals, flocculate, etc. from the hot water holding tank  20 . The ozone generator  90  may also supply the hot water holding tank  20  with the aqueous ozone solution. 
     The methods herein include adding additional fluid to the retort cooling water system  10  such that water is constantly, near constantly, or routinely overflowing the weir  130 . In other methods, the weir  130  may also be intermittently overflowed. The overflowing of the weir  130  may also be timed with operation of the retort  40 . The overflowing of the weir  130  may be timed with a cleaning cycle for the retort cooling water system  10 . 
     With reference to  FIG. 6 , a paddle system  160  is engaged to the cold water holding tank  30 . The paddle system  160  urges the water and particulate matter to the weir  130  and to eventually overflow the weir  130 . Other types of mechanical skimmers may be used to urge particulate, soaps, minerals, flocculate, and other contaminants to the weir  130 . Agitators, hydraulic pumps, or other devices may be used to circulate the cold water or move the cold water towards to the weir  130 . 
     With reference to  FIG. 7 , a blower system  170  is engaged to the cold water holding tank  30 . A blower  175  may be positioned near a bottom of the cold water holding tank  30 . The blower  175  circulates the water in the cold water holding tank  30  to move the particulate, soaps, flocculate, and other contaminants towards the weir  130 . The blower  175  may include a diffuser  180  to assist in directing the water. The blower  175  may also be engaged to other nozzles, hoses, and other valves to emit air throughout the cold water holding tank  30 . Other types of bubblers may be used to circulate the cold water or move the water towards to the weir  130 . 
     As described above, the aqueous ozone solution may be generated and directed to the cold water holding tank  30  to cause the cold water to overflow the weir  130  on a near constant basis to provide continual flushing and cleaning of the retort cooling water system  10 . As described below, the aqueous ozone solution may also be generated and provided to the retort cooling water system  10  in several fashions. 
     With reference to  FIG. 2 , the ozone generator  90  draws water from the cold water holding tank  20  via a supply line  190 . In this aspect, the aqueous ozone solution is formed from the water from the cold water holding tank  30  and then returns the aqueous ozone solution to the cold water holding tank  30 . 
     With reference to  FIG. 3 , the ozone generator  90  supplies the aqueous ozone solution to the retort  40  via an aqueous ozone solution supply line  200 . In this aspect, the ozone generator  90  is directly supplying the retort supply line  45  with the aqueous ozone solution. 
     With reference to  FIG. 4 , an ozone generator  91  supplies ozone gas to an injector  210  positioned in the retort supply line  45 . A mixer  220  may also be positioned in the retort supply line  45  after the injector  210 . Thus, the injector  210  injects the ozone gas into fluid in the retort supply line  45 , and the mixer  220  further mixes the aqueous ozone solution. 
     The injector  210  injects the ozone gas into the fluid from the injector line  160 . The injector  210  may include a mazzei injector or other type of venturi to mix the ozone gas with the water. Any of a variety of injectors could be utilized. The injector  210  creates a vacuum to draw the ozone gas from the ozone generator  91  and then dissolves the ozone in the fluid from the retort supply line  45 . 
     The mixer  220  further processes the fluid to reduce the bubble size of the ozone gas in the fluid. The mixer  220  further reduces the number of ozone gas bubbles in the ozonated fluid to increase the concentration of ozone in the ozonated fluid. Breaking down the bubbles of ozone into smaller bubbles of ozone increases the oxidation reduction potential of the ozone in the fluid. 
     Although a single ozone generator  90  is shown in the FIGS., additional ozone generators  90  may be placed about or engaged to the retort cooling water system  10  to provide aqueous ozone solution to the cooling tower  50 , the retort  40 , the cold water holding tank  30 , and/or the hot water tank  20 . 
     A filtering system may also be employed with the retort cooling water system  10 . The filtering system may be in fluidic communication with the hot water holding tank  20 . The filtering system draws hot water from the hot water holding tank  20  and filters the hot water. The filtering system may remove particulate matter from the hot water in the hot water holding tank  20 . The filtering system removes the hot water from the hot water holding tank  20 , filters, the hot water, and returns the hot water to the hot water holding tank  20 . A similar filtering system may also be employed in the cold water holding tank  30 . 
     The methods and systems may use an aqueous ozone solution generators commercially available from Food Safety Technology, LLC of Omaha, Nebr. Such aqueous ozone solution generators are described in U.S. Patent Publications Nos. 2009/0120473, 2011/0030730, 2013/0142704, and 2013/0195725, which are hereby incorporated by reference in their entirety. Generally, such ozone generators produce ozone gas and then inject the ozone gas into water to form the aqueous ozone solution. 
     The ozone generator  90  generates a supply of the aqueous ozone solution. A municipal water supply may supply the ozone generator  90  with water to be ozonated. After formation, the aqueous ozone solution is directed to the cold water holding tank  30  via the aqueous ozone solution supply line  110  and mixed or combined with the cold water therein. The aqueous ozone solution is circulated throughout the retort cooling water system  10 . The aqueous ozone solution is circulated to the retort  40  and sprayed directly on the cans or circulated about the cans. In detail, the aqueous ozone solution is circulated through the cold water holding tank  20 , through the retort supply line  45 , through the retort  40 , through the hot water tank return line  60 , thorough the hot water holding tank  30 , through the cooling tower supply line  70 , through the cooling tower  50 , through the cooling tower return line  80 , and back to the cold water holding tank  20 . The aqueous ozone solution cleans and sanitizes of all of these components. Importantly, the cold water holding tank  20  is maintained by the aqueous ozone solution, and the particulate, soaps, flocculate, and other contaminants towards are removed from the system  10  by the weir  130  to substantially improve turbidity levels of the water. 
     ORP sensors and monitors may be integrated into the retort cooling water system  10  to monitor and measure ORP levels of the aqueous ozone solution. Depending on ORP readings, the ozone generator  90  may modulate the concentration or volume of the aqueous ozone solution provided to the cold water holding tank  30  or other part of the system  10 . The ozone generator  90  may regulate the ORP of the water in the system to maintain an ORP of approximately 250-450 millivolts. 
     The methods and system provide microbial control for the retort cooling water. The FDA mandates the microbial control of cooling water. The FDA mandates that cooling water shall be chlorinated or otherwise sanitized as necessary for cooling canals and for re-circulated water supplies, and that there shall be a measurable residual of the sanitizer employed at the water discharge point of the container cooler. The aqueous ozone solution formed from the ozone generator  90  satisfies these requirements. 
     The use of an aqueous ozone solution helps manage the sanitizer level of the cooling water. The aqueous ozone solution maintains constant levels of sanitizer in the solution even with blown, buckled, or dirty cans in the retort. The system  10  maintains a level of 100 CFU per ml or less for the cooling water. 
     The use of aqueous ozone solution also provides additional advantages by improving the appearance of the cans processed by the retort  40 . The aqueous ozone solution has the ability to oxidize iron and manganese very rapidly to form a black flocculate that settles out of the water. The black flocculate accumulates on the bottom of the tanks  20  or  30 . This helps reduce the water spots on cans. 
     The use of aqueous ozone solution provides additional advantages by saving money spent on chemicals. The use of the aqueous ozone solution may replace or reduce the use of biocides, rust inhibitors, and dispersants in the typical retort water cooling system. The maintenance of the typical retort cooling water system may cost hundreds of thousands of dollars annually in chemicals and labor. 
     Moreover, the use of conventional chemicals is often counter-productive. This dilemma is caused by the fact that the three chemicals (biocides, rust inhibitors, and dispersants) often work against each other and create additional problems. The biocide will cause rust, so corrosion inhibitors are added. The corrosion inhibitors conglomerate to particles in the water, so dispersants are added, and the matrix continues. The use of aqueous ozone solution prevents or reduces this cascade of chemical use. The use of the methods and systems using the aqueous ozone solution may provide a significant financial and labor savings. The use of the methods and systems using the aqueous ozone solution may replace or reduce the need for conventional chemicals and treatments typically used in cooling systems. 
     The use of ORP is proven as a measurement of the killing power of a sanitizer in water. ORP stands for oxidation reduction potential. The system  10  provides an aqueous ozone solution with an ORP of approximately 250-450 millivolts. Thus, the aqueous ozone solution is a suitable oxidizer. Further, the ORP level may be raised by increasing the flow and/or concentration of the aqueous ozone solution into the system  10 . 
     The use of aqueous ozone solution provides additional advantages by controlling rust on cans. During the seaming of the cans, the machinery will often scuff or scrape the can, which exposes the metal to water, which causes rust. The presence of rust on a can is undesirable to consumers, resulting in product rejection, and ultimately costs the company money and goodwill because of the rejected product. The science of using an aqueous ozone solution in the retort process changes the rust formulation of the metal from red (hematite) rust to black (magnetite) rust. Magnetite rust is generally acceptable to consumers and such cans will typically be purchased with minimal issues. 
     The formulas for typical iron oxides are described below: 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Formula 
                 Color 
                 Oxidation State 
                 MP 
                 Structure/comments 
               
               
                   
               
             
             
               
                 Fe 2 O 3   
                 red brown 
                 Fe 3+   
                 1560d 
                 α-form Hematite, β-form 
               
               
                   
                   
                   
                   
                 used in cassettes 
               
               
                 Fe 3 O 4   
                 black 
                 Fe 2+/3+   
                 1538d 
                 magnetite/lodestone 
               
               
                 FeO 
                 black 
                 Fe 2+   
                 1380 
                 pyrophoric 
               
               
                   
               
             
          
         
       
     
     The commonly referred to “rust” is the flaky red-brown solid, which is largely hydrated iron. The primary corrosion product of iron is Fe (OH)  2  (or more likely FeO.nH 2 O), but the action of oxygen and water can yield other products having different colors: 
     1. Fe 2 O 3 .H 2 O (hydrous ferrous oxide, sometimes written as Fe (OH) 3 ) is the principal component of red-brown rust. It can form a mineral called hematite. 
     2. Fe 3 O 4 .H 2 O (“hydrated magnetite” or ferrous ferrite, Fe 2 O 3 .FeO) is most often green but can be deep blue in the presence of organic compounds. 
     3. Fe 3 O 4  (“magnetite”) is black 
     The use of aqueous ozone solution in the retort eliminates or reduces the need for a plant to use a rust inhibitor in the retort water, which saves large amounts of money because of the above chemical processes. The aqueous ozone solution oxidizes to the “magnetite” level with iron, which is more acceptable then the red or “hematite” rust on cans. 
     The aqueous ozone solution also provides biological control of the retort cooling tower. This is important because the cooling tower is used to remove the heat from the water, which removes the heat from the cans. The use of the methods herein reduces the buildup of scale and/or organic films on the cooling tower. This results in cost savings for the company. 
     The aqueous ozone solution also provides a degreaser and organic remover. The aqueous ozone solutions have the ability to react with the grease and the fats in the hot water from the retort to form the soaps, which may be removed by the weir  130  to maintain water quality in the retort cooling water system  10 . The use of the method and systems herein reduce turbidity in the system  10 . The soaps, particulate, minerals, and other contaminants may pass over the weir  130  and be removed from the retort cooling water system  10 . The use of the weir  130  assists in removing the contaminated products and helps to keep the water clean and reduces turbidity. 
     The ozone generator  90  may provide an aqueous ozone solution to the system  10  at a flow rate of up to approximately 50 GPM with an ORP of up to 10 PPM. In certain applications, a flow rate of 16 GPM with an ORP of approximately 6-8 PPM provides satisfactory cleaning and microorganism control for the system  10 . This flow and concentration maintains a standard ORP level which gives low CFU counts in the water to help prevent spoilage of cans. The flow rates and ORP from the ozone generator  90  may be adjusted as needed. 
     The aqueous ozone solution also helps keep the filter system clean by floating the solids out of the water and away from the system and to the drain. The methods and systems reduce the frequency of the filter handling and tank cleaning labor. The safety factor of not having to get into the tanks to clean is a benefit to plant safety managers. The use of the methods and system herein drastically reduce plant down time caused by cleaning the cold and hot water holding tanks. Further, sewer lines connected to the system  10  require less cleaning.