Like many engineers, I have casually drawn in symbols for valves on process flow sheets, turned them on and off in plants, and taken quite a few apart without really thinking about how they work or the subtle effects of their designs. Valves, of course, are devices to close off and regulate the flow of fluids in pipes and from vessels.
Many types have evolved over the years to cope with various pressures, suspended solids, and economics of fabrication, and to ensure ease of use and convenience of maintenance. Most valve designs have at least one wear part, usually some form of polymer seal or gasket, which is designed to conform against a metal seat when a stem is moved up or down. Other types, such as ball, plug, and butterfly have movable parts that can block off or provide an open passage for fluids.
Dairy processing involves the movement and control of several fluids, some of which are vulnerable to microbial contamination, such as fluid milk, cream, and ice cream mix. Dairies are also major users of clean-in-place (CIP) practices, in which caustic and acid solutions are circulated through equipment and pipes to clean them, mostly automatically. Time spent cleaning is unproductive, and so there is motivation to minimize it.
On the other hand, milk and other dairy products are potentially hazardous to public health if not properly processed and protected from contamination. Milk processing is more heavily regulated than most other kinds of food and beverage processing, typically by laws based on the pasteurized milk order (PMO), a model law adopted by most states. Most dairy equipment is manufactured to 3-A standards, set by a voluntary industry committee. The PMO and 3-A standards have influenced the design of valves for use in dairies.
One major concern was the possibility that a seal in a valve separating milk from a line containing cleaning solution could fail and cause contamination. A common solution is to have two separate valves. Rather than leave the space between two valves closed off, the common arrangement is to have a third valve to allow that space to be drained. The drain is left open so that if a seal does leak, it will be obvious. This arrangement is known as “double block and bleed” and is common in other process industries, as well. Sometimes its purpose is to permit isolation for maintenance of a control valve or other device.
To reduce costs and space, the double block and bleed concept has been incorporated into single, but sophisticated, devices, which combine two valve seats and seals, independent actuators, sensors for valve seat position, and provision for cleaning all parts of the fluid contact areas. Typically, the valves use compressed air to open and springs to close, so that they are fail-safe. (Selection of the spring strength is part of the specifying engineer’s responsibility, as it has to be strong enough to resist possible pressure surges in the piping system, which might occur when a pump starts, for instance.) In one approach, valve seats are “stroked” (opened and closed several times) during CIP. However, this means that only a single seal protects the product, so it has been required to shut down product transfers while the valves were cleaned.
At the IFT Food Expo®, GEA Tuchenhagen Flow Components, Portland, Maine, was showing a 24/7 PMO Valve that they say removes this requirement and thus can add some productive time to a dairy’s schedule. Sanitary valves come in 2-, 3-, and 4-way configurations and with special designs for tank bottoms and for horizontal mounting. It is common in dairies to have matrices of valves permitting flexible connections among multiple tanks and multiple fillers, freezers, CIP supply, and CIP return. These matrices are often installed at floor level for easy access.
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More From the Expo Floor
Here’s a look at some of the other technologies and equipment offerings that were on display at the Expo, broken out by category.
• Drying. Two processes based on drying with microwave energy in a vacuum chamber were in the spotlight at the EnWave Corp. booth. “nutraREV” is applied to pieces, such as berries and mushrooms, while “powderREV” is a continuous process for powders, including cultures, nutraceuticals, and enzymes. Representatives of the company, which is based in Vancouver, British Columbia, claim quality comparable to freeze drying but say that the process is much faster and less expensive.
Innovative Foods CEO Ed Hirschberg,an old friend, applies infra-red freeze drying to almost anything he can find. (Don’t stand still too long at his booth.) His South San Francisco, Calif.-based company is looking to extract values, such as functional flavors and ingredients, from food processing wastes, and has turned cakes, sandwiches, and soups into shelf-stable snacks.
Sono-Tek Corp., Milton, N.Y., offers ultrasonic atomizing nozzles for lab-scale spray drying. Flow rates can be as low as 1 ml/hr and up to 1 L/hr.
NIZO Food Research B.V., Ede, The Netherlands, is an independent research center in Europe with a pilot plant and a particular interest in modeling and improvement of drying processes.
CPM Wolverine Proctor, Horsham, Pa., now also owns Lauhoff, provider of dry corn milling equipment as well as flaking mills. The company has a full line of food dryers, as does Aeroglide, Raleigh, N.C., maker of National, FEC, and Sargent dryers. LCI, Charlotte, N.C. (formerly Luwa), offers a range of wiped-film equipment for evaporation and drying.
Reading Bakery Systems, Sinking Spring, Pa., has a Science & Innovation Center with a wide range of baking equipment–including mixers, a former, and ovens–available for use in product development. Reading is especially known for pretzel processing equipment, but the center can make almost any baked snack.
• Small-scale Equipment. Orchard Park, N.Y.-based Goodnature showed two integrated pasteurizers and their Squeeze-box Press. The presses can handle 1.25–2.5 tons/hr (without press aids) and twice those quantities with press aids. This gives up to 1,000 gal of very clear juice in high yield. The clever feature is how the press unloads the dry cake by lifting the press chambers and rotating to dump the cake. The pasteurizers can handle 20–30 gal/min.
Glatt, Weimar, Germany, offers a lab-scale granulator holding up to 3 kg with a spraying rate of liquid of up to 2 kg/hr.
Creative Research Management (CRM), Stockton, Calif., uses an aseptic system from MicroThermics, Raleigh, N.C., for custom manufacturing of food ingredients as well as for preparation of its own proprietary products.
Armfield Ltd., Jackson, N.J., introduced a HTST/UHT mini pilot system featuring bag-in-box filling capability and a new counter-pressure filling station for carbonated beverages.
Another carbonator and filler was shown by OMVE Netherlands B.V., Schalkwijk, The Netherlands. Armfield’s unit can do 60 L/hr, while the OMVE unit can do 25 L/hr (50 x 0.5 L bottles).
OMVE also offers a cold plasma demonstrator. This is intended for lab-scale determination of inactivation kinetics using plasma generated by electricity in nitrogen or helium. It uses 300 L/hr of gas.
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Bottom Line Process Technologies Inc., Largo, Fla., manufactures mini and small-scale winnowers for roasted or raw cocoa beans, suitable for labs or artisanal processors. Capacities are 15–150 kg/hr. Beans are broken, nibs and shells separated, and nibs screened.
Zoatec GmbH, Neuenburg am Rhein, Germany, offers a packaged vacuum processing and homogenizing vessel that comes in capacities from 4–10 L up to 1,890–5,000 L. It is used to make viscous foods such as sauces, ketchup, jams, and concentrated soups.
• Mixing and Extrusion. A division of AZO, Amixon, Memphis, Tenn., offers a selection of vertical axis mixers with easy access to the inside through side doors, highly polished finishes, and the ability to handle dry mixes as well as pastes.
American Process Systems, Gurnee, Ill., showed a high-velocity paddle mixer that the company claims can greatly shorten mixing times. This saves energy and increases production rate with, the company reports, no product degradation, obviously dependent on specific materials.
Bühler AG, Uzwil, Switzerland, discussed a two-stage conditioner, which prepares feed to an extruder. The concept is to do more of the cooking in the relatively less expensive preconditioner compared with the extruder, thus reducing the energy consumption of the extruder. Bühler was also involved in one of the novel processes presented at a New Products and Technologies session—nut pasteurization using steam at 0.5 bar for 5 min, then 5 min under reduced pressure (0.1 bar) to dry the nuts. The company claims 5-log reduction in pathogens. Bühler cooperated with Barth in the process development, and the process is evidently offered in the United States by Koco Food Tech, Phoenix, Md., a supplier of equipment to the nut and confectionery industries.
Andy Rao, professor emeritus of food science at Cornell University, gave the Food Engineering Division lecture on fibrils from proteins. He reviewed sophisticated research using whey proteins as models to understand the conditions of time, temperature, and pH that influence formation of distinctly unique forms that might give insight into diseases such as Alzheimer’s and also may have commercial value as drug delivery vehicles.
Processing Exhibits to Increase Next Year
IFT and the Food Processing Suppliers Association (FPSA) announced at the Annual Meeting & Food Expo that the IFT Food Expo and the FPSA Process Expo will be co-located at McCormick Place in Chicago in 2010. Sounds like more work for this reporter, but it’s exciting news for the food engineering community.
J. Peter Clark is Contributing Editor, Food Technology ([email protected]).