When Southern Gardens Processing Corp. recently built a citrus processing plant in Clewiston, FL, it was Florida's first new orange juice processing plant in nearly two decades. A key issue for the plant's design was its insulation, needed to protect refrigerated fluid streams. The insulation has to stand up to highly humid weather conditions, as well as the corrosive effects of citrus oils. To address these problems, the plant designers specified Foamglas insulation, from Pittsburgh Corning Corp.
Southern Gardens is a United States Sugar Corp. company. U.S. Sugar is one of the nation's leading agricultural companies and is among the largest producers of raw sugar and is a major grower and marketer of citrus. The first phase of construction on the facility began in 1992, and its grand opening was in early 1994. Total cost for the first phase of construction, including the infrastructure for future expansions, was approximately $40 million.
In its first phase, the plant was designed to process 45,000 boxes of oranges per day, or approximately 86 trailer loads of oranges. This production yields about 41,000 gal of concentrated orange juice, or almost 300,000 gal of single-strength (not-from-concentrate) juice. These juice products are sold to be packaged for retail sale under familiar brand, private label and food service names. Additionally, the plant produces products that are used in the food, fragrance, electronics and agricultural industries.
From Orange to Juice--The Process
Oranges are delivered to Southern Gardens, then washed and mechanically de-stemmed. After passing state inspection, fruit proceeds for final washing and grading, is sorted by size, and enters the juice extractor line. Each of the plant's 20 juice extractors can process about 5 ton/h of oranges, separating the juice and pulp from the peel, seeds and membrane.
The juice is then directed to one of two possible paths. If it is to be sold as single-strength, it passes through a pasteurization process and is quickly chilled. Juice to be sold as concentrate moves through evaporator units where water is removed. The concentrate, having by this time been reduced to 1/6 of its former volume, is then chilled. The plant, which runs on a 22-hour production day, can funnel both concentrate and single-strength juice simultaneously. After blending and cooling, the concentrated juice is transported through pipes to an enclosed tank farm. In the tank farm, three million gal of concentrate are stored in 16 tanks (187,000 gal each) and stored at a constant temperature of 18°F.
Foamglas Insulation Meets Unique Juice Processing Needs
The first construction phase included two buildings: (1) the frozen concentrate tank farm, and (2) the cold storage building for storing drums and packaging. Included in this initial phase were piping systems for more than 40 types of fluids and a number of stainless steel tanks ranging in size from 100 to 186,000 gal. In addition to process liquids, pipelines carry steam, condensate, glycol, refrigerants, oils, gas and more at temperatures ranging from 350°F to well below zero. The insulation specified for all the bases of the tanks and a number of pipeline applications was Foamglas cellular glass insulation, manufactured by Pittsburgh Corning Corporation.
According to Roland Young, P.E., who was Director of Mechanical Engineering for HWH Architects-Engineers-Planners, Inc. in Orlando, Fla., the piping insulation selected was critical to the long-term success of the system. HWH is the firm that was commissioned to design the entire plant, including all mechanical piping systems during the first phase of construction.
Fig. 1. FOAMGLAS cellular glass insulation products and systems have been used for a wide range of applications at virtually all operating temperatures, including chilled water, cold processing, ambient and above, tank, steam and roofing. Impermeable to moisture in liquid or vapor form, FOAMGLAS insulation provides constant thermal efficiency and will not promote corrosion.
"Foamglas insulation was specified for the cold piping applications carrying juice and concentrate because of its imperviousness to moisture-regardless of whether its vapor barrier finish gets damaged or not in the course of day-to-day operations," says Young. The piping systems carrying cold fluids operate in most areas of the plant in ventilated-only environments. As a result, the piping systems operate in the high South Florida ambient humidity, which often approaches 100 percent.
This moisture resistance is critical to the insulation's long-term performance. Any piping that carries fluids below 32°F are susceptible to ice formation from ambient humidity. If this ice forms below the insulation, it can damage the insulation and eventually cause the piping to fail. Both low-temperature and high-temperature piping is exposed to outdoor ambient air at the plant; these streams include steam, condensate, ammonia refrigerant and glycol. The cellular glass insulation performs well under these diverse conditions. "Other types of insulation with perhaps lower initial costs did not have the performance capability of Foamglas," he concludes.
If an insulation or pipeline failure were to occur, it would drastically reduce operating efficiency and process control, and increase energy costs. Additionally, it can lead to severe corrosion problems, costly repairs and plant shut-downs.
Insulating Tanks for The Second Phase
An expansion phase began at Southern Gardens in April 1995 to increase capacity to more than 20 million boxes of oranges, or 120 million gal/yr of juice. The second phase was completed in late 1995, and additional expansions have been planned for the next several years.
Included in this second phase was the construction of an enclosed, 8-million-gal, single-strength juice tank farm which was completed late in 1995, measuring more than 28,000 sq. ft. A total of eight tanks (60 ft. tall, and 53 ft. in diameter) were built, and, once again, the insulation selected for all bases of the tanks was Foamglas cellular glass insulation.
Fig. 2. Each tank is supported by concrete and two three-inch layers of FOAMGLAS insulation.
Each tank is supported by a concrete sub-slab, two three-inch layers of Foamglas insulation, another concrete slab and a raised concrete foundation upon which the tank rests.
According to Stuart Salter, who was Vice President and General Manager of Southern Gardens when the installation took place, Foamglas insulation was chosen because it best met the plant's needs for strength and resistance to citrus acids. "We specified Foamglas insulation because it is impervious to citrus oil and has a tremendous capacity to support weight," he says. "This is critical due to the destructive nature of citrus oil, which can destroy unprotected polystyrene."
Polystyrene and polyurethane insulation may compact or deform as much as 10 percent before developing full, published compressive strength, which may cause cracking of the concrete-slab floor. Citrus acid spills then may enter any cracks in the concrete floor and dissolve the polystyrene, creating even more damage. As with piping applications, insulation and system failure can be quite expensive to repair and can interrupt the manufacturing process.
"I've seen first-hand how citrus oil destroys unprotected plastic foams," says Salter. "It's just like pouring on lighter fluid-it just eats away at the material. Although polystyrene may be OK for wall applications, it just doesn't work if there is any likelihood that citrus oil will can get to the insulation. Even if everything is installed properly, cracks appear over time and the insulation will fail, causing a void between the concrete slabs and uneven settling of the tanks."
High compressive strength
Southern Gardens Citrus selected Foamglas insulation because of its unique blend of physical characteristics, which is important to the food and juice processing industry. Foamglas insulation combines excellent thermal performance, impermeability to liquid and vapor, noncombustibility and the highest compressive strength of any commonly used floor insulation.
"We specified Foamglas insulation because of its long-term performance," explained Salter. "It may cost more initially, but the value received more than justifies the extra cost because of its increased reliability and the fact that it is completely unaffected by citrus oil if it comes into contact. And in the real world, someday, at some point, it more than likely will."
Edited by Nick Basta