Processing, June 2019

JUNE 2019 www processingmagazine com 29 rowing citrus has many challenges as does processing the fruit Nonetheless in the state of Florida its a 9 billion industry with 600000 acres dedicated to citrus groves supporting about 74 million trees Altogether 76000 people in the state are engaged in all phases of citrus production This population includes Southern Gardens Citrus a grower processor based in Clewiston Florida Southern Gardens Citrus is a worldwide supplier of premium not from concentrate NFC Florida orange juice as well as orange by products The Southern Gardens Citrus processing plant was built in 1994 and is capable of processing up to 180 million pounds of oranges a year The facility can store 56 million gallons aseptically and ship and receive more than 100000 tankers annually Like others in this industry segment Southern Gardens Citrus must deal with problems such as citrus greening disease international competition and the inefficiencies that come with an aging plant while staying as profitable as possible Its facility in Clewiston while still the newest of its kind in Florida is 25 years old Juice and more Oranges and grapefruit are far more versatile fruits than most people realize Juice is the primary product but little of the whole fruit goes to waste Once the juice is extracted Figure 1 the peels are squeezed to produce a liquor which can be made into citrus molasses for use in distilleries and even as cleaning products The solids from the peel and pulp can also be dried pelletized and sold as cattle feed This article will focus on making orange juice concentrate To produce concentrate fresh juice is put into an evaporator where much of the water is removed until the specific gravity is raised to 65 Brix so it is very viscous Storing the concentrate takes place in a special building within the facility where 16 tanks stand close together connected by catwalks Figure 2 Each tank is 32 feet in diameter by 32 feet tall with a capacity of 186514 gallons All images on this page courtesy of Southern Gardens Citrus The building is a huge freezer Florida is known for its heat and humidity but the temperature inside this building is a frigid 16 F 9 C with a lot of internal air movement Maintaining this environment allows the product to cool rapidly in the tanks with no internal cooling coils or jackets required And even with a product this viscous foam can be created so the product movement has to be handled carefully with all filling and emptying processes from the bottom The tanks cycle through filling and emptying cycles one by one so there is activity in the freezer room on a daily basis This is where all the concentrate inventory is stored so it has to be monitored carefully to determine how much product is in each tank Monitoring concentrate inventory When first built Southern Gardens Citrus tanks were fitted with ultrasonic acoustic level instruments designed to determine the level in each tank reading from mounts on the tank roofs These instruments proved to be temperamental and were removed from service Operators had to check the tank levels on a daily basis by hand using manual measuring devices While the idea of going inside a freezer on a hot day in south Florida might have some appeal the novelty wears off quickly when it takes up to 30 minutes to check just one tank while working in the bone chilling temperatures Parkas and gloves are the uniform and none of the operators necessarily like getting tasked with the job It is also clear that checking 16 tanks daily required eight hours so the plant spent as much as 56 manhours per week on nothing but checking inventory in these concentrate tanks Considering that plant operators are in short supply nationwide telling a prospective employee that he or she will spend many hours in a freezer makes the job even more challenging to attract and retain operators Southern Gardens Citrus is a highly automated plant so the notion of having to perform this routine level measurement task manually every day seemed a wasteful misuse of human resources Unfortunately the negative experience with the earlier measurement technology left an impression that meant any new solution would have to prove itself capable of solving several critical challenges including Deliver continuous readings that are precise enough at all product levels to satisfy production and financial planners Perform flawlessly in the constant low temperature environment of the freezer building See through any layer of foam to determine the true product level Eliminate any reason for operators to enter the freezer building related to level measurement Finding the solution After studying Southern Gardens Citrus application Emerson engineers suggested the Rosemount 5402 Non Contact Radar Level Instrument Figure 3 On paper it had the right specifications for measurement precision and maximum distance and the electronic elements were rated for temperatures down to 40 F 40 C It could even be mounted using the flanged spuds on top of the tanks originally designed for the earlier ultrasonic instruments so no tank modifications would be necessary But one question would have to be answered Would it work as well in real life as the specs promised The first question related to foam The concentrate coming out of the evaporators is viscous but still flows easily prior to cooling It is also prone to foaming As a result all connections to the concentrate tanks are from the bottom to eliminate any splashing Still there can be a layer of foam on top that forms during filling and tends to freeze The foam surface G Figure 1 Extracting juice is fully automated and the lines run continuously Figure 2 Operators can walk around the freezer building above the tanks on a network of catwalks but it is close to the air handling equipment and very cold Figure 3 The new radar instrument bolted in place using the existing flanged spuds