In the maritime industry, innovation is often achieved through conversion and this is what happened in the development of MV Citrus Vita Brasil: The container ship MV Hermes Arrow, was converted into a combined juice tanker for not-from-concentrate (NFC) and for concentrate orange juice (FCOJ). Eight tanks are for dedicated solely to NFC and seven double-purpose tanks used for loading NFC and FCOJ. The new juice tanker, which is the length of two football fields, is capable of holding 7 million gallons of juice, equivalent to a capacity of 27,000 m³. The ship was a former container ship without cooling system. The old construction, used for accomodating containers, had to be removed along with the hatch covers. After inserting the new vertical stainless steel tanks into the insulated holds, an additional double bottom and new shelter deck were fitted and a new cooling system was installed.
Perfected Aseptic Tank Engineering
The stainless steel used for the tanks complies with the highest DIN standards. Moreover, the inner surface, meaning the complete inner tank welding, strictly conforms to ASME standards: 0.8 μm Ra and zero indication.
The ship’s cargo tanks are cylindrical units with vertical axes. The bottom of each tank slopes to a definite lower point; while the top is slightly conical. The pipework is connected to the lowest point to facilitate complete draining of the tanks. Propeller-type tank agitators ensure circulation of the tank contents when NFC orange juice is being carried.
Cargo pumps are installed at the bottom of the cargo hold between the cargo tanks. Frequency-controlled, electrically driven centrifugal pumps are used to handle the NFC orange juice, while a wider pipework system and a series of frequency-controlled, electrically driven positive displacement pumps support the FCOJ process. Radar level gauges determine how much product is in the tanks, and nitrogen pipes deliver nitrogen to fill the headspace in the tanks. Temperature sensors are used to monitor the cooling system.
A protective atmosphere of nitrogen is used in all tanks and pipework systems to assure the juice quality. The ship has an on-board nitrogen tank to provide a suitable buffer for maintaining appropriate levels in the tanks and pipework while at sea. Nitrogen is pumped into the tanks from a ship-based source when juice is discharged at the port.
Special diaphragm and sealing solutions are integrated into valves to ensure sterility. Larger valves which cannot be sealed with diaphragms are equipped with valve rod seals fit with alcohol reservoirs to support volume changes and wiping action on exposed sections of the valve. Flanges are designed according to the highest aseptic standards to eliminate cavities where bacteria could form. “This guarantees that the juice is not contaminated by harmful microorganisms”, explains Jurgen Stuijts, International Sales Manager Juice & Beverages at Ziemann Holvrieka.
Customized tank cleaning systems ensure aseptic conditions during cleaning and disinfection of the large tanks. Fresh water for cleaning and rinsing of the tanks is supplied via a separate fresh water tank installed in the forward part of the vessel. After cleaning, the empty tanks are filled with nitrogen to ensure sterility.
Customized Process Technology
All calculations and layouts were approved and released in advance by an independent classification society. This ensures that all components meet the high standards required for transport vessels in the juice industry. Only when a ship meets all specifications at the time of completion, it receives complete certification. Without it is not permitted to sail. Jurgen Stuijts describes the particular challenge posed during installation of the tanks: “Every ship is built differently, so the arrangement of load points varies. The tanks stand on a foundation which must be mounted exactly on these load points. The installation is therefore a tailored solution.”
Electrically driven refrigerant compressors were installed in the deckhouse. Brine from the evaporator room circulates through the heat exchangers in each hold, with large fans providing air to all parts of the insulated holds through strategically placed ductwork. Juice is loaded at the required temperature, and the refrigerating system has the capacity to maintain this temperature, no matter what ambient conditions are encountered during the voyage. The cooling capability of the equipment is 5° C to -10° C. The ship is also equipped with an emergency generator, designed to protect the cargo in the event of a electrical failure.
Additionally, state-of-the-art measuring and control technology, circulation pumps and discharge pumps were installed, along with a nitrogen system to provide a nitrogen gas cushion in the filled tanks above the cargo. A stand-alone CIP system was included in the process installation. A double piping system was installed for the combined transportation of NFC and FC orange juice.
In case of MV Citrus Vita Brasil, an additional request was for a development and construction timeframe of 10 months – and this target was met by Ziemann Holvrieka.
Reliable Support that Leads to Success
“Crew members receive a detailed training in advance to ensure that everything runs smoothly during filling, emptying and cleaning”, explains Jurgen Stuijts. Extremely specialized equipment must be operated properly and maintained to ensure that the product remains sterile. Any breakdown of processes or equipment could lead to contamination of the juice.
The automation of MV Citrus Vita Brasil is cutting edge to ensure correct processes and the required asepticism. Human error can be eliminated as a result of this automation system. In particular, electronically controlled processes for filling and emptying of the tanks have been improved to ensure the sterility of the end product.
The cargo system of the fruit juice carrier is equipped with clean-in-place and sterilize-in-place installations. Stainless steel pipe manifolds are used on board and on shore during loading and unloading of the ship. Food grade hoses connect the two manifolds. However, the piping manifolds and hoses must be sterilized before the product is pumped through them. Ziemann Holvrieka provides training for the crew to reduce the risk of contamination with microorganisms when sterilization is not realized properly.
Smooth Cooperation with a Happy End
“This was a unique project for us. Citrosuco’s experience in ship management combined with our know-how in the construction of special tanks ensures high quality,” explains Jurgen Stuijts. “Citrus Vita Brasil will provide greater transport capacity and greater flexibility in the distribution of orange juice to our customers to meet the demand of different markets,” said Mário Bavaresco Júnior, President of Citrosuco, in a statement.