Synthetic food grade lubricants in atomisers
paste to a dry powder solid. This is achieved by using a hot air stream to atomise the fluid and evaporate the water. Atomisers are used in the drying or dehydration of a number of food and dairy products including baby food, coffee, flavourings and soup mixes.
|What are atomisers?|
|How do they work?|
|How are they lubricated?|
|Reducing lubricant contamination risk|
|Demands on the lubricant|
|Field trial Shell Cassida Fluid HF|
|Food grade lubricant is essential|
|Field trial results|
Nozzle spray-dryers atomise by producing high pressure hot air streams in the atomiser chamber. The single-fluid spray nozzle allows more versatility in terms of positioning the spray's direction. Two-fluid spray nozzles are often used for more viscous or abrasive feeds and are able to produce the necessary additional atomisation to form smaller particles. Nozzles are generally used to spray-dry liquid feeds that contain a high percentage of fats such as dairy products. The versatility of the nozzles allow the particles to be spray-dried with a lower fat content than if they were dried in a rotary atomiser.
The rotary atomiser can accommodate high volumes and production rates. lts spinning wheel can reach more than 300 foot per second and generates a centrifugal force which disperses and atomises the liquid feed. The speed of the wheel is used to control the particle size.
Nozzle and rotary atomisers operate using a number of moving parts which come into close contact with the liquid feed being atomised. The different types of atomisers both feature an oil pump system, a feed pipe, an air heater and a drying chamber. The rotary atomiser features a gearbox and electric motor, which drives the spinning wheel.
Spray-drying is a continuous operation and atomisers are used to dry loads ranging from five kilograms to 80 tons per hour. The exacting demands placed on the atomiser are often intensified by companies running the machines twenty four hours a day, seven days a week, in a bid to meet production demand. This continuous operation means that machines must be well maintained and lubricated to minimise downtime.
Reducing lubricant contamination riskWorking closely with food Original Equipment Manufacturers (OEMs) such as Niro Denmark, Shell has developed lubricants which meet these demanding lubricant requirements while reducing the threat of contamination. Niro Denmark is part of the international GEA group which specialises in the development, design and engineering of liquid and powder-processing equipment and supplies the energy, environmental and process industries with spray dryers and coolers, fluid bed systems and membrane filtration systems.
Shell Cassida Fluid HF has been formulated using synthetic high performance poly alpha olefins (PAO) base fluids and specially selected additives, which increase oil life and cleanliness. A tasteless, odourless and colourless lubricant, Cassida is harmless if it accidentally comes into contact with food below the Food and Drug Administration's (FDA) maximum level of ten parts per million.
This lubricant provides excellent oxidation and thermal stability, high anti-corrosion and optimal anti-wear properties. lts synthetic PAO base means that it can be used to lubricate non-ferrous metals, such as those found in the atomiser's worm gear system. Cassida Fluid HF has been developed in accordance with industry standards and practices and meets DIN 51524 parts 2 and 3, DIN 51517 part 3, hydraulic oils levels HLP and HLVP and gear oil level CLP.
Shell identified the LCCPs and advised how Cassida Fluid HF could be used to reduce the risk of contamination. A Shell team, together with Niro's service engineer, conducted two field trials of Shell Cassida Fluid HF. The tests were carried out on two different atomiser gearboxes and included oil-monitoring and maintenance inspections of the machinery. Internal inspections of the gearbox were also carried out after the operation.
Shell Cassida Fluid HF exceeded the recommended oil change interval of 3,000 hours. After 7,000 hours there were no visual signs of wear on the gears or the oil pump system and the machine's internal components were as clean as when the trial had started. These performance properties ensured that maximum productivity was reached without compromise to food safety. Despite the superior performance of Cassida Fluid HF, Niro and Shell recommend that lubricants in the atomisers are still changed every 3,000 operation hours to ensure that they remain fit for purpose.
Following the field trials and the superior performance of Shell Cassida Fluid HF, Niro is reviewing its lubricant recommendations to customers and is reluctant to recommend the use of mineral-based lubricants or lubricants not supported by proven field or operational experience. Shell Cassida Fluid HF is now being placed at the top of Niro's food grade lubricant recommendation list and is used in Niro's atomisers around the world.
Food OEMs are continually working to develop and design machinery which can meet the industry's increasing operational demands. Part of this development includes working with experienced lubricant providers such as Shell, who can advise on lubricant applications and practices. This enables OEMs to improve machine lubrication and ensure increased levels of operational efficiency, food safety and quality.
For more information: FUCHS LUBRITECH GmbH