Juice Flotation |
Velo 30,000 litre per hour batch units
Flotation involves the implosion of micro-bubbles of food grade nitrogen into wine juice under pressure. As the gas rises to the surface suspended solids adhere to the surface of the bubbles which are skimmed off the wine. The procedure has several advantages over other clarification techniques,notably control over the degree of clarification desired. In addition it can be used as a pre-treatment to improve the efficiency of other procedures such as crossflow filtration.
This device does away with the dedicated flotation tanks as well as the need for rotation top-suction equipment to remove the flocculated and floating juice solids. Instead, the juice is pumped into the Velo where it is pressurized and dosed with a fining (flocculation) agent like bentonite or bentonite/gelatine. The treated juice is then pumped to a second tank where the floc is allowed to form and float to the surface. The clarified juice is then pumped out from underneath the flocculate. Since, unlike centrifugation, the juice solids are not diluted with water in this process, the juice solids can be further filtered for additional juice recovery.
Vintech Pacific now has two of these portable Velo Juice Flotation units capable of handling 30,000 litres of juice per hour.
MODEL PFC 300: The discontinuous flotation unit allows for the clarification of must in a simple way – fast and without the necessity of bulky plant.
The unit comprises:
The plant is built on a frame with wheels. On the same cart is the electric control board and the pneumatic control board.
The electric board incudes a main switch, pressurisation pump switch, an electro-valve switch for the dosing of the compressed gas.
The pneumatic board includes a pressure reduction regulator for the compressed gas with oil filter, electro-valve for air dosing and connection for “Turbo-Shacker”.
The Italian winery equipment manufacturer Velo has been making filtration equipment for several years.
Flotation is a process for removing suspended solids from a liquid. Flotation, like cold settling of juice, exploits density differences between solid particles and the surrounding liquid. In cold settling, the solids precipitate out because they are denser than the liquid.
In flotation, however, instead of simply relying on relative density and time to "settle-out" suspended solids, it exploits the tendency of a dissolved gas to form bubbles on, and adhere to, suspended solids as the gas comes out of solution, with solids rising upward through a buoyancy gained by the adhesion of tiny bubbles of gas.
In order to get this effervescence, the juice is saturated with gas while under about five bars of pressure. Since the process depends upon the physical, rather than chemical, properties of a gas, pretty much any gas can be used. In the wine industry, the most common gases used are nitrogen and air. Nitrogen is used when oxidation of the juice/must is not desired. In the absence of free SO2 in the juice, air can be used as the flotation gas as well as the medium hyperoxidation of the juice.
In theory, however, one could use either carbon dioxide or argon for inert gas saturation. The relative affordability of nitrogen relative to argon and ease of handling relative to carbon dioxide means that nitrogen is essentially always used as the inert gas for this process.
Flotation turns "settling" on its head and, in effect, the solids hitch a ride on the gas and float to the top of the tank. Depending upon the exact equipment set-up, the solids can be skimmed off the top of the clarified juice, or the clarified juice can be racked out from underneath the solids.
As a technique, flotation has been around for quite a while. It's frequently used to remove solids from juices other than grapes. Additionally, the technique is quite common in the water-treatment industry.
Velo PFC 300 Flotation Unit connected to mixing tub, compressor, nitrogen generator and Wilden air pump.