When beer is bottled, its residual oxygen content must be kept as low as possible. To this end, breweries employ two different methods, either singly or in combination:
Bottles are flushed with CO2 and filled with beer via a long-tube filler. In this case, the filler tube is inserted into the bottle and the bottle is flushed with carbon dioxide before actually being filled with beer. This method consumes a relatively large amount of CO2.
Bottles are evacuated and then flushed with CO2. This method greatly reduces carbon dioxide consumption because most of the oxygen is already extracted.
By reducing seal liquid consumption, L-Series circulation systems offer clear advantages over other liquid ring pumps.
During the production of chocolate eggs, vacuum is used in several production sections to hold the eggs in place and lift them up. The vacuum system is installed in a separate room and sucks the air-conditioned air from the production line. The vacuum at the machine is maintained at a constant pressure.
Vegetables are air-dried after washing. Sensitive vegetables are cleaned with compressed air only.
The coffee beans are whirled around while being roasted to achieve a constant roasting result.
On yoghurt filling machines the vacuum pump serves to position the lids on five pre-filled yoghurt containers simultaneously. Suction cups on the machine grip the lids, separate them and move them into the correct positions.
Mineral water from natural springs contains carbonic acid, minerals and iron. The iron dissolved in the water oxidizes when it comes into contact with the air, giving the water an unpleasant taste. The water needs to be deferrized at a pressure of about 50 mbar, but first a vacuum pump is required to remove the carbonation and then reintroduce it to produce sparkling water.
Prolonged exposure to air gives salad oils and fats an unpleasant odour and flavour. Before they can be processed further, these oxidation products must be removed. This is accomplished by injecting steam, which absorbs the odour and flavour particles created, and then extracting the steam with a vacuum.
The packaging process has numerous requirements for vacuum pumps, as during evacuation of only air, but also water vapour, fat and spice mixtures are evacuated. Because of higher requirements for quality of food with regard to flavour, colour, homogeneity and durability, meat processing uses more and more vacuum, too, e.g. in Filling machines, Tumbler machines and Cutter machines.
Filtration units are used for filtering and cleaning liquids. The choice of the filtration membrane (nano-, ultra- or microfiltration) depends on the product requirements. Crossflow filtration, for example, involves re-circulation of the feed stream across the membrane surface caused by the pressure difference between retentate and permeate. During the filtration process, particles deposit on the membrane surface which are gradually removed by the cross flow velocity generated by the pump to minimise polarisation.
Fruits, vegetables and their subsequent products, such as mash and purée, are preserved through cooking. This involves heating a small amount of water to generate steam which removes the air. To obtain a high product quality and energy efficiency, the preservation process is carried out under vacuum.
To prevent fruits from maturing, they are stored in cooling chambers under so-called controlled atmosphere conditions: after having been exhausted, the cooling chamber is filled with inert gas. Alternatively, the inert gas is carefully compressed into the packaging.
Today you will rarely find ham that has been dried and smoked in a genuine fireplace. Instead, ham is soaked in a curing solution, which penetrates the meat more quickly and directly after the air is extracted from the pores.
Tobacco packed in bales is so brittle that without proper humidification it would crumble into dust when processed further. A vacuum pump extracts the air from the bales and replaces it with steam, sometimes supplemented with aromatic substances.
In addition to transporting the milk, the vacuum used in milking systems performs other tasks as well, such as attaching onto the udder and holding the weight of the milking claw assembly to the teat. Liquid ring pumps and side channel blowers offer significant advantages over traditional oil-lubricated pumps because they use no oil. The side channel technology has the addtional advantage of requiring no water connection - and it is optionally available with frequency converters.
Fresh air is pumped into the warehouses to aerate the potatoes.
Even the weighing and portioning of foods produces waste products that must be disposed of quickly and automatically. A weigh station for chicken breast fillets, in which individual portions are transported by belt weighers and sorted into weight groups, produces liquid waste as well as fat and small fibers. A vacuum pump extracts this waste and passes it on for proper disposal.
The food industry employs processes similar to those described above to automatically extract the entrails from salmon. Operating at a rate of only 3 seconds per fish, the quantity of material to be processed is enormous. The resulting waste products consisting of saltwater, fats, proteins and fish remains are extracted by means of a gas ring blower located beside the salmon cleaning machine.
To produce sausages a meat mixture is chopped into small pieces and mixed with spices and other additives. Extracting air during the chopping and mixing processes can help prevent the mixture from oxidizing, which would have a negative effect on the sausage's flavour and appearance. The air is evacuated by means of a vacuum of about 100 mbar. The pump used must be insensitive to the meat particles and liquids that are also extracted.
Tea and spices imported from tropical regions are shipped in bales, which very often contain pests, insects, fungi and bacteria that must be destroyed before further processing can occur. This is done by placing the bales in vacuum containers and extracting the air. The bales are then injected with steam or a sterilized gas.
A mild acid extracts the saccharose from the sugar canes which is then cooked to produce sugar syrup. To reduce energy consumption, both cooking as well as the subsequent crystallization process are carried out under vacuum.
Before any further processing can take place, fish and molluscs must be gutted and cleaned. Worktables are outfitted with suitable vacuum nozzles that extract the entrails from the fish. A central vacuum system then pipes the combination of liquid and coarse particles through a filter where they are separated for proper disposal.
Elmo Rietschle is part of Gardner Denver, Inc., a leading global manufacturer of highly engineered products. Gardner Denver is headquartered in Milwaukee, Wisconsin, USA and has facilities in more than 30 countries.
To learn more about Gardner Denver, Inc., please visit www.gardnerdenver.com.