A lot of us are familiar with laboratory centrifuges, but industrial ones are a lot less common. They function on the same principle, in the sense that they spin at high speeds as a mechanism to separate liquids and solids. This is mainly applicable for filtering wastewater, though individual scenarios differ broadly.
For example, you can use a centrifuge to recycle water that was used to wash fruits and vegetables before and after peeling and slicing. Before peeling, the water is full of soil, stones, and any chemicals that the food was exposed to in the garden. After cutting, the main contaminant is starch. This type of centrifugal filtration is a crucial process in jam making, canneries, or potato crisp factories, for example.
Cleansing fruits and vegetables
Another popular use is separating fruit pulp from extracted liquids in the manufacture of wine, beer, syrups, or fruit juice. In both cases, fruit pulp and vegetable starch are organic, food grade products, so they can be re-used in subsequent manufacturing processes, or packaged and sold as separate products.
In the food industry, the focus is usually on harvesting recyclable water, while the target in other industries is extracting toxins so that the water can safely go down sewers and the solid can be dumped in a land fill. For this reason, industrial waste is drier than food waste, and the centrifugal tools and processes are different.
Past the water and into the oil
Oil Centrifuges can also be used to filter petroleum products, fuel and oil, removing water and ‘bio bugs’. Another popular use is pushing air or water at high speeds and pressures, as seen in vacuum cleaners, washing machines, pumps, rudders, propellers, and similar machinery. In filtration devices, they are sometimes used to create vacuum chambers.
The material used to make centrifugal equipment depends on its function. They generally need to be resistant to corrosion and rust. They have to be lightweight, to avoid dragging down the machine and impeding speed and motion. It helps if they are easy to clean, and can withstand heavy usage, because these are high rotation machines. Let’s look at some of the constituent materials for centrifugal equipment.
Heavy duty cast alloy
This mix of metals is used to build the casing of the centrifuge. It’s strong enough to encase the other parts of the machine and to keep all those moving parts safely contained, despite the potential bangs and dings of extreme speed spinning. It can also withstand the high temperatures generated when the machine is in operation, and it can handle the temperature differentials of any coolants or cold fluid that may pass through the machine for filtration.
Heavy Duty 304 Stainless Steel
This glossy material is used to mould the bowl or drum of the centrifuge. This is the portion of the machine that contains the liquid to be separated, and it works by spinning on a rotor at nearly 4,000 rpm. 304 stainless steel can handle all sorts of liquids from greasy cutting fluids to murky water filled with glass shards and metal fibres. It’s resistant to abrasion, so the foreign particles in wastewater can’t harms its gleaming surface, and it’s resistant to acid and rust, as well as mechanical damage if the drum bumps the sides of the machine. The drive shaft of a centrifuge is also built using 304 stainless steel.
316 Stainless Steel
For discharge tubes, this steel variant is preferred. The difference between 304 and 316 is in the constituent metals that form the alloy. 316 has more nickel and less chromium, as well as 2% of added molybdenum. This extra ingredient makes your 316 steel better at resisting heat, chemicals, and chloride corrosion. This makes 316 steel better for external parts that receive more exposure to the elements (or in this case, to oxygenated liquids) while 304 works better for relatively protected internal parts like rotary drums. The tubes are coated with tungsten carbide for additional protection.
Centrifugal equipment may seem like industrial machines that populate dingy factory floors, but they also contain a high level of technology. They are fitted with touchscreens that make them easier to operate. Machine operators can calibrate pressure gauges, inlet volumes, rotational speeds and much more. Touchscreens also allow them to monitor any potential mishaps in the equipment, reducing downtime, avoiding accidents, preventing damage, and extending the lifespan of your centrifugal equipment. Touchscreens work in collusion with audible alarms, motion sensors, and warning systems that trigger ‘sirens and flashing lights’.