Vacuum systems provide suitable vacuum conditions for decolourization and deodorization in edible oil refineries. Both are highly critical processes, and a stable and reliable vacuum system plays a crucial role in ensuring high-quality outcomes.
The temperatures required for an effective decolourization process range from 105℃ to 110℃, while for deodorization they range from 240℃ to 265℃. Oil contains a little oxygen, and at these high temperatures, this causes the oil to get oxidized. Oxidation renders oil unusable, rancid with high fatty acid content. However, vacuum conditions prevent oil from being oxidized at high temperatures.
In a batch refinery plant, the deodorizer removes odours and free fatty acids that have been neutralized through alkalization. However, in a continuous refinery, free fatty acids and odours are removed in the deodorizing tower resulting in a better quality product. Reducing the boiling point at vacuum conditions makes it easier for volatile materials to be carried away by steam and deliver better deacidification and deodorization.
Choosing the right vacuum pump for your edible oil refinery: The degree of vacuum required depends on the quality of the crude oil and the end-product specifications. Therefore, your process engineering partner will seek this information from you before recommending vacuum pump specs for your edible oil refinery.
Components of a vacuum system: A basic vacuum system consists of three parts - a nozzle, a mixing chamber and a diffuser.
The nozzle discharges a high-velocity steam ejector across a suction chamber connected to the equipment being evacuated. Process vapours are drawn along with the steam jet into a Venturi shaped diffuser, which converts the steam's velocity energy into pressure energy, ultimately enabling discharge to the atmosphere.
Ejectors are of four types - single-stage, multi-stage condensing, multi-stage non-condensing and multi-stage with both condensing and non-condensing.
Lower suction pressure is obtained by the staging of the ejectors, and the number of stages depends on the suction pressure needed.
Maintaining your vacuum system to bring about longevity:
There are some basic preventative steps you can take to ensure the longevity of your vacuum system. All of these actions, however, must be carried out in line with the operating instructions in the user manual your technology partner has provided.
- System leakage: Joints must be leak proof to achieve the desired pressure. Hydraulic and pneumatic tests should be conducted twice a year. Hydraulic tests check for leakages in the system by filling it up with water at high pressure. Pneumatic tests check for air pressure and leaks. These checks address leaks that may have sprung in the pump section, flanges connecting the pipeline or the inspection glasses.
- Water temperature: Cooling towers should be maintained regularly. Water supplied to the vacuum system comes from the cooling tower at 32℃. It is stored in the cooling tower, brought to the desired temperature and then circulated through the vacuum system. Ensure that water temperature in the cooling tower is always maintained at desired levels, or it can result in a failure of the cooling tower.
- Steam quality: If the steam generated has a higher moisture content, desired results will not be achieved - you can check your boiler to correct this
- Steam condensing: Clean out the nozzles twice a year during routine maintenance. Check the status of the condenser, the flow and that the baffles are in good working order.
- Blockages: Check for any blockages in the fins and fans.
- Electrical and Mechanical parts: Electrical and mechanical parts should be checked daily.
Apart from basic preventative maintenance, please get in touch with your technology partner if your vacuum system is not performing as expected.
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