All About Oil Refining Process
Edible oil refinery industries are facing the biggest challenges and opportunities in decades. To stay competitive, refinery suppliers should bring more expediency in the refining of edible oil while achieving production goals.
1. Desalting and dewatering
The desalting process removes salt and other contaminants because they can be corrosive to the refining pipes. Then, water is removed before it is sent to distillation stage.
2. Atmospheric distillation
Molecules of crude oil are separated using distillation based on their molecular weights. The crude oil is heated in a tank with different temperatures at different heights. First, the oil is heated at the bottom of the tank with a temperature of 350-400 C, causing lighter molecules to vaporize.
Gasoline and the group of products called middle distillates are the finished products with the highest demands. However, the separation process still yields heavy distillates. Therefore, the heavy molecules need to go through conversion, which is then divided into 3 types: cracking, combining, and modifying. Cracking is the most common type, which involves breaking large molecules into smaller ones. It may use heat (thermal cracking) or fluid (such as hydrogen) and also the catalyst to speed up the process.
Treating is the process of removing substances that are corrosive or air polluting, especially sulfur and nitrogen. The most common method is hydroprocessing, where these substances are reacted with hydrogen at very high pressure and high temperature.
Market demands on low cost, high octane fuelled to a process called blending. In this process, high octane components are blended with lower octane to produce various blendstocks with different selling prices.
In the deodorization process, the edible oil goes through the high-temperature, high-vacuum steam distillation process to remove odoriferous and volatile materials. The deodorization process plays an important role in removing off-flavors from edible oil. It also removes free fatty acids (non-sterified) that are not removed by the early stages of the refining process.
Over the years, the deodorization process has greatly improved and has made the oil refining process more efficient leading to lower operating costs, high refined oil yield and better valorization of side streams.
Also known as dewaxing of edible oils, the winterization process refers to a thermo-mechanical process in which solid particles in the edible oil are crystallized under controlled climatic conditions. The next refining stage is a mechanical separation of the crystals. The dewaxing process is recommended for edible oils that show turbid characteristics below 5 degrees Celsius. Some of the edible oils that are put through the winterization process are cotton and sunflower seed oil.
By following above refining process, oil processing companies can control the quality of the oil products throughout the refining process and get a clear view of the end product right from start.