Separator RSE / RSI for Edible Oil Refining

During crushing the crude oil is obtained from the original feedstock. Seeds are usually pressed while beans require extraction to separate the oil from the rest. Examples for seed oils are canola and sunflower, a typical oil bean is soy. Pressed oils are clarified in a decanter stage before the gums are removed by water degumming.

Feedstock: all oil types that are pressed, i.e. rapeseed or sunflower.

What to consider:

• Solids content > 3 Vol.%
• Adding water before entering the decanter improves clarification results, oil quality and yield.

Benefits:

• Fully automatic, no intervention or optimization needed by operator
• Closed process: clean product, clean production
• Very small footprint
• Easy maintenance and service 

Feedstock: all oil types, beans or seeds, from pressing or extraction

What to consider:

• Standard process stage in the crushing plant to remove hydratable phospholipids (HP) from the pressed or extracted oil
• The degummed oil is either directly conveyed to refining or has to be dried in a vacuum if it is stored or sold

Benefits:

• Recovery of lecithin possible as an additional valuable by-product
• No tank bottoms in storage tanks
• Less oil losses in the following refining stages

... free fatty acids don't stand a chance. The caustic soda added to the crude oil reacts with the FFAs to form sodium soaps. Centrifugal separators then remove the soaps from the crude oil. The neutral oil is subsequently bleached and deodorized. This method can be used for reliably refining virtually all crude oils, including oils of low quality, with the exception of castor oil.

The standard neutralization process is called exactly this, Standard Neutralization. It is the most common method to neutralize pre-degummed oils or oils with only a low phosphatide content. 

Feedstock: Virtually all oils, including and especially low quality oils, except castor oil.

What to consider:

• In order to condition the NHPs (non-hydratable phosphatides), a small quantity of concentrated phosphoric acid is added and intensively mixed with the oil. Only then neutralization takes place by adding caustic soda. 
• Crude oils with a relatively high phosphatide content require a reaction tank after mixing, oils with lower phosphatide contents can be conveyed directly to the first separator that removes the sodium soaps.
• After the first separator stage the residual soap content in the neutralized oil is still too high for subsequent process stages. So a washing stage is required, in most cases one stage will suffice. 
• Cottonseed oil is the only exception here: in order to eliminate most of the gossypol we recommend a second caustic treatment. Cottonseed oil should always be neutralized in 3-stage installations.

Benefits: 

• Most reliable process, also and especially for low-quality oils
• Better oil quality than with physical refining
• All oils except castor oil can be processed

Feedstock: for oils that contain waxes and have relatively low FFA contents, e.g. sunflower oil

What to consider

• The oil's residence time in the crystallizers is several hours
• Before removing the soapstock in the separator the crude oil has to be gently heated to reduce viscosity
• Also in cold refining an additional washing stage is required

Benefits:

• Effective removal of FFAs and waxes
• Compact installation

In physical refining the free fatty acids are removed by distillation in one stage during deodorizing. This method requires lower investment and is simpler in installation and operation compared to chemical refining. However, crude oils that are refined physically have to be degummed as far as possible because residual gums affect the oil quality during the extensive heat treatment in distillation. For some oil qualities this is only possible to a limited extend. Other oils, i.e. cottonseed or fish oil, are fundamentally not suitable for physical refining.

The crude oils from the crushing plants still contain high amounts of phospholipids. They have to be removed as they harm the oil's storage stability as well as further processing. Some phospholipids can be hydrated (HP), some cannot (NHP). Most of the HPs have already been removed during water degumming. Thus, the degumming stage in physical refining attends to the NHPs. There are myriad of possibilities to engineer a degumming stage, the actual realization usually depends on customer preferences and oil type and quality respectively. In general, we recommend either TOP or cold degumming (aka dewaxing). Why? Read on, please.

The crude oils from the crushing planst still contain high amounts of phospholipids. They have to be removed as they harm the oil's storage stability as well as further processing. Some phospholipids can be hydrated (HP), some cannot (NHP). Most of the HPs have already been removed during water degumming. Thus, the degumming stage in physical refining attends to the NHPs. There are myriad of possibilities to engineer a degumming stage, the actual realization usually depends on customer preferences and oil type and quality respectively. In general, we recommend either TOP or cold degumming (aka dewaxing). Why? Read on, please.

What is so top about TOP degumming is that it is the only degumming method without waste water.

Feedstock: all oil types that do not contain waxes

What to consider: 

Have we mentioned that this is the only degumming method that does not produce waste water? Well, it does incur of course, at least to some extend, but we have set up the process in such a way that the water is constantly recycled. 

Benefits:

• No waste water
• No dealing with waste water high on BOD and COD
• Extremely short retention times of only 6 minutes which is perfect for anyone who processes different raw materials
• Oil losses are extremely low or oil yields are very high - depends on how you prefer to look at it
• HPs and NHPs are reliably and effectively removed
• Small footprint - you don't need lots of space to profit from all those benefits