This process above can be either continuous or batch mode. The process consists of five separation steps: first reactor, second reactor, decanter, flash distillation column, and adsorption column. This new process to be able to produce glycerol higher than 99.5% purity from typical crude glycerol.
The crude glycerol is preheated first before heading for the first reactor. The purpose of the first reactor is by reacting glycerol and methyl esters to produce methanol and glycerides. The water and methanol removed when nitrogen is sparged. The gas runoff stream is passed through a condenser. The nitrogen is recycled back to the reactor when water and methanol are condensed (separated) through a condenser.
The purpose of this reactor is that the unreacted methyl esters are reacted to produce triglycerides and methanol. Wash water has glycerol, is also added to the 2nd reactor. From the 1st reactor the liquid effulent stream is heated to preserve the 2nd reactor at 120-160oc just like the 1st reactor. Wash water is recycled when water and methanol is separated from nitrogen.
The purpose of decanter placed after the reactor is to get rid of the oil layer from glycerol stream by reducing the pH below 7 and also skimming it from the glycerol layer. In this tank glycerol stream is mixed with the recycled stream from the bottom of the flash column.
Flash distillation column:
In the flash distillation, the top column (vapour fraction) product is about 80-90% of glycerol from the feed stream is to be condensing in two condensers in series. Condensing glycerol is used in the first condenser whereas water condensing used in the 2nd condenser that will be sent to waster water stream. The heavy compounds and glycerol comes out of the bottom product (liquid fraction) is pumped back to the decanter. To prevent glycerol and salts build up in the decanter, some of is purged.
Removing the trace impurities and colour is the last step of glycerol refining. Ion exchange resins and activated carbon can be used as adsorbent material. Glycerol is then purified into a storage tank.