Glycerine

Abstract Glycerine is a coproduct of fat splitting (hydrolysis), soap making, and trans‐esterification of fats and oils. The history of glycerine and it's economics as an industrial chemical provides an introduction and the basic chemistry. Two distinct types of glycerol are processed, soap lye crudes, which contain significant levels of sodium chloride, and sweetwater crudes, which have little to no sodium chloride contamination present. Processing glycerol into high‐purity refined grades requires pretreatment steps followed by evaporation to concentrate the glycerol solution into crude glycerine. The removal of sodium chloride requires specialized equipment. Refining crude glycerine into finished USP‐grade glycerine requires distillation equipment, which operates under a high vacuum. The final step of the process is carbon adsorption. Storage of finished and unprocessed glycerine requires special considerations. The effect of processing on glycerine odor and color is critical to final product quality. Processing plants require special considerations in terms of layout, materials of construction, instruments and controls, and piping. Overall considerations in glycerine processing include physical properties; quality and testing, including grades and test methods; losses; and waste management. A discussion of glycerine uses and future considerations provides reference for the glycerine industry.