Natural crude glycerin can come from many sources, including fat splitting (hydrolysis of fat), saponification (adding caustic soda to fat as part of the neutralization process), and transesterification (biodiesel). Once refined, glycerin is used for a number of personal care items (such as toothpaste) or as a building block for other chemicals (such as propylene glycol).
The process of refining crude glycerin involves the removal of contaminants such as salts, unreacted fats, matter organic non-glycerin (MONG), water, and other impurities. Depending upon the feedstock characteristics, the crude may need petreatment and evaporation prior to refining. In many cases, such as that for biodiesel crude, the crude can be sent directly to the refining process.
In a typical refining system, glycerin is delivered to the crude still, evaporated, contacted with stripping steam throughout the column, and is recovered in the packed column section.
After being recovered from the crude still, the deodorizer further purifies the glycerine by removing unacceptable volatiles and also reduced the color. The purified product is cooled and passes through activated carbon beds, then through a polishing filter and cooler. Foots from the still are typically pumped to a foots still for additional glycerin recovery. Residue from the foots still, which typically include the salt, MONG, and other non-volatile materials, can be discharged as a feed additive containing 10 - 15% residual glycerin. For even higher glycerin recovery, a wiped film evaporator can be supplied instead of the foots still.
As motive steam for a vacuum system consumes much of the utilities associated with the glycerin recovery system, Crown as developed a number of unique energy saving systems. For evaporation, a triple effect evaporation system is the standard design. For the refinery, a variety of vacuum systems, including direct and indirect contact are available. For the ultimate in cost-effective steam savings, Crown's patented sub-zero vacuum system is a very attractive option.
Features of our Glycerin Refining System include:
Can also be used to provide higher glycerin concentration purity.