Collection A fleet of more than 60 trucks is operated by Evergreen in its collection business throughout California and adjoining states. Most drivers have well established collection routes thus providing confidence in the quality and consistency of the material routinely collected. Rerefining Used oil undergoes six processing steps in the plant, with hydrogenation as the vital stage in restoring the oil to a quality level equal to virgin material. Step 4 - the remaining hydrocarbon stream containing dirt, metals and polymeric material is then fed to a high vacuum, thin film evaporator which provides high temperature, low residence time flash conditions from which a residual bottom stream is produced that is used as a flux in the asphalt industry. Step 5 - here high temperature catalytic hydrogenation takes place in three reactor stages that remove sulphur, chlorine, and, most importantly, any remaining carcinogenic species from the lubeoil.
Yields are very stable, reflecting consistency in the feedstock collection system.
In its early days, the Evergreen plant delivered rather erratic performance principally due to the fouling that occurred in unexpected amounts in unexpected places. Unforeseen chemical reactions were occurring in addition to the desired physical separation processes. Thus the availability in California of hydrogenated, rerefined product was delayed whilst these teething troubles were resolved by the introduction of proprietary Mohawk pretreatment technology. Now, with dramatically improved plant performance and changed attitudes towards recycling, baseoil is sold at parity with virgin material. In addition, formulated lubricants bearing the Evergreen name have been on sale in California for a number of years, proudly indicating their environmental origin.