Magnetic Micro-Particle Separator
EXPORTech has developed a continuously operating primary filtration technology (US patents pending) for separation of nanometer sized magnetic particles from process flows. The technology was demonstrated and applied to removal of iron-based catalysts from Fischer-Tropsch wax. A Fischer-Tropsch catalyst/wax slurry with 15 to 25 wt.% catalyst was processed to produce wax with nominally 0.1-0.5 wt% catalyst at 500oF at the rate of 50 barrels per day with a continuous filtration rate of 20,000 liters per hour per square meter.
The operating mechanism of the separator is housed between the poles of an electromagnet producing a magnetic fields 0.2 Tesla throughout the working volume. The method achieves high levels of catalyst separation from the wax by promoting magnetic agglomeration throughout the volume of the vertically oriented elongate cylindrical separation vessel. Downwardly-directed high velocity jet flows located adjacent to the inside walls of the separation vessel nearest the magnet poles are used to sweep the catalyst agglomerates from the magnetized volume of the separator. The jets are controlled to promote movement of the agglomerates without causing turbulent mixing. Clean wax with a low concentration of catalyst is continuously issued from the top of the separator while wax slurry with a high concentration of catalyst is issued from the bottom of the vessel. Use of a supplemental separation method such as batch operated high gradient magnetic separation to treat the product of the first stage continuous magnetic separator has produced clean wax containing 0.01 wt.% catalyst.
This enabling technology will have application in Fischer-Tropsch synthesis of coal, petroleum coke and other disadvantaged carbon sources such as coal refuse. Additionally, the method can be used in high temperature and high pressure separation of magnetic materials in petrochemical and biochemical applications, including separation of particles of wear from cobalt catalysts. It has a significantly higher flow than dynamic settlers or mechanical filters, is continuous, and is non-pluggable.