Technical Manual - Section 3 (Safety Hazards)

LUBRICANT, WAX, AND GREASE
MANUFACTURING PROCESSES
Lubricating oils and waxes are refined from the residual
fractions of atmospheric and vacuum distillation. The primary
objective of the various lubricating oil refinery processes is to
remove asphalts, sulfonated aromatics, and paraffinic and
isoparaffinic waxes from residual fractions. Reduced crude
from the vacuum unit is deasphalted and combined with
straight-run lubricating oil feedstock, preheated, and
solvent-extracted (usually with phenol or furfural) to produce
raffinate.
WAX MANUFACTURING PROCESS
Raffinate from the extraction unit contains a considerable
amount of wax that must be removed by solvent extraction
and crystallization. The raffinate is mixed with a solvent
(propane) and precooled in heat exchangers. The
crystallization temperature is attained by the evaporation of
propane in the chiller and filter feed tanks. The wax is
continuously removed by filters and cold solvent-washed to
recover retained oil. The solvent is recovered from the oil by
flashing and steam stripping. The wax is then heated with hot
solvent, chilled, filtered, and given a final wash to remove all
oil.
LUBRICATING OIL PROCESS
The dewaxed raffinate is blended with other distillate
fractions and further treated for viscosity index, color,
stability, carbon residue, sulfur, additive response, and
oxidation stability in extremely selective extraction processes
using solvents (furfural,
phenol, etc.). In a typical phenol unit, the raffinate is mixed
with phenol in the treating section at temperatures below 400º
F. Phenol is then separated from the treated oil and recycled.
The treated lube-oil base stocks are then mixed and/or
compounded with additives to meet the required physical and
chemical characteristics of motor oils, industrial lubricants,
and metal working oils.
GREASE COMPOUNDING
Grease is made by blending metallic soaps (salts of
long-chained fatty acids) and additives into a lubricating oil
medium at temperatures of 400-600º F. Grease may be either
batch-produced or continuously compounded. The
characteristics of the grease depend to a great extent on the
metallic element (calcium, sodium, aluminum, lithium, etc.)
in the soap and the additives used.
SAFETY AND HEALTH CONSIDERATIONS
Fire Protection and Prevention
The potential for fire exists if a product or vapor leak or
release in the lube blending and wax processing areas reaches
a source of ignition. Storage of finished products, both bulk
and packaged, should be in accordance with recognized
practices.
While the potential for fire is reduced in lube oil blending,
care must be taken when making metal-working oils and
compounding greases due to the use of higher blending and
compounding temperatures and lower flash point products.
Table III:2-22 LUBRICATING OIL AND WAX MANUFACTURING PROCESSES
Feedstock From Process Typical products................To
Lube Vacuum tower, solvent Treatment Dewaxed raffinate............. Lube blend or
compound
feedstock dewaxing, hydrotreating Grease compounding
and solvent extraction, etc. Wax............................... Storage or shipping
additives
III:2-48