The document summarizes how a Hydroscav oil purifier was used to solve a problem at a Shell Oil facility where liquefied gas was leaking into and contaminating expensive synthetic lube oil. The Hydroscav purifies oil using a process called air stripping to remove contaminants like water and hydrocarbon gases. It was estimated to pay for itself within two months by allowing the facility to recycle contaminated oil rather than disposing of over 200 gallons per day.

1. A Hydroscav Reduces Waste Oil and
Produces a Fast Payback
WHITE PAPER
© 2017 AGC Refining & Filtration LLC

2. AGC REFINING & FILTRATION
A HYDROSCAV REDUCES WASTE OIL AND PRODUCES A FAST PAYBACK 2
Contents
The Problem 3
The Hydroscav Oil Purifier 3
Description of the Process 4
Payback Period 4

3. AGC REFINING & FILTRATION
A HYDROSCAV REDUCES WASTE OIL AND PRODUCES A FAST PAYBACK 3
The Shell Oil Company facility at Deerpark, Texas—located alongside the Houston Ship Channel—is a
fully integrated refinery and chemical plant that produces a full range of refined petroleum products and
petrochemicals.
The Problem
In early 1995, a new compressor for processing light hydrocarbons (C4 and C5, propane and butane)
was brought online for the liquefaction of these products. The lube oil system was charged with expensive
synthetic oil. From the first startup, it was found that the liquefied gas was leaking into the lube oil. The
gas was becoming entrained in the oil diluting it, lowering its flash point and viscosity, and reducing the
lubricating capability to unacceptable levels.
While the root cause of the problem was not immediately obvious, the problem was initially solved by
continually replacing the old oil with new oil. This proved to be too expensive for a long-term solution.
Two plant engineers were determined to find a solution besides wasting over 200 gallons per day of
synthetic oil, resulting in a monthly charge of approximately $30,000 USD (considering cost of new oil,
labor to change the oil, and disposal costs in 1995).
The Shell engineers reviewed the possible solutions, which were:
 repair the leaking compressor shaft seals or
 purify the oil and recycle it into the system.
The latter alternative was chosen because an unscheduled shutdown of the compressor would have been
prohibitively expensive at the time.
The problem was presented to a supplier—Powertherm Inc. of Houston—who, in turn, presented it to one
of their principal companies, AGC Refining & Filtration, LLC, The Springfield, Missouri-based engineering
and manufacturing organization had over 50 years’ experience in designing oil purifying equipment that
could restore the oil to like-new conditions. Allen Filters Inc.’s engineers reviewed the laboratory tests of
the contaminated oil submitted by Shell and recommended their model HS200 Hydroscav™ Oil Purifier.
The Hydroscav Oil Purifier
The Allen Hydroscav Oil Purifier is based on the principle of air stripping. This is the removal of
contaminants in the vapor phase after application of heat and intimate mixing with air or nitrogen in a
patented Aero-Jet Mixer™. Moisture and other contaminants are separated from the oil in a separator
vessel and discharged into the atmosphere or to a flare line. A Hydroscav removes free, emulsified, and
dissolved water down to 10 to 40 ppmw and—with a nitrogen package—all but a trace of dissolved
hydrocarbon gases (up to and including C9). A pre-filter can remove solids down to 0.5 micron if needed.
The Hydroscav is used for purification of small to medium quantities of contaminated oil.
The Hydroscav HS200-EPRX1 is an explosion-proof system designed to process 200 gallons of oil per
hour on a continuous basis. A nitrogen package can be added to remove the entrained and dissolved
hydrocarbon gases. Nitrogen is injected at a flow rate that can vary between 3 and 12 SCFM (depending
on the level of contamination) to remove the hydrocarbon gases. Complete removal of the hydrocarbon
gases may require several cycles through the unit, however most of the lighter and most volatile
components of the contamination are removed in the first pass.
Table 1: Hydrocarbons Removed After One Pass Through the Hydroscav
Hydrocarbon Percent Removed
Hydrogen 99

4. AGC REFINING & FILTRATION
A HYDROSCAV REDUCES WASTE OIL AND PRODUCES A FAST PAYBACK 4
Methane 97
Ethane 90
Propane 77
Pentane 35
Butane 60
Hexane 18
Heptane 9
Octane 4
Nonane 1.7
Description of the Process
A positive displacement gear-type inlet pump forces the oil through a filter vessel that contains a stacked-
disc, edge-loading 5-micron filter element (other micron sizes are available). From the filter, the oil flows
through a low-watt-density, flow-through, non-contact heater specifically designed to not cause localized
hot spots or carbonization of the oil. The heater raises the oil temperature to between 150–170 °F prior to
entry into the Aero-Jet Mixer where air or nitrogen is injected and intimately mixed with the oil. Hydroscav
units designed for only water removal or other non-volatile contaminants only admit air at this point.
In the separator vessel, the vapor phase containing moisture and hydrocarbon gases is separated from
the liquid phase (oil) and is vented through a top vent into the atmosphere or a flare line. Dehydrated,
purified oil is pumped form the bottom of the separator vessel and returned to the reservoir.
Payback Period
The installation, commissioning, and startup of the unit described in this white paper proceeded without a
problem and Shell engineers calculated the payback period to be approximately two months.

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