Lean Oil Absorption Vapor
Recovery Equipment
PROCESS DESCRIPTION
Lean Oil Absorption systems, along with Refrigeration Condensation, were
among the earliest vapor control technologies to be utilized in the terminal
industry for the control of vapors generated by product transfer operations. The
theory of operation of lean oil absorption is relatively
uncomplicated. The lean oil is forced to make intimate contact with
the hydrocarbon contaminated air stream. This is usually accomplished in a
column where the vapor rises through the column counter flow to the liquid
coming down the column. As part of the column, a packing material, trays or
spray nozzles are used to "break-up" the liquid so that the contact
between the liquid lean oil and the vapor is enhanced.
The liquid absorbent or lean oil is so named because it is initially deplete
(lean) of the compounds found in the vapor stream. As the lean oil and the vapor
are brought into contact, the hydrocarbon compounds in the vapor are absorbed
into the liquid and the liquid absorbent is now comprised partly of the
hydrocarbons found in the vapor stream. If this liquid is re-circulated for a
long enough period, the hydrocarbons found in the vapor begin to make-up a
sizable portion of its composition. In time the liquid and vapor reach
equilibrium and the liquid is no longer able to absorb any more vapor
hydrocarbons, the liquid is said to be saturated or "rich." If the
liquid absorbent is to be reused in the absorption column it must be regenerated
before it becomes saturated. Regeneration is usually accomplished thermally and
the vapor hydrocarbons are flashed out of the liquid and recovered. The liquid
can then be re-used as an absorbent. In certain applications, the absorbent can
be circulated on a "once through" basis and then returned to storage
for further use in a different application, such as feed stock to various
refinery processes.
For Lean Absorption technology to function within the required emission
limits for any vapor phase hydrocarbon pollutant, the absorbent must be
correctly chosen, the severity of the regeneration and its frequency must also
be correctly determined.
Manufacturers of Lean Oil Absorption Units are:
