GENERAL INTRODUCTION
Geared to young and seasoned professionals alike, “
Beyond back-to-basics: Process principles and concepts” is
a new series of articles designed to present a straightforward approach to mastering the principles and concepts
all process engineers should be able to apply without the
need of a computer.
While simulations and models are useful for examining
long-term operational issues, they cannot replace the
dimension of human logic and reason required when
tackling the array of complex—and sometimes life-threat-ening—situations that occur in process plants.
Using experiences from the author’s more than 50-year
career in the process industry, articles in the series will
provide approaches to understanding core process concepts in ways that will equip the engineer to walk out of
an offce, into a plant, and directly resolve process def-ciencies via small operational changes or simple retrofts.
PROCESSING
TECHNOLOGY
Norman P. Lieberman
Process Improvement Engineering
Metairie, La.
Understanding draft
limitations in fired heaters
A South American refinery’s experience with a
draft-limited fired heater emphasizes the pivotal
role process engineers play in finding solutions to
problems that occur in plant equipment.
To be effective, the engineer must quickly call
upon elementary engineering principles, conduct
thorough field investigations, and communicate with equipment operators.
An example of this approach to solving operational issues
occurred at Ecopetrol SA’s 165,000-b/d refinery in Cartagena, Colombia, where a process engineer’s request for proofreading help initiated a lesson for anyone involved in running an industrial process plant.
The steps taken to resolve the heater’s draft deficiency
involved hands-on inspection of field equipment and operating conditions alongside basic calculations to determine
available draft in the heater’s stack.
The solution enabled the refinery to avert costs and delays
associated with an alternative proposal to contract
computer software simulations. More importantly,
the solution safeguarded lives that could have been
lost during the wait for simulation results.
Heater draft limit
“Que pasa, mi amigo, Pedro?”
“Señor Norm, por favor, could you look over
this letter to Foster Wheeler Corp. in New York to
make sure it is all correct, all in proper English?”
Given the cost and distant deadline of the proposed ar-
rangement, the author pressed for additional details, at
which point the young engineer revealed:
• The stack was very tall (about 50 m high).
• The stack damper was wide open.
• When refinery personnel opened the burners’ air registers, flue gas was blowing out of the furnace sight ports
because of positive pressure beneath the bottom row of convective tubes.
To make matters worse, the heater was burning fuel oil
with 3% sulfur content, which meant the flue gas blowing
from those sight ports contained toxic SO2.
Alarmed by the dangerous and potentially deadly situation created by the ongoing SO2 release, the author agreed
that ( 1) positive pressure indeed existed at the top of the
furnace’s radiant section, and ( 2) the next step required a
trip to the plant.
The office is a fine place to establish that a problem requires corrective action, but talking alone is unlikely to lead
to the proper one.
A red balloon
During the drive out to the Cartagena plant, the author reflected on how little he’d progressed from childhood in the
sense that the tests he runs in process plants today are near-
BEYOND BACK-TO-BASICS: PROCESS PRINCIPLES AND CONCEPTS— 1
