Page 15 - Industrial Plant 2020

Fired heater revamp to reduce

emissions

Reducing the CO emission in the flue gas by means of a new
catalytic system to be installed in an existing fired heater, while
maintaining the CO production unchanged

Mauro Bertolini, Daniele Brambilla,
FW Fired Heaters, Technology and Products, Wood

ood’s FW Fired Heaters (UHC). Based on the composition of the refinery fuel
division in Milan – which sits gas and fuel oil normally used, other compounds
within the Technology and emission is rarely expected and most of the times not
Products business group - monitored.
supported a client with the All pollutants contribute to environmental issues:
W reduction of CO emissions greenhouse effect and global warming, formation of
from an existing fired heater. smog and acid rains. These pollutants can also lead to
The scope consisted of assessing the existing system corrosion and integrity issues within the equipment and
and proposing the best revamp solution to minimize the unit.
CO formation. Due to the turnaround duration and plot
plan constraints, the removal of the root cause was SOx content in the flue gas is stoichiometric to the
deemed to be too challenging. The client asked Wood sulphur compounds in the fuel sent to the burners. To
to look at an alternative approach which involved a reduce the SOx content in the flue gases it’s possible to
reduction of the CO emission in the flue gas by using a decrease the sulphur in the fuel by means of sulphur
catalytic system, keeping the CO production removal systems or fuel blending upstream; as an
unchanged. Wood’s Fired Heaters team designed the alternative, by installing a de-SOx system in the
bespoke catalytic system solution for the client, and downstream equipment.
following the successful completion of this work, Wood The same dependence on fuel quality can be found
was awarded a contract for the engineering and also for fuel-bound NOx and particulates which are
material supply of the catalytic system package to be normally not an issue when the fired heater is firing only
installed in the existing fired heater. fuel gas, while are taken into consideration when fuel oil
is fired.
Therefore, a fired heaters’ most critical pollutants are
Fired Heater Emissions NOx and CO emissions and the clients require

In a refinery or plant, a fired heater is one of the main guaranteed values for those two parameters.
pieces of equipment that releases contaminated
emissions into the atmosphere. To minimize NOx contents in the flue gas, many
Being the result of a combustion reaction, CO improvements have been made in the last decades.
2
emissions released into the atmosphere cannot be These include:
avoided, and can only be reduced by increasing the • Systems to reduce the NOx formation: design and
efficiency of the fired heater. production of low NOx and ultra-Low NOx burners
For what concerns the other emissions they include based on many different concepts such as fuel/air
NOx, CO, SOx, particulates, and unburnt hydrocarbons staging, flue gas recirculation, cool flame and

IndustrIal Plants - May 2020
13