Chemical Engineering October 2020 - 30

Feature Report
Rapid Maintenance Response:
When Plants Can't Wait
Even with advanced predictive technologies, unplanned equipment failures can still
occur. In these instances, as shown in this boiler example, rapid maintenance action is
crucial to minimize downtime
Adam
Crosswell
Sulzer Chemtech
IN BRIEF
WHEN EQUIPMENT
REACHES A BOILING
POINT
THE POWER OF
AUTOMATION
GOING THE EXTRA MILE
M
aintenance activities generally
fall into two categories - reactive
and preventative. The first focuses
on repairing an asset once
a failure occurs, while the second aims to
avoid asset failure and repairs by preventing
issues before they happen. Such preventive
measures are achieved by using predictive
methods that leverage theoretical rate of failure
and actual equipment performance.
In an ideal world, rather than relying on
reactive maintenance, a chemical processing
plant will employ planned preventative
activities to minimize downtime. However, in
practice, unexpected equipment failures do
happen, resulting in unplanned shutdowns
and turnarounds. Businesses can still make
the most of the circumstances by promptly
adjusting their maintenance schedules to
bring forward equipment-optimization projects.
To succeed in this strategy, comprehensive,
responsive maintenance practices
are needed to support businesses.
High-quality predictive models enable
businesses to plan suitable maintenance
schedules that maximize equipment lifespans
while minimizing the environmental impact,
costs and downtime associated with
replacing damaged units or components.
Accurate and reliable simulations of equipment
or component failure are a key asset.
However, machines can sometimes still experience
unexpected issues.
In these situations, it is crucial for faciliFIGURE
2. Boiler inspection led to the recommendation to
clad, or weld overlay, the damaged areas
ties to be as flexible as possible, readjusting
their maintenance schedules and intervening
quickly to restore optimum operations with
minimal downtime. In addition, they can turn
the situation to their advantage, using the
shutdown to complete regular maintenance
activities that were scheduled to take place at
another time. In this way, plants can maximize
their annual uptime. To outline such responsive
strategies, a maintenance project involving
boilers at a real-life waste-to-energy plant
is used as an example in this article (Figure
1), but these maintenance principles are applicable
to any type of boiler that is exposed
to harsh conditions.
FIGURE 1. The unplanned failure of boiler equipment required
the rapid restoration of the boiler's structural integrity to help
restore its operations quickly
30
When equipment reaches a boiling point
The waste-to-energy plant referenced in this
article incinerates 750,000 metric tons of residual
municipal solid waste (MSW) per year,
which would otherwise be sent to landfill.
The heat generated by the process is used
by boilers to heat water and produce steam.
Boilers - critical equipment in wasteto-energy
plants, and many other types of
processing units - are regularly exposed to
harsh operating conditions. For example, in
boilers, waste with large volumes of plastics,
or materials containing paint or glue, will generate
a broad range of volatile compounds
containing chlorine, sulfur, alkali and heavy
metals, as well as hydrochloric acid and
chloride salts. The presence of various impurities
in the combustion gases can cause eroCHEMICAL
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Chemical Engineering October 2020

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