The value of listening to your
One important test of central plant operations is the planned shutdown of the
entire plant. Recommended during commissioning, this test enables plant owners
to identify and correct any operational issues so that they may be avoided in the
event of an electrical power outage. However, under pressure from consumers to
not interrupt their utilities, owners typically do not want to perform this test –
preferring to wait until systems are tested ‘in real time,’ during an actual loss of
power. Plant owners may regret such a decision after that fact.
In 2003 RMF Engineering was hired by a university to perform independent
third-party commissioning services for a new central energy plant during its construction. This consisted mostly of verifying installation checklists and conducting
the functional performance testing of the chilled-water, condenser water and electrical systems. The firm tested each of these systems to ensure that they operated
as designed and were integrated appropriately. However, the firm was not permit-ted to simulate an electrical outage to observe how the plant would respond and
how the systems would come back on line after a major service disruption. The
plant operator was adamant that he could not tolerate a plant shutdown: His consumers would be furious; moreover, the plant was partially on emergency power.
One hot August weekend, a storm came through and interrupted the main
electrical power service, shutting down the chillers. One chiller, on emergency
power, came back on line after the 10 or so seconds it took the generator to
re-establish power. Everything worked as designed. After a while, the utility company fixed the problem, and it was time to switch the plant back to normal power.
Before the switch back to normal power, however, the controls system had been
calling for more chillers to start due to the load the campus imposed on the system.
They couldn’t start because no power was available. When normal power was
introduced back to the plant, the entire plant immediately went black.
What had happened? Since the plant shutdown had not been performed, the
coordination of the electrical breakers wasn’t tested. Once power was again available to all of the equipment that was trying to operate – but previously could not
without power – all of the equipment tried to start at once and created such an
electrical demand that the breaker at the utility’s substation tripped, and all power
to the plant was lost. The electrical equipment in the plant serving the chillers was
supposed to trip first and keep the other plant systems operating. However, the
time settings on the breakers were adjusted incorrectly, so the utility’s equipment
tripped first – resulting in a huge inconvenience that commissioning could have
avoided with testing.
boilers were not capable of reaching
capacity at the efficiency specified.
Realizing this, the owner simply
refused to accept the boilers. Ultimately
the boiler manufacturer came in, removed
the boiler refractory and added additional tubes to each boiler to get them
to meet specifications and for the owner
to accept them.
In another boiler plant, testing during
commissioning revealed that the emissions
from the burner at the low and mid firing
range were higher than had been specified.
Later this issue proved not to be that large;
however, it did affect the plant’s Title V
operating permit, which kept them in
compliance with the U.S. Environmental
Protection Agency and their state’s Title
V, Part 70, permitting agencies.
Without commissioning, the plant
owners in both these examples likely
would have never realized that they had
not received what they had paid for –
and probably would have blown their
operations budgets to boot.
adjusted to match the corresponding
full-load amps associated with the motor
it is driving. What could be worse for an
operator than to learn that the motor
just burned up due to an avoidable
installation error! Commissioning can
identify these types of issues while the
contractor still owns the equipment –
and before the operators are forced to
discover them at the very time they most
need the backup functions.
Three issues that an operator would
probably never identify without commissioning are undercapacity, inefficiency
and emissions problems. For example, a
plant owner was constructing a new boiler
facility containing three 80,000-lb/hr
water-tube boilers specified, as is typical,
with a minimum thermal efficiency (input/
output). By testing the functional performance of these boilers, the commissioning team quickly discovered that the
Testing Interacting Systems
The commissioning process also tests
one system’s interaction with another. In
a central energy plant, there are numerous
supporting systems – e.g., the fuel oil
system, condensate systems and metering – which must be set up correctly for
the main system to operate at optimum
efficiency. Testing these various supporting
systems through commissioning helps
plant owners, operators and designers
settle any debates as to where problems
may be coming from or what any one
system is supposed to do and how it is
intended to interact with the others.
Furthermore, the meters can be verified
during this time to help ensure that what
is being billed by the utility is based on
actual consumption. This testing also
helps establish an energy baseline that
can be referred to in the future. System
owners and operators often say that their
system could never perform as intended.
Commissioning the system will either
prove or disprove this statement.
Who Can Benefit?
In general, all central energy plants
can benefit from commissioning. That
includes existing facilities as much as, if
not more than, new plants. There is, in