Page 296 - Sustainable On-Site CHP Systems Design, Construction, and Operations

Operation and Maintenance Services 269

is ammonia injection systems for NO reduction. When CHP plants are near public
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areas, urea is often delivered and stored in lieu of ammonia itself. The urea is pumped
from the storage area and heated to be converted to ammonia just before it is injected
before the SCR unit. The delivery pipe, pump, and heater must be kept clean and must
be flushed with distilled water to prevent a urea build up that would eventually plug
the injection pipe and cause NO emissions to exceed limits.
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A second example is natural gas compressors. Many CTGs operate on natural gas
or other combustible gasses that require higher pressures than are available at the gas
main. The gas compressor boosts the gas pressure to the point that it will enter the
CTG. The gas compressor system incorporates filters that also require regular inspec-
tion and cleaning.
Another specialized system is the emissions monitor system, where stack gas is
sampled and analyzed on a continuous basis (CEMS). The CEMS must be calibrated
periodically as stated in the “permit to operate.” Any service required beyond standard
calibration should be performed by factory-trained technicians.

Down Time Planning
Down time planning to accomplish maintenance requirements can be a difficult task,
especially for facilities that demand 24/7 operation. Plant management must identify
times throughout the year, where the impact will be minimal to the mission of the orga-
nization to which the CHP supports. The biggest impact will be the increased costs of
electricity. In many cases the local utility will impose a costly standby charge whenever
the in-house generation goes off line.
Whenever the CTG is scheduled to be down for maintenance, all related equip-
ment will be down and should also be scheduled for maintenance. This maintenance
outage must be carefully planned to ensure that outside contractors are appropriately
scheduled well in advance and that all spare parts that would possibly be required are
on site. Factory maintenance contracts help to simplify the process with parts, labor,
and expertise.

CHP and the Plant Operator
A CHP design can provide projections of efficiencies that impress all of the stakeholders,
producing the funding and focus to build the facility or expand an existing facility. After
the plant is constructed and commissioned, plant operations must take over and demon-
strate that the design meets or exceeds the performance projections. This chapter has
outlined the importance of the exceptional operator as an individual and as a member of
the operations team and should be recognized as a key factor in the overall success of
any sustainable CHP operation.