Page 370 - Sustainable On-Site CHP Systems Design, Construction, and Operations

Fort Bragg CHP 343

Key Outcomes Remarks
1. Site operating staff should maintain Poor planning can result in lost operating
a proper inventory of critical spare time of the CHP system from unplanned
parts or plan carefully to be sure they outages caused by a lack of the necessary
are procured before they are needed. spare parts
Examples are air and fuel filters, and
other key consumables
2. High fuel prices (vs. electric prices), This illustrates the benefit of having control
during periods of low thermal loads can optimization capability
make it uneconomical to operate the
CHP system
3. If not carefully planned, emissions Begin the permitting process early,
permitting can delay initial plant start-up and follow up to make certain that all
and commissioning requirements are met prior to completion
of the site construction work
4. Interconnection with local electric Coordination with the electric utility on
utility (protective relaying, etc.) is a key commissioning the interconnection is one
element of a CHP project of the key elements of plant start-up

TABLE 20-6 Key Operations-Related Outcomes of the Project

The operating history of the CHP system was carefully monitored during the initial
months of operation. A list of key outcomes relating to CHP plant operations is shown
in Table 20-6.

Future Directions
Over the first 4 years of operation, plant operators at Ft. Bragg found that the system
provided good performance, but required more maintenance than they had expected.
In addition, some of the CHP equipment is unlike other equipment in the army’s
central heating and cooling plants, thereby requiring the use of outside contractors
for some specialized maintenance work. During the first 4 years of operation of the
CHP system, there was a large increase in the connected cooling load due to new
building construction on the post. This increased cooling load will require modifica-
tions to the 82nd Central Heating Plant. These modifications are planned to include
revisions to the chilled water distribution system to enable better use of the existing
electric-driven chiller and the addition of new chiller capacity. Experience has shown
that during periods of high cooling demand, the connected buildings on the post
require a chilled water supply delivered at 42°F, which has been difficult to achieve
with absorption technology. As a result, the army is exploring options to deactivate
the exhaust-driven double effect absorption chiller as part of the planned plant
modifications.
This new direction is not a reflection of the suitability of exhaust-driven absorption
technology for CHP systems. Exhaust-driven absorption chillers or chiller-heaters
remain a viable design option that should be strongly considered in planning any CHP
system application.