Figure 3. Control Overview Screen, Illinois Street Chilled Water Plant.
Source: Citizens Thermal Operations.
differential pressure control and is staffed
with on-site operators 24 hours a day,
seven days a week.
A West Street Plant expansion was
completed in 2008, adding another 4,000
tons of capacity to the system serving
downtown Indianapolis. Plus, Citizens
has the ability to extend system capacity
by another 4,400 tons by operating two
customer plants. These plants are isolated
from the central system when activated,
freeing up plant capacity to serve other
cooling loads. (Citizens owns and operates an additional 20,000-ton plant that
serves one customer and is not connected
to the downtown chilled-water system.)
Two satellite chiller plants are
located approximately 2 miles to the
northwest and northeast, respectively, of
the West Street facility (fig. 2). The fol-
lowing additional chilled-water capacity is
installed at these plants and available for
dispatch:
l;
5,500 tons at the North Plant on the
The IUPUI campus’s North Plant is
located on the northwest side of Citizens’
distribution system. This is where
Citizens first began using the pump flow
control method in 2005. A total of 5,500
tons of chiller capacity was installed,
and the plant used a primary-secondary
pumping system. A controls update
in 2005 incorporated the flow control
method to manage the secondary pump
speed. The IUPUI chilled-water plant was
located in a modified steam plant that
was recently demolished. The old plant’s
chiller capacity was replaced with updat-
ed equipment and moved in 2007 to its
current site near the old steam plant.
The new chilled-water pumping system
selected was primary-variable-speed-drive
secondary, and a flow meter was installed
on the plant supply line for use as a sens-
ing input for pump speed control.
Timothy M. Anderson, PE,
LEED AP, principal at Applied
Engineering Services Inc., has
been a design consultant for 16
years. His engineering background
includes district chilled water and
steam generation, refrigeration and HVAC. A
registered professional engineer in Indiana and
Ohio, he previously served as the director of
engineering at the Cleveland district energy
system. Anderson graduated from Purdue
University with a bachelor’s degree in mechani-
cal engineering. Anderson may be reached at
tanderson@applied-e-s.com.
