POWER June 2020 - 17

FOCUS ON O&M
■ A new three-cell cooling tower was
erected to handle the condenser water
off the new chillers.
■ New office space, locker facilities, and
control rooms were added.
Demolition was carefully planned as
3. Construction crews lift one of the facility's
boiler units. The team removed four coal-fired
boilers and replaced them with two gas-fired
boilers during the construction phase. Courtesy:
The Boldt Company
as we were isolating operating elements
and planning renovations. "
Construction crews operated in a collaborative
environment using Boldt's Integrated
Lean Project Delivery (ILPD).
This process combines up front collaboration
between all parties with the
waste-reducing lean principles and is
designed for uninterrupted workflow and
an increase in value-add activities. Crews
relied on rigorous standard process, visual
controls, and collaborative communication
of the production plan on a daily
and weekly basis.
Demolition and renovation called for:
■ Three steam-driven turbines were removed
and the turbine hall was renovated.
■
Four boilers were removed and replaced
with two new boilers (Figure 3).
■ Three new chillers (Figure 4) and three
chilled-water pumps were added, and
six turbine-driven prime movers were
converted to electric motors and variable
frequency drives (VFDs).
Boldt crews took apart the giant boilers
and supporting structures brick by brick.
The three coal boilers were five stories
tall with three-inch-thick steel drums,
each four feet in diameter. Crews used
torches to cut the boilers apart and
scrapped the steel to steadily deconstruct
the decades-old structure.
For construction crews, the challenge
was always providing N+1 redundancy
during all phases of construction to provide
adequate steam or chilled water to
fully functioning hospitals and clinics. " It
was like a dance, we had to continually
match capacity and provide backup before
we took any one process offline, "
Ehrfurth said. " We had to ensure that
temperatures in operating rooms were
sufficiently cool during surgeries, or provide
adequate heat to hospital rooms
during winter. " To further manage operations,
construction crews did boiler renovations
in summer months and chiller
renovations in winter.
You Can't Get There from Here
One challenge in construction was
the plant was physically located 800
feet from the campus-across one of
the busiest highways in the state of
Wisconsin. Expanding the distribution
system (see sidebar) for additional capacity
and better performance called for
adding 5,100 feet of chilled water piping
and 3,100 feet of steam piping. But
A Cleaner and More
Flexible Facility
The Milwaukee Regional Medical
Center (MRMC) has said the elimination
of coal and conversion of its
plant to natural gas reduced greenhouse
gas emissions by about 50%.
Redundancy at the site was created
through construction of a second
plant, which provides a continuous
supply of critical service, with two independent
thermal sources and onsite
alternate fuel backup. Reliability
was improved through investment in
plant and distribution infrastructure
to enhance an uninterrupted, consistent
source of thermal service.
The members of MRMC Thermal
are:
■ Froedtert Memorial Lutheran Hospital
■
Children's Hospital of Wisconsin
■ The Medical College of Wisconsin
■ Blood Center of Wisconsin
■ Milwaukee County Behavioral
Health
Some pertinent statistics about the
project include:
■ 7,500,000 square feet of conditioned
space
■ 22 buildings representing five customers
■
4 miles of steam and condensate
lines
■ 4 miles of chilled-water piping
■ 2,500 feet of steam tunnels
■ Peak chilled-water demand: 17,100
tons
■ Peak steam demand: 217,000 lbm/
hour
■ Largest chilled water line: 42-inch
HDPE and 36-inch PCCP
■ Largest steam line: 24 inch (15 psi)
and 12 inch (135 psi)
crews could not dig up the congested
highway used by as many as 30,000
vehicles (including emergency vehicles)
each day. Interrupting traffic was not in
the construction plan.
" The highway was new and there was
4. Construction crews lift one of the facility's chiller units. Three new chillers and three chilledwater
pumps were added to the facility. Courtesy: The Boldt Company
June 2020 |POWER
www.powermag.com
a six-year moratorium on excavating, "
Ehrfurth said. " We couldn't open cut,
so we opted for horizontal boring to run
the pipes under the highway. Conventional
wisdom indicates open cutting is
the most economical, but when you add
17

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POWER June 2020

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