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The building is a 5710 s.f.
structure of steel and masonry
construction. The majority of
the building is the 47' X 80'
engine room with a ceiling height
of 20', which houses the generators.
The rest of the building serves
to support the generator operations
and include the state of the
art control room, the switchgear
room and a conference room.
The exterior finish is a custom
order 12" fluted block.
There were approximately 6700
block used and each block weighs
60 pounds. Site work included
replacement of 500 feet of the
gas pipeline to serve the gas
supply to the correctional facility,
a new parking lot, landscaping
and a bio-retention pond.
Each of the four generators
has a 1500HP, twelve-cylinder
engine with 7040 cu. in. displacement.
They produce 1,000,000 watts
of power at 4,160 volts. They
consume approximately 350 cubic
feet of the landfill gas per
minute. They are 15 feet long,
7 feet wide and nine feet high
and weigh 37,500 pounds. The
generator units are placed on
individual inertia packs.
The generators are connected
to a 5kv switchgear lineup.
This 7-section switchgear parallels
the generators together. It
also distributes power to the
building via a 2000KVA 4160
to 480V transformer. Power is
exported to PEPCO via a 7500KVA
4160 to 13,750 volt transformer
and a 15KV switchgear outdoor
lineup installed in a new stand
alone structure.
In addition to the construction
of the new generator building
and installation of the new
generators, the project consisted
of completely gutting and renovating
the existing compressor building,
which processes the gas into
burnable fuel for the generators.
As part of this renovation four
gas-powered compressors were
removed and replaced by three
electrically driven compressors.
A new process chiller and filtering
system were also installed in
the compressor building upgrade.
The capacity of gas that can
be processed was increased by
225% by the upgrades. As well
as providing gas to the new
generators, the compressor building
supplies gas to three existing
generators and boilers at a
correctional facility two miles
from the landfill. The existing
system serving the correctional
facility has been in operation
since 1986.
The gas is extracted from the
hill by an extensive array of
wells connected to a common
pipeline header. In the first
step in the process the gas
header enters a knockout tank.
As it enters some of the moisture
and contaminants are dropped
out. The gas then passes through
a series of entrainment separators
to the compressors. The compressors
compress the gas to 80 PSI.
In this process the gas is heated
to approximately 100 degrees
F. The compressed and heated
gas is then cooled to 40 degrees.
The cooling process causes the
major amount of moisture to
condense. The cooled gas passes
through a battery of gas scrubbers,
filters, and dryers. These remove
the condensation along with
most of the others contaminants.
The clean and dry gas is then
ready to be utilized as fuel
for the generators and boilers.
All of the piping and processing
equipment are made of stainless
steel to be able to withstand
the corrosive properties of
the gas passing through it.
The complete plant operation,
power generation and gas processing
is fully automated by a PLC
based control system and data
acquisition system. Compressors
will automatically come up or
shutdown to maintain desired
capacity dependent on the demand
of the generators and boilers.
The generator will load and
unload to maintain a steady
level of exported power, selected
by the user, or to maintain
a specified number of generators
to maintain online status. The
plant is designed to run continuously
24/7. To ensure safety of the
operation, plant control is
interlocked to the fire alarm
system, a methane gas detection
system and oxygen level in the
gas. The presence of any of
these conditions will automatically
shutdown the plant. The automation
system also monitors gas pressures
above acceptable tolerances,
temperatures, flow rates and
moisture throughout the processing.
The generators are monitored
for engine oil temperature and
pressure, jacket water temperature,
cylinder and exhaust temperatures,
as well power output; KW, KWH
voltage and frequency. The power
usage and product at the remote
location of the correctional
facility are also monitored.
The operational status of the
primary building functions of
the flare building, another
remote location, are monitored
by the new DAS system. The building
ventilation is also controlled
automatically for temperature
as well as combustion air for
the generators.
To make this automation system
functional, 34,000 feet of control
cable were run using a distribution
system that included cable tray
and conduit. 2200 control point
terminations were made. All
of this in an area of less than
8500 square feet.
The project was challenging
in many regards including integrating
software and hardware systems
that have not been utilized
together previously. The intent
of the project was clear, however
the successful completion required
extensive modification and fine
tuning throughout the construction
process to achieve the end result.
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