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Tampa Electric Installation
Basalt Lined Abrasion Resistant Pipes from
Abresist Save Utility Ten Years of Annual Maintenance and
Costs
Author information - This article was prepared
through joint efforts between Abresist Corp., Urbana, IN and
Tampa Electric Company, Tampa, FL.
 Moving
bottom and fly ash can create massive maintenance and budget
problems for coal burning utility plants. The abrasive ash
quickly erodes most pipeline. Replacing blown pipe eats into
the budget and means downtime.
Tampa Electric Company (TEC), Tampa, Florida,
is no stranger to ash line maintenance. Its Big Bend Station,
located 15 miles south of Tampa in Apollo Beach and its Gannon
Station, located just 10 miles north of Big Bend on Tampa
Bay, are both coal-fired power plants. Thousands of feet of
pipe snake through the plants, conveying the abrasive bottom
and fly ash created by the burning of the coal. Big Bend Station
with a 1755 MW capacity is TEC's newest and largest power
plant. It provides more than half of the company's total generating
capability. The Station burns approximately 14,000 tons of
bituminous Kentucky coal every day.
Big Bend Units One, Two and Three with a combined
capacity of 1285 MW, burn low sulfur coal. Big Bend Four with
a 470 MW capacity burns standard sulfur coal and is equipped
with a flue gas desulfurization system (FGD) or "scrubber"
to remove the sulfur, one of the first to be designed and
installed in the United States to produce commercial grade
gypsum as a by-product.
The abrasive ash depicted
here can create massive pipe problems for coal burning
utilities. ABRESIST® basalt lined pipe has handled
the abrasive ash for ten years at Tampa Electric and is
still in excellent condition. |
Built between 1957 and 1967, Gannon Station
has six service units and a capacity of 1230 MW. It burns
low sulfur coal. At both plants, the company had experienced
problems with hardened steel and cast iron slag sluice lines.
The hardened steel lines lasted an average of eight to 18
months; the cast iron sections often had to be changed or
rotated every four to six months.
In the late 1970s, plans to build Big Bend Four
and conversion plans at Gannon Station provided TEC with an
opportunity to solve its persistent pipeline abrasion problems.
TEC engineering set up an on-site test to determine what type
of pipe could withstand the abrasive ash. Several pipe manufacturers
were invited to submit samples for testing.
Eight manufacturers of PVC pipe, unlined fiberglass
pipe, fiberglass pipe lined with ceramic tile, carbon steel,
cast iron, basalt lined pipe and ceramic component pipe submitted
samples. To ensure fairness, the test pipe was installed in
similar locations and in areas where wear was usually most
severe.
Some of the test pipe failed in minutes, some
in hours. Others lasted months and longer. A basalt-lined
pipe manufactured by Abresist Corporation, Urbana, Indiana,
was among the pipes that lasted the longest and was still
in service where it was tested until it was replaced in 1990.
Commenting on the results, Rex Morgado, Tampa Electric Engineering
Technician, said, "The amount of wear was significant
in all the others, but not ABRESIST®."
 TEC
officials reviewed the results and talked with another utility
that used the basalt lined pipe. After factoring in cost evaluations
and a ten-year warranty from Abresist, they chose to install
the basalt lined pipe.
The ten-year warranty was twice the normal usually
given. Abresist asked only that they be allowed to inspect
the pipe at five and ten year intervals.
Two, mile long, ten-inch basalt pipelines were
installed at Big Bend. One pipeline conveys bottom ash; the
other line conveys fly ash. Jetpulsion™ power drives
the ash and water through the pipe at a velocity of eight
to 12' per second. Big Bend is a closed loop system so the
water from the slurry is run through weirs to retention ponds
for reuse.
At the same time TEC was building Big Bend Four,
they were converting some of the units at Gannon Station to
coal-fired units. Initially, all six units burned coal. During
the 1970s, four of the units had been converted to oil-fired
to meet environmental requirements. The other two units had
continued to burn low-sulfur coal.
Rex Morgado, Tampa Electric
Engineering Technician, measures the wear on an ABRESIST®
basalt lined straight pipe at Big Bend. |
In the early 1980s as oil prices began to rise,
TEC reconverted the oil burning units to coal burning units
that used low-sulfur coal.
During the conversion, TEC installed approximately
1200' of 8" ABRESIST basalt lined pipe to convey bottom
ash slurry from Gannon One, Two, Three and Four to dewatering
bins. Over ten million gallons of saltwater and bottom ash
slurry are moved through the pipe at 110 psi by high pressure
saltwater pumps.
Over the long haul, how did the basalt lined
pipe withstand the abrasion?
In 1989, at the five-year warranty inspection
at Big Bend and Gannon, the straight pipe showed little to
no wear. At elbows and turns, where the flow direction changes
and wear is usually most severe, there was only an 3.18mm
(1/8") of wear or less. ABRESIST elbow lining is 30mm
(1.18") thick while standard straight pipe is 22.3mm
(7/8"). In some places, the swirl pattern from the original
manufacturing process was still evident.
At the ten-year inspection in July 1994 at Big
Bend Four, the basalt pipe once again showed little wear,
even in the elbows. Some of the original glazing was even
still visible.
During the ten-year inspection at Gannon Units
One, Two and Four showed some wear, about 4mm (.158")
was observed near the pipe ends. The rest of the pipe showed
little wear.
At Gannon Unit Three, one 90 degree elbow exhibited
more wear, about 8-10mm (.316" to .394"). This same
elbow was inspected at the five-year mark.
Morgado was on hand at both the five- and ten-year
warranty inspection. He said, "Even though the wear was
atypical, there was not much difference between the five-
and ten-year inspections with this elbow."
Due to the excellent performance of the basalt
lined pipe, TEC subsequently installed ABRESIST pipe in Gannon
Five and Six and Big Bend One, Two and Three. Morgado said,
"Based on previous experience with the basalt pipe, we
installed ABRESIST to convey all of the bottom ash at Gannon."
In business for almost a century, Tampa Electric
is an investor owned utility. The company serves 480,000 customers
in a retail service territory covering nearly 2,000 square
miles in west central Florida. Its parent company, TECO Energy,
owns several energy related companies which are involved in
mining, transportation, wholesale power and other diversified
interests.
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