POWER February 2014 - 34

InstrumentatIon & Control
systemwide integration. The key components
of a remote monitoring and diagnostics system
include:
■ The plant data acquisition systems and
plant data historians.
■ A reliable communications network between
the plant and a central data hub.
■ Analysis software at the data hub,
which employs advanced pattern recognition
to enable early detection and
diagnosis of plant equipment and performance
anomalies.
■ Operational intelligence experts, who
assess the data trends, alarms, and diagnostic
reports to determine if corrective
actions are needed to respond to a dynamic
situation.
Because many utilities have cut costs
dramatically by reducing their engineering
staff, some have turned to third-party experts
to provide their M&D resources. This
mode of operations provides many benefits
for the utility. Perhaps the greatest is avoiding
a large investment in engineering staff for
power plants that may potentially be idled
or even shut down due to economic or emissions
concerns.
Remote M&D Successes
For more than 20 years Black & Veatch
has worked with scores of utilities worldwide
to provide M&D services, and as a
result it has a wealth of success stories
from these efforts. Though some of these
successes may seem like " small potatoes, "
the benefits provided in terms of reduced
operating costs, improved heat rate, fewer
unplanned outages, and lower operations
risk typically far outweigh any investment
in an M&D system.
Case 1: A Mill Bites Off More Than
It Can Chew. Operators of one pulverized
coal unit believed that their coal mills
were performing within specifications, but
they were surprised when remote M&D engineers
noted a small but statistically significant
sudden increase to one pulverizer's
motor amps, differential pressure readings,
and hot air damper positions. Further analysis
revealed that the heat rate of the unit
would experience sudden variations whenever
that coal mill was brought into service
(Figure 2).
An analysis of the trends suggested that
the coal feeders were delivering more coal
to the mills than indicated, and fast-track
troubleshooting by the plant staff avoided
potential problems with both mill reliability
and combustion issues. They first
checked the gravimetric feeder's load cell
by calibrating the feeder, and then further
34
troubleshooting revealed a problem with the
feeder's variable-frequency drive, such that
the feeder was running nearly twice as fast
as indicated.
Because of the early warning from the
M&D system and engineers, the mill's perwww.powermag.com
formance
was quickly returned to normal.
Case 2: Turbine Troubles Tackled. John
Twitty Energy Center (JTEC) Unit 1 is a
194-MW coal-fired unit. Due to a shortage
of on-site engineering staff, JTEC chose to
use remote monitoring to leverage off-site
POWER | February 2014
3. One of our expansion joints is missing... The loss of this extraction line expansion
joint not only cost $25,500 per month in lost efficiency, but the unit also lost 4.5 MW of
capacity as a result. Courtesy: Black & Veatch
Indicated total flow dropped unrealistically, at same time as Mill
4D amps and dP increased. Probably pushing too much coal for
the PA flow.
2. The trends are clear. It was obvious something was wrong with the 4D mill, but
what? Source: Black & Veatch
NUHR by measured coal flow dropped unrealistically low, so measured coal flow
must really be lower than actual flow rate.
Problem went away when Mill 4D was out of service,
so probably is the 4D feeder flow rate.

http://www.powermag.com

POWER February 2014

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