With real-time competitive electricity markets ERCOT, PJM,
New York ISO, and Midwest Independent System Operator (MISO), there is now a
clear financial incentive for coal-fired power stations to implement more
advanced process control to lower emissions, reduce costs, and sustain or
improve heat rate and plant productivity. This session offers a visionary, yet
practical, advanced process control “platform” that integrates more
sophisticated sensors (such as on-line coal analysis, air and fuel flow devices,
and others) and final control elements, and key software pieces (such as
optimization software, cost of cycling software, plant information system),
into the distributed control system (DCS). Such a system is more capable of
handling the dynamic process variations that occur when multiple process and
financial optimization goals must be achieved simultaneously and allows
real-time costs to be aligned with real-time prices in the market. Each author addresses a component of the
advanced “platform, followed by an interchange among the authors and audience
about how these components are integrated into a system, benefits to
owner/operators, and technical challenges.
P038-“The Role of On-line, Real-time
Coal Analysis in Advanced Process Control & Optimization”
Steve Smith,
MS, CoalSmith Consultants
Coal quality has a major impact on power plant
reliability and performance. Instruments
for real-time analysis of coal quality have been used mainly by coal producers
for blending and specification monitoring.
More recently, there has been increasing interest in integration of real
time coal analysis into power plant controls.
Barriers to entry and potential aids to adoption of time coal analysis
will be presented and we will report the results of dialogues with plant
owner/operators. Experience with online
analyzers and in-depth case studies, differences in analyzer designs, state of
the art control and automation systems using real-time analysis, and a vision
of integration of real-time analysis into intelligent computer-based financial
optimization processes will be presented.
Neutron and gamma based elemental analyzers can provide valuable
data to improve combustion control systems in the boiler, as well as emissions
controls like precipitators and scrubbers.
Looking forward, we envision intelligent integration of real-time coal
analysis into the financial market pricing controls, so that real-time
financial optimization of the use of coal, the fossil power plant's largest
variable expense, can become a reality.
The speed, ease of integration, and reliability of these analyzers has
reached a stage where owner/operators can realize the potential financial and
reliability rewards they are seeking.
P039-“Using Real-time Cost of Cycling
and Damage to Optimize Plant Performance”
Steve
Lefton, Aptech Engineering Services Inc.
This
presentation discusses concepts and technical details supporting a real-time
cost of cycling and equipment damage software used to calculate total plant
maintenance costs. The program incorporates key readings of temperatures,
stresses, and flowrates from all major plant sub-systems and components into
calculation routines that account for the interaction of (a) cyclic damage from
transient operations, and (b) creep damage from steady-state (baseload)
operations. Screen displays, unique color-bar “thermometers,” include up to 15
key operational parameters (absolute values and rates of change), including
steam and metal temperatures, turbine shell temperatures, flows, etc, which
guide the operator through normal, cautionary, and alarming advisories. These
key parameters are then correlated to boiler and turbine stress levels and
damage, and to past maintenance costs. Such capability helps operators achieve
lowest cost start-ups, shutdowns, and load-following operations. The concepts
behind the software have been applied at dozens of power stations in cost of
cycling studies. The real-time capability is employed at an 800-MW oil/gas
thermal peaking unit in the
P040-“Advanced Process Control
Systems: The New Heart of the
In the evolution of digital control
systems, the inherent processing capability has skyrocketed in the last decade
due to the availability of the same powerful processors, used in home/office
computers, for use in these control systems.
The processes being controlled are typically field device limited in
terms of speed of response; processors in use today can provide logic control,
I/O scanning and other main functions at tens of times faster than the field
can respond.
The latent excess processing capacity
within the digital control systems presents opportunities to take on new tasks
that formerly would reside in servers or other stand-alone processing
devices. From plant performance
monitoring to maintenance monitoring, to asset management, these functions can
now reside fully within the same hardware platform as that being used for
actual process control.
The authors will present a path
showing why and how the plant DCS can and should be looked at no longer as
simply the implementation of process control logic (optimized by another
stand-alone device), but that the decision-making tools (i.e. software tools)
that enhance plant performance, that enhance plant decision making regarding
maintenance, unit dispatch, and other functions that can and should be embedded
in the control system itself. By
harnessing the latent power of the processing capacity of the DCS, operational
decision-making (i.e. business decision making) can become far more real time
and far more meaningful with the ability to instantly understand the commercial
(read profitability) impact.
P043-“Optimizing Turbine Life Cycle
Usage and Maximizing Ramp Rate”
David
Runkle, LCRA, Sim Gideon Station
Changing
market demands have forced older conventional power plants to change operating
philosophy with increased importance on ramp rate. However, faster ramp rates
challenged the conventional control for critical loops like boiler steam
temperatures and increased the potential for high turbine cyclic life
expenditure. Control modifications were undertaken to utilize all available
control parameters to adequately control these parameters and minimize thermal
induced stress on the turbine rotor.
At the
conclusion of the control project, ramp rates of 10%/minute were achieved over
a wide load range. Pro-active control protection has been installed to provide
continuous monitoring of turbine rotor cyclic life expenditure and limit the
maximum expenditure. As a result the unit plays a vital role in addressing
system wide dispatching requirements.
P006-”DCS Integration
for Intelligent Sootblowing”
Sandeep
Shah, Clyde Bergemann, Inc.
The
paper presents automatic closed loop control of sootblowing in power plant
boilers using the DCS integration. Ash and slag deposits in coal fired boilers
contribute to boiler in-efficiency, capacity reductions, and overheated tubes,
which lead to tube failures. Considerable industry research has been done to
improve the conventional time based sootblowing using closed loop controls.
Heat flux sensor can provide the feed back data of ash deposits for furnace
area. The convection pass can be
monitored with thermodynamic models and direct readings from strain gauges. A
stand-alone system solution uses the feedback data to provide a supervisory
closed loop control for an existing DCS based sootblowing control. The
Intelligent Sootblowing (ISB) system uses the monitoring data, algorithms and
sootblowers to derive a supervisory sequence control for the DCS to initiate
most effective sootblowing device, when and where necessary. Industry standard
communication protocol provides seamless integration between the ISB system and
the DCS. This protocol can be Ethernet, Modbus, Modbus TCP, DH+ or Serial. The
paper will describe the existing installations where individual components are
in operation for data monitoring/acquisition, and describes an integrated
system that could combine all these parts to make an integrated intelligent
sootblowing system using DCS based sootblowing controls.