The
trend towards integration of process control and safety systems continues. Are there any unintended consequences
resulting from this integration? What are
some of the power plant safety systems and what standards apply? Do the demographic and industry trends
resulting in loss of experienced control systems engineering and maintenance
personnel at the generating companies pose a risk? Are there I&C technologies that can
improve generating plant safety margins?
P012-“Independency Consideration for Burner Management and Boiler Control
Systems”
Daniel Lee, James Bostick, ABB Inc.
With electromechanical and
electric control systems, a Boiler Control System also called the analog system
provided modulating control to regulate combustion, feedwater, draft, and
temperature control functions. The Burner Management System considered the
digital system provided safe start-up and shutdown of the fuel delivery and
burner systems and misoperation of and damage to these systems. These two
systems were separated because the hardware was assembled from different
products, often from different supplies, and usually implemented by different
engineering groups. With technical advances in programmable control systems and
networks, designers now have the option to integrate in part or in full the
Burner Management System and Boiler Controls System thus, gaining the
functional benefits of the common hardware and software platforms.
This paper presents
historical NFPA 85 perspective to separation, details the advantages and
disadvantages of an integrated system, and discusses current industry
practices.
P033-“Model Predictive Control for Combined-Cycle Startups”
Fernando
D'Amato, GE Global Research, Darrin Kirchhoff, GE Energy, Dean Baker, GE Energy
Increased cyclic duty requirements, higher fuel
costs, competitive deregulated energy markets and stringent environmental
regulations are emphasizing the importance of faster startups for Combined Cycle
(CC) power plant owners. Driven by customer needs, GE revisited aspects of the
startup control and developed a new technology to recapture the machine
entitlement for cold and warm startups in the combined cycle utility market.
A Model Predictive Control
(MPC) technology has been developed for fast combined cycle startups. The new
controller is designed to regulate the gas turbine load at the maximum rate
allowed by the steam turbine rotor stress constraints. The new control
technology developed by GE relies on the use of models for the gas turbine, HRSG
and steam turbine to predict the effect in gas turbine load rates on the steam
turbine rotor stresses. Moreover, the new prediction capability is combined
with very efficient optimization algorithms to calculate the GT loading profile
that leads to the fastest startup. The loading profiles account for the current
state of the unit (including gas and steam temperatures and flows, metal and
ambient temperatures) and are periodically recomputed to adapt to eventual
operating changes and disturbances.
P047 – “Eliminating
Coal Burner Pipe Flow Stoppage at
Donald Andrasik, Mirant Mid-Atlantic, LLC
Tangentially, and other
type coal fired plants may suffer from coal pipe flow reduction or stoppage and
resultant coal pipe/ windbox fires and burner damage. These problems may not
just limit MW production, but can also lead to physical damage and pose safety
hazards. Operating in today’s environment with sometimes competing goals
between coal costs, emissions, and boiler efficiency produces challenges in minimizing
potential burner issues.
Morgantown Generating
Station experienced coal pipe flow problems on both 630 MW Units on a periodic
basis. Many techniques were utilized to detect and mitigate damage, then reduce
and eliminate coal pipe/ burner events altogether. Plant operations desired a
method to detect burner trouble, such that proper measures could be taken to
prevent pipe and burner physical damage. The aspiration was to have needed
information with enough time to make changes: taking mills out of service,
inspecting and cleaning the effected pipes and burners. The detection in time
for action to be useful was a challenge, and several methods were employed
before satisfactory results were realized.
However, timely detection
and mitigation, from the beginning, was not considered the end to this journey.
Instead it was viewed as a step to prevent damage and decrease load reduction
elapsed time until a preventative approach could be found and implemented. In
viewing the plant as a system composed of many sub-systems, boundaries were
identified for the sub-systems in question. Each was explored in an attempt to
appropriately weigh its components’ influence on this process. Our examination
went from the basic checks and corrections on coal delivery to the furnace, to
experimenting with additional control schemes for stopping the elusive burner
issues. This paper identifies some of these schemes, and describes those that
were demonstrated to be significant contributors to the solution.