Using NI Hardware and Software to Build the CMS

Using NI Hardware and Software to Build the CMS-1000 Combustion Dynamic Monitoring
System
"By using NI modular instruments and software, we
significantly reduced the time necessary for tuning a
machine, while making the interface much more
user friendly without sacrificing measurement
accuracy."
- Jordan Pritt, Turbine Technology Services Corporation (http://www.turbinetech.com/)
The Challenge:
Reducing possibly destructive pressure oscillations that could cause accelerated wear, flame flashback, or lean blowout trips in gas turbine
combustors operating at fuel-to-air ratios close to the lean flammability limit.
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Case Study
The Solution:
Using NI hardware and NI LabVIEW software to develop a portable system that monitors combustion dynamics so we can accurately tune and
troubleshoot combustion instability.
Author(s):
Jordan Pritt - Turbine Technology Services Corporation (http://www.turbinetech.com/)
About Turbine Technology Services Corporation
Turbine Technology Services (TTS) offers industry-leading consulting, field, and design services to gas turbine owners and operators worldwide as well as
a wide range of services to utilities, independent power producers, and private sector enterprises. Our engineering consultants deliver proactive evaluation
and solutions for gas turbine owners and operators. Our field engineers focus on implementing our effective designs, providing thorough evaluations,
supervising contractors and suppliers, and coordinating all plant interfaces.
Our mission is to provide gas turbine technology leadership and engineering consulting services on a global scale, supported by our longevity, experience,
and knowledge of solutions leading to the successful management of gas turbine installation and modernization projects, servicing of control components,
and combustion and dynamic tuning for clients’ power plants anywhere our services are needed to maintain operational excellence.
Background
Many plant operators face damage caused by the destructive frequencies in the turbine. Dry Low NOx (DLN) combustors designed to meet today's
stringent emissions regulations must operate at very lean fuel-to-air ratios. Operation at fuel-to-air ratios close to the lean flammability limit makes DLN
combustors prone to dynamic pressure oscillations that can lead to accelerated wear at component interfaces or cracking of hardware; flashback of the
flame into the premixing zone resulting in melting of fuel nozzles or other combustor hardware; or blow out of the flame, resulting in tripping the gas turbine
offline. Regular tuning of the DLN system is required to ensure compliance with emission regulations are met without compromising long-term component
or operational integrity.
The CMS-1000 System
To prevent accelerated wear and mechanical distress of critical components within the turbine, we developed a combustion dynamics monitoring system
using NI hardware and LabVIEW (http://www.ni.com/labview/) software to tune these systems with relative ease. This CMS-1000 combustion dynamics
monitoring system has a compact design and can monitor pressure in each of the multiple combustion chambers within the gas turbine. Depending on the
gas turbine model, we can monitor dynamic pressure in up to 18 combustion chambers. Sensing lines run from each combustion chamber to dynamic
pressure transducers in one of two monitoring boxes, which are located on either side of the turbine. Each box receives half of the inputs.
In addition to the inline pressure sensors, the monitoring boxes also contain dampening coils, a purge system to remove condensation from sensing lines,
and NI 9234 (http://sine.ni.com/nips/cds/view/p/lang/en/nid/208802) dynamic signal acquisition (DSA) modules. The pressure sensors output analog
signals to the NI I/O modules and the NI cDAQ-9188 chassis within each box. The NI hardware and software are configured to synchronize the data
acquisition between the two boxes. The acquired pressure signals are sent via the NI MES-3980 (http://sine.ni.com/nips/cds/view/p/lang/en/nid/203941)
Ethernet Switch to a single laptop computer located in the gas turbine local control room.
The LabVIEW application performs a fast Fourier transform (FFT) on each of the 18 pressure signals, generating a frequency spectrum of pressure
amplitude versus frequency for each combustion chamber. Postprocessing the multiple frequency spectrums provides key amplitude and frequency data
that is required to make tuning decisions on the turbine. Both the spectrums and reduced data can be viewed in multiple graphical formats, enabling the
engineer to easily and quickly determine how to adjust gas turbine fuel and air control in real time. Multiple logging formats also enable the engineer to
easily document changes and generate reports on the tuning performed.
National Instruments Assistance
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National Instruments Assistance
NI provided a great deal of assistance through all the development phases of this project. Prior to purchase, NI helped us understand the process that
would be necessary to achieve our goals and gave recommendations as to which hardware and software combination would provide the best results for
our specific application.
National Instruments also provided the opportunity to learn through training in a classroom setting. Since our software developer on this project had no
previous LabVIEW experience, training was vitally important to get up and running quickly and ensure efficient, high-quality work. The LabVIEW Core 1
training course (http://sine.ni.com/tacs/app/overview/p/ap/of/id/1582/sn/n24:12725/) provided vital instruction, and we could not have completed our project
on time without it.
After purchasing NI products, National Instruments was constantly assisting us in any way necessary, ranging from setting up the connections for data
polling in the hardware to helping with software development stages. NI technical support was an extremely valuable resource. Knowledgeable and
responsive, they took the time to understand what we were trying to accomplish and, at times, suggest alternate ways to reach our goals more efficiently.
Product Benefits
The CMS-1000 is a compact, portable dynamics monitoring system that we can sell as an end product to customers who want to tune their own gas
turbines and also use in-house to provide tuning services to customers not interested in tuning their own units. Packaging the sensors, tubing, and NI
hardware together in the same monitoring box greatly simplifies the field setup of the system, requiring the running of just two cables to interconnect the
three major components: two monitoring boxes and one laptop. LabVIEW software helped us develop a simple, user-friendly GUI as well as data-logging
capability. These software features are of particular benefit in the systems that we sell for customer use.
The CMS-1000 also provides us with an existing platform for ongoing development of a DLN combustor auto-tuning system. The auto-tuning system will
take the existing dynamic monitoring capability of the CMS-1000 and incorporate both stack emissions and turbine controller inputs. An auto-tuning
algorithm will continuously provide feedback to the real-time fuel control adjustments to continually optimize emissions and dynamic pressures during
operation. These adjustments are currently made manually by a combustion engineer at only a discrete point in time. Such manual tuning does not
optimize operation in response to seasonal changes in ambient conditions or degradation of combustor hardware over time.
Conclusions
By using NI modular instruments and software, we significantly reduced the time necessary for tuning a machine, while making the interface much more
user friendly without sacrificing measurement accuracy. We anticipate using National Instruments hardware and software for future combustion dynamic
monitoring systems.
For more information on this case study, contact:
Mitch Cohen
Turbine Technology Services Corporation (http://www.turbinetech.com/)
12661 Challenger Parkway, Suite 250, Orlando, FL 32826
Tel: +1 (407) 677-0813
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The CMS-1000 System
A Side View of the CMS-1000 System
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The CMS-1000 System
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