Articles

Tetra In Action #9 - October, 2017

2018 Spring/Summer Training Schedule Announced

Tetra Engineering announces the 2018 spring/summer training schedule! Join us in Deer Park Utah, USA in May or Sophia-Antipolis, France in June for HRSG & Combined Cycle training. See our training page for more details. 

course

 


HRSG Inspections - The Key to Reliability

At Combined Cycle Power Plants the Heat Recovery Steam Generator (HRSG) is an easily-overlooked, but key component, providing steam to the steam turbine and to attached process steam hosts.  While base-loaded HRSGs tend to be the most reliable - cycled or two-shifted plants suffering from accelerated damage - the importance of allocating sufficient resources to maintenance of the HRSG is often only realised in hindsight.   Even a simple visual HRSG Inspection during an outage can provide useful information about the how the HRSG is aging and what maintenance should be planned to ensure ongoing reliability.  Many have experienced the sudden drop in reliability that comes when a neglected HRSG begans having tube failures in one area, causing frequent shutdowns that later aggravate other incipient problems that could have been avoided by simple performing a Visual Inspection, and taking remedial action early on.  Tetra Engineering has been performing HRSG Inspections for over fifteen years - over 650 Inspections to date! - and provides an integrated service that supports Owners and Operators throughout the full HRSG life-cycle.  In addition to the HRSG Inspections we also perform HRSG Condition Assessments, in which we review not only the present condition of the HRSG Unit but also how historical operation has affected its integrity. 

As part of its HRSG Life Management services, Tetra also draws on its unique skill set, including extensive field experience and engineering analysis, to assess the HRSG's susceptibility to certain damage mechanisms (e.g. Fatigue, Creep, FAC, Corrosion) and produced customised HRSG Inspection Plans. Those plans can be used by inspectors and NDT-teams during plant outages to target HRSG Inspections where damage is most likely to be found.

For more information on HRSG Inspections and Inspection Planning, see our Field Services page or contact Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser. for USA or Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser. for Europe/Middle East/Asia.

  


Technical Tidbits from the HRSG Inspection Planning Guide

Thermal overstress is generally associated with the high temperature sections of the HRSG (HP Superheater and Reheater).  Flow starvation in a tube relative to its neighbors results in the tube metal temperature approaching the gas temperature.  In that case, tube-to-tube differential temperatures may exceed 500°F (260°C).  The enormous thermal stress that results exceed material yield stress and cause permanent bowing…  

bowed tubes

If you are interested in the full version of the HRSG Inspection Planning Guide (2nd edition) contact Ms Christine Vallon at Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser..  

 

How do GT Upgrades Impact your HRSG?

OEM upgrade packages to gas turbines (GT) can significantly improve performance, operational flexibility and increase outage intervals. In combined cycle power plants, the impact of these upgrades should also be considered for the HRSG where the design was based on the original GT performance.

Common changes that impact the HRSG include :

  • More efficient operation of the GT at lower load (lower flue gas mass flows, higher temperatures)
  • Modifications to exhaust gas profiles at various loads
  • Duct burner firing characteristics
  • Changes to fuel fired
  • Increased outage intervals

 

Tetra Engineering can assess the impact of changes in GT performance on the HRSG and help optimise O&M activities.

See here for our short flyer or contact us for more information:

For US, Central- and South America: Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.

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Thermal Plant Simulation

 Advanced Software for Power Plant Simulation 

Power plant

How a High Fidelity Thermal Plant Simulation Package Can Help Your
Engineering Group Keep Your Plants at Peak Productivity.

 

Tetra Engineering Group, Inc. and KED, GmbH have partnered to offer the industry's most advanced steam plant simulation package for your central office engineering team. 

The Power Plant Simulator and Designer system (PPSD) is a complete high fidelity plant and steam generator offering. Used by many OEM’s worldwide it is also a complete and independent system for plant operators and owners.

No matter what kind of thermal plant you operate, Conventional Coal (sub and supercritical), CFB Coal, IGCC Coal, Gas Turbine Combined Cycle, MSW boilers, package gas and oil systems, ORC heat recovery systems and solar hybrids, PPSD can give you the answers you need. Not only the overall heat balance and performance, but component performance details as well for both steady state and dynamic plant operation. This allows your staff to support levels of troubleshooting and modification engineering at lower cost and faster turnaround.

The PPSD system can also be easily integrated into any kind of “Digital” plant system or information cloud you might have.

Tetra Engineering has over 25 years of experience in supporting all types of thermal plants during design, development, operation and uprating. We use PPSD regularly in all phases of plant evaluation.

As a licensed representative of KED for PPSD as well as a key development partner we provide complete support to operating plant PPSD users. We can offer a complete package to get you up and running quickly. This includes: 

  • Corporate PPSD Licenses and Support (including upgrades and technical support). 
  • Initial Training of system users Development of initial plant models for your system (anywhere from one to several models for complete design and monitoring). 
  • Development of Operational Packages for the plant models to perform any number of key tasks such as performance trending, component life tracking, generation of unmonitored alarms using “hidden” data. 
  • Integration with “Digital plant systems”.

Contact Tetra today if you are interested in having your own in-house capability for this type ofanalysis. We can provide you with details of PPSD licensing, training and technical support.


For information contact:

North and South America:

David Moelling, +1 860 217 9331, Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.

Europe/Africa/Middle East/Asia: 

James Malloy, +33 4 02060254, Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.

 

Packaged Boiler Services

Engineering Services for Package Boiler Troubleshooting 

IMG 0229

Tetra Engineering Group, Inc. can provide complete engineering support for procurement, operations, maintenance and troubleshooting of your package boiler in auxiliary or primary steam service.
 
Our capabilities include:
  • Thermal Performance Assessment and Analysis for any type of pre-heating, process or other application. Both static and dynamic analysis of steam production, temperatures, circulation flows and gas side conditions can be evaluated.
  • Steam velocities and other impacts of lower pressure options as well as use of alternative working fluids such as glycol are easily handled.
  • Pressure part integrity and failure analysis for boiler tubes, piping and drums.
  • Water Chemistry and Steam Quality Support.
  • FGR, Fan and Ducting Design, Maintenance and Troubleshooting.
  • Field Inspection of Boiler Fire-side and Water-side conditions.

Contact Tetra today if you are interested in these Package Boiler Engineering Services.

For more information, please contact

North and South America:

David Moelling, +1 860 651-4622, Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.

Europe/Africa/Middle East/Asia: 

James Malloy, +33 4 02060254, Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.

Tetra In Action #8 - June, 2017

Grade 91 Piping Risk Assessment

Higher demands on outlet steam conditions has led to the increased use of modified low alloy materials (9-12% Cr), such as Grade 91. The superior high temperature material properties of these types of steels (strength, fatigue resistance, creep resistance, improved steam oxidation resistance) gives the designer advantages with respect to boiler reliability and thermal performance. There are many advantages of using this type of material; however, the long-term integrity has been an industry-wide concern ever since the first installations occurred. Tetra Engineering recently published an article in the Engineering Failure Analysis journal titled "Premature Grade 91 failures - worldwide plant operational experience" presenting our experience of premature Grade 91 failures from North America, Europe, the Middle East and Asia. If you are interested in a Grade 91 risk assessment, contact Peter Jackson (Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.) for North/Central and South America or Andreas Fabricius (Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.) for Europe/Middle East/Asia.  


Thermal Simulations using PPS&D

Power Plant Simulator & Designer (PPS&D) provides state-of-the-art capabilities for modeling and simulating the operation of nearly any type of thermal power plant. Originally developed by KED GmbH in Germany for use by boiler OEMs in their detailed design work, PPS&D has since been used by numerous clients worldwide for simulating the operation of many types of boilers and thermal power plants.

  • Natural & forced circulation boilers, both sub- and super-critical

  • Pulverized coal boilers

  • Combined cycle power plants, heat recovery steam generators including once-through and Benson designs

  • Municipal waste incinerators

  • Fire tube boilers

  • Fluidized-bed combustion boilers

 Model Steady-State and Dynamic Boiler Operation

PPS&D is available in a basic version for performing steady-state simulations of plant operation. The enhanced version adds dynamic simulation, allowing testing and integration of key steam cycle control functions, and evaluation of system tran­sient (startup, shutdown, process upset) response.

hrsg waterside triple pressure

Waterside scheme of triple pressure HRSG

More information about thermal simulations can be found here.

  


HRSG Inspection Planning Guide Snapshots

Tensile overload tube failures have become more common with the introduction of the larger combustion turbines that are typical of new combined cycle power plants.  These failures are predominantly in reheater and superheater tubes, where inadequate drain capability exists during startup/shutdown or where desuperheater spray valves are not functioning appropriately.  Desuperheater spray valve hardware and control logic have both contributed to these failures.   

Effective inspection techniques for this damage mechanism depend on the severity and can include:

  • Visual
  • Dye Penetrant
  • Magnetic Particle
  • Radiography

If you are interested in the full version of the HRSG Inspection Planning Guide (2nd edition) contact Ms Christine Vallon at Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser..