Category Archives: Performance Monitoring

Instrumentation Issues

Welcome back! It’s been a while since I’ve posted here. Been buried with client requests… there are worse problems to have, I suppose.

This summer’s focus is INSTRUMENTATION.

I’ll be digging into the instrumentation requirements for combined cycle facilities, looking at what instrumentation you’re likely to have on site, what accuracy and uncertainty you can expect for your key performance indicators (such as GT compressor efficiency, ST sectional efficiencies and overall plant net heat rate), and the cost to add instrumentation – especially those items you very likely don’t currently have (such as an accurate weather station or gas chromatograph).

So… please post any suggestions, comments or questions regarding instrumentation here on this blog entry, or jot me an email direct.

I’d love to hear from you about what your current issues are regarding instrumentation:
* How often do you calibrate devices not required by controls?
* What manual inputs do you make (or try to make) on a regular basis? (i.e. HHV)
* What roadblocks do you run into when trying to add instrumentation?

And check back here for updates. Hopefully more often than once a year!
I hope you all enjoy your summer.
-Tina

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Power Workshop

I will be presenting a seminar on how to calculate key performance indicators for combined cycle power plants at this year’s ASME Power Conference. 

For more information on the conference – including how to register for the workshop, see ASME’s website.

Looking forward to seeing many of you next month!

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7FA issue with liquid fuel lines

 Combined Cycle Journal posted an article yesterday (4/14/11) regarding a potential safety hazard on the 7FA liquid fuel lines – even when the unit is not a duel fuel unit, and fired natural gas only.

A leak around a blank flange on an unused liquid fuel port led to a pressure reduction in the combustion chamber  – which allowed the flame to move back and attach to the fuel nozzle itself.  Once the flame was attached, severe material deterioration occured.

The details, including pictures and recommendations are included in their article, here.  If you operate any 7FA’s – on any fuel – I recommend you take a look at the article’s findings.

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Improving GT Availability

This month’s Power Engineering magazine highlights one of the best papers of the 2010 Power Gen Conference.

See page 54 in Power Engineering, February 2011.

The whole paper can be found at PowerGenWorldwide in PDF form.

The paper gives details around MHI’s experience with increasing the availability of the M501F, but the information could be extrapolated to apply to all industrial gas turbines, and other equipment as well.

The highlights of the paper include planning for gas turbine performance from four difference angles of attack:

  1. Design
  2. Scheduled Maintenance
  3.  OEM Support
  4. Continuous Monitoring

Better designs, which include planning for maintenance, can lead to less downtime.  Especially when the designs lead to increased part longevity.  Time between repairs and/or replacements is on the rise as better coatings and materials are available.

Using experienced crews and well-tested procedures for your scheduled maintenance can lead to shorter outages overall, so your plant can get back on line – or at least available to be on line – faster.

OEM support, especially for newer designs, can improve troubleshooting efforts and may lead to upgrades in parts or services which further reduce down time in the future – especially if the upgrade means a part can operate longer between inspections.

Continuous monitoring – my personal favorite – can lead to finding problems when they’re small, and fixing small problems with a short outage – instead of waiting to find big problems later, requiring extensions on major outages if additional parts need to be ordered.

Monitoring technology is improving every year.  Neural net, or “smart” software can learn how a plant operates, then detect small abnormalities before alarm limits – or even warning limits – are reached.  Expertise is still needed to find the source of the abnormalities and solutions for getting back to ‘normal’ – but overall these new systems are effectively reducing downtime – leading to significant improvements in equipment availability.

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State of the Union 2011

Interesting to note that “Efficient Natural Gas” is considered a Clean Energy Source.  How do you know if your facilitiy is “Efficient”? Visit the link below to download the actual fact sheet PDF.

-T

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From: State of the Union 2011 Fact Sheet: Clean Energy Standard (CES) | Alliance to Save Energy.

State of the Union 2011 Fact Sheet: Clean Energy Standard (CES)

white house
Author(s): Miriam Berg
The White House Office of Public Engagement released this clean energy sources (CES) fact sheet, “President Obama’s Plan to Win the Future by Producing More Electricity Through Clean Energy,” the night of Obama’s Jan. 25, 2011, State of the Union address.

According to the fact sheet, a global race is underway to develop and manufacture clean energy technologies, and the United States is competing with other countries that are playing to win. The United States has the most dynamic economy in the world, but Americans can’t expect to win the future by standing still. That’s why, in his State of the Union address, Obama proposed an ambitious but achievable goal of generating 80 percent of the nation’s electricity from clean energy sources by 2035.

Meeting that target will position the United States as a global leader in developing and manufacturing cutting-edge, clean energy technologies. It will ensure continued growth in the renewable energy sector, building on the progress made in recent years. And it will spur innovation and investment in U.S. energy infrastructure, catalyzing economic growth and creating American jobs.

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Power Plant Forum

I’ve been tossing around the idea of starting a forum for discussing power plant performance issues… so I ‘Googled’ “Power Plant Forum”… and whaddya know – there IS one!

http://www.powerplantforum.com/

I just signed up – looks like there are more than 16,000 members.
I haven’t browsed around too much yet, but I’m hoping I can add some value there and connect with some new power plant professionals.

Any one here a member?

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Calibration Gases

There’s a great article in this month’s Power Engineering magazine:
Proper Calibration of Gas Analyzers” by Terrence Kizer.
(October 2010, starts on page 22)

It points out some of the options for CEMS calibration gas cylinders and how the analyzers use them to monitor for analyzer drift.

You should also check on your natural gas chromatograph calibration gas cylinders (if you have an onsite chromatograph) – the closer the calibration gas is to your actual pipeline gas, the more accurate the resulting analysis will be. If you’re still using the same calibration gas determined during site development, you might want to take a second look. Pipeline gas can shift from season to season, and if your calibration gas is significantly different than actual, the accuracy of the reported heating values will be affected.

If your chromatograph is also used for billing purposes – you’ll want to make double sure the calibration gases are correct. Even a 0.2% increase in a plant fuel bill can be a very large number!

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Instrument Calibration

A colleague recently asked a very important question:
How often should instruments be calibrated?

Many sites have requirements for calibration on certain instruments – such as fuel flow meters used for emissions reporting. But what about the rest?

Any sensor – temperature, pressure, flow, etc. – which provides input into your control system should be monitored regularly for accuracy. Things such as compressor inlet temperature, compressor discharge pressure and exhaust temperature – to begin with – all play a part in the load control of every type of gas turbine.

Annual calibrations are normally a good starting point – they provide you with a baseline for how each instrument changes over time. Reviewing these calibrations will give you a better understanding of how the working environment is impacting each sensor. In certain high stress applications – such as compressor discharge pressures on peaking units – calibrations and instrument adjustments may be needed more frequently than once a year. In low stress environments – such as cooling water temperatures – annual may be more than needed. But, if you lower the frequency of calibrations to less than annually, you may need to adjust your low-level alarm points to more readily catch instrument drift failures.

Please share how often you calibrate your site instrumentation here – I’d love to hear what your policies are. Do you calibrate all sensors or just a select few? Annually? Semi-annually (i.e. during each spring and fall outage)? Or “as needed”?

Do you utilize software tools, such as pattern recognition, to adjust your instrument calibration schedules?

I look forward to reading your replies.

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Consistency

The word of the month is apparently Consistency.

I keep hearing about how consistency makes everything better. Communication, accounting, sales & marketing, diet, exercise… the list goes on.

So, let’s add another one:

Consistency makes for a better Performance Monitoring Program.

How?

If you are consistent in looking at (i.e. monitoring) the performance of your equipment every Wednesday morning – then you’ll start to intuitively know what the answer should be. You’ll recognize when the pattern varies from the norm much faster than if you only occasionally look at performance – sometimes once per day, other times just once per month. Small variances can easily be missed.

If you are consistent in your Performance Monitoring efforts those small variances become more obvious as you become more comfortable looking at the data. Keeping small variances in line with a water wash or an instrument calibration is a lot easier than fixing a large problem – or even finding a large problem if more than one instrument has drifted outside the expected range of operation.

When multiple data readings are suspicious, it’s a lot harder to determine the true measurements. If you can catch one bad data point at a time, large problems become less frequent – or so obvious that you’ll know when maintenance needs to get involved – immediately!

How consistently are you monitoring your performance?

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