Tagged With "flexible"

Topic

Flexible rotor -- Turbine or Generator rotor balancing

Mrunal Dave ·
Dear Vib Legends, Looking for your help regarding the Flexible rotor (Turbine or Generator ) balancing. I am having total 10 years of experience (Cat-II Certified Vibration Analyst from Mobius) in Vibration Analysis (which includes power plant and Cement Plant) but had never got an opportunity to balance the turbine / generator rotor. I am very much interested to learn flexible rotor balancing and also ready to invest some bug i.e. books, training institute (in India only) etc. Can anyone...
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flexible coupling run out correction

vikramdeeps ·
Hello , Guys just want to know the allowable run outs for flexible TB woods Dry Flexible spacer couplings ? And where to check it?Any way to correct the radial run out on coupling OR just replaced it?Coupling drawing in attachment
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collector rotor balancing

hamid.mechanic ·
does collector rotor that couples with a flexible rotor 50Hz, is rigid or flexible? and balance process do only mass residual balancing?(iso1940) Keep in mind that collector from one side couple to the main rotor and another side-mounted on journal bearing.
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Re: flexible coupling run out correction

fburgos ·
Runout, where? hub? spacer? its better to be zero. why you whant to change coupling?is there vibration problem, shim pack damage?
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Re: Flexible rotor -- Turbine or Generator rotor balancing

William_C._Foiles ·
Not everyone practicing the black arts of vibration will get an opportunity to balance a turbine or generator. The smaller the size the lower the economic risk. Two pole motors might be a start. Getting access to a rotor kit with a flexible and changeable rotor design could greatly benefit you. Few people start with a turbine or generator for a field balance. Hopefully, you have a good resume of balance jobs (if with a company, your company should be aware of your experience). Other...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

Mrunal Dave ·
Dear Mr William, We have 04 turbine generator sets of 23 MW each (smaller ones of course) and tried to learn the balancing as we have given contract to the third party but as you said it rightly, it is a very rare job and third party guys are also not sharing enough information to fulfill the purpose of detailed learning. That's it for my working with TG sets. I have recently purchased the book "Turbine Steam Path Maintenance & Repair: Volume 1" and found very informative from the...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

Becar ·
I know some people here will disagree but on my opinion the only safe and proper way for bigger TG sets is balancing on the suitable balancing machines. Here are some arguments about it: - risk of damage when the initial unbalance values are high - vibration security shutdown systems - there is no classic ON/OFF button at TG, usually technology behind startup and coastdown is very complex and takes some time (production loss, customer nervousness...) - difficult (unreachable) and dangerous...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

John from PA ·
Well I for one will be in the "disagree" column. It is entirely possible to balance this type machine safely and well in the field. But you have to learn a unique set of skills and think through what you are doing.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

Becar ·
John, it does not depend on your skills only but on the entire customer's operating team. That is why I didn't write: - You need to have special skills (that I suppose should be logic) But ok, I respect your opinion.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

Mrunal Dave ·
Dear Mr John, You are very correct and this skills. But I need everyone's opinion / advice from you all that from where should start learning this ? Please help members. Thanks in advance.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

John from PA ·
Consider some external training... http://www.geoilandgas-bentlytraining.com/ . Once there select "Advanced Field Balancing (NEW)" at about the middle of the page. Note it is being given in Florence Italy from 02 October to 04 October.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

William_C._Foiles ·
John said that it was entirely possible to balance ,... I would say that it is entirely necessary generally to balance large TGs in the field. Take a 10+ bearing TG (or go smaller 6 bearings), at best only individual spans have been high speed balanced in a balance machine. Besides other differences between a balance machine and the real assembly, these rotors have not been coupled, aligned, nor run together.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

John from PA ·
I'm surprised to see you here Bill. Hope all is well with you and family in Houston.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

Ron Stiemsma ·
Other things to think about: Is there access to the balance planes? Do you have the proper weights for each balance plane? What type of instrumentation are you using or have available?
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Re: Flexible rotor -- Turbine or Generator rotor balancing

er.arjun ·
If you are going for turbine balancing then first you have to understand your machine dynamics. If your vibration is very high at critical speed then you have to do balancing to accommodate high vibration in critical stage. If you are doing balancing for steady state vibration then there is separate procedure.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

ALI HAIDERR ·
Dear Dave, To see your post,I remember my old days. I was very afraid at the beginning but Mr.Raflah Stewart helped me a lot so now I be able to do flexible rotor balancing. I advise you that you should start with small machine after that you can do flexible rotor easily. Actually, production loss,and emergency pressure is problematic when you doing for flexible rotor.
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Re: Flexible rotor -- Turbine or Generator rotor balancing

john borycki ·
Been there and done that to 1000 Turbine Generator Units over a 40 year career all across the US and world. Twenty years for OEM's and 20 years as an independent consultant. Units of makes from 1Mw to Nuclear Units 1300 Mw, Takes a good education, great mentoring.field work experience, balance pit exposure,background in rotor dynamics(application), vector analysis,a great reputation, and of course a hot suitcase. John
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Re: Flexible rotor -- Turbine or Generator rotor balancing

spherical ·
@Mrunal, Going back to you first post, you said you need help for flexible rotor and then your equipments are turbine generators units, right? I believe those two do not necessarily mean the same, i.e. that flexible rotors are turbine-generators nor vice versa. Balancing for me has two main bodies, firstly knowing the "science" or the procedure of balancing and second doing/applying it on the real balancing work? Are your concern in the 2nd part only? regards
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Re: Flexible rotor -- Turbine or Generator rotor balancing

spherical ·
For those who said balancing it in the field, did we mean balancing it which includes correction for the flexural mode or just using the rigid balancing technique until unbalance tolerance is acceptable? And follow up question would be, for flexible rotors, when we attain an acceptable unbalance tolerance at the end bearings, does it guarantee stress cause by flexural deflection is also within safe level?
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Re: Flexible rotor -- Turbine or Generator rotor balancing

William_C._Foiles ·
Proper balancing means obtaining acceptable vibration all the time (Some may have an exception or two.). Say you have the vibration acceptable at the bearings for all speeds and conditions, then from the physics (science) the vibration is controlled at every point of the rotor system (and elsewhere). It is not possible to have the vibration controlled at one point for all speeds without having it controlled. Given practicalities, there is no such thing as a pinned condition. Even there were...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

spherical ·
Bill, Thanks for your response. Firstly, I don't question the effectiveness of in-situ balancing. In-fact if it can be done safely and economically, I definitely agree, it will the best way to achieve the desired results. Now, going back, regarding in-situ balancing of flexible rotor, would you always recommend to always address the flexural modes as well or just balance it far below/above the critical speeds? What happened to the rotor deflection after passing the critical speed? I remember...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

john borycki ·
Spherical: For flexible rotor balancing you always address the flex mode of the shaft while increasing speed to operational speed. Here in the States we term that shaft resonance curves or commonly referred to as Bode Plots. In the field you are sometimes limited to the number of balance planes available for Field Balancing (on site balancing) especially on Generator Fields. Ideally you should have at least 3 balance planes to address the different type of shaft modes (criticals). This would...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

John from PA ·
I would be highly suspicious that the balancing, even at low speed was not done correctly. There are three types of balancing applied to induction motors that are dependent on their "vintage". You can balance with a full key, half key or no key. Siemens for instance clearly marks how the original balance was accomplished on the nameplate; "F", "H" and "N" being full, half, no respectively. Half key balancing has been standard in the industry since about 1998. Depending on the method applied...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

spherical ·
@john borycki As you said the flex mode is always being address then do you still think in-situ balancing is conveniently economical considering we might face problem having access in the center plane? With above quote, 2nd paragraph; do you not think, this is really design in this matter so that during passing far the resonance, heavy spot counters the motion response? regards
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Re: Flexible rotor -- Turbine or Generator rotor balancing

spherical ·
I miss your reply as I was writing my response to other john I have not tracked well all the balancing activity of that shop, I am not sure if the balance tolerance was kept very low or they do something else like adding balancing planes. regards
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Re: Flexible rotor -- Turbine or Generator rotor balancing

john borycki ·
Depends what you are balancing , Turbine , Generator, and of course the design by OEM. Field balancing can be economical as I have done it for 40 years. Hard to believe! Numerous times it was performed with other plant issues such as boiler outages, valve outages, or other matters that required downtime. Not specifically to address the vibes.Also depends what your vibe issues are. If a center plane is not available, and you've performed bucket work at or near the Center plane or Rewound a...
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Re: Flexible rotor -- Turbine or Generator rotor balancing

spherical ·
Are those flexible rotors type and at what speeds did you do balancing? Regards
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Re: Flexible rotor -- Turbine or Generator rotor balancing

john borycki ·
Speeds are too numerous to mention. Briefly, on 3600 RPM Units anywhere from 1200 RPM to 3600 RPM with many vibe and speed checks in between. The 1200 RPM balancing incident was a unique experience on a 3600 RPM Low Pressure Turbine Rotor. JB
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Re: Flexible rotor -- Turbine or Generator rotor balancing

William_C._Foiles ·
In my opinion, considering all modes SHOULD be done when balancing. One may pass through these on a motor start without issue, but one may not coast down so quickly. Motor balancing: One issue is that it is done by motor people (any complaints here!). I've seen some poor (worse than poor) practices. Often, one will get an at speed balance if done on the test stand. This can lead to issues mentioned here. Of course, one may have an often found issue of the motor running near or on a critical.
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Re: collector rotor balancing

Walt Strong ·
It is another mass on a flexible rotor. Balancing it may or may not affect vibrations at other bearings. Have you contacted a knowledgeable person with OEM? If vibration is considered high on the bearings, then look for mounting eccentricity and resonant bearing housing before considering trim balancing. Walt
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