Take note: User registration for the 501F Users Group 2018 meeting opens soon

A valuable component of the upcoming 501F Users Group conference at the Hyatt Regency Grand Cypress (Orlando), February 25 to March 2, 2018, is the Vendorama program, scheduled for the first day of the meeting ahead of the vendor fair. It gives attendees access to live presentations by dozens of products/services providers offering O&M solutions.

At the 2017 conference, 37 companies made 41 technical presentations ranging from 30 to 50 minutes each to bring users up-to-date on proven technologies of interest to the 501F community. The program matrix—seven time slots in each of six rooms, running from 9:30 a.m. to 4:00 p.m.—allowed each attendee to participate in up to seven presentations vetted for technical content by the organization’s all-volunteer steering committee.

The accompanying sidebar illustrates the diversity of subject matter provided in the Vendorama program. Several presentations summarized below provide perspective on the quality of the information disseminated. Discussion on some of these topics is unique to the 501F Users Group annual conference and another good reason to sign up for the 2018 meeting as soon as user registration opens in early November. Vendor registration opened September 6.

Owner/operators of 501F gas turbines can access presentations identified in the sidebar via the organization’s website; click on “Conference Materials.” Since you must be a registered user to get this information, there may be an additional registration step if you’re not an active member. There is no registration fee.

Improving back-up liquid-fuel-system reliability, JASC 

Reliable operation of dual-fuel gas turbines on oil demands that owner/operators protect against coking of oil in fuel-system valves and piping. Active cooling is one solution available to users for assuring both reliable starts on liquid fuel and reliable fuel transfers from gas to oil.

“Cool valves, piping improve engine reliability when called to burn oil,” discusses several cooling options offered by JASC. One of these, the so-called “thermal clamp,” was introduced as that article was in preparation. Early results available from the first commercial installation point to success both in protecting against coking and eliminating the need for “verification” firing of oil monthly to confirm liquid-fuel system reliability.

With the company’s latest system configuration consisting of rerouting fuel piping, incorporation of heat-sink clamps to keep fuel lines cool, water-cooled fuel controls, and component connections which don’t use O-rings, JASC now offers the capability of running on liquid fuel at semi-annual intervals, or longer, without sacrificing back-up liquid-fuel system reliability.

In the first test of this latest configuration, a 7F gas turbine operated on liquid fuel during commissioning of its fuel-system upgrade in April 2016. The unit operated exclusively on natural gas over the next nine months, burning oil only during the second week of January 2017. The turbine started and operated on liquid fuel without incident.

A typical F-class unit needing to confirm oil firing capability would have paid approximately $30,000 each month the test was conducted. Thus, not having to run tests for nine months after the upgrade was completed saved about a quarter of a million dollars.

Next generation turbine insulation, ARNOLD Group USA LLC 

ARNOLD Group’s single-layer insulation system was said to be state-of-the-art technology capable of solving all known insulation-related problems associated with the operation and maintenance gas and steam turbines.

During operation, it enables users to decrease compartment temperatures significantly—by more than 50% in some cases—while decreasing fuel consumption and increasing power production. During maintenance activities it reduces outage time and related cost because there are fewer blankets to remove, repair, and replace. Plus, less local insulation labor and less scaffolding are required for outages.

ARNOLD’s Pierre Ansmann said the company guarantees reuse of its insulation system for 15 outages without a decrease in efficiency.

Advanced repair processes for 501F vanes, Sulzer Turbo Services Houston Inc 

First half of the presentation was dedicated to the primary failure modes of 501F vanes (oxidation, thermal distortion, and thermomechanical fatigue), focusing on oxidation. Recall that the degree of oxidation depends on temperature and time, the former controlled by the cooling scheme, explained with a series of excellent drawings.

Laredo Womack, operations manager for the company’s Component Div, said the weakest links in the cooling chain described were the leading-edge air dam and the inner pressure pan/bathtub. Failures generally are caused by a loss of cooling air to the showerhead on the leading edge and/or to the pin fin cooling on the trailing edge. Photos illustrated typical damage.

After passing mention of conventional repair processes (solution, blend, jacking, welding, stress relief, machining), Womack dug into advanced repairs—coupon replacement, core-plug guide replacement, and brazing (wide gap, narrow gap, and preform, or slump, if you prefer). Unfamiliar with slump brazing? It is a method for repairing highly contoured areas on airfoils that have become too thin. It’s benefit: Extend vane life at optimal time and cost.

Drawings detailed how vanes are sectioned for coupon repairs, photos illustrated the repair process—coupon fitting, bracing, throat check, plating, welding, NDT, and re-establishment of cooling holes.

Guidelines for inlet filter selection, CLARCOR Industrial Air Inc

An important takeaway from the presentation’s first dozen slides was that poor air filtration accounts for approximately 60% to 80% of overall GT losses. That statement alone was incentive to listen to Dan Burch, who reinforced his presence by way of example: An F-class gas turbine operating 8000 hours annually and selling power at $50/MWh pays a penalty of about a quarter of a million dollars for every 1 in. H2O increase in pressure drop across the inlet air system. The obvious message: Dirty filters can cost you big time.

Following an overview of filter ratings and typical industry tests, he suggested several other tests you should ask prospective vendors to conduct on their products to enable an informed buying decision, including these:

      • Dust and salt removal efficiency.

      • Humidity, mist, and fog testing.

      • Burst tests, both wet and dry.

      • Dust holding capability.

      • Rough handling testing.

      • Hydrophobic performance with loading.

      • Temperature-extreme suitability.

      • Gasket testing.

      • Overall performance (beta site trials and mobile test rigs).

Burch then conducted a side-by-side comparison of HEPA filters made of microfiber glass media and ones made with a layer of d-PTFE membrane. He concluded the former as better able to handle the moisture than the latter.

Online transformer oil conditioning, C C Jensen Inc

Transformer oil conditioning was only part of Axel Wegner’s presentation, which also covered in overview fashion the conditioning of steam- and gas-turbine lube oil, control fluids, cooling-tower fan gear oil, and diesel fuel in storage.

The last was a new entry in the conditioning playbook for powerplant oils. Most users are familiar with treatments for lube and control oils, but the conditioning of diesel oil at a dual-fuel plant was unknown to many. At the plant Wegner described, one equipped with a nominal 1-million-gal storage tank, the gas-supply failure plan called for running gas turbines for three to five days three times annually.

The oil was not up to the quality required for GT use and the plant had no choice but to remove water, microbial contamination, and particulates from the fuel before burning it. Using a filtration system similar to that used by C C Jensen for turbine oil was a viable solution. In only one pass through the filter, water content was reduced from 702 to 71 ppm (1500 liters of water removed from the oil), 2-micron particle contamination was reduced from 28,860 to 17,041, and sodium and potassium levels were reduced below recommended levels.

Oil sampling: Particle counting, Hy-Pro Filtration 

Selecting a sample port for trending particle count was the focus of this presentation, which is recommended viewing (by the editors) for anyone responsible for oil sampling, because of its practical approach and level of detail.

The main point is that you can acquire an oil sample to check fluid health and chemistry (acid number, viscosity, additive package condition, dissolved metals, water, oxidation) from virtually any location in the system. However, locations for trending particle count are limited. The two recommended were at the lube-oil pump outlet upstream first filter assembly and from the reservoir cooling a polishing loop upstream filter assembly.

Location of the sample port is important, too, with the middle 50% of the pipe the optimum. Several slides describing placement are a “how to” for those who have not performed this task previously. A couple of case studies with charts of sample data were provided.

Benefits of maximum access for borescope inspections, Advanced Turbine Support LLC

This is a must-view presentation because the story is told in pictures illustrating the level of detail possible for accurate damage assessment when adequate access is provided for borescope inspections. A few of the many components shown include the following: inlet-strut cracking, compressor impact damage, locking-key wear, aft movement of compressor blades, diaphragm wear buttons, hook-fit wear measurement, missing tie wire in the combustion section, cracks in rocket swirler supports, turbine-blade platform cracks, etc.

Separate sections of the presentation covered the following:

      • Exhaust-strut inspections—visual damage assessment, dimensional checks, liquid-penetrant and phased-array inspections of welds—made possible by access gained through the exhaust duct.

      • Compressor spindle bolt in-situ inspection using advanced phased array. Sectoral image and waveform scans illustrate the power of the technique.

Lifecycle cost considerations for GT inlet filtration systems, Camfil Power Systems

The lifecycle cost analysis provided for a high-efficiency, medium-velocity air filtration system incorporating weather hood, turning vanes, pre-filter (F6, F7), and final filter (F9, E10) illustrates how you might perform an in-house analysis to aid management decisions.

Inputs to the equations provided include gas-turbine capacity, revenue from power produced, cost of fuel, cost of downtime, frequency and cost of compressor washes, and filtration costs—including disposal fees.

The case study profiled considered lifetime costs (replacement filters, etc) and identified key cost drivers. The summary chart of results in this instance showed a financial benefit for using a pre-filter and E10 final filter over an H14.

501F turbine update, Emerson Automation Solutions 

Tom Zuvlis spent his time at the front of the room discussing strategies to optimize the performance of 501F-powered combined cycles equipped with Ovation control systems. He focused on a suite of advanced applications that individually, or in various combinations, can achieve the following:

      • Reduce fuel use on cold starts and on warm and hot transitions.

      • Improve startup consistency and ensure on-time breaker closure.

      • Reduce plant chemical consumption.

      • Improve shutdown procedures to bottle-up the unit for fast, efficient restart.

      • Reduce metal fatigue.

      • Improve overall plant reliability.

Aeropak I and II stator rewind preparedness, AGTServices Inc 

When you think your generator rewind project is well-planned, that’s when to access Jamie Clark’s presentation and go through his 40-plus slides to identify what you’ve forgotten. This presentation is a checklist which may be worth its weight in gold to anyone lacking rewind experience. Even if you sat in on Clark’s presentation you likely couldn’t take notes fast enough take down all the best practices and lessons learned. 

The first slide confirms why you’re considering a stator rewind: the effects of age, increase output, design deficiency, or winding damage, etc. Several photos serve as a wake-up call, illustrating insulation breakdown experienced by others. Next slide: A list of general outage considerations—including plant configuration, other shaft-line work planned, stator design, laydown space, crane availability, etc.

Then comes the nitty-gritty, slide after slide. A couple of examples to encourage viewing of the presentation:

      • Sure, you have lots of space, but it’s outdoors. Where do you store your field? Significant planning/logistics are required to provide sufficient environmental/ambient protection, FME, etc.

      • Most combined cycles require “working at height.” This can present logistical challenges for field removal. Are there axial impediments to crane access to the field? Many units have buss work running axially out of the collector end, adding to disassembly work, etc.

      • The field removal “platform” may become your “dance floor” for the rewind. But some additional costs (such as equipment rental charges) may offset the perceived benefits and saving from less scaffolding, etc.

2017 Vendorama presentations

AAF International, HEPA filtration and the issue of corrosion

Advanced Turbine Support LLC, Benefits of maximum access for borescope inspections

AGTServices Inc, Aeropak I and II stator rewind preparedness

Allied Power Group, 501FD2/3 Row 4 turbine-blade repair quality

Alta Solutions Inc, Next generation vibration protection systems

American Chemical Technologies Inc, Eliminating varnish in GT systems

Arnold Group USA LLC, Next generation turbine insulation

Brace Integrated Services Inc, Best practices: Freeze protection and winterization programs

Camfil Power Systems, Lifecycle cost considerations for GT inlet filtration systems

C C Jensen Inc, Online transformer oil conditioning

CLARCOR Industrial Air Inc, Guidelines of inlet filter selection

Coverflex Manufacturing Inc, Coverflex exhaust wall seal

Crown Electric Engineering & Manufacturing LLC, Circular non-seg bus duct

EagleBurgmann Expansion Joint Solutions, New expansion-joint design for 501F turbine exhaust

Emerson Automation Solutions, 501F turbine update

Frenzelit North America Inc, CT exhaust expansion joints and penetration seals

GE, Innovative 501F repair capability; Pressure wave technology for HRSG cleaning

Hy-Pro Filtration, Oil sampling: Particle counting

Industrial Air Flow Dynamics Inc, Expansion-joint failures and cracking RCA review

Intertek Group plc, Asset performance management tool for combined cycles

JASC, Improving back-up liquid-fuel-system reliability

Lectrodryer LLC, Generator auxiliary upgrades with emphasis on hydrogen safety

Mee Industries Inc, Maintaining/upgrading inlet-air fogging systems

Mitsubishi Hitachi Power Systems Americas Inc, Parts strategy to reduce lifecycle cost; Turbine section component repair

National Breaker Services, Switchgear life extension

National Electric Coil, What maintenance matters?

Nederman Pneumafil, Dealing with moisture for air-inlet filtration technology

Parker Hannifin Corp, Simplifying GT piping and tubing connections

Peerless Manufacturing Co, Advancements in SCR technology

Pioneer Motor Bearing Co, Fluid-film bearings

PowerPHASE LLC, 8000-hr parts life extension on a 501F using dry-air injection

PSM, Ansaldo Energia Group, PSM controls capabilities for 501F

SETPOINT™, Intelligent sampling and storage of vibration waveforms

Sulzer Turbo Services Houston Inc, Advanced repair processes for 501F vanes

SVI Dynamics, Common problems with CT exhaust liner and silencer systems

Tetra Engineering Group Inc, Impact of creep-fatigue cracking in Grade 91 pressure parts

TOPS LLC, Outage preparation

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