ger-3706d - steam turbines for industrial applications

GE Power Systems

Steam Turbinesfor IndustrialApplications

J.E. EstabrookR.H. LegerGE Power SystemsMarlborough, MA

GER-3706D

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1IST Business . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1IST Business Product Line. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Geared Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Mechanical Drive Steam Turbines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Directly Connected ISTs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Feed Pump Turbines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Geothermal Steam Turbine Generator Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Modular Product Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Inlet Sections and Casings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Valve Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6New Inlet Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Steam Utilization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Non-Condensing Turbines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8District Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Improvements in Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Axial Exhausts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Turning Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11SPEEDTRONIC™ Mark VI Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Mark VI TMR Control Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12HMI System Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13VF Series Fluid System Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Full-Feature Designs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Simple, Cost-Effective Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Operational Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Performance and Economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Simple, Cost-Effective Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Environmental Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Ability to Meet Site Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Application Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Steam Turbines for Industrial Applications

GE Power Systems ■ GER-3706D ■ (10/00) i

Turbine Factory Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Features of the Packaged Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Axial Exhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Improved Turbine Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Reduced Building Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Reduced Installation Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Reduced Installation Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Cost Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Design Standardization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Increased Design Standardization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Increased Design Automation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Sourcing Partnerships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Manufacturing Initiatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Increased Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Project Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


GE Power Systems ■ GER-3706D ■ (10/00) ii

IntroductionGE has been producing industrial steam tur-bine (IST) drive systems since the early 1900sand has placed more than 5,000 units into serv-ice around the world. Throughout this time,the performance, reliability and cost-effective-ness of these turbine systems have improvedcontinuously through product and packaginginnovations.

This effort continues today with the formationof the IST unit within GE Power Systems to pro-vide a broader product line and service capabil-ity to our industrial and small steam turbineusers worldwide (Figure 1).

The IST unit integrates the IST portion of GEPower Systems in Schenectady with that of ourGE Nuovo Pignone unit in Florence, Italy.

This paper presents an overview of the ISTunit’s design approach, current product lineand recent innovations.

IST BusinessThe IST business is based at two main businesscenters in Marlborough, Massachusetts, andFlorence, Italy (Figure 2). Sales and applicationsupport is performed from Marlborough,

Schenectady, and Florence. Detailed engineer-ing is performed in Schenectady and Florence.Manufacturing and assembly centers are inSchenectady, Bangor, Maine, and Florence.Service support is achieved from worldwidelocations.

IST Business Product LineThe IST business product line consists of steamturbine systems, ranging from 3 to 130 MW, thatfollow either an impulse or a reaction design ora combination of the two for the most efficient,cost-effective solution to plant productivity(Figure 3).

Configurations of the steam turbines consist ofthe following (Figure 4):

■ Condensing or non-condensing sets

■ Up, down, side and axial exhausts

■ Single or multiple internal extractionsand/or admissions

■ Uncontrolled extractions

■ Directly connected and gear-drivensteam turbines

Geared UnitsThe geared steam turbine-generator package

Marlborough,Massachusetts,

U.S.A.

Schenectady,New York,

U.S.A.

Bangor,Maine,U.S.A.

Florence,Italy

BusinessCenters

Sales & ApplicationSupport

DetailedEngineering

Manufacturing & Assembly Center

ServiceSupport World-Wide Locations


GE Power Systems ■ GER-3706D ■ (10/00) 1

Figure 1. The industrial steam turbine (IST) business

Figure 2. Global resources

Industrial Steam TurbinesJanuary 4, 1999

Nuovo PignoneSteam Turbines

GESchenectadySmall Steam

Turbines

ranges from 3 to 35 MW and may be the eco-nomical solution customers are looking for(Figure 5). The package consists of an efficient,

high-speed steam turbine driving a gearboxconnected to a four-pole, 50- or 60-Hz genera-tor. This compact package lends itself to quick



20-130 MW

3-35 MW

2-60 MW Up to 16,000 RPM

3-35 MW

Direct Drive ST-G

Geared ST-G

Feed Pump Drives

Mechanical Drive Units

0 5 MW 10 MW 15 MW 25 MW 35 MW 50 MW 75 MW 100 MW 150

Figure 3. Product line

Steam Turbine Generators• 3,000 to 130,000 KW, 50/60 Hz

• Applications– Cogeneration

– Small Power Production

– Combined Cycle

– Waste to Energy

– Geothermal Power Generation

• Configurations– Condensing/Non-Condensing

– Down, up and Axial Exhaust Configurations

– Single/Multiple Internal Extractions

– Uncontrolled Steam Extractions

– Direct Drive/Gear Driven

• Designs– Impulse

– Reaction

Figure 4. Product line configurations

installation. The turbine exhaust is adaptable toup or down orientations, and internal extrac-tion/admission valves can be added to thesteam turbine to suit a customer’s process steamneeds. Single-shaft steam turbine designs areavailable.

Mechanical Drive Steam TurbinesMechanical-drive steam turbines (Figure 6)range from 3 to 60 MW (80,000 BHP), withspeeds of up to 16,000 rpm, and are either con-densing or non-condensing types. Completesteam turbine compressor packages as well asseparate mechanical drive steam turbines,which meet API requirements, are available.Designs for a wide range of plant types and sizesare available. The IST team has extensive expe-rience in support for major compressor suppli-ers, engineering companies and other users.

GE’s test capabilities include:

■ Mechanical running tests

■ Full-train mechanical string tests

■ Rotor dynamic capability, includingresponse tests

Directly Connected ISTsISTs directly coupled to generators (Figure 7)range from 20 to 130 MW. The steam turbinescan be packaged with most of the auxiliaries toease plant design and installation problems.Axial exhausts can be used that allow a less cost-ly building design.

This line of turbines has many applications forthe use of extraction and admission processsteam, employing several combinations of inter-nal and external control valves. Using thesevalves provides GE’s customers with processflexibility and excellent partial-load efficiencywhen the turbine is used to supply processsteam.

Directly coupled steam turbines in combined-cycle applications must provide the perform-ance and flexibility required for integration



Geared Turbine Generator Sets

• Complete Packages CanInclude Turbine, Gear, OilSystem and Generator forQuick Installation

• Turbine Speeds Selected ToOptimize Life-cycle Costs

• 1500/1800 RPM, 4-PoleGenerators For 50/60 HzApplications

• Applications to ~35 MW

Geared Units; Offering a Cost-Effective Solution

Figure 5. Geared steam turbine generator sets

with gas turbines and heat-recovery boilers.Packaged arrangements, when feasible, offershorter delivery and installation time.

The directly connected ISTs can operate withfixed-inlet pressure or sliding-inlet pressurecontrol. They can be integrated with gas tur-bine and plant controls and they have auto- andremote-start capability.

Single-shaft steam turbine and gas (STAG)designs are available.

Feed Pump TurbinesFeed pump turbine drive packages are availablefrom 3 to 35 MW. Complete steam turbine boil-er feed pump packages are available, in addi-tion to stand-alone steam turbine packages.

The boiler feed pump turbine package uses:■ A microprocessor-based

electrohydraulic control system■ Modern instrumentation for remote

operation■ Dual-inlet capability for a wide range

of operation, from black-start toefficient main turbine extractionoperation

■ Flexible exhaust configurations (upand down)

■ Base-mounted packaged designs forease of installation and startup

Geothermal Steam Turbine Generator SetsGE offers highly reliable geothermal steamturbine generator sets (Figure 8). These steamturbines operate typically with saturatedsteam, which is provided from a geothermalsource. Their unique features and materials ofconstruction lead to long-term, reliable oper-ation in geothermal service. The followingfeatures have been incorporated into the geot-hermal design:

■ Inlet casings similar to those used onSTAG applications, which do not haveinternal inlet control valves



• MDT's, 2,500 HP to 80,000 HP• BFPT's, 3-35 MW• Single or double end drive• Inlet steam up to 1800 psig / 1000°F• (12 kg/cm2g/538°C)• Applications

– Utility Boiler / Reactor Feed Pumps

– LNG

– Ethylene / Methanol

– Urea / Ammonia

– Refineries

– Synfuel

– Process air

Figure 6. Mechanical drives

■ Special butterfly valves used forstartup, control and emergencyshutdown

■ Proven low-stress rotor designs and aspecial geothermal forging materialformula



• Quick delivery and installation

• Sliding or Fixed Pressure InletDesign

• Modernized Combined Stop &Control Valves

• Reheat Option Available

• Extractions / Admissions

• Advanced Steam Path Designs

• Proven Exhaust Sections for 50 &60 Hz

• Single-shaft Combine CycleDesigns Available

• Condenser Systems and OtherTurbine Island Scope Available

Figure 7. Direct coupled steam turbines

• Proven Low-Stress Rotor Designs & GEGeothermal Rotor Forging Material(NiCrMoV)

• 12-Cr Steam Path and HP Casing

• Carbon Steel Exhaust Casing with InconelInlay at Critical Surfaces

• 304L Stainless Steel Steam and Drain Piping

• Low cost Microprocessor - Based Electro -Hydraulic Control Systems - RS232 DCSlink

• Modern Hermetically Sealed LocalInstrumentation / Wiring For Reliable Long-Term Operation in a H2S GeothermalEnvironment.

• Up, Down, Side, and Axial ExhaustConfigurations Available

• Packaged, Base-Mounted Designs

Figure 8. Geothermal turbine

Technology Overview

Direct Coupled

Technology Overview

Geothermal Steam Turbine-Features

Reliable Equipment Backed by ST Engineering/Service

■ 12-chrome steel steam path and high-pressure casing

■ Carbon steel exhaust casing withinconel inlay at critical surfaces toprevent erosion

■ Stainless steel material for all steamand drain piping

■ Modern hermetically sealed localinstrumentation and wiring forreliable long-term operation in a H2Sgeothermal environment

■ Up, down, side and axial exhaustconfigurations available at 50 and 60 Hz

■ Packaged base-mounted designs

■ GE has extensive experience in thetechnology required for reliableoperation in geothermal steamapplications.

Modular Product StructureGE adopted a modular component structurefor its line of ISTs to achieve the cost and reli-ability benefits of standardization withoutcompromising turbine performance. Thisapproach enables the design engineer to opti-mize a turbine configuration for a customer’sspecific operating conditions by selecting andintegrating pre-engineered and field-provencomponents from an array of alternatives andthen designing a custom steam path that satis-fies an application’s unique requirements.Component modules that make up the build-ing blocks of the product line include bearingstandards (supports), inlet sections, inlet andextraction valve gear and exhaust sections.

These modules are shown for a typical indus-trial turbine in Figure 9 and Figure 10. Notethat the barrel section of the turbine is customdesigned for each unit based on the user’sspecific operating conditions. GE is able to

maximize reliability and performance whileminimizing product costs and delivery cyclesby using this flexible modular structure.Development efforts associated with this prod-uct line center on new, improved componentmodules to replace or augment existing ones.

Inlet Sections and CasingsInlet section construction is a function of inletpressure and temperature. A number of designsare available, as shown in Figure 11. For low-steam conditions, an economical, solid con-struction is employed where inlet ports are castas an integral part of the casing. For higher-steam conditions, either a free-expanding chestdesign employing an integral heat chamber ora nozzle box design with an inner casing isemployed. Both designs provide a high degreeof thermal flexibility for long casing life undercyclical conditions.

Valve GearThe type of valve gear used with the inlet sec-tions is also a function of the inlet flow for a par-ticular application. For low-flow applications, abar lift arrangement is used that reduces costand improves performance through reducedvalve-stem leakoff flow. For higher-flow applica-tions, a cam lift arrangement is used in which



A common thread

• Packaging

• Reliability

• Performance

• Flexibility

• Service

Designing Steam Turbines by usingBuilding Block Modules

Figure 9. Modular design philosophy

A Common Thread

each valve is individually supported and liftedfor high valve stability and long disc and seatlife. On applications with very high inlet flows,either a jumper valve is used to feed nozzles inthe turbine lower half, or an entire additionalset of valves is mounted in the lower half to pro-vide inlet flow control over a wide range ofoperations.

Downstream of the inlet section, the casing’sconical configuration allows a smooth and evenincrease in steam path area as the steamexpands toward the exhaust. The improvedconical casing designs, which utilize simple pat-tern pieces for each application, eliminate theuse of multiple cylindrical and transitional pat-tern sections and result in lower costs, reduced



Figure 10. Industrial turbine building block structure

Moderate inlet temperatures(solid construction)

High inlet temperatures(heat chamber construction)

High inlet temperatures(nozzle box with inner shell)

Figure 11. Alternative inlet concepts

Front StandardModule

Inlet Head& Valve Gear

Module

CustomBarrel

Section

CustomBarrel

Section

ControlledExtraction

Module

Exhaust HoodModule

Turbine Designed from Standard Modules with Customized Steampath

foundry cycles and reduced thermal stresses inthe casing.

New Inlet SectionA new inlet section module (building block)has been added to the IST structure. It can passa flow of 1,200,000 PPH at a bowl pressure of1800 psig and an inlet temperature of 1050°F.

Steam UtilizationToday, steam utilization is often as critical as aturbine-generator’s output. One of the featuresincorporated into our turbine designs is the useof internal extraction/admission (induction)valves. The use of internal valving allows opera-tion over a wide range of load and extractionflow conditions, where the turbine control sys-tem meters the through-flow to meet thedemands of the process headers.

GE has extensive experience in the supply ofsingle and double automatic extraction tur-bines into industrial processes. Flexibility ofoperation is further enhanced through the useof GE controls, which are described later. Theuse of internal control valves also simplifiesplant design and construction by eliminatingthe need for multiple casing openings and com-

plex valving. However, this is secondary to thecapability of efficient operation in a wide rangeof inlet and extraction/admission flows.

Non-Condensing TurbinesNon-Condensing turbines are used in manypaper mills and desalination plants (Figure 12).These turbines act as pressure reducing stationsand at the same time provide reliable power forthese plants. Again, a matrix of components isavailable for a wide range of exhaust flows inboth up and down configurations.

Other applications of industrial and cogenera-tion turbines include geothermal and districtheating installations.

District HeatingDistrict heating turbines are designed for verylarge extraction flows at low pressures (for win-ter operation). Modern designs have beendeveloped for this application with internal valv-ing using a grid valve to position the movablevalve disc.

Improvements in Performance Improvements in IST performance have beenachieved by combining design features previ-



Figure 12. Turbine configurations

Straight Non-CondensingHigh Flow Non-Condensing

ously proven on utility units, where the eco-nomic implications of performance are tremen-dous, with other line-specific enhancements.

These enhancements largely have been madepossible by the latest computer-aided designtools, which enable the turbine designer toimprove turbine performance without compro-mising reliability. Through the use of thesetools, the aerodynamic performance, stress dis-tributions and rotor dynamics associated with aparticular turbine configuration can be estimat-ed more accurately and optimized. As a result,more compact steam path configurations withreduced leakage, profile and secondary flowlosses become a reality.

Further improvements in performance havebeen achieved by the increased application ofefficiency-enhancing components, includinground-skirted buckets in the shorter stages,locking buckets in lieu of notch blocks at thepoint of bucket insertion, conical sidewalldiaphragms and slant-tip buckets with root andtip spill strips.

Special attention has been paid to optimizingthe performance of low-pressure turbine sec-tions, where the latest three-dimensional designtools have been employed to improve the aero-dynamic performance of buckets, nozzles andexhaust hoods. As an example, the low-pressuresection utilizing the 20-inch/508-millimeterlast-stage bucket (Figure 13) shows a perform-ance improvement of 1.5 to 2%, over the previ-ously used design.

The last-stage bucket’s design enhancementsinclude the following:

■ Continuously coupled tip constructionutilizing the well-proven over/undercover concept for improved dampingand modal suppression

■ Loose tie wires relocated to a lower

velocity region for improvedperformance and increased structuraldamping

■ Improved dovetail design permittingoptimized bucket root flow passagegeometry

■ Improved vane design, optimized forcentrifugal untwist and radial flowdistribution, to minimize aerodynamiclosses

■ Transonic convergent-divergent flowpassage at the tip section to minimizeshock losses

■ Self-shielding bucket material and L-shaped cover with integral sealingrib for improved erosion protection

For the largest industrial turbines, a nonreheat,low-pressure section, utilizing a 30-inch/762-millmeter last-stage bucket, in a single-flowconfiguration, has been developed for outputsup to 130 MW, in a single casing, with minimalexhaust loss. The 30-inch/762 millimeter last-stage bucket has been in service on utility unitsfor over 25 years and has an excellent operat-ing history.



Figure 13. 20-inch (508 mm) last-stage bucket

BearingsThe reliability and dependability of steam tur-bines depend on rotor dynamics and bearingperformance (Figure 14). Tilting pad journaland thrust bearings are now used on the vastmajority of IST applications. These bearingsprovide optimal rotor stability and ensure ahigh degree of reliability due to their toleranceof misalignment. Proper selection of these criti-cal components is part of our design process.

For each turbine application, an in-depth later-al and torsional rotor dynamic analysis is per-formed following the development of a prelim-inary design. Consideration is given to everypossible destabilizing force, such as those frompartial arc diaphragms, inlet valves and extrac-tion controls, to ensure that the componentmodules selected for each application will resultin a turbine unsurpassed in reliability.

The steam path is the very essence of a turbineand its design essentially determines the tur-bine’s performance.

FrequencyIn many developing countries around theworld, the utility, or site grid, often operateswithin a wide range of frequency. Steam turbineoperation in such a situation can cause vibrato-ry stress problems. When operation in a widefrequency range is expected, the turbine can bedesigned using tools developed for mechanicaldrive steam turbines, where operation at ornear a natural frequency of a component is ana-lyzed to ensure long component life.

Axial ExhaustsIn the past, most steam turbines that weredesigned for industrial and cogeneration appli-cations have featured a down exhaust arrange-ment with an underslung condenser. However,exhaust losses, as well as turbine building costscan be reduced through the use of an axialexhaust arrangement with an in-line condenser.

Most GE ISTs are now available in an up, downor axial exhaust configuration. The axial



Figure 14. Turbine bearings

exhausts (Figure 15) have been designed withperformance in mind and incorporate aerody-namically efficient bracings and optimized cas-ing wall geometrics. On average, the selectionof an axial exhaust arrangement can improveturbine performance by 0.25 to 0.50%. For a 40MW turbine, that can mean an additional 100to 200 KW for the same amount of fuel. Theplant arrangement benefits of the axial exhaustconfiguration are discussed in greater detaillater.

Turning GearOptional turning gear packages (Figure 16) arecomposed of an electric motor that drives a sin-gle-, double- or helical/worm reduction gearreducer through a torsionally resilient cou-pling. The input half of a syncro-self-shifting(SSS) overrunning clutch is mounted to theoutput shaft of the gear reducer, with the out-put half mounted to the turbine rotor. Theclutch operates automatically, by mechanicalmeans, to engage whenever the input speed(turning gear) is the same as or greater than theoutput speed (i.e., turbine speed). Therefore,when the turning gear motor is energized, the

clutch will engage only if the driven equipmentis stationary or turning at a speed equal to theturning gear speed. This leads to one of thegreatest operational characteristics of the sys-tem, the ability to catch on the fly. If the turninggear controls are configured to start the motorwhile the steam turbine is coasting down, it willautomatically engage when the input and out-put clutch speeds are synchronous, thus avoid-ing the need for a zero speed signal (from therotor at rest). This is by far the most advanta-geous means of operating the turning gear,offering the best protection to the rotatingrotor while minimizing the duty cycle on theturning gear. In its simplest form, in order for itto operate, this turning gear package requiresthat motor power and lubricating oil be takenoff the bearing supply header.

The design method and rules we follow serve toprotect the turning gear from damage. If theturning gear experiences a load in excess of itsdesign, the motor simply will trip out on over-load and the turning gear components will notfail. The unit will only produce a certainamount of torque, and the components aredesigned to handle this load with appropriateservice factors. In fact, this turning gear can beused as an excellent indicator of train integrityproblems. If there is train misalignment, tip orseal rubs, the turning gear motor will drawgreater amperage after breakaway as an indica-tor of the increase in load.

SPEEDTRONIC™ Mark VI ControlGE ISTs are available with the SPEEDTRON-IC™ Mark VI Control, the latest generation ofour steam turbine control product line. Thisturbine control system is available in either sin-gle-channel or triple-redundant configurationsand offers a number of enhancements over pre-vious generations of turbine control.



Figure 15. Axial exhaust configuration

The SPEEDTRONIC™ Mark VI turbine controlis the current state-of-the-art control for GE tur-bines. It is based on over 30 years of successfuloperation of electronic turbine control systems.It is designed as a completely integrated con-trol, protection and monitoring system for gen-erator and mechanical drive applications forgas and steam turbines. It is also an ideal plat-form for integrating all power island and bal-ance-of-plant controls.

RedundancyMark VI control systems are available in simplexand triple redundant forms for small applica-tions and large integrated systems, with controlcapability ranging from a single module tomany distributed modules. The name triplemodule redundant (TMR) is derived from thebasic architecture of three completely separateand independent control modules, power sup-plies, and IO Nets. Mark VI is the third genera-tion of triple-redundant control systems thatwere pioneered by GE in 1983.

Sensor interface for TMR controls can be single,

dual or triple redundant, or combinations ofredundancy levels. The TMR architecture allowsuninterrupted operation following a single-point failure in the electronics and repair of thedefective card or module while the process isrunning. Adding sensor redundancy increasesan overall system’s fault tolerance.

Another feature of the TMR is its ability to dis-tinguish between field sensor faults and internalelectronic faults. Diagnostics continuously mon-itor the three sets of input electronic and alarmany discrepancies between them as an internalfault versus a sensor fault. In addition, all threemain processors continue to execute the cor-rect two out of three “voted” input data.

Mark VI TMR Control Configuration

Operator InterfaceThe operator interface is commonly referred toas the human-machine interface (HMI). It is aPC with a Microsoft® Windows NT® operatingsystem supporting client/server capability, aCIMPLICITY® graphics display system, a con-trol system toolbox for maintenance and a soft-ware interface for the Mark VI as well as othercontrol systems on the network. The HMI canbe applied as:

■ The primary operator interface forone or multiple units

■ A backup operator interface to theplant DCS operator interface

■ A gateway for communication links toother control systems

■ A permanent or temporarymaintenance station

■ An engineer’s workstation.

HMI System StructureThe HMI system can provide plant visualization



Figure 16. Turning gear

for control systems that span a wide range ofequipment. Systems using the Mark V HMI mayinclude one or more of the following types ofequipment:

■ Mark V gas or steam turbine control

■ Mark VI gas or steam turbine control

■ EX2000 generator voltage regulator

■ Generator protection

■ LCI static starters

■ Historians

■ Engineering workstations for systemtools

■ System and documentation printers

■ Ethernet networking components

■ Arcnet networking components

■ Integrated third-party systems

■ HRSG controllers

■ Balance-of-plant controllers

■ GE integrated control system

CommunicationsCommunications are provided for internal datatransfer within a single Mark VI control or com-munications between Mark VI controls andpeer GE control systems as well as external com-munications to remote systems such as a plant-distributed control system (DCS). The unit datahighway (UDH) is an Ethernet-based local areanetwork (LAN) with peer-to-peer communica-tion among Mark VI controls, EX2000 genera-tor excitation controls, static starters, the GEFanuc family of PLC-based controls, HMIs andhistorians (Figures 17–19).

VF Series Fluid System PackageThe VF series fluid system packages combineGE’s experience from the industrial, petro-chemical and power industries into a robust,full-featured, highly reliable and low-mainte-nance product offering that is optimized to ful-fill the demanding requirements of today’scompetitive power generation marketplace.



VCMI UCV_ VTURVAICVSVO VVIB VGENVTCCVRTDVCRC

GovernorOperator / MaintenanceStation

RS232/485 Modbus Slave RTU/ASCII

RS232/485 Modbus Slave/Master RTUEthernet TCP-IP Modbus SlaveEthernet TCP-IP GSMCIMPLICITYR Drivers

Communication Links to Plant DCS

Ethernet

Flat Panel &Touchscreen

Genius Bus

Remote I/O

Gen

Actuator

Actuator

Inlet Pressure

Trip

Speed

Extraction Pressure

Exhaust Pressure

Shaft Voltage & Current Monitor

Automatic Synchronizing

OR

(20)

Ana

log

In &

(4)

Out

(4)

Ser

vos

Spe

ed, A

uto

Syn

ch,

SV

M, T

rip

(48)

Con

tact

In &

(24

) O

ut

Pro

xim

itors

: (1

6) V

ibra

tion,

(8)

Pos

ition

, (2

) K

P

(16)

RT

Ds

(24)

The

rmoc

oupl

es

(2)

3 P

hase

PT

s &

(3)

1 P

hase

CT

s

Vibration, Thrust, Differ, Expan, Eccentricity

Temperature (RTDs)

Temperature (Thermocouples)

Generator 3 Phase PTs & 1 Phase CTs

CIMPLICITY Drivers®

Figure 17. Industrial steam turbine control – architecture



Figure 18. The Mark VI

Steam TurbineControl Cabinet

• NEMA 1 Convection Cooled

• Front Access

• Top/Bottom Cable Entrance

• Separate High & Low LevelChannels

• Various Cabinet ArrangementsAvailable

C C

Figure 19. The Mark VI

Control Cabinet

The VF package includes a hydraulically sepa-rate lubrication and lubricating oil dehydrationsystem, a hydraulic fluid supply and condition-ing system and a common control console in asingle package (Figure 20). The fluid systempackage can mount separately from the steamturbine-generator or be installed integrally withthe turbine base.

Full-Feature Designs■ Redundant ac motor-driven pumps for

both lubrication and hydraulic service

■ Duplex lubricating oil filters and oilcoolers

■ DC motor-driven emergency oil pump

■ Integral lubricating oil dehydrationsystem

■ Lubricating oil mist elimination system

■ Redundant hydraulic filters

■ Integral hydraulic fluid conditioning

and cooling system

■ Oil pressure and temperature controls

■ Extensive instrumentation

■ Enclosed control console with integralgauge board

■ Stainless steel pipe and epoxy finishcoatings

Simple, Cost-Effective Installation■ A single package requiring a single

foundation for the fluid system

■ Compact size to ease the plantarrangement

■ Suitable for four-point support orperimeter grout

■ Factory performance test to verifyperformance

■ Stainless steel pipe and factory cleaningto reduce the installation cycle



Figure 20. GE VF fluid system

Operational Reliability■ Manufactured to fully detailed GE-

produced drawings, for control andrepeatability

■ Simple, robust construction

■ Redundant components for onlinemaintenance

■ Online testability

■ Sealed reservoir and console

■ Integral continuous fluidconditioning

■ Two of three voting trip solenoids(electrical trip device) for faulttolerance

■ Special-purpose dc motor designs forpredictable and reliable performance

Performance and Economy■ Proven fluid-system components

shared with other VF designs andrefined by continuous improvement

■ Custom selection for each site toassure performance and suitability forsite conditions

■ Extensive use of specialized integratedhydraulic circuits for simple assemblyand leak-free construction

■ Watertight construction to resistmoisture contamination of fluids ordamage to controls

■ Integral oil-side temperature control

■ Dehydration system circulating pumpand heaters, which double as startupheaters

■ High-performance filtration, for totalfluid cleanliness

■ Stainless hydraulic reservoir andstainless pipe throughout

■ Lightweight hydraulically efficientreservoir construction for strength

■ Epoxy-finish coatings

■ Extensive control interfaces with GE’scontrol system and the plant DCS

■ Motors suitable for 50°C ambientconditions

Simple, Cost-Effective Maintenance■ Extra-severe-duty motors for extended

operating life and power margin

■ C-face motors with rabbet fits for easyalignment with high-tolerance,oversize couplings

■ Long-service life, high-capacity filterelements

■ Spin-on desiccant canister to preventmoisture from contaminating thehydraulic fluid

■ Hydraulic fluid conditioning and largehydraulic reservoir that reduce stresson the operating fluid and extendfluid service life

■ High-performance dehydration systemeliminates free-water contaminationand prevents lube oil deterioration.

Environmental Compatibility■ High-efficiency centrifugal pumps and

variable-capacity hydraulic pumps tominimize power consumption

■ Oil-mist elimination system to reduceoil discharges

■ Integral dehydration system with noexternal piping or connections to thesewer to eliminate another potentialsource of oil discharge

■ Long fluid service to reduce spentfluid disposal costs



■ High-performance, high-capacityfiltration to reduce element disposalcosts

Ability to Meet Site Conditions■ Customized for a specific site

environment

■ Optional materials for aggressiveatmospheric and cooling waterenvironments

■ Large inventory of practical solutionsfor unique site problems

■ Optional control configurations forthe plant DCS or GE turbine controlsystem

■ Available local pump and motorcontrol panels

■ Highly experienced GE systemengineering for fluid, innovativesolutions to difficult problems

Application RangeThe VF-F/Q design series includes sizes forapplications with steam turbines and combined-cycle steam turbines with either air-cooled orhydrogen-cooled generators and system flowcapacity from 70 up to 900 gallons per minute(nominally 10–350 MW).

The VF-HP series, VF-LP series, UT series andTCS series are designs available for industrialpower, vintage machine replacement, mechani-cal drive and control retrofit applications.

Turbine Factory PackagingGE has been the pioneer in the area of “pack-aged” industrial steam turbine-generators,which are completely assembled and aligned inthe quality-controlled environment of the facto-ry. The units can be mounted on bases for quickand easy installation and alignment verificationin the field. Piping, wiring and testing are also

performed in the factory to the maximumextent possible. The benefits of factory packag-ing are minimized installation time and cost,with reduced risk to the schedule. To date, GEhas shipped more than 120 packaged steam tur-bine-generators representing more than 4.5gigawatts in output capacity.

The experience gained in packaging thesesmaller units has now been applied to largerunits. Specifically, GE now offers packagedsteam turbine-generators using up to a 23-inch/584.2 millimeter last-stage bucket in downexhaust configurations and a 30-inch/762 mil-limeter last-stage bucket in axial exhaust config-urations. This means that units of up to 80 MWwith a down exhaust and 130 MW with an axialexhaust can be shipped to site, fully assembledand base mounted, with virtually all unit pipingand wiring done in the factory.

Features of the Packaged TurbineDue primarily to shipping limits, the turbine-generator and lubrication and hydraulic sys-tems are provided on separate prepackagedbases or skids. With nonaxial exhaust turbinesthe lubrication and hydraulic oil system can beinstalled into the turbine base.

Steam turbines come factory aligned on a basefabricated from I-beams. Optical targets areprovided at each corner of the base, and their(vertical) locations relative to a common refer-ence are recorded following factory alignment.Once the unit is on site, the base is leveled usingbase jacking bolts to duplicate the factory set-tings.

To provide an additional field alignment check,a pin is fitted at the factory in the gib key thatguides the high-pressure shell at the front stan-dard. If the pin can be easily inserted andremoved after the base is leveled in the field,then no twists and strains have been put into



the base during field installation and the upper-half casing need not be removed to confirm thealignment.

On units supplied with a spray chamber in lieuof a gland condenser, the entire steam seal sys-tem can be fabricated and assembled in the fac-tory prior to shipment, thus saving considerabletime and installation cost in the field.

On other units, because of its size, the skid-mounted gland condenser system is installedseparately beside or below the turbine. Allsteam seal piping is factory assembled, and aflanged connection is provided at the edge ofthe base for field interconnection to the glandcondenser.

A low-profile combined lubrication andhydraulic system can be provided for mountingin close proximity to the turbine-generator. Thesystem design and the short distance betweenthe turbine-generator and the lubrication andhydraulic system minimize the vertical droprequired for proper oil drainage and allow axialexhaust turbine-generators to be mounted at orclose to grade for lower building and installa-tion cost.

Feed and drain piping are assembled in the fac-tory and are terminated at a single point at theedge of the turbine base. Only a short length ofprefabricated interconnecting piping, withflanged connections and flexible expansionjoints needs to be installed in the field.Installation and flushing time in the field isminimized because the feed and drain piping ismounted on the turbine base, and the com-bined lubrication and hydraulic skid are pre-cleaned in the factory.

All turbine-generator electrical devices and sen-sors are prewired in the factory with connec-tions terminated in junction boxes located onthe bases.

Figure 21 shows a typical 80 MW automatic-extraction condensing steam turbine without abase, mounted on a traditional pedestal. Theunit’s exhaust is directed downward into anunderslung condenser.

Foundation complexity, as well as installationtime and cost, can be reduced by selecting abase-mounted down exhaust unit with an on-skid lubrication and hydraulic oil system, asshown in Figure 22.

Axial ExhaustCosts can be further reduced by selection of anaxial exhaust configuration. Figure 23 shows anaxial exhaust turbine of the same capacity andsimilar functionality that is base mounted in alow-profile configuration.

The following describe the advantages of thepackaged axial-exhaust, low-profile design overthe unpackaged down exhaust design.

Improved Turbine PerformanceThe performance of an axial exhaust unit is typ-ically 0.25 to 0.50% better than a comparabledown exhaust unit. The present value of thefuel savings over the operating life of the unitcan range from 2.5 to 12.5% of equipment cost.

Reduced Building CostsThe overall height of the building can be low-ered significantly by the low-profile design. Thetotal amount of concrete required and the com-plexity of the foundation design are reducedsignificantly.

Reduced Installation Costs The packaged design includes pre-assembledand precleaned piping as well as all unit electri-cal and instrumentation wiring that is terminat-ed in junction boxes for reduced field installa-tion time. Additionally, the time required toinstall the axial condenser and check the align-





Figure 21. Unpackaged down exhaust unit in pedestal installation

Figure 22. Packaged down exhaust unit in a pedestal installation

ment of the turbine stationary and rotatingparts is reduced.

Reduced Installation TimeExperience has demonstrated that a packagedturbine-generator can be installed in up to 40%less time that an unpackaged unit. Withreduced potential for field installation delays,plants can be brought on line faster than everthought possible.

Cost ComparisonA cost comparison between the alternativesshown in Figure 21 and Figure 23 are shown inFigure 24.

Approximately a half million dollars (U.S.) intotal cost is saved by selecting the packaged tur-bine-generator with an axial exhaust in a low-profile installation. It should be noted thatthese savings do not include any fuel cost sav-ings or savings associated with a faster plantstartup. These savings vary from application toapplication but can be quite significant formany independent power projects.

It should also be noted that although the eco-nomic advantages of selecting a base-mountedaxial exhaust design are considerable com-pared to a comparable unpackaged GE designwith a down exhaust, they are even larger incomparison to the multicasing designs offered

by other manufacturers. These designs incorpo-rate separate high-pressure and low-pressureturbines interconnected by a cross-under pipe.The turbine-generator unit arrives on site in sev-eral more pieces than a GE single-casing unit;utilizes a higher and more elaborate founda-tion; and requires significantly more time onsite for field piping, wiring and alignment.

Design Standardization

Increased Design StandardizationGE has optimized the standard components uti-lized in its building-block structure, to reducethe number of “special” and infrequently usedmodules. Greater use of optimized and fre-quently applied component modules results inreduced design, drafting, sourcing and manu-facturing times.

Increased Design AutomationAn automated design system has been devel-oped to optimize turbines for specific applica-tions by selecting and combining standard com-ponent modules. The system automatically laysout the turbine steam path from which manyturbine component detail drawings can bedownloaded and created electronically, with anabsolute minimum of drafting time.

While the turbine design is automated and



Figure 23. Packaged axial exhaust unit in a low-profile installation

developed from standardized hardware mod-ules, a full mechanical analysis is done to checksteady-state and vibratory stresses on themachine. This design process results in a steamturbine configuration with maximum powerdensity that has been fully analyzed in its cus-tom configuration. The level of design automa-tion employed enables the development of first-level casting and forging drawings within a fewweeks following receipt of an order.

Sourcing PartnershipsGE has developed partnerships with major sup-pliers of long-lead and high-value turbine com-ponents. Extensive producibility reviews havebeen held with these suppliers to make sure ourdesigns can be executed by them in minimaltime while still ensuring high quality. Thesereviews have led to several changes in the designof head castings for reduced cycles, such as the

use of customized conical barrel-section pat-terns. To reduce rotor-forging cycles, GE hasreserved a number of slots in our major forgingvendors’ production plans to ensure customrotor forging availability in the minimum possi-ble cycle time.

Additionally, our automated production plan-ning system with it electronic data interchangecommunications, allow automatic placement ofmany component orders with suppliers imme-diately following the release of a design formanufacture. As many as half of all purchaseorders placed by GE are now executed directlythrough the system with minimum buyer inter-vention.

Manufacturing InitiativesIncreased use of numerically controlledmachine tools has led to a reduction in manu-facturing cycles for casings, rotors and steam



Figure 24. Savings from a 40 MW base-mounted turbine with an axial exhaust and low-profile plant layout

Savings From Low Profile Base MountedAxial Exhaust Steam Turbine

Plant CostSavings

Installation Savings

Total Savings

Savings ($K)0 100 200 300 400 500 600

$$

$$

$$

path components. Major subassemblies, such asthe front standard, the valve gear and the oil sys-tem, can be fully assembled and tested beforefinal unit assembly. This parallel manufacturingapproach results in shorter total cycle times.

Increased Packaging Increased assembly and packaging of steam tur-bines in the factory allows significant reductionin the time from site delivery to synchroniza-tion. Less work done on the site also minimizesthe risk of unforeseen installation problems,which can extend project schedules.

Project Execution Every order is executed by a project team head-ed by a project manager. This single-point con-tact coordinates all technical communication toand from the customer and acts as the focalpoint for internal coordination. Proper com-munication and project support from theseexperts is critical to the timely completion ofthe turbine-generator set as well as its integra-tion into a customer’s site.

ConclusionMany innovations have been developed andadopted in the IST product line, to better meetthe needs of industrial users. While improvingupon the previous generation of turbines, basicproduct line attributes have been retained.

These well-known and proven features havemade GE a leader in the areas of performance,reliability, dependability, maintainability andlife-cycle costs. Enhancements to the productline further build on these strengths withoutcompromising one for the other. As a matter ofpolicy, GE attempts to develop product lineimprovements that not only are applicable tothe new units it builds but also can be retrofit-ted into the large and ever-expanding fleet ofindustrial units already operating in plantsaround the world. Through this approach,users of older GE turbines are able to benefitfrom newly developed enhancements in theproduct line.

Our experience suggests that power producers,particularly those employing gas turbines as theprimary heat source for the steam turbine,require faster delivery cycles than were requiredin the past. GE has taken steps to reduce itscycle times for its industrial steam turbine-gen-erators to respond to this need. A combinationof integration as well as design, manufacturingand sourcing initiatives has made these reduc-tions possible.

GE’s IST business unit has a broad product line,can offer shorter delivery cycles on its products(as short as 12 months or even less) and pro-vides responsive quotes at competitive prices(budgetary quotes within 48 hours).



List of Figures1. The industrial steam turbine (IST) business

2. Global resources

3. Product line

4. Product line configurations

5. Geared steam turbine generator sets

6. Mechanical drives

7. Direct coupled steam turbines

8. Geothermal turbine

9. Modular design philosophy

10. Industrial turbine building block structure

11. Alternative inlet concepts

12. Turbine configurations

13. 20-inch (508 mm) last-stage bucket

14. Turbine bearings

15. Axial exhaust configuration

16. Turning gear

17. Industrial steam turbine control – architecture

18. The Mark VI

19. The Mark VI

20. GE VF fluid system

21. Unpackaged down exhaust unit in pedestal installation

22. Packaged down exhaust unit in a pedestal installation

23. Packaged axial exhaust unit in a low-profile installation

24. Savings from a 40 MW base-mounted turbine with an axial exhaust and low-profile plant layout



For further information, contact your GE Field SalesRepresentative or write to GE Power Systems Marketing

GER 3706D, 10/00 (2.5M)

gGE Power Systems

GE Power Systems4200 Wildwood ParkwayAtlanta, GA 30339

ger-3706d - steam turbines for industrial applications

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