Answers for energy.

Advanced Compressor Cleaning System for Siemens Gas Turbines

Presented originally at:POWER-GEN Asia 2010 – Marina Bay Sands Resort, SingaporeNovember 2–4, 2010

Author:Dipl.-Ing. Marcus Gera, Siemens AG,Energy Sector, Energy Service Division

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Content

Abstract 4

Tasks 4

Scope of supply 5

Off-line nozzle system 6

On-line nozzle system 6

Wash skid 7

Performance of ACCSpro Compressor Cleaning 8

Optional Compressor Wash Prediction (COWAP) analyzer module 9

Customer benefits 10

References 11

Conclusion 11

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Low compressor fouling while using ACCSpro

Abstract Tasks

The Advanced Compressor Cleaning System is used to remove deposits which have formed on airfoils and caused a de-cline in output and efficiency. Provision is made for removing such deposits by performing the cleaning operation either on-line (at rated speed) or off-line (in conjunction with the startup equipment). On-line cleaning is primarily intended for preventing the accumulation of a layer of soiling. For this reason, it is recommended that after commencement of commercial operation the compressor initially be cleaned once a day with demineralized water and every third day with a corre-sponding cleaning agent. Off-line wash-ing with a corresponding cleaning agent is performed at reduced speed and has a more pronounced cleaning effect. De-pending on the type of soiling, repeated cleaning operations may be necessary to achieve a further improvement in output and efficiency. If operating conditions per-mit, off-line cleaning should be performed once a month or at a suitable opportunity (if a scheduled or unscheduled shut down allows for it). The cleaning intervals given here are intended as guideline values. Depending on the operating mode of the gas turbine, pollutants contained in the intake air, and the type of deposits, opti-mum cleaning intervals may differ from those stated in this document. Insights gained during the course of plant opera-tion will enable the operator to determine whether this interval can be further opti-mized by considering all relevant factors.

Siemens Energy answers the permanently increasing market requirements for com-bined cycle power plants such as high performance, low emissions, operational flexibility, and life cycle cost with contin-uous research and development process. Especially the gas turbine as the core component of a combined cycle power plant is affected by these requirements.

To help you improve the performance of your gas turbine and your operating plant competitiveness Siemens Energy Service offers many innovative solutions. One of these is the Advanced Compressor Cleaning System pro upgrade (ACCSpro).

Many power plant operators have long since resigned themselves to losing power because of dirty compressor blades. They think it is unavoidable. Even the best air filters still allow lots of micro particles and some dirt, moisture and, in particular, CHx compounds, salts and aerosols to pass through with little hindrance. CHx compounds not only cling to the blades, but also help dirt and grime adhere to them much more strongly.

The consequences include rougher sur-faces, higher turbulence levels, deterio-rating flow patterns, reduced cross section of flow, higher compressor outlet temper-atures and lower compressor outlet pres-sures. All this can quickly add up to 4% loss of power. For a 150 MW gas turbine compressor, that means 6 MW less output and corresponding loss of power sale earnings.

The ACCSpro system sustainably minimizes the fouling of the compressor blades and vanes, and was especially designed for the Siemens heavy duty gas turbine fleet. While the cleaning effect of most non-OEM cleaning systems lasts but a few days, our spraying systems, cleaning solutions and a well-balanced combination of washing procedures reduces lastingly new fouling. Lowest water consumption along with optimized cleaning effects ensures a per-manent power gain and a short payback time. For the SGT5-4000F (V94.3A) fleet a Compressor Wash Prediction (COWAP) analyzer module optimizes the best use of the system.

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CFD analysis

Scope of supply

The Advanced Compressor Cleaning System pro (ACCSpro) from Siemens Energy is just one of the many innovative modernization packages available.

The scope of this upgrade includes:

Computational Fluid Dynamics (CFD) ■

optimized droplet number and size for less erosion and better cleaning effect (OEM developed system)

Frame-specific nozzle arrangement ■

(On- and off-line system)

On- and off-line washing sequences ■

Lowest water, detergent, and antifreeze ■

rinsing fluid consumption

Automatic skid with optional ■

interconnection to the instrumentation and control system

Interconnect piping from the skid ■

to both nozzle systems

Siemens Energy recommend that the installation of this upgrade be performed at a major inspection. The skid and the interconnect piping installation can be done before the outage. Siemens Energy offers a full range of field service capabili-ties to help you manage your maintenance and outage schedules.

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Inner cone distribution ring system

On-line nozzle system

Off-line nozzle system

Off-line cleaning with an appropriate cleaner will result in more intensive cleaning at crank speeds. Depending on the kind of fouling, the cleaning cycle can be repeated to improve the cleaning effect with the aim to achieve a further increase in output and efficiency. If practicable under the existing operating conditions, off-line cleaning should be performed once per month or on appropriate occasions (but at least 4 to 6 times per year).

The off-line nozzle system comprises the nozzles that are mounted on the inner cone upstream of the spider that supports the compressor bearing in the casing. The spray nozzles in the off-line nozzle system generate a water spray, which covers the full airfoil height. Off-line nozzles are connected to a distribution ring line mounted in the inner cone.

On-line cleaning is essentially intended to avoid the build-up of a layer of dirt. For this reason, the first measures to be implemented after the start of commercial operation should include daily washing of the compressor with fully demineralized water. As the unit accumulates more operating hours, the owner will have to decide whether an optimum cleaning interval can be achieved by taking into account all possible influences.

The on-line nozzle system comprises nozzles that are mounted on the inner cone upstream of the spider which supports the compressor bearing in the casing. The hollow cone spray nozzles in the on-line nozzle system generate a water spray that covers the full airfoil height. On-line nozzles are connected to a distribution ring line mounted in the inner cone.

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Wash skid

ACCSpro wash skid

ACCSpro system overview (application example for two gas turbines)

Off-line wash sequence

The water tank is loaded by a permanent supply connection. Filling the water tank with demineralized water is performed automatically using a solenoid valve.

Detergent is filled into the mixing tank. The detergent filling process is done by the means of an electrically driven drum pump which is part of the wash skid hardware. The permanent demineralized water connection allows for supplying the mixing tank with demineralized water. Optionally, transport containers for clean-ing agent and antifreeze can be mounted above the demineralized water and mixing tank.

A centrifugal pump is provided on the one hand to prepare a homogeneous mixture of demineralized water and cleaning agent and antifreeze rinsing fluid in the mixing tank, by using a solenoid valve and to prepare a homogeneous mixture of demineralized water and anti-freeze rinsing fluid in the water tank via another solenoid valve. On the other hand, this pump forwards the cleaning fluid through the solenoid valves at the skid output connections and then to the both nozzle systems.

With one common skid a maximum of four gas turbines can be supplied.

Ambient temperature operation limits:

Operation limits without antifreeze rinsing fluid: + 8°C (on-line), + 5°C (off-line)

Operation limit with antifreeze rinsing fluid: – 10°C

Skid and I/C-piping Nozzle System

GT1

GT2

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Performance of ACCSpro Compressor Cleaning

Compressor efficiency increase after washing events

Offline GT Shut Down ETAVPumre – Part 2 ETAVPumre – Part 4 ETAVPumre – Part 6 ETAVPumre – Part 8 ETAVPumre – Part 10 Linear (ETAVPumre – Part 1) Linear (ETAVPumre – Part 3) Linear (ETAVPumre – Part 5) Linear (ETAVPumre – Part 8) Linear (ETAVPumre – Part 10)

Online ETAVPumre – Part 1 ETAVPumre – Part 3 ETAVPumre – Part 5 ETAVPumre – Part 7 ETAVPumre – Part 9 Linear (ETAVPumre – Part 7) Linear (ETAVPumre – Part 2) Linear (ETAVPumre – Part 4) Linear (ETAVPumre – Part 6) Linear (ETAVPumre – Part 9)

∆=0.22%∆=0.22%∆=0.22%

∆=0.24%

∆=0.22%

∆=0.44%

Offline w/CLOSED IGV

Overview

Date

Poly

tro

pic

co

mp

ress

or

eff

icie

ncy

in

%

13.03.0905.06.0925.02.0917.11.0809.08.0801.05.08

90.2

90.3

90.4

90.5

90.6

90.7

90.8

90.9

91.0

The consequence of dirty compressor blades include rougher surfaces, higher turbulence levels, deteriorating flow patterns, reduced cross section of flow, higher compressor outlet temperatures, and lower compressor outlet pressures, thus lower compressor efficiency.

A frequent compressor cleaning has two positive effects on the compressor efficiency:

Recover the reversible part of the ■

compressor fouling

Postpone the irreversible compressor ■

fouling to a later date

The following graph shows the significant effect of washing events with ACCSpro on the compressor efficiency:

The increase in compressor efficiency has a positive impact on the performance of the gas turbine as well as on the combined-cycle (CC) performance, since it is directly proportional to the gas turbine (GT) power, GT efficiency, CC power and CC efficiency.

The following values show the impact of 1%-point polytropic compressor efficiency for a SGT5-4000F (V94.3A) gas turbine*:

~ 1.64% GT power ■

~ 1.1% CC power ■

~ 0.96% GT efficiency ■

~ 0.42% CC efficiency ■

* expected values (not guaranteed)

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Optional Compressor Wash Prediction (COWAP) analyzer module

Prediction of performance recovery by compressor off-line cleaning

It is recommended to install the Compressor Wash Prediction (COWAP) analyzer module for ACCSpro as a part of the Thermodynamic Diagnostic Module (TDM) on Instrumentation & Control -system (I&C). It allows for a prediction of performance recovery by compressor off-line washing, which implies the determining of the optimal timing for the off-line washing.

Furthermore, there are modules for:

an overall thermodynamic gas turbine ■

observation

a prediction of performance recovery ■

by inlet filter exchange

a trend monitoring of compressor ■

efficiency.

How much performance can be actually gained by:■ changing from part to base load■ off-line cleaning of the compressor

100 10098.9 99.2

96.3

97.7

86.4

96.4

EfficiencyPower output

Perf

orm

ance

par

amet

er,

re

lati

ve [

%]

100

95

90

85

80

Reference level Potential base load performance after compressor off-line cleaning Potential base load performance Actual performance

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Customer benefits

On-line wash sequence

The Advanced Compressor Cleaning System pro upgrade (ACCSpro) can be a cost-effective means to help you to improve the overall performance of your gas turbine plant.

Benefits may include:

Avoidance of power loss up to 4% ■

of maximum performance

Avoidance efficiency loss due ■

to reduced compressor fouling

Fuel saving through keeping the ■

specific heat rate

Increased availability and reliability ■

of your gas turbine to deliver maximum power at base load

Frame and inlet duct-specific coverage ■

via CFD (perfect surface coverage of the first blade row)

Optimized nozzle arrangement ■

(nozzle arrangement on the inner cone only, no inlet duct wall installation)

Optimized droplet size for less erosion ■

and better cleaning effect

Proven and safe nozzle design with ■

locknut and safety plate

Less water and detergent consumption ■

during on-line wash due to optimized nozzle numbers and design compared to the traditional Siemens system (approx. 30% less water and approx. 25% less detergents)

Uncomplicated use of cleaning agents ■

and antifreeze rinsing fluids (all Siemens released cleaning agents and antifreeze rinsing fluids can be used for the ACCSpro system without any restrictions)

Automatic skid with interconnection ■

to instrumentation and control system for information and signal exchange, including operator’s visualization and on-line wash control (optional)

Optional Compressor Wash Prediction ■

(COWAP) analyzer module allows visu-alization and prediction of performance losses and performance recovery, there-by determining the optimal timing for an off-line wash

The Advanced Compressor Cleaning System pro upgrade (ACCSpro) is applicable for the following gas turbine frame types:*

SGT5-4000F (V94.3A) ■

SGT6-4000F (V84.3A) ■

SGT5-3000E (V94.2A) ■

SGT5-2000E (V94.2) ■

SGT6-2000E (V84.2) ■

An even longer-lasting cleaning effect can be achieved in combination with the Siemens Advanced Compressor Coating (ACC) upgrade whereby a special coating provides a smooth blade surface finish in the compressor blades and vanes.

* as of June 2010

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Siemens Energy has successfully implemented the Advanced Compressor Cleaning System pro (ACCSpro) for the first time in Austria in 2008.

More than 20 units with the proven frame-specific Advanced Compressor Cleaning System are in operation worldwide.

References

Conclusion

Permission for use

Disclaimer

Recent improvements in turbine tech-nology have provided major benefits such as increased performance and improved reliability and availability, all of which have made a gas turbine modernization project attractive and highly beneficial for the retrofit in existing power plants.

During the past years Siemens Energy introduced a wide range of enhance-ments on gas turbines within the new unit business as a result of continuous development work.

Due to very successful prototype results of ACCSpro in Austria, the series release for SGT5-4000F (V94.3A) was given in 2008.

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