Power-Gen International 2008 Orlando, Florida

www.siemens.com

Power-Gen International 2008—Orlando, Florida

TECHNOLOGY

ULTRA LOW NOX COMBUSTION TECHNOLOGY

h-to m x-s recently dem-onstrated at Idaho Power's Evander Andrews site.

Clifford Johnson, Barton Pepperman, Michael Koenig, Khalil Abou-Jaoude, Anil Gulati, Ali Moradian

Siemens Power Generation Inc., 4400 Alafaya Trail, Orlando, FL 32826-239 Greg Hall

Idaho Power, Boise, Idaho

Abstract

Siemens Power Generation combustion technology has under-gone a significant transformation over the past 20 years. Evolv-ing from the 1980's diffusion flame combustor technology, whic produces a very stable flame, but is associated with relatively higher levels of emissions output of some constituents, Siemens Power Generation incorporated material and technological design advancements, industry-leading design engineers, and state of the art design tools to develop a successful Dry Low NOx (DLN combustion system in the 1990's. Dry Low NOx technology pro-vides reduced NOx emissions through a staged combustion proc ess and unique temperature and heat release strategy. This fo stage premixed combustion process is designed to produce r able and stable combustion, with lower level emissions and is currently installed in over 100 Siemens GT's. Further improvin the environmental compatibility of Siemens Power Generation fleet of gas turbines, the Dry Low NOx technology has evolve into a combustion system, commercially offered as “Ultra Low NOx “(ULN), which is designed to achieve sub 9 ppm NOx em sions. In addition to stable combustion, the Ultra Low NOx sy tem is characterized by a five stage prem

e

Demonstration of Siemens Power Generation's combustion tec nology is typically extensive, following a detailed design, rig and field test, and then full scale engine testing process, which lead commercial introduction. The Ultra Low NOx combustion syste has been introduced into the commercial fleet, and operating e perience with it has included high GT efficiency and sub 9ppm NOx emissions, across a wide operating range, a

4 5 7 8 r...9 ... Permission for Use...10 References...11

Contents

Introduction... Combustor Design Features... Operation... Testing and Verification... Field Validation – Idaho Powe

Introduction

s, Siemens flexible, requirements mixed combustion

The ULN de-ting fleet. obust Dry ng in SGT6-501F, and W501G) combustion nd opera-] ns, Siemens has lopment of the onstrated w NOx emis-ustor design produces lower CO, VOC and particulate emissions. In combination with the Siemens low load CO system, this combus-tion system is capable of producing single-digit CO emissions down to 40% load. Additionally, the ULN design can meet these requirements for a wider range of fuels, including LNG. [2].

Building upon its history of advanced gas turbine combustion system has developed a robust Ultra-Low NOx (ULN) combustor design for able power generation is designed to meet the stringent emissions in the U.S. and abroad. This configuration utilizes a highly pre system that was designed for SGT6-5000F and W501F engines. sign is applicable for new units and is also retrofittable to the exis The Siemens ULN technology is derived from the well-proven and r Low NOx (DLN) combustion system design that has been operati 3000E, SGT6-5000F, and SGT6-6000G (W501D5/D5A, W

engines for more than 10 years. Recent enhancements to the DLN system have contributed to the world-class reliability, performance a tional flexibility of the newest Siemens SGT6-5000F gas turbines. [1 In response to market requirements for even lower NOx emissio leveraged this DLN design and operating experience into the deve next-generation ULN combustion system technology, which has dem sub-9ppm NOx emissions for F-class engines. In addition to the lo sions, the ULN comb

Combustor Design Features

or basket, pilot fuel is injected

to two fuel etween the C-premix pilot stage.

) utilize swirler es this com-injection holes in the swirler vanes, enhanced fuel/air mixing is achieved, thus reducing the peak temperature of local hot spots that contribute to NOx production. In addition to improved emissions, this design is capable of handling a wide range of fuel composition and fuel temperature.

The ULN combustion system shown in Figure 1 comprises a combust nozzle, support housing, C-stage fuel nozzle, and transition. Most of the through eight main fuel nozzles in the support housing, which is divided in stages of four main nozzles each. The remainder of the fuel is divided b stage and the pilot. The pilot nozzle includes a diffusion stage and a The premix pilot (D-stage) and the two main fuel stages (A and B stages fuel injection (SFI) technology, which is the key design feature that enabl

bustor design to achieve sub-9ppm NOx emissions. By injecting fuel through multiple

.

sing was tested in 2004 he mechanical nozzle bodies were esign, the main fuel

he pilot nozzle bustor basket (Figure 5) are very similar to the design that was tested in 2004. The ULN combustor basket incorporates design features from the proven DLN combustion system that has demonstrated the ability to operate at ex-tended service intervals.

Since the original engine test of this system in 2004 [3], the support hou graded to add dual fuel capability. The original gas only design that was is shown in Figure 2. To accommodate the fuel oil tubing and increase t robustness of the fuel nozzles, the production support housing main redesigned as shown in Figure 3. As in the initial support housing d nozzles were designed to minimize CO production during loading. T (Figure 4) and com

Figure 2: Original Gas Only Support Housing

Figure 3: Dual Fuel Support Housing

Production nozzle body

Figure 4: Dual Fuel Pilot Nozzle

Figure 5: Combustor Basket

Operation

Table 1 shows the fuel staging used for the ULN combustion system. S ignition is performed with fuel split between the diffusion pilot and main adjusted between these two stages to maintain stability during accelera speed. Near synch sp

imilar to DLN, A-stage. Fuel is

tion to synch eed, the D-stage fuel is added. Below 25% load, the CO

emis-sions are minimized by inje only the pilot, A and D-stages. B-stage

fuel is introduced at 25% load to provide more uniform thermal loading and lower NOx emissions. Above 45% load, C-stage fuel is introduced to provide additional stability in the high load range. At high loads, 70-90% of the fuel is injected through the main fuel nozzles, with the remainder of the fuel being divided between the other fuel stages to provide the optimum tuning for low NOx and CO emissions while maintaining combus-tion dynamics below limits.

Table 1: Fuel Staging cting fuel through

Engines with the ULN combustion system are equipped with an active c namics protection system (CDPS SPPA-D3000) that continually monitor tion dynamics levels and the engine emissions. After initial tuning of the commissioning, the engine controller makes automatic real-time adjustm fractions to maintain low emissions while protecting the engine against namics. If the dynamics and NOx readings are within the allowable ran taken. If NOx emissions exceed the target value (e.g., due to a change position or ambient temperature change), then the contro

ombustion dy-s the combudy-s- engine during

ents to the fuel combustion

dy-ge, no action is in the fuel com-ller automatically modulates

y changes to A value, then the in dynamics levels within limits.

Dual fuel operation with a ULN combustion system is very similar to DLN dual fuel op-eration. The engine can be started with either gas fuel or oil fuel. Transfers between gas and oil can be performed up to 70% load.

a combination mbustion rig testing and

performed e was

success-ribed above, ber of design an high pressure

ility, a highly in-The verification NOx and sub-10ppm CO emissions were demonstrated for part load as well as base load operation. On oil fuel, sub-42ppm NOx and sub-10ppm CO emissions were dem-onstrated over the same load range. Fuel transfers between gas and oil were per-formed over a wide range of part load operation.

More than 500 operating hours of validation and verification were performed between the first ULN demonstration and the final engine verification at the Siemens Berlin Test Facility prior to commercial release of the ULN design for production.

the D-stage fraction to reduce NOx, with the balance of the fuel offset b and B stages. If the combustion dynamics levels exceed the threshold D-stage fraction is adjusted to mainta

Testing and Verification

As discussed in [3], the ULN combustion system was developed through of modeling with computational fluid dynamics, high pressure co

engine verification. A series of high pressure combustion rig tests were throughout the development of the first engine hardware. This hardwar fully demonstrated in an engine test on a SGT6-5000F in 2004. As desc the production design incorporated dual fuel capability as well as a num enhancements. These design enhancements were tested in a single c

combustor test rig to assess impacts on emissions and combustion dynamics. Final engine verification was performed at the Siemens Berlin Test Fac

strumented full scale SGT6-5000F engine, which operates at full load.

test at Berlin Test Facility included both gas and oil operation. With gas fuel, sub-9ppm

Field Validation – Idaho Power

Following the final engine verification testing at the Berlin Test Facility en commercial application of the ULN combustion system was commissio Power Evander Andrews project, Mountain Home, Idaho, a simple cycl First fire of this unit occurred in February, 2008. The unit ha

gine, the first ned at the Idaho

e SGT6-5000F). s performed as expected

ellent starting ulty.

nd part load per-ormance

emissions for le combustor dynamics operating range. Figure 7 shows the turndown from 60% to base load. This performance has been consistently demonstrated at the Evander Andrews project for a period of over 6 months, totaling more than 250 EBH and 25 ES. During this time, operation has been validated over a wide range of ambient operating conditions.

based upon Berlin Test Facility results. In particular, the engine has exc reliability, and base load was achieved without any operational diffic During commissioning, the unit successfully demonstrated base load a formance with NOx emissions < 9ppm and meeting all contractual perf quirements. Figure 6 demonstrates that the ULN system meets <9ppm base load operation in the acceptab

6 7 8 9 NOx (ppmvd @ 15% O2) Co mbus nam ics Amplitude

Acceptable Combustion Dynamics Operating Range Combustion Dynamics Alarm Limit

Figure 6: Combustor Dynamics at Base Load

to

0 3 6 9 12 15 50 60 70 80 90 100 110 Load % Em issions ppm vd @ 15%O2 NOx CO

Figure 7: ULN Emission Results

eing offered commercially. The first commissioning effort of this engine at the Idaho Power Evan-der Andrews project was very successful, meeting all contractual performance guar-antees. Emissions levels below 9ppm NOx and 10ppm CO were achieved for part

peration. The lessons learned and methodology applied in the ent of new

Sie-Permission for Use

The content of this paper is copyrighted by Siemens Power Generation, Inc. and is licensed only to PennWell for publication and distribution. Any inquiries regarding permission to use the content of this paper, in whole or in part, for any purpose must be addressed to Siemens Power Generation, Inc. directly.

Summary

The Siemens ULN combustion system has been validated and is now b

load and base load o

development of this combustion system are being used for developm mens gas turbine products.

1. Kovac, J., Xia, J., “SGT6-5000F Technology Enhancements”, POWER-GEN

Interna-., Nag, PInterna-., Abou-Jaoude, KInterna-., Wu, JInterna-., LaGrow, MInterna-., “Liquefied Natural Gas -GEN

Interna-3. Bland, R., Ryan, W., Abou-Jaoude, K., Bandatu, R., Haris, A., Rising, B., 2004, F Gas Turbine : Ultra Low NOx Combustion System Development”, POWER-GEN International 2004.

References

tional 2007. 2. Engel, J

(LNG) Flexibility Solutions for Large-Scale Gas Turbines”, POWER tional 2007.