Field Experience of a Dry Low Emissions Combustion System for Allison 501-K Series of Engines

Author(s):  
Mohan K. Razdan ◽  
Charles S. Bach ◽  
Paul J. Bautista

Allison Engine Company has introduced a dry low emissions lean premixed combustion system, designated LE4, for the 501-K series industrial gas turbine engines. The design goals were 1) to develop a retrofittable combustion system which limits exhaust gas emission levels to less than 25 ppm NOx, 50 ppm CO and 20 ppm UHC while operating on natural gas fuel at full load conditions, and 2) to maintain system cost to less than that for alternate control methods. Extensive in-house engine tests were completed to ensure successful combustion system operation including acceptable engine transient operation during load dumps, and also to optimize the window of operation for emissions performance. These tests have demonstrated engine emissions levels which are below the goals, with NOx less than 15 ppm, CO less than 20 ppm, and UHC less than 10 ppm, all corrected to 15% O2. These emissions can be maintained at the target levels for engine operation from 85 to 100% power. For applications requiring wider power operation, a diffuser bleed system has been engine demonstrated which maintains less than 25 ppm NOx, 50 ppm CO and 25 ppm UHC from 50 to 100% power. The combustion system employs a dual mode combustion approach to meet engine operability requirements and emissions targets. The control algorithm developed for the LE4 combustion system allows easy tailoring of the pilot-to-main fuel ratio schedule setting to meet the customer needs on a site by site basis to account for different ranges of ambient conditions. Use of Streamwise Oriented Effusion Cooling (SOEC) design in the liner wall met the maximum wall temperature goals of less than 1650°F. The LE4 combustion system is operating currently in two applications: 501-KC5 ANR Pipeline application in Woodstock, IL, and 501-KB7 Cogeneration application in Scandiano, Italy. Measured emissions over time and a range of ambients in these engines show NOx, CO and UHC results which are better than the goals. The 501-KC5 engine has accumulated more than 3500 hours, and the 501-KB7 engine has accumulated more than 5500 hours. Both sites have been running with problem free operation, and borescope inspections have indicated excellent condition of the combustion systems.

Author(s):  
Jacob T. McLeroy ◽  
Duane A. Smith ◽  
Mohan K. Razdan

The Allison Engine Company has been developing a low emission, can-annular combustion system for the 501K industrial gas turbine engine to satisfy increasingly stringent environmental requirements. This paper describes the progress achieved, over that previously reported by Razdan et al. (1994), through subsequent design evolution, bench testing, and engine evaluation. Allison’s goal is to develop a retrofittable, can-annular combustion system that limits emission levels to less than 25 ppm nitrogen oxide (NOx), 50 ppm carbon monoxide (CO), and 20 ppm unburned hydrocarbon (UHC), while operating at full load conditions. The interim emissions goals for the combustion system are 37 ppm NOx, 80 ppm CO, and 20 ppm UHC (all dry 15% O2 corrected). The combustion system under development employs a dual mode combustion approach to meet engine operability requirements and high power emission targets without the use of combustor diluent injection or postcombustor exhaust treatment. A lean premixed combustion mode is used to minimize combustion zone temperature and limit NOx production during high power engine operation. The lean premix mode is augmented with a diffusion flame pilot mode for engine starting and low power operation. Initial engine testing showed a dry low NOx combustion system, designed to meet a 37 ppm NOx limit, produced less than 34 ppm NOx and less than 10 ppm CO and UHC in test stand verification test. Continued burner rig testing with modified primary combustion zone stoichiometry has demonstrated NOx less than 25 ppm, CO less than 50 ppm, and UHC less than 20 ppm with simulated engine conditions representing 20 to 100% power. Development activity continues on the combustion system as engine field evaluation trials proceed.


Author(s):  
Marcus H. H. Scholz ◽  
Simon M. DePietro

The second Generation of EGT’s G30 DLE combustion system was introduced after a successful series of high pressure rig and engine tests. This paper covers how operational problems with field commissioning hardware on the lead DLN machine were dealt with, leading to achievement of reliable low NOx hardware. Several changes were applied to the early design which improved the mixing and reduced the effects of high temperature distortion and combustor dynamics. This resulted in increased life of the burner and changed the characteristics of dynamics. It also led to very low emission levels with an outstanding capability for turndown of CO with NOx below 25 ppmvd (15% O2) over the whole load range. Further coverage is given to the effect of field tuning, and of fuel composition on the amplitudes and frequencies of dynamics. The installation has been supported by on-line condition monitoring of engine parameters, emission levels and ambient conditions, which are also discussed. The general overview of site history is followed by a summary of lessons learnt in field comparison to development test bed.


Author(s):  
Luke Cowell ◽  
Colin Etheridge ◽  
Ken Smith

Industrial gas turbine manufacturers began offering engines configured with dry low emissions (DLE) control in 1992. In the past ten years the performance and emissions reductions have been well demonstrated by DLE equipment. To date DLE gas turbines have relied on lean premixed combustion technology to achieve emissions reductions of 8 to 10 fold from “conventional” diffusion flame engines. The significant new content incorporated for DLE combustion systems has required industrial gas turbine manufacturers and users to work with greater synergy to overcome significant challenges. As evidence of this ultimately successful integration, DLE gas turbines are now as common in service as conventional diffusion flame engines. With thousands of DLE units sold one would expect that DLE gas turbines are now a mature product. In many aspects, this is true. However, emissions regulations and other market drivers have continued to change, forcing DLE equipment to continually evolve. A Solar history of DLE gas turbine developments, capabilities, and experiences are provided to give operators background and knowledge to reduce field issues and maximize availability of their DLE gas turbines. Design limitations and problems encountered in the field are discussed along with the steps that were taken to resolve them. Recommendations on DLE engine operation to avoid unscheduled downtime are presented. Design improvements to reduce emissions further and improve system flexibility are summarized.


Author(s):  
U. Gruschka ◽  
B. Janus ◽  
J. Meisl ◽  
M. Huth ◽  
S. Wasif

The lean premixed combustion system was scaled from Siemens 60Hz engine application and optimized for implementation in the new SGT5-8000H 50Hz engine. The Siemens H-class engine is air cooled, uses a pressure ratio of 19:1 and is designed to achieve an efficiency of >60% efficiency in combined cycle operation. This improved dry low NOx system is of can annular type and consists of 16 cans in the SGT5-8000H. It was developed and tested in a full scale, high pressure rig test program. The single can high pressure rig simulates closely the flow conditions upstream of the combustor in the SGT5-8000H midframe and downstream of the combustor at the turbine inlet. The combustion system uses 5 fuel stages which allow flexible tuning over the whole range of engine operation conditions (ignition, idling, part- and base load). The system is designed to operate over a wide range of fuel quality and preheat temperatures. The test program is carried out over multiple years and encompasses rig / engine tests. This paper describes the combustion system in more details and the testing methodology. The test rig results showed that the performance targets are fully achieved in terms of emissions and operational requirements. Furthermore, the development / validation program will continue to reduce emissions through extended programs for future engines.


Author(s):  
Edson Batista da Silva ◽  
Marcelo Assato ◽  
Rosiane Cristina de Lima

Usually, the turbogenerators are designed to fire a specific fuel, depending on the project of these engines may be allowed the operation with other kinds of fuel compositions. However, it is necessary a careful evaluation of the operational behavior and performance of them due to conversion, for example, from natural gas to different low heating value fuels. Thus, this work describes strategies used to simulate the performance of a single shaft industrial gas turbine designed to operate with natural gas when firing low heating value fuel, such as biomass fuel from gasification process or blast furnace gas (BFG). Air bled from the compressor and variable compressor geometry have been used as key strategies by this paper. Off-design performance simulations at a variety of ambient temperature conditions are described. It was observed the necessity for recovering the surge margin; both techniques showed good solutions to achieve the same level of safe operation in relation to the original engine. Finally, a flammability limit analysis in terms of the equivalence ratio was done. This analysis has the objective of verifying if the combustor will operate using the low heating value fuel. For the most engine operation cases investigated, the values were inside from minimum and maximum equivalence ratio range.


Author(s):  
Daniel Lörstad ◽  
Annika Lindholm ◽  
Jan Pettersson ◽  
Mats Björkman ◽  
Ingvar Hultmark

Siemens Oil & Gas introduced an enhanced SGT-800 gas turbine during 2010. The new power rating is 50.5MW at a 38.3% electrical efficiency in simple cycle (ISO) and best in class combined-cycle performance of more than 55%, for improved fuel flexibility at low emissions. The updated components in the gas turbine are interchangeable from the existing 47MW rating. The increased power and improved efficiency are mainly obtained by improved compressor airfoil profiles and improved turbine aerodynamics and cooling air layout. The current paper is focused on the design modifications of the combustor parts and the combustion validation and operation experience. The serial cooling system of the annular combustion chamber is improved using aerodynamically shaped liner cooling air inlet and reduced liner rib height to minimize the pressure drop and optimize the cooling layout to improve the life due to engine operation hours. The cold parts of the combustion chamber were redesigned using cast cooling struts where the variable thickness was optimized to maximize the cycle life. Due to fewer thicker vanes of the turbine stage #1, the combustor-turbine interface is accordingly updated to maintain the life requirements due to the upstream effect of the stronger pressure gradient. Minor burner tuning is used which in combination with the previously introduced combustor passive damping results in low emissions for >50% load, which is insensitive to ambient conditions. The combustion system has shown excellent combustion stability properties, such as to rapid load changes and large flame temperature range at high loads, which leads to the possibility of single digit Dry Low Emission (DLE) NOx. The combustion system has also shown insensitivity to fuels of large content of hydrogen, different hydrocarbons, inerts and CO. Also DLE liquid operation shows low emissions for 50–100% load. The first SGT-800 with 50.5MW rating was successfully tested during the Spring 2010 and the expected performance figures were confirmed. The fleet leader has, up to January 2013, accumulated >16000 Equivalent Operation Hours (EOH) and a planned follow up inspection made after 10000 EOH by boroscope of the hot section showed that the combustor was in good condition. This paper presents some details of the design work carried out during the development of the combustor design enhancement and the combustion operation experience from the first units.


Author(s):  
Samuel Cruz-Manzo ◽  
Vili Panov ◽  
Yu Zhang ◽  
Anthony Latimer ◽  
Festus Agbonzikilo

In this study, a Simulink model based on fundamental thermodynamic principles to predict the dynamic and steady state performance in a twin shaft Industrial Gas Turbine (IGT) has been developed. The components comprising the IGT have been implemented in the modelling architecture using a thermodynamic commercial toolbox (Thermolib, EUtech Scientific Engineering GmbH) and Simulink environment. Measured air pressure and air temperature discharged by compressor allowed the validation of the modelling architecture. The model assisted the development of a computational tool based on Artificial Neural Network (ANN) for compressor fault diagnostics in IGTs. It has been demonstrated that modelling plays an important role to predict and monitor gas turbine system performance at different operating and ambient conditions.


2000 ◽  
Author(s):  
Edward Bass ◽  
Joseph Johnson ◽  
Pat Wildemann

Author(s):  
Matthew E. Thomas ◽  
Mark J. Ostrander ◽  
Andy D. Leonard ◽  
Mel Noble ◽  
Colin Etheridge

CFD analysis methods were successfully implemented and verified with ongoing industrial gas turbine engine lean premix combustion system development. Selected aspects of diffusion and lean premix combustion modeling, predictions, observations and validated CFD results associated with the Solar Turbines Mars™ SoLoNOx combustor are presented. CO and NOx emission formation modeling details applicable to parametric CFD analysis in an industrial design environment are discussed. This effort culminated in identifying phenomena and methods of potentially further reducing NOx and CO emissions while improving engine operability in the Mars™ SoLoNOx combustion system. A potential explanation for the abrupt rise in CO formation observed in many gas turbine lean premix combustion systems is presented.


2019 ◽  
Vol 22 (1) ◽  
pp. 341-348
Author(s):  
Nir Druker ◽  
Gideon Goldwine ◽  
Eran Sher

We propose here a new method to evaluate the mixture charge density inside the combustion chamber of an internal combustion engine. This is an important parameter that is needed to optimize the spark timing and the amount of fuel that is introduced to the cylinder at each cycle, thus optimizing the engine operation for higher power, lower brake-specific fuel consumption, or lower pollutants’ emission at any altitude/ambient conditions. The evaluation of the charge density is performed at each cycle (on a cycle-to-cycle basis) by using the voltage–current characteristics of the spark plug gap. This real-time evaluation method may save two of the present in-use temperature and pressure gages, thus considerably increasing the reliability of the propulsion unit. Owing to the expected higher system reliability and system simplicity, small unmanned aerial vehicles, as well as small automotive engines of various types, may significantly benefit from this proposed method. The method principles, rationale, and some preliminary results are presented.


Sign in / Sign up

Export Citation Format

Share Document