Combustion, Fuels and Emissions for Industrial Gas Turbines
It is important that gas turbines used in Oil & Gas applications can burn a wide variety of fuels with the minimum impact on the environment or economics. Many types of gaseous and liquid fuels that can be used in Gas Turbines are discussed, as will be the two basic types of combustion system employed – ‘conventional’ and ‘Dry Low Emissions’ – along with the flexibility of these systems to accept different types of fuel. Some of the common contaminants found in fuels are discussed along with the impact these have on the operability and maintenance of industrial and aero-derivative gas turbines. Topics include: Types of gas turbines Types of exhaust emissions regulated Conventional combustion systems Dry Low (Pre-mixed) emissions combustion systems Fuel quality requirements ‘Pipeline’ quality Natural Gas fuels Premium liquid fuels (diesel, kerosene) Wellhead Gases as a Gas Turbine Fuel Liquified Natural Gas (LNG) Biogas fuels Refinery and process off gases Syngas Natural Gas Liquids and LPG fuels Crude Oil Operational impact of contaminants Water in fuel Storing fuels correctly
THE NATURE OF NOX FORMATION WITHIN AN INDUSTRIAL GAS TURBINE DRY LOW EMISSION COMBUSTOR
The NOx formation within a practical lean premixed gas turbine combustor concept has been investigated. The effects of chemical kinetics and fuel/air mixing have been isolated, by adopting an approach, which combines high pressure combustion testing, CFD and chemical reactor modelling. Given the complexities of the underlying fluid dynamic and chemical processes and their interactions, consistency has been sought between experimental and numerical approaches, prior to drawing any conclusions. Two variants of Siemens Industrial Turbomachinery’s dry low emissions combustor have been investigated, one exhibiting near-ideally premixed combustion over a wide range of combustor pressure drop. Perfectly Stirred Reactor analysis, utilising the GRI 3.0 NOx mechanism, shows that NOx formation is dominated by the N2O and Zeldovich routes, with the N2O route being the larger at flame temperatures below 1800-1900K, for systems operating at 14bars, 400°C inlet temperature and at residence times of interest. Other reactions involving H-N-O chemistry are also significant, however the CH-N-O chemistry has a negligible impact.
Techno-economic analysis of chemical looping combustion with humid air turbine power cycle
Abstract Power generation from fossil fuel-fired power plant is the largest single source of CO2 emission. CO2 emission contributes to climate change. On the other hand, renewable energy is hindered by complex constraints in dealing with large scale application and high price. Power generation from fossil fuels with CO2 capture is therefore necessary to meet the increasing energy demand, and reduce the emission of CO2. This paper presents a process simulation and economic analysis of the chemical looping combustion (CLC) integrated with humid air turbine (HAT) cycle for natural gas-fired power plant with CO2 capture. The study shows that the CLC–HAT including CO2 capture has a thermal efficiency of 57% at oxidizing temperature of 1200 °C and reducer inlet temperature of 530 °C. The economic evaluation shows that the 50 MWth plant with a projected lifetime of 30 years will have a payback period of 7 years and 6 years for conventional HAT and CLC–HAT cycles respectively. The analysis indicates that CLC–HAT process has a high potential to be commercialised.