The Effect of Alternative Turbine Cooling Schemes on the Performance of Utility Gas Turbine Powerplants

It is important that the requirements and cycle penalties related to the cooling of high temperature turbines be thoroughly understood and accurately factored into cycle analyses and power plant systems studies. Various methods used for the cooling of high temperature gas turbines are considered and cooling effectiveness curves established for each. These methods include convection, film and transpiration cooling using compressor bleed and/or discharge air. In addition, the effects of chilling the compressor discharge cooling gas are considered. Performance is developed to demonstrate the impact of the turbine cooling schemes on the heat rate and specific power of Combined–Cycle power plants.

NOx Results From Two Combustors Tested on Medium BTU Coal Gas

This paper describes the results of combustion tests of two scaled burners using actual coal gas from a 25 ton/day fluidized bed coal gasifier. The two combustor configurations studied were a ceramic-lined, staged rich/lean burner and an integral, all metal multi-annular swirl burner (MASB). The tests were conducted over a range of temperatures and pressures representative of current industrial combustion turbine inlet conditions. Tests on the rich lean burner were conducted at three levels of product gas heating values: 104, 197 and 254 Btu/Scf. Corresponding levels of NOx emissions were 5, 20 and 70 ppmv. Nitrogen was added to the fuel in the form of ammonia, and conversion efficiencies of fuel nitrogen to NOx were found to be on the order of 4 to 12 percent, which is somewhat lower than the 14 to 18 percent conversion efficiency when SRC-II liquid fuel was used. The MASB was tested only on medium Btu gas (220 to 270 Btu/Scf), and produced approximately 80 ppmv NOx at rated engine conditions. It is concluded that both burners operated similarly on actual coal gas and ERBS fuel, and that all heating values tested can be successfully burned in current machines.

Rotary Turbine Stage Moisture Separators

This paper deals with new moisture removal methods in wet vapor turbines of nuclear power stations: moisture separation effectiveness of turbine stages, and separators with freely rotating moving wheels. The stage moisture separators may be installed in the turbines of nuclear power stations; other applications include: the gas, chemical, and other branches of industry.

Droplet Size Effects on NOx Formation in a One-Dimensional Monodisperse Spray Combustion System

A one-dimensional monodisperse aerosol spray combustion facility is described and experimental results of post flame NO/NOx emissions are presented. Four different hydrocarbon fuels were studied: isopropanol, methanol, n-heptane, and n-octane. The results indicate an optimum droplet size in the range of 48–58 microns for minimizing NO/NOx production for all of the test fuels. This NOx behavior is associated with droplet interactions and the transition from diffusive type of spray burning to that of a prevaporized and premixed case. Decreasing the droplet size results in a trend of increasing droplet interactions, which suppresses temperatures and reduces NOx. This trend continues until prevaporization effects begin to dominate and the system tends towards the premixed limit. The occurrence of the minimun NOx point at different droplet diameters for the different fuels appears to be governed by the extent of prevaporization of the fuel in the spray, and is consistent with theoretical calculations based on each fuel’s physical properties.

Development Towards a Fuel Flexible Combustion System

Due to limited reserves of crude oil and natural gas, it is generally accepted that fuel prices will continue to rise. Associated with cost increase is a strong possibility that quality of petroleum distillate fuels will deteriorate, particularly for power generation. Several techniques are available or are being developed to produce fuels from non-petroleum sources, including liquids and gases from coal and vegetation. Liquid fuels will fall into two categories: a synthetic distillate with lower hydrogen content and a significant amount of fuel-bound nitrogen unless further hydrogenation is carried out; and light alcohol fuels with lower calorific values than present distillates. Gases produced will vary considerably dependent on the process and original material, but a common factor will be medium to low calorific values in terms of Btu/scf and a tendency to have high inert gas content. The efficiency of energy conversion of various materials is higher when gas is produced (70–85%) than liquid (40–65%). The efficiency of conversion being the ratio of the available energy from the products to the input energy of the feed.

Effect of Gas and Metal Temperatures on Gas Turbine Deposition

A number of test projects have measured the deposition rates of the combustion products of residual-oil-type fuel. This paper analyzes those results to obtain information on he effects of the gas and metal temperatures on the deposition rates. While the data is far from complete, certain major trends result from the data. For a given gas temperature, the deposition rate increases with decreasing metal temperature below the level of the gas temperature until a maximum rate is reached at ∼1200°F (650°C); then the deposition rate decreases as the metal temperature is further lowered and becomes small at metal temperatures near 700°F (370°C). For a given metal temperature, the deposition rate increases with higher gas temperatures. This may occur at an increasing rate for gas temperatures above 2000°F (1100°C).

Interim Rig Test Results of an Advanced-Cooled Utility Turbine Combustor Burning a CDL Fuel

Under the “Advanced Cooling Full-Scale Engine Demonstration” Program, the Electric Power Research Institute, Inc. is developing a combustor fabricated from Lamilloy, to be used in a Westinghouse W501 industrial combustion turbine on coal derived or residual fuel, which is aimed at using less cooling air and improving reliability. A Full-Scale Rig Test Program of the Lamilloy combustor is being conducted at the Westinghouse Combustion Turbine Systems Division. Combustion rig tests have been performed on the full-size Lamilloy combustor on a low hydrogen coal-derived liquid and on standard #2 distillate fuel. The Lamilloy combustor is a multiple laminate porous structure, formed from three diffusion bonded, etched Hastelloy-X sheets. Preliminary test results are given for both fuels and include wall temperatures, emissions and combustor performance for burner outlet temperatures up to 2200°F. Acceptable wall temperature levels were obtained for both fuels, using cooling air flows below those required for the conventional film cooled design. Reduced cooling air requirements permitted larger diluent air flows and a corresponding reduction in pattern factor.

Techniques for Enhancing Durability and Equivalence Ratio Control in a Rich-Lean, Three-Stage, Ground Power Gas Turbine Combustor

This effort summarizes the work performed under Task IV, Sector Rig Tests of the CRT - Critical Research and Support Technology Program, a Department of Energy funded project. The rig tests of a can-type combustor were performed to demonstrate two advanced ground power engine combustor concepts: steam cooled rich-burn combustor primary zones for enhanced durability; and variable combustor geometry for three stage combustion equivalence ratio control. Both concepts proved to be highly successful in achieving their desired objectives. The steam cooling reduced peak liner temperatures to less than 800 K. This offers the potential of both long life and reduced use of strategic materials for liner fabrication. Three degrees of variable geometry were successfully implemented to control airflow distribution within the combustor. One was a variable blade angle axial flow air swirler to control primary airflow while the other two consisted of rotating bands to control secondary and tertiary or dilution air flow.

Full Scale Catalytic Burner Testing With No. 2 Oil for Combustion Turbine Application

Full scale laboratory tests were performed by the Combustion Turbine Systems Division of the Westinghouse Electric Corporation to explore the feasibility of using catalytic burners in industrial combustion turbines to reduce emissions. Catalytic elements were provided by the Engelhard Industries Division of Engelhard Corporation, and No. 2 distillate fuel was burned in single combustor rig tests at the pressure, airflow, and inlet temperature equivalent to those in a large combustion turbine. Variations of a concept that employed a conventional preburner upstream of a catalytic secondary, and sidewall fuel injection were tested and evaluated for fuel/air presentation to the catalyst. Results indicated ultra-low NOx emissions and that, with development in secondary fuel/air preparation, the concept is technically feasible.

Advancing the Technology of the Large Utility-Size Gas Turbine Burning Coal-Derived Fuel

This paper describes the status of the developmental activities underway for advanced, utility-sized gas turbines. These long range, high risk activities initiated in the 1970s in response to the energy crisis situation, have not yet reached a sufficient maturity level to guarantee timely commercial implementation of the developing technology. Technological hurdles still remain to be addressed if the original programmatic goals are to be achieved and the efficiency, hence the economic, benefits are to be gained.