Atomization Quality of Twin Fluid Atomizers for Gas Turbines

A detailed investigation of the effect of nozzle/needle diameter ratio, normal fuel area, swirler degree, air pressure, fuel pressure on flow number, cone angle and droplet size distribution of external mixing twin fluid atomizers is given in this paper. Forty atomizers have been constructed to prevent mutual effect of various parameters. Flow number and cone angle are found to increase with nozzle/diameter ratio, and to decrease with the increase of air pressure. Optimum fuel flow is obtained at swirler angle 30-deg, while cone angle increases with increase of swirler angle. Sauter mean diameter decreases with the increase of air pressure and decrease of fuel pressure. Suitable functions are derived for droplet size distribution, Sauter mean diameter, and flow number. They are suitable to predict the geometry of the atomizer and to be used also in a prediction model for the calculation of fuel concentration and heat release.

Effect of Using Emulsions of High Nitrogen Containing Fuels and Water in a Gas Turbine Combustor on NOx and Other Emissions

A total of four combustion tests studying the response of various water/fuel emulsion rates on NOx emissions have been conducted on: (a) Paraho shale oil, (b) H-Coal© (372–522 K) distillate, (c) No. 2 oil doped with quinoline, (d) H-Coal© (505–616 K) distillate, utilizing a 0.14 m dia gas turbine can-type combustor at base-load conditions. Each test fuel run was proceeded with a base-line fuel run with No. 2 distillate oil. The results indicate that the effectiveness of water injection to reduce NOx decreased rapidly with an increase in the fuel-bound nitrogen (FBN) content of the test fuels. The smoke number, in general, decreased with increased water injection, while carbon monoxide and unburned hydrocarbons increased at high water/fuel flow rates.

Centrifugal Compressor Testing Experience and Practice

Experience with factory and field performance testing of centrifugal compressors in natural gas service is presented. The ability of different types of factory test arrangements to closely predict future field performance is compared. Instrumentation requirements for achievement of reasonable accuracy in field testing are defined and discussed. Major aspects of mechanical and aerodynamic performance testing are addressed.

Ruhrchemie/Ruhrkohle’s Technical Version of the Texaco Coal Gasifier as Part of a Combined Cycle Plant

The Ruhrchemie/Ruhrkohle variant of the Texaco Coal Gasification Process (TCGP) has been on stream since 1978. As the first demonstration plant of the “second generation” it has confirmed the advantages of the simultaneous gasification of coal: at higher temperatures; under elevated pressures; using finely divided coal; feeding the coal as a slurry in water. The operating time so far totals 9000 hrs. More than 50,000 tons of coal have been converted to syn gas with a typical composition of 55 percent CO, 33 percent H2, 11 percent CO2 and 0.01 percent of methane. The advantages of the process — low environmental impact, additional high pressure steam production, gas generation at high pressure levels, steady state operation, relatively low investment costs, rapid and reliable turn-down and load-following characteristics — make such entrained-bed coal gasification processes highly suitable for power generation, especially as the first step of combined cycle power plants.

Erosion Resistance and Efficiency of Energy Exchangers

Applications of energy exchangers, a type of gasdynamic wave machine, were evaluated in power plants fired by pressurized, fluidized bed combustors (PFBCs). Comparative analyses of overall power plant efficiency indicate that the use of energy exchangers as hot gas expanders may provide a 0.5 to 1.5 efficiency point increase relative to gas turbines. In addition, the unique operating characteristics of these machines are expected to reduce rotating component wear by a factor of 50 to 300 relative to conventional gas turbines operating in the particulate laden PFBC effluent stream.

High-Temperature Turbine Technology Readiness

Final component and technology verification tests have been completed for application to a 2600°F rotor inlet temperature gas turbine. These tests have proven the capability of combustor, turbine hot section, and IGCC fuel systems and controls to operate in a combined cycle plant burning a coal-derived gas fuel at elevated gas turbine inlet temperatures (2600–3000°F). This paper presents recent test results and summarizes the overall progress made during the DOE-HTTT Phase II program.

Application of Heavy Fuel Test Results to Gas Turbine Operation

The results of ash deposition tests with simulated residual oil are presented. Both air-cooled and water-cooled nozzles were tested over a range of firing temperature, fuel contaminant levels, and metal surface temperatures. Extensive ash cleaning tests were also completed under full, steady-state operating conditions. Various online ash removal techniques were tested including small nutshells, large nutshells, coke particles, and water droplets. The results of these tests were applied to a General Electric gas turbine to predict actual field operation at turbine inlet temperatures up to 2300°F (1260°C). Use of on-line ash removal and optimum water washing intervals are shown to significantly improve the economics of gas turbine operation on heavy fuels. The improvements in heavy fuel operation were larger with a water-cooled stage 1 nozzle than with an air-cooled nozzle. This work was jointly sponsored by the Electric Power Research Institute and General Electric under the Advanced Cooling, Full-Scale Engine Demonstration Program.

Combustor Liner Temperature in the Gas Turbine Using Heavy Fuels

Broadening of aviation fuel specifications has been simulated with blends of gas oil and residual fuel oil. Radiation, smoke and temperature measurements in a developed experimental combustor at various air pressures, inlet temperatures and air-fuel ratios permit derivation of a non-dimensional temperature parameter showing good correlation with theory.

An Empirically-Based Simulation Model for Heavy-Duty Gas Turbine Engines Using Treated Residual Fuel

An empirically-based engine simulation model was developed to analyze the operation of a heavy-duty gas turbine on ash-bearing fuel. The effect of the ash in the combustion products on turbine efficiency was determined employing field data. The model was applied to the prediction of the performance of an advanced-cooled turbine engine with a water-cooled first-stage nozzle, when operated with ash-bearing fuels. Experimental data from a turbine simulator rig were used to estimate the expected rates of ash deposit formation in the advanced-cooled turbine engine, so that the results could be compared with those for current engines. The results of the simulations indicate that the rate of decrease in engine power would be 32 percent less in the advanced-cooled engine with water cooling. An improvement in predicted specific fuel consumption performance was also noted, with a rate of increase of 38 percent for the advanced-cooled engine.

The Gas Turbine Heat Exchanger in the Fluidized Bed Combustor

In a current research and development program a coal fired atmospheric fluidized bed combustor is being designed to supply the heat to a closed cycle gas turbine cogeneration system. The major technical effort is directed towards the design of the in-bed heat exchanger, which is required to operate near bed temperature. This high temperature (850 C) exposes the heat exchanger tubes to potentially severe sulfidation. The corrosion behavior depends upon the intimate details of the bed environment and may be related to the occurrence of localized areas of low oxygen partial pressure and high sulfur partial pressure. This paper describes a series of measurements of oxygen partial pressure at various locations within a fluidized bed. The bed, containing densely packed heat exchanger tubes, was operated under various conditions to observe the effect of coal mixing and devolatilization on local oxygen activity. Substantial variations of oxygen partial pressure (below 10−14 atmospheres) were observed. It was noted that these locally severe variations could be substantially modified by changes in coal mixing (as through coal port design). The experiments with varying coal size suggest that rapid devolatilization is desirable and would reduce the extent of locally corrosive environments.