Fuel Effects on the TF30 Engine (Alternate Test Procedure)

The objective of the Alternate Test Procedure (ATP) is to develop the capability to qualify new fuels for Navy aircraft use with a minimum of testing. The effect of fuel composition and properties on engine performance and component life has been shown to vary significantly from one engine configuration to another. The P&WA approach to the ATP has been to define fuel effects on the TF30 engine and then apply the methodology to other engines of interest to the Navy. Investigations of the TF30 conducted under the ATP Program and other Navy and Air Force Contracts have produced one of the most complete fuel effect characterizations available for any gas turbine engine. Major fuel effects which have been quantified are the relationships of lubricity to main fuel control reliability, viscosity and volatility to main burner and augmentor ignition limits, and hydrogen content to smoke and combustor life. The effects of fuel properties and composition on combustion efficiency and elastomeric seal life were found to be of secondary importance. Remaining uncertainties are the effects of fuel properties on turbine life and fuel nozzle fouling rate.

Experimental Evaluation of Simplified IGCC

Integrated gasification combined cycle (IGCC) power plants offer the opportunity to burn coal in an environmentally sound manner at a competitive cost of output energy. Advanced simplified IGCC systems have been identified which offer reduced fuel system capital costs and complexity as well as improved thermal efficiency of coal to fuel conversion. These systems, however, must utilize hot gas cleanup devices to remove particulates, alkali metals, and sulfur to permit utilization of the product fuel gas in a gas turbine. Technology and component development are underway to prepare the hot fuel gas cleanup and gas turbine systems for subsequent integration and verification testing at pilot scale. An experimental testing program is underway to address fuel system and gas turbine components technology for a simplified IGCC configuration. Gas turbine nozzle sectors have been adapted for installation in a turbine simulator for development testing. A low-Btu gas combustor installed upstream of the nozzle sectors is utilized to burn a hot coal gas. Modifications have been made to an existing pilot scale coal gasifier to deliver 1000°F low-Btu coal gas to the gas turbine combustor after partial cleanup by a hot cyclone to remove particulate matter carried over from the coal gasifier. The results from this experimental program will resolve technical issues related to corrosion, deposition and erosion phenomena related to fuel quality, turbine inlet temperature, and nozzle metal surface temperature.

A Nonradioactive Replacement for the Sodium-24 Tracer in Turbine Performance Tests

In the past, expensive measuring devices were used to determine performance and efficiency on nuclear turbine cycles. More recently, sodium-24 replaced these devices because of the reduced cost, increased accuracy and improved precision. While radioactive sodium-24 has significant advantages, it brings with it several disadvantages such as: 1. limited useful working time, 2. exposure of testing personnel to ionizing radiation, 3. limited availability, 4. the need for government licensing which for all practical purposes precludes its use in fossil plants, 5. unacceptable radioactive release to the environment during boiler blow-down, 6. complex analysis procedure. Thus, a nonradioactive replacement for sodium-24 has become economically desirable as well as necessary from the ease of use point of view. In this paper, the procedure for choosing a nonradioactive replacement tracer will be discussed with reference to the criteria needed to be satisfied for an adequate tracer e.g., a suitable and sensitive analytical detection technique that would be already available to power plants. Necessary refinements to the sodium-24 testing procedure will also be discussed as well as a unique means of preconcentrating the tracer prior to analysis. The laboratory evaluation and method development to be discussed in the paper was funded by EPRI. The potential applications for the new tracer, which include all sodium-24 uses, will be noted. These uses include, but are not limited to component performance, heater leakage, and moisture calculations. Because federal licensing of the nonradioactive tracer is not necessary, tests in a fossil plant are possible and will also be discussed. The completed laboratory experiments indicate high promise for success in actual field tests which are scheduled for mid-1984 for fossil plant testing, and mid-1985 for nuclear station testing.

300 MW Combined-Cycle Plant With Integrated Coal Gasification

In the past 15 years the combined-cycle (gas/steam turbine) power plant has come into its own in the power generation market. Today, approximately 30 000 MW of power are already installed or being built as combined-cycle units. Combined-cycle plants are therefore a proven technology, showing not only impressive thermal efficiency ratings of up to 50 percent in theory, but also proving them in practice and everyday operation (1) (2). Combined-cycle installations can be used for many purposes. They range from power plants for power generation only, to cogeneration plants for district heating or combined cycles with maximum additional firing (3). The main obstacle to further expansion of the combined cycle principle is its lack of fuel flexibility. To this day, gas turbines are still limited to gaseous or liquid fuels. This paper shows a viable way to add a cheap solid fuel, coal, to the list. The plant system in question is a 2 × 150 MW combined-cycle plant of BBC Brown Boveri with integrated coal gasification plant of British Gas/Lurgi. The main point of interest is that all the individual components of the power plant described in this paper have proven their worth commercially. It is therefore not a pilot plant but a viable commercial proposition.

Unsteady Flow at the Outlet of the High Specific Speed Centrifugal Compressor Impeller

The unsteady flow at the outlet of the high specific speed mixed flow Impeller was studied. The specific speed is 500 (m3/min)1/2 · rpm · m−3/4. The flow is strongly influenced by the impeller blading. The other hand, the flow influences the performance of the stationary vanes downstream of the impeller. The flow path at the outlet of the mixed flow impeller is inclined to the axial direction and is curved in the meridional plane. The study was carried out to develop the 30 MW centrifugal compressor. This compressor is used in the field of the coal gasification, the geothermal power generation, etc. The distributions of flow velocity, pressure and temperature of three dimensional flow were measured using a high sensitive pressure transducer and a total temperature probe. The flow was surveyed across the entire passage at about ten axial locations including endwall boundary layer. A theoretical analysis was also carried out using the linearized Navier-Stokes equation.

On Prediction of Off-Design Multistage Turbine Pressures by Stodola’s Ellipse

The variation of extraction pressures with flow to the following stage for high backpressure, multistage turbine designs is highly non-linear in typical cogeneration applications where the turbine nozzles are not choked. Consequently, the linear method based on Constant Flow Coefficient, which is applicable for uncontrolled expansion with high vacuum exhaust as is common in utility power cycles, cannot be used to predict extraction pressures at off-design loads. The paper presents schematic examples and brief descriptions of cogeneration designs, with background and theoretical derivation of a more generalized “nozzle analogy” which is applicable in these cases. This method is known as the Law of the Ellipse. It was originally developed experimentally by Professor Stodola and published in English in 1927. The paper shows that the Constant Flow Coefficient method is really a special case of the more generalized Law of the Ellipse. Graphic interpretation of the Law of the Ellipse for controlled and uncontrolled expansions, and variations for sonic choking and reduced number of stages (including single stage) are presented. The derived relations are given in computer codable form, and methods of solution integral with overall heat balance iteration schemes are suggested, with successful practical experience. The pressures predicted by the relations compare favorably with manufacturers’ data on four high-backpressure, cogeneration cycle turbines and three large utility low-pressure ends.

Methanol as a Soot Reducer in a Turbulent Swirling Burner

The combined effect of using methanol as a fuel additive together with a prototype multifuel injector has been evaluated with regard to soot formation in a tubular laboratory burner with a turbulent swirl stabilized diffusion flame. Kerosene, ERBS fuel and Blending Stock with approximately 14, 12.8 and 10.3 wt% of hydrogen respectively were characterized in terms of soot loading at the axial positions Z/D = 2.5 and 4.0 and normalized radius r/R = ±0.67. Mixtures of ERBS fuel and Blending Stock with 15 and 7.5 wt% of methanol were also characterized in the same way. Measurements with the plain fuels showed a drastic reduction in soot formation, in the order of one hundred and fifty fold decrease, due to the new injector design. Further reductions by a factor of 2 and 1.5 were accomplished with the mixtures of 15 and 7.5 wt% of methanol respectively.

Combined Cycle Retrofit can Also Uprate Steam Plant Capability

A simple, low cost approach to uprating existing steam plants is presented. The proposed uprating eliminates or reduces much of the boiler and turbine work required by conventional uprating methods. Waste heat from a gas turbine’s exhaust can be transferred into the steam cycle of an existing plant creating a combined-cycle unit with greater output than the combined capabilities of the two independent units and improved overall efficiency. When using or relocating an existing gas turbine the cost of the additional midrange capacity (steam plant uprate plus gas turbine) will be far less than the cost of new fossil capacity. The additional capacity is gained without creating a new emissions source.

Utility Combustion Turbine Evaluation of Coal Liquid Fuels

A comprehensive field test was performed to evaluate the suitability of H-Coal middle distillate and full-range Exxon Donor Solvent (EDS) coal derived liquids (CDLs) as utility combustion turbine fuels. A Westinghouse W251AA 26 MW combustion turbine operated by the Philadelphia Electric Company was the test engine. No. 2 petroleum distillate fuel was also fired to establish baseline data. This program was sponsored by the Electric Power Research Institute. Site modifications included a temporary CDL storage and fuel transfer system, water storage and injection equipment, an instrumented combustor, engine and emissions instrumentation and data acquisition systems, and industrial hygiene facilities required for the proper handling of the CDLs. The overall results of testing were positive for using such CDL fuels in combustion turbines for power generation. With the exception of higher combustor metal temperatures with the CDLs, and persistent fuel filter plugging with the EDS fuel, (which occurred even with increased fuel temperature and filter size), the engine operated satisfactorily during approximately 80 hours of total running over the standard range of load and water injection conditions.

Redesigned 26-Inch Last-Stage for Improved Turbine Reliability and Efficiency

Since its introduction in the mid-1950s, General Electric’s 26-in last stage bucket for large steam turbines has proven to be a popular and durable design. Since that time, however, major advances have been made in aerodynamic and structural design methods and manufacturing technology. This paper describes an improved 26-in. last-stage bucket which has been developed for application to new large steam turbines and as replacement rows in operating units. The new bucket is a design having continuous coupling at the outermost periphery and near the midpoint of the vane, and benefits the user through substantial efficiency gains and improved reliability margins.