Coal-fueled Diesel Engines Research Articles

The General Electric Coal-Fueled Diesel Engine Program (1982–1993): A Technical Review

In the early 1980s, General Electric—Transportation Systems (GE-TS), a manufacturer of locomotive diesel engines, announced plans to develop a coal-fueled locomotive due to the availability and low cost of coal. In 1985 and 1988, the General Electric Company (GE) was awarded major contracts from the Department of Energy, Morgantown Energy Technology Center, to continue the research and development of a coal-fueled diesel engine. This paper is a review of the technical accomplishments and discoveries of the GE coal-fueled diesel engine research and development program during the years 1982–1993. The results of an economic assessment completed by GE-TS indicated the merits for the development of a coal fueled diesel engine for locomotive applications and therefore, GE-TS embarked on an ambitious program to develop and commercialize a coal-fueled diesel engine. Among the major accomplishments of this program were the development of specialized fuel injection equipment for coal–water slurries, diamond compact inserts for the nozzle tips for wear resistance, and an integrated emissions control system. Over 500 hours of engine operation was accumulated using coal fuel during the duration of this program. A major milestone was attained when, during November and December 1991, a coal-fueled diesel engine powered a locomotive on the General Electric test track.

Coal-Fueled Diesel Development: A Technical Review

The purpose of this paper is to describe and summarize the results of the Coal Fueled Diesel Engine Development Program, sponsored by the U.S. Department of Energy, Morgantown Energy Technology Center. The results of the program indicate that diesel engines can be designed to operate reliably on coal–water slurries. The engine must be modified to include hard-wear resistant rings and liners. The injection system design must be modified to accommodate the slurry and to incorporate hard materials for wear prevention.

Wear reduction systems for coal-fueled diesel engines II. Experimental results and hydrodynamic model of powder lubrication

This paper is the second part of an investigation of the mechanism and performance of powder lubrication. In the first part of the investigation (this volume pp. 508–517), the basic features of the quasi-hydrodynamic nature of particulate lubricants were conceptualized and the experimental setup for testing was described. In the tests described herein, load capacity, friction levels, and, most importantly, rates of wear were recorded for a wide range of operating conditions and various surface geometries, materials, and powder lubricants. The test results demonstrate the viability of powder lubrication. The results also corroborate the postulated quasi-hydrodynamic nature of particulate films. In addition, features specific to powder lubrication were brought to light, such as the onset of starvation with time, and the phenomenon of film adhesion. Based on these findings, design requirements for the proper functioning of practical powder-lubricated systems are described. Finally, a hydrodynamic model consisting of a mating surface, intermediate films, and a particulate lubrication film is presented. With these tools developed, analytical or semi-empirical relations should become available for the design of full-scale, powder-lubricated tribosystems.

Wear reduction systems for coal-fueled diesel engines I. The basics of powder lubrication

The objective of this investigation is to resolve the problem of severe wear occurring in systems using coal-water particulates as fuels or as a process material. The approach discussed herein consists of replacing conventional oil lubrication with a powder lubrication system that uses the process particles, either alone or in combination with another powder. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this investigation provide guidelines for selection of the proper geometries, materials, and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. A follow-up paper dealing with the performance and the results of the experimental investigation presents conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication

Coal-Fueled Diesel Engine Development Update at GE Transportation Systems

The U.S. Department of Energy is sponsoring a General Electric Company development program for using coal-water slurry (CWS) to power a diesel engine and to test it in a locomotive. The first locomotive system test was successfully completed in 1991 on GE/TS test track. The first-phase coal-fueled 12-cylinder diesel engine used in the locomotive test employed a modified positive displacement fuel injection system and developed 2500 hp in the engine laboratory. The final phase all electric controlled fuel injection equipment (FIE) diesel engine has completed individual component development phases. Combustion research evaluated a broad range of CWS fuels with different source coals, particle sizes, and ash contents. The electronic controlled FIE single cylinder test engine yielded 99.5 percent combustion efficiency. Envelop filters and copper oxide sorbent have been chosen to clean up the engine emissions after extensive evaluation of various hot gas cleaning methods. The projected removal rate of particulate is 99.5 percent and that of SO2 is 90 percent. Over ten diamond insert injector nozzles performed well on the test engines. A bench test of one nozzle has been run for over 500 engine equivalent hours without significant wear. Tungsten carbide (WC) coated piston rings and cylinder liners were identified to be effective in overcoming power assembly wear. A matrix of WC spray parameters were investigated, and the best process was used to apply coatings onto full scale rings and liners. These and other test parts are currently running in two coal fuel operated cylinders on a converted eight-cylinder endurance test engine. All of these developed technologies will be applied onto the second phase engine and be used in the final phase locomotive test. An economic analysis was also completed on a concept locomotive design. Additional equipment cost and the level of diesel fuel price to repay the investment were analyzed. Thus the economic environment for the commercialization of the modern coal fueled locomotive is defined.

Features and Performance Data of Cooper-Bessemer Coal-Fueled Six-Cylinder LSB Engine

The six-cylinder Cooper-Bessemer LSB engine has been converted to operate with one cylinder on coal-water slurry (CWS) fuel and with five cylinders operating on diesel fuel. This development followed the successful operation of the single-cylinder JS engine on CWS for over 600 hours to date. The CWS injection system was scaled up about a factor of two in fuel volume from the JS system. A new cam box drive was fabricated for the LSB single-cylinder operation. The engine was operated and full power output was achieved from the CWS cylinder. Preliminary test results indicate good operate efficiency. An exhaust emission control system is in place for the proposed operation of all the six cylinders on CWS and major engine components are on hand. These results mark a significant milestone in the progress toward commercial readiness of the coal-fueled diesel engine system.

Abrasive concentration effects on wear under reciprocating conditions

Experiments were conducted to investigate wear under abrasive conditions present at the piston ring-cylinder liner interface in coal-fueled diesel engines. A reciprocating apparatus was designed and fabricated to study the effects on wear of ash content in coal and of abrasive concentration in oil. The wear rate was found to be a linear function of ash concentration regardless of whether the coal had been combusted or not. A linear dependence of wear rate on abrasive concentration in oil was also observed for both coal and pure silica. These effects have important implications on wear mitigation and research methodologies for coal-fueled engines.

Coal-Fueled Diesel Engine Progress at GE Transportation Systems

A coal-fueled diesel engine holds the promise of a rugged, modular heat engine that uses cheap, abundant fuel. Economic studies have indicated attractive returns at moderate diesel fuel prices. The compositions of coal-water fuels are being expanded to cover the major coal sources. Combustion has been developed at 1000 rpm with mechanical and electronic fuel injection. Dual fuel operation can run the engine over the load range. Erosion of fuel nozzles has been controlled with diamond compacts. Wear of piston rings and cylinder liners can be controlled with tungsten carbide coatings. Emission measurements show higher particulates and SO2 and lower NOx, CO, and HC. Particulate and SO2 control measures are being investigated.

Component Wear in Coal-Fueled Diesel Engines

Practical use of coal-fueled diesel engines depends on the improvement of component durability. The wear characteristics of standard materials in the coal-fueled engine were studied first. Candidate wear-resistant materials were sorted by bench-scale tests. The best material combinations were applied to small-scale engine tests for operation on seeded diesel fuel. Components with hard materials and coatings were scaled up for coal-water mixture testing on the locomotive engine. Results indicate practical solutions for ring and liner wear and positive progress toward defining the material requirements for the fuel injection nozzle.

Coal-Fueled Diesels: Systems Development

The U.S. Department of Energy (DOE) Office of Fossil Energy has sponsored research in the area of coal-fueled diesel engines since the late 1970s. The program began as an exploratory effort and has grown into a proof-of-concept program that includes several major medium-speed diesel engine manufacturers. Those manufacturers have identified the utility, industrial cogeneration, and transportation markets as areas in which expensive clean distillate fuel may be displaced by low-cost, domestically abundant coal. The development of a coal-fueled diesel engine system will require the parallel development of coal fuels, engine components, wear and emission control system, and a support infrastructure. Because of notable success in earlier projects of the coal-fueled diesel program, the DOE’s Morgantown Energy Technology Center (METC) recently expanded the program with the award of contracts for two 5-year, proof-of-concept project. These major projects will build on the results of past work to complete development of technology for the commercialization of coal-fueled diesel engines. This paper summarizes progress in the DOE program and planned research to overcome technical and economic barriers to that commercialization.

Environmental Aspects of Coal-Fueled Diesel Engines

Conventional diesel engines are considered by some to be contributors to environmental problems since they emit NOx, a suspected acid rain precursor. Initial testing has shown that CWS-fueled diesels emit substantially reduced NOx emissions. While emissions of particulates and SOx may be potentially higher with coal fuels, assessment of the control technology indicates excellent potential for meeting existing and future standards for these emissions. As a result of activities managed by the Morgantown Energy Technology Center, the economic and technical feasibility of CWS-fueled diesel engines has been determined. Recently, both General Electric and A. D. Little/Cooper Bessemer were selected for 5-year contracts aimed at developing by 1993 the components and subsystems necessary for subsequent private sector demonstration and commercialization of coal-fueled diesel power systems. The development of these CWS-fueled systems will necessitate the application of hot gas cleanup contaminant control technology to ensure that the systems burn coal in an environmentally sound manner. The objective of this paper is to discuss the environmental concerns, emission goals, and the control methodologies, devices, and strategies that will be used to ensure CWS-fueled diesel engines will meet current and potential environmental standards.

Emission Characteristics and Control Technology for Stationary Coal-Fueled Diesel Engines

Emissions of primary concern for coal-fueled diesel cogeneration and electric power plants are nitrogen oxides, sulfur dioxide, particulate matter, and aromatic hydrocarbons. In addition, the exhaust particulate size distribution and ash content are relevant to durability of the exhaust valves, turbocharger, and other engine components. This paper summarizes preliminary measurements of “uncontrolled” emissions in the exhaust of a Cooper-Bessemer 33-cm (13-in.) bore, 400 rpm, single-cylinder research engine, operated on “engine-grade” coal-water fuel (0.5 percent ash, 1 percent sulfur, 8 μm mean size coal). Based on these results, we present a preliminary evaluation of emission control options for satisfying hypothetical future emission standards for 2–50 MW power plants. The paper describes coal-diesel component subsystems such as (a) “reburning” for reducing NOx and hydrocarbon emissions, (b) high- and low-temperature injection of calcium sorbents for SO2 capture, and (c) high-temperature bag filters for control of fine particles. The expected performance of a conceptual, integrated control system is presented.

Coal-fueled diesel engines: Analytical evaluations of ignition options

An engine cycle simulation was developed to investigate the ignition and combustion characteristics of coal-water slurry fuels in a reciprocating, internal combustion engine. The simulation includes models for fuel and air mixing, wall heat transfer, solid coal particle combustion, coal devolatilization, and liquid evaporation and combustion. These models together with a thermodynamic analysis of the cylinder gas yield instantaneous cylinder conditions and overall indicated engine performance. The engine parameters and operating conditions were selected to be representative of a locomotive engine operating at 1000 RPM. Engine and fuel parameters investigated include engine inlet conditions (temperature and pressure), coal particle sizes and size distributions, fuel additives, and coal properties. Increases in the initial (at BDC) gas temperature or pressure, or the addition of small amounts of diesel oil improved the ignition characteristics. Slurries with smaller particle sizes exhibited better ignition qualities and resulted in higher peak indicated thermal efficiencies than slurries with larger particle sizes. Results obtained using monosize sauter mean diameter particles agreed well with results obtained for the corresponding distribution. Finally, ignition was achieved at lower initial gas temperatures for higher reactivity coals.