Combustion and Deposition, Erosion, and Corrosion Tests of Coal Turbine Fuels

This paper discusses the results obtained from the rich-quench-lean (RQL) combustion system running on distillate fuel and coal water slurry (CWS). Estimates of fuel bound nitrogen (FBN) yield indicate that rich lean combustion is successful in reducing the yield from coal water slurry fuel to between 8% and 12%. Some improvements in combustion efficiency are required when burning coal water slurry to reduce carbon monoxide and unburned hydrocarbons to acceptable levels. These improvements are achievable by increasing the lean zone residence time. Further testing is planned to investigate the effects of residence time in more detail. The planned deposition, erosion, and corrosion (DEC) testing will evaluate alternative approaches for protection from deposition, erosion, and corrosion of turbines operating with coal derived fuels.

Simplified IGCC With Hot Fuel Gas Combustion

Experimental testing and data analysis performed for simulated simplified IGCC system components have been completed. Earlier papers presented the program description and preliminary testing operations. This paper presents a review of the testing accomplishments and the results of data analysis. An air-blown, fixed-bed coal gasifier, and downstream cyclone particle separator were found to retain or remove coal ash particles and alkali metals very effectively. The low calorific fuel gas delivered to a gas turbine combustor was found to be significantly closer to the current “clean fuel” specification than had been anticipated. These results are very encouraging for the further development of simplified IGCC systems utilizing hot gas cleanup. Observed ash deposition rates imply that turbine cleaning would be less frequent by at least an order of magnitude as compared to operation on treated ash-forming petroleum fuels.

Utility Applications of Pressurized Fluid-Bed Combustion Systems

The IEA-Grimethorpe pressurized fluid-bed (PFB) pilot plant has recently completed 3,600 hours of testing, the results of which provide valuable design information for the commercial application of PFB systems to utility applications. This paper presents the particular results of the Grimethorpe tests which relate to the design needs of coal-fired power plants and an assessment of the impact on plant design. The application of results to the construction of new and retrofit power plants is discussed. Also discussed are those aspects of the Grimethorpe results which impact the economics of advanced coal-fired power plant operations.

Design and Expected Performance of 45 MWe to 100 MWe CAES Turbine Machinery

The design of 220 Mwe CAES commerical turbine machinery is well known to many U.S. Utilities. Not as well known is the design and expected performance of smaller size CAES units in the 45 to 100 MWe size range. The attributes of the machinery for the smaller sizes are described in this paper. Both the 220 MWe size as well as the smaller sizes are patterned after the successfully operating BBC Brown Boveri designed and fabricated CAES turbine installed at Huntorf, West Germany.

Wetness and Efficiency Measurements in L.P. Turbines With an Optical Probe as an Aid to Improving Performance

An absolute value for the wetness fraction in a partially condensed steam flow may be calculated from measurements of light transmission using the results of fundamental electromagnetic scattering theory. A probe is described that uses this principle for measuring radial wetness profiles in the final stages of L.P. turbines. Results are presented to show that the probe will provide reliable values for overall L.P. turbine efficiency and valuable diagnostic data on the performance of individual stages operating with wet or condensing flows.

A Gas Turbine Interactive Design System — TDSYS — for Advanced Gas Turbines

The characteristics and experiences of the gas turbine interactive design system, TDSYS, are described. The design of high performance advanced gas turbines requires complex trade-off analyses for optimization and hence it is necessary to use a highly efficient and accurate computerised integrated design system to complete the laborious design jobs in a short time. TDSYS is an interactive design system which makes extensive use of computer graphics and enables the designers to complete a gas turbine blade design systematically in a very short time. TDSYS has been developed and continuously improved over a period of ten years. The system has been used for the complete and retrofit design of many gas turbines including Mitsubishi MW701 and AGTJ-100A which is a high efficiency reheat gas turbine now being developed under a Japanese national project. In this paper, typical design samples of high temperature turbines are also presented.

Sulfur/Alkali/Calcium Oxide Sorbent Interaction in Pressurized Coal Combustors

Modeling and bench-scale experiments have been performed related to the capture of fuel-bound sulfur by calcium-based sorbents injected into pressurized coal combustors. Sorbent types tested include two limestones, a dolomite, a slaked lime, and a pressure-hydrated dolomite, with and without several sodium-based mineral promoters present. Sulfur capture data have been obtained at pressures up to 10 atm. These data have been incorporated into the porous sorbent model of Simons and Garman (6). Modeling of lean turbine combustors indicates that in-situ injection of pressure-hydrated sorbents should remove greater than 50 percent of the SO2 at 10 atm and 0.5 sec residence time. Furthermore the presence of alkali minerals in the coal can enhance the intrinsic reactivity by a factor of two or more. Conveniently, the calcium sorbent can serve as a site for alkali condensation and removal.

Power Generation Through Coal Gasification: An Overview of DOE-Funded Projects

The U.S. Department of Energy is currently sponsoring a variety of projects aimed at developing advanced systems for power generation using coal gasification as the central conversion process. These systems include both gas turbines and fuel cells as power generating devices and emphasize hot gas cleanup for equipment protection and environmental control from coal contaminants. Gasification projects in the DOE program cover a range of scales from laboratory investigations to PDU scale plants. Fundamental studies of gasification reactions, ash chemistry, transport processes, and modeling are being conducted to uncover potential improvements that may be made to gasification processes and to ways of reducing cleanup burdens on downstream equipment. Several PDU scale projects are being sponsored to further promising processes. Gas stream cleanup emphasize hot control of particulates, sulfur, alkali, and trace species which may damage power generation equipment. A systems approach has been adopted in formulating strategies for these programs. This approach and brief description of projects in gasification and cleanup will be presented.

Gravel Bed Combustor for Solid Fuel Fired Gas Turbine

A fixed bed, downdraft combustor for solid fuels applicable to gas turbine cogeneration or combined cycles is described. The combustor has a refractory gravel bed, with fuel placed on top of the gravel and burning at the fuel-gravel interface. The gravel retains fuel particles in the combustion zone, preventing carryover of unburned char. Combustion temperature is held below the ash fusion temperature by using high excess air through the bed, thereby minimizing particulate ash agglomeration. Previous work on fixed bed, downdraft combustors and coal fired gas turbines is reviewed. Recent results from test firing a 480 cm2 (0.5 ft2) gravel bed combustor at atmospheric pressure with 2 cm (0.75 in.) wood chips are presented. Heat release rates of 3500 MJ/hr m2 (300,000 Btu/hr ft2) and higher were obtained. Carbon carryover in the exhaust was negligible. Approximately 85 percent of the particulate ash emissions was less than 10 microns.

Staged Combustion of CWM Fuel

The prognosis for electric power generating capacity and for electric power consumption forcasts a problem of power deficits in the future. A solution to that problem may be found in the conversion of existing and future oil and gas fired units to accept coal as the principle fuel. It is recognized that the gas turbine engine can represent a substantial response to the potential electric power deficit problem; consequently, providing a coal-based fuel compatible with gas turbine systems may be of great importance. Technological problems will be encountered in substituting a coal-water slurry for the currently-used more tractable gas turbine fuels. These problems include the design of both fuel injectors that provide desirable fuel distribution and atomization characteristics, and of combustors with broad ranges of stability. Moreover, it must be recognized that the bound nitrogen in coal will produce unacceptable levels of nitrogen oxides unless special combustion techniques are used. Thus, efforts must be undertaken to develop acceptable coal-water fuel specifications, establish the viability of burning coal-water mixtures in gas turbines, and establish a data base for ultimate use in combustion system design procedures.