Tuncel M. Yegulalp

A REVIEW OF EMERGING TECHNOLOGIES FOR SUSTAINABLE USE OF COAL FOR POWER GENERATION

Concerns about climate change and environmental consequences of increased levels of atmospheric CO 2 will require the power generation industry to reduce CO 2 emissions from current levels. Unfortunately, for reductions to have the desired effect they will have to be large. While the schedule of the Kyoto Protocol may appear daunting, in the long term mere compliance with the protocol will hardly change the rate of increase of atmospheric CO 2. There are, however, technical, economical and practical choices that will allow the industry to meet the requirements of protocol and ultimately stop the increase in atmospheric CO 2 without eliminating coal from the fuel mix. In this paper, we present a review of current and emerging technologies for CO 2 sequestration. We provide a summary of the underlying scientific principles and discuss the practical and economic aspects of sequestration technologies, which will allow continuing use of global coal resources with minimum or no impact on CO 2 levels in the atmosphere.

Modeling Truck–Shovel Systems as Closed Queueing Network with Multiple Job Classes

Abstract In this paper an analytical method is proposed to model the truck-shovel system as a closed queueing network with multiple job classes. This approach would provide the capability of estimating system performance measures (mine throughput, mean number of trucks, mean waiting time etc.) for planning purposes when the truck fleet is not necessarily composed of identical trucks. A computational study is presented to show how choosing different types of trucks affect the production level in a truck-shovel system. Mean Value Analysis (MVA) approach is used to compute all performance measures of the truck-shovel system.

A framework for optimizing managerial decision

There have been numerous attempts to analyze and formulate management problems within the general framework of Management Science and Operations Research, so as to help managers in their decision making problems. This paper focuses on the fundamental aspects of management decision making and introduces a conceptual framework in which problems of management and its different levels of functioning are systematically identified. Management problems are considered within two major categories: Enterprise and Operations problems. In spite of the difficulties in defining a clear-cut boundary between Enterprise and Operations problems, such a broad classification leads to three basic levels of management functioning, namely: Policy making, coordinating and implementation. The universal relationship among these three basic levels of functioning provides a basic functional element called the Management Triad. In contrast to classical higherarchial structure, triad structure provides a methodology to analyze relationships among different levels of management functions in terms of a given decision problem. It is demonstrated that for different decision making problems individuals can shift from one end of the triad to another and perform a different management function. A quantitative approach has been introduced for operations management decision making by adapting Shewharts control chart philosophy which in turn provides for quasi-automated decisions for corrective action and also for filtering significant signals of change to appropriate management functioning levels.

A dynamic programming approach in designing underground coal slurry haulage systems

SummaryUnderground hydraulic haulage systems (UHHS) are emerging as an alternative to conventional systems with the potential of eliminating haulage bottlenecks, and health and safety hazards in underground coal mines. Currently, identified problems associated with the application of UHHS are: 1. the lack of engineering design data; 2. the need for new equipment development; 3. better instrumentation and control; and 4. the need for optimum design methodology.This paper deals with the fourth problem. A dynamic programming model has been developed to evaluate UHHS in different stages; starting from the coal faces up to a surge bin or to the preparation plant on the surface. Given a system layout and the number of faces, the model determines, at each stage, the equipment (pump-pipe combination) that minimizes the cost per tonne of coal handled. Equipment type, surge capacities, slurry characteristics, and local and cumulative costs are determined at each stage. The paper summarizes the approach, its limitations and underlying assumptions, and demonstrates the use of the model with a numerical example.

Future Zero Emission Carbon Technology—Valuation and Policy Issues

Today, coal-fired power plants produce about 51 percent of the total 3,883 billion kWh of the annual electrical energy output in the U.S. Demand for electricity is expected to grow in the future. Coal can and will continue to play a substantial role in the future global energy supply, despite its high emission of CO 2 and low thermal energy conversion efficiency of about 37 percent. This is due to the fact that it is inexpensive and global reserves are abundant. Furthermore, cost-competitive and environmentally acceptable energy alternatives are lacking. New technologies could also make coal-fired power plants more efficient and environmentally benign. One such technology is the zero emission coal (ZEC) power plant. How much will such a technology cost? How competitive will it be in the electric energy market when used as a technology for mitigating CO 2 emissions? If there were regulatory mechanisms such as a carbon tax to regulate CO 2 emission, what would the minimum carbon tax be that should be imposed? This article introduces an economic model that can be used to analyze and assess the economic viability of the ZEC technology vis-a-vis other competing energy generating technologies, e.g. conventional coal-fired, combined-cycle gas turbine, and nuclear power plants, using valuation techniques employed in the electric energy industry such as revenue requirement (e.g. cost-of-service).

Optimization of underground transportation systems using a network flows model

SummaryA new approach to optimization of underground transportation systems using a network flows model rather than simulation techniques applied to specific underground systems is presented. The model is illustrated using a sublevel caving system to demonstrate the stages used to obtain an optimum system cost.