Journal of Energy Engineering

A 1,200 tons‐per‐day waste‐to‐energy facility has been constructed in Minneapolis, Minnesota, and has been in operation since October 1989. Trucks deliver municipal solid waste (MSW) to the facility, are weighed, then discharge their loads into the seven‐day capacity refuse bunker. Two manually operated cranes mix and charge the refuse into two furnace feed hoppers. The turbine generator is capable of producing approximately 38.12 MW when the plant is burning 1,212 tons per day of “design” waste. The facility consists of two identical processing trains, each capable of burning 606 tons of MSW per day. Each of the two process trains includes a combustion air system, a grate system, a boiler, and atomizing spray dryer, a baghouse, an induced draft fan, a stack flue and, other auxiliary equipment. A distributed digital control system provides for single operator plant control. The paper describes each of the major plant systems, the plant performance design data and some of the design philosophies that governed the plant design.

An inflated fabric cooling dome is evaluated as an alternative to forced draft wet cooling towers for power plants. It consists of a central standpipe through which the hot water flows onto the surface of an inflated circular needle‐punched fabric dome, then radially to a collection trough at the perimeter of the dome as it is cooled by air which flows outward through the fabric. A bench model is used to evaluate economic air and water flow rates and thickness of fabric used as the heat exchange material. Parametric studies include effects of land cost, rate of return, fuel inflation rate, and replacement frequency of fabric dome and fans.

A chronological approach to scheduling a pumped‐storage plant optimally using an hourly time step is discussed. An objective function defines total power cost for any hour as a function of system generation; the pumped‐storage plant adds cost for any pumping hour and reduces cost for any generating hour. Hourly conservative‐of‐flow equations, coupled with lower and upper limits on the plant's storage, constrain the reservoir's hourly storages. Unit pumping and generating capabilities are nonlinear functions of the plant's head and are included here as nonlinear upper bounds on hourly generation or pumping. An existing nonlinear programming package optimizes the objective function while satisfying the constraint equations. An application to a large pumped‐storage plant that is part of a large power system is given for a weekly planning period. This approach requires only a minimum programming effort, even for a problem with hundreds or thousands of constraint equations, and is implemented on an enhanced personal computer.