Industrial Cogeneration Design Options

Cogeneration in process industries with high energy demand provides an opportunity to cut energy costs and increase revenues. A study funded by the Electric Power Research Insitute (EPRI) of a hypothetical 1985 1000 ton per day kraft pulp mill evaluates steam and power system design options for three cases, compares the economics, and looks at ownership and operating alternatives. The first case is the no generation case. Steam is produced for process use, and electric power is purchased but not generated. The second is the thermal match case. Steam needed for process is produced at a higher pressure and temperature and then passed through a turbine to generate electric power before being used to meet the plant's thermal demands. In the third case, the maximum cogeneration case, more steam is generated than the plant requires. The additional steam is used to generate additional power. The plant may buy all of its electric power from the utility while selling over separately metered tie lines all of the power generated, or the plant may sell only surplus power available after meeting its own power needs.