Abstract: | Using steady-state simulation, we have evaluated the effect of boiler superheat and reheat temperatures on the economics of the utility section of a Bayer Alumina Plant. These economics were compared with those of a steam plant which purchased power. Under this study's nominal economic conditions, producing steam and purchasing electricity was the cheaper option. A sensitivity analysis showed that the cogeneration plant became the better choice when the local cost of electricity rose above 10C/kWh. The plant economics improved monotonically with superheat temperature as did the thermo-dynamic efficiency. However, for reheat, the plant economics did not improve monotonically with temperature even though the thermodynamic eficiency did; thus improvement in the thermodynamic efficiency does not always yield improved economics. |