Abstract
A novel combined vapour compression/multi-effect boiling waste heat recovery system suitable for variable temperature energy sources is presented. The multi-effect boiling system comprises 14 vertical tube evaportor effects with an extended evaporation range from 114°C to 36°C and operates in the vapour compression mode. The vapour is compressed using a LiBr—water absorption machine fired by the exhaust of a gas turbine. The absorber receives the vapour produced in the last effect of the multi-effect boiling system while the top effect receives the steam produced in the generator of the absorption machine.
Analysis of the combined system shows its operational felxibility compared to other waste heat recovery systems. Using the exhaust of a GE-32670 kW gas turbine, the proposed combination would produce up to 3.44 mgd of fresh water at a performance ratio of 10 and a product rate of 4.3 gal/kWh. This is 44% higher than that of existing waste heat recovery distillation systems, with no expense for extra firing.