Gas turbine total energy vapour compression desalination system

Various arrangements for heat recovery systems (HRS) are investigated for using the waste energy of a gas turbine (GT) engine driven sea water desalination plant, and the outcomes are compared with a basic sea water reverse osmosis (SWRO) plant. These arrangements are analyzed, and their flow diagrams are presented. The analysis showed that using a mechanical vapour compression (MVC) unit driven by the engine and utilizing its exhaust to fire two LiBr-H2O absorption cycle subsystems, in an all evaporation distillation system, yields a significantly improved plant performance compared to the basic one. The first absorption cycle operates in parallel with the MVC unit to fire a multiple effect stack (MES-I) with an evaporation range (ER) of 117-69 degrees C across 17 effects. The second cycle, however, works across a 19 effects low temperature MES-II with an ER of 66-6 degrees C with its bottom effect being connected to a common absorber for the two cycles. Compared with the SWRO system alone, using a 5.72 MW GT engine, the proposed arrangement increases the production by 72.4 percent from 2.9 to 5 mgd of potable water in addition to the 138.2 m(3)/d of heating steam condensate. This increases the performance ratio (PR) from 15.2 to 26.2 and, thus, reduces the power requirements from 12.5 to 7.27 kWh/m(3) of potable water. This is equivalent to an increase of 21.2 points for the GT thermal efficiency. Moreover, the system contributes a 1000 TR (ton refrigeration) cooling to the A/C units, as a by-product, which saves 1029 kW of equivalent power. Thus, the overall thermal efficiency is boosted by 26.5 points, which is equivalent to an annual savings of 11094 tons of Diesel fuel. (C) 1999 Elsevier Science Ltd. All rights reserved.