Enhancement of energy efficiency and loading of steam turbines through retrofitting 2-d designs with 3-d designs

摘要

This paper presents improvement in energy efficiency and power loading of steam turbines through module retrofits accomplished by migration from 2-d designs to 3-d designs. Isentropic efficiencies (IE) (average and operating, respectively) of high pressure turbine (HPT), intermediate pressure turbine (IPT), low pressure turbine( LPT) and composite turbine (CT) of original 2-d design of machines (100% MCR) (reference level) are: 82.91, 79.40%; 89.93, 86.60%; 82.48, 79.24%; and 86.15, 81.86%. Design IE of turbine can be increased to 90.04% for HPT, 92.04% for IPT, 94.01% for LPT and 92% for CT by retrofitting with standard 3-d stage specific blading, 3-d modelled exhaust diffuser, tip to tip sealing of improved design, etc. Power output of overall turbine is expected to increase by ～14 MW (for original steam flow) or heat rate is expected to decrease by 6.6% (through reduced steam consumption). Operating turbine efficiency is expected to increase from 39.90% to 42.72%. The 3-d stack optimized design is expected to give an improvement of 6-7% over 2-d design. Loading of unit can be enhanced without any major hardware changes with a few improvements in boiler and generator and these will not limit unit loading.