ENHANCED STEAM CYCLE UTILIZING A DUAL PRESSURE RECOVERY BOILER WITH REHEAT

摘要

An enhanced steam cycle utilizing a dual pressure recovery boiler with reheat allows a large increase in electrical generation with various turbine cycles while overcoming traditional lower furnace material limitations. A dual pressure designed recovery boiler furnace is provided with a lower furnace and an upper furnace. The lower furnace is operated at a lower temperature to prevent or reduce corrosion of the lower furnace wall tubes caused by the reducing environment. The lower furnace can be either a low pressure natural circulation steam generating (drum) system or economizer. Unlike the lower furnace, the upper furnace is not exposed to a reducing environment and is therefore not as susceptible to severe corrosion rates. The upper furnace is operated at higher temperatures and pressures which permit implementation of higher efficiency reheat steam cycles. The upper furnace thus operates as a high pressure natural circulation steam generating (drum) system, or as a once- through supercritical steam generating system. The dual pressure recovery boiler can thus be coupled to a variety of condensing, non-condensing or a combination of condensing and non-condensing turbine cycles to provide a large increase in electrical generation.