Experience of reconstructing and converting aging condensing steam turbines for industrial and heating steam applications

摘要

Life extension for aging power plant steam turbines usually includes reconstructive measures intended not only to prolong their service tiem and raise their reliability but also to improve their efficiency. An effective way to solve this problem and simultaneously cover the needs in steam for heating and/or industrial purposes is the reconstruction and transformation of condensing steam turbines into cogeneration units with considerable steam extraction capability. this kind of reconstruction seems to be especially important in connection with the process of deregulation in the power industry and forming independent power (and steam or heat) suppliers. Different design decisions pursuing this goal have been developed and carried into effect at numerous power plants of the former Soviet Union as applied to over 360 steam turbines of different types with the single capacity of up to 200 MW. In so doing, their lifetime limits were extended far beyond the initial values. As a rule, the turbine reconstruction involves the turbine's governing system, some steam path component,s some auxiliaries, etc. Sometimes, it requires alterations of the turbine casings, bearings, and couplings. Usually, the reconstruction expenditures do not exceed a few percents of the total cost for a major overhaul and are repaid withi ntwo-to-three years.