Research And Application Of Overall Optimization And Energy Saving Of The Supercritical600MW Steam Turbine Unit Imported By Westinghouse

"Energy-saving and emission-reduction" is one of China’s three basic national policy. China Huadian Corporation, one of five major power generation groups in China, makes it’s all coal-fired units upgraded and transformed comprehensively through units overall optimization". To take advantage of this opportunity, according to Westinghouse imported supercritical unit’s long-term equipment operating experience,we put forward series of feasible technology schemes by data tracking, energy analysis and program evaluation. And carry them out by the opportunity of#1unit’s overhaul. With careful operation and maintenance, making a long period safe and stable operation, the units energy consumption can achieve leader level to the same type units.Under the research on the same type units, comprehensive analysis of the units’ energy consumption parameters by thermodynamic test, sixteen technological transformations and fine repairs are carried out.Steam turbine:By opening the cylinder to increase efficiency and transforming of steam sealing, the high-heat exhaustion problem is solve; By turning medium pressure rotor shroudto reduce the medium pressure tip leakage loss; By welding Longmen milling to low pressure inner cylinder’s upper half part, opposite grinding and adding seal groove opposite to low pressure inner cylinder’s lower half part to reducing low pressure surface leakage; By shrinking HMP cylinder’s end seal clearance and the introduction of flexible seal to achieve the unit’s shaft end sealing; By introducing the concept of fuzzy system during the maintenance process to ensure accurate clearance adjustment and shafting stability.Steam turbine cold source:improve the efficiency of cooling tower through retrofit ting rotating nozzle and packing arrangement; improve condenser double pressure diffe rential pressure through rearranging air extraction pipes of condenser; retrofitting feed- water atomization nozzle in condenser to achieve mixing heat transfer of replenishmen t and exhaust steam, improve condenser pressure and guarantee the dissolved oxygen o f condensate.The optimization of thermodynamic system:By removing the redundancy and hydrophobic merging to reduce the valve leakage; By the transformation of high exhaust ventilation valve to reduce high exhaust steam loss; optimize boiler hydrodynamic structure and reduce heat loss of boiler under low load e missions by transforming the discharge valve from boiler steam-water separator to the condenser; reduce leakage loss and cavitation damage by optimizing the body structure of steam feed pump minimum flow valve.Safety index:By changing the type of septum valve seat to solving the problem of v alve seat diffuser hot loosing and improving safe reliability of preventing overspeed of steam; by transforming the connection type of septum valve rod to resolving the pro blem of rod hot bite and improving the safe reliability of preventing steam overspeed; by reforming turbin thrust tile structure to reduce temperature of bearing bush and im prove safe reliabilityof preventing rubbing movement; by transforming lubricating oil filtering system from coalescence type to vacuum type, improving security level of p rotective medium and safe reliability of bearings wear and low oil pressure protection.After the above sixteen technical transformation and fine repair, heat consumption of steam turbine is only50kJ/kWh higher than the design value, double back pressure of condenser and efficiency of cooling tower is higher than the design value. The coal consumption of two commonly used conditions reduces more than12g/kWh after the overall optimization of steam turbine, and unit economic indicators have reached the leading level of similar type units.