Life of steam turbine and optimum seeking method of high pressure feedwater heater starting with it together

摘要

This article describes an optimum seeking method of high pressure heater with steam turbine unit on starting together. How will mis method influence turbine casing? How will this operating method raise economy, safety, reliablility and flexibility of this unit? When high pressure heater of optimum seeking operating is utilized to start with steam turbine together on this foundation of the designing life of high pressure heater and steam turbine unit ensured. It's well known that bom high pressure heater equipment and system designed are perfected day by day. It is truth that operating program of high pressure heater is more and more increasing. Though all different sorts of operating method of high pressure heater started with the unit is better than that of high pressure heater started under high electric load. But Some of high pressure heater starting does not adopt to coast up parameter-include pressure and temperature-slowly with turbine unit starting together, It is started up after electric load synchronized in the system, by-pass steam cut or load of 20-30MW starting, It is worse than sliding parameter starting with turbine unit together at all. It is not stated in the paper of national or international while the high pressure heater would be put into with turbine unit starting at a period of 125MW, 200MW and 300MW turbine unit starting or running that mermodynamics system have been designed? Is it being started before or after turbine starting and during starting, speed-up or warming turbine? How is this method? How is the starting situation? Is it simple and convenient method, or easy to operate? What effect is it for expansion difference of turbine casing? So we chose several reasonable operating scheme and compared with these plan, It gave us a optimum seeking starting scheme with steam turbine unit starting together, It has several advantage about the scheme that has been carried out for starting steam turbine unit during me unit running. 1. Both steam turbine casing and high pressure heater are being prewarmed together at the same time before turbine starting, for utilizing optimum seeking method of high pressure heater. So both of temperature gradient and thermal stresses are decreased at a period of starting up, It will postpone the using life of both. 2. This program is easy to operate, this workloads of operating worker will be reduced when operating worker use this plan. 3. High pressure heater starting will be adjusted with turbine unit prewarm steam and shaft sealing steam together at the same time when this thermal power system of the unit designed is started up for this starting system of medium pressure casing. It will reduce this time of warming turbine casing and ensure the stress of turbine casing and shaft. Every direction temperature of the unit casing and shaft are more average, and It is fast to start, to synchronize in the system, to raise electric load, It is economy and flexibility for all of starting and raising load course.