Research On Steam Turbine Shaft Seal Energy Saving Reconstruction Of 600MW Supercritical Unit

With the further development of energy saving and consumption reduction worldwide and the development of steam turbine technology,there are many new types of steam seal technology developed and utilized at present.The design and manufacturing technology of steam turbine flow passage is becoming more and more perfect,and the loss of steam leakage has become one of the important factors restricting the improvement of steam turbine efficiency.Different types of steam seals can be used to solve some shortcomings of traditional steam seals.Under certain conditions,smaller steam leakage can be effectively maintained.In view of the specific problems of the unit,it is easier to ensure a good state of the unit by choosing a suitable new type of steam seal,which can play a significant role in maintaining or improving the economic performance of the unit.However,the traditional steam seal can not be blindly negated,and it can reach a fairly high economic level after careful adjustment.If the new type of steam seal can not adapt to the structure and performance characteristics of the unit,it is possible to reduce the seal clearance if the steam seal is not reformed.As with any technology,the application of new type steam seal is affected by many factors(with specific issues,the units themselves have seal design manufacture and installation quality),needs to be taken seriously in all aspects,in order to play its due role.The traditional labyrinth seal(also known as the stepped labyrinth seal,labyrinth)using a series of gap between gland teeth which are arranged with the shaft smaller,forming a small steam chamber,the high-pressure steam in the steam chamber gradually reduced pressure,to achieve the purpose of reducing leakage of steam.Because of its simple structure and strong adaptability,comb seal has been the most widely used non contact seal in the steam turbine since its development.At present,steam turbine manufacturers have almost all of the steam seals that come into the factory when they leave the factory.However,in actual operation,because the steam spring seal block in high temperature and high pressure,poor working environment,the reason coupled with the spring piece of material itself,in the maintenance of turbine often found due to a spring elastic sealing block is bad,fouling caused by death card,seal clearance changes.Unable to reach the seal design gap,resulting in a decline in the performance of steam seal.Especially in the steam turbine start stop process,because the cylinder inside and outside the nonuniform heating and deformation,and the critical speed of the rotor of large amplitude,may cause the rotor and steam seal tooth local friction,resulting in steam seal tooth wear,seal gap increases,the leakage rate increase,decrease the efficiency of steam turbine.Therefore,with the increase of running time and the number of starting and stopping times,the traditional comb seal often suffers from the wear of the steam seal teeth,the large gap between the actual steam seal and the decrease of the sealing performance,resulting in the decrease of the economic performance of the unit.In addition,the steam seal is in the working state due to the limitation of the structure characteristics of the comb seal,and there is circumferential flow in the steam seal cavity,which is easy to cause airflow vibration and induce low frequency vibration of the unit,thus affecting the safe operation of the unit.With the development of technology,a variety of new steam seals have appeared.By improving the design,all kinds of new type steam seal can often without affecting the safe operation of the unit,run in the seal gap smaller,thereby reducing the leakage of steam,the economy of the unit operation is improved.Due to the small investment and quick profit of steam seal retrofit,more and more power generation enterprises adopt new steam seals with better performance to improve the performance of the original steam seal.