tailieunhanh - Process Engineering Equipment Handbook Episode 3 Part 8

Tham khảo tài liệu 'process engineering equipment handbook episode 3 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | T-78 Turbines Steam Shaft gland seal ring Spring-loaded labyrinth-type gland seals are used to minimize air leakage into and steam leakage from the steam turbine. An automatic gland steam control system and condenser can be supplied. Bearing housings The bearing housings are of horizontally split design and are arranged for pressure lubrication of the bearings. Bearings can be inspected and serviced without removing the coupling hub or breaking the pressure-containing casing joint. Journal and thrust bearings Tilting-pad radial bearings provide optimum rotor stability at all operating loads by forming an oil wedge at each shoe. This design is very effective in damping vibrations and is far superior to sleeve-type radial bearings. Double-acting selfleveling thrust bearings are used providing maximum protection against process upsets. Optional turning gear prior to startup and shutdown for large bearing span rotors can be supplied for automatic or manual operation. Auxiliary Systems Microprocessor-based steam turbine governor control system The electrohydraulic control system automatically and continuously monitors and sets the steam turbine speed to satisfy customers specific requirements. Low maintenance operation typifies this type of system which also features solid-state electronics redundant speed pickups and signal processing channels to reduce problems ordinarily associated with mechanical controls. The result is improved reliability accuracy and overall enhanced steam turbine performance. Valve gear assembly The valve gear assembly controls the steam flow to the turbine. It utilizes a simple but rugged bar lift design for increased reliability. The individual valve spindles are designed with spherically seated nuts to compensate for any minor misalignment while reducing the possibility of valve spin. The contact surfaces of both the control valves and seats are stellited for increased life. Another major feature is the large springs that are designed to .