A geothermal turbine comprises a turbine casing, a turbine rotor shaft, a plurality of nozzle diaphragm outer rings fixed to the turbine casing, a plurality of nozzle diaphragm inner rings located radially inside the nozzle diaphragm outer rings, a plurality of nozzles placed between the nozzle diaphragm outer rings and the nozzle diaphragm inner rings, which form a steam passage, a plurality of rotor blades mounted on the turbine rotor shaft, which face the nozzles and form a blade cascade in a circumferential direction, a shroud arranged on tip of the rotor blade, an overhang attached to the nozzle diaphragm outer ring, which extends downstream of the nozzles and has an inner surface facing radially outside the shroud, and a plurality of sealing fins which protrude radially outward from the shroud and face the overhang.
A drum-type rotor carries an annular row of moving blades having root portions held within a slot in the periphery of the rotor. A turbine casing surrounds the rotor and carries a static blade assembly with an annular row of static blades which, together with the annular row of moving blades, constitutes an impulse turbine stage. The static blade assembly has a radially inner static ring confronting a periphery of the rotor with a seal acting therebetween. The static blade assembly has an outer static ring which has a substantially greater thermal inertia and stiffness then the inner static ring and is capable of sufficient radial sliding relative to the casing so as to accommodate relative thermal expansion and contraction of the outer static ring and the turbine casing.
A direct contact steam injection heater is placed directly in line with a flow of stock through a pipe. The steam injection heater includes a Mach diffuser having a plurality of steam diffusion holes and an adjustable steam-plug cover that is positioned within a stationary diffuser tube to modulate the amount of steam added to the flowing stock by exposing a desired number of steam diffusion holes. The steam tube assembly includes an O-ring that forms a seal along the inner wall of the diffuser tube to prevent the flow of stock into the steam tube assembly when steam pressure is not present. Select areas of the steam injection heater, including the deflection plate, diffuser tube and heater body inner wall are coated with a wear coating such as tungsten carbide. Further, a pair of pressure ports are formed in the steam-plug cover to equalize the pressure between the open interior of the steam-plug cover to further facilitate rotation of the steam-plug cover.
