my LP turbine differential expansion increase ,when rated gland steam temperature maintain.
cold start up of a steam turbine has to be done after a rather long period of shut down - when turbine case and chest temperature are fallen down dramatically. turbine constructor heating ramps mast be followed in order to avoid thermal stresses on the metal of turbine case , valve case and rotor to avoid also height differential expansion between rotor and case that could lead to contact between case and rotor because of the different thermal inertia of the two parts.when the heating is complited the turbine can be started checking closely the differntial expansion recorders.when at speed the unit can be sincronyzed (usually at 3000 rpm) and then loaded according to the related load ramp.(megawatts\ minute)
Interlock system is in turbine for protect the turbine. different types of interlocks in turbine 1. high vibration, 2. Bearing oil Temp,3. vacuum related, 4. over speed, 5. differential expansion, 6. casing expansion, 7. lube oil header Pressure. 8. Axil shift. etc... . this interlocks is keep the turbine in safe mode in any abnormalities.
HP Turbine is High Performance Turbine LP Turbine is Low Performance Turbine
1. Low vacuum at high loads 2. High HRH temp 3.High steam flow 4. high gland steam temperature
casing and shaft are made of alloy steel they are supposed to expand when heated (at/2 *length of turbine.).wherea is coefficient expansion of material.t=finaltemperature ( of casing or shat)-ambienttemperaturel=length of turbine in meter
differential expansion is refer to differential distance between rotor blade and fix blade.rotor expand toward generator and casing expand toward control valve.when temperature increase ,expansion in casing and rotor.so rotor mass is less than casing which rotor expand more than casing.
Differential expansion means gap between fixed Blade & rotating blase of a turbine.. When steam enters into the turbine, rotor tends to expand towards generator side & casing tends to expand towards control valve side. If differential expansion increase then there is a possibility of reducing axial gap between rotor & fixed blades. When differential expansion is positive its means rotor expand more than the casing expansion. There is a limit upto +ve 5. If increases than +ve 5 it means we have to check front side tie rods status.
Turbine diff expansion can be positive or negative and depends on the convention used. The usual convention is that positive expansion is rotor expanding faster (hotter) than fixed components. Expansion is dictated by steam flow, gland steam temperatures etc
by controlling main steam flow
cold start up of a steam turbine has to be done after a rather long period of shut down - when turbine case and chest temperature are fallen down dramatically. turbine constructor heating ramps mast be followed in order to avoid thermal stresses on the metal of turbine case , valve case and rotor to avoid also height differential expansion between rotor and case that could lead to contact between case and rotor because of the different thermal inertia of the two parts.when the heating is complited the turbine can be started checking closely the differntial expansion recorders.when at speed the unit can be sincronyzed (usually at 3000 rpm) and then loaded according to the related load ramp.(megawatts\ minute)
gas turbine are used for expansion of high pressure gas,which rotates the rotor coupled with generator and hence electricity is finally produced.Gas turbine operate on brayton cycle.
Interlock system is in turbine for protect the turbine. different types of interlocks in turbine 1. high vibration, 2. Bearing oil Temp,3. vacuum related, 4. over speed, 5. differential expansion, 6. casing expansion, 7. lube oil header Pressure. 8. Axil shift. etc... . this interlocks is keep the turbine in safe mode in any abnormalities.
ROTOR ROTOR
multistage is used because the expansion of high pressure steam will be gradual and as a result the rotor wont vibrate.suppose we have only 1 stage of blades in a turbine, hence all the steam will expand in the given stage and the speed of the rotor will be in high range around 30,000m/s, which is very difficult to control and operate the turbine.
axial shift of a steam turbine is the shifting of turbine rotor in the forward and backward direction due to steam thrust on blades of rotor.
HP Turbine is High Performance Turbine LP Turbine is Low Performance Turbine
The difference in expansion of two objects having different length and heated in same temperature difference is called differential expansion.