English Subtitles for GE Gas Turbine Basic Cycle

Subtitles / Closed Captions - English

a gas turbines operates by drawing in fresh air

then compressing it to a higher pressure through its axial flow compressor next fuel is added to the compressed air and burned which raises the energy level this high-pressure high-temperature air is then sent to an expansion turban where the gas energy is converted to the mechanical energy of a rotating shaft the conversion of work in the turban actually takes place in two steps in the

nozzle section of the turban the hot gases are expanded and a portion of the thermal energy is converted into kinetic energy in the subsequent bucket section of the turban a portion of the kinetic energy is transferred to the rotating buckets and convert it to work typically more than fifty percent of the work developed by the turban section is used to power the axial flow compressor since the gas turbines is an ambient air

breathing machine its performance will be changed by anything affecting the mass flow of the air intake to the compressor the most obvious are changes in the reference conditions of 59 degrees Fahrenheit and 14.7 PSI a depending on the unit cycle parameters and component efficiencies ambient temperature will affect the air mass flow which in turn will change output eat consumption heat rate and exhaust flow

when burning lower heating value fuels turban mass flow is increased because more fuel and air are required this drives up the compressor pressure ratio eventually encroaching on the compressor surge limit this means that such a large volume of fuel is required to fire the machine that it begins to push back on the compressor discharge pressure causing a

reverse flow to occur in the compressor the compressor rotor is assembled by vertically stacking the wheels first the compressor forward stub shaft and first wheel are put into the stacking fit with ty bolts in place then each wheel is slid vertically over the thai bolts in the case of the MS 7,000 da there are a total of 17 wheels on the compressor rotor

once the last wheel and after stub shaft are stacked the thai bolts are then torque once the compressor rotor is assembled it is slow speed balance to make sure vibration levels meet design standards ge is a leader in rotating equipment and vibration analysis also filled and service shop balancing can be done after the unit is in service

the first step of the assembly of installing the first stage buckets to the turban wheel is to insert the radio locking pin into the locking bucket dovetail the first bucket is installed in the counterclockwise adjoining dovetail slot and is held in place with a deaky the remainder of the buckets are installed in this fashion working around the wheel counterclockwise

the last bucket is installed into its dovetail and the axial locking pin is driven into the wheel this pushes the radial locking pin up to hold the last bucket in place all the buckets are now locked onto the turban wheel before the second and third stage buckets are installed twist locks are put in place then the buckets are installed as a 360 degree ring the ring is worked into the wheel gradually due

to the interlocking z lock once they're installed the twist locks are rotated to lock them in place ge is a leader in rotating equipment and vibration analysis once the casings are on the combustion system is installed next the shell cooling air piping is installed here comes from off base blowers to facilitate shell cooling in the turban and exhaust casings

then the inlet plenum is installed after this the exhaust plenum is put in place the Flex seals keep the exhaust gases from escaping into the turban compartment or out to atmosphere while allowing for thermal expansion finally the compressor bleed valves are installed these are operational during startup and shutdown to protect the unit from Serge the number one bearing is installed in the inlet casing and the number two and

number three bearings and housings are placed into their respective casings the lower half is put in first then the upper half of the bearings and housings are installed then the bearings are aligned with the casings installed the upper half of the bearing housings and casings are then removed and the air seals and oil deflectors are installed the final step is the installation of the rotor and the upper halves of the

bearing housings and casings to assemble the first stage Russell the nozzle segments are installed into the support ring seals are installed to minimize gas leakage alignment pins are then installed two radially align the segments in the ring to assemble the second stage nozzle first a core plug is installed in the

investment cast piece to allow for even cooling down the center of the bore of the nozzle segment the diaphragm section is then attached and a pin is installed for nozzle to diaphragm alignment wheel spaced cooling tubes and plugs are installed in the diaphragm the third stage nozzle is similar to the second stage nozzle but it is not forced air cool so there is no core plug and there are no cooling

tubes the Assembly of the combustion system begins with the transition piece bolted to the first stage nozzle on its aft end and supported by the bullhorn bracket on its forward end next the combustion casing is bolted onto the combustion rapper then the flow sleeve slides into the casing the cross fire tubes are then installed but pushed out of the way so that the liner may be installed once it

is the cross fire tubes are put into the crossfire tube collars in the liner retaining clips keep the cross fire tubes in place next the combustion can cover is bolted onto the combustion casing and then the fuel nozzle is installed onto the combustion can cover spark plugs and flame detectors are also installed on certain combustion cans depending on the vintage of the unit

as you know the upper halves of the casing removed to allow for internal component installation all vertical and horizontal bolts are removed and the casings are lifted off one at a time in the following sequence first the turban shell then the compressor casing then the inlet casing then the exhaust casing and finally the compressor

discharge casing to give you a mechanical analogy check valves behave the same way as diodes in electrical systems in this analogy a fixed pressure to the main manifold is provided by the supply tank the pressure at the main manifold can be regulated by the check valves a B or C for example the pressure at point one is considered constant at 20

psi if the pressure at points 2 3 & 4 are higher than 20 psi then there will be no control of the pressure at the main manifold if the pressure at point two decreases - 18 psi and the pressure at point three and four remain the same then the pressure at the manifold will be brought down to 18 psi and system a

is controlling as the operating conditions change the pressure requirements at points3 and for a change as the pressure say at point three drops below 18 PSI for example 17 PSI the manifold pressure will be brought down to 17 PSI causing check valves a and C too close and check valve be to open therefore system B is now controlling

the startup control loop controls the rate of fuel edition for several reasons to establish flame in the combustors to control the acceleration rate and to control the rate of temperature change acceleration of the turbine rotor must be controlled so as not to exceed the allowable forces on the rotor exceeding the limit can cause heavy damage to the rotor during startup the air flow rates are low

if there is too much fuel added to the combustors while there isn't enough air temperatures could get dangerously high potentially damaging internal hardware and high fluctuations in temperature can reduce the life of the internal hardware different materials heat at different rates so the rate of temperature change must be limited at approximately five degrees

per second the electronic / speed protection function is performed as shown here the turban speed signal derived from the magnetic pickup sensors is compared to an overspeed set . when the turban speed signal exceeds the set . the overspeed trip signal is transmitted to the master protective circuit to shut down the turban and electrical / speed trip message will be displayed

the fuel gas pressure transducer has a DC voltage output directly proportional to pressure input in PSIG this transducer provides the control system with a feedback signal for the operational fuel gas pressure or p2 pressure between the stop speed ratio and gas control valves the fuel gas vent solenoid valve fence the volume between the stop speed ratio valve and the gas control valve when the solid Lloyd is de-energized this valve is closed during

operation when it is open it ensures that during the shutdown . fuel gas pressure will not build up between the stop speed ratio valve and that no fuel gas will leak past the clothes gas control valve new selecting any button will show information about its function the help menu button will return you to the screen when you are finished the

exit help button will return you to the course this yellow band is the button highlight it is used to recommend a logical path through the course the suggested path is highly recommended for first time users between which two points in the Brayton cycle is the pressure constant and the volume of the hot gases increasing sorry your choice is incorrect

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