1. Outer Combustion Chambers and Flow Sleeves
The outer combustion chambers act as the pressure shells for the combustors. They also provide flanges for the fuel nozzle-end cover assemblies, crossfire tube flanges, spark plugs, flame detectors and false start drains as shown in figure (3.19). The flow sleeves form an annular space around the cap and liner assemblies that directs the combustion and cooling air flows into the reaction region.
2. Crossfire Tubes
All combustion chambers are interconnected by means of crossfire tubes. The outer chambers are connected with an outer crossfire tube and the combustion liner primary zones are connected by the inner crossfire tubes as shown in Fig.(3.20)
3. Fuel Nozzle End Covers
There are five fuel nozzle assemblies in each combustor. Fuel nozzle has five tube as liquid fuel tube, water tube, atomizing air tube, diffusion gas tube and premix gas tube as shown in Figure (3.21).
The nozzle shown is for the dual fuel option and shows the passages for diffusion gas, premixed gas, liquid fuel, atomizing air and water. When mounted on the end cover as shown in Figure (3.23). the diffusion passages of the five fuel nozzles are fed from a common manifold, called the primary that is built into the end cover. The premixed passages of the same four nozzles are fed from another internal manifold called the secondary. The premixed passages of the remaining nozzle are supplied by the tertiary fuel system. The diffusion passage of that nozzle is always purged with compressor discharge air and passes no fuel when operate at gas fuel.
4. Liner and Cap Assemblies
The combustion liner shows in Figure (3.24). Figure (3.25) shows combustion liner use external ridges and conventional cooling slots for cooling. Interior surfaces of the liner and the cap are thermal barrier coated to reduce metal temperatures and thermal gradients.
The cap shows in Figure (3.26) has five premier tubes that engage each of the five fuel nozzle. It is cooled by a combination of film cooling and impingement cooling and has thermal barrier coating on the inner surfaces.
5. Spark Plugs
Combustion is initiated by means of the discharge from spark plugs which are bolted to flanges on the combustion cans and centered within the liner and flow sleeve in adjacent combustion chambers 2 and 3. A typical spark plug arrangement is shown in Figures(3.27) and (3.28) .These plugs receive their energy from high energy-capacitor discharge power supplies. At the time of firing, a spark at one or more of these plugs ignites the gases in a chamber. The remaining chambers are ignited by crossfire through the tubes that interconnect the reaction zone of the remaining chambers
.
6. Ultraviolet Flame Detectors
During the starting sequence, it is essential that an indication of the presence or absence of flame be transmitted to the control system. For this reason aflame monitoring system is used consisting of multiple flame detectors located at combustors 15, 16,17and 18 as shown on Figure (3.29). Have water cooled jackets to maintain acceptable temperatures. The ultraviolet flame sensor contains a gas filled detector. The gas within this detector is sensitive to the presence of ultraviolet radiation which is emitted by a hydrocarbon flame. A DC voltage, supplied by the amplifier, is impressed across the detector terminals. If flame is present, the ionization of the gas in the detector allows conduction in the circuit which activates the electronics to give an output indicating flame. Conversely, the absence of flame will generate an output indicating no flame. The signals from the four flame detectors are sent to the control system which uses an internal logic system to determine whether a flame or loss of flame condition exists.
7. DLN 2 System Operation.
General DLN-2 control system regulates the distribution of fuel delivered to a multi-nozzle combustor arrangement. The fuel flow distribution to each combustion chamber fuel nozzle assembly is a function of combustion reference temperature and IGV temperature control mode. Diffusion, piloted premix and premix flame are established by changing the fuel flow distribution in the combustor. By a combination of fuel staging and shifting of burning modes from diffusion at ignition through full premix at high load, dramatically lower NOx emissions can be achieved above firing temperatures of 2270 oF.
The outer combustion chambers act as the pressure shells for the combustors. They also provide flanges for the fuel nozzle-end cover assemblies, crossfire tube flanges, spark plugs, flame detectors and false start drains as shown in figure (3.19). The flow sleeves form an annular space around the cap and liner assemblies that directs the combustion and cooling air flows into the reaction region.
2. Crossfire Tubes
All combustion chambers are interconnected by means of crossfire tubes. The outer chambers are connected with an outer crossfire tube and the combustion liner primary zones are connected by the inner crossfire tubes as shown in Fig.(3.20)
3. Fuel Nozzle End Covers
There are five fuel nozzle assemblies in each combustor. Fuel nozzle has five tube as liquid fuel tube, water tube, atomizing air tube, diffusion gas tube and premix gas tube as shown in Figure (3.21).
The nozzle shown is for the dual fuel option and shows the passages for diffusion gas, premixed gas, liquid fuel, atomizing air and water. When mounted on the end cover as shown in Figure (3.23). the diffusion passages of the five fuel nozzles are fed from a common manifold, called the primary that is built into the end cover. The premixed passages of the same four nozzles are fed from another internal manifold called the secondary. The premixed passages of the remaining nozzle are supplied by the tertiary fuel system. The diffusion passage of that nozzle is always purged with compressor discharge air and passes no fuel when operate at gas fuel.
4. Liner and Cap Assemblies
The combustion liner shows in Figure (3.24). Figure (3.25) shows combustion liner use external ridges and conventional cooling slots for cooling. Interior surfaces of the liner and the cap are thermal barrier coated to reduce metal temperatures and thermal gradients.
The cap shows in Figure (3.26) has five premier tubes that engage each of the five fuel nozzle. It is cooled by a combination of film cooling and impingement cooling and has thermal barrier coating on the inner surfaces.
5. Spark Plugs
Combustion is initiated by means of the discharge from spark plugs which are bolted to flanges on the combustion cans and centered within the liner and flow sleeve in adjacent combustion chambers 2 and 3. A typical spark plug arrangement is shown in Figures(3.27) and (3.28) .These plugs receive their energy from high energy-capacitor discharge power supplies. At the time of firing, a spark at one or more of these plugs ignites the gases in a chamber. The remaining chambers are ignited by crossfire through the tubes that interconnect the reaction zone of the remaining chambers
.
6. Ultraviolet Flame Detectors
During the starting sequence, it is essential that an indication of the presence or absence of flame be transmitted to the control system. For this reason aflame monitoring system is used consisting of multiple flame detectors located at combustors 15, 16,17and 18 as shown on Figure (3.29). Have water cooled jackets to maintain acceptable temperatures. The ultraviolet flame sensor contains a gas filled detector. The gas within this detector is sensitive to the presence of ultraviolet radiation which is emitted by a hydrocarbon flame. A DC voltage, supplied by the amplifier, is impressed across the detector terminals. If flame is present, the ionization of the gas in the detector allows conduction in the circuit which activates the electronics to give an output indicating flame. Conversely, the absence of flame will generate an output indicating no flame. The signals from the four flame detectors are sent to the control system which uses an internal logic system to determine whether a flame or loss of flame condition exists.
7. DLN 2 System Operation.
General DLN-2 control system regulates the distribution of fuel delivered to a multi-nozzle combustor arrangement. The fuel flow distribution to each combustion chamber fuel nozzle assembly is a function of combustion reference temperature and IGV temperature control mode. Diffusion, piloted premix and premix flame are established by changing the fuel flow distribution in the combustor. By a combination of fuel staging and shifting of burning modes from diffusion at ignition through full premix at high load, dramatically lower NOx emissions can be achieved above firing temperatures of 2270 oF.
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