Modern gas-turbine drives (GTD) have very strict requirements to air purity and resistance at the GTD gas-air flow duct inlet. The purity level of inlet air affects directly the GTD service life and wear rate of separate components. Old power plant modifications (the PAES-2500 family) are equipped with sound-attenuating systems without additional air-filtering devices, thus it is very often led to the GTD failure due to the wear of compressor and turbine rotor blades. The special combined air-filtering device (AFD) was developed in an attempt to increase the resource potential of GTDs used as a part of power plants.
The AFD operation concept means the subsequent reduction of inlet flow speed and the separation of pure air from dust, including the dust stream redirection to outside, reduction of air flow noise characteristics, and its supply to the GTD inlet. By reference to destination, the structural shape was identified and the prototype AFD was manufactured. Currently this prototype is passing through tests, as a part of the PAES 2500 gas turbine power plant, at the machine factory in Volochisk. Each AFD block is responsible for certain function:
- The protective visor (item 1) protects the AFD from atmospherical condensation (rain, snow, foliage, etc.), and ensures the required reduction of air flow speed so that the atmospherical condensation could not be sucked by engine from power plant surrounding areas. To prevent frost formation on the AFD surface, the protective visor is equipped with anti-icing system comprising infra-red heater which activates automatically (when the ambient temperature is +5°С) and switches OFF (when the ambient temperature is 10°С) or in a manual mode.
- The AFD block (item 2) is equipped with the QE0458 air-filtering system (Fig. 2) which was specially developed by Pall Company (Great Britain). The operation concept of this system is based on specially graded dimensions of multicyclone panel due to which the incoming pure air can be separated form dust when it is circulating along the centrifugal spiral channels. Further on the pure air flows in the direction of GTD, while dust accumulates in special collectors, where from it is removed by fan (item 6) through the dust-exhaust air duct (item 5).
- After cleaning the air is supplied to diffuser (item 5), then flows to the noise suppression device (item 4). This device is designed to reduce noise caused by the GTD operation and is a splitter silencer with two rows of silencing panels. Their dimensions and locations ensure the maximum efficient sound power reduction when there is a slight effect on resistance increase in the AFD gas-air flow duct.
- Further on the air is supplied from noise suppression device to the GTD inlet, however due to specially installed splitter plates the part of incoming air is used for generator cooling.
Due to the application of newly developed AFD system, the GTD lifetime, as a part of power plants, will be considerably increased; this can ensure smooth operation even in dusty areas.