My little views on Gas Turbines!


The characteristic features that comes to the mind when one speaks of the gas turbines are the compression and the heat addition (Combustion) process.
The gas turbines perhaps represents the most satisfactory way of producing large amount of power in a self-contained and compact unit.
The conjuncture of the gas turbines and the petrol engines may be possible in the future.
 However, in smaller gas turbines the inefficiencies in compressions and expansions are great. So, to overcome this there is a need of using a heat exchanger.
 To make it economical, a compact effective heat exchanger must be used in the gas turbine cycle.
 When compared to the Steam Turbines, the Gas Turbines have a modest   20-30% thermal efficiency. The latter has about 38-40% thermal efficiency.
The applications of the Gas Turbines are in the fields of:
1. Aviation                             2. Power generation
3. Oil and Gas industries         4. Marine Propulsion
A Gas Turbine is a self-contained, light weight not requiring any cooling water and generally fit in the overall structure. Thus is used in the aviation and marine fields.
     For the power generation field, it is used because of the fact that it doesn’t need any cooling water. Its sheer simplicity together with the needs for a quick setup and quick start also adds up as the reasons for being used in this field.
In the oil and gas industries, it is used because of the cheaper supply of fuel and low installation costs.
 The following are the limitations of the Gas Turbines:
  1. .    It’s not self-starting.
  2. .       Low efficiencies at part loads.
  3. .       Non-reversibility.
  4. .       High rotor speeds.
  5. .       Overall efficiency is low.
Classifications of Gas Turbines:
The Gas Turbines are mainly classified into the following types:
        1.   Constant pressure combustion Gas Turbines :
             a.   Open Cycle constant pressure gas turbine.
             b.   Closed Cycle constant pressure gas turbine.
        2.       Constant Volume combustion Gas Turbines.


Earlier much heed was paid to the open cycle plants due to the availability of cheap oils and natural gas. But, now as the prices of the oil hike up, there’s a need for the closed cycle plant once again.
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