Steam turbines advantages

Water Consumption and Effluent Characterization. Another advantage of CGCC power generation is derived from lower water requirements. Because more than half of the power generated in a CGCC plant comes from the gas turbine, the water requirement is only 70—80% of that required for a coal-fired power plant, where all of the power is generated from steam turbines. 

The advent of electric motors, steam turbines, and other drivers has relegated the steam engine to a minor position as an industrial driver. It does have the advantages of reliabihty and operating characteristics that are not obtainable with other drivers but so the disadvantage of bulldness and oily exhaust steam. 

It is advantageous to have the expander generate its refrigeration at the lowest possible temperature in the process (see Fig. 29-45), and this frequently encounters the condensation temperature of the pi ocess stream. Steam-turbine pracrice advises against operating on... 

Electric motors may be considered in cases where it is considered advantageous to export surplus steam outside the nitric acid plant. Condensing steam turbines are normally used to bridge the power deficit. Extraction-condensing turbines make it possible to use some of the available steam for heating purposes. 

Natural gas also has an efficiency advantage in electricity generation. The economic and operational superiority of gas-fired combustion turbines and combined-cycle machines (and prospectively, the superiority of gas-powered fuel cells) relative to coal-and nuclear-powered steam turbines made the combination of natural gas and natural gas turbines the supply favorite of most electric utilities in the 1990s. 

Compressors are of two general classes positive-displacement or centrifugal. The positive-displacement compressor simply compresses an initial gas volume to a final smaller volume in a closed containment a centrifugal compressor compresses gas by changing its velocity. Each of the common types of compressors has their advantages and applications. Drivers for compressors may be either electric motors, steam turbines or gas turbines. 

Medium-pressure steam is produced in this process to provide some plant heating/energy requirements. An economic advantage is the income derived from the export of excess steam. The steam specification corresponds to requirements for in-house application at the steam turbine, and also in response to the needs of the adjacent ammonia plant. The final steam specification is a superheated medium-pressure product at 380°C and 4000 kPa. 

The steam turbine provides mechanical energy, which can be transformed into electrical energy by means of a generator. The advantage of this is that it allows for transportation of the electricity at high voltages. 

Rotational speeds vary from approximately 1,800 to 14,000 rpm and can be modulated over a wide range. Such variable speed is an advantage if the turbine is used to drive pumps and compressors or if it is to convert a variable steam flow into electricity, as is the case with thermal solar systems. When provided with the appropriate speed governor, steam turbines can provide excellent speed stability, which is desirable when the turbine serves as the prime mover in electric generators. 

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