01․ Operating cost of thermal power station is
In case of diesel power plant, the fuel cost and the lubrication cost is higher than that of thermal power plant.
02․ The overall efficiency of a steam power plant equal to
Overall efficiency of steam power plant defined as the ratio of heat equivalent of electrical output to the heat of combustion. It is determined by product the thermal efficiency and electrical efficiency. Thermal efficiency is equal to product of turbine and boiler efficiency. Electrical efficiency is equal to generator efficiency.
03․ In Rankine cycle, the work output from a turbine is given by
In Rankine cycle, turbine would generate no entropy but maximize the network output.
04․ Rankine cycle efficiency of a steam power plant is of
In thermal power plant, the efficiency of Rankine cycle is in the range of 30 to 45 %. The efficiency of the Rankine cycle is limited by the high heat of vaporization of working steam.
05․ Binary vapor cycle are used for
The binary vapor cycle is the combination of two cycle. One operates in the high temperature region, another operates in the low temperature. Thus the plant efficiency improvement in a thermal power plant.
06․ Which of the following contributes to the Rankine cycle efficiency improvement in a thermal power plant
Thermal efficiency of Rankine cycle can be improved by increasing the mean temperature of heat addition, by using of high pressure steam. The mean temperature of heat addition can be increased by using super heat, reheat and regeneration.
07․ The steam power plant efficiency can be improved by
The efficiency of the plant mainly depends upon pressure and temperature of the steam entering the turbine and pressure in the condensor. The thermal efficiency increase with the increase in temperature and pressure of the steam entering the turbine. Thus high temperature and high pressure steam are used in thermal power plant.
08․ Mercury is choice with steam in binary vapor cycle because
Mercury is good working fluid for binary vapor cycle. Its critical temperature is 898° C which is more than metallurgical limit, thus heat can be supplied mercury isothermally at higher temperature. Its critical pressure is only about 18 MPa, thus safer in cycle. Although mercury cannot be used as sole working fluid for entire cycle, since at atmospheric temperature, 32°C, its saturation pressure is too low about 0.07 Pa. Its saturation temperature, 273° C is high as minimum temperature in cycle.
09․ In a thermal power plants, pressure in the working fluid cycle is developed by
In thermal power plant, the pressure in the working fluid cycle is developed by the help to feed water pump.
10․ In a regenerative cycle, feed water is heated by
In a regenerative cycle, feed water is heated by drained steam from turbine. The heating of feed water improves the overall efficiency of the plant.