COGENERATION AND RESIDUAL HEAT RECOVERY (PART B)

Which of the following statements is not correct

• A topping cycle plant generates electricity or mechanical power first

• A bottoming cycle plant generates heat first

• Both a and b

• A bottoming cycle plant generates electricity or mechanical power first

What is a typical efficiency of a cogeneration system?

• 58%

• 85%

• 68%

• 95%

In a combined cycle power plant consisting of gas turbine and waste heat boiler, the exhaust gas temperature is ____.

• around 150 °C

• around 500 °C

• around 300 °C

• around 400 °C

Which of the following depends on physical properties of fluids as well as geometry of the heat exchanger?

• Fouling coefficient

• Overall heat transfer coefficient

• LMTD (Log Mean Temperature Difference)

• Effectiveness

A waste heat recovery system (Shell and Tube heat exchanger) receives hot fluid at 200°C and leaves at 70°C, cold medium enters at 30°C and leaves at 90°C, the type of flow involved in this is

• cross-flow

• co- current flow

• counter-current flow

• none of the above

Radiation recuperators are used when the furnace flue gas temperature is more than

• 200ºC

• 400ºC

• 500ºC

• 800ºC

The major limitation of metallic recuperator is -------

• limitation of handling COx, NOx etc.

• limitation of reduced life for handling temperature more than 1000°C

• manufacturing difficulty of the required design

• none of the above

Combined cycle is a combination of

• conventional boiler first followed by cogeneration system

• Rankine cycle first followed by a Brayton cycle

• Brayton cycle first followed by a standard Rankine cycle

• extraction in the first portion and then a condensing cycle

The efficiency of a stand-alone gas turbine without any heat recovery system will be in the range of

• 10 –15 %

• 15 –20 %

• 20 – 25 %

• 35 – 40 %

Ceramic recuperators can withstand gas side temperature up to

• 400°C

• 1300°C

• 1000°C

• 1700°C