Q4 Find the surface area required in a counter flow steam superheater in which the steam enters at 180 0C in a dry saturated state and leave at 250 0C with an increase of enthalpy of 159 kj/kg. the combustion gases (Cp = 1.5kj/kgk) enter the superheater at 510 0C. the steam flow rate is 1000 kh/h,the hot gas flow rate is 2000 kg.h, and the overall heat transfer coefficient is 26 W/m2K. 5 3 1,3,12 ?
Answers
Answer:
1 mole of H
2
SO
4
⋅5H
2
O will be formed.
Heat absorbed =Ne⋅ΔH for 1 mole=580.32 kJ
1 mole=188 g of H
2
SO
4
⋅5H
2
O
∴580.32×10
3
=188×4.184×ΔT
∴ΔT=737 K
Answer:
SUPERHEATED STEAM
An explanation of the properties and uses of superheated steam (such as for electricity generation). Including explanations of the Rankine and Carnot thermodynamic cycles, superheated steam tables and the Mollier (H-S) chart.
If the saturated steam produced in a boiler is exposed to a surface with a higher temperature, its temperature will increase above the evaporating temperature.
The steam is then described as superheated by the number of temperature degrees through which it has been heated above saturation temperature.
Superheat cannot be imparted to the steam whilst it is still in the presence of water, as any additional heat simply evaporates more water. The saturated steam must be passed through an additional heat exchanger. This may be a second heat exchange stage in the boiler, or a separate superheater unit. The primary heating medium may be either the hot flue gas from the boiler, or may be separately fired.