Related Questions

For raschig rings, the sphericity is
A 0.5
B 1
C $$\sqrt 3 $$
Lessing ring is formed by the addition of a partition across the centre of a raschig ring, which results in an area increase of about __________ percent.
A 5
B 20
C 35
D 55
Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity?
A Sphere
B Cube
C Cylinder (L/D = 1)
D Raschig rings
Raschig ring made of procelain cannot be used for treating concentrated
A Hydrochloric acid
B Nitric acid
C Alkalis
D Sulphuric acid
Maximum size of the raschig rings used in a packed tower is about __________ of the coloumn diameter.
A $${\frac{1}{{10}}^{{\text{th}}}}$$
B $${\frac{1}{{20}}^{{\text{th}}}}$$
C $${\frac{1}{{30}}^{{\text{th}}}}$$
D $${\frac{1}{{50}}^{{\text{th}}}}$$
Diameter of raschig rings used in packed tower in industry is normally around __________ inches.
A 2
B 8
C 12
D 18
M.I. of a thin ring (external diameter D, internal diameter d) about an axis perpendicular to the plane of the ring, is
A $$\frac{\pi }{{64}}\left( {{{\text{D}}^4} + {{\text{d}}^4}} \right)$$
B $$\frac{\pi }{{32}}\left( {{{\text{D}}^4} - {{\text{d}}^4}} \right)$$
C $$\frac{\pi }{{32}}\left( {{{\text{D}}^4} + {{\text{d}}^4}} \right)$$
D $$\frac{\pi }{{32}}\left( {{{\text{D}}^4} \times {{\text{d}}^4}} \right)$$
Use of raschig rings in place of crushed stones as packing in packed beds (other things being same)
A Increases pressure drop, increases surface area
B Increases pressure drop, decreases surface area
C Decreases pressure drop, increases surface area
D Decreases pressure drop, decreases surface area
Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is
A 0.5
B 1
C $$\sqrt 2 $$
D $$\sqrt 3 $$
Reciprocal of sphericity is termed as the
A Specific surface ratio
B Shape factor
C Sauter diameter
D Surface area per unit mass

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