1051. The following are the forces acting on a particle that settles in a fluid:
A. Gravitational and buoyant forces
B. Centrifugal and drag force
C. Gravitational or centrifugal buoyant and drag forces *
D. External , drag and viscous forces
1052. Terminal velocity is :
A. A steady speed with no speed increase *
B. A fluctuating velocity
C. Reached after covering half of the total distance
D. None of these
1053. In hindered settling , particles are :
A. Placed further from the wall
B. Unaffected by the wall and other particles
C. Near each other *
D. None of these
1054. Drag co-efficient in hindered settling is ________ that in free settling:
A. Leaser than
B. Equal to
C. Not necessarily greater than
D. Always greater than *
1055. The slope of the CD-log NRe plot is as follows for the free settling of a spherical particle through a fluid:
A. 1
B. -1 *
C. 0.5
D. -0.5
1056. In continuous fluidisation:
A. Solids are completely entrained *
B. The strain drop is not exactly that for clump fluidisation
C. There is no entertainment of solids
D. Speed of the liquid is tiny
1057. The pressure drop in a fluidized bed reactor is ______ times that of a packed bed reactor of the same type:
A. Less than
B. More than *
C. Same as
D. None of these
1058. Slugging in a fluidised bed can be tried not to by utilize :
A. Tall narrow vessel
B. Deep bed of solids
C. Shallow beds of solids and proper choice of particles size *
D. Very large particles
1059. Minimum porosity for fluidisation is :
A. That corresponding to static bed
B. That corresponding to completely fluidised bed
C. The bed’s porosity at the beginning of true fluidization *
D. Much less than the static bed’s
1060. In a fluidised bed reactor :
A. Temperature gradients are very high
B. The temperature is roughly constant *
C. Hot spots are formed
D. Segregation of the solids occurs