A. An increase in liquid viscosity
B. An increase in relative volatility for rectification columns
C. Decrease in gas solubility for absorbers
D. All A., B. and C.
Related Mcqs:
- Height equivalent to a theoretical plate (HETP) is the height of packing that will give the same separation as one theoretical plate in gas-liquid mass transfer operations like distillation, absorption/stripping and humidification/dehumidification. HETP which is experimentally determined, depends upon the_______________?
A. Flow rates of each fluid
B. Type and size of packing
C. Concentration of each fluid
D. All A, B. & C. - A high vapour velocity is required for high plate efficiency in a sieve plate column. The satisfactory value of operating vapor velocity for design purpose in sieve plate column is about _______________ percent of the flooding velocity?
A. 45
B. 60
C. 80
D. 95 - Overall mass transfer co-efficient in case of absorption of __________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling ?
A. CO2
B. SO2
C. NH3
D. None of these - In a shell and tube heat exchanger, the overall heat transfer co-efficient is proportional to the tube side (volumetric flow rate)0.8. This is valid, only when the ratio of the tube side film resistance to the total resistance is almost equal to____________________?
A. ∞
B. 1
C. 20.8
D. 2 - To avoid the tearing off the plate of an edge, the margin (i.e., the minimum distance from the centre of the rivet hole to the nearest edge of the plate) should be equal to ____________________?
A. 0.5 d
B. d
C. 1.5 d
D. 2.5 d - A perforated plate has holes of diameter dn arranged in a pitch ph. Each hole has a tube of I.D. dt passing through it. The ligament efficiency is given by_______________?
A. (ph – dh)/ph
B. (ph – dh . dt/2)/ph
C. (ph – dt)/ph
D. (ph – dh)/dh - Maximum plate efficiency is achieved in case of ______________ flow?
A. Split
B. Cross
C. Cascade
D. Reverse - The thickness of heat transfer plates used in the plate type heat exchanger ranges from _____________ mm, pressed in a single piece provided with grooves & corrugations?
A. 0.3 to 0.8
B. 1.25 to 3.125
C. 3.5 to 7.0
D. 8 to12 - For a cylindrical vessel of moderate height, the weld joint efficiency for joints parallel to the cylindrical axis is given as 1.0; while for joints along the girth (circumference) it is given as 0.8. In calculating the shell wall thickness using code formula for an internally pressurised cylindrical vessel, what value of weld joint efficiency should be used ?
A. 0.8
B. 0.9
C. 1.0
D. (0.8)0.5 - Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07 – 1.4 cp and relative volatility < 4) (where ε = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi) ?
A. η = 17 – 61.1 log μ
B. η = 24.6 (Δp/μ)
C. η = 1.66 – 0.25 log μ
D. η = 0.25 log μ – 1.67
