Question

(1). (5%) If one wants to increase the height-to-diameter ratio of a tray tower for a given actual number of trays, one should consider to change__________________.

(2). (5%) For a packed tower, the height-to-diameter ratio is determined by ____________ and ____________.

(3). (5%) For efficient stripping of ammonia from a wastewater stream, the best type of mass transfer equipment should be a _______________.

(4). (5%). For a batch distillation tray tower, one can maintain a constant distillate product concentration via changing _______________.

(5). (5%) For a given liquid flow rate in a tray tower, the upper gas flow limit is defined by _______________, and the lower limit of the gas flow rate is set by ______________.

(6). (5%) For a distillation column with infinite number of trays, the energy input from the reboiler, Q_w, is ______ for batch distillation than continuous distillation to achieve the same separation at the same process capacity.

(a) higher; (b) lower; (c) the same as (d) not certain.

(7). (10%) For a given binary distillation tower with a vapour feed at dew point, during the steady state operation, the feed changes to a mixture of 50 mol% vapour and 50 mol% liquid for some reason, while the feed rate F remains unchanged. If the reflux ratio R remains the same, the composition x_D will ________, and x_W will _______.

(a) increase; (b) decrease; (c) remain constant; (d) not certain.

(8). (10%) For a packed tower striper of dilute system, if the inlet liquid phase concentration decreases while the other operating parameters remain the same then: N_tOL will ______, H_tOL will _______; the outlet liquid concentration will _______; the exiting gas concentration will ________.

(a) increase; (b) decrease; (c) remain the same; (d) not certain

Answer 1