Post on 01-Sep-2014
description
WET COOLING TOWER
UNIT OPERATION 3
PREPARED BY: CANOY, CLAIRE E.YR & SEC. : 2B2-CHEMICAL ENGINEERING TECHNOLOGY
WET COOLING TOWER
● Wet cooling towers are heat removal devices used to transfer waste heat from industrial and other processes to the atmosphere.
●They are used primarily to provide circulating cooling water in large industrial facilities.
OPERATION
The warm water returns to the top
of the cooling tower and trickles
downward over the fill material
inside the tower.
As it trickles down, it contacts the fan-induced upward flow of
ambient air.
OPERATION
That contact causes a portion of the water (E)
to evaporate into water vapor that exits the tower as part of the
water saturated air.
OPERATION
A small amount of the water also exits with the air
as entrained droplets of liquid water called drift
losses (D).
OPERATION
The heat required to evaporate the water is derived from the water
itself, which cools the water back to the original basin
water temperature and the water is
then ready to recirculate.
OPERATION
The evaporated water leaves its dissolved salts behind in the
bulk of the water which has not
been evaporated, thus raising the salt
concentration in the circulating cooling water.
OPERATION
To prevent the salt concentration of the
circulating water from becoming too high, a portion of
the water, referred to as blowdown(B, is
drawn off for disposal.
OPERATION
Fresh water make-up (M) is supplied to the tower basin to
compensate for the loss of evaporated
water, the drift loss water and the blowdown
water.
OPERATION
ACTUAL AIR-TO-WATER FLOW ARRANGEMENTS
AIR-TO-WATER FLOW ARRANGEMENTS
APPLICATION
● A cooling tower serves to dissipate the heat into the atmosphere where wind and air diffusion spreads the heat over a much larger area than warm water can distribute heat in a body of water.
● Industrial cooling towers is to reject the heat absorbed in the circulating cooling water systems used in industrial facilities such as petroleum refineries, natural gas treating plants, petrochemical and other chemical plants, and electric power plants (both thermal and nuclear).
APPLICATION