Abstract:
Boilers are operated at 6-10% blowdown to ensure the safe operation. However,
a significant amount of energy associated with the high temperature boiler
blowdown is wasted when it is not treated within the plant. This project focuses
on reducing the energy loss by reusing blowdown water after processing and
reusing its TDS to useable limits. Up-to 95%-98% of the blowdown can be
recovered and reused as boiling feed water (BFW). The water required will
require less chemical dosing and energy to form steam. If this water is reused, the
make-up requirement will also decline. Falling film evaporator is required along
with preheater which follows vapor compression cycle. Compressed vapor
(Evaporated water) are source of heat in evaporator that condenses to form
distillate. Steam will be needed for start-up but continuous operation can be
maintained by compressed vapor after startup. Crystallizer will be used for
removing of high concentrated sludge and recover condensate water to improve
the treatment up to 98%. The higher is the blowdown temperature , easier will be
the evaporation and lesser would be the operating cost. In case of Attock Refinery
Limited, up to 95%-98% of blowdown water can be saved at the expense of 145
KW compressor
