In
the chemical pulping process, cooking liquor (spent liquor) that is
separated from the washed stock goes through an evaporation process
to form black liquor. The black liquor becomes fuel for the recover
boiler. The resulting furnace smelt is dissolved to form green liquor.
After a clarification process (removal of insoluble material,) the green
liquor is fed into a lime slaker where it mixes and reacts with lime.
White liquor is produced, which in turn is used in the pulp cooking
process. The reaction in the slaker takes place at temperatures around
185- 195°F. Overheating of green liquor does not improve causticizing
reaction efficiency and presents the risk of boil over.
The Solution:
The Pick
Direct Steam Injection Constant Flow Heater Model 6X75-3
was selected for added capacity. The Pick Hater can automatically adapt
to changes of incoming liquor temperature. The heater was provided in
316L grade stainless steel to better handle caustic green liquor. The
mill DCS controlled the discharge temperature of the heater.
Features and Benefits:
• Smooth, Quiet
Performance
• Precise Temperature Control