SODA RECOVERY

359

all the sodium carbonate, and this is drained to a pump through perforated
tiles in the bottom of the soaking tank. This liquor is then pumped to a
causticising pan (Fig. 156) with a half-round bottom and a mechanical

FLOW

DIAGRAM

BLACK LIQUOR INLET

FLUE GAS To CHIMNEY

ROTARY__FURNACE

" ECONOMISER

DELIVERY END

FIRST EFFECT I*"\/AC.

FEED LIQUOR

EXTRA
STEAM

SECOND EFFECT 28"VAe.

CONDENSER

INJECTED WATER

AIR PUMP

HALF STRONG LIOUOR-

STEAM
CONCENTRATOR

STEAM TRAP

CoNDENSATE FuMP

THIRD EFFECT
— CONCENTRATOR

CONCENTRATOR
FEED F\JMP

THICK LIQUOR To ROASTER

\

FIG. 157.—FLOW DIAGRAM OF CAUSTIC SODA RECOVERY PROCESS