An integrated pulp and paper mill produces two paper grades (SC paper, LWC paper) and pulp at the mill site. Chemical pulp is made of pine chips and TMP-mill uses spruce chips as raw material. Round wood (pine) is transported to the mill to produce pine chips. Spruce chips are obtained from a sawmill near to the pulp and paper mill. Table 1 shows daily demands of chemical and mechanical pulp.

Table 1. Daily demands of pine and spruce chips

Pulp Daily demand	tds/d
Pine chips	2214
Spruce chips	939

SC Super Calendered

LWC Light Weight Coated

A) Evaporator

Initial data

Mass flow rate of black liquor, in 1742 tds/d

Dry solids content of weak black liquor 18 %

Dry solids content of strong black liquor 80 %

Production of tall oil 14 kg/tds (pine chips)

Calculate how much water is evaporated in the black liquor evaporator (t/d).

Calculate also the mass flow rate of strong black liquor (tds/d).

B) Recausticizing

Initial data:

White liquor demand 2928 m3/d

Demand of CaO 81 kg/m3 white liquor

Production of CaCO3 130 kg/ m3 white liquor

Conversion factor from CaCO3 to CaO 0.58 t/t lime mud

Calculate how much make-up lime is needed (tds/d).