Question: A chemical inhibitor must be added to the water in a boiler to avoid corrosion and scale. The inhibitor concentration must be maintained between 3 and 30 ppm. The boiler system always contains 100,000 kg of water and the blowdown (purge) rate is 15,000 kg/hr. The makeup water contains no inhibitor. An initial 2.8 kg of inhibitor is added to the water and thereafter 2.1 kg is added periodically. What is the maximum time interval until the first edition of the inhibitor? -Free Course Hero Question Answer.

Question Description: A chemical inhibitor must be added to the water in a boiler to avoid corrosion and scale. The inhibitor concentration must be maintained between 3 and 30 ppm. The boiler system always contains 100,000 kg of water and the blowdown (purge) rate is 15,000 kg/hr. The makeup water contains no inhibitor. An initial 2.8 kg of inhibitor is added to the water and thereafter 2.1 kg is added periodically. What is the maximum time interval until the first edition of the inhibitor?

Overall material balance dM
=ṁ 1−ṁ2
dt Component material balanced
ω A M ) =ω1A ṁ1−ω2A ṁ2
(
dt
Can be transformed: d ( ω A M ) =( ω 1A ṁ1−ω 2A ṁ2) dt
Integration from 0 to t will give: dM =(ṁ1−ṁ2 )dt
t M =∫ (ṁ 1−ṁ2) dt
0 M =( ṁ1−ṁ2)×t
t ω A M =∫ ( ω 1A ṁ1−ω2A ṁ 2) dt