Question

The maximum amount of total solids allowed in a boiler is 800 mg/L. The feed water has 10 mg/L solids. If the boiler produces 40,000 kg/hr stream, calculate the amount of water removed per hour  by making a blow down.

Answer 1

Drying is a mass transfer process consisting of the removal of water or another solvent^[1] by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be considered "dried", the final product must be solid, in the form of a continuous sheet (e.g., paper), long pieces (e.g., wood), particles (e.g., cereal grains or corn flakes) or powder (e.g., sand, salt, washing powder, milk powder).

Total Material Balance: Feed= W + 40, 000 -----eq1

Solid Balance: 10F=0 + 800W----eq 2

40,000 kg/hr (cubic meter/ 1000 kg) (1000L/cubic meter) = 40,000 L/hr

solving equation 1 and 2:

F=40, 506.3292 L/hr

W= 506.3291 kg/hr

Therefore the amount of water removed by making a blow down per hour is 506.3291 kg.