Evaporator Solute Balance: Concentration Increase Requires a Nonvolatile Inventory

Define the Phase or Process Boundary

NPTEL's evaporator mass balances distinguishes feed, concentrate and vapor. For a steady model with no solute in vapor, solute feed equals solute in concentrate. The total balance then determines vapor removed; the solute-free-vapor assumption must remain explicit.

Review a Hypothetical Comparison

Imagine an assigned feed of 250 kg/h containing 12% solute by mass and a concentrate target of 40%. Solute feed is 30 kg/h. With no other outlets or accumulation, concentrate flow is 30/0.40=75 kg/h and vapor flow is 250−75=175 kg/h. Concentrate contains 45 kg/h solvent, while feed contains 220 kg/h solvent; 220−45 also gives 175 kg/h. The two closures help expose a concentration basis or outlet error.

Keep the Evidence with the Decision

Draw all streams and name what the concentration fraction includes. Record any entrained droplets, volatile solute, sample withdrawal or retained material separately if they cross the boundary. Keep transient inventory change visible when a batch concentration is being compared with a steady-flow calculation.

The assigned target and streams are fictional. This balance does not calculate steam consumption, heating area, product exposure or a feasible evaporation rate.

What feed and product flows close the nonvolatile-solute inventory before water removal is calculated?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• NPTEL's evaporator mass balances
• Reference from hmpharmamachines.com