Answered: Salt can be made from seawater by solar…

Introduction to Chemical Engineering Thermodynamics

8th Edition

ISBN:9781259696527

Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Chapter1: Introduction

Section: Chapter Questions

Problem 1.1P

See similar textbooks

Related questions

Concept explainers

Question

Salt can be made from seawater by solar evaporation. In the first stage of the process, all of the CaCO3 and CaSO4 are precipitated and then the solution is sent to a crystallization pond. In the crystallization pond, water is evaporated and crystalline NaCl is recovered. The pond outlets are a stream containing 91% of the inlet NaCl (pure NaCl crystals) and a stream of mother liquor (the remaining solution), which has an sg of 1.26.

The total salt content of the inlet sea water is 3.7 wt% with an sg of 1.03. The composition of the inlet sea water on a dry basis is 78 wt% NaCl, 11 wt% MgCl2, 4.5 wt% MgSO4, 3.5 wt% CaSO4, 2.5 wt% K2SO4, 0.3 wt% CaCO3 and 0.2 wt% MgBr2. Assume that the losses of NaCl, MgSO4, MgCl2, MgBr2, and K2SO4 are negligible. a) Calculate the water (ton/hr) evaporated for an inlet sea water flowrate of 1 ton/hr. b) Calculate the concentration (wt% total salt) of the mother liquor.

Expert Solution

Step 1

According to the question, the process can be shown by the following flow sheet

if we see both stages as a single unit

Let A,B,C,D be the mass flow rate of (CaCO₃+CaSO₄), NaCl, Water and mother liquor respectively

Step 2

As shown in the Diagram, outle pure NaCl crystals contain 91% of the inlet NaCl

$\begin{array}{rcl} NaCl in crystals, B & = & 0.91 \times 1 \times \frac{3.7}{100} \times \frac{78}{100} \\ = & 0.0263 ton \end{array}$

${CaCO}_{3} + C a S O_{4} in precipitate, A = 1× \frac{3.7}{100} × \frac{(0.3 + 3.5)}{100} =1× \frac{3.7}{100} × \frac{3.8}{100} = 0.0014 ton$

$water in sea water, C=1-3.7 = 0.963 ton$

water in inlet sea water = water evaporated

thus water evaporated = 0.963 ton

Step 3

By total material balance,

$1 = A + B + C + D$

$\begin{array}{rcl} D & = & 1 - (A + B + C) \\ = & 1 - (0.0014 + 0.0263 + 0.963) \\ = & 0.0093 ton \end{array}$

$weight of mother liquor = 0.0093 ton$ $\begin{array}{rcl} N a C l in the mother liquor & = & 9 % of the inltet NaCl \\ = & 1 \times \frac{3.7}{100} \times \frac{9}{100} \\ = & 0.0033 ton \end{array}$

Trending now

This is a popular solution!

Step by step

Solved in 5 steps with 2 images

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemical-engineering and related others by exploring similar questions and additional content below.

Similar questions