# 100 KLD Multiple Effect Evaporator (MEE), VOC Stripper & Vacuum ZLD Sizer

In active pharmaceutical ingredient (API) manufacturing and specialty chemical synthesis plants, Zero Liquid Discharge (ZLD) thermal trains handle complex wastewater streams containing volatile organic solvents and high total dissolved solids (TDS).

This technical documentation outlines the mass-energy balance, pre-stripper surface condenser rating, MEE vacuum pump sizing, and Technoforce hybrid 40% TDS outlet topology.

# 1. Conservative Design Basis (20 Hours/Day)

Designing ZLD plants for 20 operating hours per day reserves 4 hours daily for mandatory CIP acid/alkali washing and descaling:

\text{Hourly Feed Rate } F = \frac{100,000 \text{ kg/day}}{20 \text{ h/day}} = \mathbf{5,000 \text{ kg/h}} \quad (5.00 \text{ m}^3/\text{h})

# Feed Composition (5,000 kg/h Basis)

Volatile Organic Solvents (VOCs): $10.0\% \text{ w/w}$ ( $500 \text{ kg/h}$ )
Inorganic TDS ( $x_F$ ): $5.0\% \text{ w/w}$ ( $250 \text{ kg/h}$ )
Water ( $\text{H}_2\text{O}$ ): $85.0\% \text{ w/w}$ ( $4,250 \text{ kg/h}$ )

# 2. Upstream VOC Stripper Column & Overhead Surface Condenser

# Stripper Operating Parameters

Column Type: Packed column with Sulzer Mellapak 250Y structured packing.
Live Stripping Steam: $625 \text{ kg/h}$ ( $1.5 \text{ bar(g)}$ ).
Overhead Vapor: $500 \text{ kg/h}$ VOCs $+ 150 \text{ kg/h}$ water vapor $= 650 \text{ kg/h}$ at $82^\circ\text{C}$ .
Residual VOC in Bottoms: $< 100 \text{ ppm}$ (sent cleanly as MEE feed).

# Stripper Surface Condenser Sizing ( $A_{cond,strip}$ )

Q_{strip} = \frac{650 \text{ kg/h} \times 900 \text{ kJ/kg}}{3,600} = \mathbf{162.5 \text{ kW}}

A_{cond,strip} = \frac{162.5 \text{ kW}}{0.85 \cdot 24.5^\circ\text{C}} = \mathbf{7.6 \text{ m}^2} \quad (\text{SS316L Tubes})

# 3. MEE 40% TDS Outlet Brine Slurry Mass Balance

\text{MEE Feed Rate } F_{MEE} = 4,500 \text{ kg/h} \quad (5.56\% \text{ TDS})

\text{Effect 3 Brine Slurry Outlet } C_{40\%} = \frac{250 \text{ kg/h}}{0.40} = \mathbf{625 \text{ kg/h}} \quad (40.0\% \text{ w/w TDS})

\text{Water Evaporation in 3-Effect MEE } V_{total} = 4,500 - 625 = \mathbf{3,875 \text{ kg/h}} \quad (91.18\% \text{ Recovery})

\text{ATFD Evaporation Duty } V_{ATFD} = 625 - 250 = \mathbf{375 \text{ kg/h}} \quad (\text{Dry Salt Output } = 250 \text{ kg/h})

# 4. MEE Vacuum System & Main Surface Condenser Rating

# Liquid Ring Vacuum Pump (LRVP)

Vacuum Operating Pressure: $-0.88 \text{ bar(g)}$ ( $0.12 \text{ bar(a)}$ absolute / $90 \text{ mmHg}$ ).
Motor Size: $15.0 \text{ kW}$ 2-Stage LRVP Package with Air Ejector Booster.

# Main MEE Surface Condenser Area ( $A_{cond,MEE}$ )

Q_{cond,MEE} = \frac{1,350 \text{ kg/h} \times 2,362 \text{ kJ/kg}}{3,600} = \mathbf{885.8 \text{ kW}}

A_{cond,MEE} = \frac{885.8 \text{ kW}}{0.95 \cdot 14.5^\circ\text{C}} = \mathbf{64.3 \text{ m}^2} \quad (\text{SS316L Tubes})