Chemical Engineering

Chemical engineering scales molecular-level chemistry to industrial processes — refining, petrochemicals, pharmaceuticals, food, polymers, semiconductors, and clean energy.

Overview

The discipline rests on three legs: transport phenomena (momentum, heat, mass), thermodynamics & kinetics (equilibrium and reaction rates), and unit operations & process design. PFDs and P&IDs are the working drawings of the field.

Unit Operations

• Separations — distillation, absorption, extraction, membrane, crystallization.
• Heat transfer — shell-and-tube and plate exchangers, fired heaters, reboilers.
• Fluid flow — pumps, compressors, control valves, piping.
• Reaction — CSTR, PFR, batch, packed-bed, fluidized-bed.
• Solids handling — drying, milling, conveying, filtration.

Mass & Energy Balances

Steady-state inputs equal outputs plus accumulation. Always define the system boundary first, then write a balance on each component and on total enthalpy. McCabe–Thiele, Ponchon–Savarit, and shortcut Fenske–Underwood–Gilliland methods are still the fastest way to size a distillation column before rigorous simulation.

Reactor Design

• Batch: dC_A/dt = −r_A
• CSTR: V = F_A0·X / (−r_A)
• PFR: V = F_A0 · ∫₀ˣ dX / (−r_A)
• Arrhenius: k = A·exp(−E_a/RT)

Process Safety

Loss of containment is the dominant hazard. Standard tools: HAZOP, LOPA, what-if/checklist, FMEA. SIL ratings (per IEC 61511) quantify the risk reduction of safety instrumented functions. OSHA 29 CFR 1910.119 (PSM) governs facilities handling highly hazardous chemicals.

Tools & Standards

• Simulation: Aspen Plus, Aspen HYSYS, ChemCAD, PRO/II, gPROMS.
• Heat exchangers: HTRI, Aspen EDR.
• Process safety: PHAST, DNV Safeti.
• Standards: ASME B31.3 (process piping), API 520/521 (relief), API 650 (tanks), ISA-5.1 (P&ID symbols).