Chemical Engineering Cheat Sheet

The core ideas of Chemical Engineering distilled into a single, scannable reference — perfect for review or quick lookup.

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Quick Reference

Mass and Energy Balances

The foundational accounting tools of chemical engineering that apply conservation laws to track every kilogram of material and every joule of energy entering, leaving, and accumulating within a process system.

Thermodynamics

The study of energy transformations and equilibrium states that governs feasibility, efficiency, and equilibrium composition of chemical processes. Chemical engineers use it to predict phase behavior, reaction spontaneity, and maximum work extraction.

Transport Phenomena

The unified study of momentum transfer (fluid flow), heat transfer, and mass transfer. These three phenomena are governed by analogous mathematical equations and determine the rates at which processes occur.

Chemical Reaction Engineering

The sub-discipline focused on the design and operation of chemical reactors. It combines reaction kinetics (how fast reactions occur) with transport and mixing phenomena to predict reactor performance and select optimal reactor types.

Unit Operations

The fundamental physical and chemical steps that make up any chemical process, such as distillation, absorption, extraction, filtration, drying, crystallization, and evaporation. Each unit operation can be analyzed and designed using consistent engineering principles.

Process Design and Simulation

The systematic methodology for developing a chemical process from concept to detailed engineering drawings, including process flow diagrams (PFDs), piping and instrumentation diagrams (P&IDs), and equipment sizing, often aided by software simulators like Aspen Plus or HYSYS.

Process Control

The engineering practice of maintaining process variables (temperature, pressure, flow rate, composition) at desired setpoints using feedback and feedforward control systems, ensuring product quality, safety, and efficiency.

Separation Processes

The techniques used to divide mixtures into their components, which typically account for 40-70% of both capital and operating costs in a chemical plant. Key methods include distillation, membrane separation, adsorption, and chromatography.

Process Safety and Risk Management

The discipline focused on preventing catastrophic incidents in chemical facilities through hazard identification (HAZOP), risk assessment, inherently safer design, layers of protection analysis (LOPA), and safety instrumented systems.

Catalysis

The acceleration of chemical reactions by substances (catalysts) that are not consumed in the process. Catalysts are critical to the chemical industry, enabling reactions to occur at lower temperatures and pressures with higher selectivity.

Key Terms at a Glance

Absorption:A mass transfer operation where a gas-phase component is dissolved into a liquid solvent.

Activation Energy:The minimum energy required for reactant molecules to undergo a chemical reaction.

Adiabatic:A process or system with no heat transfer to or from the surroundings.

Batch Reactor:A reactor where all reactants are charged at the start, the reaction proceeds, and products are removed at the end with no flow during the reaction.

Bernoulli's Equation:An equation relating pressure, velocity, and elevation for steady, incompressible, frictionless fluid flow.

Catalyst:A substance that increases the rate of a chemical reaction by lowering activation energy without being consumed.

Chemical Kinetics:The study of reaction rates and the factors (temperature, concentration, catalysts) that influence how fast reactions occur.

CSTR:Continuously Stirred Tank Reactor; an ideal reactor model assuming perfect mixing throughout the vessel.

Distillation:A separation process that exploits differences in component volatilities (boiling points) to separate liquid mixtures.

Endothermic:A reaction or process that absorbs heat from its surroundings, resulting in a positive enthalpy change.

Enthalpy:A thermodynamic property representing the total heat content of a system at constant pressure ($H = U + PV$).

Entropy:A thermodynamic measure of disorder or randomness in a system; the Second Law states it always increases in an isolated system.

Exothermic:A reaction or process that releases heat to its surroundings, resulting in a negative enthalpy change.

Fick's Law:A law stating that the rate of diffusion is proportional to the concentration gradient.

Fluidized Bed:A bed of solid particles suspended by an upward flow of fluid, providing excellent mixing and heat transfer.

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