Chemical Process Industries
Chemical Engineering Department
1
謝志誠
Introduction
Introduction
謝志誠
Summary of the Course
Provide introduction of definition and working principles of equipment for unit operations
coupled with flowsheeting of process design such as PFD and P&ID. Illustration of the chemical
process of various industries such as in refinery, petrochemicals, sulfuric acid, chlor-alkali industry, cement, glass, fertilizer, dairy, sugar, water, soap, etc, with particular emphasis on sultanate
applications.
Dr Salam Al-Dawery 3
謝志誠
Objective of the Course
– Identify the relationship between industrial chemistry and chemical engineering.
– Explain the basic operation of the chemical industry.
– Define a process flow diagram (PFD) and a process and instrumentation diagram (P&ID).
– Create a PFD from a written description of a process.
– Evaluate feeds and products from written descriptions of chemical processes.
– Conduct actual survey of the process operation by visiting the plants.
– Practice research a topic independently or as a team
member, prepare a written and report, and make an oral presentation
Dr Salam Al-Dawery 4
Chapter One
Definition of Chemical Definition of Chemical Engineering
Engineering & Unit Operations
What is Chemical Engineering
• Definition found in a standard dictionary:
“A branch of engineering which involves the design and operation of large scale chemical plants, petrochemical, refineries, and the like.”
• Another definition :
“Concerned with processes that cause substances to
undergo required changes in their chemical or physical composition, structure, energy content or physical
state.”
Chemical Engineer Tasks
• Chemical Engineers convert scientific discoveries into marketable products.
• They are involved in many aspects of chemical production, research, and design, as well as in the construction and
operation of industrial plants.
• They design equipment for safe storage and transportation of chemical solids, liquids, and gases,
• Design control systems for chemical plants based upon data from lab experiments and pilot plant operations.
• Chemical Engineers also perform tests and take
measurements in order to determine the most efficient production methods
General Steps of Chemical Process
SEPARATION PROCESS REACTION PROCESS SEPARATION PROCESS
RAW MATERIALS
INTERMEDIATE PRODUCT
INTERMEDIATE PRODUCT
FINAL PRODUCT
Chemical Process Design
• There is no standard steps
• There is no single correct solution
• There is always a need to find a better
solution from several alternatives
Given Information for a Process Design
• Products needed and production rate
• Purity of the desired product
• Raw material to be used
• Utility available
• The process route
• Expected market
• Site selection
Results of Process Design Project
• Process flowsheet description
• Mass and energy balances results
• Equipment sizing and specification
• Economic feasibility analysis
• Environmental requirements
• The final report
Plant Operation
• In the design of an industrial plant, the methods which will be used for plant operation and control help to determine many of the design variables. For example, the extent of instrumentation can be a factor in choosing the type of process and setting the labor requirements.
• It should be remembered that maintenance work will be necessary to keep the installed equipment and facilities in good operating condition.
Lets look at the overall process flow of a
modern oil refinery:
The overall process is broken down into individual subsets:
Physical Chemical
Thermal Catalytic
Distillation
Solvent extraction Propane deasphalting Solvent dewaxing Blending
Visbreaking Delayed coking Flexicoking
Hydrotreating
Catalytic reforming Catalytic cracking Hydrocracking Catalytic dewaxing Alkylation
With Their Own Flow Arrangement:
Distillation
Fluid Catalytic Cracking
We notice…..
• The number of individual processes is large, each one can be broken down into a series of steps that appear in process after process
• The individual “steps” have common techniques and are based upon the same scientific principles
Fluid Dynamics Heat Transfer Evaporation Humidification Gas absorption
Solvent Extraction Adsorption
Distillation Drying
Mixing
Classification Fluidization Filtration Screening
Crystallization Centrifugation
Materials handling
Fluid Dynamics
A study of the behaviour of fluids
In Chemical processes fluid streams flow from one process to another through pipes and ducts.
Process fluids are moved by pumps and compressors
Fluid flowrates must be monitored by meters and are controlled by valves.
Heat Transfer:
Process fluids may need to be heated up to a certain temperature
Heat from a process
stream may be recovered
This can be done by
contacting two streams in a heat exchanger.
evaporators.mpg
Evaporation:
• A special case of heat transfer, where a phase change takes place.
• Concentrate a solution consisting of a volatile solute and a nonvolatile solvent
• The volatile solute evaporates leaving a more concentrated solution.
Humidification:
Transfer of material between a pure liquid phase and a fixed gas phase that is nearly insoluble in the liquid
Example: Water vapor is added to a air, and thus, cooling tower is used to decrease water temperature
Gas Absorption
• Also known as stripping process
• It is mass transfer operation
• A soluble vapor is absorbed from its mixture with an inert gas by means of a liquid in which the solute gas is more soluble.
• Example: the removal of CO2 and H2S from natural gas or syngas by absorption into amines or alkaline salts
