1. Chemical Process Industries
Chemical Engineering Department

2. CHPE 306 Chemical Process Industries
Fall
Instructor : Dr. Sri Hari Kumar Annamareddy
Room

3. Chemical Process Industries
ASSESSMENTS
Course Works
Assignments (2) %
Quizzes (2 ) %
Project and /or Site visit
Reports (2) %
Two Mid-term exams (2) %
Final Examination
40%
TEXT BOOK
Austin, G.T., "Shreve's Chemical Process Industries", 5th ed McGraw- Hill: New York, 1984. 3

4. Introduction
Dr Salam Al-Dawery

5. Summary of the Course
Provide introduction and working principles of equipment for unit operations coupled with flow sheeting of process design such as PFD and P&ID.
Illustrates 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
Dr Salam Al-Dawery

6. Objectives of the Course
Explain the basic operation of the chemical industry.
Define the process flow diagram (PFD) and process and instrumentation diagram (P&ID).
Create a PFD from a written description of a process.
Evaluate raw materials and products from written description of chemical processes.
Prepare a report and make an oral presentation.
Dr Salam Al-Dawery
Dr Salam Al-Dawery

7. Definition of Chemical Engineering & Unit Operations
Chapter One
Definition of Chemical Engineering & Unit Operations
Dr Salam Al-Dawery

8. What is Chemical Engineering
Definition found in 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.”
Dr Salam Al-Dawery

9. Chemical Engineer Tasks
Chemical Engineers are responsible for converting 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 equipments 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
Dr Salam Al-Dawery

10. General Steps of Chemical Process
SEPARATION PROCESS
REACTION PROCESS
RAW MATERIALS
INTERMEDIATE PRODUCT
FINAL PRODUCT
Dr Salam Al-Dawery

11. Chemical Process Design
No standard steps for process design
No single correct solution
There is always a need to find a better solution from several alternatives
Dr Salam Al-Dawery

12. Given Information for a Process Design
Products needed and production rate
Purity of the desired product
Raw materials to be used
Utilities available
The process route
Expected market
Site selection
Dr Salam Al-Dawery

13. 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
Dr Salam Al-Dawery

14. 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.
Dr Salam Al-Dawery

15. Lets look at the overall process flow of a modern oil refinery:
Dr Salam Al-Dawery

16. 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
Dr Salam Al-Dawery

17. Distillation
Dr Salam Al-Dawery

18. Fluid Catalytic Cracking
Dr Salam Al-Dawery

19. We notice….. Fluid Dynamics Heat Transfer Evaporation Humidification
The number of individual processes are 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
Dr Salam Al-Dawery

20. 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.
Dr Salam Al-Dawery

21. 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.
Dr Salam Al-Dawery

22. 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.
Dr Salam Al-Dawery

23. 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 air, and thus, cooling tower is used
to decrease water temperature
Dr Salam Al-Dawery

24. 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
Dr Salam Al-Dawery

25. Leaching or Liquid extraction1/3
Leaching is a process in which the solid extraction involves the dissolving of soluble matter from its mixture with an insoluble solid
Liquid extraction is the separation of two miscible liquids by the use of a solvent that preferentially dissolves one of them.
Liquid extraction an alternative to distillation for difficult separations
Example: leaching oil from seeds, and penicillin is separated from fermentation broth by extraction with butyl acetate
Dr Salam Al-Dawery

26. Leaching or Liquid extraction2/3
Dr Salam Al-Dawery

27. Leaching or Liquid extraction3/3
Solvent
Extract
Feed
Raffinate
Dr Salam Al-Dawery

28. Distillation
Flash distillation: production of a vapour by boiling the liquid mixture to be separated and then condensing the vapours without returning any to the still.
Return part of the condensate to the still under conditions where it can be in contact with the vapours on their way to the condenser. (rectification)
Either operation may be done in batch or continuous mode.
Dr Salam Al-Dawery

29. How does distillation work? 1/3
Distillation is defined as:
a process in which a liquid or vapour mixture of two or more substances is separated into its component fractions of desired purity, by the application and removal of heat.
Dr Salam Al-Dawery

30. How does distillation work? 2/3
Distillation is based on the fact that the vapour of a boiling mixture will be richer in the components that have lower boiling points.
Thus, when this vapour is cooled and condensed, the condensate will contain the more volatile components. At the same time, the original mixture will contain more of the less volatile components.
Distillation is the most common separation technique and it consumes enormous amounts of energy, both in terms of cooling and heating requirements.
Distillation can contribute to more than 50% of plant operating costs.
Dr Salam Al-Dawery

31. How does distillation work? 3/3
Distillation columns are classified by the manner in which they are operated:
Batch, in which the feed to the column is introduced batch-wise. That is, the column is charged with a 'batch' and then the distillation process is carried out. When the desired task is achieved, a next batch of feed is introduced.
Continuous columns process a continuous feed stream. No interruptions occur unless there is a problem with the column or surrounding process units. They are capable of handling high throughputs and are the most common of the two types.
Dr Salam Al-Dawery

32. Continuous Distillation Columns
Classified according to:
Nature of the feed that they are processing:
Binary column - feed contains only two components;
Multi-component column - feed contains more than two components.
Number of product streams they have:
Multi-product column - column has more than two product streams.
Where extra feed exits when used to help with the separation:
Extractive distillation - where the extra feed appears in the bottom product stream;
Azeotropic distillation - where the extra feed appears at the top product stream.
Type of column internals:
Tray column - trays of various designs used to hold up the liquid to provide better contact between vapour and liquid;
Packed column - packings are used to enhance vapour-liquid contact.
Dr Salam Al-Dawery

33. Main Components of Distillation Columns
A vertical shell where separation of liquid components is done.
Column internals e.g.trays/plates and/or packings which are used to enhance component separations.
A reboiler to provide the necessary vaporization for the distillation process.
A condenser to cool and condense the vapour leaving the top of the column.
A reflux drum to hold the condensed vapour from the top of the column so that liquid (reflux) can be recycled back to the column.
Dr Salam Al-Dawery

34. Liquid And Vapour Flows in A Tray Column
Dr Salam Al-Dawery

35. Trays and Plates1/2 Bubble cap trays
A riser or chimney is fitted over each hole, and a cap covers the riser. The cap is mounted with a space to allow vapour to rise through the chimney and be directed downward by the cap, finally discharging through slots in the cap, and bubbling through the liquid on the tray.
Dr Salam Al-Dawery

36. Trays and Plates2/2 Valve trays Sieve trays
Perforations are covered by caps lifted by vapour, which creates a flow area and directs the vapour horizontally into the liquid.
Sieve trays
Sieve trays are simply metal plates with holes in them. Vapour passes straight upward through the liquid on the plate. The arrangement, number and size of the holes are design parameters.
Dr Salam Al-Dawery

37. Packings
Packings are passive devices designed to increase the interfacial area for vapour-liquid contact.
They do not cause excessive pressure-drop across a packed section, which is important because a high pressure drop would mean that more energy is required to drive the vapour up the distillation column.
Packed columns are called continuous-contact columns while trayed columns are called staged-contact columns because of the manner in which vapour and liquid are contacted.
Dr Salam Al-Dawery

38. Adsorption The solid adsorbent is usually held in a fixed bed.
Adsorption is a separation process where the fluid is contacted with small particles of a porous solid which selectively adsorbs or complexes with certain components of the feed.
The solid adsorbent is usually held in a fixed bed.
Dr Salam Al-Dawery

39. Drying
Removal of water (usually small amounts) or other liquid from a solid material to reduce the content of residual liquid to an acceptable low value
Water may be removed by presses or centrifuge (mechanical) or thermally by vaporization
Dr Salam Al-Dawery

40. Agitation and Mixing Induced motion of a material in a container
Random distribution into and through one another, of two or more initially separate phases.
Dr Salam Al-Dawery

41. Fluidization Is a particle-fluid interaction
When a gas or liquid is passed upward through a bed of particles, at a certain velocity the particles will become suspended in the fluid.
Types: Fixed Bed and
Fluidized Bed
Dr Salam Al-Dawery

42. Filtration1/2
The removal of solid particles from a fluid by passing the fluid through a filtering medium on which the solids are deposited.
Dr Salam Al-Dawery

43. Filtration2/2
Dr Salam Al-Dawery

44. Crystallization
The formation of solid particles within a homogenous phase
Formation of solid particles in a vapour, solidification from a liquid melt, or crystallization from liquid solution
A variety of materials are marketed in crystallized form.
Many are vacuum units where adiabatic evaporative cooling induced super-saturation.
Dr Salam Al-Dawery

45. Centrifugation1/2
Many given particles settle under gravitational force at a fixed maximum rate
To increase the settling rate we replace the force of gravity by a much stronger centrifugal force.
More effective than gravity separators because they will separate fine drops and particles and are much smaller in size for a given capacity.
Cyclones: used for solids removal from gas:
Dr Salam Al-Dawery

46. Centrifugation2/2
cyclone
Dr Salam Al-Dawery

47. Materials handling Materials handling Classification: Comminution
Characterization of solids by size and shape
Done in a series of standard screens or woven wire test sieves arranged serially on a stack, with the smallest mesh on the bottom and the largest on top.
Comminution
Size reduction of solid particles , for example, chunks of coke must be reduced to workable size
Compression, impact, attrition (rubbing) or cutting, crushers and grinders are good examples.
Dr Salam Al-Dawery

48. Reactors 1/4
While not a unit operation, reactors are essential process operations
They are identified on flowsheets by the type of vessel and their flow:
Batch reactor
Continuous stirred tank reactor (CSTR)
plug flow or tubular reactor
Dr Salam Al-Dawery

49. Reactors 2/4 Batch reactor
A tank or vessel where reactants have been placed and products are removed
There is no inflow or outflow of reactants or products.
Dr Salam Al-Dawery

50. Reactors 3/4 Continuous Stirred Tank Reactor (CSTR)
Run at steady state (ie no accumulation)
Very well mixed
Modelled as having no spatial variations in concentration, temperature, pH or reaction rate in the vessel
T an C are identical everywhere in the vessel, they are the same at the exit as in the tank.
Dr Salam Al-Dawery

51. Reactors 4/4 Plug Flow or Tubular Reactor
Consists of a cylindrical pipe
Assume the flow is highly turbulent and there is no radial variation in concentration.
Dr Salam Al-Dawery

52. End of Chapter 1