1
Introduction
1.1 Definition of Chemical Engineering
Chemical engineering is a branch of engineering concerned with the conceptual, front-end and detailed design, construction, and operation of
technologies and plants that perform chemical reactions to solve practical
problems or make useful products or provide chemical and environmental
solutions for many societal needs. It deals mainly with industrial or commercial processing to produce value-added products from raw materials.
The processing of organic (crude oils, natural gas, lumber), inorganic (air,
ores, salts) and biological (starches, fats, cellulose) materials into a wide
range of useful commodity products, such as plastics, fuels, pharmaceuticals, chemical additives, fibers, fertilizers and foods, is carried out in a
controlled process within a framework of environmental sustainability and
concern for worker and public safety. Emphasis is on the concept, design,
construction and economic operation of equipment that effect the chemical changes and on related research and development.
Figure 1.1.1 Crude Oil Refinery (Image sourced at http://www.filtsep.com/view/16678/
energy-materials-processing-filtration-and-the-fuels-of-the-future/, 2014).
Uche Nnaji (ed.) Introduction to Chemical Engineering: For Chemical Engineers and Students, (1–36)
© 2019 Scrivener Publishing LLC
1
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Introduction to Chemical Engineering
Chemical engineering differs from other types of engineering in the application of knowledge of chemistry and biochemistry, in addition to other
chemical engineering principles. The discipline generally involves researching, planning, development, evaluation and operation of chemical, biochemical or physical plants and processes; pollution control systems, changes in
composition, heat content; analysis of chemical reactions that take place in
mixtures; determination of methodologies for the systematic design, control
and analysis of processes, evaluating economics, safety and state of aggregation of materials. It also involves analysis of forces that act on matter that leads
to the formation of new or conventional chemical materials and products.
Slin’ko (2003) [1] elaborates that chemical engineering, as a rule, deals
with nonequilibrium chemical engineering systems. Consequently, the analysis and description of such systems present substantial difficulties, which
become fundamental as the number of structural elements is increased and
the system regresses from equilibrium. The technical aspects of chemical
Table 1.1.1 Systems of Interest to Chemical Engineering.
Products
Products of interest to chemical engineering include
various types of commodity or specialty polymers;
pharmaceuticals; a broad array of inorganic, ceramic,
or composite materials; chemicals and materials for
personal care products (e.g., cellular phones, optic
fiber communication networks), medical products, or
automobiles; diagnostic devices; drug delivery systems; and
others.
Processes for
making
products
Processes of interest to chemical engineering include a large
variety of industrial manufacturing systems used for the
production of chemicals and materials (e.g., chemical
plants, petrochemical plants, multipurpose pharmaceutical
plants, microelectronics fabrication facilities, food
processing plants, biomass to fuel conversion plants);
ecological subsystems such as the atmosphere; the human
body in its entirety and its parts; and energy devices such as
batteries and fuel cells.
Applications
of interest
Applications of interest to chemical engineering include
monitoring and control of air pollution; extraction of
fossil energy; life-cycle analysis, design, and production of
“green” or sustainable products; diagnostic devices; drug
targeting and delivery systems; combustion systems; solar
energy; and many others.
Introduction 3
engineering, hence, revolve around managing the behavior of materials and
chemical reactions in a closely controlled system—this means predicting
and manipulating chemical or biochemical process parameters such as compositions, temperatures, flow rates, and pressures of solids, liquids and gases.
Therefore, another way to explain chemical engineering is to state that
it is a discipline that deals with the engineering aspects of chemical and
biological systems of interest. The special focus within the discipline on
process engineering cultivates a systems perspective that makes chemical
engineers extremely versatile and capable of handling a wide spectrum
of technical problems. Systems of interest most often include products,
processes for making them, and applications for using them. Beyond
designing, manufacturing, and using products, chemical engineering also
includes finding new ways to measure, effectively analyze, and possibly
redesign complex systems involving chemical and biological processes.
1.1.2 Chemical Engineers
A comprehensive description of the chemical engineer may be to say that
he or she is the engineer that designs both products and processes, plans
and constructs process hardware, manages operations of processes and
researches the solutions to environmental problems. Hence, chemical engineers can be directly involved in research and development and responsible for the design, construction and operation of hardware and processes
in varied areas such as energy, biomedicine, electronics, food engineering/
technology, materials, biotechnology, the environment and so on. Details
of these areas of expertise are treated in Chapter 3.
Figure 1.1.2 Chemical Engineers maintain and run plants.
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Introduction to Chemical Engineering
Following completion of process and equipment design, chemical engineers, in addition, remain on hand at a production facility to solve problems that occur as the processes continue. When changes occur that upset
a running system, chemical engineers analyze samples from the system,
looking at parameters such as flow rates, temperatures and pressures to
determine where the problem exists. They also work on expanding projects, evaluating new or alternative equipment, and improving existing
equipment and processes. Meeting safety, health, and environmental regulations is also a large part of a chemical engineer’s work life.
By way of example, the work of the process/chemical engineer can
involve any of the following:
• Designing a process to produce or refine a given chemical or
biochemical product through all the stages from feedstock
to output of the finished product.
• Designing or sizing the various pieces of equipment or process units which make up this process.
• Once a production process is operational, process/chemical
engineers can be responsible for managing the production
process, improving the efficiency and safety of the process;
ensuring products meet the designed specifications, quality
standards are maintained, products are produced in a way
there can be no harm to the environment; ensuring that
the product is produced in a cost-effective manner; seeking
ways of optimizing the production process by minimizing
cost, recycling energy, reducing man-hours and recovering
and utilizing by-products.
Generally, success of a large-scale chemical production and the quality
of the products are a function of the elaborate but economical design of the
process and equipment and precise control of the production processes by
chemical engineers.
Services provided by chemical engineers in a chemical process industry
[4] are summarized in Table 1.1.2.
In conclusion, chemical engineers concern themselves with the design
of chemical processes and the processing facility where raw materials are
turned into valuable products. The necessary skills for chemical engineers
encompass all aspects of design, research, management, construction, testing, problem solving (troubleshooting), scale-up, operation, control, and
optimization, and require a detailed understanding of the various unit
operations and unit processes. The chemical engineer adopts an integrated
Introduction 5
Figure 1.1.3 Chemical engineers design, construct and operate plants (Image sourced at:
http://en.wikipedia.org/wiki/Chemical_engineering, 2014).
Table 1.1.2 Services Provided by Chemical Engineers for Process Industries.
• Feasibility Studies
• Process Synthesis Designs
• FEED Studies
• Process Technical and Economic
Evaluation
• Relief/Flare/Vent Studies
• Basic Engineering Design Packages
• Pilot Plant Design, Evaluation and
Scale-up
• Greenfield Plant Designs
• Plant Commissioning
• Plant Retrofits
• Process Modeling and Simulation
• Process Equipment Specifications
• Process and Equipment
Troubleshooting
• Cost Estimates
• Chemical Engineering/Technical
Management
• Process Planning and Scheduling
• Research and Development
• Process and Product Development
• Plant Investment Due Diligence
Evaluation
• Process Design
• Process Evaluations
• Throughput Debottlenecking
• Process Optimization Studies
• Energy Conservation Projects
• Independent Design Verification
• Process Reliability Studies
• Existing Equipment Utilization
Studies
• Technical Bid Reviews
• Emissions Limits Process
Compliance
• Product Specification
Improvement Evaluation
• Plant Operation Support
• Plant Construction Support
• Process Safety Management
• Turnaround Support
• Risk Management Program
Development
• Process Hazard Analysis
Facilitation
• Hazards and Operability Studies
(HAZOPs)
• Operations Training
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Introduction to Chemical Engineering
approach to problem solving, applying his or her specialized knowledge in
chemistry, mathematics, physics, kinetics, transport phenomena, reactor
and other equipment design, separation techniques and thermodynamics
to the study of dynamic systems and processes.
1.2 It is the Broadest Branch of Engineering
Chemical engineers are sometimes called “universal engineers” because
their scientific and technical mastery are wide. Chemical engineering is
broader in scope than the other branches of engineering because it draws
on the two main engineering basics: mathematics and physics, as well as
chemistry and other life sciences, whereas the other branches are based
on only the first two. The discipline is essential in fields where processes
involve the chemical or physical transformation of matter. It began as a
discipline tied to a single industry, the petrochemical industry, but today it
is the discipline that interacts with a broad range of industries and technologies. The scope and versatility of a chemical engineering program of study
will continue to open many new opportunities for chemical engineers in
the future. Chemical engineers have been trained to think at molecular
level—in terms of chemical, biological, and physical transformations, as
well as at the process and system level. Thus, innovations have moved from
macroscopic toward microscopic, and to the nano and molecular scales.
The focus of chemical engineering on molecular transformations, quantitative analysis, processes and multiscale treatment of problems makes
the discipline exceptional and provides an ideal basis for productive interactions with a wide range of other science and engineering disciplines at
boundaries that are among the most exhilarating technology areas of our
time. The field synthesizes knowledge from several disciplines (multidisciplinary) and interacts with researchers from multiple disciplines (interdisciplinary) as illustrated in Figure 1.4.3. The engineering discipline has
demonstrated a unique ability to synthesis diverse forms of knowledge
from applied sciences and other engineering disciplines into cohesive and
effective solutions for many societal needs. This integrative capacity is at
the nucleus of the discipline’s reason for existence and is its most unique
characteristics.
A study group in the US reports that chemical sciences and engineering
together have resulted in the most enabling science/technology combination to underpin technology development in every industrial sector.
Introduction 7
No other technology is as prevalent and influential as chemical technology in all industries. The field is a lifelong learning experience because it
is constantly evolving. While the principles learned in college and university will always be a vital part of a chemical engineer’s repertoire (range of
work), chemical engineering can change with new discoveries. Given the
spread of the discipline, chemical engineers later in their careers might find
themselves working in an industry that did not exist when they graduated.
1.3 Chemical Engineering – a General Purpose
Technology
Indeed, a discipline that provides the concepts and the methodologies to
generate new or improved technologies over a wide range of downstream
economic activity may be thought of as an even purer or higher-order, of
General-Purpose-Technology (GPT) [5]. This should not be contentious.
A steam engine or a dynamo is not a technology; they are examples of
tangible capital equipment. “Steam” or “electricity”, which means bodies
of knowledge about how to produce steam or electricity, respectively, and
to use them as sources of power or light, in steam engines or dynamos,
are technologies. Similarly, chemical engineering is a body of knowledge about the design of certain technologies. More specifically chemical
engineering is a body of knowledge about the design of process plants to
produce chemical or other products whose production involves chemical
transformations. Chemical engineering has been considered a GPT since
it provides essential guidance to the design of a very wide range of plants.
Furthermore, there has been both a vertical and horizontal dimension to
the outcomes that were generated. The emergence of chemical engineering
meant that downstream sectors experienced lower invention costs. But, in
addition, there was a powerful horizontal outcome, in the sense that the
vast market for petroleum has shaped the development of petrochemicals
through the intermediation of chemical engineering.
1.4 Relationship Between Chemical Engineering
and the Science of Chemistry
Chemistry is the branch of natural science dealing with the composition
of substances and their properties and reactions while engineering is the
application of science to commerce or industry. Hence, chemical engineering is the use of knowledge about properties and reactions (chemical
8
Introduction to Chemical Engineering
knowledge), in addition to other scientific knowledge, to solve practical,
real-world problems. To understand the relationship between chemical
engineering and the science of chemistry, it is necessary to deal with a
widely held view that chemical engineering, like other engineering disciplines, is simply applied science—in this case applied chemistry. Hence,
the design and construction of plants dedicated to large-scale chemical
processing activities entail an entirely different set of activities and capabilities than those that generate the new chemical entities. This activity
begins with laboratory experiment and is followed by implementation of
the technology to full-scale production. Such activities as mixing, heating,
and contaminant control, which can be carried out with great precision in
the laboratory, are immensely more difficult to handle in large-scale operations. By applying critical variables discovered during laboratory experiments, chemical engineers typically anticipate and proffer solutions to
scale up problems. Chemical engineers are trained to work quantitatively,
using data to support plant design; for example, the number of theoretical
plates can affect batch distillations.
Chemical engineers do not have as much laboratory flexibility but can
be equally creative through hypothesis, prediction and use of scenarios.
[6] Ordinary mixing which is carried out in laboratories using laboratory
vessels and equipment becomes a complex science when performed during
scale up in stirred tanks. This operation is affected by many equipmentand process-related parameters such as type of mixer, agitator speeds
(1000rpm) and/or specific mixing duty the process requires.
Chemical engineers design processes to ensure the most economical
operation. Therefore, economic considerations must obviously play a critical role in the design process. This means that the entire production chain
must be planned and controlled for costs. Cost or economic considerations
become decisive in an industrial context, and cost considerations are intimately connected to decisions concerning optimal scale plant. Practitioners
in this field of engineering have been much more deeply involved in dealing with cost considerations than other engineering professions. This is an
interesting feature of chemical engineering. Thus, when a new chemical
entity is discovered, an entirely new question, one that is distant from the
scientific context of the laboratory, surfaces. How does one go about producing it? A chemical process plant is far from a scaled-up version of the
original laboratory equipment.
A simple, multiple enlargement of the dimensions of small-scale experimental equipment would be likely to yield disastrous results.
Introduction 9
Experimental equipment may have been made of glass or porcelain. A
manufacturing plant will definitely have to be constructed of very different
materials. Producing a given useful product by the ton is very different
from producing by the ounce. This really is what accounts for the unique
importance of a pilot plant, which may be thought of as a device for translating the findings of laboratory research into technically viable and economically efficient large-scale production process.
The translation (of laboratory findings), on the contrary, requires
competences that are unlikely to exist at the experimental research
level – these include a knowledge of mechanical engineering, chemistry and physics and an understanding of the underlying economics of
likely alternative engineering approaches.
Chemical Engineering
Figure 1.4.1 Chemical Engineering Illustration (Image sourced at University of Pretoria
Chemical Engineering Department Website: sitefiles/image/44/2063/chemeng_en.jpg, 2017).
Basically, chemistry aims to realize the required functions by synthesizing new materials, and this results in increasing the number of chemical
compounds, but chemical engineering can reduce the number of chemical elements by controlling the shape and nanostructure of materials [8].
Hence, science mainly focuses on the useful product to make, and technology and engineering develops how to make it.
Also, a chemical engineer can both simplify and complicate “showcase” reactions for an economic advantage. Consequently, apart from
scaling-up a laboratory finding by technical means, chemical engineers
also engineer a system that may improve reaction efficiency. For example, operating at a higher pressure or temperature makes several reactions
easier; ammonia, for example, is simply produced from its component
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Introduction to Chemical Engineering
elements in a high-pressure reactor. On the other hand, reactions with a
low yield can be recycled continuously, which would be complex, strenuous work if done by hand in the laboratory. It is not unusual to build
6-step, or even 12-step evaporators to reuse the vaporization energy for an
economic advantage. In contrast, laboratory chemists evaporate samples
in a single step.
However, chemistry brings chemical engineers and chemists together.
This is because a chemical process is dependent on the intrinsic chemistry,
which is independent of scale. Thus, whether a molecule is in a 15ml flask
or a 20m3 vessel, it will still behave as determined by its surroundings.
1.4.1 Chemical Engineers Take Chemistry Out
of the Laboratory and Into the World
The principles of chemistry, mathematics, and physics are applied by chemical engineers to design and operate large-scale chemical manufacturing
processes. They translate processes developed in the laboratory and adapt
production methods from the small scale in the laboratory into large-scale
practical applications for the production of such products as chemicals,
pharmaceuticals, plastics, medicines, detergents, and fuels; design plants
to maximize yield and minimize costs; evaluate plant operations for performance and product quality.
Chemistry
Engineering design
Large Scale Production
Figure 1.4.2 From Chemistry Laboratory to Large-Scale Production.
In the chemical manufacturing sector, the chemist may be the main
agent in the development of new products, but the design of the industrial manufacturing technology for new products, as well as improving the
technologies for manufacturing old products, is the chemical engineers’
Introduction 11
expertise. Hence, they develop technologies that will utilize network of
organizations to take processes from chemists’ ideas into production.
Imagine designing a chemical plant that produces 2.5*105 metric tonnes
per annum of 4-hydroxy-2-butanone by dehydrogenation of 2, 4-hydroxy
butanol. This scale up requires development of a technology (the process)
which will include various large equipment (hardware) which design also
will involve applying engineering principles. Take for example, a chemical
engineer who works in an area that produces hexamethylene diamine—a
molecule used in the production of nylon. His or her main work may
involve applying chemists’ findings to large-scale production. Hence, this
engineer takes up what a chemist does—synthesize a small amount of a
material—and scales it up to the level of producing several hundred tons
per day. This process includes determining how to separate the desired
product from its impurities or by-products. Other activities of the engineer may focus on chemical kinetics, fluid flow and heat transfer on a large
scale—techniques that do not pose problem with smaller reactions in beakers. Consequently, the engineer would ultimately design equipment that
will accommodate these concerns.
Design, Construction and
Operation of Plants for large
scale Production of Laboratory
Findings
Chemical
Engineers
Laboratory
Research/Findings
Discovery
Chemists
Biochemists
Pharmacists
Microbiologists
Figure 1.4.3 Relationship between Chemical Engineers and other Scientists.
Other
Natural
Scientists
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Introduction to Chemical Engineering
Figure 1.4.4 A Chemist Working in the Laboratory (Image sourced at: http://bobtrade.
net/more-details/pages-under-slider/popular-courses/chemical-engineering/, 2012).
Figure 1.4.5 A Chemical Engineer in the Plant.
1.5 Historical Development of Chemical Engineering
The key events and activities of some people that led to the development
and emergence of chemical engineering are succinctly discussed in this
section. The chemical engineering discipline unarguably can be said to
have evolved systematically in the following way:
Introduction 13
1900
1925
1950
1975
• Industrial Chemistry and Mechanical Engineering
• Unit Operations
• Chemical Engineering Science
• Chemical Systems Engineering
Figure 1.5.1 Evolution of Chemical Engineering.
1.5.1 Industrial Chemistry and Mechanical Engineering
Sulfuric Acid Production
The relationship between chemistry and chemical engineering has been
established in section 1.4 of this chapter. Thus, it will not be surprising
that development of chemical engineering is being traced to industrial
chemistry. Industrial chemistry was being practiced in the 1800s but it was
not until the 1880s that engineering rudiments required to control chemical processes were being recognized as a distinct professional activity.
Historians agree that chemical engineering was developed in the twentieth century. By this time, organic chemistry was almost a century old, and
inorganic chemistry was far older.
Sulfuric acid was first among certain chemicals that became necessary
to sustain economic growth in the eighteenth century as the Industrial
Revolution soared. In fact, a nation’s industrial might could be gauged solely
by the vigor of its sulfuric acid industry. Hence the need for optimal production of sulfuric acid arose. The Lead-Chamber Method, which required
air, water, sulfur dioxide, a nitrate, and a large lead container, was being
used (since 1749) to create sulfuric acid. Nitrate was always the most expensive because they are lost to the atmosphere at the final stage of the process
in the form of nitric oxide; hence, necessitating a make-up stream of fresh
nitrate. This extra nitrate had to be imported in the form of sodium nitrate
from Chile. John Glover helped solve this problem in 1859, by introducing
a mass transfer tower to recover the nitrate being lost to the atmosphere.
Sulfuric acid at the stage where it still contains nitrates was trickled downward against upward flowing burner gases in the tower. By so doing, the
nitric oxide could be reused when the flowing gases which had previously
absorbed lost nitric oxide were recycled back into the lead chamber.
Leblanc and Solvay Process
Nicolas Leblanc invented a process for the production of soda ash (sodium
carbonate, Na2CO3) and potash (potassium carbonate, K2CO3), collectively
called alkali. The process became known as Le Blanc process. These Alkali
14
Introduction to Chemical Engineering
compounds were used in a wide range of products including glass, soap,
and textiles and were as a result in high demand. The process yields undesirable by-gaseous products. Problems caused to the environment by the
by-gaseous products (calcium sulfide), health effects, and elaborate and
often complex engineering efforts ushered in the Solvay process (in 1873)
which replaced Leblanc’s method for producing Alkali. Ernest Solvay
invented this process.
George E. Davis
After 1850, “chemical engineering” describing the use of mechanical equipment in chemical industries became common vocabulary in England.
George Davis is regarded as the founding father of chemical engineering by
many authors. He was a heretofore unremarkable Alkali Inspector from the
Midlands region of England. His career in chemistry started in a chemical
industry in Manchester. He then worked as a chemist at Brearley and Sons
for three years; then as an inspector for the Alkali Act of 1863. In 1872 he was
employed as manager at the Lichfield chemical company in Staffordshire.
Notable in his work at the time is the tallest chimney in the UK, with a height
of more than 200 feet (61m). In 1880 George Davis acted upon ideas of a
discipline of chemical engineering and proposed the formation of a “Society
of Chemical Engineers”. The attempt was unsuccessful, yet he continued
to boldly promote chemical engineering. In 1884 Davis became an independent consultant applying and synthesizing the chemical knowledge he
had accumulated over the years. As an industrial consultant and inspector,
Davis visited a great variety of chemical processing plants. He was keen to
identify broad features in common to all chemical factories. Hence, he published in 1887 a series of 12 lectures on chemical engineering, at Manchester
Technical School (which became University of Manchester Institute of
Science and Technology). He proposed a chemical engineering course which
would be organized around individual chemical operations, later to be called
“unit operations.” Davis explored these operations empirically and presented
operating practices in use by the British chemical industry.
Consequently, some felt his lectures simply shared English know-how with
the rest of the world. His effort once more fizzled in Britain but his dream
was eventually established in America. One would assume here that Davis
failed in establishing chemical engineering in British universities because to
develop a discipline emphasizing general principles was more suited to universities than commercial firms. Academic and government attitudes therefore may have played a role. Another suggested reason why Davis’s proposal
was not fully accepted in Britain was because Henry Edward Armstrong,
who started a degree course in chemical engineering three years earlier,
Introduction 15
George Davis
Fritz Haber
Carl Bosch
Figure 1.5.2 Men that Steered Chemical Engineering Discipline (Photo Courtesy of BASF
at: https://www.thechemicalengineer.com, 2017).
could not make it. Armstrong’s course did not succeed because employers
would rather employ a chemist and a mechanical engineer than a chemical
engineer, at that time. Davis expanded on the 12 lectures, and 14 years later
authored a book, A Handbook of Chemical Engineering, published in 1901.
Emergence of Chemical Engineering Degree
Lewis Norton, a chemistry professor at the Massachusetts Institute of
Technology (MIT) in 1888 initiated the first four-year bachelor program
in chemical engineering entitled “Course X” (ten); just a few months after
the lectures of George Davis. Norton’s course was contemporaneous and
simply merged chemistry and engineering subjects (mechanical engineering). University of Pennsylvania and Tulane University and other colleges
soon followed MIT’s lead by initiating their own four-year programs.
However, at this early stage, chemical engineering was tailored to fulfill
the needs of the chemical industry. Practitioners of chemical engineering
at the time faced difficulty convincing engineers that they were engineers
and chemists that they were not chemists. In 1905, unit operations was
introduced into the course by William Hultz Walker and by the 1920s this
had become an important aspect of the discipline of chemical engineering
at MIT, other US universities and Imperial college London. The discipline
gradually began to metamorphose into an independent profession when
the American Institute of Chemical Engineers (AIChE) was formed in
1908. The AIChE defined chemical engineering to be a separate science
which is based on unit operations. During the First World War, the British
army faced shortage of munition (stock of shells) in the Great Shell crisis.
It was at this time that Kenneth Bingham Quinan designed and led the
large-scale manufacture of efficient (high) explosives and propellants. The
success of this effort eventually gave rise to formation of the Institution of
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Introduction to Chemical Engineering
Chemical Engineers (IChemE) in Britain in 1922. Quinan later became the
first vice president of the institution.
Figure 1.5.3 Kenneth Bingham Quinan (Picture sourced at: https://www.thechemicalengi
neer.com/features/cewctw-keith-bingham-quinan-and-colleagues-an-explosive-start, 2017).
But by the 1940s, it had become obvious that unit operations alone were
not sufficient to develop chemical reactors; hence transport phenomena,
process system engineering and other novel concepts started to gain much
focus. Thermodynamics, which included properties of gases and liquids, and
applications of both first and second laws, were also introduced at the time.
Furthermore, it is worth stating that, surprisingly, chemical engineering did
not come to Germany early, yet industrial chemists and mechanical engineers
in that country had been having strong collaboration, leading to invention and
industrialization of the Haber-Bosch process in early 1908 to 1911 [10]. Fritz
Haber, who was a chemist, invented a method for synthesizing ammonia and
this requires temperatures up to 500oC and pressures up to 1000 atmospheres
[11]. Because such high temperature and pressure were enormously difficult
to attain on the industrial scale, his invention might have remained a laboratory curiosity. Hence, Carl Bosch, a mechanical engineer, scaled up the process
leading to ammonia production. Both received the Nobel Prize award.
The chemical engineering degree program at the time was developed to
fulfill the need of chemical process industries (CPI). An academic curriculum
was established to train students that can fit into the industry immediately
after graduation, to serve this need. Meanwhile, competition amongst various
chemical companies around the world was intense. Some dishonest individuals even did many unethical acts, which included trying to outdo one another
Introduction 17
by bribing agents to contaminate others’ products. Yet this did not provide the
much-needed competitive edge. Competition, however, contributed to reshaping the chemical engineering curriculum. By this time companies started
thinking of ways of lowering cost through optimizing production process to
beat competition. This led to innovative ideas such as continuous production process, by-product recycling, and other critical optimization techniques
and automatic controls to continuous processing in many chemical industries. At this stage, an entirely new generation of engineering practitioners
that had distinct dexterity was born. CPI’s would now have the opportunity
of employing chemical engineering graduates over mechanical engineering
or chemistry graduates. Up until date, process optimization remains the core
drive of every chemical process engineer. Success of these innovative ideas
led to some CPI’s establishing a dedicated research and development (R&D)
department for continuous study of more ways of lowering cost. For these
companies that are inclined to innovation, another breed of chemical engineering graduate is required. A kind of chemical engineering science graduates and chemical engineering technology graduates were hence born. Over
time academic research has had a strong push toward science, largely due to
the emergence of areas like nanotechnology and biotechnology, which consequently has caused some disconnect between academia and industry. The
evolution of chemical engineering is summarized in Table 1.5.1.
Table 1.5.1 Chronological History of the Emergence of Chemical Engineering.
1859
Sulfuric Acid
Production
John Glover helped solve problem of
losing nitrate to the atmosphere, by
introducing a mass transfer tower to
recover the nitrate.
1873
Le Blanc and
Solvay Process
Ernest Solvay invented a process that
helped solve the problem caused to
the environment by the by-gaseous
products from Nicolas Leblanc’s process
for alkali production.
1880
George Davis
George Davis, regarded as the founding
father of chemical engineering, acted
upon ideas of a discipline of chemical
engineering and proposed the formation
of a “Society of Chemical Engineers”.
The attempt was unsuccessful.
(Continued)
18
Introduction to Chemical Engineering
Table 1.5.1 Chronological History of the Emergence of Chemical Engineering.
(Continued)
1884
George Davis
George Davis published in 1887 a series
of 12 lectures on chemical engineering,
at Manchester Technical School (which
became University of Manchester
Institute of Science and Technology).
He proposed a chemical engineering
course which would be organized
around individual chemical operations,
later to be called “unit operations.” Davis
explored these operations empirically
and presented operating practices in
use by the British chemical industry.
This dream fizzled in Britain but was
eventually established in America.
1888
Lewis Norton
Lewis Norton, a chemistry professor
at the Massachusetts Institute of
Technology (MIT) initiated the first
four-year bachelor program in chemical
engineering entitled “Course X” (ten);
just a few months after the lectures
of George Davis. Norton’s course was
contemporaneous and simply merged
chemistry and engineering subjects.
1908
AIChE
American Institute of Chemical Engineers
(AIChE) was formed.
1908-1911
Haber-Bosch
Process
In Germany, Carl Bosch, a mechanical
engineer, scaled up a process developed
by Fritz Haber, a chemist, leading to
ammonia production. Both received
the Nobel Prize for their work
in overcoming the chemical and
engineering problems posed by the use
of large-scale, continuous-flow, highpressure technology.
1916
Arthur Dehon
Little
In America, Arthur Little propounded the
concept of “unit operations” to explain
industrial chemistry processes.
(Continued)
Introduction 19
Table 1.5.1 Chronological History of the Emergence of Chemical Engineering.
(Continued)
1922
IChemE
Institution of Chemical Engineers
(IChemE, Britain) was formed.
1924
William H.
Walker, Warren
K. Lewis and
William H.
McAdams
William H. Walker, Warren K. Lewis and
William H. McAdams wrote the book,
The Principles of Chemical Engineering.
They explained the variety of chemical
industries processes which follow
the same physical laws and summed
up these similar processes into unit
operations. This became the standard
textbook for chemical engineering for
decades.
1940s
Transport
Phenomena,
Process System
Engineering
and others
It became obvious that unit operations
alone are not sufficient to develop
chemical reactors, hence transport
phenomena, process system
engineering and other novel concepts
started to gain much focus.
1.5.2 Unit Operations
Historically, the chemical engineering concept systematically evolved
from industrial chemistry to unit operations, then to chemical engineering science and then to chemical systems engineering. Effectively, the
emergence of distinct knowledge for the discipline began when Arthur D.
Little started the concept of unit operations in the early nineteenth century. He understood that the principles are the same for different industrial processes. Hence, various unit operations were being identified and
developed. For example, the physical separations such as distillation,
absorption, and extraction, in which the principles of mass transfer, fluid
dynamics, and heat transfer were combined in equipment design (process unit), were developed. The concept of unit operation has remained
throughout the phase of chemical engineering growth and has even been
used to understand the way the human body functions. The chemical and
physical aspects of chemical engineering are known as unit processes and
unit operations, respectively.
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Introduction to Chemical Engineering
In 1923, William H. Walker, Warren K. Lewis and William H. McAdams
leveraged on the work of Arthur D. Little and wrote the book The Principles
of Chemical Engineering. The authors explained in the book that unit
operation follows the same physical laws and may be used in all chemical
industries. The unit operations thus became the fundamental principles
of chemical engineering. Unit operations method was then being used
to tackle the fundamental problems of the quantitative control of large
masses of material in reaction and to design cost-effective industrial-scale
processes for chemical reactions. The knowledge is that industrial chemical-manufacturing processes can be resolved into a relatively few units,
each of which has a definite function and each of which is used repeatedly
in different kinds of processes. The unit operations are steps like filtration
and clarification, heat exchange, distillation, screening, magnetic separation, and flotation. They can also include mechanical operations such as
mixing or crushing, or thermal operations such as liquefaction or refrigeration. A typical process unit is shown in Figure 1.5.4. Chemical engineering unit operations consist of five classes:
Mechanical processes
• including crushing and pulverization, solids
transportation, screening and sieving
Mass transfer processes
• including distillation, gas absorption,
extraction, adsorption, drying
Fluid flow processes
• including filtration, fluids transportation,
solids fluidization
Thermodynamic processes
• including refrigeration, gas liquefaction
Heat transfer processes
• including condensation, evaporation
Chemical engineering unit operations also fall into the following categories:
Combination
• Mixing
Separation
• Distillation
Reaction
• Chemical Reaction
Introduction 21
The following are some chemical engineering unit operations and
techniques being applied in chemical process industries:
Table 1.5.2 Chemical Engineering Unit Operations and Techniques.
Petrochemical
Solution polymerizations
Fluid bed polymerizations
Condensation polymerizations
Specialty polymers and monomers recovery, etc.
Pharmaceutical
Separation
Chiral selectivity
Parallel synthesis
Multi-step processing, etc.
Laboratory
Catalyst development
Multi-purpose mini-plants
Supercritical wet oxidation
Batch to continuous flow scale-up, etc.
Food
Solids blending
Starch processing
Supercritical extractions
Hydrogenation/dehydrogenation, etc.
Energy
Alternative fuel
Syngas/Fuel cell
Supercritical processing
Liquefaction/upgrading, etc.
Refining
Reforming
Hydrocracking
Isomerization
Hydrotreating, etc.
Chemical
Amination
Alkylation
Carboxylation
Crystal growth, etc.
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Introduction to Chemical Engineering
Figure 1.5.4 A Process unit of petrochemical plant under construction at Lagos.
1.5.3 Chemical Engineering Science
The so-called engineering science approach in the discipline emerged in
the 1950s and 60s. This is the second paradigm of chemical engineering,
unit operation being the first. (Refer to Figure 1.5.1.) The chemical engineering science involves thinking about those chemical processes very
much like natural scientists do with natural phenomena. Chemical engineers hence treated these processes in the quantitative way and exposed
the laws controlling them in relation with the materials and equipment
concerned in them. Chemical engineering science therefore utilizes
mass, momentum, and energy transfer along with thermodynamics and
chemical kinetics to analyze and improve on “unit operations”, such as
distillation, mixing, and biological processes, and so on. However, the
idea of engineering science was not unique to chemical engineering as
other engineering disciplines also began to incorporate similar ideas to
solve problems in their domain at about the same time. This approach
led to a chemical engineering curriculum, at both the undergraduate
and graduate levels, that is an exceptional blend of chemistry, physics
and mathematics. The chemical engineers educated in this manner could
effectively develop, design and operate complex chemical and refining
processes that typically produced commodity chemicals and a variety
of products derived from petroleum and other feedstocks. Producing
petroleum at large scale provided chemical engineers the opportunity to
Introduction 23
apply their design and problem-solving capabilities that were critical to
the creation of some entirely new industries.
1.5.4 Chemical Systems Engineering
Chemical systems engineering is subdivided into process design, process
control and process operations. The early 1960s saw an explosive growth
period for the chemical process system. Three factors were responsible:
the need for less costly processes due to rapid growth of chemical industry; to optimize production process, a science-based description of the
fundamental phenomena in unit operations became necessary; and the
computer also became necessary to produce more reliable quantitative
description of process units. Hence, by the 1960s chemical engineers could
put mathematical descriptions of reactions, their rates, thermo-physical
properties of pure materials and mixtures, equilibrium and rate processes,
and could integrate these as functions of equipment design parameters and
the process operating conditions.
1.6 Anatomy of a Chemical Engineering Plant
1.6.1 Overview
A chemical or gas plant is an industrial process plant that manufactures (or
otherwise blends or processes) chemicals (gaseous, solid or liquid) or natural gas, usually on a large scale. A chemical or gas plant is usually located
near the source of feedstock or raw materials. For example, petrochemical
plants are usually located adjacent to or near an oil refinery to minimize
transportation costs for the feedstocks produced by the refinery. However,
specialty chemical plants which are usually much smaller are not as sensitive to location. A variety of chemicals can be produced from one chemical plant. Safety is a major concern in chemicals or gas processing plant.
High safety standards are maintained as mistakes at a chemical plant can
be very dangerous and chemical plants are susceptible to acts of sabotage
and terrorism. A chemical plant can become a chemical bomb as in the
case of DuPont Yerkes chemical plant explosion, T2 laboratories explosion
(US), BP refinery explosion, and so on. Chemical plants, consequently, are
usually required to undergo regular safety checks to ensure that the plant is
operating safely, and the facilities have far-reaching security to protect the
plant from external threats.
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Introduction to Chemical Engineering
Typical productions of chemical and gas plants are:
•
•
•
•
•
•
Pharmaceutical
Agriochemicals
Food & beverages
Sheet Processes
Textiles
Treated and compressed hydrocarbon gases
The overall objective of a chemical, biochemical or gas plant is to create
new material wealth via the physical, chemical or biological transformation and or separation of materials. Chemical plants use special equipment, units, and technology in the processes.
Figure 1.6.1 Inside View of a Gas Processing Plant.
Figure 1.6.2 Front View of a Gas Processing Plant.
Introduction 25
The figure below shows the various features of a process plant. These are
considered in no order in the following sections.
Laboratoryy
Warehouse
and Storage
Power/Electrical
Unit
Pumps,
Piping and
Valves
Fire Fighting
Unit
Atmospheric
Storage
Tanks
Office
Buildings
Anatomy of a Process
Plant
Workshop
and
Lay-down
Area
Process
Units
Fire and
Atmospheric
Ventilation
Process
Control
Figure 1.6.3 Anatomy of a Process Plant.
1.6.2 Process Units
A typical chemical or gas plant has large vessels, equipment or sections
called process units that are interconnected by process piping or other
material-moving equipment which can carry streams of material. The
streams of material in the process piping are usually fluids which can be
gas or liquid and sometimes solids or mixtures of both solids and liquids
such as slurries. Various kinds of unit operations are conducted in different
types of these units. The units may operate at ambient temperature or pressure, but many units operate at higher or lower temperatures or pressures.
Vessels in chemical plants are often cylindrical with rounded ends, with
body thickness which can be suited to hold high pressure. In a chemical
plant, the main unit is known as a reactor; this is where chemical reaction
takes place. Reactants are converted into various kinds of useful outputs in
a chemical reactor. Chemical reactors may be packed beds and may have
solid heterogeneous catalysts which stay in the reactors as fluids move
through. Some can be batch reactors, while some are continuous reactors. Continuous reactors are predominant in a process plant because of
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Introduction to Chemical Engineering
continuous operation. There are other units or subunits in a process plant,
which serve various purposes. They include mixing (including dissolving), separation, drying, heating, cooling, or some combination of these.
Chemical reactors usually have stirring for mixing and heating or cooling
going on in them. Reactions within a reactor can generate or absorb heat
from the surrounding. The heat generated in a reactor can be collected
and used to heat up another unit. When designing plants on a large scale,
heat produced or absorbed by chemical reactions should be considered.
In case of a petroleum refinery, a CO2 boiler is used to generate the steam
that is used to raise the temperature of any unit, where required. For a biochemical plant, the reactor may contain organism cultures for biochemical
processes such as fermentation or enzyme production.
Products or output of a chemical reactor may include a mixture of wanted
and unwanted products. Separator is another unit that does the work of
separated process products into various factions. Separation processes
include filtration, settling (sedimentation), extraction or leaching, distillation, recrystallization or precipitation. Others are reverse osmosis, drying,
and adsorption. For a unit requiring direct heating, a furnace can be erected.
Heat exchangers are used to indirectly heat or cool a process unit.
The amount of primary feedstock or product per unit of time which a
process plant or unit can process is referred to as the capacity of that plant
or unit. For examples, the capacity of a petroleum refinery may be given in
terms of barrels of crude oil refined per day; alternatively, chemical plant
capacity may be given in tons of product produced per day. In actual dayto-day operation, a plant (or unit) will operate at a percentage of its full
capacity.
Figure 1.6.4 Plant Gas Metering unit.
Introduction 27
1.6.3 Process Interconnecting Piping (Pumps, Piping & Valves)
All plant units are usually arranged in a logical manner to take care of
material flow, statutory requirements and good engineering practices.
Feedstock and steams of material in and out of a process unit are carried
through process interconnecting piping. However, final products from one
plant may be intermediate chemicals used as feedstock in another plant for
further processing. For example, some products from an oil refinery may
be used as feedstock in petrochemical plants. These products are transported through process piping.
Figure 1.6.5 Process Interconnecting Piping.
The piping and tubing come in various diameter and sizes. Also, there
are various types of valves for controlling or stopping flow in the pipes.
Pumps are used to move or pressurize liquid and compressors for pressurizing or moving gases. The size and construction of process and utility
piping depend on the type of service, pressure, temperature, and nature of
the products. Vent, drain, and sample connections are provided on piping,
as well as provisions for blanking. The piping can be covered with insulating materials to prevent loss of heat to the surrounding where applicable.
1.6.4 Power/Electrical Unit
A chemical plant is usually powered by gas or a steam-driven electrical system. The interesting aspect of a chemical plant is that it can utilize the heat
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Introduction to Chemical Engineering
generated within a unit of the plant to produce steam which can drive a
steam turbine of a power unit. Also, a gas generated as a by-product can
be used to drive a gas turbine of a power unit. Electricity hence can be produced in the same plant. If exhaust heat from the power generating system
is not needed in the main process, it can be used to drive exhaust steam turbines (dual cycle) for additional efficiency. A gas driven power system and
the power control section of a plant is shown in the following Figure 1.6.6.
Figure 1.6.6 Gas Turbine Power Generator and Power Control Section of a Plant.
1.6.5 Process Laboratory
A process plant also has a laboratory section where various testing, quality checks, researches and analysis are carried out. This is where chemists,
biologists and chemical engineers work together as a team. Analysis done
in the laboratory can include chemical or biochemical analysis or determination of physical properties. Intermediate and final products can also be
routinely analyzed in a process laboratory to ensure quality specifications
are met. Non-routine samples may be taken and analyzed for investigating
plant process problems also.
Figure 1.6.7 Typical Chemical Plant Laboratory (Image Sourced at: chem-eng-net.com, 2012).
Introduction 29
1.6.6 Process Control
In a chemical plant, information gathered automatically from various field
instruments (see Figure 1.6.10) in the plant is used to run and control
operations of the plant. These field instruments—temperature and pressure detectors, level detectors and so on, are linked to a central control
unit. The main function of the control system is to make sure the production, processing and utility systems operate efficiently and safely within
design constraints and alarm limits. Initially, pneumatic controls were
sometimes used. Electrical controls are now common. Very small installations may use hydraulic or pneumatic control systems, but larger plants
with up to 30,000 signals to and from the process require a dedicated control system and building. The purpose of this system is to read values from
a large number of sensors, run programs to monitor the process and control valves, switches and so on, to control the process. Such plant will have
a control room (see Figure 1.6.9) with displays of parameters such as key
temperatures, pressures, fluid flow rates and levels, operating positions of
key valves, pumps and other equipment, and so on.
Some chemical engineering graduates specialize as process control engineers and are employed to work in this unit. Process control is a statistics
and engineering discipline that deals with architecture, mechanism, and
algorithms for controlling the output of a given process.
A commonly used control device called a Programmable Logic Controller
(PLC) is used to read a set of digital and analog inputs, apply a set of logic
statements, and generate a set of analog and digital outputs. For example,
logical statements would compare the setpoint to the input temperature
and determine whether more or less of heating was necessary to keep the
temperature constant. A PLC output would then either open or close the
Figure 1.6.8 An Automation Engineer Inspecting Cable Terminations.
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Introduction to Chemical Engineering
process valve, an incremental amount, depending on whether more or less
process fluid was required. Larger, more complex systems can be controlled
by a Distributed Control System (DCS) or Supervisory Control and Data
Acquisition (SCADA) system. Contemporary distributed control systems
(DCS) connect data from sensors, control systems and operator panels.
Figure 1.6.9 Process Control Room.
In practice, process control systems can be characterized as one or more
of the following forms:
Discrete
• Involves the production of discrete pieces of product. This can be
found in manufacturing, motion and packaging applications. For
example, robotic assembly, such as that are found in automotive
production, can be characterized as discrete process control.
Batch
• Batch processes are generally used to produce a relatively low to
intermediate quantity of product per year. Some applications will
require that definite quantities of raw materials be combined in
precise ways for a period of time to produce an intermediate or
end result. Adhesives and glues for example, normally require
the mixing of raw materials in a heated vessel for a period of
time to form a given quantity of end product. Also, production of
drugs, foods, beverages, etc., are other batch processes. Drugs
for instance, come in drum containers, after production.
Continuous
• Sometimes the materials being processed will be in continuous
motion, undergoing chemical reactions or subjected to
mechanical or heat treatment and uninterrupted in time. This is
known as continuous process. The production of fuels, gas,
chemicals and plastics, are continuous practices. Continuous
chemical processes are used to produce very large quantities of
product per year.
Introduction 31
Pressure
Transmitter
Pressure
Indicator/Gauge
Temperature
Indicator
Shut-down Valve
Pressure
Transmitter
Pressure Control
Valve
Temperature
Transmitter
Level Transmitter
Figure 1.6.10 Process Control Field Instruments.
1.6.7 Storage Tanks
Process plants, furthermore, usually have a location where atmospheric storage and pressure storage tanks are located. These tanks are used in the plant
for storage of crudes, intermediate hydrocarbons (during the process), chemicals, liquid raw materials (feedstock), waste products and intermediate or
final products. Tanks are also provided for fire water, process and treatment
water, petroleum products, acids, additives, and other chemicals. The types,
construction, capacity and location of tanks depend on their use and materials stored in them. Refer to Figure 1.6.11 to see a typical process storage tank
on the top left corner. Storage tanks commonly have control mounted instruments. For example, level indicators are installed on storage tanks to show how
full they are. Some chemical or process engineers specialize just in designing storage tanks. The design may seem simple but often requires application
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Introduction to Chemical Engineering
of very complex engineering techniques. Storage tanks can store hazardous
or highly inflammable substances, hence fluid physio-chemical properties
usually form part of the input data required for process tank design. Poorly
designed storage tank can sheer or rupture or even explode. If the tank contains hazardous or inflammable substances, the incident can be catastrophic.
Stairs are commonly constructed round a storage tank for personnel to reach
the top of the tank for sampling, inspection, or maintenance. The storage tank
can be on a concrete structural foundation or steel structure foundation.
Storage Tank
Gate Valve
Pipe and Vessel
Carrying Steel
Structure
Ball
Valves
Figure 1.6.11 Plant units and valves.
1.6.8 Flare and Atmospheric Ventilation Unit
Another vital section of a process plant, especially a gas processing plant,
is the flare and atmospheric ventilation unit. The purpose of the flare and
vent systems is to provide safe discharge and disposal of vapor (gases) and
liquids resulting from:
• Spill-off flaring from the product stabilization system (for
example, oil condensate).
• Relief of excess pressure caused by process upset conditions
and thermal expansion.
• Depressurization either in response to an emergency situation or as part of a normal operating procedure.
• Venting from equipment operating close to atmospheric
pressure (for example, atmospheric tanks).
Introduction 33
Figure 1.6.12 Flare Unit of a Plant.
For safety reasons a stack is used to elevate the flare. The flare must be
located so that it does not present a hazard to surrounding workers and
facilities and also the neighboring community. In the flare, air may tend
to flow back into a flare stack due to wind or thermal contraction of stack
gases and create an explosion potential. To prevent this, a gas seal is typically installed in the flare stack. The burner tip or flare tip is designed
to give environmentally acceptable combustion of the vent gas over the
flare system’s capacity range. The burner tips are normally proprietary (see
Section 5.2.3.8) in design. Consideration is given to flame stability, ignition
reliability, and noise suppression. Flare system control can be completely
automated and controlled from the central control room or completely
manual. Components of a flare system which can be controlled automatically include the auxiliary gas, steam injection, and the ignition system.
Pressure-relief systems control vapors and liquids that are released by
pressure-relieving mounted devices and blowdowns. Pressure relief is an
automatic, planned release when operating pressure reaches a predetermined level in any of the installed pressure vessels. Blowdown normally
refers to the intentional release of material, such as blowdowns from process unit startups, shutdowns, furnace blowdowns, and emergencies. Also,
vapor depressuring is the rapid removal of vapors from pressure vessels in
case of fire. Rupture disc set at a higher pressure than the relief valve can
be used to accomplish this. Safety relief valves, used for air, steam, and gas
as well as for vapor and liquid, allow the valve to open in proportion to
the increase in pressure over the normal operating pressure. Safety valves
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Introduction to Chemical Engineering
designed primarily to release high volumes of steam usually pop open to
full capacity. The overpressure needed to open liquid-relief valves where
large-volume discharge is not required increases as the valve lifts due to
increased spring resistance. Pilot-operated safety relief valves, with up to
six times the capacity of normal relief valves, are used where tighter sealing
and larger volume discharges are required. Fluids from blowdown piping
and or discharge lines are usually pumped to a knock-out drum separator, where vapor, oil-water separation and recovery take place. After separating the entrained liquid from the vapor, the stream is fed to the flare
unit, where it automatically ignites and burns in the atmosphere. Detailed
design of a flare knock-out drum can be seen in Section 5.4.
In summary, a typical closed pressure release and flare system includes
relief valves and discharge lines from process units, knock-out (KO) drums
to separate vapors and liquids, gas seals for flashback protection, and a flare
and igniter system. Steam may be injected into the flare tip to reduce visible
smoke.
1.6.9 Workshop and Lay-down Area
Chemical plants commonly have a workshop or maintenance facility for
equipment repairs, parts fabrication or for keeping maintenance equipment and tools. Dedicated technicians and workshop manager are assigned
to work in this unit. Also, during plant upgrade, the workshop serves as a
prefabrication space. The lay-down area is a floor or ground area for laying
down components during maintenance. Process units consisting of large
equipment are commonly located in outer areas in the complex site so
that sufficient spaces can be available for their dismantling and installation. This equipment is first kept in a lay-down area before being erected at
the required position. Lay-down areas are usually large enough to contain
mobile cranes of various sizes and capacities, low-bed trucks, and so on.
1.6.10
Office Building and Others
Office buildings are also commonly found in a chemical plant. Plant senior
management, engineers, administrators and others work in office buildings. These buildings are usually noiseproof and fireproof due to the potential noise and fire hazard associated with a typical chemical plant. Other
buildings also exist in a chemical plant such as a clinic, library in some
cases, kitchen and mess, etc. These buildings are usually out away from
process areas.
Introduction 35
Figure 1.6.13 Engineering Office Meeting Room.
Figure 1.6.14 Engineering Design Office.
1.6.11
Warehouse and Storage
Chemical plant feedstocks and products are kept in the storage facility.
Also, procured parts and equipment are stored in the storage area.
1.6.12
Firefighting Unit
Due to the risk of fire in a typical process plant, a firefighting unit is usually
located in chemical or process plants. Men and women firefighters work
in this area. Firefighting vehicles and other fire water reservoir are also
located here, especially in gas processing plants.
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Introduction to Chemical Engineering
1.6.13
Water Generation Unit
Large chemical process plants will commonly have a water generation unit
that will supply the water needed for steam production or process cooling,
portable water for workers, sanitary water, water for humidification, laboratory experiments, and so on.
1.6.14
Waste Treatment and Disposal Unit
A section of typical chemical plant is usually designed for waste collection
and treatment. Every chemical plant generates waste or unwanted products. This makes this unit a very important one. The waste receiving and
treatment unit is a mini chemical process plant. In order to treat effluent
and solid wastes, several unit operations are required. In this era of quest for
sustainability, waste treatment is imperative. This is coupled with increasing pressure from environmental regulatory bodies. Recovered waste
products also add value to the overall benefit of a process plant. Again, to
balance the ecosystem, some wastes are simply treated and re-introduced
into the ecosystem. In some process plants, the wastes are channeled to
another location where a waste treatment plant is constructed. The waste
can be transported via pipeline, by road or sea to this location.
Figure 1.6.15 shows an effluent waste treatment plant recently constructed and commissioned at the out skirt of Port Harcourt, close to the
sea. The plant receives effluent waste disposal from many oil facilities, processes and recovers useful products. The effluent wastes are transported
by sea to this location. Recovered products include a very high-quality oil
known as heavy oil, marine fuel or furnace oil, which is in high demand
globally. The oil is burned in a furnace or boiler for the generation of industrial process heat or used in an engine for the generation of power.
Figure 1.6.15 Effluent waste disposal Plant recently Commissioned in Port Harcourt.