Chemical Engineering for Non-Chemical Engineers

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What Is Chemical Engineering?

There are no doubt numerous dictionary definitions of chemical engineering that exist. Any of these could be unique to the environment being discussed, but all of them will involve the following in some way:

Technology and skills needed to produce a material on a commercially useful scale that involves the use of chemistry either directly or indirectly. This implies that chemistry is being used at a scale that produces materials used in commercial quantities. This definition would include not only the traditional oil, petrochemical, and bulk or specialty chemicals but also the manufacture of such things as vaccines and nuclear materials, which in many cases may be produced in large quantities, but by a government entity without a profit motive, but one based on the welfare of the general public.

Technology and skills needed to study how chemical systems interact with the environment and ecological systems. Chemical engineers serve key roles in government agencies regulating the environment as well as our energy systems. They may also serve in an advisory capacity to government officials regarding energy, environmental, transportation, materials, and consumer policies.

The analysis of natural and biological systems, in part to produce artificial organs. From a chemical engineering standpoint, a heart is a pump, a kidney is a filter, and arteries and veins are pipes. In many schools, the combination of chemical engineering principles with aspects of biology is known as biochemical or biomedical engineering.

The curriculum in all college‐level chemical engineering schools is not necessarily the same, but they would all include these topics in varying degrees of depth:

Thermodynamics. This topic relates to the energy release or consumption during a chemical reaction as well as the basic laws of thermodynamics that are universally studied across all fields of science and engineering. It also involves the study and analysis of the stability of chemical systems and the amount of energy contained within them and the energy released in the formation or decomposition of materials and the conditions under which these changes may occur.

Transport Processes. How fast do fluids flow? Under what conditions? What kind of equipment is required to move gases and liquids? How much energy is used? How fast does heat move from a hot fluid to a cold fluid inside a heat exchanger? What properties of the liquids and gases affect this rate? What affects the rate at which different materials mix, equilibrate, and transfer between phases? What gas, liquid, and solid properties are important? How much energy is required? Materials do not equilibrate by themselves. There is always a driving force such as a pressure difference, a temperature difference, or a concentration difference. Chemical engineers study these processes, their rates, and what affects them.

Reaction Engineering and Reactive Chemicals. Chemical reaction rates vary a great deal. Some occur almost instantaneously (acid/base reactions), while others may take hours or days (curing of plastic resin systems or curing of concrete). A chemical reaction run in a laboratory beaker may be where things start, but in order to be commercially useful, materials must be produced on a larger scale, frequently in a continuous manner, using commercially available raw materials. These industrially used materials may have different quality and physical characteristics than their laboratory cousins. Since most chemical reactions either involve the generation of heat or require the input of heat, the practical means to do this must be chosen from many possible options, but for an industrial operation with the potential of release of hazardous materials, the backup utility system must be clearly defined. In addition, chemical reaction rates are typically logarithmic, not linear (e.g., as is the case with heat transfer), providing the possibility for runaway chemical reaction. Chemical engineers must design operations and equipment for such conditions.

Safety. There is no basic difference in the hazards or properties of a substance such as chlorine gas on any scale. Its odor, color, boiling point, and toxicity do not change from a small laboratory canister or cylinder to a 10 000 gallon tank car or bulk cylinders used in municipal drinking water disinfection. However, the release of such a material from large‐volume processes and tanks can have disastrous consequences to surrounding communities and the people living around them. Any large chemical complex has the same concern about the materials it uses, handles, and produces to ensure that its operations have minimal negative effects on the surrounding community and its customers. The incorporation of formal safety and reactive chemicals education within the college chemical engineering curriculum is a fairly recent and positive development. Chemical engineers are heavily involved not only in designing and communicating emergency plans for their operations but also in assisting the surrounding communities’ emergency response systems and procedures, including ensuring that the hazardous nature of materials used and processes are well understood.

Unit Operations. This is a unique chemical engineering term relating to the generic types of equipment and processes used in scaling up laboratory chemistry and the practice of chemical engineering. Heat transfer would be an example of such a unit operation. The need to cool, heat, condense, and vaporize materials is universal in chemical and material processing. The equations used to estimate the rate at which heat transfer occurs can be generalized into a simple equation such that Q (amount of energy transferred) is proportional to the temperature difference (ΔT) as well as the physical characteristics of the system in which the heat transfer is occurring (mixing, physical property differences such as density and viscosity). This would be expressed mathematically as Q = UAΔT. The amount of energy transferred and the temperature difference may be known, but the coefficient (frequently represented by the letter U) relating the two may vary considerably. However, this basic equation can be applied to any heat transfer situation. The same thoughts apply to many separation unit operations such as distillation, membrane transport, reverse osmosis membranes, chromatography, and other mass transfer unit operations. The rate of mass transfer is proportional to a concentration difference and an empirical constant, which will be affected by physical properties, diffusion rates, and agitation. In many chemical plant operations, there is an overlap in these areas. For example, a distillation column will involve both heat and mass transfer. The same is true for an industrial cooling tower. The last of these general topics is fluid flow. Though there are many types of pumps and compressors, they all operate on the same basic principle that says that the rate of flow is proportional to the pressure differential, the energy supplied, and the physical properties of the liquid or gas. Again, there is an overlap, as any equipment of this type is also using energy and heating up the liquid or gas it is moving. The heat transfer, as well as the fluid transfer, must be considered.

Process Design, Economics, and Optimization. There are numerous ways of scaling up a chemical production system. The choice of particular separation processes, transport systems, storage systems, heat transfer equipment, mixing vessels, and their agitation systems can be done in various combinations, which will impact reliability, cost, the way the process is controlled, and the uniformity of the output of the process. Design optimization is a term frequently used. The optimum design will not be the same for all companies making the same product as their raw materials base, customer requirements, energy costs, geographic location, cost of labor, and other company unique variables will affect the decision as to what is optimum. Our ability to computerize chemical engineering design calculations has greatly enabled chemical engineers’ capabilities to evaluate a large number of options.

Process Control. In a laboratory environment where small quantities of materials are made, the control system may be rather rudimentary (i.e., an agitated flask and on/off heating jacket). However, when this same reaction is scaled up orders of magnitude and possibly from batch to continuous, the nature of the process control changes dramatically. The continuous production of specification material around the clock has special challenges in that the raw materials (now coming from an industrial supplier and not a reagent chemical bottle) will not be uniform, the parameters of utilities needed to heat and cool will not be uniform, and the external environment will constantly change. Chemical engineers must design a control system that will not only have to react to such changes but also ensure that there are minimal effects on the product quality, the outside environment, and the safety of its employees.

As the field of chemical engineering has expanded, many curricula will also contain specialty courses in such areas as materials science, environmental chemistry, and biological sciences. However, even when these specialty applications are scaled to commercial size, the aforementioned basics will always be needed and considered.

What Do Chemical Engineers Do?

With this type of training, a unique combination of chemistry, mechanical engineering, and physics, chemical engineers find their skills used in a variety of ways. The following is certainly not an all‐inclusive list but represents a majority of careers and assignments of most chemical engineers:

The scale‐up of new and modified chemical processes to make new materials or lower cost/less environmentally impactful routes to existing materials. This is most often described as pilot plants, which typically is a middle step between laboratory chemistry and full‐scale production. In some cases this can involve multiple levels of scale‐up (10/1, 100/1, etc.) depending upon the risk factor and the knowledge that exists. A newly proposed process that has operating issues or causes safety releases in a laboratory environment is a serious issue. If that same problem occurs on a much larger scale, the consequences can be far more severe, simply due to the amount and scale of materials being inventoried and processed. These consequences can easily include severe injuries and death, large property damage, and exposure of the surrounding community to toxic materials.

Design of Processes and Process Equipment. It is rare that the equipment used in a full‐scale plant is identical in type to that used in the laboratory or possibly even in the pilot plant. The piping size; the number and type of trays in a distillation tower; the configuration of coils, tubes, and baffles in a heat exchanger; the shape and size of an agitator system; the shape and geometry of a solids hopper; the shape and configuration of a chemical reactor; and the depth of packing in a tower are all examples of such detailed design calculations. In the commercial world, there may be limitations of certain speeds, voltages, and piping specifications that may not match exactly with what may be desired from smaller‐scale work. In these cases, the chemical engineer, in collaboration with other engineers, needs to design a system that will achieve the desired goals, but within practical limitations. In many large chemical and petrochemical companies, chemical engineers will become experts in a certain type of process equipment design and focus most of their career in one particular area.

Though certainly not unique to the domain of chemical engineers, the design of utility support systems for chemical plant operations is critical. This includes the supply of water for process and emergency cooling, continuity of electrical supply for powered process equipment such as pumps and agitators, and supply of oil, gas, or coal to generate steam and power. Options chosen will certainly be affected not only by economics but also by limitations of a particular manufacturing site. These may include water availability, water and air permit limitations, and the reliability of local public utility supplies.

Sales and marketing positions in the chemical, petroleum, and materials industries are frequently filled by chemical engineers. The ability to understand the customer’s process may be critical to the ability to sell a material to a customer, especially if it is a new material or requires substantial change in a customer’s operation.

Safety and environmental positions, both within industry and government, are frequently filled by chemical engineers. In order to write rules and regulations, it is important to understand the basic limitations of chemical processes, laws of thermodynamics, and the limits of measurement capabilities. Regulations and enforcement actions relating to hazardous material transport also require chemical engineering expertise, especially in bulk pipeline, rail car, and truckload shipping.

Cost estimates in the chemical and petrochemical areas are also done by chemical engineers in conjunction with mechanical, civil, and instrumentation engineers. With the availability of today’s computer horsepower, it is possible to evaluate and compare many possible process options as a function of raw material pricing, geographic location, energy cost, and cost projections. This allows optimum process design and the ability to predict process costs and economics under changing conditions.

The supervision of actual chemical plant operations is most often done by chemical engineers. In this role, the understanding of equipment design and performance is critical, but more importantly the management of plant operations to minimize safety incidents and environmental releases, as well as complying with permits under which the plant is allowed to operate. In this role chemical engineers have additional unique responsibilities including labor relations with operating plant personnel as well as the need, in some cases, to interface with the surrounding community in a public communications role.

In universities and in advanced laboratories within many large corporations, basic chemical engineering research is done by advanced degreed chemical engineers, many times in association with other disciplines. Examples of such work would include chemical engineering principles used in the design of artificial organs (remember: the heart is a pump and the kidney is a filter), the study of atmospheric diffusion to study the impact of environmental emissions, the design and optimization of process control algorithms, alternative energy sources and processes, and the recovery of energy from waste products in an economical and environmentally acceptable way.

Many business and executive management positions, especially in chemical‐ and material‐based companies (both large and start‐up), are filled by chemical engineers. This may come from the advancement over time of newly hired engineers based on demonstrated capabilities (including technical, decision making, and people interaction and motivational skills), as well as the need to transfer chemical engineers with one area of management and technical expertise into another needing, but not having those skills.

The study of biological systems from a chemical engineering standpoint. This includes not only the previously mentioned human organs such as the heart (pumps) and kidneys (filters) but also absorption and conversion of food ingredients into the human body.

Development of System Models. As our basic understanding of chemical and engineering systems has advanced, it has become easier to mathematically model many process systems. This requires the combination of chemical engineering skills with knowledge of mathematical models and software that, in many cases, minimizes the cost of system scale‐up and evaluation.

Topics to Be Covered

The remainder of this book will be divided into chapters represented by the various chemical engineering unit operations, following an overview of safety, reactive chemicals, chemistry scale‐up, and economics. The following general introductory topics will be included as necessary as each major chemical engineering unit operation is reviewed:

Chapter 2: Safety and Health: The Role and Responsibilities in Chemical Engineering Practice. There is no perfectly safe chemical (people drown in room temperature water). What particular aspects of safety are important in chemical processing and engineering? What are some examples of materials available and used to evaluate hazards and plan for emergency situations? What kind of protective equipment may be required? What particular aspects of chemical safety require special planning and communication? What are some examples of public‐ and government‐required information? How do we decide on necessary protective equipment? In most cases of commercial processes, there is a wealth of safety and health information available, but discipline is required to review and keep up to date with the latest information. The stability of chemical systems to temperature and heat, oxygen, classes of chemicals, and external contamination must also be understood.

Chapter 3: The Concept of Balances. One of the core principles in chemical engineering is the concept of conservation principles. The amount of mass entering a process or a system, over some period of time, must be equal to what comes out. The same is true for energy with the addition or subtraction of energy change in any chemical reaction and also energy related to equipment operation such as pumps and agitators. Momentum, or fluid energy, is another property conserved in any process.

Chapter 4: Stoichiometry, Thermodynamics, Kinetics, Equilibrium, and Reaction Engineering. How a chemical reaction system, a separation system, a mixing system, a fluid transfer system, or a solids handling system is scaled up from their laboratory origins is one of the keys to a commercially successful chemical or materials operation. The methods for doing this are, in most cases, not linear extrapolations. If the scale‐up of a chemical process involves many different unit operations, whose scale‐up methods are different, this presents a unique challenge in the design of a large‐scale chemical process. Chemical reactions either require or generate heat. As will be discussed in more detail later, the rates of reactions and the ability to add and remove heat do not follow the same type of mathematical laws, requiring intelligent engineering design decisions to prevent accidents, injuries, and loss of equipment. Many chemicals will not react with each other under ambient conditions, but their potential products are desirable. Catalysts are materials with special surface properties, which, when activated in a particular way, allow chemicals to react at lower temperature or pressure conditions than otherwise required. They also may allow a higher degree of selectivity of products produced.

Chapter 5: Flow Sheets, Diagrams, and Materials of Construction. As a chemical process idea moves from a laboratory concept to full‐scale production, it typically moves through various stages. A mini‐plant, a small‐scale version of the lab process, might be run to test variables such as catalyst life, conversions and yields being steady over time, reproducibility of the product produced, and similar issues. A pilot plant might then be built, which might be a 100× scale of the lab process, but still 1/10th or 100th the size of the full‐scale plant. If it is necessary to provide product samples to a customer during this scale‐up process, a semi‐plant might be built. The prime function of such a unit is to supply product for customer evaluation, but it will certainly provide additional scale‐up and design information. A process being scaled up by a company that is already familiar with the general chemistry may skip one or more of these steps, considering the scale‐up risk to be minimal. As this scale‐up process moves along, flow sheets that describe how the process will operate and how its various process units will interact with each other become more detailed.

An industrial process rarely uses the same type of equipment used in the laboratory, and one of the key differences is in the materials used in the equipment that handles all the process materials. On a large scale, it is neither safe nor practical to use large‐scale glass equipment. Glass‐lined equipment is an alternative but can be expensive. Decisions on materials of construction are part of this process of scaling up a process. Decisions on materials to be used must be made and involves corrosion rates and products of corrosion, as well as balancing corrosion rates and product contamination with the possible added cost of corrosion‐resistant materials.

Chapter 6: Economics and Chemical Engineering. No chemical reaction or process is commercially implemented unless it provides a profit to someone. Many chemical reactions and formulations are proposed that never go beyond laboratory scale. There must be a demand for the material and the function it provides, and the value (price) of the product or service must be greater than the sum of the cost of its raw materials, the cost of the plant to produce the final product, the cost of any necessary and required environmental controls, the cost of final plant site cleanup and/or disposal, the cost of any borrowed funds invested, the cost of research and development related to the product and process, and the profitability demanded by a company and its shareholders. There may also be unique costs involved in the transportation and storage of any particular chemical.

As previously mentioned, the costs and quality of commercially available raw materials will differ significantly from laboratory reagents. In every case, if the quality will be lower, the raw materials will have impurities that are different, the levels of impurities may change with time, and costs of energy systems may vary. Since the construction of a commercial chemical operation may take many years to complete and the science of forecasting all of these variables is never perfect, estimates are made of changes in these inputs and how they would ultimately affect the cost of manufacture. Economics of making a material is also divided into components that are either fixed or variable, meaning that the costs vary directly with the production volume or they are relatively independent of the volume. The ratio of these two characteristics can have a dramatic impact on chemical or material process profitability as a function of volume and business conditions.

Chapter 7: Fluid Flow, Pumps, and Liquid Handling and Gas Handling. This chapter will review the basics of fluid flow including pumps, gas flow, piping systems, and the impact of changes in process conditions. Fluid transport equipment have limitations that must be understood prior to their choice and use. Fluid mixing can affect chemical reaction rates, uniformity of products produced, and energy costs used by various transport systems. Similar to mass and energy balances, fluid energy and momentum are also conserved in any fluid system, and these potential changes must be accounted for.

Chapter 8: Heat Transfer and Heat Exchangers. Since very few chemical reactions are energy neutral, heat must be either supplied or removed. There are many choices in heat transfer equipment as well as choices in how these various types of equipment are configured. Heat transfer systems are used to heat or cool the reaction systems, insulate piping to maintain a given temperature, maintain temperatures in storage systems, condense gases, boil liquids, and melt or freeze solids. The heating or cooling may also be used to control or change physical properties of a liquid or a gas. It may also be possible to use heat generated in one part of a process to utilize in another part of a process.

Chapter 9: Reactive Chemicals Concepts. This chapter, though separate due to its importance, combines aspects of kinetics, reaction engineering, and heat transfer in the analysis of what is commonly known as reactive chemicals. These aspects of engineering scale in the same way and, if not done correctly, can result in serious loss of life and equipment.

Chapter 10: Distillation. This is the most unique unit operation to chemical engineering. Many liquid mixtures, frequently produced from a chemical reaction, must be separated to recover and possibly purify one or more of the components. If there is vapor pressure or volatility difference between the components, the vaporization and condensation of this mixture done multiple times can produce pure products, both of the more volatile and less volatile components. This unit operation is at the heart of the oil and petrochemical industry that produces gasoline, jet fuel, heating oil, and feedstocks for polymer processes. Low temperature (cryogenic) distillation is also the basis for separating ambient air into its individual components of nitrogen, oxygen, and argon—all used in industrial and medical applications.

Chapter 11: Other Separation Processes: Absorption, Stripping, Adsorption, Chromatography, Membranes. Absorption is the unit operation that describes the removal or recovery of a component from a gas stream into a liquid stream. Stripping is the opposite, or the removal or recovery of a component from a liquid into a gas. Both of these unit operations have become more important over time as environmental regulations have decreased the amount of trace materials that can be discharged directly into the air or water. Adsorption is the use of gas/solid interaction to recover a component from a gas or liquid on to the surface of a solid, the fluid discharged, and the material on the solid surface later recovered via a change in pressure or temperature. The principles of adsorption can also be used to optimize the design of catalyst systems mentioned previously. Charcoal filters used to purify home drinking water are an example of this unit operation. Ion‐exchange resins are often used to soften water for home and industrial use.

Some mixtures require more advanced separation techniques. Water desalination is such an example. Due to basic thermodynamic properties, water would prefer to contain salt, if it is present, rather than to be in its pure state. It is necessary to overcome this natural state through the use of permeable selective membranes utilizing a pressure differential. This can be a less costly way of producing drinking water from salt water compared to evaporation. Separation of gases (i.e., air into nitrogen and oxygen) into their components can also be done via membrane‐based technologies versus cryogenic (below room temperature) distillation.

Chapter 12: Evaporation and Crystallization. Many chemical reactions result in a product dissolved in a process solvent. This can include salts dissolved in water systems. These types of solutions frequently require concentration to deliver a desired product specification or may require removal of a component whose solubility is lesser than the desire product. Heating or cooling such a solution can be used to evaporate or crystallize the solution and change its concentration of the dissolved solid. This unit operation and its principles overlap with heat transfer topic in Chapter 8.

Chapter 13: Liquid–Solids Separation. Filtration is basically the removal of solids from slurry for the purpose of recovering a solid (possibly produced via evaporation or crystallization). The purpose here could be either recovery of a valuable product, now precipitated, or further processing of a more pure liquid. A drip coffee maker is an example of filtration. This unit operation can be enhanced by the use of gravitational forces such as used in a centrifuge. A home washing machine in its spin cycle is an example of this unit operation.

Chapter 14: Drying. Many chemical products, in their final form, are solids as opposed to liquids or gases. The drying of solids (removal of water or a solvent from a filtration process) involves the contacting of the wet solid with heat in some form (direct contact, indirect contact) to remove the residual water or solvent. The degree of dryness needed is a critical factor in engineering design. The setting used in home clothes dryer is an everyday example.

Chapter 15: Solids Handling. The fundamentals of solids handling and storage are seldom included in chemical engineering curricula at the present time. However, the variables that determine how solids transport equipment (screw conveyors, pneumatic conveyors) operate are extremely important from a practical and industrial standpoint. The characteristics of solids and their ability to be transported and stored are far more complicated than liquids and gases and require the determination of additional physical properties to properly design such process units as bins and hoppers, screw conveyors, pneumatic conveyors, and cyclones. There are also some very unique safety concerns in solids handling, often ignored, that result in dust explosions. The caking of solids in a home kitchen storage unit is an everyday example of what can also happen in industrial processes and packaging.

Chapter 16: Tanks, Vessels, and Special Reaction Systems. Though the actual detailed design of structural supports, pressure vessels, and tanks is normally done by mechanical and civil engineers, the design requirements are often set by chemical engineers. Though tanks and vessels can be used to simply store materials for inventory or batch quality control reasons, they are also used as reactors. This can frequently involve mixing of liquids, gases, and solids; heat transfer; as well as pressure, phase, and volume changes.

Chapter 17: Chemical Engineering in Polymer Manufacture and Processing. These are materials produced from the reaction of monomers such as ethylene, styrene, propylene, and butadiene, which have reactive double bonds. When activated by thermal, chemical, or electromagnetic fields, these monomers can react among themselves to produce long chains of very high molecular weight polymers. Different monomers can be reacted together, producing co‐ and tri‐polymers with varying geometrical configurations. This class of materials has both unique processing and handling challenges due to unusual physical properties and the nonuniform distribution of chemical characteristics. They also have unique challenges in blending and compounding to produce final desired product properties such as color and melting characteristics.

Chapter 18: Process Control. All of the unit operations and their integration into a chemical process require the design of a control system that will produce the product desired by the customer. This chapter also covers the aspects of a control system necessary to deal with the safety and reactive chemical issues mentioned previously.

Chapter 19: Beer Brewing Revisited. In follow‐up to the first exercise, we will review the brewing of coffee from the standpoint of chemical engineering principles.

There are also appendices to provide additional discussion and reference materials.

Before we start our journey into the various aspects of chemical engineering, let us take a look at the flow sheet showing how beer is manufactured:

Figure 1.1 Beer manufacturing flow sheet.

Source: https://chem409.wikispaces.com/brewing+process. © Wikipedia.

Prior to reading the rest of this book, make a list of some of the chemical engineering issues that you see in designing, running, controlling, and optimizing the brewery process.

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We will revisit this process near the end of this book.

In addition we will use the brewing of coffee (starting at the very beginning) as an illustration of the principles we will present throughout the book.

Discussion Questions

1 What roles do chemical engineers fill in your operations and organization?

2 What unit operations are practiced in your process and facility? Which ones are well understood? Not well understood?

3 How are nonchemical engineers educated prior to their involvement in chemical process operations? Have there been any consequences due to lack of understanding of chemical engineering principles?

4 What chemical process operations are used in your process? How is the knowledge about these unit operations kept up to date? Who is responsible?

5 What areas in your organization’s future plans may involve chemical engineering?

Review Questions (Answers in Appendix with Explanations)

1 Chemical engineering is a blend of:

__Lab work and textbook study of chemicals

__Chemistry, math, and mechanical engineering

__Chemical reaction mechanisms and equipment reliability

__Computers and equipment to make industrial chemicals

2 Major differences between chemistry and chemical engineering include:

__Consequences of safety and quality mistakes

__Sophistication of process control

__Environmental control and documentation

__Dealing with impact of external variables

__All of the above

3 A practical issue in large‐scale chemical operations not normally seen in shorter‐term lab operations is:

__Personnel turnover

__Personnel protective equipment requirement

__Corrosion

__Size of offices for engineers versus chemists

4 Issues that complicate large‐scale daily chemical plant operations to a much greater degree than laboratory operations include all but which of the following:

__Weather conditions

__Emergency shutdown and loss of utility consequences

__Upstream and/or downstream process interactions

__Price of company, suppliers, and customer stocks that change minute by minute

5 A chemical engineering unit operation is one primarily concerned with:

__A chemical operation using single‐unit binary instructions

__Physical changes within a chemical process system

__Operations that perform at the same pace

__An operation that does one thing at a time

Additional Resources

Felder, R. M. and Rousseau, R. W. Elementary Principles of Chemical Processes, 3rd edition, John Wiley & Sons, Inc., 1, 2005.

Himmelblau, D. M. Basic Principles and Calculations in Chemical Engineering, Prentice Hall, 1967.

Peters, M. Elementary Chemical Engineering, McGraw Hill, 1984.

Solen, J. and Harb, J. Introduction to Chemical Engineering: Tools for Today and Tomorrow, 5th Edition, John Wiley & Sons, Inc., 2010.

http://www.aiche.org/academy (accessed August 29, 2016).