An Applied Guide to Process and Plant Design

Sean Moran

• Publisher: Butterworth-Heinemann
• Year: 2015
• ISBN:
  9780128003824
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

An Applied Guide to Process and Plant Design is a guide to process plant design for both students and professional engineers.The book covers plant layout and the use of spreadsheet programmes and key drawings produced by professional engineers as aids to design; subjects which are usually learned on the job rather than in education. You will learn how to produce smarter plant design through the use of computer tools, including Excel and AutoCAD, "What If Analysis", statistical tools, and Visual Basic for more complex problems. The book also includes a wealth of selection tables, covering the key aspects of professional plant design which engineering students and early-career engineers tend to find most challenging.Professor Moran draws on over 20 years' experience in process design to create an essential foundational book ideal for those who are new to process design, compliant with both professional practice and the IChemE degree accreditation guidelines.

• Explains how to deliver a process design that meets both business and safety criteria
• Covers plant layout and the use of spreadsheet programmes and key drawings as aids to design
• Includes a comprehensive set of selection tables, covering those aspects of professional plant design which early-career designers find most challenging

Part 1

Practical Principles

Outline

Introduction

Chapter 1 Process Plant Design

Chapter 2 Stages of Process Plant Design

Chapter 3 Process Plant Design Deliverables

Chapter 4 Twenty-First Century Process Plant Design Tools

Chapter 5 The Future of Process Plant Design

Introduction

Seán Moran

Process plant design is the pinnacle of chemical engineering design. Chemical engineering was developed based on the insight by Davis that all process industries used similar unit operations, which could be understood using sector independent analytical tools. Many “design tools” now commonly taught in academia incorporate assumptions that imply that all chemical engineering design is for the petrochemical sector, but chemical engineering has encompassed food and drink, inorganic chemical manufacture, and so on since its inception.

This book is about Process Plant design and, while examples may be drawn from my personal experience in the water and environmental sectors, it is intended to reflect consensus practice across the broad discipline. The IChemE’s “Chemical Engineering Matters” discussion document identifies the energy, water, food and nutrition, health, and well-being sectors as the future of Chemical Engineering. We need to avoid confusion between chemical engineering and petrochemical engineering, a small and arguably diminishing subset of the discipline.

I have spoken and corresponded with hundreds of process engineers, most notably in the United Kingdom, Middle and Far East, in all industries to verify that the approaches suggested in this book do represent current consensus practice. It seems that professional practice has not changed very much over the last couple of decades, but that what is taught in universities has drifted further and further from professional practice during that period.

I am writing this book because I think that Chemical Engineering Education has lost its way, and become too theoretical and abstract to adequately serve its purpose, namely to provide the “academic formation of a Chartered Chemical Engineer” as the UK’s IChemE puts it in its course accreditation guidelines.

The book is based on material I have delivered as part of the design courses I teach at the University of Nottingham, which is in turn based in my continuing professional engineering practice and professional training of my fellow engineers. It should be of use to undergraduate and postgraduate students, as well as early-career process plant designers and to university lecturers who wish to teach a more realistic version of plant design.

The book is in five parts. Firstly, I explain what process plant design is and how it is done in broad terms, then I give advice on professional practice in the most important aspects of process plant design, in general, and then at low and at high levels, and lastly I cover more advanced aspects of design.

It should be noted that this is a book about process plant design, rather than what is known nowadays in research-led universities as process design. There is no such thing as process design—processes happen in plants, and plants are the things which engineers design.

It has become clear in writing this book that we as a profession unhelpfully use the same words to mean different things. The meaning of the words and phrases Conceptual Design; HAZOP; Functional Design Specification; Design Philosophy; Design Basis; Process Intensification; Process Design; Optimization; Reproducibility; Repeatability; and Precision were particularly contested.

I have explained the sense in which I have used these words in the text at the point of first using them, and have included a glossary at the end. I am not claiming that my usage is the only correct one, but I have used them consistently in the book, and reflect to the best of my knowledge the most common meaning.

2014

Chapter 1

Process Plant Design

Process plant design involves making choices between a great many options in an uncertain environment in order to optimize cost, safety, and robustness. Professional design processes are similar across disciplines, sectors, and worldwide, as a result of their evolution to fit the professional design environment. Academics have dreamt up many alternatives to them, but these captive-bred strains never survive in the wild.

Keywords

Process plant design; engineering; methodology

Introduction

Whilst this may not be as obvious to today’s students of the subject as it should be, chemical engineering is a kind of engineering, rather than a branch of chemistry.

Similarly, professional engineering design practice has next to nothing to do with the thing called process design in many university chemical engineering departments.

I will cover the reasons for this elsewhere, but first let’s start by dispelling some confusion, by clearing up what engineering is (and is not), and what design is all about.

What is engineering?

I still feel glad to emphasize the duty, the defining characteristic of the pure scientist—probably to be found working in universities—who commit themselves absolutely to specialized goals, to seek the purest manifestation of any possible phenomenon that they are investigating, to create laboratories that are far more controlled than you would ever find in industry, and to ignore any constraints imposed by, as it were, realism.

Further down the scale, people who understand and want to exploit results of basic science have to do a great deal more work to adapt and select the results, and combine the results from different sources, to produce something that is applicable, useful, and profitable on an acceptable time scale.

C.A.R. Hoare

Engineers are those people “further down the scale” as Hoare the classicist and philosopher puts it, although I disagree that we “exploit the results of basic science.” Our profession stands on other foundations, though you may have been taught something different in university.

In academia there is almost universal confusion between mathematics, applied mathematics, science, applied science, engineering science, and engineering. Allow me to unconfuse anyone so confused before we get started:

Mathematics is a branch of philosophy. It is a human construction, with no empirical foundation. It is made of ideas, and has nothing to do with reality. It is only “true” within its own conventions. There is no such thing in nature as a true circle, and even arithmetic (despite its great utility) is not factually based.

Applied mathematics uses mathematical tools to address some real problem. This is the way engineers use mathematics, but many engineers use English too. Engineering is no more applied mathematics than it is applied English.

Science is the activity of trying to understand natural phenomena. The activity is rather less doctrinaire and rigid than philosophers of science would have us believe, and may well not follow what they call the scientific method, but it is about explaining and perhaps predicting natural phenomena.

Applied science is the application of scientific principles to natural phenomena to solve some real-world problem. Engineers might do this (though mostly they do not) but that doesn’t make it engineering.

Engineering science is the application of scientific principles to the study of engineering artifacts. The classic example of this is thermodynamics, invented to explain the steam engine, which was developed without supporting science.

Science owes more to the steam engine than the steam engine owes to Science.

L.J. Henderson

This is the kind of science which engineers tend to apply. It is the product of the application of science to the things engineers work with, artificial constructions rather than nature.

Engineering is a completely different kind of thing from all preceding categories. It is the profession of imagining and bringing into being a completely new artifact which achieves a specified aim safely, cost-effectively, and robustly.

It may make use of mathematics and science, but so does medicine if we substitute the congruent “medical science” for “engineering science.” If engineering was simply the application of these subjects, we could have a more-or-less common first and second year to medical and engineering courses, never mind the various engineering disciplines.

Now that we are clear about what engineering is, let us consider what design is.

What is design?

Rather than being some exotic province of polo-necked professionals, the ability to design is a natural human ability. Designers imagine an improvement on reality as it is, we think of a number of ways we might achieve the improvement, we select one of them, and we transmit our intention to those who are to realize our plan. The documents with which we transmit our intentions are, however, just a means to the ultimate end of design—the improvement on reality itself.

I will discuss in this book a rather specialized version of this ability, but we should not lose sight of the fact that design is in essence the same process, whether we are designing a process plant, a vacuum cleaner, or a wedding cake.

Designers take a real-world problem on which someone is willing to expend resources to resolve. They imagine solutions to that problem, choose one of those solutions based on some set of criteria, and provide a description of the solution to the craftsmen who will realize it. If they miss this last stage and if the design is not realized, they will never know whether it would have worked as they had hoped.

All designers need to consider the resource implications of their choices, the likelihood that their solution will be fit for the purpose for which it is intended, and whether it will be safe even if it not used exactly as intended.

If engineers bring a little more rigor to their decision making than cake designers, it is because an engineer’s design choices can have life and death implications, and almost always involve very large financial commitments.

So how does engineering design differ from other kinds of design?

Engineering design

Engineering probl...