Experimental Methods and Instrumentation for Chemical Engineers Experimental Methods and Instrumentation for Chemical Engineers

Experimental Methods and Instrumentation for Chemical Engineers Experimental Methods and Instrumentation for Chemical Engineers Gregory S. Patience AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Elsevier 225 Wyman Street, Waltham, MA 02451, USA The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK Radarweg 29, PO Box 211, 1000 AE Amsterdam, The Netherlands First edition 2013 Copyright © 2013 Elsevier B.V. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. 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Preface Throughout the day, we constantly make use of experimental methods, whether or not we are aware of it: we estimate physical properties like time, distance, and weight, as well as probability and expectation. For example, what is the probability that I will be late if I sleep another five minutes? (What is the probability that I will only sleep an additional five minutes?) Many of us look at the weather forecast to gauge what clothes to wear. Following a recipe to bake or prepare a meal is an example of an experimental procedure that includes the classic engineering quantities of temperature, time, mass (volume) and length. The principles of chemistry and chemical engineering were perhaps first formulated in the kitchen. The undergraduate course on Experimental Methods offered in my department was, in the beginning, primarily based on the textbook written by J.P. Holman entitled “Experimental Methods for Engineers.” This is an excellent textbook and is particularly suited for mechanical (and perhaps electrical) engineers, but elements particular to Chemical Engineering are lacking. For this reason, we embarked on the daunting task of compiling a version suited to the needs of Chemical Engineers. The chapters often begin with a historical perspective to recognize the work of early pioneers but also to stimulate the imagination of the students. For example, 10 000 years ago, man created plaster from limestone. Plaster requires temperatures nearing 900 ºC, which is well over 100 ºC hotter than an open pit fire. This technology required considerable resources: 1 t of wood (chopped by stone axes), 500 kg of limestone, a pit 2 m in diameter and 0.7 m deep, rocks to insulate, and two days to burn. Modern manufacturing errors are costly and a nuisance; in prehistoric times, errors would have been considerably more than just an inconvenience. In Chapter 1, the rules of nomenclature are reviewed—units of physical quantities, abbreviations, conversion between SI and British Units—and the various national and international standards bureaus are mentioned. Chapter 2 introduces significant figures and concepts of accuracy, precision and error analysis. Experimental planning is discussed in some detail in Chapter 3. This subject is enormous and we try to distil the essential elements to be able to use the techniques. Chapters 4 and 5 cover many aspects of measuring pressure and temperature. The industrial context is often cited to provide the student with a picture of the importance of these measurements and some of the issues with making adequate measurements. Flow measurement instrumentation is the subject of Chapter 6. A detailed list of the pros and cons of most commercial xi xii Preface flow meters is listed. Example calculations are detailed throughout the book to help the students grasp the mechanics of solving problems but also to underline pitfalls in making these calculations. Chapter 7 deals with the three major physicochemical properties in Chemical Engineering, including thermal conductivity, viscosity, and diffusion. Measuring gas and liquid concentration is the subject of Chapter 8—many analytical instruments are mentioned but chromatography is primarily described. Finally, in Chapter 9 we discuss powder and solids analysis— physical characterization as well as practical examples in Chemical Engineering. This manuscript has been a collaborative effort from the beginning. I would particularly wish to recognize the contributions of Melina Hamdine who early on in the project drafted several chapters in French including Physicochemical Properties, Analysis of Powders and Solids, and Design of Experiments. Much of the material on DOE was based on the contribution of Prof. Bala Srinivasan. Katia Senećal was “instrumental” in gathering the essential elements for the chapters including Measurement Analysis, Pressure, Temperature and Flow Rate. Prof. Bruno Detuncq collaborated in the revision of these chapters. Danielle Be´land led the redaction of the chapter on chromatography to deter- mine concentration with some assistance from Cristian Neagoe. He also wrote the section concerning spectroscopy. Amina Benamer contributed extensively to this project, including preparing solutions to the problems after each chapter, writing sections related to refractometry and X-ray and translating. Second-year students from the Department also participated by proposing original problems that were added at the end of each chapter (together with the name of the author of the problem). Ariane Be´rard wa devout at identifying errors and proposing additional problems. I would particularly like to recognize Paul Patience for his tremendous contribution throughout the creative process of preparing this manuscript. The depth of his reflection has been appreciated tremendously (LATEX). He also co-authored the section on pyrometry. Christian Patience prepared many of the drawings and Nicolas Patience helped with translating from French to English, as did Nadine Aboussouan. Chapter 1 Introduction 1.1 OVERVIEW Experimental methods and instrumentation—for the purpose of systematic, quantifiable measurements—have been a driving force for human development and civilization. Anthropologists recognize tool making, together with language and complex social organizations, as a prime distinguishing feature of Homo sapiens from other primates and animals. However, the animal kingdom shares many concepts characteristic of experimentation and instrumentation. Most animals make measurements: cheetahs, for example, gauge distance between themselves and their prey before giving chase. Many species are known to use tools: large arboreal primates use branches as levers for displacement from one tree to another; chimpanzees modify sticks as implements to extract grubs from logs; spiders build webs from silk to trap their prey; beavers cut down trees and use mud and stones to build dams and lodges. Adapting objects for a defined task is common between man and other animals. If the act of modifying a twig to extract grubs is considered “tool making” then a more precise differentiating factor is required. Man uses tools to make tools and a methodology is adapted to improve an outcome or function. One of the earliest examples of applying methodology is in the manufacture of chopping and core tools— axes and fist hatchets—that have been used since before the Lower Paleolithic period (from 650 000 to 170 000 BC): blades and implements were produced through cleaving rocks with a certain force at a specific angle to produce sharp edges. The raw material—a rock—is modified through the use of an implement—a different rock—to produce an object with an unrelated function (cutting, scraping, digging, piercing, etc.). Striking rocks (flint) together led to sparks and presumably to the discovery of how to make fire. Experimental Methods and Instrumentation for Chemical

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