Experimental Methods and Instrumentation for Chemical Engineers

Gregory S. Patience

• Editore: Elsevier
• Anno: 2013
• ISBN:
  9780444538055
• Argomento: Physical Sciences
• Categoria: Chemistry

Experimental Methods and Instrumentation for Chemical Engineers is a practical guide for research engineers and students, process engineers and, consultants, and others in the chemical engineering field. This unique book thoroughly describes experimental measurements and instrumentation in the contexts of pressure, temperature, fluid metering, chromatography, and more. Chapters on physico-chemical analysis and analysis of solids and powders are included as well.

Throughout the book, the author examines all aspects of engineering practice and research. The principles of unit operations, transport phenomena, and plant design form the basis of this discipline. Experimental Methods and Instrumentation for Chemical Engineers integrates these concepts with statistics and uncertainty analysis to define factors that are absolutely necessary to measure and control, how precisely, and how often.

Experimental Methods and Instrumentation for Chemical Engineers is divided into several themes, including the measurement of pressure, temperature flow rate, physico-chemical properties, gas and liquid concentrations and solids properties. Throughout the book, the concept of uncertainty is discussed in context, and the last chapter is dedicated to designing and experimental plan. The theory around the measurement principles is illustrated with examples. These examples include notions related to plant design as well as cost and safety.

• Contains extensive diagrams, photos, and other illustrations as well as manufacturers' equipment and descriptions with up-to-date, detailed drawings and photos
• Includes exercises at the end of each chapter, helping the reader to understand the problem by solving practical examples
• Covers research and plant application, including emerging technologies little discussed in other sources

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.

Throughout the day, we make measurements and employ instrumentation. The clothes that we wear, the food that we eat, the objects that we manipulate have all been developed and optimized through the use of standardized procedures and advanced instrumentation. The transportation sector is an example where instrumentation and sensors are commonplace: gauges in the car assess speed, engine temperature, oil level, fuel level, and even whether or not the seat belt is engaged. One of the key factors in homes is maintaining the correct temperature either in rooms, refrigerators, hot water heaters, ovens, or elements on the stove. Advanced scales now display not only body weight but also percent fat and percent water!

Development is the recognition and application of unrelated or non-obvious phenomena to a new or improved application—like making fire. Optimization of innovations and technology can be achieved through accidents, trial-and-error testing, or systematic approaches. Observation is the fundamental basis for measuring devices and it was the main technique employed by man to understand the environment in which we lived as interpreted by our senses: sight, sound, smell, touch, hearing, time, nociception, equilibrioception, thermoception, etc.

The manufacture of primitive stone tools and fire required a qualitative appreciation for the most common measures of mass, time, number, and length. The concept of time has been appreciated for millennia. In comparative terms it is qualified by longer and shorter, sooner and later, more or less. Quantitatively, it has been measured in seconds, hours, days, lunar months, and years. Calendars have existed for well over 6000 yr and clocks—instruments to measure time intervals of less than a day—were common as long as 6000 yr ago. Chronometers are devices that have higher accuracy and laboratory models have a precision of 0.01 s.

One of the first 24-h clocks was invented by the Egyptians with 10 h during the day, 12 h at night, and 1 h at dawn and dusk—the shadow hours. The night time was measured by the position of the stars in the sky. Sun dials were used at the same time by Babylonians, Chinese, Greeks, and Romans. The water clock (clepsydra) was developed by Egyptians to replace the stars as a means of telling time during the night: Prince Amenemhet filled a graduated vessel with water and pierced a hole in the bottom to allow the water to drain (Barnett, 1998). Records of the hourglass date back to the early 13th century but other means to “accurately” measure time included burning candles and incense sticks.

Recording time required a numbering system and a means of detecting a change in quantity. In the simplest form of a water clock, time was read based on the liquid level in the vessels as indicated by a notch on the side. The system of using notches on bones, wood, stone, and ivory as a means of record-keeping dates before the Upper Paleolithic (30 000 BC). Notch marks on elongated objects are referred to as tally sticks. Medieval Europe relied on this system to record trades, exchanges, and even debt, but it was mainly used for the illiterate. It was accepted in courts as legal proof of a transaction. Western civilization continues to use tally marks as a means of updating intermediate results. This unary numeral system is written as a group of five lines: the first four run vertically and the fifth runs horizontally through the four.

Perhaps one of the driving forces throughout the ancient civilizations for numbering systems was for taxation, lending, land surveying, and irrigation. The earliest written records of metrology come from Sumerian clay tablets dated 3000 BC. Multiplication tables, division problems, and geometry were subjects of these tablets. The first abacus—an ancient calculator used to perform simple arithmetic functions—appeared around 2700–2300 BC. Later tablets—1800–1600 BC—included algebra, reciprocal pairs, and quadratic equations. The basis for 60 s in a minute, 60 min in an hour, and

in a circle comes from the sexagesimal numeral system of the Sumerians (Mastin, 2010). Moreover, unlike the Greeks, Romans, and Egyptians, they also had a decimal system. The Pythagorean doctrine was that mathematics ruled the universe and their...