Air Pollution Control Equipment Selection Guide, 2nd Edition

xiii

Preface

It is gratifying as an author to nd that the product of my effort is being put to good

use. In my travels, I’ve seen copies of the rst edition of the Air Pollution Control

Equipment Selection Guide in a wide variety of libraries and on numerous book-

shelves. Some are in the corporate libraries of consulting rms, some at colleges and

universities, and others in private collections. Some of these copies have dog-eared

pages indicating that the reader must have found something of interest and may want

to return. That is why the rst edition book was produced. It was intended to be a

valuable reference resource over time.

For the second edition, the operative word is listening. Readers liked the gen-

eral format of the rst edition and that format is retained herein. The Device Type,

Typical Applications and Uses, Operating Principles, Primary Mechanism Used,

Design Basics, and Operating Suggestions format for each chapter remains. The use

of this format for each chapter allows the reader to compare within those categories.

If you are familiar with the technology, for example, but want to explore various

applications, you can easily do so. If you are interested in the basics of the design

of a particular piece of equipment, you can go to those sections. The tone remains

conversational rather than scientic.

When asked what additional information they would like to see, readers of the

rst edition mentioned a number of things, which, I hope, have been addressed in

this second edition. For example, they asked for an expansion of the “Air Pollution

Control 101” chapter (maybe it should now be “Air Pollution Control 102”?) to

include comments about dealing with gases that are far aeld from ambient air.

These conditions occur quite often today regarding gasication systems wherein the

gas stream may contain lower molecular weight gases under much higher pressures

than ambient conditions.

For the chapter on cyclone collectors, additional information is provided regard-

ing large diameter, product recovery type cyclones that are used on rotary dryers

and the like.

Where appropriate, additional up-to-date information is provided under the

Typical Applications and Uses sections. For example, the “Fabric Filter Collectors”

chapter was enlarged and rened to include spray dryer fabric lter collector com-

bination systems for acid gas and mercury control. Photos of some existing installa-

tions are provided.

A group of chapters (21–23) is now included featuring Special Applications. The

hybrid type systems noted here may combine various wet or dry scrubbing tech-

niques or form a team of various technologies to solve a specic problem wherein

one technology alone would be insufcient. For other challenges, the use of a spe-

cic technique is modied. As an example, sometimes Venturi scrubbers are used as

evaporators rather than particulate control devices. Their proper design, however, is

required to minimize any particulate generation resulting in air pollution. A special

chapter on Venturi evaporators has therefore been added. Coupled with a packed or

xiv Preface

tray tower device, that Venturi evaporator “hybrid” can also recover the evaporated

water, or recover heat, or both.

It seems that some owners of the rst edition already have air pollution control

equipment and want to improve its performance. Initially, they used the book to

explore alternative technologies to replace the problem device, but given the cost

of replacement, their focus shifted to how to get the most out of their existing

hardware. So, in response, a special chapter was added to address that request.

That new chapter, “System Diagnostics and Testing” (Chapter 24), goes over basic

problem diagnosis for both wet- and dry-type gas cleaning equipment and provides

some remedial suggestions. Therefore, the reader may want to use the second edi-

tion as a resource to select new hardware or to modify and keep what they have. If

you are thinking of salvaging your existing gas cleaning system, you may want to

read the last chapter rst!

Much of the information contained herein derives from the past nearly ve

decades in the air pollution control industry. The industry is dynamic and challeng-

ing. To provide improved content, I turned to the most reliable source, colleagues

and friends met during those decades. I am profoundly grateful for the information,

pictures, and other content supplied by these contributors and hope that the reader is

pleased with the result.