Air Pollution Control Engineering for Environmental Engineers

Fundamentals and Applications

Jeff Kuo, Jeff Kuo

• Editore: CRC Press
• Anno: 2018
• ISBN:
  9780429524448
• Edizione: 1
• Argomento: Business
• Categoria: Infrastrutture

Air pollution control and air quality engineering are some of the key subjects in any environmental engineering curriculum. This book will cover topics that are fundamental to pollution control engineers and professionals, including air pollution and its management through regulatory approaches, calculating and estimating emissions, and appying con

Chapter 6

Control of Particulate Emissions

Particulate matter (PM) is one of the six criteria pollutants. Reducing particulate emissions from stationary source is vital to achieve good ambient air quality. There are many types of control devices available, and removal mechanisms of these devices vary. Characteristics of particulates and of the gas stream will have significant impacts on their removal.

This chapter starts with an introduction on sources of particulate emissions, particulate removal and types of commonly-used removal devices, and characteristics of gas stream and particulate that are relevant to particulate removal (Section 6.1). Section 6.2 describes particle size, particle size distribution, particulate Reynolds numbers and detailed discussion on particulate removal mechanisms. Principles, commonly-used systems and their components, important design considerations, and design calculations related to gravity settling chambers are presented in Section 6.3. Those of cyclones, electronic precipitators, fabric filters, and wet scrubbers are presented in Sections 6.4, 6.5, 6.6, and 6.7, respectively. Section 6.8 summarizes important considerations in selection of proper particulate removal devices.

6.1 Introduction

Particulate matter (PM) is a general term that describes solid particles and liquid droplets present in the atmosphere and gas streams. An obvious effect of PM pollution is reduction of visibility. Emission from a stack or a tail pipe is visible mainly because of the PM it carries. Elevated PM concentrations in the ambient air also pose threats to human health, ecosystem, and the environment.

6.1.1 Sources of particulate emissions

Particles are being emitted to the atmosphere from natural processes and human activities. Some particles are formed in the atmosphere. Solid particles can be generated from mechanical action (e.g., grinding), chemical reactions (e.g., metal oxides), and incomplete combustion (e.g., carbon black). Liquid particles can be generated from chemical reactions and condensation.

Primary particles are those released directly from sources to the atmosphere. They include wind dusts, ocean sprays, volcano ash, and carbon black from combustion sources. Secondary particles are those formed in the atmosphere from chemical reactions involving primary gaseous pollutants. Examples of secondary particles are ammonium sulfate ((NH₄)₂SO₄) and ammonium nitrate (NH₄NO₃), formed from gaseous emissions from various combustion sources. When compared to primary particles, they are much smaller in size and represent a large portion of PM₂₅ in our ambient air.

Tables 6.1 and 6.2 tabulate the PM₁₀ and PM₂₅ emissions from main sources categories in the U.S. in 2017. The total emissions are 18.1 and 5.3 million tons for PM₁₀ and PM_2.5, respectively. Contributions to PM₁₀ emissions are 86.6, 4.8, 6.1, and 2.5% from miscellaneous, stationary fuel combustion, industrial and other processes, and transportation, respectively. Contributions to PM_2.5 emissions are 69.3, 14.0, 11.3, and 5.4% from miscellaneous, stationary fuel combustion, industrial and other processes, and transportation, respectively. Miscellaneous source category (e.g., w...