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Introduction to Pollution Control
Has a regulatory agency announced regulations in your industry or declared your workplace unhealthy? Do your neighbors complain about odors? Do you face the dilemma of balancing company profitability with the demand to meet environmental requirements? This quick guide will explain all the basics of pollution control. It will help you understand the technologies and prepare you to make informed, knowledgeable decisions. All defined terms will be highlighted in blue and can be found in the Definitions section. The first concept to recognize is that many distinctly different industries have similar pollution problems and solutions. Once you understand the basics, then we can help you begin to decide which is the best for you. Always contact an Anguil representative to discuss particular applications and solutions. For now, all that you need to know is that hazardous air pollutants (HAPs) and Volatile Organic Compounds (VOCs) are, in fact, harmful to you and the environment. There are hundreds of science journals and EPA documents that can explain why toluene, ethanol, and other organic compounds are bad for your health, but for our purposes, we just need to know that they are. The lessons are broken down into manageable sections. You can jump ahead at any point, but each section is fairly brief.
What are VOCs? First of all, let's define the organic compound part of Volatile Organic Compounds (VOCs). Organic compounds are compounds that contain carbon and hydrogen. They occur naturally and can be found in all living things, but the majority of the organic compounds that we use are man-made. Some organic compounds are liquids that require an additional process like heating or cooling to create vapor. These organics are stable compounds. Other organic compounds are unstable; an organic compound is considered volatile if it produces a vapor (a gas) at room temperature and normal atmospheric pressure. (Think of the fumes you see on gas pumps without vapor recovery nozzles.) Some of these vapors are dangerous to humans when inhaled in great quantities or over a long period of time. Some volatile organic compounds interrupt and destroy natural plant processes. But many of the volatile compounds have a much more complicated effect: they lead to the formation of ozone and smog. Ozone is three oxygen atoms bonded together to form O3. Ozone occurs naturally, but the introduction of large amounts of VOCs into our lower atmosphere (the air closest to us) has caused an unhealthy amount of ozone to be created. Oxygen + VOCs + Sunlight + Combination of complex reactions leads to the formation of ozone. In the earth's upper atmosphere, ozone is an important layer that protects the earth from the sun's ultraviolet rays. But closer to the earth, ozone is a dangerous compound. It mixes with other compounds in the air and becomes the main component of smog. Smog is more than an ugly brown cloud hovering over the cities of the world. Smog causes respiratory ailments and heart conditions; it destroys agriculture and forests. In short, smog damages our entire environment. The best way to prevent the increase in ozone and smog is to eliminate these harmful VOCs from being released. Anguil's oxidation technology is designed to do just that. What are HAPs? A Hazardous Air Pollutant (HAP) is a Volatile Organic Compound that has additional harmful properties. The effects of HAPs are even more severe than VOCs. According to the U.S. Environmental Protection Agency, HAPs cause 1,000 to 3,000 cancer deaths a year in the U.S. They can cause birth defects, nervous system damage and, during massive accidental releases, death. HAPs also cause serious environmental damage. Fortunately, pollution control technologies can capture and destroy HAPs before they are released into the atmosphere. Again, the most effective destruction of HAPs and VOCs is accomplished by oxidation. What is oxidation? At the heart of most pollution control technologies is a concept we all learned in our early chemistry classes. That concept is oxidation; it causes compounds (in this case, contaminated air pollutants) to be broken up and reformed into new (in this case, safe) compounds. Add the right amount of heat and oxygen to hydrocarbons and you create oxidation. (To be scientific, the process is: Cn H2m + (n + m/2) O2 Þ n CO2 + H2O + Heat ) In the thermal oxidation process, the contaminated air is heated, breaking apart the contaminated compounds. The compounds will reform naturally, bonding into the harmless compounds of carbon dioxide and water vapor and releasing energy. During catalytic oxidation, however, the contaminated compounds in the air react with a catalyst material (platinum, palladium, rhodium, etc.) which breaks apart the contaminated bonds more easily. This premise is basic to all oxidation technologies: breaking the harmful compounds into harmless compounds and energy. Thermal oxidation requires high temperatures to break apart the compounds. The large amounts of fuel needed to maintain high temperatures can be expensive. Different pollution control technologies help reduce the long-term costs of the equipment. Catalysts, for example, react and oxidize the VOCs at a lower temperature, meaning less fuel and lower costs. No matter which oxidation technology is best suited for your application, the "three T's" of oxidation always apply: Temperature, Time and Turbulence.
A successful technology achieves full oxidation of VOCs by maintaining the proper mixture of oxygen and contaminants at the required temperature for a sufficient amount of time. Recuperative heat exchangers can also be added to thermal and catalytic oxidizers to recover between 50% and 75% of the heat released during oxidation. Another system advance is the Regenerative oxidizer, which uses multiple ceramic chambers to recover as much as 90% to 95% of the heat from oxidation. The Rotor Concentrator is another unique approach to reducing long-term costs. By absorbing and then concentrating the VOC into a smaller airflow, the Rotor Concentrator allows for the smallest oxidizer possible. The secret is to determine which technology works best and most cost effectively in each application. How do I decide which technology to use? Don't be too overwhelmed. This may all be new to you, but Anguil has over 1,600 successful installations in a wide variety of industries to provide us with the experience and knowledge to solve your problem. Here are the basics. In general, your decision is based on airflow and the amount and type of VOCs you are emitting. After the rate and content of your airflow are analyzed, the proper technology selection can be made.  This chart will help you begin to understand the process; the %LEL is the Lower Explosive Limit of your VOCs and the SCFM is the flow rate of your process after being adjusted to standard temperature and pressure. You may know your emission flow rate; your %LEL is based on the type and concentration of your contaminant. This chart is just the beginning, so don't worry if you aren't sure where your process lies on the chart -you probably don't. As we mentioned at the start, you don't need to know everything. We just want you to feel comfortable as we walk through your application with you and determine the optimum solution. Basic Definitions
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