What are hydrocarbons?
A hydrocarbon is an organic compound consisting of only hydrogen and carbon atoms. They are group 14 hybrids, which means they contain hydrogen, as well as atoms of the carbon 14 group; carbon, silicon, germanium, tin, and lead. Carbon has 4 electrons, which means it has exactly 4 bonds to make, to be stable. Another type of hydrocarbons are aromatic hydrocarbons, which include alkanes, cycloalkanes, and alkyne-based compounds. Hydrocarbons can form more complex compounds, like cyclohexane, by bonding to themselves. This is known as catenation.
Where are hydrocarbons found?
Almost all hydrocarbons occur naturally in crude oils, like petroleum and natural gas. Since crude oil is made of decomposed organic matter, it is abundant in hydrogen and carbon atoms. They are also present in different trees and plants, and form a natural pigment called carotene, that can be found in carrots and green leaves. The majority of natural crude rubber, 98%, is made of a hydrocarbon polymer; this is formed when a chainlike, molecule forms, consisting of many units linked together.
What are hydrocarbons used for?
Hydrocarbons are the most widely used organic compound on the planet, and the main component of VOCs. They are considered the driving force for modern civilization, because the makeup fossil fuels. These fuels are used for combustion, specifically in heating and motor fuel applications. Hydrocarbons like propane and butane are used in lanterns, lighters, grills, and as fuel for internal combustion units. Pentane, another common hydrocarbon. When saturate, pentane becomes a room temperature liquid; this liquid is used as an organic solvent, transport fuels, and cleansers. Liquid hydrocarbons are rated in combustion properties, relative to octane; ie; gasoline for internal combustion in engines in cars, trucks, and lawnmowers. Slightly larger hydrocarbon molecules, known as kerosene, jet fuel, diesel fuel, and oil for heating. The larger the hydrocarbons, the thicker the compound. Large hydrocarbons are often used as engine lubricants, and greases. Anything thicker than that, and they form a wax or tar like substance, which is commonly used in highway construction, and roofing.
Most of the hydrocarbons listed above are the result of thermal cracking, and fractional distillation of crude oils. But another very common source is the industrial processing of ethanol, to produce ethylene. The ethylene produced is used for the industrial synthesis of other hydrocarbons.
Why are hydrocarbons a concern?
On their own, hydrocarbons pose no risk. However, when exposed to sunlight and/or nitrogen oxides, they undergo a chemical reaction. It is well known that emissions and pollution created by human beings in this industrial age are dangerous, and hydrocarbons make up a large portion of these damaging compounds. Hydrocarbons are the main component of crude oil, natural gases, and most pesticides. All of these substances contribute to the greenhouse effect, and the depletion of the ozone layer. They also reduce the photosynthetic ability of plants, increase cancer rates in humans and animals, and increase the risk of respiratory illness. The most well-known and document dangerous of hydrocarbons is oil spills. Oil spills destroy marine plant life, and kill and endanger hundreds of thousands, if not millions, of animals each year.
How do we treat hydrocarbons?
Since hydrocarbons are one of the most common compounds used in industrial processes and fuel burning, there are several ways to destroy or abate them.
The first would be through biofiltration. Biofiltration is the process of utilizing natural biological oxidation for the destruction and removal of VOCs, odors and hydrocarbons. Simply put, biofiltration is the degradation of organic and inorganic substances by microorganisms. The air flows through what is called a packed bed of media causing the pollutants to transfer into a thin biofilm on the surface of the packed media. The microorganisms are housed in the microfilm and degrade the pollutants. The most common uses of biofiltration, bioscrubbers and biooxidizers include in the processing of waste water, capture of VOCs in surface runoff and microbiotic oxidization of air contaminants.
Another way to treat hydrocarbons would be with a Vapor Combustion Unit or Flare. A Vapor Combustor Unit (VCU), or flare, is an abatement system used for the destruction of volatile liquid hydrocarbons, Hazardous Air Pollutants (HAPs), and Volatile Organic Compounds (VOCs). This systems is often used in place of an open flare, because it of recent regulation changes on vapor radiation and visible emissions. VCUs are considered a safer, and more economical option, than open flares. Being an innovative designer of environmental low flow, sonic, utility flare systems and more, Gulf Coast Environmental Systems can provide you with a cost effective, turn-key gas flare solution that will more than satisfy any requirements.
Carbon Absorbers are another common way to dispose of hydrocarbons. In a Carbon Adsorber, a contaminated process stream flows across an activated carbon bed. The carbon removes the VOCs from the process stream and absorbs them, holding them on the surface and in its pores. The VOC-free air is exhausted to atmosphere. Carbon is a great adsorber of organic materials like low molecular weight VOCs. When the carbon bed has reached its capacity, the concentrated VOCs are desorbed into a low pressure steam flow and either recycled or sent to a Thermal Oxidizer for destruction.
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Additional articles in the GCES series ‘Abating Hazardous Air Pollutants’ include:
Part 2: Chlorine Abatement
Part 6: SOx, the compounds of sulfur and oxygen molecules including Sulfur Monoxide, Sulfur Dioxide and Sulfur Trioxide
Part 11: Sulfuric Acid – H2SO4
Part 12: Ethylene Oxide – EtO