How to control air pollution in petroleum refinery
Petroleum refineries have a tremendous effect on the environment. Oil refinery companies emit massive quantities of gases such as sulfur dioxide, carbon dioxide, nitrogen oxides, and other hydrocarbons during the refining of crude oil. All these gases are highly toxic and give rise to many environmental problems like the greenhouse effect and acid rain.
Keeping in mind the threats of air pollution, prevention and control of air pollution by petroleum refineries becomes even more crucial. Several guidelines are provided by different organizations that these companies have to follow. Different strategies and methods are used to control the impact of oil refineries on air quality. Given below is a list of a few of these methods deployed to keep a check on the air pollution created by the oil industry.
Desulfurization
Sulfur, in the form of oxides, is a gas that is said to be the leading source of air pollution. It is also the gas responsible for acid rain along with nitrogen. During the process of refining, sulfur is emitted in large quantities. Without proper control measures, this will have a huge contribution to air pollution.
One of the best methods to combat this problem is desulfurization. Desulfurization is the process of recovery of sulfur and its compounds from the gases before they enter the atmosphere. Better and inexpensive methods should be developed particularly for large-scale engine and boiler fuels.
These units will play a significant role in decreasing the amount of sulfur emissions by petroleum industries.
Vape recovery unit
A vape recovery unit is a special set-up developed to remove any undesired gases and vapors from crude oil and distillate tanks. Several variants of this unit are present and are used in multiple industry sectors.
Typically, a vape recovery unit operates on either an electric motor or a gas engine. It has four parts, namely, a gas compressor, a scrubber, a variable frequency drive, and a switching device. The compressor pulls in the liquid molecules during crude oil distillation in the scrubber where the undesired fluids are eliminated. The extracted vapor is diverted towards the gas line while the fluids towards the pipeline.
The objective of the switching device is to turn on or off the set-up automatically depending on the pressure inside the tanks.
External floating roof tank
An external floating tank is a special kind of storage tank for petroleum products. It is an open-topped cylinder with a floating roof that makes it distinct from the traditional storage tanks. The floating roof is elevated and pushed down along with the level of the liquid.
This type of storage tank was created for economical and environmental reasons. Since there is no gap between the liquid and the roof of the tank, it prevents the volatile substances in the tank from evaporating.
The external floating roof tank serves two purposes. First, this saves the wastage of the stored liquid. Second, there are some volatile air pollutants in the liquid, vapor space as present in a fixed roof tank that will cause them to escape into the environment. Conversely, a floating roof tank does not leave any vapor space and hence, helps reduce air pollution.
Catalytic reactors
Selective catalytic reduction systems, commonly referred to as catalytic reactors, are used to diminish nitrogen oxide emissions during the burning of fossil fuels. These air pollution control devices use ammonia to convert nitrogen oxides to oxygen and nitrogen. Ammonia is introduced directly in the exhaust where the conversion happens.
Besides that, additional catalysts are injected. This forces the remaining air pollutants to undergo further reduction processes through combustion. Catalytic reactions are known as one of the best ways to reduce air pollution. In the case of nitrogen oxides, it provides a 90 percent efficiency while it is even higher, 99.99 percent, for other air pollutants. Moreover, its high efficiency is accompanied by lesser energy consumption.
Although it is a highly effective device, it has its downsides. The main disadvantage of catalytic reactors is the cost of the catalyst. The catalyst needed for the reduction is usually very expensive. Also, it cannot be used to treat emissions that involve particulate matter.
Cyclone separators
As discussed above, particulate matter is an issue that catalytic reactors cannot combat. Hence, we have cyclone separators. Cyclone separators work on the process of separating particles from air, liquid, or gases.
This device sets the desired liquid or gas in a rotational motion, resembling a cyclone. The heavier particles will have a higher inertia. Hence, they are incapable of following the rotational motion and collide on the walls of the chamber and drop to the bottom. The same principle of this machine is used to separate oil and particulate matter in the gases.
Hydrocyclone separators are a type of cyclone separator that is widely used in the oil industry. There are many advantages to using it. The first and the foremost perk of using this separator is that it’s very compact. Compared to other kinds of separators, this takes about 90 percent less space. Since there is no need for any moving parts, the maintenance is reduced significantly.
Regular maintenance
Last but not the least, oil industries have to carry out regular maintenance of all the equipment and machines involved in the process. It is essential because it ensures any fault in the infrastructure of the oil company is identified before it leads to more pollution.
Checking pipelines, SS ducts, etc especially the ones carrying gases will enable them to discover any leaks and reduce the chances of contaminated air escaping into the atmosphere. It is important to do an inspection keeping in mind the age, type, and use of the pipelines because a leakage might not be noticeable at earlier stages and hydrostatic pressure testing is required to efficiently detect any issues.
Conclusion
The oil industry is a huge contributor to air pollution. The burning of petroleum substances, crude oil processing, etc. release high quantities of air pollutants. The alarming increase in environmental pollution and its effects requires some robust methods to control the air pollution caused by the oil industry. One of the best ways to do so is by making sure that the air pollutants are treated and processed before reaching the environment. Other than the devices and methods mentioned above, there are many solutions that can be deployed for the prevention of air pollution.