Asphalt's Role In Diesel: Sulphur's Replacement Explored

Sulphur is naturally present in crude oil, which is the origin of diesel fuel. However, it is not a component of pure and ideal diesel fuel. Since 2006, almost all petroleum-based diesel fuel available in Europe and North America has been of the ultra-low-sulfur diesel (ULSD) type. This transition to ULSD was driven by the implementation of environmental regulations to reduce harmful emissions from diesel combustion. Sulphur was replaced with asphalt in diesel fuel because, in addition to being harmful to humans, it can also cause fuel pump failures in certain engines.

Sulphur is not a lubricant but its removal also removes substances that are lubricants

Sulphur is not a lubricant. It is harmful to humans and the environment, and it is, therefore, removed from diesel fuel during the refinement process. However, the process of removing sulphur also removes other substances that do provide lubrication.

Sulphur is a naturally occurring element in crude oil, which diesel fuel is derived from. The refining process may not assure the complete removal of sulphur in the final fuel. Sulphur has to be scrubbed out of the exhaust by the catalytic converter. Advanced nations aim to rid diesel of sulphur because it is harmful to humans. Sulphur can also be harmful to engines, shrinking gaskets and seals, particularly in VWs.

The most cost-effective way to remove sulphur from fuel is through a chemical process called hydro-processing. During hydro-processing, the sulphur in the fuel is replaced by hydrogen, resulting in a cleaner-burning fuel with improved performance. However, hydrogen is a highly reactive element, and it also reacts with other components in the fuel, removing the polar and aromatic compounds that provide conventional diesel fuel with adequate lubricating capability.

All diesel injection equipment relies on diesel fuel as a lubricant. In modern common rail injection systems, the rotary and distributor type of fuel injection pumps are often lubricated by the fuel. Other components such as injectors, unit injectors, unit pumps, and in-line pumps typically consist of a plunger or needle operating in a sleeve or bore and are boundary lubricated.

The loss of lubricity caused by the removal of sulphur can result in increased emissions through wear. This means that, ironically, as sulphur levels have decreased, so too has the lubricity. A lack of lubricity can lead to increased emissions through wear, increased fuel consumption from excessive pump wear, and even potential catastrophic failure.

Lubricity can be restored using lubricity-improving additives. The International Council on Combustion Engines (CIMAC) advises on how to deal with engines running on low-sulphur fuel, stating that lubricity characteristics can be restored using these additives.

Sulphur removal reduces fuel's lubricating properties

Sulphur is not originally a part of a pure and ideal diesel fuel. It is derived from crude oil, which contains a considerable percentage of sulphur compounds. The refining process may not assure the complete removal of sulphur in the final fuel. However, sulphur removal is necessary to obtain green fuel oil.

The combustion of fuel oil leads to the production of hazardous materials, including sulphur-containing compounds, which are unfriendly to human beings and the environment. Sulphur removal from fuel oil has become a priority in the refining industry to achieve a safe and sustainable environment.

The removal of sulphur compounds found in transportation fuel and other petroleum products is necessary and has drawn tremendous attention from both oil-exporting and oil-importing countries. The combustion of fuel oil leads to the production of hazardous sulphur-containing compounds, which are toxic and the main cause of environmental contamination.

The process of removing sulphur also removes other substances that provide lubrication. However, lubrication is added back after the sulphur is removed. Sulphur does not provide lubrication itself, but it can help add lubricity.

The regulatory bodies have imposed restrictions and stringent regulations on the permissible limit of sulphur in fuel oil to protect the environment from hazardous pollutants. Developed nations, in particular, have set standards to limit the amount of sulphur allowable in diesel and oil fuel.

Diesel fuel is illegal as an asphalt release agent under 3 federal laws

Diesel fuel is illegal as an asphalt release agent (ARA) under three federal laws: the Oil Pollution Act of 1990, the Clean Water Act of 1972, and the Resource Conservation and Recovery Act. These laws impose hefty fines on contractors found using diesel fuel as an asphalt release agent.

The use of diesel fuel as an ARA is banned due to safety, health, and environmental concerns. With a flash point of around 125-130°F, diesel fuel quickly vaporizes and releases highly combustible fumes that pose a risk of explosion, damaging equipment, and endangering workers. It is also a health hazard, with over 40 toxic compounds that affect the respiratory system and increase the risk of heart problems, lung cancer, and premature death.

In addition, diesel fuel ruins asphalt integrity. It strips asphaltic cement from the aggregate, causing crumbling, cracking, and reducing the pavement's lifespan. It also fails to prevent buildup effectively, requiring frequent reapplication and increasing costs.

As a result, alternative products like PavePro offer a safer, more effective, and environmentally friendly solution for the paving industry.

Diesel fuel is highly combustible and dangerous

The flash point of diesel fuel, or the minimum temperature at which it generates enough vapours to cause ignition, is between 37 and 82 degrees Celsius (100 to 180 degrees Fahrenheit). This falls within the range of less than 93 degrees Celsius (199.4 degrees Fahrenheit), which is the threshold for a flammable liquid according to the U.S. Occupational Safety and Health Administration.

The combustibility of diesel fuel poses potential hazards for fire or explosion, as well as risks to individuals' health and the environment. When ignited, diesel fuel emits toxic fumes and fine particles that can cause respiratory problems and other health issues. Prolonged exposure to diesel exhaust is associated with lung irritation, respiratory illnesses, and an increased risk of cancer.

In addition to its health hazards, diesel fuel also poses safety risks in work environments, especially where sparks or open flames are present. It is important to keep ignition sources away from diesel fuel and to handle and store it with safety precautions in mind.

Furthermore, diesel fuel is derived from crude oil, and its combustion releases harmful greenhouse gases and pollutants into the atmosphere, contributing to air pollution, climate change, and negative impacts on human health and the ecosystem.

Diesel fuel is short-lasting

The quality of diesel fuel can be severely impacted by three main factors: hydrolysis, microbial growth, and oxidation. Hydrolysis occurs when diesel is exposed to water, causing a chemical reaction that breaks down the fuel and makes it susceptible to microbial growth. Microbes produce acids that degrade diesel, clog filters, restrict fluid flow, corrode tanks, and damage engines. The risk of microbial growth is increased by the presence of water and is a result of the Environmental Protection Agency's (EPA) mandate to reduce sulfur in diesel fuel. While this mandate aims to decrease air pollutants, it has the unintended consequence of making diesel fuel less stable.

Oxidation is another factor that contributes to the short lifespan of diesel fuel. It is a chemical reaction that occurs when diesel fuel is exposed to oxygen, leading to the formation of high acid values, gum, sludge, and sediment. The acid corrodes the tank, while the gum and sediment clog filters. To prolong the life of diesel fuel, it is crucial to maintain a cool temperature of around 70 degrees Fahrenheit and treat it with biocides and stabilizers.

Additionally, the flash point of diesel fuel is important to consider. When diesel fuel comes into contact with hot metal, such as during the asphalt paving process, it immediately starts to steam and evaporate. This reduces its effectiveness as a release agent and requires a higher quantity of product to be used, increasing costs.

In summary, diesel fuel is short-lasting due to its susceptibility to contamination, hydrolysis, microbial growth, and oxidation. These factors, along with its high flash point, contribute to a reduced storage life and the need for frequent reapplication in certain industrial processes.

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