Construction of Desulfurization of heavy fuel oil
Energy sources with less CO2 emissions than traditional fossil fuels create more energy independence and a cleaner environment. However, even these gases have pollutants that need to be removed before they can be burned to produce electricity or combusted for vehicle operation. The good news is that the technology (desulfurization plant) makes it possible to remove sulfur compounds before energy is consumed. The Swiss company KiyaChem carries out all stages of the construction of desulphurization plants.
Desulfurization is a chemical process to remove sulfur from a material. This process can include the removal of sulfur from a single molecule or the removal of sulfur from a mixture, a mixture of crude oil mixtures. Sulfur is one of the impurities in crude oil. The presence of sulfur compounds in oils, fuels, etc. is not desirable. Also, it may cause problems during purification as well as in their commercial use. Sulfur compounds are divided into four main groups: mercaptan, sulfide, disulfide, and thiophene.
Types of technologies for desulfurization of petroleum products are as follows:
- Hydrodesulfurization (HDS): a common process used to remove sulfur compounds from oils, fuel, etc. In the hydrogen desulfurization process, metal catalysts such as nickel, cobalt and molybdenum are used at a temperature of 400 ˚C and hydrogen gas at a pressure of 100 atm. This method is used to remove aliphatic and acyclic compounds. In addition to not being used to remove large sulfur molecules, this process consumes a lot of money and energy, so it was replaced by other methods.
- Oxidative desulfurization (ODC): Oxidative desulfurization has been considered as a promising method for deep sulfur removal technology under mild conditions, which requires much lower temperature and pressure and much lower operating costs compared to the conventional hydrodesulfurization method. . The advantages of this method are small reactors, low operating cost, recyclability of solvent and oxidized sulfur. However, the low selectivity of the solvent, the low rate of catalyst regeneration and the short reaction time are among the problems of this method. Hydrogen peroxide is usually used in the presence of a catalyst, which is usually acetic acid, formic acid, polyoxometalate, or potassium superoxide. In this type of oxidation, sulfides are oxidized to sulfoxides or sulfones, which is done by using peroxyacids such as hydrogen peroxide and carboxylic acid, which is a useful method of desulfurizing oil using organic acids and hydrogen peroxide.
- Extractive Desulfurization (EDS)
- Adsorbent Desulfurization (ADS)
- Photocatalytic Desulfurization (PCDS)
- Biological Desulfurization (BDN)
- Combination of ultrasonic oxidative desulfurization and desalination (UAOD)
Among the uses of desulfurization, we can mention desulfurization of fuel oil(Mazut) and desulfurization of steel. Each of these has its own methods and advantages. In the following, we provide comprehensive explanations about heavyfuel oil(Mazut).
What is heavy fuel oil (Mazut)?
Heavy fuel oils, commonly known as HFOs, have been extensively used to power marine industry, and maritime accidents such as sinking, collisions, as well as offshore operations and routine commercial shipping activities produce spilling of heavy fuel oils into the sea. The production of environmentally friendly fuels in accordance with the global standards of emission of pollutants is of great importance in today’s world.
Iran’s power plants usually produce electricity using natural gas in most days of the year, but in winter due to the priority of urban gas supply, liquid fuel consumption in power plants increases. As a result, the amount of pollution of the power plant increases. The consumption of gasoline and heavy fuel oil (HFO), which is also called Mazut, in power plants causes the phenomenon of temperature inversion, especially in the cold seasons of the year, which has a significant effect on air pollution. According to the General Economic, Social and Environmental Administration of Renewable Energy Organization, Iran consumed 67 billion cubic meters of natural gas, 10 billion cubic meters of diesel and 5.7 billion cubic meters of HFO in power plants in 2019.
Such spillages pose several challenges from fate and transport perspective, as well as remediation techniques, since HFOs usually have relatively low API gravity values, with density values approaching (and in occasions even exceeding) the density of water. One of the main challenges related to the desulfurization of heavy fuel oil is its molecular complexity. Accurately defining the composition of crude oil is an impossible task, since it varies according to its source and the methods used for its processing, notwithstanding, some characteristics are common, indistinctively of the oil’s origin, such as the presence of asphaltenes ranging from 2.6 to 12.12 wt%, likewise a high sulfur content that can go up to 6 % by mass. In addition to marine industry, HFO is extensively used in power generation plants, especially in the Middle East region, in which the sulfur content of HFO can exceed 3.5%, which is outstandingly higher than distillate or crude oil.
The presence of metal impurities, as well as asphaltene and sulfur content reduce the combustion efficiency of HFO and lead to even higher levels of pollutant emissions during industrial activities, which decreases the commercial value of this fuel. Compounds such as thiols, thiolanes, sulfides, thiophenes, and their derivatives constitute the organosulfur compounds of petroleum fuel. The high boiling components of crude oil, which consistently become part of the residual fraction (VRO) after the distillation process in a refinery, present complex thiophene derivatives, shown in Figure. These derivatives are extremely refractory and hard to remove via conventional desulfurization processes. Since HFO is a blending product of VRO and light distillates such as diesel and kerosene, it inherits the refractory organosulfur compounds present in the residual fraction.

Mazut
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