The dangers of excessive sulfur content in crude oil
1. Sulfur content seriously corrodes equipment. During petroleum processing, various sulfur-containing compounds decompose under the influence of high temperature to produce H2S. When H2S coexists with water, it can cause severe corrosion to metal equipment. For example, in atmospheric and vacuum units, the corrosion of high-temperature heavy oil is mainly concentrated at the bottom of the atmospheric tower. If the oil contains both sulfur and salt, the corrosion of metal equipment will be more serious.
Sulfides in petroleum products will also corrode metals during use and storage; at the same time, sulfur dioxide and sulfur trioxide generated from the combustion of sulfur-containing fuels will produce H2SO4 and H2SO4 when they meet water, causing strong corrosion to machine parts. Sulfur in gasoline may also affect on-board advanced vehicle diagnostic systems, making them ineffective; easily wear gasoline engine cylinders and fuel pumps; and sulfur in diesel can also adversely affect engine life. As the sulfur content in diesel fuel increases, the service life of the engine decreases.
2. Sulfur content affects product quality. The existence of sulfur-containing compounds seriously affects the storage stability of oil, accelerates the oxidative deterioration of refined oil, and produces viscous deposits; sulfides can also poison and inactivate catalysts in reforming units and automobile exhaust gas purification units in the refining process.
3. Sulfur content pollutes the environment. In the process of petroleum processing, H2S and low molecular mercaptans are toxic gases with strong odor, which can cause environmental pollution and hinder human health.
The sulfur in gasoline will make the exhaust gas reformer toxic and ineffective, greatly reduce the conversion efficiency, and increase the emissions of HC, CO, and NOx; recent studies have shown that sulfur also affects vehicle emissions. Experiments show that the lower the sulfur content in gasoline, the higher the nitrogen oxide conversion efficiency of the catalyst. In order to obtain and maintain high NOx conversion, ultra-low sulfur or even sulfur-free gasoline must be used. The sulfur content in diesel fuel has a great impact on the working life of the engine. Active sulfur can directly corrode metals. When SOz and S03 produced by combustion meet the water and steam produced by combustion, sulfurous acid and sulfuric acid will be formed when the temperature is high, which will seriously corrode engine parts. When the sulfur-containing exhaust gas enters the cylinder wall and crankcase, the lubricating oil deteriorates. SOz and S03 in the gas also produce deposits in the cylinder, both corrosion and mechanical wear, and the wear caused by them is much more serious than mechanical wear alone.
In addition, the exhaust gas containing sulfide will seriously pollute the environment. For automotive diesel engines, every 0.1% increase in sulfur content increases particulate matter emissions by 0.034 g/(kW/h). When the mass fraction of sulfur in diesel was reduced from 0.3% to 0.05%, particle pollution was reduced by 9%.