Sulfur content reduction

HIC has been enhanced through sulfur content reduction in alloys, uniform microstructure, and controUing inclusion morphology [47]. HIC is controlled by difHisible... 

Recently, refineries finished products hydro treatment became critical due to changes in fuel regulations. These changes are related to the sp>ecification of more clean fuels with special focus in sulfur content reduction. In order to achieve these goals more hydro treatment is needed. Hydrogen is the main raw material to hydro treatment imits. 

Until 1992, the total sulfur content of jet fuel was limited to 0.2 wt. %. Starting in 1993, a reduction to 0.1% was instituted apparently without major incident since for commercial products, lower levels (to 500 ppm) had been observed very often. 

Influence of sulfur content in gasoline (from 500 to 50 ppm) in the reduction of pollutant emissions. j... 

Free sulfur is rarely present in crude oils, but it can be found in suspension or dissolved in the liquid. The crude from Goldsmith (Texas, USA.) is richest in free sulfur (1% by weight for a total sulfur content of 2.17%). It could be produced by compounds in the reservoir rock by sulfate reduction (reaction 8.2). 

The gangue content of DRI is typically comprised of oxides such as Si02, AI2O2, CaO, MgO, Ti02, K2O, Na20, MnO, etc, and is dictated by the chemistry of the iron ore used. The phosphoms in DRI is normally in the form of P2 5- Sulfur content in the DRI depends on the sulfur level in the ore and reductant, and the amount of sulfur released or absorbed by the DRI during the reduction process. 

More severe hydrotreating, such as mild hydrocracking at an H2 partial pressure of >6.9 MPa (1000 psig) and temperature of >400° C, can stiU further reduce sulfur content in the FCC feed. Mild hydrocracking of a 25° API VGO reduced the sulfur content of the FCC feed 98%, from 1.7 wt % to 0.03 wt % (40). This reduction can be expected to lower the SO content in the FCCU regenerator flue gas by about 90%. 

Sulfur Dioxide Reductant. The Mathieson process uses sulfur dioxide, sodium chlorate, and sulfuric acid to produce chlorine dioxide gas with a much lower chlorine content. The sulfur dioxide gas reductant is oxidized to make sulfuric acid, reducing the overall acid requirement of the process. Air is used to dilute the chlorine dioxide produced by this process. The exit gases flow through a scmbber to which chlorate is added in order to remove any unreacted sulfur dioxide. Spent Hquor, containing some unreacted chlorate, sulfuric acid, and sodium sulfate, continuously overflows from this process. 

The sulfur content of U.S. coals varies widely, ranging from a low of 0.2 percent to as much as 7 percent by weight, on a diy Basis. The estimated remaining U.S. coal reserves of all ranks, by sulfur content, are shown in Fig. 27-1. Extensive data on sulfur and sulfur reduc tion potential, including washability, in U.S. coals are given in Sulfur and Ash Reduction Potential and Selected Chemical and Physical Properties of United States Coal (U.S. Dept, of Energy, DOE/PETC, TR-90/7, 1990 TR-91/1 andTR-91/2, 1991). 

With higher boiling stocks, mild Hydrofining of kerosene effects desulfurization, color improvement, and a reduction in wick char. Hydrofining improves odor and by reducing sulfur content makes the kerosene less corrosive. 

The reduction of SO, is best achieved by reducing the sulfur content of the fuel oil. Ship engineers arc required to replace high-sulfur fuel with expensive higher-grade oil fuel as their ships approach coastlines where strict pollution restrictions apply. 

By 2010, Tier 2 standards should further reduce vehicle emissions by extending regulations to larger SUVs and passenger vans. The use of gasoline with a lower sulfur content will also reduce emissions and it also makes it easier to build cars that can achieve further reductions. These standards should allow new U.S. cars to be extremely free of air pollutants. But, the Clean Air Act does not cover vehicle C02 emissions. Many new cars are called near zero emissions by their manufacturers and may have tailpipe emissions cleaner than some urban air. Hydrogen fuel cell vehicles will have almost no emissions besides some water vapor and would be much cleaner. 

Many studies on the performances and emissions of compression ignition engines, fueled with pme biodiesel and blends with diesel fuel, have been conducted and are reported in the literature (Laforgia and Ardito, 1994). Fuel characterization data show some similarities and differences between biodiesel and petrodiesel fuels. The sulfur content of petrodiesel is 20 to 50 times that of biodiesel. Biodiesel has demonstrated a number of promising characteristics, including reduction of exhaust emissions. 

Hydrotreating reduces the sulfur content of product streams from sour crudes by 90% or more. Nitrogen removal requires more severe operating conditions, but generally 80% reductions or better are accomplished. 

Of the two types of SOx catalysts, the SOx additive has proven to be the more popular. Its main advantage is that it can be added to the unit at any time, and it need be added only in amounts required to give the desired degree of SOx reduction. This is especially important for units using feedstocks which vary in sulfur content. Also, use of an SOx additive does not Interfere with the... 

Reduction of residual fuel oil viscosity and sulfur content to meet specifications. 

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