Desulfurizer process

Desulfurize the fuel. Most types of fuel can be desulfurized. However, as we go from gaseous to liquid to solid fuels, the desulfurization process becomes increasingly difficult. 

Desulfurize the flue gas. A whole range of processes have been developed to remove SO, from flue gases, such as injection of limestone into the furnace, absorption into wet limestone after the furnace, absorption into aqueous potassium sulfite after the furnace, and many others.However, the byproducts from many of these desulfurization processes cause major disposal problems. 

R. Pedroso, An Update ofithe Wellman-EordElue Gas Desulfurization Process, EPA Pub. EPA-600/2-76-136a, May 1976. 

Additionally, there are a number of useful electrochemical reactions for desulfurization processes (185). Solar—thermal effusional separation of hydrogen from H2S has been proposed (188). The use of microporous Vicor membranes has been proposed to effect the separation of H2 from H2S at 1000°C. These membrane systems function on the principle of upsetting equiUbrium, resulting in a twofold increase in yield over equiUbrium amounts. 

NaHS, marketed as 71.5—74.5 wt % flakes and 43—60 wt % Hquor ia the high purity grades, is also available as 10—40 wt % Hquor from the oil refining desulfurization process. NaHS is sold commercially ia 22.7-kg bags, 181.4-kg dmms, ia tank tmcks, and ia rail cars. 

Exhaust emissions of CO, unbumed hydrocarbons, and nitrogen oxides reflect combustion conditions rather than fuel properties. The only fuel component that degrades exhaust is sulfur the SO2 concentrations ia emissions are directly proportional to the content of bound sulfur ia the fuel. Sulfur concentrations ia fuel are determined by cmde type and desulfurization processes. Specifications for aircraft fuels impose limits of 3000 —4000 ppm total sulfur but the average is half of these values. Sulfur content ia heavier fuels is determined by legal limits on stack emissions. 

Oxidative Desulfurization Process. Oxidative desulfurization of finely ground coal, originally developed by The Chemical Constmction Co. (27,28), is achieved by converting the sulfur to a water-soluble form with air oxidation at 150—220°C under 1.5—10.3 MPa (220—1500 psi) pressure. More than 95% of the pyritic sulfur and up to 40% of the organic sulfur can be removed by this process. 

Feeds to hydrotreatment units vary widely they could he any petroleum fraction, from naphtha to crude residues. The process is relatively simple choosing the desulfurization process depends largely on the feed type, the level of impurities present, and the extent of treatment needed to suit the market requirement. Table 3-12 shows the feed and product properties from a hydro treatment unit. ... 

The latter reaction has been studied numerous times because of its relevance for the autoxidation of hydrogen sulfide in seawater and other aqueous systems [112, 113]. 8ince the polysulfide ions can be further oxidized to elemental sulfur which precipitates from the solution, these reactions are the basis for several industrially important desulfurization processes (e.g., the 8tretford, 8ulfolin, Lo-Cat, 8ulFerox, and Bio-8R processes) [114] ... 

Desulfurization processes are absolutely necessary for producing clean fuels. Possible strategies to realize ultradeep suffiirization currently include adsorption, extraction, oxidation, and bioprocesses. Oxidative desulfurization (ODS) combined with extraction is considered one of the most promising of these processes [13]. Ultradeep desulfurization of diesel by selective oxidation with amphiphilic catalyst assembled in emulsion droplets has given results where the sulfur level of desulfurized diesel can be lowered from 500 ppm to about 0.1 ppm without changing the properties of the diesel [12]. 

Effects of Sulfur Coverage. The kinetic results reported in the previous section are from reactions performed on surfaces that are initially clean. The surfaces after reaction were examined by AES and shown to be covered with carbon and sulfur at coverages close to a monolayer. It is interesting to note that although this is the case even after reaction times on the order of minutes the reaction rate is constant for a period of approximately one hour. Either the reaction is occurring on top of this oarbon/sulfur layer or these species are present as sulfur containing hydrocarbon fragments that are intermediates in the desulfurization process. 

Sweetening of petroleum products implies the removal of dissolved free sulfur and its compounds like hydrogen sulfide, and mercaptans in order that the product has no bad odour and does not tend to cause corrosion. The removal of these is accomplished by oxidation processes, solvent processes or catalytic desulfurization processes. 

Barometric condenser wastewater from the crystallizer, the final coolers, light oil recovery operations, ammonia still operation, coke oven gas condensates, desulfurization processes, and air pollution control operations... 

Valentine [61] also disclosed the use of R. rhodococcus ATCC 53968 for a desulfurization process of emulsified bitumen. The variety of possible biocatalyst types include... 

Recent work at Diversa [219] investigated use of alternate Rhodococcus strains as hosts for desulfurization genes. It was reported that R. opacus was the most suitable for the application. This was due to its ability to grow fast and use triglycerides as carbon source for production of reduced co-factors during the desulfurization process. 

Improving stability of microbial strains in organic solvents is another challenge for enabling commercialization of desulfurization processes for gasoline and diesel applications. This was a target for a project in Klibanov s group [231], whose approach... 

In this subsection, specific operating parameters will be discussed. These includes nutrient media for use during desulfurization process, toxicity of solvent to various biocat-alytic strains, effect of oil/water ratio on biocatalyst as well as desulfurization rates and subsequent separations, biocatalyst density during desulfurization, and finally, the alternative to operate the desulfurization process in batch vs. continuous mode. 

Anaerobic desulfurization process for crude oil and petroleum products [1],... 

The desulfurization process reported by the authors was a hybrid process, with a biooxidation step followed by a FCC step. The desulfurization apparently occurs in the second step. Thus, the process seems of no value, since it does not remove sulfur prior to the FCC step, but only oxidizes it to sulfoxides, sulfones, or sulfonic acids. The benefit of such an approach is not clearly outlined. The benefit of sulfur conversion can be realized only after its removal, and not via a partial oxidation. Most of the hydrotreatment is carried out prior to the FCC units, partially due to the detrimental effect that sulfur compounds exert on the cracking catalyst. It is widely accepted that the presence of sulfur, during the regeneration stage of the FCC units, causes catalyst deactivation associated with zeolite decay. In general terms, the subject matter of this document has apparent drawbacks. 

Shell s microbiological desulfurization process is carried out by mixing coal with an aqueous biocatalyst solution [158], The coal considered in this invention concerns bituminous coal containing inorganic sulfur (pyritic).This process seems to be applicable to refinery pet-coke, which contains sulfur in the form of inorganic sulfides. Nowadays, when coke has become one of the major products of heavy oil and bitumens refining, such desulfurization processes might have potential uses. 

The desulfurization process can be carried out either, in a dedicated reactor, or within a simple storage vessel, or during transportation (in pipelines) or intermediate processing vessels. Nutrients addition, pH, and aeration are adjusted as necessary. Multiple stages can be added to the reaction to enhance the sulfur removal process and decrease the reaction time below the probable 300 h required. The produced sulfates are removed by the addition of agents such as alkaline calcium, magnesium, aluminum, barium, and metal compounds such as oxides, hydroxides, and carbonates. 

Biocatalyst regeneration can be envisioned to be more than just co-factor regeneration. This may include induction and production of desulfurization enzymes during the desulfurization process or reproduction of new cells. Neither of these issues has been looked... 

ADVACATE A flue-gas desulfurization process, similar to CZD, but using a suspension of fly-ash instead of lime. Developed by the University of Texas, the U.S. Environmental Protection Agency, and Acurex Corporation. 

ASARCO [American Smelting and Refining Company] This large metallurgical company has given its name to a flue-gas desulfurization process in which the sulfur dioxide is absorbed in dimethylaniline and subsequently desorbed at a higher temperature. Operated in California, Tennessee, and Norway. 

Battersea A pioneering flue-gas desulfurization process, operated at Battersea power station, London, from 1931 until the station was closed. The flue-gases were washed with water from the River Thames whose natural alkalinity was augmented by chalk slurry. One of the problems of this process was cooling of the stack gases, which caused the plume to descend on the neighborhood. 

Bergbau-Forschung/Uhde A flue-gas desulfurization process that uses a movable bed of hot coke. Operated in a power station in Arzberg, Germany, since 1987. 

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