Removal sulfur

Sulfur from the hot fuel gas is captured by reducing it to H2S, COS, CS2, and so on. The current sulfur removal systems employ zinc-based regenerative sorbents (zinc ferrite, zinc titanate, and so on) Such zinc-based sorbents have been demonstrated at temperatures up to 650°C. Sulfur is also removed by the addition of limestone in the gasifier. This is commonly 

Manufacturer Gas Temp. (Max.) Particle Collection Efficiency Remarks 

Westinghouse Ceramic Candle Filter 1000°C 99.99% for 0.1 mm size Hanging type candles 

LLB Lurgi Lentjes Babcock Ceramic Candles Filter 1000°C 99.99% Supported both sides 

Pall Process Filtration Ceramic Candle Filter 1000°C (max.) 99.99% Supported both sides clay bonded silicon carbide filter 

Jansson et al. [189] were able to use the SX3 Biobeads and a mobile phase of dichloromethane in hexane (1 1) to make a further separation of the chloro-paraffins from lipids and other organochlorine pollutants. Using diethylhexyl phthalate (DEHP) as a marker, they collected the appropriate fractions to isolate the chloroparaffins and other pollutants. 

Elemental sulfur is present in most soils and sediments (especially anaerobic), and is sufficiently soluble in most common organic solvents that the extract should be treated to remove it prior to analysis by ECD-GC or GC-MS. The most effective methods available are (1) reaction with mercury or a mercury amalgam [466] to form mercury sulfide (2) reaction with copper to form copper sulfide or (3) reaction with sodium sulfite in tetrabutyl ammonium hydroxide (Jensen s reagent) [490]. Removal of sulfur with mercury or copper requires the metal surface to be clean and reactive. For small amounts of sulfur, it is possible to include the metal in a clean-up column. However, if the metal surface becomes covered with sulfide, the reaction will cease and it needs to be cleaned with dilute nitric acid. For larger amounts of sulfur, it is more effective to shake the extract with Jensen s reagent [478]. 

Automation does not always remove the problems of time and effort associated with manual methods. A critical evaluation of both the manual methods to be replaced and the automated alternative should be made before embarking on a new scheme. New, improved, and rapid methods described in the literature may not always be appropriate [366]. The following is a summary of the most common automation techniques. 

Regardless of the pretreatment method, simple manipulations in sample preparation remain one of the most labor-intensive areas of analytical work [491]. 

Robotic systems in a small analytical laboratory have the greatest application in the intermediate sample manipulation steps. The removal of excess solvent with the Zymark evaporator [492], for example, can be closely controlled, fully automated, and operate in parallel (up to six samples per instrument). This technique has considerable advantages over rotary evaporation, which is prone to loose volatile organic compounds (e.g., chlorobenzenes) under vacuum and rapid vaporization. Automated repetitive manipulations are well served by a robotic system [492]. 

Alkyltetralin from alkyltetrahn, linear alkylbenzene NaY t-Butylbenzene [1.2] 

Coumarone, indene from coumarone, indene, coal tar distillate NaY Toluene [12] 

5-Dichlorobromobenzene from 3,5-, 2.4-, 2,6-dichlorobromobenzene, 1.5- dichloro-2,4-dibromobenzene, m-dichlorobenzene NaX [32] 

5- Dichlorocumene from 3.5- dichlorocumene, 2.4- dichlorocumene, 2.5- dichlorocumene HKY m-Xylene [33] 

Chapters 7-10 cover the syngas purification and separation. When reforming and water-gas shift are applied to PEMFC systems, trace amounts of CO in the gas that poisons anode catalyst must be removed. This is achieved by preferential CO oxidation, which is covered in Chapter 7 by Marco J. Castaldi of Columbia 

We hope this book will provide the balanced overview of science and technology development that will facilitate the advances of hydrogen and syngas production for clean energy and sustainable energy development. 

EIA/AER. Annual Energy Review 2007. Energy Information Administration, US Department of Energy, Washington, DC. DOE/EIA-0384(2007), June 2008. 

Williams, M.C., Strakey, J.P., Surdoval, W.A., and Wilson, L.C. Solid oxide fuel cell technology development in the U.S. Solid State Ionics, 2006, 177, 2039. 

Gunardson, H. In Industrial Gases in Petrochemical Processing. New York Marcel Dekker, p. 283, 1998. 

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Cynes, B. L., Chemical Reactions as a Means of Separation—Sulfur Removal, Marcel Dekker, New York, 1977. 

Fig. 14. Coal flotation flow sheet suggested for increased sulfur removal (29). Pyritic sulfur removal from coal makes it imperative to closely control pulp...

Conversion of carbon in the coal to gas is very high. With low rank coal, such as lignite and subbituminous coal, conversion may border on 100%, and for highly volatile A coals, it is on the order of 90—95%. Unconverted carbon appears mainly in the overhead material. Sulfur removal is faciUtated in the process because typically 90% of it appears in the gas as hydrogen sulfide, H2S, and 10% as carbonyl sulfide, COS carbon disulfide, CS2, and/or methyl thiol, CH SH, are not usually formed. 

Cmde gas leaves from the top of the gasifier at 288—593°C depending on the type of coal used. The composition of gas also depends on the type of coal and is notable for the relatively high methane content when contrasted to gases produced at lower pressures or higher temperatures. These gas products can be used as produced for electric power production or can be treated to remove carbon dioxide and hydrocarbons to provide synthesis gas for ammonia, methanol, and synthetic oil production. The gas is made suitable for methanation, to produce synthetic natural gas, by a partial shift and carbon dioxide and sulfur removal. 

Because hydrocarbon feeds for steam reforming should be free of sulfur, feed desulfurization is required ahead of the steam reformer (see Sulfur REMOVAL AND RECOVERY). As seen in Figure 1, the first desulfurization step usually consists of passing the sulfur-containing hydrocarbon feed at about 300—400°C over a Co—Mo catalyst in the presence of 2—5% H2 to convert organic sulfur compounds to H2S. As much as 25% H2 may be used if olefins... 

The plant is designed to satisfy NSPS requirements. NO emission control is obtained by fuel-rich combustion in the MHD burner and final oxidation of the gas by secondary combustion in the bottoming heat recovery plant. Sulfur removal from MHD combustion gases is combined with seed recovery and necessary processing of recovered seed before recycling. 

The basic seed processing plant design is based on 70% removal of the sulfur contained in the coal used (Montana Rosebud), which satisfies NSPS requirements. Virtually complete sulfur removal appears to be feasible and can be considered as a design alternative to minimize potential corrosion problems related to sulfur in the gas. The estimated reduction in plant performance for complete removal is on the order of 1/4 percentage point. The size of the seed processing plant would have to be increased by roughly 40% but the corresponding additional cost appears tolerable. The constmction time for the 500 MW plant is estimated to be ca five years. 

Natural gas contains both organic and inorganic sulfur compounds that must be removed to protect both the reforming and downstream methanol synthesis catalysts. Hydrodesulfurization across a cobalt or nickel molybdenum—zinc oxide fixed-bed sequence is the basis for an effective purification system. For high levels of sulfur, bulk removal in a Hquid absorption—stripping system followed by fixed-bed residual clean-up is more practical (see Sulfur REMOVAL AND RECOVERY). Chlorides and mercury may also be found in natural gas, particularly from offshore reservoirs. These poisons can be removed by activated alumina or carbon beds. 

Table 3. Sulfur Removal from Organic Compounds by Hydrotreating...

Ammonia production by partial oxidation of hydrocarbon feeds depends to some degree on the gasification step. The clean raw synthesis gas from a Shell partial oxidation system is first treated for sulfur removal, then passed through shift conversion. A Hquid nitrogen scmbbiag step follows. 

Fixed-bed desulfuri2ation is impractical and uneconomical if the natural gas contains large amounts of sulfur. In this case, bulk sulfur removal and recovery (qv) in an acid gas absorption—stripping system, followed by fixed-bed residual cleanup is usually employed. 

J. B. Pheiffer, Sulfur Removal and Recovey from Industrial Processes, Hdv. in Chem. Ser. 139s American Chemical Society, Washington, D.C., 1975. 

Sources of sulfur are called voluntary if sulfur is considered to be the principal, and often the only, product. Sulfur has also been recovered as a by-product from various process operations. Such sulfur is termed involuntary sulfur and accounts for the largest portion of world sulfur production (see Sulfur REMOVAL AND RECOVERY). 

Sulfur can be produced direcdy via Frasch mining or conventional mining methods, or it can be recovered as a by-product from sulfur removal and recovery processes. Production of recovered sulfur has become more significant as increasingly sour feedstocks are utilized and environmental regulations concerning emissions and waste streams have continued to tighten worldwide. Whereas recovered sulfur represented only 5% of the total sulfur production ia 1950, as of 1996 recovered sulfur represented approximately two-thirds of total sulfur production (1). Recovered sulfur could completely replace native sulfur production ia the twenty-first century (2). 

The sulfur removed via these fixed-bed metal oxide processes is generally not recovered. Rather the sulfur and sorbent material both undergo disposal. Because the sorbent bed has a limited capacity and the sulfur is not recovered, the appHcation of these processes is limited to gas streams of limited volumetric rate having low concentrations of hydrogen sulfide. 

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