Sulfur removal hydrogen concentration effects

The CNG acid gas removal process is distinguished from existing AGR processes by three features. The first feature is the use of pure liquid carbon dioxide as absorbent for sulfurous compounds the second feature is the use of triple-point crystallization to separate pure carbon dioxide from sulfurous compounds the third feature is the use of a liquid-solid slurry to absorb carbon dioxide below the triple point temperature of carbon dioxide. Pure liquid carbon dioxide is a uniquely effective absorbent for sulfurous compounds and trace contaminants triple-point crystallization economically produces pure carbon dioxide and concentrated hydrogen sulfide for bulk carbon dioxide absorption the slurry absorbent diminishes absorbent flow and limits the carbon dioxide absorber temperature rise to an acceptable low value. The sequence of gas treatment is shown in Figure 1, an overview of the CNG acid gas removal process. 

The effect of added hydrochloric acid concentration was studied in order to determine whether or not the acid had any effect on pyrite and ash removal, sulfate-to-sulfur ratio, final heat content, and possible chlorination of the coal. Coal has many basic ash constituents, so increased ash removal was expected, as well as some suppression of the sulfate-to-sulfur ratio because the reaction that results in sulfate formation also yields eight moles of hydrogen ion per mole of sulfate (common ion effect). Added acid was studied in the range of 0.0 to 1.2M (0.0, 0.1, 0.3, and 1.2M) hydrochloric acid in 0.9M ferric chloride. Duplicate runs were made at each concentration with all four coals for a total of 32 runs. The results showed no definite trends (except one-uide infra) even when the data were smoothed via computer regression analysis. Apparently the concentration range was not broad enough to have any substantial effect on the production of sulfate or to cause the removal of additional ash over that which is removed at the pH of IM ferric chloride ( pH 2). 

Phenomena. In the first step, one could clearly look at aggressive effects - the well-known phenomena of acidic and basic solutions. Concerning acids, one can demonstrate the spectacular reaction of concentrated sulfuric acid with sugar (see E7.1) or that of the behavior of acidic solutions with metals (see E7.2). One should discuss, in both cases, the statement that an acid is something which eats material away [5], and can demonstrate that other substances are produced by those acid reactions sulfuric acid and sugar produce black carbon and steam metals react to produce hydrogen and a salt solution, from which solid white salts may be obtained by the evaporation of water. In addition, acidic household cleaners like those that remove lime deposits could be introduced one could demonstrates that when lime deposit is removed by a cleaner solution, salt solution and carbon dioxide gas are produced (see E7.3). 

The oxime is obtained by the action of hydroxylamine hydrogen sulfate on cydododecanone. This operation takes place in a solvent that is immisdble with water or with concentrated sulfuric add, which are used in the next step. The most widely used solvent is isopropylcydohexane (or hydrocumene) which dissolves the oxime at the reaction temperature of 100 G Conversion is practically quantitative. It takes place in a series of reactors equipped with effective agitators, into which aqueous solutions of hydroxyl-amine sulfate are introduced, together with ammonia to keep the pH about 7. The effluent is cooled aad settled. The aqueous layer containing ammonium Sulfate is removed. The organic phase is washed with concentrated sulfuric add. The oxime sulfate solution... 

In view of the uncertainties inherent in Hammett indicator determinations of surface acidity by visual means, a study was made of the spectral behavior of dyes adsorbed on several silica-alumina catalysts and silica gel (62). The effects of catalyst water content, dye concentration, catalyst composition and pretreatment on the spectra of the adsorbed dyes were examined. The Hammett indicator dyes employed and their corresponding pKA values are summarized in Table II. Reference spectra were determined for the base-form of the dye in iso-octane or methylene chloride solution and for the acid-form in an aqueous sulfuric acid or ethanolic-hydrogen chloride solution. Dyes were adsorbed from isooctane solutions onto thin plates of optically transparent catalysts which were installed in evacuated cells of design similar to that shown in Fig. 4. The catalysts samples were routinely pretreated by calcination in oxygen at 500° to remove any organic contaminants, followed by evacuation at this temperature. To examine the effect of variable water content on the spectra the samples were rehydrated in an atmosphere of wateir vapor for 24 hr after pretreatment and subsequently evacuated at some lower temperature. Dye solutions were introduced through a side arm. These solutions were suitably dilute so that the absorbance due to dissolved dye was either below the limits of detection or, at... 

---