دانلود مقاله ترجمه شده گوگرد زدایی زیستی زغال سنگ با فروشویی ستونی – مجله الزویر

فهرست مطالب:

چکیده
۱ مقدمه
۲ کار آزمایشی
۲ ۱ خصوصیات زغال سنگ
۲ ۲ آنالیز های شیمیایی
۲ ۳ کشت میکروبی
۲ ۴ روش
۲ ۵ آنالیز طیف سنجی جرمی و حرارتی
۳ نتایج و بحث
۳ ۱ اصلاح ITBW
۳ ۱ ۱ شیرابه
۳ ۱ ۲ آنالیز های زغال سنگ
۳ ۲ آنالیز های ترموگراویمتری و طیف سنجی جرمی
۳ ۲ ۱ رفتار حرارتی طی اشتعال
۳ ۲ ۲ آنالیز گاز اشتعال با طیف سنج جرمی
۴ نتیجه گیری

بخشی از ترجمه:

تصفیه  و فراوری بیولوژیکی در  اسیدیته ۱٫۳ کم تر از مطالعات دیگر بوده (اسیدیته ۱٫۵) و موجب کاهش رسوب املاح و  از این روی، افزایش  بازدهی گوگرد زدایی زیستی را به دنبال دارد زیرا  موجب افزایش سطح قابل دسترس پیریت می شود. از سوی دیگر، در  فرایند کاتالیز باکتریایی، هر دو روش واکنش مستقیم و غیر مستقیم  منجر به تولید رسوب می شوند( ۱-۲۹). با این وجود، پتانسیل اکسیداسیون و احیا شیرابه ها نشان دهنده این است که مکانیسم های غیر مستقیم زمانی غالب هستند که غلظت بالایی از آهن  انحلالی وجود داشته باشد. آنالیز طی سنج جرمی دی اکسید گوگرد در نمونه های تصفیه بیولوژیکی نشان می دهد که شدت پیک ماکزییمم (۴۸۰ درجه) برای مواد خام با تصاعد بالا در دماهای دیگر حاصل می شود. این ناشی از کاهش در مقدار پیریت و افزایش در سولفات در نمونه های گوگرد زدایی شده می باشد.
اگر زغال سنگ در دماهای بالاتر از ۱۳۰۰درجه سوخته شود، همانند آن چه که با مشعل های خاک زغالی دیده شده است، تصفیه بیولوژیکی موجب کاهش گوگرد کل تا ۲۴ درصد شده و تصاعد دی اکسید گوگرد نیز تا همین مقدار کاهش می یابد. در دماهای پایین تر این مسئله صادق نیست.

بخشی از مقاله انگلیسی:

Sulphur can be removed from coal physically, chemically or biologically. The physical methods are widely known and used, but, although they do separate much of the mineral material, their yield decreases considerably when the mineral matter in the carbon matrix is more disperse. Furthermore, they have no effect on organic sulphur [1]. Chemical methods rely on oxidizing agents [2] and alkaline and acidic solutions [3] to separate mineral matter from coal, and although yields are good (about 90% inorganic and 10% organic sulphur are removed), part of the combustible matter of the coal is lost. Consideration may be given to biodesulphurization, a biochemical reaction catalysed by aerobic microorganisms in an aqueous medium resulting in the oxidation and dissolving of the sulphur content into sulphate [4,5]. The bacterial catalysis process is characterized by a double mechanism, direct and indirect [1]. In the direct mechanism, the oxidation of sulphur to sulphate depends on a close contact between the bacteria and the surface of the pyrite in aerobic conditions, while in the indirect mechanism, the ferric ions are the primary leaching agent, attacking the pyrite and converting into sulphate and ferrous ions, to be later oxidized by the bacteria back into ferric ions. The biological method involves processes using simple installations with a low energy consumption, and eliminates both pyritic sulphur, which is finely disseminated in the carbonaceous matrix, and part of the organic sulphur [6,7]. Most of the processes studied have been carried out in a stirred reactor, giving efficiency ratings of over 90% pyritic sulphur elimination. The problems arising from this system, however, prevent its development for industrial application, especially the high energy cost of stirring [8]. It can, however, be run on a packed-bed system, which would make industrial application easier, although the residence times are longer than with stirring, and efficiency lower [9,10]. The biodesulphurization of coal is influenced by physical, chemical and biological factors. The first two sets include pH, temperature, iron concentration in the leachate, etc. and have been the objects of several studies in the last few years, both in stirred reactor process [11–۱۳] and on packed beds [9,14]. The biological factor, that is the study of the type of inoculum of microorganisms to be used and the enhancement of their activity in the process, has also been widely studied for the stirred reactor [1,15], and for the packed-bed reactor [16]. On occasions, the sulphates produced as a consequence of sulphur oxidation in the coal precipitate out onto the surface to form very insoluble salts, jarosites and others [17], whereby efficiency is lost for two reasons: firstly, the sulphur content of the coal is the same before and after the process, the difference being in its distribution under different forms, and secondly, these salts cover part of the pyrite, thus reducing the coal surface open to bacterial attack. The most important variables concerning the solubility of these salts are pH, concentrations of KC, NHC 4 , AgC, NaC, Fe3C and temperature. Nevertheless, in a packed-bed system, the ITBW (Idle Time Between Washes) should also be taken into account, as the moisture in the bed will depend on it and have a direct effect on the solubility of the salts. The ITBW will also be linked to the efficiency of coal desulphurization [14]. In previous packed-bed trials, once the desulphurization stage was over, the coal was then washed with dilute HCl to remove most of the jarosites that might have formed. Frequently this removal method was not particularly effective, and a percentage of sulphate sulphur remained on the surface of the coal as insoluble jarosites. In short, we managed to transform pyritic sulphur into sulphate sulphur but without separating it completely from the treated coal. The first aim of this study is to alter the pH and ITBW to reduce the formation. The aim of the paper is to get a better knowledge of the biodesulphurization packed-column process (mainly: transformation of pyrite to sulphates more or less insoluble, and get an insight of the fate of this components in combustion processes), and later on, scale up to a 6 ton pile, based on the results obtained. On the other hand, as during the combustion of desulphurized coal not all the sulphur salts formed decompose at the same temperature [18,19], some of these compounds may be thermally stable at the combustion temperature of coal. For this reason, the second aim of this study is to establish whether after the combustion of treated and untreated coal, the oxidized forms of sulphur are totally transformed into sulphur dioxide or a part remains in the ashes without reacting. To this end, a thermogravimetric analysis of the combustion process was carried out, and the gases produced subjected to massspectrometry analysis. 2. Experimental work Biodesulphurization was carried out in packed columns 150 cm high and 15 cm in diameter.