دانلود مقاله ترجمه شده آسیاب گلوله ای در بهینه سازی پارامترهای فراوری شکلات – مجله الزویر

elsevier

 

دانلود رایگان مقاله انگلیسی + خرید ترجمه فارسی
عنوان فارسی مقاله: کاربرد آسیاب گلوله ای در بهینه سازی پارامترهای فراوری شکلات
عنوان انگلیسی مقاله: Optimization of processing parameters of a ball mill refiner for chocolate
دانلود مقاله انگلیسی: برای دانلود رایگان مقاله انگلیسی با فرمت pdf اینجا کلیک نمائید
خرید ترجمه آماده: برای خرید ترجمه مقاله با فرمت ورد اینجا کلیک نمائید

 

مشخصات مقاله انگلیسی (PDF) و ترجمه مقاله (Word)
سال انتشار مقاله  ۲۰۰۷
تعداد صفحات مقاله انگلیسی  ۸ صفحه با فرمت pdf
تعداد صفحات ترجمه مقاله  ۱۷ صفحه با فرمت ورد
رشته های مرتبط  صنایع غذایی
مجله  مجله مهندسی مواد غذایی (Journal of Food Engineering)
دانشگاه  دانشکده مهندسی مکانیک، میلان، ایتالیا (Dipartimento di Meccanica, Milano, Italy)
کلمات کلیدی  شکلات،فراوری آسیاب میله ای،طراحی تجربی،بهینه سازی،تابع مطلوب
لینک مقاله در سایت مرجع لینک این مقاله در سایت ساینس دایرکت
نشریه الزویر Untitled

 

 

 


بخشی از ترجمه:

 

هدف از این کار بهینه سازی آسیاب براسا فرایند فراوری و تصفیه شکلات از نظر زمان فراوری و مصرف انرژی است.آزمایش پس از طرح ریزی مرکب مرکزی(CCD) برنامه ریزی شده و با توجه به زمان فراوری(RT) و سرعت شفت همزن(as) به عنوان عوامل در نظر گرفته شده است. متغیرهای تجربی اندازه گیری ویژگی ها و شکلات های بدون قالب ریزی شده را در نظر گرفته است. مدل دوم داده ها را بررسی می کند. ضریب مصرف انرژی نیز مهم بوده و همچنین محتوای مقدار اهن و اندازه ذرات مهم است. بهینه سازی عبارتست از به حداقل رساندن زمان فراوری با استفاده از تابع مطلوب. قبل از آزمایش شرایط کار ٧٠دور در دقیقه بوده و زمان فراوری ۵٨دقیقه بوده است. شرایط مطلوب محاسبه شده توسط بهینه سازی به شرح زیر است.۵٨دور در دقیقه و ٣٨.۵ دقیقه برای زمان فراوری. شرایط کاری جدید مشخص شده برای آسیاب گلوله ای در نظر گرفته شده است که خروجی١٠٩ کیلوگرم بر ساعت تا ١۵۶ کیلوگرم بر ساعت را داشته و ۴٣%افزایش بهره وری دیده می شود. تجربه و شواهد در شرایط بهینه سازی انجام شده برای اثبات نتایج بدست آمده انتظارات موجود را از متغیر وابسته تایید می کند.
١-مقدمه:
براساس قانون فعلی اروپا Dir.٢٠٠٠٣۶/CE:UE٢٠٠٠) تهیه شکلات به عنوان یک محصول بدست امده از کاکائو و شکر است که شامل کمتر از ٣۵% مواد جامد کاکائوی بوده و مقدار کمتر از ١٨%کره کاکائو و کمتر از ١۴%کاکائوی بدون چربی خشک می باشد. روش های سنتی شکلات گیری براساس مخلوط کردن مواد تشکیل دهنده بوده و سپس انها توسط فرایند آسیاچرخشی خرد شده و کنچینگ و معتدل سازی انجام می شود. مهم تر از همه فرایند کنچینگ است که به منوظر حذف رطوبت و طعم نامطلوب می باشد. در حالی که با این فرایند شکلات بسایر دلپذیر می شود.


بخشی از مقاله انگلیسی:

 

Abstract The aim of this work was to optimize the ball mill based refining process of chocolate, in terms of refining time and energy consumption. Experiments were planned following a central composite design (CCD), considering refining time (rt) and agitator shaft speed (as) as factors. The experimental variables measured were chosen from the main characteristics that describe unmoulded chocolate. A complete second-order model was fitted to the experimental data. The most significant coefficients were that of energy consumption, iron content and particle size. Optimization consists in a bound minimization of refining time using the desirability function. Before experiments, working conditions were 70 rpm for as and 55 min for rt. The optimum conditions calculated by optimization were as follows: 58 rpm for as and 38.5 min for rt. The new working conditions identified for the ball mill considered enabled to rise output from 109 kg/h to 156 kg/h, with a 43% increase in productivity. A control experiment carried out in the optimized conditions to corroborate the results obtained, confirmed calculated expectations of response variables. Keywords: Chocolate; Ball mill refiner; Experimental design; Optimization; Desirability function 1. Introduction The current European legislation (Dir. 2000/36/CE; UE, 2000) designates chocolate as the product obtained from cocoa products and sugars, which contains not less than 35% total dry cocoa solids, including not less than 18% cocoa butter and not less than 14% dry non-fat cocoa solids. The most traditional methods of chocolate-making are based on the mixing of ingredients, grinding by roll refiners (refining phase), conching, and tempering. Above all, conching is carried out in order to remove moisture and undesirable flavours while developing the pleasant ones. In addition, since the previous grinding process will have created many new surfaces not yet covered with fat, the conching phase coats these new surfaces and improves the flow properties (Beckett, 1999). The tempering process is a technique of controlled crystallization that is necessary to induce the most stable solid form of cocoa butter (which is a polymorphic fat) in the finished product (Talbot, 1999). Chocolate refining depends on product type (milk, dark or compound), on process (crumb vs. milk powder) and on ingredients (granulated or powder sugar). Grinding operations may be evaluated on the basis of their costs (capital, maintenance and energy) and the characteristics with which they provide the product (particle size distribution, particle shape and minimization of contamination). The choice of equipment for size reduction depends on many factors, including feed and final particle size, and type of material being processed. Chocolate refining is most often carried out using a five-roll refiner. Four grinding rolls are aligned vertically, while the feed roll is placed at an angle to the lowest stack roll. The feed rate determines the throughput and the final fineness of chocolate, and is adjusted by changing the feed roll gap at a constant roll speed or by changing the roll speed at a constant gap (Ziegler & Hogg, 1999). Many minor chocolate manufacturers, in particular, require a compact chocolate-making plant that is smaller than the traditional roll refiner/conching system. Many kinds of these plants have been developed. Perhaps the most common ones are based on re-circulation through a ball mill (Beckett, 1999), which employs the relative motion of loose elements (balls) to generate a grinding action. They are typically vertical or horizontal cylinders, equipped with a rotating shaft with arms, filled to as much as 90% of the available volume with grinding media (steel balls, ceramic beads, etc.). The feed material in the form of a suspension is pumped into the grinding chamber and comminuted between the moving media, the stirrer and the grinding chamber wall by compression and shear. A temperature control system (made up of a water jacket equipped with temperature sensors and thermo-regulators controlled by electric board) allows the initial melting of solid fats, ensures that the product does not suffer thermal damage, such as a burned aroma or milk derivative decay, and it performs the substitutive action of traditional conching (Ziegler & Hogg, 1999). Since the stirred ball mills born in the first decades of 20th century as refiners for paintings, some works about their use in the mining and powder industries (Gao & Forssberg, 1995; Gao, Forssberg, & Weller, 1996; Kheifets & Lin, 1998; Ma, Hu, Zhang, & Pan, 1998; Tuzun, Loveday, & Hinde, 1995) are present in the literature. On the contrary, very few studies dealing with chocolate refining by means of ball mills have been conducted (Franke, Scheruhn, & Tscheuschner, 2002; Lucisano, Casiraghi, & Mariotti, 2006). However, the use in food industry has modified so much the machines and the process than the technologies are not anymore comparable. For this reason, even if the argumentations of existing documents are attractive, and relations among operating variables and examined physical principles are very interesting, unfortunately they are not suitable to the environment of chocolate refining. The aim of this study was to optimize working conditions of a ball mill used for chocolate refining process, in order to reduce refining time and energy consumption without forgetting the quality characteristics of the product obtained. 2. Materials and methods 2.1. Experimental design Experiments were planned following a two-factor, fivelevel central composite design (CCD), including five central points (Montgomery, 2001). The two factors (independent variables) considered were the refining time (rt = 33.7, 40, 55, 70, 76.2 min) and the agitator shaft speed (as = 41.7, 50, 70, 90, 98.3 rpm); the extreme levels of the factors were selected on the basis of previous experiments, guidance given by the ball mill manufacturers and the technical limitations of the plant. The 13 combinations obtained are reported in Table 1. The order of experiments was fully randomized to avoid systematic biases. The experimental variables measured were electricity consumption (E), particle size (d90), iron content (Fe), the Casson plastic viscosity (gCa) and the Casson yield value (sCa). Moreover, the refining time factor was also inserted as a response variables Nomenclature A current measured by the ball mill amperometer (A) as agitator shaft speed (rpm) CCD central composite design cosu constant of the electric motor (0.85) D overall desirability function d90 particle size (lm) di individual desirability function E electricity consumption (kW h) Fe iron content (mg/kg) L lower limit in the desirability function r weight assigned to each individual desirability function rt refining time (min) considered as factor RT refining time (min) considered as response variable T target value in the desirability function t0 time interval (min) in electricity consumption calculation U upper limit in the desirability function V voltage measured by the ball mill voltmeter (V) x1 value of refining time (rt) in the polynomial model x2 value of agitator shaft speed (as) in the polynomial model y experimental variable value in the polynomial model b0 constant value in the polynomial model b1, b2 linear coefficients in the polynomial model b12 interaction coefficient in the polynomial model b11, b22 quadratic coefficients in the polynomial model e random error in the polynomial model c_ shear rate (s1 ) s shear stress (Pa) gCa Casson plastic viscosity (Pa s) sCa Casson yield value (Pa) (RT) to allow the optimization of the process by the desirability function. 2.2. Chocolate production Experiments were conducted using the following formulation: 34% cocoa liquor, 17% cocoa butter, 49% icing sugar, 0.4% lecithin and 0.03% vanillin. For each experiment, a 100 kg batch of dark chocolate was produced by using as refiner a ball mill SOTUMILL/130 (Packint, Milano, Italy), constituted of a double-jacket cylinder, containing 9.5 mm diameter wear resistant steel balls and a stirring/mixing group. The vertical shaft with horizontal arms, while rotating, puts the steel balls in movement and a recycling pump recycles the chocolate mass through the ball bed. The impact between two contiguous balls or between one ball and the lateral wall of ball refiner provokes the crumbling of the particles existing in the space within the two elements. The chocolate production starts with the manual feeding of cocoa butter and liquor (both from Barry-Callebaut Italia S.p.A., Assago, MI, Italy) into the mill grinding chamber, pre-heated to 50 C. Fats were melted at this temperature for about 12 h. On the contrary, refining process was carried out at 60 C. A temperature control group, by means of a thermostat, controls that product does not suffer flavour damages. Fifteen minutes after the recycling pump is turned on, the agitator shaft starts up and this was considered the starting point of the experiment. During the first 5 min of the experiment, the icing sugar (80 lm; Gelcrem, Bareggio, MI, Italy) was gradually fed in. Lecithin and vanillin (Gelcrem) were added, respectively, 15 and 14 min prior to the end time. After the established refining time, the chocolate was discharged in a tank. The layout of the plant and a ball mill image are shown


 

دانلود رایگان مقاله انگلیسی + خرید ترجمه فارسی
عنوان فارسی مقاله: کاربرد آسیاب گلوله ای در بهینه سازی پارامترهای فراوری شکلات
عنوان انگلیسی مقاله: Optimization of processing parameters of a ball mill refiner for chocolate
دانلود مقاله انگلیسی: برای دانلود رایگان مقاله انگلیسی با فرمت pdf اینجا کلیک نمائید
خرید ترجمه آماده: برای خرید ترجمه مقاله با فرمت ورد اینجا کلیک نمائید

 

 

ارسال دیدگاه

نشانی ایمیل شما منتشر نخواهد شد. بخش‌های موردنیاز علامت‌گذاری شده‌اند *