بهینه سازی فرآیند پیرولیز سریع ضایعات نیشکر به کمک روش سطح پاسخ

در حال حاضر زیست‌توده به عنوان منبعی اقتصادی و تجدید پذیر مورد توجه بسیاری از محققان قرار گرفته است. تولید زغال زیستی از منابع زیست‌توده می‌تواند علاوه بر تولید انرژی از این منابع، از اثرات مخرب زیست محیطی ناشی از استفاده بی رویه سوخت‌های فسیلی نیز بکاهد. در این تحقیق به بررسی فرآیند پیرولیز در حضور آب در شرایط بحرانی، دما و فشارهای بالا که به اصطلاح کربونیزه کردن هیدروترمال می‌نامند، جهت تولید زغال زیستی از باگاس نیشکر که از ضایعات نیشکر می‌باشد، پرداخته شد. عوامل مورد مطالعه در این تحقیق شامل زمان ماند مواد درون رآکتور (30، 75 و 120 دقیقه)، نسبت جرمی باگاس به آب (0.15 ، 0.20 و 0.30) و فشار درون رآکتور (10، 12.5 و 15 بار) بود. در این تحقیق از روش باکس بنکن به منظور طراحی آزمایش‌ها استفاده شد و همچنین جهت یافتن شرایط عملکردی رآکتور از روش سطح پاسخ استفاده گردید. بر اساس نتایج بدست آمده، میزان نسبت جرمی باگاس به آب معادل 0.15، زمان ماند 38 دقیقه و فشار11 بار به عنوان نقطه بهینه عملکردی سامانه پیرولیز سریع انتخاب شدند. برای این نقطه بهینه، میزان ارزش حرارتی بالای نمونه‌ها معادل mj/kg 21 و میزان انرژی مصرفی سامانه برابر kwh 0.09 به دست آمد.

Optimization of sugarcane bagasse fast pyrolysis conditions using response surface method

IntroductionToday, with advances in all sciences, we must always look for a way to make the best use of plant residues and turn them into valuable products. A consequence of improving family life standards and consistent industrial development is a higher demand for energy usage. Nowadays, agricultural residues are produced in huge quantities and could be considered as a promising source for renewable energy generation. Bagasse is one of the major sources of sugarcane production. The production of valuable products from Bagas, in addition to having economic benefits, can reduce the environmental damage caused by burning them. In recent years, there has been an increasing trend in the utilization of sugarcane bagasse as a major byproduct of the sugarcane industry. Another very valuable substance produced from sugarcane bagasse, which we will discuss in this study, is bio compressed coal. Valorization of sugarcane bagasse to engineered biochar using hydrothermal carbonization (HTC) presents a perspective source to substitute conventional fossil fuels. HTC process offers the benefits of converting the sugarcane bagasse into biochar and biooil. In this process, biomass is usually conducted in the temperature range of 180–250 ◦C. HTC technique is promoted as one way of reducing carbon dioxide (CO) emissions, which mostly generated through open burning of crop residues. Besides the utilization for power/heat generation for sugarcane industries, Bagasse may find other potential applications, for instance: electricity generation, biogas production, livestock feed/compost production, and also bioethanol production. The unique features of biochar generated through HTC process are its portability, high volumetric energy density, hydrophobicity, and wear ability. Materials and MethodsIn this research, sugarcane waste was obtained from Hakim Farabi Sugarcane Cultivation and Industry Company in Ahvaz. The hydrothermal carbonization process was performed in a batch reactor at Shahid Chamran University of Ahvaz. The parameters studied in this study include the retention time of the material inside the reactor (30, 75, and 120 minutes), bagasse mass to water ratio (0.15, 0.20, and 0.30) and the pressure inside the reactor (10, 12.5 And 15 bar). In order to measure the pressure, a Nuova FiMa barometer was used, which was able to measure the pressure values up to 25 bar. A temperature control system model HANYoung ED6 was used, which was equipped with a ceramic heater with a diameter of 230 mm and a height of 230 mm to provide heat for the process. The PARR1266 calorie bomb device was employed to measure the calorific value of the samples. The moisture content of the samples was also measured using ASTM2010a standard. In this experimental work, the response surface method was employed to investigate the effect of input parameters (i.e., pressure, residence time, and watertobiomass) on the response parameter (i.e., HHV and energy consumption). Design Expert ver.10 software was used to predict the corresponding models. The obtained models provided a good relationship between the independent/dependent parameters. Results and DiscussionThe HTC process has been analyzed using a Response Surface Method to derive predicted models for the HHV and energy parameters. The results obtained showed that all models provided could successfully predict the HTC process. According to the results, the models developed were statistically significant at the level of 1%. The multiregression models between the input/response variables were obtained as secondorder quadratic equations. The Fvalue for the residence time, and waterto bagasse, and pressure were 2417, 286, and 1185, respectively. The value of Fvalue of each derived model indicates the significance of the studied parameters. The parameters of watertobagasse and pressure had a more significant effect compared to the residence time factor. The Rsquare value for this study was achieved as 0.0996, indicating that the proposed model was able to evaluate the experimental data thoroughly. A multiobjective optimization technique was used to achieve an optimal HTC process condition with the maximum possible amount of desirability value. ConclusionThe optimum amount of watertobagasse, pressure, and residence time was calculated using the response surface techniques. A pressure of 11 bar, the residence time of 38 min, and watertobagasse of 0.15 were found to be optimal values. The findings of this study indicate that at optimal input variables, the value of calorific value and used energy was 21 Mj/kg and 0.09 kWh, respectively. Keywords: Hydrothermal carbonization, Sugarcane bagasse, Response surface method, Optimization