Cement manufacture has been one of the most energy intensive industries in the world. In order to produce clinker, rotary kilns are widely utilized in cement plants. This work deals with the energy analysis of a rotary kiln system working in a cement plant in Alburge Cement Plant (ACP), at Arab Union Cement Company (AUCC), Zliten city, Libya. The kiln has a capability of producing 4200 ton-clinker per day. The main objective of this study is to examine heat loss of various components of the rotary kiln system. In the present study, a Matlab program with a graphical user interface (GUI) has been used for energy auditing of ACP as a case study. The GUI inputs and outputs showed through the paper as an interface widows. Result shows that 30% of the total energy is being lost. An amount of 20.54% missed through hot flue gas, 5.25% across cooler stack, and 4.56% by kiln shell convection plus radiation
This volume contains contributed articles of Track 1, Track 2 & Track 3, presented in the conference CEST-2018, organized by Faculty of Engineering Garaboulli, and Faculty of Engineering, Al-khoms, Elmergib University (Libya) on 25-27 September 2018. Track 1: Communication and Information Technology Track 2: Electrical and Electronics Engineering Track 3: Oil and Chemical Engineering Other articles of Track 4, 5 & 6 have been published in volume 2 of the proceedings at this link
Factorial experimental design and response surface methodology, together with central composite design, were employed to investigate the effect of the process variables in hydrogen production via ethanol steam reforming. The influence of temperature (T), water– ethanol molar ratio (MR), and liquid hourly space velocity (SV) on hydrogen yield (
The fast reaction of forced hydrolysis of iron(111) nitrate in hypochlorite solution at room temperature, leads to the formation of mainly hematite, alpha-Fe203. Successive ion adsorption and reaction (SILAR) is applied to decorate an electrochemically formed TiO2 nanotube electrode. The anodic photo electrochemical behavior of pure TiO2-NT's and modified electrodes are investigated in a sulfate containing solution at pH =9.2. It is shown that such a modification leads to an increase of anodic photoactivity, as well as that at the same current density, the photoelectrochemical cell with a modified electrode operates at a voltage lower by 0.7 V. The band gap and flat band potentials are estimated, and the structure of the band gap and possible charge transfer reactions and mechanism are discussed. (C) 2016 Elsevier Ltd. All rights reserved.
In this work; a response surface methodology (RSM) was implemented to investigate the process variables in a hydrogen production system. The effects of five independent variables; namely the temperature (X1); the flow rate (X2); the catalyst weight (X3); the catalyst loading (X4) and the glycerol-water molar ratio (X5) on the H2 yield (Y1) and the conversion of glycerol to gaseous products (Y2) were explored. Using multiple regression analysis; the experimental results of the H2 yield and the glycerol conversion to gases were fit to quadratic polynomial models. The proposed mathematical models have correlated the dependent factors well within the limits that were being examined. The best values of the process variables were a temperature of approximately 600 °C; a feed flow rate of 0.05 mL/min; a catalyst weight of 0.2 g; a catalyst loading of 20% and a glycerol-water molar ratio of approximately 12; where the H2 yield was predicted to be 57.6% and the conversion of glycerol was predicted to be 75%. To validate the proposed models; statistical analysis using a two-sample t-test was performed; and the results showed that the models could predict the responses satisfactorily within the limits of the variables that were studied.
Catalytic systems play an important role in hydrogen production via ethanol reforming. The effect of Ni loading on the characteristics and activities of Ni/Al2O3 catalysts used in pure ethanol steam reforming are not well-understood. Two series of catalysts with various Ni loadings (6, 8, 10, 12, and 20 wt. %) were prepared by impregnation (IMP) and precipitation (PT) methods and were tested in reforming reactions. The catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), temperature-programmed reduction (TPR), and scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDAX). Powder XRD patterns of all the catalysts exhibited only NiO. Lower Ni loading catalysts were more efficient in H-2 production, as evidenced by the finding that a 6 wt. % Ni catalyst, synthesized via the PT method, yielded 3.68 mol H-2 per mol ethanol fed. The high surface area and small crystallite size of the low Ni loading catalysts resulted in sufficient dispersion and strong metal-support interactions, which closely related to the high activity of the 6 PT catalyst.
In this work, catalytic steam reforming of glycerol for hydrogen production was performed over Ce/Al2O3 and Pd/Al2O3 catalysts prepared via the impregnation method. The catalysts were characterized by scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), BET surface area, and X-ray diffraction (XRD). Two sets of catalytic reactions were conducted, one comparing 1% Pd/Al2O3 to 1% Ce/Al2O3 and the second comparing 1% Ce/Al2O3 loading to 10% Ce/Al2O3 loading. All catalytic reactions were performed using a fixed-bed reactor operated at 600 °C and atmospheric pressure. Aglycerol–water mixture at a molar ratio of 1:6 was fed to the reactor at 0.05 ml/min. In the first set of experiments, Pd/Al2O3 exhibited higher hydrogen productivity than Ce/Al2O3. A maximum hydrogen yield of 56% and a maximum selectivity of 78.7% were achieved over the Pd/Al2O3 catalyst. For the second set of experiments, the results show that the reaction conversion increased as the cerium loading increased from 1% to 10%. A total average hydrogen yield of 28.0% and a selectivity of 45.5% were obtained over 1% Ce/Al2O3, while the total average hydrogen yield and selectivity were 42.2% and 52.7%, respectively, for 10% Ce/Al2O3.
Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/AlS.G.) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/AlS.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/AlS.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.
Owing to the high energy content of hydrogen and the possibility of converting this energy in fuel cell devices into electric power without any pollutant emissions, hydrogen has grown to be one of the most useful sources of energy, especially if it is produced from renewable sources. In recent years, the development of an efficient process for hydrogen production has become an important goal for energy researchers. Numerous studies have evaluated the catalytic reforming of glycerol for hydrogen production both experimentally and thermodynamically. To enhance hydrogen production and make the production process efficient, researchers have investigated different reforming processes under a wide range of operating conditions. Moreover, the main focus of these studies was the development of a high-performance reforming catalyst that can increase the hydrogen yield and decrease carbon formation and processing costs. Several reforming processes can be used to produce hydrogen from glycerol. This article reviews these reforming processes with emphasis on the common catalysts and the operating conditions used in thermodynamic analyses and experimental work. Although most of these studies have been conducted on steam and aqueous-phase reforming processes, more work on other reforming processes, such as autothermal reforming, partial oxidation, supercritical water, and photo-catalytic reforming, has yet to be completed.
Momentous amount of glycerol is produced as a by-product during bio-diesel production by the transesterification of vegetable oils, which are available at low cost in large supply from renewable raw materials. As hydrogen is a clean energy carrier, conversion of glycerol to hydrogen is one among the most attractive ways to make use of glycerol. In this study, the catalytic production of hydrogen by steam reforming of glycerol has been experimentally performed in a fixed-bed reactor. The performance of this process was evaluated over 10wt% Ni supported alumina xerogel catalysts. Ni is impregnated over alumina xerogel which was pretreated at different temperatures of 700°C, 800°C, 900°C and 1000°C. For a comparative purpose, the steam reforming experiments were conducted under same operating conditions, i.e., reaction temperature of 600°C, atmospheric pressure and 1:6 glycerol to water molar ratio where we are getting 100% glycerol conversion in all the runs. The results showed that the hydrogen production increased with the increase in the treatment temperature of the support. The highest amount of hydrogen produced was attained over 10wt% Ni doped alumina xerogel pretreated at 1000°C. The catalytic enhancement over the best catalyst system is due to the thermal stability of the support which is treated at highest temperature. Sol gel method of preparation is implemented in the support development and different catalyst systems used in the reforming process were characterized using X-ray powder diffraction, BET surface area and SEM analysis.
Efficient catalysts for the nitration of benzene are prepared by surface capping of Ag nanoparticles using glycerol and urea with their subsequent loading over anatase titania. Herein glucose was used as an environmentally benign reducing agent for the silver ions. The catalyst was characterized and its catalytic activity was evaluated in the low temperature preparation of nitrobenzene. Ag nanoparticle loading gives rise to improved performance when compared to bare anatase titania. The influence of stabilizers and the percentage metal loading of Ag on the catalytic activity was investigated. The increased reactivity of titania seen after Ag nanoparticle loading may be due to the presence of highly dispersed nano sized surface capped Ag. Among the two capping agents studied, glycerol provides maximum efficiency for a short reaction time. These new generation catalysts appear to be an efficient alternative for the conventional use of environmentally hazardous sulfuric acid catalyst. The side reactions are found to be minimal over the present catalytic systems which lead to excellent nitrobenzene selectivity.
Glycerol, the readily available bio renewable material, is effectively utilized for hydrogen production by a steam reforming reaction. The experiments were carried out in a continuous flow fixed-bed reactor over Nickel supported alumina catalysts under atmospheric pressure at 600°C and three hours reaction time. 5%wt Ni was loaded over γ-Al2O3 and effect of promoter metals such as Fe and Co over Ni/γ-Al2O3 catalytic systems were evaluated. The catalysts were characterized by BET surface area, XRD and SEM techniques. The activity results showed that the addition of Co enhanced the catalyst performance. The catalysts exhibited a good activity and selectivity to hydrogen.
Production of hydrogen by steam-reforming of ethanol has been performed using different catalytic systems. The present review focuses on various catalyst systems used for this purpose. The activity of catalysts depends on several factors such as the nature of the active metal catalyst and the catalyst support, the precursor used, the method adopted for catalyst preparation, and the presence of promoters as well as reaction conditions like the water-to-ethanol molar ratio, temperature, and space velocity. Among the active metals used to date for hydrogen production from ethanol, promoted-Ni is found to be a suitable choice in terms of the activity of the resulting catalyst. Cu is the most commonly used promoter with nickel-based catalysts to overcome the inactivity of nickel in the water-gas shift reaction. γ-Al2O3 support has been preferred by many researchers because of its ability to withstand reaction conditions. However, γ-Al2O3, being acidic, possesses the disadvantage of favouring ethanol dehydration to ethylene which is considered to be a source of carbon deposit found on the catalyst. To overcome this difficulty and to obtain the long-term catalyst stability, basic oxide supports such as CeO2, MgO, La2O3, etc. are mixed with alumina which neutralises the acidic sites. Most of the catalysts which can provide higher ethanol conversion and hydrogen selectivity were prepared by a combination of impregnation method and sol-gel method. High temperature and high water-to-ethanol molar ratio are two important factors in increasing the ethanol conversion and hydrogen selectivity, whereas an increase in pressure can adversely affect hydrogen production.