Energy, water and process technologies integration for the simultaneous production of ethanol and food from the entire corn plant

This paper presents simultaneous integration of different technologies such as the traditional dry-grind process to obtain ethanol from grain with the gasification of the corn stover followed by either syngas fermentation or catalytic mixed alcohols synthesis. The optimal integrated process when using the entire corn plant (18 kg/s of grain and 10.8 kg/s of stover) is the one in which the dry-grind technology to process corn grain is integrated with the catalytic path for the corn stover due to the improved integration of energy, requiring only 17 MW of energy, 50 MW of cooling and 1.56 gal/gal of freshwater, for an ethanol production cost of 1.22 $/gal. However, the production cost decreases as we only use stover to produce ethanol, while the grain is used for food due to the lower cost of the stover and the more favorable energy balance of the ethanol production process from gasification.     

电渗析技术在木糖醇酸水解法制备中的应用

木糖醇作为一种可作为甜味剂的糖醇具有广泛的应用前景。目前工业上酸水解法制备木糖醇的过程中需要一个脱除水解液中的残酸的工艺步骤。传统的残酸去除方法为饱和石灰水中和法,存在能耗高、消耗的化学试剂多、污染大等缺点。为实验木糖醇的清洁生产,本文采用自我组装的电渗析装置对木糖水解液中的残酸进行了选择性的去除,考察了操作电流对残酸去除及木糖得率的影响。结果表明,当操作电流为30 mA·cm^-2时,电渗析过程对残酸的去除率大于99%,其木糖的得率为84.9%,电渗析工艺处理木糖水解液的能耗为179 kW·h·t^-1,脱酸工序成本为每吨母液139元,具有良好的经济效益和环境效益。由此可见,电渗析工艺在木糖醇酸水解法制备过程中具有广泛的应用前景。     

Synthesis and charge/discharge properties of cellulose derivatives carrying free radicals

Ethyl cellulose derivatives [EC-T and EC-P] and cellulose acetate derivatives [CA-T and CA-P] carrying TEMPO or PROXY radicals (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyloxy, PROXY = 2,2,5,5-tetramethyl-1-pyrrolidinyloxy) were synthesized with moderate number-average molecular weights of 62?400-126?000 in 84-88% yield by the reaction of 4-carboxy-TEMPO or 3-carboxy-PROXY with residual hydroxyl group of ethyl cellulose or cellulose acetate. All the free radical-containing cellulose derivatives demonstrated reversible charge/discharge processes, whose discharge capacities were 42.8-61.1 A h/kg. In particular, the CA-T-based cell displayed two-stage discharge process, and the first-stage discharge capacity reached 29.5 A h/kg which corresponds to 74% of its theoretical value, and that of the total capacity was 61.1 A h/kg which approaches up to 153% of the theoretical value for one-electron redox reaction.     

Extrusion-cooking of starch protective loose-fill foams

One of the most interesting alternatives to EPS is extrusion of starch-based materials. TPS-based biocomposites can be processed, in a one-step process, via an extrusion-cooking. Wide program of the experimental works with application of extrusion-cooking for production of starchy loose-fill foams has been started in the Department of Food Process Eng., Lublin University of Life Sciences in 2012. The object of the study is to achieve commercially acceptable biodegradable products based on locally produced potato, corn and wheat starch, which can replace popular EPS. Results of the first phase of the study are presented in the paper. The measurements of glass transition temperature of TPS samples showed that with glycerol content growth in the blend, the Tg of the obtained material decreases almost linearly. In the case of potato TPS, the highest observed Tg was 187.7 ?C for 7.0% glycerol and the lowest was at 18.1 ?C for 30% glycerol. Properties of the loose-fill foams highly depend on raw materials and process parameters used in production. In addition of plasticiser or other additives, different temperature of processing is causing changes in product's properties. All starch-based foams had high open-cell content and the expansion was attributable to the escape of water as steam during processing, resulting more than 80% open cells. The foam density of starch-based products ranged between 18.7 and 30.5 kg/m³. The products were at least 2.5 times more dense than EPS-based foams. The best products achieved by us up till now are the corn TPS-based foams containing 3% plasticizer and 1% poly-vinyl alcohol. The energy consumption during extrusion-cooking depended on the material composition of the blends, temperature and the screw rotation speed used during processing. Average value of SME was about 2.52 × 10⁵ J/kg, which is equivalent to 0.07 kW h/kg.     

Electrophoretic deposition (EPD) of hydrous ruthenium oxides with PTFE and their supercapacitor performances

The effect of PTFE addition was investigated for the electrophoretic deposition (EPD) of hydrous ruthenium oxide electrodes. Mechanical stability of electrode layers, together with deposition yield, was enhanced by using hydrous ruthenium oxide/PTFE dispersions. High supercapacitor performance was obtained for the electrodes prepared with 2% PTFE and 10% water. When PTFE content was higher, the rate capability became poor with low electronic conductivity; higher water content than 10% resulted in non-uniform depositions with poor cycleability and power capability. When electrodes were heat treated at 200 °C for 10 h, the specific energy was as high as 17.6 Wh/kg based on single electrode (at 200 W/kg); while utilizable energy was lower with heat treatment time of 1 and 50 h, due to the high resistance and gradual crystallization, respectively. With PTFE addition and heat treatment at 200 °C for 10 h, the specific capacitance was increased by 31% (460 → 599 F/g at ca. 0.6 mg/cm²) at 10 mV/s, and the deposition weight was increased up to 1.7 mg/cm² with initial capacitance of 350 F/g.     

Determination of optimal pre-treatment conditions for ethanol production from olive-pruning debris by simultaneous saccharification and fermentation

Ethanol generation from lignocellulose materials provides an alternative energy-production system. This study investigates the effect of pre-treatment conditions: maximum temperature (range 423.15-483.15 K) and sulfuric-acid concentration (interval 0.002-0.059 kmol/m³) on fuel-ethanol production from simultaneous saccharification and fermentation (SSF) of olive-pruning debris by Saccharomyces cerevisiae IR2-9a (a thermal acclimatized microorganism, 313.15 K). The influence of these two variables was determined by using a response-surface methodology. Cellulose percentage in pre-treated solids reached a maximum of 71.6% of the content in raw material at 483.15 K and 0.010 kmol/m³ of acid concentration. The conversion of hemicellulose into monosaccharides and oligosaccharides also was analyzed. After the wash and filtration of solids, a significant quantity of d-glucose was obtained in the liquid fraction. For ethanol generation, the bio-fuel yield (maximum of 9.6 kg from 100 kg olive-pruning debris), and volumetric ethanol productivity (maximum of 0.27 kg/(m³ h)), strongly depended on pre-treatments conditions. According to statistical optimization, the highest ethanol yield (9.9 kg ethanol from 100 kg olive-pruning debris) is achieved at 480.15 K using a catalyst concentration of 0.016 kmol/m³. A maximum overall process yield of 15.3 kg ethanol/100 kg olive-pruning debris may result when taking into account ethanol from SSF and d-glucose present in the pre-hydrolysate, assuming its theoretical conversion (22.8 kg ethanol/100 kg raw material, also considering the total conversion of d-xylose in the filtrate).     

Production of isopropyl palmitate in a catalytic distillation column: Experimental studies

The fatty acid esters produced using monohydric alcohols have a wide range of applications in the cosmetic and personal care products. The conventional method for the production of esters has several drawbacks such as product quality degradation due to relatively long exposure to heat, necessity of catalyst neutralization and relative high alcohol demand. The reactive distillation (RD) process for the production of fatty acid esters overcomes these drawbacks. The production of isopropyl palmitate (IPP) in the RD column is reported in the present study. The reaction was catalyzed by the zinc acetate supported on silica gel. A pilot plant RD column of 102 mm diameter with a packing height of 3 m was designed, fabricated and used for the experimental studies. The process parameters total feed flow rate (30-100 mol/h), reboiler duty (0.5-2.0 kW), palmitic acid (PA) feed composition (40-100 mol%), PA feed temperature (80-), molar ratio of isopropanol feed to PA feed (1-2) and reflux ratio (0.5-2.5) were varied during the experimental study. The experimental optimum values of these parameters obtained were 50 mol/h, 0.64 kW, 100 mol%, 120^°C, 2 and 0.5, respectively within the range of study. The average IPP purity of 86 mol% and PA conversion of 94% were obtained at the optimum operating conditions. The experimental data were used to validate the theoretical predictions obtained from steady-state model and rate-based model. The predictions from the rate-based model matched with the experimental results qualitatively and quantitatively.     

Thermo pervap: The next step in energy efficient pervaporation

Thermo pervaporation (PV) is a pervaporation process that makes use of low quality heat to recover or purify solvents from water. Based on this technology it is possible to integrate the condensation energy for the direct heating of the feed during pervaporation in one single module.This concept was experimentally investigated for the separation of ethanol from a mixture of ethanol-water. It was possible to obtain a heat recovery of 33% (meaning that 33% of the heat transferred to the feed stream is condensation heat) and fluxes up to 0.5 kg/m² h at high ethanol concentration.     

Flexible and cost-effective optimization of BOG (boil-off gas) recondensation process at LNG receiving terminals

In view of high energy consumption and poor flexibility in boil-off gas (BOG) recondensation operation at liquefied natural gas (LNG) terminals, a flexible and cost-effective optimization including the control system and flow process has been proposed. The optimized control system maintains BOG recondenser pressure via the condensing LNG flow and recondenser liquid level via bypass LNG flow. A BOG recondensation process with pre-cooling operation utilizes high-pressure pump LNG to pre-cool compressed BOG before it is directed into recondenser. The engineering application in a case of 6.69 tons/hour (t/h) BOG and LNG output fluctuating between 49 t/h and 562 t/h shows, after the flexible and cost-effective optimization, that process energy decreases 91.2 kW, more 1.28 t/h BOG is recovered when LNG output load reaches the valley, and the operation stability is well improved.     

Optimization of baker's yeast drying in industrial continuous fluidized bed dryer

Instant active dry baker's yeast is a well-known product widely used for leavening of bread, produced by fermentation, and usually dried by hot air to 94-96% dry matter content. Multi-stage fluidized bed drying process is a commercial effective method for yeast drying. In this work, optimum operating parameters of an industrial continuous fluidized bed dryer for the production of instant active dry yeast were investigated. The dryer contained four zones separated with moving weirs. The operating conditions such as temperature, loading rate of compressed yeast granules, and hot air humidity had direct effects on both yeast activity and viability. The most important factors that affected the quality of the product were loading rate and the operational temperature in each zone on the bed. Optimization was performed for three loading rates of the feed to the dryer, using response surface methodology for the experimental design. The most significant factor was shown to be the loading rate with mean fermentation activity values of 620, 652, and 646 cm³ CO₂/h for 300, 350, and 400 kg/h loading rates, respectively. The data analysis resulted in an optimal operating point at a loading rate of 350 kg/h and temperatures of zones 1, 2, 3, and 4 controlled at 33, 31, 31, and 29 °C, respectively. The best activity value was predicted as 668 ± 18 cm³ CO₂/h, and confirmation experiments resulted in 660 ± 10 cm³ CO₂/h. At the same operating point, the average viability of the cells was predicted as 74.8 ± 3.7% and confirmed as 76.4 ± 0.6%. Compared with the normal operating conditions at the plant, the optimization resulted in more than 12% and 27% improvement in the yeast activity and viability, respectively.     

Cr(VI) removal by continuous electrodeionization: Study of its basic technologies

The capabilities of continuous electrodeionization process (CEDI) and its basic technologies (electrodialysis (ED) and ion exchange (IX)) were analyzed in order to remove hexavalent chromium from synthetic solutions at pH 5. A cell with two chambers (dilute and concentrate) was used. Two cation exchange membranes (CM-1) and one anion exchange membrane (AFN) (40 cm² effective area) were employed in the experimental setup. IX technology was single evaluated using an IRA-67 anionic resin to know its independent performance from the other technologies, whereas ED was studied in the cell; I_lim determination was done by I vs. U plots and factors of 0.7 I_lim and 0.85 I_lim were applied to ED process. Finally, EDI process was studied at the same conditions that ED in order to know the resin bed role. During IX the removal reached was 50%; ED 98% after 6.25 h operation with an energy consumption of 1.21 kW h/m³; EDI (anionic bed) accomplishing 97.55% chromium removal (energy consumption of 0.91 kW h/m³). Finally EDI with mixed bed removed 99.8% in 1.3 h and of 0.167 kW h/m³ of energy consumption.     

Temperature and catalyst effects on the production of amorphous carbon nanotubes by a modified arc discharge

Large amounts of amorphous carbon nanotubes (ACNTs) were prepared with Co-Ni alloy powders as catalyst in hydrogen gas atmosphere by a modified arc discharging furnace which can control temperature during the electric arcing process. The experimental results indicate that the cooperative function of temperature and catalyst plays an important role in the soot production rate and the relative ACNT purity. When temperature increases from 25 °C to 700 °C, the soot production rate increases from around 1 g/h to 8 g/h, the best relative ACNT purity at 600 °C can reach up to 99% compared to the room temperature sample. Without catalyst, only plate graphite is formed at 25 °C and very few carbon nanotubes are found when temperature increases to 600 °C. TEM, SEM, HRTEM and XRD analysis showed that the as-prepared carbon nanotubes are almost amorphous. The soot production rate is 8 g/h and diameter range of amorphous carbon nanotubes is about 7-20 nm, respectively.     

Design of process parameters for the production of xylose from wood sawdust

Meranti wood sawdust (MWS) is a cheap and widely available lignocellulosic biomass, which can be a potential source of xylose. This xylose can be an economic raw material for the production of a wide variety of specialty chemicals, mainly xylitol. It is particularly important to establish rapid hydrolysis conditions, which can yield xylose-rich hydrolysate that do not require further treatment. The aim of this research was to study the effect of residence time, temperature, acid concentration, and liquid to solid ratio (LSR) on the formation of xylose and byproducts. Batch hydrolysis was performed using different levels of residence time (10–120 min), temperature (105–130 °C), H₂SO₄ concentration (2–12%), and LSR (8–20 g/g). One-factor-at-a-time (OFAT) method was followed to select the optimum level of parameters. The residence time, temperature, and acid concentration were found to be the major factors affecting xylose production with the effective level of 60 min, 125 °C, and 4%, respectively. In these conditions, the xylose concentration was 17.9 g/l, corresponding to a yield of above 86% of the potential concentration.     

Flaming pyrolysis model of the fixed bed cross draft long-stick wood gasifier

The future industrial development of biomass energy depends on the application of renewable energy technology in an efficient manner. Of all the competing technologies under biomass, gasifiers are considered to be one of most viable applications. The use of biomass fuel, especially biomass wastes, for distributed power production can be economically viable in many parts of the world through gasification of biomass. Since biomass, is a clean and renewable fuel, gasification gives the opportunity to convert biomass into clean fuel gas or synthesis gas for industrial uses. The preparation of feedstock for a gasifier requires time, energy and labour and this has been a setback for gasifier technology development. The present work is focused on gasification of long-stick wood as a feed material for gasifiers. This application makes reduction not only in the cost but also on the power consumption of feed material preparation. A 50 m³/h capacity gasifier was fabricated in the cross draft mode. The cross draft mode makes it possible to produce low tar content in producer gas. This cross draft mode operates with 180 W of blower supply for air to produce 10 kW of thermal output. The initial bed heights of the long-stick wood and charcoal are 58 cm and 48 cm respectively. Results were obtained for various flow conditions with air flow rates ranging from 20 to 30 m³/h. For modelling, the flaming pyrolysis time for long-stick wood in the gasifier is calculated to be 1.6 min. The length of the flaming pyrolysis zone and char gasification zone is found to be 34 cm and 30 cm respectively. The rate of feed was between 9 and 10 kg/h. Continuous operation for 5 h was used for three runs to study the performance. In this study we measured the temperature and pressure in the different zones as a function of airflow. We measured the gas flow and efficiency of the gasifier in order to determine its commercial potential for process and power industries.     

Polyaniline/single-wall carbon nanotube (PANI/SWCNT) composites for high performance supercapacitors

PANI/SWCNT composites were prepared by electrochemical polymerisation of polyaniline onto SWCNTs and their capacitive performance was evaluated by means of cyclic voltammetry and charge-discharge cycling in 1 M H₂SO₄ electrolyte. The PANI/SWCNT composites single electrode showed much higher specific capacitance, specific energy and specific power than pure PANI and SWCNTs. The highest specific capacitance, specific power and specific energy values of 485 F/g, 228 W h/kg and 2250 W/kg were observed for 73 wt.% PANI deposited onto SWCNTs. PANI/SWCNT composites also showed long cyclic stability. Based upon the variations in the surface morphologies and specific capacitance of the composite, a mechanism is proposed to explain enhancement in the capacitive characteristics. The PANI/SWCNT composites have demonstrated the potential as excellent electrode materials for application in high performance supercapacitors.     

Pelletised fuel production from palm kernel cake

Biomass is an important source of renewable energy. Worldwide, the palm oil industry generates large amounts of waste materials, such as shells, fibres and palm kernel cake, which can be used for power generation. Processing the palm kernel cake into a uniform fuel through pelletisation will be an attractive option — assessing the suitability of this process was the main objective of this research. Extensive analytical and pelletisation tests were performed to evaluate the physical properties of pellets produced from this material. The variables explored included the pelletisation pressure, temperature, fuel moisture and the effect of binders, which all had significant effects on density and tensile strength. The most favourable conditions for pellet production were a pressure of 9338 psi/64.38 MPa, a temperature of 80-100 °C and a fuel moisture content of 7.9%. These pellets had densities of 1184-1226 kg/m³ and tensile strengths of 930-1007 kPa. Adding small amounts of caustic soda (1.5-2.0wt%) to the palm kernel cake under these conditions increased the tensile strength to 3055 kPa, whereas starch additives were not found to be effective binders. It is estimated that the production of palm kernel cake pellets with 2 wt.% of the caustic soda binder would cost approximately £28-47/tonne.     

Decolorization and COD reduction of disperse and reactive dyes wastewater using chemical-coagulation followed by sequential batch reactor (SBR) process

This paper summarizes the results of disperse and reactive dyes wastewater treatment processes aiming at the destruction of the wastewater's color and chemical oxygen demand (COD) reduction by means of coagulation/flocculation (CF) followed by sequential batch reactor (SBR) process. The color removal efficiency of magnesium chloride aided with lime [MgCl₂/CaO] was compared with that of alum [Al₂ (SO₄)₃] and lime [Cao]. The experimental results showed that treatment with lime alone (600 mg/l) at pH value of 11.7 proved to be very effective. Color removal reached 100% and COD was reduced by 50%. Treatment with magnesium chloride aided with lime at pH value of 11 removed color completely and reduced the COD value by 40%. However, lime or lime in combination with magnesium chloride produced high amounts of sludge (1.84 kg/m³ for lime & 1.71 kg/m³ for MgCl₂ aided with lime). Also, the pH of the treated effluent was around 11 and needs correction prior to discharge into sewer network. The use of 200 mg/l alum without pH adjustment removed 78.9% of the color. To improve the effectiveness of alum, the cationic polymer namely cytec was used as a coagulant aid. This significantly increased color removal from 78.9 up to 94% and COD reduction was around 44%. Moreover, sludge production was only 0.36 kg/m³. Chemically pre-treated effluent was subjected to SBR process at an HRT of 5.0 h. Residual COD_total, total biochemical oxygen demand (BOD_{5 total}) and total suspended solids (TSS) in the final effluent were 78 ± 7.7; 28 ± 4.2 and 17 ± 4.2 mg/l, corresponding to the removal efficiency of 68.2; 76.3 and 61.4% respectively. Furthermore, almost complete removal of COD_particulate and BOD_5particulate has been achieved.     

Bioethanol production from corn meal by simultaneous enzymatic saccharification and fermentation with immobilized cells of Saccharomyces cerevisiae var. ellipsoideus

The simultaneous enzymatic saccharification and fermentation (SSF) of corn meal using immobilized cells of Saccharomycescerevisiae var. ellipsoideus yeast in a batch system was studied. The yeast cells were immobilized in Ca-alginate by electrostatic droplet generation method. The process kinetics was assessed and determined and the effect of addition of various yeast activators (mineral salts: ZnSO₄ · 7H₂O and MgSO₄ · 7H₂O, and vitamins: Ca-pantothenate, biotin and myo-inositol) separately or mixed, was investigated. Taking into account high values of process parameters (such as ethanol concentration, ethanol yield, percentage of the theoretical ethanol yield, volumetric productivity and utilized glucose) and significant energy savings the SSF process was found to be superior compared to the SHF process. Further improvement in ethanol production was accomplished with the addition of mineral salts as yeast activators which contributed to the highest increase in ethanol production. In this case, the ethanol concentration of 10.23% (w/w), percentage of the theoretical ethanol yield of 98.08%, the ethanol yield of 0.55 g/g and the volumetric productivity of 2.13 g/l·h were obtained.     

Experimental, kinetic and 2-D reactor modeling for simulation of the production of hydrogen by the catalytic reforming of concentrated crude ethanol (CRCCE) over a Ni-based commercial catalyst in a packed-bed tubular reactor

Mechanistic kinetic models were formulated based on Langmuir-Hinshelwood-Hougen-Watson and Eley-Rideal approaches to describe the kinetics of hydrogen production by the catalytic reforming of concentrated crude ethanol over a Ni-based commercial catalyst at atmospheric pressure, temperature range of 673-863 K, ratio of weight of catalyst to the molar rate of crude ethanol 3472-34722 kg cat s/kmol crude in a stainless steel packed bed tubular microreactor. One of the models yielded an excellent degree of correlation, and was selected for the simulation of the reforming process which used a pseudo-homogeneous numerical model consisting of coupled material and energy balance equations with reaction. The model was solved using finite elements method without neglecting the axial dispersion term. The crude ethanol conversion predicted by the model was in good agreement with the experimental data (AAD%=4.28). Also, the predicted concentration and temperature profiles for the process in the radial direction indicate that the assumption of plug flow isothermal behavior is justified within certain reactor configurations. However, the axial dispersion term still contributed to the results, and thus, cannot be neglected.     

A direct electrochemical route from oxide precursors to the terbium-nickel intermetallic compound TbNi5

Successful direct electrochemical reduction of mixed powders of terbium oxide (Tb₄O₇) and nickel oxide (NiO) to the intermetallic compound, TbNi₅, is demonstrated in molten CaCl₂ at 850 °C by constant voltage (2.4-3.2 V) electrolysis. The reduction mechanism was investigated by cyclic voltammetry using a molybdenum cavity electrode in conjunction with characterisations of the products from both constant voltage and potentiostatic electrolysis under different conditions by XRD, SEM and EDX. It was found that the reduction started from NiO to Ni, followed by that of Tb₂O₃ (resulting from Tb₄O₇ decomposition) on the pre-formed Ni to form the intermetallic compound. The reduction speed increased with increasing the cell voltage, but the speed gain was counterbalanced by decreased current efficiency and increased electric energy consumption. At 2.4 V, the current efficiency reached 63.2%, and the energy consumption by electrolysis was as low as 3.2 kWh/kg TbNi₅ when the oxide phase was converted fully to the metal phase (XRD) in 4 h. The oxygen level in the produced TbNi₅ could readily reach 1800 ppm by electrolysis at 3.2 V for 12 h with the energy consumption being 18.9 kWh/kg TbNi₅.