Modeling calcium and water intake in threshed corn grain during thermo-alkaline treatment

A mathematical model describing simultaneous solvent diffusion and gelatinization of starch was used to explain the water and calcium absorption in threshed corn grains during the thermo-alkaline treatment. A computer-aided nonlinear optimization technique was used to find the effective diffusion coefficients and the reaction rate constants of water and calcium in threshed corn grains at boiling temperature (92.5 ± 0.3 °C). The mathematical model shows good correlation between measured and predicted values of water and calcium intake. It is concluded that the cooking process is limited by the reaction of starch components with water and calcium. The effective diffusion coefficient for water varied between 1.18 × 10⁻¹⁰ and 1.45 × 10⁻¹⁰ m²/s and for calcium between 8.55 × 10⁻¹⁰and 16.77 × 10⁻¹⁰ m²/s. The diffusion of water and calcium in threshed corn was produced with a reaction rate constants in the range of 6.83 × 10⁻⁴ to 10.4 × 10⁻⁴ s⁻¹ for water and 2.7 × 10⁻⁵–7.6 × 10⁻⁵ s⁻¹ for calcium. According to these effective diffusion coefficient values the diffusive process seems to be slower for water than for calcium. However, the reaction rate constant values are approximately 10 times higher for water than for calcium which may indicate that a higher amount of solvent was linked in the water diffusion process due to the gelatinization. Low concentration of Ca(OH)₂ such as 0.10% did not significantly affect the water diffusion of threshed corn during the cooking process.     

The efficient lignocellulose-based sorbent for oil spill treatment from polyurethane and agricultural residue of Vietnam

In this study, new and efficient sorbent with density 0.2 g/cm³ was fabricated by incorporating rice straw into polyurethane matrix to get an open cell structure material with high oil uptake capacity. The influences of various important factors such as amount of adding rice straw, size of rice straw particles, and adsorption time on oil adsorption capacity of new sorbent material were investigated. The results showed that the oil absorption rate occurred fast in first 15–30 min, then slowed down and reached saturation level after about 2 h of treatment. Oil adsorption capacity of the new sorbent material was relatively high, up to 12.0 g/g. In comparison with pristine polyurethane or lignocellulosic materials, the new sorbents had higher oil adsorption capacity. Some characteristics of the as-obtained sorbent, such as surface shapes and porosity, were also studied by SEM analysis.     

秸秆饰面墙体砌砖成型机的设计及其应用分析

阐述了秸秆饰面墙体砌砖成型机的设计方案,具体包括基本结构及工作原理。为满足秸秆墙体砌砖在建筑用材上较高强度和密实度的要求,关键对于成型装置和进料装置进行了设计和装配,使一次挤压中得以实现二次进料以及隔层中玻纤维添加的连续过程。并将秸秆饰面墙体砌砖在主要性能指标上与水泥砖进行对比分析,剖析秸秆墙体砌砖的优势和竞争力,而且通过经济指标上具体产值和节能效益的计算,分析得出该设备及其产品较大的市场价值和发展前景。     

Evaluation of a hydrothermal process for pretreatment of wheat straw—effect of particle size and process conditions

BACKGROUND: Hydrothermal processes are an eco‐friendly processes that provide an interesting alternative for chemical utilization of lignocellulosic materials, in which water and crop residues are the only reagents. In this work the effect of process conditions (size distribution of the wheat straw, temperature and time) was evaluated against production of fermentable products. RESULTS: The use of milled wheat straw fractions as a raw material containing blends of different particle size distribution showed that the latter had an influence on the final sugars in the hydrolysate. Improved values of glucose (21.1%) and xylose yields (49.32%) present in the hydrolysate were obtained with treatment severity factors of 2.77 and 3.36, respectively. Mathematical models were developed aimed at establishing the effect of process conditions on monosaccharide concentration and its degradation in the liquor. CONCLUSION: This work shows that the use of wheat straw blends with various particle sizes has a significant effect on the extraction of fermentable products. The effect of treatment severity, which takes into account both processing time and temperature was also evaluated. These results are of importance for process design. Copyright © 2010 Society of Chemical Industry     

燃煤－秸秆压块层燃混烧试验研究

在一台蒸发量为10t／h的链条炉排炉上进行了燃煤一秸秆压块的混烧试验,混烧秸秆压块可有效改善燃煤的着火特性,显著提高燃烧效率。与纯粹燃煤相比较,混烧质量比20％－30％的生物质压块可使锅炉的热效率提高3％左右。     

建筑用绝热金属面夹芯板抗弯承载力的试验研究

金属面夹芯板是很常用的建筑保温隔热材料。目前,最新夹芯板国家规范仅包括岩棉和聚氨酯的承载力设计公式,对其他面夹芯板没有涉及。通过对48个不锈钢、铝板、秸秆面夹芯板抗弯试验和27个材料性能试验,得到各种芯材的基本材料性能以及不同夹芯板的抗弯承载力,为统一抗弯承载力公式的推导打下基础。     

混凝土夹芯秸秆块砌块传热特性及优化措施

采用数值计算的方法对混凝土夹芯秸秆块砌块的传热进行模拟,得出砌块的稳态温度场、热流密度场等,计算出平均传热系数;与测试结果进行比较,得出模拟值与试验值相差仅为5.6％;根据模拟结果,认为砌块肋部热桥是影响保温性能的重要因素,并提出提高砌块保温性能的具体方案和措施.     

两种不同包膜材料控释肥料在玉米上的增产效果

采用田间试验研究了硫黄加树脂包膜尿素(SPCU)、树脂包膜尿素(PCU)在玉米上的施用效果。结果表明:氮素同等用量时控释尿素增产效果显著,分别比相对应的等氮量普通尿素(PU100%)增产7.3%、5.9%,N用量减少30%的SPCU70%、PCU70%处理产量分别比相对应的等氮量普通尿素(PU70%处理)增产10.2%、9.1%;控释尿素氮素用量比普通尿素氮素用量减少30%,不影响夏玉米产量。     

秸秆/淀粉发泡材料的制备与表征

以秸秆为原料,加入玉米淀粉、甘油、胶黏剂、填充剂和交联剂后烘焙发泡,制得复合发泡体。分析发泡体的密度、力学性能以及自降解性能,通过Design Expert Version 7.0.0软件对实验进行中心组合设计。结果显示：NaOH浓度、淀粉、胶黏剂和交联剂添加量对发泡体密度的交互影响显著;发泡体为黄褐色,表面光洁,气孔均密;单因素实验显示反应时间为10~14小时,反应温度为65~67℃;降解性能可能与淀粉添加量和周围环境有关。