The effect of O2 enrichment on NOx formation in biomass co-fired pulverised coal combustion

Oxygen enrichment of the combustion air in pulverised coal combustion for power plant is seen as a possible retrofit measure to improve CO₂ scrubbing and capture. This technique produces a reduced volume of flue gas with higher CO₂ concentration than normal air combustion that will contributes to the enhancement of amine scrubbing plant efficiencies. We report in this article the results of a study at the small pilot scale into the effect of these combustion modifications on the formation of NO_x and associated carbon burnout changes. Experiments were performed using a Russian coal, typical of that used in some UK power stations with shea meal and Pakistani cotton stalk as biomass fuels co-fired at a fraction of 15%th. The down-fired pulverised coal combustor was operated at 20 kWth under air-staged conditions for NO_x control and the secondary and over-fire air flows were both enriched by up to 79% (100% O₂) for a range of splits giving a 35% overall O₂ concentration for full enrichment. When the same enrichment process was applied to biomass/coal combustion different behaviour was observed with respect to NO_x formation. We have shown that oxygen enrichment can achieve benefits of improved carbon burnout with a positive impact on NO_x emissions over and above the primary aim of increasing CO₂ concentration in the flue gas for enhanced capture efficiencies. With all other conditions of overall stoichiometry, OFA levels and O₂ enrichment levels remaining the same, NO_x levels at 22% OFA initially increased over the range of secondary air enrichment, particularly for shea meal/coal co-firing. At 31% OFA the trends were to lower NO_x at high enrichment levels. However, co-firing with shea meal initially showed an increase in NO_x emission at lower levels of enrichment (up to 40% O₂) followed by overall lower NOx emissions at 100% O₂ in the secondary air. The results show that NO_x emissions can either increase or decrease depending on the operating conditions. The differences in behaviour are attributed, not only to the effects of enrichment on the stoichiometry of the near-burner zone, but also on the flame dynamics and intensity of combustion related to the associated reductions in gas velocity and swirl intensity by the transition from air to pure O₂ in the secondary oxidant stream.     

Devolatilization of wood and wastes in fluidized bed

Experiments were carried out in a laboratory fluidized bed (FB) to characterize the devolatilization behavior of wood and various wastes at temperatures applicable to FB gasification and combustion, i.e. 750-900 °C. The fuels tested were pellets made of wood, meat and bone meal, and compost (from municipal solid wastes), as well as dried granulates of sewage sludge (DSS). Determination of yields of char, condensate and light gas, as well as the composition of the gas and the time of devolatilization during the pyrolysis of single fuel batches was made. A simple model was developed to analyze the mode of conversion of a single wood pellet and DSS granulate, giving insight on the controlling mechanisms during devolatilization. The devolatilization kinetics of DSS was determined by tests using fine granulates. The model was successfully applied to simulate the conversion of large DSS granulates and wood pellets under the whole range of temperatures analyzed.     

提高快速滴定法测定生料中氧化钙准确度的措施

酸溶EDTA滴定法能快速测定生料中的氧化钙含量,在生产管理中可用作荧光分析测定结果的复检手段,但关键是要确保其检测的精密度和准确度。通过控制检测过程中的称量精度(采用高精度天平)和称量质量(取0.1000g),溶样时加热至沸并保持微沸2min以保证足够的溶样时间;同时EDTA标准溶液消耗量取较高量(取35ml),且CMP指示剂中的三种原料钙黄绿素、甲基百里香酚蓝、酚酞的质量配比按±0.2,±0.2和±0.1幅度变化,……就可达到绝对误差在0.10%左右、较碱熔法略低0.06%的准确测定结果。     

超声波法提取紫苏中迷迭香酸条件的研究

用超声波法从紫苏中提取迷迭香酸,通过正交实验确定最佳提取工艺和最大影响因素,结果表明:超声波法提取迷迭香酸的最佳提取工艺为:提取时间40min,乙醇浓度60%,料液质量体积比1:20,提取温度60℃,低频率超声波(25～28kHz);该方法中提取温度对得率的影响最显著。     

Optimization of Enzymatic Production of Oligopeptides from Apricot Almonds Meal with Neutrase and N120P

Neutrase 0.8L and N120P proteases were used for oligopeptide production from apricot almonds meal, and response surface design was carried out to optimize the effect of hydrolysis conditions on hydrolysis degree (DH) and oligopeptide yield rate. Four independent variables were used to optimize the hydrolysis process: hydrolysis temperature (X(1)), enzyme-to substrate ratio (E/S) (X(2)), substrate concentration (X(3)) and reaction time (X(4)). Statistical analysis indicated that the four variables, quadratic terms of X(1), X(3), and X(4), and the interaction terms with X(1) had a significant (p < 0.05) effect on DH. The yield rate was also significantly affected by the four variables and quadratic terms of X(1), X(2) and X(4). Two mathematical models with high determination coefficient were obtained and could be employed to optimize protein hydrolysis. The optimal hydrolysis conditions were determined as follows: hydrolysis temperature 52.5 °C; enzyme-to-substrate ratio (E/S) 7200 U/g; substrate concentration 2%; reaction time 173 min. The initial pH 6.5 and Neutrase-to-N120P dosage ratio 2:1 were fixed in this study according to the preliminary research. Under these conditions, the experimental DH and yield rate were 34.10 ± 5.25% and 72.42 ± 2.27%, respectively.     

Sensory evaluation of a hard white compared to a hard red winter wheat

Traditionally bread wheats grown in the USA have been hard red genotypes. Introduction of hard white genotypes provides an opportunity for the comparison of the products and evaluation of consumer acceptance. MT 7811, a hard white wheat, and ‘Norwin’, a hard red winter wheat, were grown in adjacent plots in each of two years. Grain from each was divided, with half milled into whole wheat flour (wholemeal) and the other half milled into white flour (milled flour). Breads made from wholemeal and milled flour from each wheat genotype were tested by panelists for differences. Color differences were easily detected. The Wilcoxon-Mann Whitney rank sums test was used to evaluate signal detection data. Both crust and crumb differences between the two wheats could be detected by some panelists. Differences could be detected between the two wheat types in either wholemeal or milled flour bread. Crust differences were often greater than crumb differences. Trained panelists commented on some bitterness in red wheat products and a sweetness in white wheat products.     

利用有腺体棉籽粕生产食用棉仁分离蛋白的实践

棉仁蛋白是一种潜在的重要食品资源,由于棉酚的存在一直未被人类充分利用。通过甲醇脱酚、4#溶剂脱脂、低温连续脱溶的棉籽粕生产工艺和碱溶酸沉的蛋白生产工艺,于2001年首次实现了工业化利用有腺体棉籽粕生产食用棉仁分离蛋白的实践,获得了高安全性的棉仁分离蛋白。     

大豆低温脱溶粕中两种异黄酮单体分离与结构鉴定

以大孔树脂柱色谱、制备薄层色谱从大豆粕乙醇提取物中分离出二种异黄酮单体,经HPLC,UV,IR,ESI／MS,和1H NMR,13C NMR,DEPT NMR,HQSC NMR分析确证其结构是大豆甙(daidzin)和染料木素(genistein)。     

用HPLC测定酶解玉米蛋白氨基酸的组成

利用高效液相色谱对玉米黄粉蛋白的酶解产物进行氨基酸组成测定，发现酶解产物中含有大量的Pro和Phe、Leu等必需氨基酸，因此可以用作保健食品来补充必须氨基酸和降低高血压患者的血压，具有广阔的应用前景。     

两级双液相萃取棉籽联产生物柴油和无毒棉粕

采用两级双液相萃取棉籽联产生物柴油和无毒棉粕。与一步双液相萃取法处理棉籽技术相比,该法在保持甲醇总量不变的基础上,将双液相萃取分为两级进行,二级萃取用的甲醇在完成了萃取功能以后再作为酯交换反应原料使用,不再需要重新加入新鲜的甲醇进行反应,减少了甲醇用量和溶剂再生的负荷。得出酯交换反应的最佳条件为:一级萃取甲醇用量为甲醇总量的60%,催化剂用量为棉籽油质量的1.1%,反应温度60℃,反应时间120 min。在最佳反应条件下,生物柴油产物中脂肪酸甲酯含量可达98.8%;萃取棉粕中游离棉酚含量为0.013%,符合美国国家棉籽产品协会的贸易标准,可用作动物饲料等。