氨蒸馏塔液位测量系统的改造

介绍了用内装电容式液位检测计测量氨蒸馏塔液位的方法。该法安装简便、检测准确。     

Influence of nitrogen nutrition and metabolism on ammonia volatilization in plants

Barley (Hordeum vulgare L. cv. Golf) was grown in solution culture with controlled nitrogen availability in order to study the influence of nitrogen nutrition on ammonia emission from the leaves. Ammonia emission measured in cuvettes connected to an automatic NH₃ monitor was close to zero for nitrate grown plants but increased to 0.9–1.3 nmol NH₃ m^-2 leaf area s^-1 after 3–5 days of ammonium nutrition. Increasing concentrations from 0.5 to 10 mM NH₄ ⁺ in the root medium increased NH₃ emission from the shoots, root glutamine synthetase activity and NH₄ ⁺ concentrations in apoplast, xylem sap and bulk tissue, while apoplastic pH values decreased.Inhibition of glutamine synthetase in nitrate grown barley plants by addition of 1 mM methionine sulfoximine (MSO) to the root medium caused ammonia emission to increase 5 to 10-fold after 2–3 hours. At the same time shoot tissue ammonium concentrations started to increase. Addition of an inhibitor of photorespiration, 1 mM pyrid-2-yl hydroxymethane sulfonate (HPMS) reduced this increase in ammonia emission showing a relation between NH₃ emission and photorespiration.Oil seed rape (Brassica napus L. cv. Global) plants grown at 3 different nitogen levels (2N, 4N and 7N) in a sand/soil mixture showed increasing NH₃ compensation points with increasing N level. This increase was highly correlated with increasing NH₄ ⁺ concentrations in the leaf apoplast and total leaf tissue. The NH₃ compensation points could be succesfully predicted on basis of the pH and NH₄ ⁺ concentration in the leaf apoplast.     

国产设备在氨汽提尿素工厂中的应用

介绍了氨汽提生产尿素的工艺特点,以及在４００ｔ／ｄ尿素装置中采用国产设备的使用情况与存在问题,为今后新建同类装置提供了经验。     

Browning susceptibility of minimally processed Baby and Romaine lettuces

 This study was conducted to determine the effects of cultivar, tissue susceptibility and storage temperature on the keeping quality of minimally processed Baby and Romaine lettuces. Midrib and photosynthetic tissues were lightly processed and stored for up to 7 days at 5  °C and 13  °C. Changes in L ^* and a ^* values and absorbance at 430 nm were compared. The relationship between polyphenols, phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) activities and browning was examined. Measurements of L ^* and a ^* values on midribs showed that browning discoloration was the same for Baby as for Romaine lettuces and there was no relationship for temperature. In addition, L ^* and a ^* values in photosynthetic tissue indicated a decrease in green pigmentation during storage, especially at 13  °C. For both kinds of tissue at the end of cold storage an increase in soluble brown polymers was detected. In midribs, total phenolics increased significantly throughout the storage period because of the tissue-wounding response. The photosynthetic tissue had a higher phenolic content than the midrib one. For both kinds of tissue an increase in PPO activity occurred throughout cold storage. On the other hand, PAL activity in midrib tissue only increased initially, followed by a slow decline to reach normal levels. Browning potential estimated by L ^* values correlated significantly (P>95%) with PPO activity and with absorbance at 430 nm for Romaine lettuce. Based on colour and browning potential no differences between Romaine and Baby lettuce cultivars were observed. However, photosynthetic tissue was the most suitable tissue for the preparation of minimally processed salad mixes because of its high phenolic content. Received: 28 September 1998     

基于MATLAB的四段冷激式氨合成塔模拟与操作优化

采用一维拟均相数学模型,模拟计算了国内具有代表性的日产千吨的Kellogg氨合成塔操作工况,在此基础上运用MATLAB语言对该塔的操作工况进行优化。结果表明,通过对现有塔操作条件的优化,可以达到提高产量的目的。     

A202、A110-1型催化剂在氨合成塔的升温还原

介绍了一轴三径氨合成塔内件的结构和流程,叙述了A202、A110—1型催化剂在该塔的装填情况、升温还原方案和升温还原历程。对升温还原的经验和教训进行了总结。生产实践表明,氨合成塔进、出口氨的体积分数分别为2．87％和13．7％,合成氨日产量达到362t。     

全低变工艺在甲醇生产中的应用

介绍了变换系统采用的全低变工艺流程、升温硫化流程和控制指标,总结了全低变装置的实际运行效果和操作要领。     

三套管氨合成塔中催化剂活性系数的快速确定

根据氨合成塔生产过程中若干个工艺灵敏参数之间的关系,建立了催化剂活性系数的分布和变化模型。采用数学模拟计算值与生产实测参数相对照的方法,简单快速地确定催化剂在不同使用时期的活性系数。     

氨-硫铵法在锅炉烟气脱硫中的应用

介绍了氨-硫铵法锅炉烟气脱硫的原理和工艺流程,论述了该生产技术的要领和工艺指标的控制方法,结合生产运行实例,分析了脱硫装置的经济技术指标、副产品硫酸铵的质量及其市场销售情况,结果表明,脱硫效率可达95％以上。     

氨合成塔的优化设计

通过数学模拟计算,定量地分析和讨论了三套管氨合成塔在一定的设计压力、热点温度和氢氮比条件下,催化床进口氨含量、惰气含量、温度、空速和催化荆活性系数对氨合成反应的影响以及这些因素之间的内在关系,提出了在最优调节参数下实现氨合成塔优化操作和确定较适宜工艺设计参数的理论依据和方法。结果表明,催化床进口温度是实现氨合成塔优化操作的最优调节参数。