过氧化氢生产中氧化收率偏低的后果及解决

我公司现有黎明设计院设计1990年投产的千吨级和天津设计院设计1995年投产的万吨级过氧化氢生产装置各1套，采用的是蒽醌法生产工艺，由氢化、氧化、萃取、净化、后处理5道工序组成，目前的产能是年产浓度27．5％的双氧水27kt。多年来，2套装置总体运行稳定，但也出现过一些异常，险些酿成生产事故，氧化收率明显偏低即是问题之一。

过氧化氢装置氧化工序氢化液氧化收率的提高

摘要针对过氧化氢装置的氧化工序氧化收率偏低的问题，以气液反应双膜理论为基础．提出了强化氧化反应作为重点研究方向．围绕氧化塔优化了氧化工序的设计，同时研究了氧化工序的各项工艺指标（塔温、塔压、尾气氧含量、氢化液pH等）操作控制对氧化收率的影响。结果表明，氧化塔的反应温度控制在40—56℃、氧化尾气压力控制在220～240kPa、氧化尾气氧的质量分数控制在4．0％．5．0％、氢化液oH控制在4．5～5．5比较合理。通过优化氧化工艺设备和工艺指标，其氧化收率日均由88％提高至95．8％-96．5％。

过氧化氢生产中氧化收率低的原因及解决措施

氧化反应是在氧化塔内进行，氧化塔分上下两节，每节底部有不锈钢多孔空气分散器，塔外有冷却夹套，空气与加了磷酸的氢化液一同进入上塔，反应完后再进入下塔，其反应流程见图1。

过氧化氢生产中氧化工序的优化

国内双氧水生产中普遍存在氢化效率高 ,氧化效率偏低 ,导致氧化收率较低的问题。探讨了问题产生的原因 ,介绍了对氧化工序的优化。

醇用DMSO-氯化磷腈温和而有效氧化

DMSO加入-40℃氯化磷腈的二氯甲烷溶液中，然后再加醇（伯醇、仲醇、烯丙基醇和苄醇）和Et3N，同温搅拌反应45min后室温反应8h，得相应的酮或醛。含硫原子的醇、香叶醇氧化收率均佳。硅醚和四氢吡喃醚基团在反应中稳定。21例收率57％～97％。

乙醛酸法合成4-羟基-3-甲氧基苯甲醛和4-羟基-3-乙氧基苯甲醛的氧化催化剂

本发明涉及乙醛酸法合成4-羟基-3-甲氧基苯甲醛和4-羟基-3-乙氧基苯甲醛的氧化催化剂，用以表述构成该催化剂组合物的元素及其摩尔含量的组成式为：Mg0-0.3·Mo0-0.02·Fe0.03-0.3·Cu0.004-0.04·Zn0.002-0.07·Al0-0.7·K0.009-0.4·Na0-0.03·O0.1-3.0·S0.05-0.9，其制备方法为：取需要量的氧化铝或／和氧化铁为原料（Ⅰ）；分别取需要量钼元素的钠盐、需要量的其他金属元素的硫酸盐为原料（Ⅱ）；将二者混匀球磨lh得到所需催化剂。二产品氧化收率均高于Na型催化剂。每批过滤4t物料节省220min，清网次数为Na型1／4次。

板板式介质阻挡放电等离子体直接合成过氧化氢研究

本文采用自行设计的板板式介质阻挡放电(DBD)反应器,在常温常压条件下转化氢氧混合气体直接合成过氧化氢。系统考察了介质种类,介质厚度及气隙间距对氧气转化率、过氧化氢选择性、收率及能量效率的影响。发现石英是合成过氧化氢反应器的适宜介质,介质厚度及气隙间距对合成过氧化氢的收率及能量效率有显著影响。当介质厚度与气隙间距均为2.0mm,注入功率为9.1W时,过氧化氢收率及能量效率分别达到20.6%和5.5gH2O2/kWh。

3500t/a双氧水装置填料塔氧化改空塔氧化

介绍了3500t/a双氧水装置氧化工序的生产工艺,改造前和改造后氧化塔的结构特点、改造过程、技术参数、改造后的运行情况。

苯氧化制顺酐催化剂

氧化收率≥90％，转化率〉99％，酸水质量好，由于熔盐浴温度较低，且活性组份附着性好，因而催化剂寿命长。本催化剂制造成本仅是国内催化剂售价的30％（载体自制）。根据国外经验大型的顺酐生产厂家具有自己催化剂研发力量，且可外卖。在催化剂负荷上本人不主张苯浓度过高，而是通过提高空速予以解决，因为这样安全。接受技术服务的厂家不仅有可观经济效益，还可培养一批顺酐催化剂研发人员。

3,5-二羟基苯甲醛的斯文氧化合成

以3,5-二羟基苯甲醇为原料,利用斯文氧化反应氧化羟甲基制备3,5-二羟基苯甲醛,收率83.1%并对氧化剂用量、滴加速度、反应介质及用量、萃取剂进行了优化。

混合消毒剂发生器运行条件对ClO_2收率的影响

以二氧化氯与氯混合消毒剂发生器为研究对象,分析了反应温度、计量泵频率、原料投加比以及母液循环装置对二氧化氯收率的影响。研究表明,发生器最佳的反应温度为65℃,最适进料比为V(31%的HCl)∶V(27%的NaClO3)=1.2∶1,运行时计量泵频率不应大于30 Hz,增加母液循环可以增大发生器收率,降低并稳定氯酸盐的带入量。

双氧水装置扩产可行性探讨

1989年12月河北沧州大化集团有限责任公司(简称沧州大化)建成投产了3500t/a 27.5%的镍催化剂双氧水装置,该装置年生产日300d,工作液循环量14～15m3/h,氢化效率设计值9.5～10g/L,氧化收率设计值95%(氧化收率=氧化效率/氢化效率),开车运行至今.

蒽醌法生产双氧水降酸耗措施

针对双氧水生产系统消耗酸过多 ,导致氧化收率低、残液量大等问题 ,提出增加流速 ,用流量计调节酸量等措施 ,取得了显著效果 ,为同类双氧水厂家降酸耗提供了很好的依据。

Improved recovery of a low-grade refractory gold ore using flotation–preoxidation–cyanidation methods

In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60 min of flotation at the grind size with K80 of 146 micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.

Absorption Rate of CO_2 into MDEA Aqueous Solution Blended with Piperazine and Diethanolanline

Absorption rate of CO2 into aqueous solution of N-methyldiethanolamine (MDEA) blended with diethanolamine (DEA) and piperazine (PZ) was studied and a kinetic model was established. It is shown that homogeneous activation mechanism could explain this absorption process. The absorption rate coefficients of carbon dioxide into MDEA aqueous solution blended with DEA, PZ or DEA+PZ were compared with each other. The results demonstrated that the different activation effect of DEA, PZ and DEA+PZ on the carbon dioxide absorption comes from the difference in CO2 combination rate, transport of PZ and DEA to MDEA and the regeneration rate of PZ and DEA.

Potassium superoxide oxygen generation rate and carbon dioxide absorption rate in coal mine refuge chambers

The effects of the molding pressure of a KO2 oxygen plate and the initial concentration of CO2 on the oxygen generation rate, the oxygen generation efficiency, and the carbon dioxide absorption rate were studied using a YES-300 hydraulic press to alter the pressure when forming the oxygen plate used in a coal mine refuge chamber. In addition, changes in the initial concentration of CO2 used in the closed- box model were made by adjusting the CO2 supply system, and a CD-7 multi-function parameter instrument was employed to monitor and record the changes of O2 and CO2 concentration in the closed-box model. Results indicate that the oxygen generation rate of KO2 oxygen plates, the oxygen generation efficiency, and the carbon dioxide absorption rate decrease when there is an increase in the pressure used to mold the oxygen plates, but those values increase when the initial CO2 concentration increases. When the initial concentration of CO2 in the dosed-box model is 3.5% and the forming pressure is 10 kN, the average oxygen generation rate of 15 g KO2 oxygen plate is 11.88 ×10^-3 L/min, the oxygen generation efficiency is 80.3%, and the average CO2 absorption rate is 11.0 × 10^-3 L/min. Compared with the condition where the initial CO2 concentration is 1.5%, the results show that average oxygen genera- tion rate of oxygen plates increases by 88,9%, the oxygen generation efficiency increases by 88.9%, and the CO2 absorption rate increases by 100%.

Recent strategies to enhance the efficiency of hematite photoanodes in photoelectrochemical water splitting

Photoelectrochemical(PEC)water splitting is one of the most promising approaches toward achieving the conversion of solar energy to hydrogen.Hematite is a widely applied photoanode material in PEC water splitting because of its appropriate band structure,non-toxicity,high stability,and low cost.Nevertheless,its relatively low photochemical conversion efficiency limits its application,and enhancing its PEC water splitting efficiency remains a challenge.Consequently,increasing efforts have been rendered toward improving the performance of hematite photoanodes.The entire PEC water splitting efficiency typically includes three parts:the photon absorption efficiency,the separation efficiency of the semiconductor bulk,and the surface injection efficiency.This review briefly discusses the recent advances in studies on hematite photoanodes for water splitting,and through the enhancement of the three above-mentioned efficiencies,the corresponding strategies toward improving the PEC performance of hematite are comprehensively discussed and summarized.

Thermo economic evaluation of oxy fuel combustion cycle in Kazeroon power plant considering enhanced oil recovery revenues

Oxy fuel combustion and conventional cycle(currently working cycle) in Kazeroon plant are modeled using commercial thermodynamic modeling software. Economic evaluation of the two models regarding the resources of transport and injection of carbon dioxide into oil fields at Gachsaran for enhanced oil recovery in the various oil price indices is conducted and indices net present value(NPV) and internal rate of return on investment(IRR) are calculated. The results of the two models reveal that gross efficiency of the oxy fuel cycle is more than reference cycle(62% compared to 49.03%), but the net efficiency is less(41.85% compared to 47.92%) because of the high-energy consumption of the components, particularly air separation unit(ASU) in the oxy fuel cycle. In this model, pure carbon dioxide with pressure of 20×105 Pa and purity of 96.84% was captured. NOX emissions also decrease by 4289.7 tons per year due to separation of nitrogen in ASU. In this model, none of the components of oxy fuel cycle is a major engineering challenge. With increasing oil price, economic justification of oxy fuel combustion model increases. With the price of oil at $ 80 per barrel in mind and $ 31 per ton fines for emissions of carbon dioxide in the atmosphere, IRR is the same for both models.

Studies on Recovery Efficiencies of Phenols from Phenol Fraction Using Alkali Treatment

Experiments were conducted for the extraction of phenols from the phenol fraction obtained from the coal tar distillate. The phenol fraction for the present investigation has been procured from Visakhapatnam Steel Plant, Visakhapatnam whose composition is known. The phenol fraction from coal tar distillate can be treated for extracting phenols using caustic soda. An attempt has been made to find out whether the existing practice of using only 8%-15% can be modified by increasing the strength of sodium hydroxide and also explore the possibilities of substituting the sodium hydroxide with KOH as an extractant. The different streams of liquids obtained during experimentation have been analyzed by gas chromatograph. Salient features of the study are that higher concentrations of the alkali significantly improved the separation efficiencies of phenols and also regenerate the phenolate with higher phenol content. Increase in the alkali strength has greatly improved the separation as well as the phenol content in the regenerated phenols. Disposal of effluents containing phenols may lead to environmental problem of ground water pollution and the study throws a light on the removal of phenols from the effluents to the extent possible by using higher strength alkali solutions.