Study of transpiring fluid dynamics in supercritical water oxidation using a transparent reactor

The transpiring wall reactor (TWR) is considered to be one of the most promising reactors because it minimizes both corrosion and salt precipitation problems that seriously hinder the industrialization of supercritical water oxidation technologies. A transparent reactor is built to study the fluid dynamics of transpiring flow, which are the foundation of reactor design and optimization. The results showed that the transpiring flow is anisotropic with respect to the surface of the transpiring wall due to both the static pressure and viscous resistance. Finally, the novel idea of using air as the transpiring fluid instead of water is presented in an attempt to alleviate current TWR problems such as high energy consumption, high volume of pure water consumption, and temperature fluctuation in the reaction area. A series of experiments and theoretical derivations demonstrate that this novel idea is feasible.     

A novel concept reactor design for preventing salt deposition in supercritical water

Reactor plugging and corrosion are the key problems which hinder commercial applications of supercritical water oxidation and gasification, and can be efficiently overcome by preventing salt deposition on internal surface of reactor. In this work the problems caused by salt deposition and the correspondingly main solutions are further reviewed objectively. A novel reactor is designed and manufactured with a feed rate of about 100 L/h for sewage sludge treatment. The reactor combines the characteristics of Modar reactor and transpiring wall reactor for the first time, which is expected to prevent reactor plugging and corrosion as well as to decrease catalyst deactivation rate. The reactor is the core equipment of the first pilot-scale plant for supercritical water oxidation in China. Further optimizations of reactor configuration and operational parameters need plenty of experiments and/or a long-time test with sewage sludge in the subsequent work.     

Study on the uniformity of water film in a transpiring wall reactor for supercritical water oxidation

A three-dimensional computational fluid dynamic model of a transpiring wall reactor for supercritical water oxidation has been built to optimize the uniformity of water film. Results show that the temperature and species distributions at the nozzle outlet deviate from the reactor centre. The inner wall of the porous tube near the transpiring water injection tube displays low temperatures, while high temperatures are recorded far from the injection tube. The circumferential temperature distribution on the inner wall of the porous tube is uneven. This phenomenon is due to the uneven injection of the transpiring water, leading to the uneven protection of the water film and local overheating of the porous wall. The injection velocity of the transpiring water significantly decreases when the number of injection tubes is increased, and the circumferential velocity and temperature distributions on the porous wall gradually become even. Moreover, high pressure drops across the porous wall at low porosities are useful for the uniform injection of the transpiring water. This characteristic is also conducive to obtaining a more uniform water film protection.     

Effects of structural parameters on water film properties of transpiring wall reactor

Corrosion and salt deposition problems severely restrict the industrialization of supercritical water oxidation. Transpiring wall reactor can effectively weaken these two problems by a protective water film. In this work, methanol was selected as organic matter, and the influences of vital structural parameters on water film properties and organic matter removal were studied via numerical simulation. The results indicate that higher than 99% of methanol conversion could be obtained and hardly affected by transpiration water layer, transpiring wall porosity and inner diameter. Increasing layer and porosity reduced reactor center temperature, but inner diameter's influence was lower relatively. Water film temperature reduced but coverage rate raised as layer, porosity, and inner diameter increased. Notably, the whole reactor was in supercritical state and coverage rate was only approximately 85% in the case of one layer. Increasing reactor length affected slightly the volume of the upper supercritical zone but enlarged the subcritical zone.     

Transpiring wall reactor in supercritical water oxidation

Reactor corrosion and plugging problems have hindered the commercialization of supercritical water oxidation (SCWO) for wastewater purification. The use of transpiring wall reactor (TWR) is an effective means to overcome the above two problems by forming a protective water film on the internal surface of the reactor to aviod contacting corrosive species and precipitated organic salts. This work mainly aims to objectively review experimental investigations and numerical simulation results concerning TWR. Subsequent investigations for parameters optimizations of TWR are also proposed in order to ultimately build effective regulation methods of obtaining excellent water film properties. All this information is very important in guiding the structure design and operation parameters optimization of TWR.     

国外超临界水氧化技术的研究现状

超临界水氧化是水处理技术发展的新方向,但该技术对设备的要求比较高,工业化应用仍有一定的难度。为了克服这一难题,目前的研究工作主要集中在催化剂的选择以及设备防腐蚀等方面。介绍了贵金属类催化剂、过渡金属类催化剂、碱金属盐类催化剂、杂聚酸类催化剂以及碳基类催化剂,在降解不同污染物时的催化效率。在反应器材质和反应器形式的研究中,分别对铁、镊、铬等纯金属以及不同材料的合金在各种条件下的防腐蚀性能作了比较;两种最新的反应器形式:可蒸发壁式反应器和流动式反应器。它们在超临界水氧化中表现出了良好的防腐能力。     

CFD simulation of a transpiring‐wall SCWO reactor: Formation and optimization of the water film

A two‐dimensional axisymmetric computational fluid dynamics model of a transpiring wall reactor for supercritical water oxidation was developed using the commercial software Fluent 6.3. Numerical model was validated by comparisons with experimental temperature profiles and product properties (total organic carbon and CO). Compared with the transpiration intensity, the transpiring water temperature was found to have a more significant influence on the reaction zone. An assumption that an ideal corrosion and salt deposition inhibitive water film can be formed when the temperature of the inner surface of the porous tube is less than 374°C was made. It was observed that lowering transpiring water temperature is conducive to the formation of the water film at the expense of feed degradation. The appropriate mass flux ratio between the total transpiring flow and the core flow was determined at 0.05 based on the formation of the water film and feed degradation. © 2015 American Institute of Chemical Engineers AIChE J, 62: 195–206, 2016     

一体式再生燃料电池性能

报道了反应条件对一体式再生燃料电池单体电池性能的影响,并对单体电池的极化特性和循环稳定性进行测试。结果表明：URFC单体电池表现出优异的电性能和良好的循环稳定性。双模式工作条件下,反应温度控制在60～70 ℃比较合适。在燃料电池模式下,提高氧气压力可以更显著的提高电池性能;在氢气相对湿度为100%条件下,氧气相对湿度对电池性能影响不大,当电流密度大于500 mA/cm²时,采用干态氧气和相对湿度为100%氧气时,电池性能趋于一致。     

含氯介质超临界水氧化过程中几种镍基合金腐蚀的实验研究

超临界水氧化过程中,含氯化合物水溶液对普通不锈钢具有极强的腐蚀性. 使用超临界水氧化反应装置,研究了4种镍基合金不锈钢试样(1Cr18Ni9Ti, 316L, 0Cr18Ni12Ti和QLC12)在超临界水氧化过程中(400~620℃, 28~32 MPa)处理含氯废水时的腐蚀情况. 经过30 d的实验,用金相光学显微镜和扫描电子显微镜观测试样腐蚀的形貌. 结果表明,4种合金在15%(w)含氯水溶液中经过超临界水氧化反应均存在腐蚀. 对腐蚀速率进行了测试,其中1Cr18Ni9Ti和316L腐蚀速率较大,而QLC12腐蚀速率最小,为0.06 mm/a, 可用于制造反应器. 实验发现0Cr18Ni12Ti存在晶间腐蚀现象. 同时对腐蚀机理进行了分析.     

Catalytic oxidation of NO over Ce-doped Mn/TiO2

Mn-Ce/TiO₂ catalyst was prepared by impregnating Mn-Ce on TiO₂ and was characterized by XRD,BET and PL. The influences of Ce-doping concentration,loading,calcinations temperature,space velocity,inlet concentration of NO and volume fraction of oxygen on the performance of catalytic oxidation were examined. The results showed that the effect of doping Ce not only increased the surface area of MnO_x/TiO₂ but also enhanced the dispersion of active phase over TiO₂. At Ce-doping concentration of [Ce]/[Mn]=1/3,10% loading Mn-Ce/TiO₂ catalyst calcined at 300 ℃ for 3 h had high catalytic oxidation activity. When inlet concentration of NO was 300 μL/L,O₂ 10%,space velocity was 41000 h^－1,oxidation rate of NO over Mn-Ce/TiO₂ reached 58% at 200 ℃.     

一种新型炭载体在乙炔氢氯化反应中的应用

采用等体积浸渍法制备了一系列不同载体的HgCl₂催化剂,利用BET、原子荧光光谱仪（AFS）、元素分析仪（EA）等对样品进行了表征,考察了催化剂在固定床反应装置上进行乙炔氢氯化反应的性能,同时对催化剂失活原因进行了初探。结果表明,不同载体催化剂催化性能和失活原因差异很大,其中以AC-2（沥青基球形炭）为载体的HgCl₂/AC-2催化性能最佳,当HgCl₂含量为5%（质量分数）、乙炔空速36 h^－1、温度140 ℃、n(HCl)∶n(C₂H₂)=1.05～1.1时,其初始转化率>99%（比HgCl₂/AC-1提高39%）,选择性接近100%,寿命可达3168 h,催化性能优于现有工业高汞催化剂。     

Ce-Mo-Ti-V催化制备苯四甲酸二酐

开发了一种由均四甲苯空气气相氧化制均苯四甲酸二酐过程所需的催化剂,该催化剂活性组分为Ce-Mo-Ti-V。通过实验研究了载体种类、活性组分、温度、空速和反应物浓度对工艺结果的影响。实验表明：在空速6 000 h^－1,温度为455℃,均四甲苯浓度为20 g/m³时,均苯四甲酸二酐的质量收率达到101.7%。     

甲苯液相催化氧化过程稳态模拟

通过分析甲苯氧化反应的特点,依据反应动力学模型和物料衡算关系,提出了对甲苯液相催化氧化过程进行稳态模拟的方法,研究了稳态连续操作时反应温度、进料甲苯流量等操作条件对苯甲酸浓度的影响。采用的反应动力学模型考虑了苯甲醛、苯甲醇等组分对反应的影响,并用生产数据对反应动力学参数进行了重新回归。使用回归得到的动力学参数进行稳态模拟,结果显示：苯甲酸质量分数的计算值与测量值的相对误差在5%以内。     

固定化假丝酵母脂肪酶催化合成辛酸甘油酯

以自制固定化假丝酵母脂肪酶作为催化剂,研究了无溶剂体系中辛酸和甘油直接酯化合成辛酸甘油酯的反应条件。考察了酶的种类、底物的物质的量之比、温度、酶量、甘油的初始含水量和反应时间等因素对辛酸转化率和产物组成的影响。结果证明,以纺织物作为载体制备的固定化假丝酵母脂肪酶适宜催化辛酸甘油酯的合成。最优反应条件为：辛酸与甘油的物质的量之比为2∶1,固定化假丝酵母脂肪酶加量为0.5g/0.69g甘油,温度为40 ℃,振荡培养箱转速为190 r/min。最优反应条件下辛酸转化率可以达到94%以上,经过简单处理的固定化酶可以重复使用4批。     

超重机中的气液直接传热性能

采用热空气-水体系,在转速为200～1400 r/min、水流量为40～140 L/h、热空气范围为3～15 m³/h的实验条件下,研究了热空气-水在超重机中的传热性能。实验结果表明：总传热系数随着转速的升高而增大,随着水流量的增加而增大,但增幅减小,随着热空气流量的增加而增加。对传热单元高度的计算和分析也验证了传热效果的增强。最后推导出传热系数关联式,且进行了统计检验,所得关联式与实验数据拟合较好。     

我国原油供应战略安全分析

石油是国家的重要资源,是支撑国民经济发展的重要保障。原油供应安全对国民经济的发展起到举足轻重的作用。本文从7个比较重要和具有代表性的评价指标方面详细分析了我国原油供应安全的现状和未来的发展趋势。经过分析发现我国原油的供应状况正处于极度危险的状况。     

A/O1/O2生物膜系统污染物降解特性

将传统A/O工艺的好氧单元分为两段,在各反应器中设置填料,构建了A/O₁/O₂生物膜系统,对锦纶废水进行处理,研究了污染物在系统各段的降解情况,并借助红外光谱分析方法探讨了污染物中官能团的变化规律。结果表明,A/O₁/O₂生物膜系统处理锦纶废水的效果良好,COD、NH₄⁺-N和TN的平均去除率分别为92.70%、85.35%和58.85%。当有机负荷从1.64～4.61 kg/(m³·d) 变化时,A段、O₁段和O₂段中COD、NH₄⁺-N和TN的降解变化趋势均不相同。对于COD的去除,A段、O₁段和O₂段的平均贡献率分别为63.08%、29.72%和4.16%;对于NH₄⁺-N的去除,O₁段和O₂段的平均贡献率分别为23.80%和75.99%;对于TN的去除,A段、O₁段和O₂段的平均贡献率分别为74.97%、19.77%和4.09%。经A段缺氧、O₁段和O₂段好氧处理后,废水中酰胺化合物、氨基酸和脂肪族化合物含量减少,出现了无机的NH₄⁺、NO₃^－、HCO₃^－以及碳水化合物。     

Influence of alkylaluminium on TiClx/ MgCl2/ THF catalyst——Effect of Al-alkyl on chemical structure and catalyst performance

研究了一系列不同烷基铝处理的TiCl_x/MgCl₂/THF体系Ziegler-Natta催化剂,并采用XPS、EPR对其化学结构进行表征,初步探讨了烷基铝变化对催化剂化学结构的影响,特别是对Ti价态的影响。研究结果表明,由于烷基铝的作用,催化剂中活性组分Ti的结构发生了明显的改变,而其中烷基铝预还原过程对催化剂的结构影响较大。借助催化剂的这些结构上的变化引起其催化性能的显著提高,对比评价结果表明,小试催化剂的乙烯均聚活性从预还原前的4890 gPE/gcat提高到9300 g PE/gcat,工业生产催化剂从8400 g PE/gcat提高到11000 g PE/gcat。     

微波辐射下聚醚改性聚硅氧烷的合成及其乳液的性能

以含氢硅油与封端聚醚为原料,在微波辐射条件下合成出了聚醚改性聚硅氧烷,利用红外光谱对其结构进行了表征,采用均匀设计法对合成参数进行了优化,优化条件为：微波功率为650 W,封端聚醚与含氢硅油的摩尔比取1.1∶1,添加质量比为15 mg/kg的氯铂酸催化剂,于100 ℃反应30 min,在该条件下,平均转化率为96.8%。以合成的聚醚聚硅氧烷为主要活性单体制备出了消泡剂乳液,并考察了温度、pH值对制备的消泡剂性能的影响,结果表明制备的消泡剂在常温到98 ℃,酸性或碱性条件下的消泡及抑泡性能良好。