PX型高效旋风分离器的冷模放大试验

为了评价实验室小型冷模试验开发出来的新型高效旋风分离器应用到工业过程中的性能,在完全相同条件下进行了与成熟的PV型旋风分离器的大型冷模放大对比试验.介绍了试验装置以及试验方案、内容.试验结果表明,新的PX型旋风分离器比现有的PV型旋风分离器具有更好的分离性能,分离效率更高(约高0.5～1.1百分点)、压力降更低、处理气量更大,对于催化裂化装置的扩能改造十分有利.     

高山被孢霉发酵生产花生四烯酸发酵条件优化

通过对一株高山被孢霉菌株（Mortierella alpina）发酵生产花生四烯酸（ARA）的摇瓶培养研究,以菌体干质量、出油率和ARA含量为标准,确定了其最佳发酵工艺条件。摇床实验确定的最佳培养条件为摇床转速180 r/min,培养基碳氮比为3.0,发酵温度为26 ℃,pH 值为6.2,发酵周期为5 d。在此发酵条件下,在10 L自动发酵罐进行放大发酵试验,菌体干质量、出油率和ARA含量分别高达45.4 g/L、24.1 g/L和49.6%。     

Mixing in upflow anaerobic filters and its influence on performance and scale-up

Tracer studies were carried out in laboratory-scale and pilot-scale upflow anaerobic filters to determine the effect of liquid velocity, gas production and media depth on mixing patterns. A computer simulation model was developed to analyse tracer-response curves. In water studies at laboratory scale, gas production was shown to have a significantly greater effect on mixing than liquid upflow velocity. A reduction in the quantity of media also resulted in greater mixing due to the greater void space in which synthetic gas bubbles could cause turbulence. In the presence of sludge during reactor operation, at pilot and laboratory-scale, gas production had a significant influence on mixing. However, liquid velocity played an important role in solids distribution in the filter, in conjunction with media depth. At pilot-scale, at a low solids concentration, a high liquid velocity lifted the sludge “bed”, raising the source of gas production. The absence of gas below the sludge bed resulted in a plug flow regime which the incoming substrate entered. A reduction in the quantity of media increased the degree of mixing for a given liquid velocity and gas surface load. Lower liquid upflow velocities are required at a reduced media depth to prevent excessive biomass loss. Shear rates increase at high liquid and gas velocities, resulting in detachment of solids from the media and biomass washout. A close correlation was established between mixing and process performance which led to the development of a programme for start-up and operation of the filter to maintain optimum biomass/substrate contact. A strategy for scale-up was proposed through the development of correlations obtained from laboratory-scale filter studies which were used to predict pilot-scale mixing characteristics. This research highlighted the important factors influencing mixing patterns and scale-up in anaerobic upflow filters.     

Effects of mixing on fed-batch fermentation of -ornithine

The effects of mixing on -ornithine fermentation were studied using an -arginine auxotrophic mutant of Brevibacterium ketoglutamicum ATCC 21092. Three different modes of fed-batch culture using two different impeller types were studied in a 7 l fermentor. The first two modes of fed-batch culture were carried out in a fermentor equipped with six-flat-blade disk-turbine impellers with top and bottom feeding. The third mode of fed batch culture was carried out using pitched-six-flat-blade disk-turbine impellers with top feeding. The titre of -ornithine increased up to 1.8 fold with bottom-feeding or when the pitched-six-flat-blade disk-turbine impellers were used compared to when the six-flat-blade disk-turbine impellers with top-feeding were used. It was observed that the mixing time of the limiting nutrients varied significantly depending on both the direction of feeding and the impeller type. Since the profiles of the specific rates of CO₂ evolution, oxygen and glucose uptakes were very similar for the three culture modes, it could be reasonably assumed that the microorganism exhibited similar growth rates for each mode used. However, different amino acid producing activities were observed in the three culture modes. From these results it is concluded that the productivity of -ornithine fermentation is significantly improved by shortening the mixing time of the limiting nutrient in the fermentor.     

An Investigation into Pressure Fluctuations and Improved Modeling of Solids Friction for Dense-Phase Pneumatic Conveying of Powders

The aim of this paper is to investigate into flow mechanism with the help of pressure signal fluctuations analysis and modeling solids friction in case of solids–gas flows for fluidized-dense-phase pneumatic conveying of fine powders. Materials conveyed include fly ash (median particle diameter 30 µm; particle density 2300 kg m^?3; loose-poured bulk density 700 kg m^?3) and white powder (median particle diameter 55 µm; particle density 1600 kg m^?3; loose-poured bulk density 620 kg m^?3). These were conveyed in different flow regimes varying from fluidized-dense-to-dilute phase. To obtain information on the nature of flow inside pipeline, static pressure signals were studied using technique of Shannon entropy. Increase in the values of Shannon entropy along the flow direction through the straight-pipe sections were found for both the powders. However, drop occurred in the Shannon entropy values after the flow through bend(s). Change in slope of straight-pipe pneumatic conveying characteristics along the flow direction is another factor which provided indication regarding change in flow mechanisms along the flow. A new technique for modeling solids friction factor has been developed using a solids volumetric concentration and ratio of particle terminal settling velocity to superficial air velocity by replacing the conventional use of solids loading ratio and Froude number, respectively. The new model format has shown promise for predictions under diameter scale-up conditions.     

油井采出液管式旋流预分水设备的放大设计

旋流分离设备逐渐成为油田解决高含水问题的关键技术之一,但放大后性能降低成为制约其工程化应用的主要因素。对比研究了直接理论设计、压力主导型相似放大设计和流量主导型相似放大设计3种放大设计方法;以处理量为1.0 m³/h的管式旋流预分水设备室内样机为原型,分别采用上述3种设计方法设计了处理量为10.0 m³/h的工程样机;通过数值模拟详细对比了流动特性,并开展了现场试验研究。结果表明,流量主导型相似放大设计方法所得设备不仅离心加速度最大而且轴向衰减率最小,最大切向速度衰减率仅为25.39%。该方法设计的工程样机在油田现场的运行效果与室内样机基本一致：当采出液含水率在75%~90%范围内时,在确保分水率大于50%的前提下,可以将水出口的含油质量浓度控制在1321 mg/L以下。综合来看,流量主导型相似放大设计方法具有计算周期短、实施方便等优点,可为旋流分离设备的放大设计提供理论指导。     

Effect of flow field distribution on the synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system

Scale-up synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system was investigated. Compared with traditional hydrothermal synthesis, the synthesis in a quasi-solid system has the advantages of high yield, short crystallization time, low energy consumption as well as low emissions. However, the high solid content in the quasi-solid system can cause the mass and heat transfer problems and make scalable production difficult. In order to solve the problem, we have developed a method for the optimization of the mass and heat transfer. By this method one can vary the flow field in the reactor by changing the stirrer speed. Scale-up synthesis of the sub-micron ZSM-5 molecular sieve in a quasi-solid system was carried out in a 5 L reactor with double propeller-type agitators. The process was investigated with product characterization using X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the flow field information was collected using laser Doppler velocimetry (LDV). The results showed that the flow field patterns can be tuned by using different stirrer speeds, the morphology and size of as-synthesized of ZSM-5 can be effectively controlled.     

Comparative Study on the Role of DPT on the Formation of HMX in Semi-Batch and Continuous Process

3,7-Dinitro-1,3,5,7-tetrazabicyclo-[3,3,1]nonane (DPT) is a key intermediate in the preparation of octahydro-1,3,5,7-tetranitro 1,3,5,7-tetrazocine (HMX), one of the most powerful high-melting explosives. The present investigation focuses on DPT formation during semi-batch and continuous processes. Qualitative and quantitative picture has been brought out to realize the role of DPT in HMX formation. The study reveals that only two thirds of DPT is formed in the continuous process as compared to that of semi-batch process. The calculated final yield of HMX on reaching steady state in the continuous process is comparable to the semi-batch process. This study also illustrates the usefulness in understanding the role of DPT in the final yield of HMX.     

食品挤压机的相似设计及其应用

本文依据能量原则、质量原则和产量原则建立了食品挤压机相似设计中所需的方程 ,论证了相似设计的可行性和可靠性 ,比较了模型机和试验机的挤出效果 ,最后给出了双螺杆挤压机相似设计的计算结果。实验研究表明挤压机的相似设计取得了良好的结果