PET连续固相缩聚工艺及主要影响因素

介绍了大连合成纤维研究设计院自主研发的10 kt/a连续式固相缩聚技术的生产工艺。从切片形状、结晶度及结晶形态、缩聚前预热、缩聚时间、氮气的纯度及流量等方面,讨论了固相缩聚主要影响因素。     

PET主要品质指标影响因素探讨

从生产实际角度,探讨了PET产品主要品质指标的影响因素,如色值、端羧基值、二甘醇值及特性黏度等受温度、压力、原料配比、添加剂品质等的影响情况。     

Numerical simulation on dense phase pneumatic conveying of pulverized coal in horizontal pipe at high pressure

A kinetic–frictional model, which treats the kinetic and frictional stresses in an additive manner, was incorporated into the two fluid model based on the kinetic theory of granular flow to simulate three dimensional flow behaviors of dense phase pneumatic conveying of pulverized coal in horizontal pipe. The kinetic stress was modeled by the kinetic theory of granular flow, while the friction stress is from the combination of the normal frictional stress model proposed by Johnson and Jackson [1987. Frictional–collisional constitutive relations for granular materials, with application to plane shearing. Journal of Fluid Mechanics 176, 67–93] and the modeled frictional shear viscosity model proposed by Syamlal et al. [1993. MFIX documentation and theory guide, DOE/METC94/1004, NTIS/DE94000087. Electronically available from http://www.mfix.org], which was modified to fit experimental data. For the solid concentration and gas phase Reynolds number was high, the gas phase and particle phase were all treated as turbulent flow. The experiment was carried out to validate the prediction results by three kinds of measurement methods. The predicted pressure gradients were in good agreement with experimental data. The predicted solid concentration distribution at cross section agreed well with electrical capacitance tomography (ECT) image, and the effects of superficial velocity on solid concentration distribution were discussed. The formation and motion process of slug flow was demonstrated, which is similar to the visualization photographs by high speed video camera.     

浅析粗对苯二甲酸产品透光率及其影响因素

简要阐述了CTA产品的透光率与PTA产品b值的相互关系,通过控制CTA的透光率,可保证PTA的b值,达到提高PTA产品品质的目的。结合生产实际,分析了PX纯度、氧分压、反应停留时间、反应器回流、母液循环率、二次氧化、无机杂质等对透光率的影响规律。     

Visual analysis of particle bouncing and its effect on pressure drop in dilute phase pneumatic conveying

During the pneumatic conveying of plastic pellets, it has been observed that materials with similar physical characteristics may develop substantial difference in pressure drop, whose cause is not fully understood. This experimental study focused on the dynamic behavior of the particles during conveying and its influence on pressure drop.The bouncing of the particles during pneumatic conveying in dilute phase was visually analyzed by means of a high speed video camera. The experiments included two different plastic pellets of similar size and density but different modulus of elasticity. The conveying trials were carried out in a 0.052 m I.D. aluminum pipe conveying system approximately 35 m long. The loading was controlled by an airflow control valve and a variable speed drive rotary valve. For each material, a series of tests were performed creating a matrix of six solids rates for five different air velocities. During the conveying trials a high speed video camera was used to record the actual particle motion in a horizontal section with fully accelerated flow. The videos showed significant difference in bouncing between the soft and the hard pellets. The soft pellets showed very random and intense bouncing with strong rotation, which affected the rebound considerably. In fact, some particles bounced even backwards. On the other side, the hard pellets showed significantly less bouncing and rotation.In addition to the high speed videos, in each test the pressure drop was measured in the horizontal and vertical directions. As expected, a significant difference in pressure drop was recorded for the same conveying settings when using the different materials. The pressure drop showed a close relation to the bouncing of the particles, being much higher for the soft pellets.It can be concluded that the increased pressure drop, developed by the soft polyethylene pellets, is in part due to the multiple times the particles must be reaccelerated during their transit through the conveying system. Additionally, the reduction in the average particle velocity increases the drag force. All of this resulted in up to 3-fold increase in pressure drop across the conveying line compared to the hard polyethylene pellets that showed significantly less bouncing.     

胶接用胶粘剂固化过程中温度预测及影响因素研究

针对单搭接接头,根据胶粘剂固化过程中的传热情况,将其温度场简化为无内热源的热传导问题,将平均换热系数看作固化温度的函数,采用集总参数法,得到胶粘剂固化过程中温度的预测公式,并用实验对公式计算结果进行了验证。运用该公式,分别讨论了固化温度、固化时间、被粘物材料属性、被粘物厚度、搭接长度、被粘物长度、胶粘剂初始温度、搭接宽度对胶粘剂固化过程中的温度影响规律。结果表明,前面5个因素对胶粘剂固化过程中的温度影响较大,后面两个因素基本无影响,当搭接长度相同,且与被粘物长度比值小于0.3时,被粘物长度也基本无影响。     

聚二甲基硅氧烷的改性技术及其渗透汽化性能的影响因素

介绍了聚二甲基硅氧烷(PDMS)的改性技术,总结了不同改性方法在渗透汽化中的应用,分析了影响PDMs膜渗透汽化性能的影响因素,指出了PDMs膜存在的问题及其发展方向.     

盐水精制过程及影响因素

综述了盐水精制过程,浅析影响因素,结合澄清桶内盐水净化过程,探讨提高出力和净化效果的一些措施。     

低压法焦炉气制甲醇的影响因素探讨

介绍了10万t/a低压焦炉煤气制甲醇装置的工艺流程,采用C307铜基甲醇合成催化剂。结合实际生产数据,分析了影响甲醇产率的主要因素,包括原料气(焦炉气)气量、压力、温度、空速、氢碳比、催化剂的毒物以及设备性能。生产操作和经验表明,提高甲醇产率需要多因素综合考虑,在气量一定的条件下,温度与压力波动越小,甲醇产量越高;根据动力消耗和催化剂生产强度,空速一般控制在4 000~20 000 h-1;在入塔气中φ(CO2)一般控制在2%~5%,对甲醇合成有利;硫化物、氯化物以及羰基铁等金属毒物必须有效脱除,以提高甲醇合成产率,并延长催化剂使用寿命;通过提高设备性能,可以保持生产的稳定性,提高甲醇产量。     

UV厌氧胶的制备及其影响因素研究

以聚氨酯丙烯酸酯(PUA)为基体、甲基丙烯酸-β-羟乙酯(HEMA)为活性稀释剂、异丙苯过氧化氢(CHP)为引发剂、N,N′-二甲基苯胺为促进剂、糖精为助促进剂、二苯甲酮(BP)/叔胺为光引发剂和对苯二酚为稳定剂,采用双引发体系和双固化[UV(紫外光)、厌氧固化]体系制备PUA基UV厌氧胶。通过单因素试验法优选出制备UV厌氧胶的最佳工艺条件。结果表明:当w(HEMA)=20%、w(CHP)=2%、w(光引发剂)=3.0%、w(N,N′-二甲基苯胺)=w(糖精)=0.8%和w(对苯二酚)=0.06%时,UV厌氧胶的综合性能良好,其光固化定位时间为8 s、剪切强度超过5 MPa。     

复合肥料的吸湿性及其影响因素

通过对复合肥吸湿性能的测定,得出各种配方复合肥的临界相对湿度,并对复合肥临界相对湿度与物料温度、原料成分之间的关系进行了研究,指出硝基复合肥的临界相对湿度受m(硝铵)/m(磷铵)的影响明显。     

地层压力预测技术及其在川东北河坝地区的应用

该区纵向上存在多个压力系统。准确预测地层压力有助于减少井下复杂事故,实现高效、安全钻井并保护储层。根据伊顿法计算地层压力的原理,优化模型参数,利用现场录井、钻井和测井资料,对该区地层压力纵向上的变化规律进行综合分析,划分压力系统。最终得到了精度较高的预测结果,满足工程需要。     

The influence of particle shape on flow modes in pneumatic conveying

The transportation of particles along pipes or ducts using an imposed gas flow is known as pneumatic conveying. The type of granular flow in such systems is strongly dependent on the imposed gas flow rate, and can be categorised by a distinct set of modes. These modes range from dilute flow, where the grains are entirely suspended in the gas, to moving dunes and slug flow, in which the bore of the pipe is blocked by a slow moving plug of material. Understanding the transitions between these modes is critical to the design and application of pneumatic conveying systems. Particle shape is a crucial factor in systems with gas–grain interactions but has so far been overlooked in models of pneumatic conveying. We carry out a series of simulations using the discrete element method coupled to gas flow and show that particle shape is critical to the transition between different flow modes. Particles which are spherical, or nearly spherical, transition to slug flow at high gas flow rates, whereas non-spherical particles transition instead to dilute flow. We show the lower voidage fraction in beds of non-spherical particles is crucial to explaining this behaviour.     

龙滩坝矿段采场结构参数及地压控制数值模拟研究

龙滩坝矿段矿体的直接顶底板大多为铝土页岩和黏土岩,顶板稳固性较差,有必要对开采过程中的采场稳定性进行模拟分析。采用3D-σ数值模拟软件建立三维模型,设计了直接顶板下不同采场跨度、切顶后不同采场跨度、留点柱等采场结构形式,对各种采场结构下矿岩的应力、位移、塑性区和安全率的分布进行了分析,结果表明:因矿体直接顶板稳定性较差,采场跨度对顶板稳定性的影响较大,应将采场跨度控制在6 m左右,才能保证开采过程中的顶板稳定;通过对切顶方案的模拟分析,认为将稳定性较差的直接顶板切除后,在间接顶板下采场跨度能达到15 m左右;根据模拟结果并结合现场实际情况,采场应预留3 m×3 m的点柱,点柱间矿块的跨度宜控制在6 m,以保证采场直接顶板的稳定。     

Online prediction of mass flow rate of solids in dense phase pneumatic conveying systems using multiple pressure transmitters and multivariate calibration

In many industries particulate materials are conveyed pneumatically, and it is both important and challenging to measure the mass flow rate of solids in a gas-solid mixture online.In this article we present some results from experiments carried out on a semi-industrial pneumatic conveying system located at the Department of Powder Science and Technology, Tel-Tek in Porsgrunn, Norway. We have successfully calibrated a regression model which relates the pressure distributions along the pipeline to the mass flow rate of powder. The method for mass flow rate estimation presented in this paper is based on multivariate calibration (chemometrics).Twenty-one pressure transmitters are distributed along the entire length of a pneumatic conveying system. The pressure samples from all transmitters constitute axial pressure distribution signatures, which in this study are used to calibrate a Partial Least Squares Regression model. When the Partial Least Squares Regression model is properly calibrated and validated, the model can be used to predict powder mass flow rate directly from new pressure signatures in the pneumatic conveying system used, under the same conditions of pressure and air flow.The results show that it is not necessary to use all the pressure transmitters available to predict mass flow rate. This paper presents promising results using only 5 pressure transmitters. Pressure transmitters are inexpensive, reliable and easy to use, and are widely used in the industry. This method has been tested with different values of pressure and air flow rates, with equally promising results. All prediction results are validated with independent data.     

水平分支管路气力输送阻力特性的预测

在水平T型分支管道中,用压缩空气作为输送气体,对平均粒径为0.25 mm和0.5 mm的砂石进行气力输送试验。通过试验和GRNN神经网络对输送表观气速和两分支管路流量控制阀开度发生变化时,各分支管路中的阻力特性进行了研究。结果表明:随着表观气速的逐渐减小和两分支管路流量控制阀开度差值的增加,各分支管路中的阻力特性相应地发生了变化。通过试验值和GRNN网络模拟值的对比,发现试验值和模拟值间相互吻合得较好,说明采用GRNN网络来模拟两分支管路中各自的阻力特性适应性较好。     

Reasearch on the main factors for changes in pressure based on turbulent circulating fluidized bed coal gasification technology

High temperature preheated air and steam as gasifying agent and coal gasification was performed in a pressurized turbulent circulating fluidized bed (CFB) gasification pilot plant to investigate the pressurized gasification process and estimate its potential. Within the scope of this paper this test facility as well as its operation behavior was described. Furthermore, the parameter pressure has been investigated regarding its influence on the syngas composition and was presented and discussed in the following. The results show that the gasification quality is improved at higher pressure because of the better fluidization in the reactor. Coal gasification at a higher pressure shows advantages in lower heat value and carbon conversion. With the gasifier pressure increased from 0.1MPa to 0.3MPa, the gas heating value is increased by 15%. Increasing the gasifier pressure would increase the carbon conversion from 57.52% to 76.76%. Also, the dry gas yield and efficiency of cold gas increase little with the increase of the gasifier pressure. The operating parameter of pressure exists at optimum operating range for this specific CFB coal gasification process.     

试论输油管道先导式轴流泄压阀渗漏的主要因素及解决方法

伴随着突然升高的输油管道压力,如果升高值超出了预先设定的泄压阀的压力值的话,压力就会经由泄压阀被泄至储油罐或者泄放管道里,有效的保护输油管道。尽管如此,泄压阀仍然比较频繁的发生渗漏事故,最终影响到功能的有效实现。基于此,本文主要对输油管道先导式轴流泄压阀渗漏的主要因素及解决方法。