Filtration in coal liquefaction.: 2. Relation between digestion conditions and filtration rate

In systems for the liquefaction of coal by solvent extraction, removal of the undissolved solids from the liquefaction products is a fundemental part of the process. For separation of solids by filtration to be economically viable, it is essential to achieve high filtration rates. The influence of the extraction conditions, temperature, residence time and coal feed size, on the rate of filtration has been investigated. It has been shown that the rate of filtration is sensitive to the presence of a gel-like intermediate formed during the dissolution of the coal. The formation of this intermediate imposes limitations on the choice of digestion conditions, in particular the coal feed size. However, by inducing polymerization, the gel can be stabilized, thus allowing significantly improved filtration rates to be achieved.     

煤液化过程中溶剂的作用

综述了近年关于煤液化反应中溶剂作用方面的研究成果，以及研究溶剂作用的新分析手段和研究方法。     

Recovery of liquid fuel from hydrocarbon-rich microalgae by thermochemical liquefaction

Liquefaction of Botryococcus braunii, a colony-forming microalga, with high moisture content was performed with or without sodium carbonate as a catalyst for conversion into liquid fuel and recovery of hydrocarbons. A greater amount of oil than the content of hydrocarbons in B. braunii (50 wt% db) was obtained, in a yield of 57–64 wt% at 300 °C. The oil was equivalent in quality to petroleum oil. The recovery of hydrocarbons was a maximum (>95%) at 300 °C.     

FORMATION AND FLOW OF GAS BUBBLES IN A PRESSURIZED BUBBLE COLUMN WITH A SINGLE ORIFICE OR NOZZLE GAS DISTRIBUTOR

The characteristics of gas bubbles in a 5 cm diameter bubble column equipped with a single orifice of 1,3 or 5 mm diameter were investigated under system pressure of 0.1-15 MPa. The formation of gas bubbles was strongly affected by the system pressure. Under high pressures a dispersed gas jet was formed at gas velocities where spherical gas bubbles would have been formed at atmospheric pressure. The critical gas velocity between the bubbling regime and the jetting regime was correlated with the liquid phase Weber number and the gas phase Reynolds number based on the gas velocity at the orifice. Bubble size and gas holdup in the main part of the bubble column were also affected by the bubble formation pattern at the distributor     

Study of Kansk-Atchinsk lignite liquefaction in lower aliphatic alcohols using flow periodical function

The action of lower aliphatic alcohols on lignite conversion to liquid products has been studied using flow periodical function. Ethanol and isopropanol were shown to be most active. The lignite conversion is accompanied by enrichment of the aliphatic fragment, both in the liquid and solid phase. The degree of condensing of the aromatic fragments in liquid increases with the enhancement of lignite conversion and does not depend on the alcohol species. Substitution degree of aromatic fragments and the number average molecular weight of liquids decreases in the order methanol ethanol isopropanol. I.r and ¹H n.m.r. data and elemental analysis have shown that alkylation both of liquid and solid products takes place during lignite liquefaction A linear relation between the quantity of aliphatic fragments in solid and the lignite conversion in ethanol is established.     

煤直接液化铁催化剂的研究进展(Ⅰ)担载铁催化剂的表征及研究方向

对高分散担载铁催化剂的表征方法如ＢＥＴ,ＳＡＸＳ,ＸＲＤ,ＥＸＡＦＳ,ＥＰＭＡ,ＸＰＳ,Ｍｏｓｓｂａｕｅｒ谱等作了述评,并指出存在的问题及可能的解决方法。要了解原位担载铁催化剂的化学组成,结构和在煤上的分散状况,必须采用多种分析手段综合进行,而现有任何手段都不能定量地测得催化剂在煤上的分散度。同时指出如何表述催化剂在煤直接液化中的作用,催化剂的活性与煤本身的哪些性质相互关联是煤直接液化担载铁催化剂     

我国煤炭直接液化技术及其工业应用前景

回顾了煤炭直接液化工艺的发展历史,分析了煤炭直接液化在我国能源结构中的地位,概述了国内主要研究成果和最新动态,强调了积极发展我国煤炭直接液化工艺的重要意义。     

土坝的地震响应及液化无网格法分析

以Biot固结理论的u-p列式作为饱和砂土的控制方程,应用有效循环弹塑性模型建立土的本构关系,并运用更新的Lagrange大变形算法分析液化后土体的大变形行为。利用移动最小二乘法近似推求形函数,再采用伽辽金法对控制方程离散,获得无网格伽辽金法的基本计算方程以进行无网格法分析。通过算例证明了该方法能避免液化大变形有限元分析时由于网格畸变而引起的计算中断问题。将无网格法应用于某坝的地震响应分析。计算结果表明：坝顶的加速度在液化前较输入加速度有一定的放大,在液化后加速度显著减小,且振动周期变长;坝体下部和坝趾处土体相对于其他区域不容易发生液化。     

饱和砂土流固耦合细观数值模型及其在液化分析中的应用

在饱和砂土连续力学模型的基础上,建立了一个饱和砂土固相颗粒和液相流体耦合的细观力学模型,固相颗粒采用离散元的颗粒流理论模拟,液相流体通过求解平均Navier-stokes方程的计算流体动力学技术计算。该细观模型用二维渗流问题进行了验证,并将其应用于饱和砂土的液化分析。数值模拟结果显示,采用的模型可以描述从低雷诺流到高雷诺流范围很大的流体运动。液化分析表明：液化首先在试样的表层产生,接着向深部发展;而超孔隙水压力则从底部开始消散,然后逐渐向上发展,直至完全消散。砂土液化过程中土体孔隙率不断变化,渗透系数也随之改变。     

对淮安市区粉土地基液化评价的思考

粉土中砂粒、粉粒、粘粒都存在,有着既不同于砂土也不同于粘性土的工程性质。淮安市区粉土由于粉粒占绝对优势,砂粒很少,使其液化特性又表现出不同于普通粉土的区域性特性。在总结国内外粉土地基液化评价及预测的研究成果、分析了其对淮安市区粉土的适用性的基础上,结合区域工程地质特征及土层分布等情况,对淮安市区粉土的液化可能性评价及研究方法提出了有益的思考。