【作者】 计建炳；

【导师】 谭天恩；

【作者基本信息】 浙江大学 ， 化学工程， 2002， 博士

【摘要】 本文研究的复合塔板是在穿流筛板之下紧贴一层50～150mm的规整填料所构成，它有三个传质区，即塔板上的泡沫区、填料层内的液膜区以及填料层下的淋降区，因此，具有很高的传质效率。复合塔板不设降液管，气液同时逆流穿过筛孔。本文根据复合塔板的气液流动特点，分析了气液穿孔流动的机理。根据前人的研究结果，提出复合塔板在操作时，由于泡沫层的波动，其筛孔存在通气、通液和阻塞三种状态。波峰对应的筛孔通液，波谷对应的筛孔通气，波腰对应的筛孔处于阻塞状态。随着波的运动，处于通液、通气和阻塞状态的筛孔不断变化。同一时刻三种状态的筛孔数与总筛孔数之比，分别称为通液率、通气率和阻塞率。 采用多路电导测试仪，在直径500mm的冷模塔内，以空气-水为介质，首次较系统地测量了开孔率为20％和25％的复合塔板的通气、通液和阻塞筛孔的数量比例，获得了通气率、通液率和阻塞率随气液变化的基本规律。此外，实验发现，不同喷淋密度下，复合塔板液泛时的筛孔真实气速均为11m／s左右，据此，可推算出复合塔板的操作上限。 复合塔板的压降可认为由干板压降、清液层阻力、填料层压降和克服液体表面张力的压降四部分组成，所建立的压降计算模型，能较好地预测复合塔板的压降，计算值与实验值误差在±20％以内，可用于工程设计。此外，根据复合塔的流体力学性能，确定了其操作范围的计算方法。 在直径300mm的精馏塔内，以乙醇-水为介质，进行了复合塔板、穿流筛板、筛板和浮阀塔板的传质效率的研究。测定了复合塔板的全塔效率、塔板效率、泡沫区和液膜区效率以及其余三种塔板的效率。实验表明，复合塔的全塔效率和单板效率在F因子1～2.5m／s(kg／m3)”’范围内，可超过 100％，最高效率达 122％，远高于穿流筛板、筛板和浮阀塔板的效率。填料层的效率依据所复合的填料层高度的不同，分别可占到效率的 20％～53％。 在 200mm X 300nun的有机玻璃方塔内，以空气－水为介质，采用 CCD拍摄技术和塔内气液两相流计算辨识技术，测定了开孔率为20％的复合塔板上泡沫层的气液接触比表面积，并建立了关联式。为建立泡沫层的传质模型，提供气液接触比表面积的实验数据。 以溶质渗透理论为基础，建立了泡沫层的传质模型，根据泡沫层的传质模型和规整填料的FBR传质模型，获得了预测复合塔板传质效率的模型。模型的预测值与实验值的上偏差在 20％以内，负偏差在 15％以内。更多还原

【Abstract】 The Compound tray researched in this paper consists of dual-flow tray and 50-1 ^Omm high structural packing which is directly put under the dual-flow tray. It has three mass transfer sections that is the foam section on the tray, the film section in the packing layer and the shower section under the packing, so it has very high mass transfer efficiency. The compound tray has no down comer, gas and liquid counter flow through the holes of on the tray. This paper analyzed the mechanism that gas and liquid flow through the holes according to the fluid characteristics of the compound tray, and put forward that there are three states of liquid flowing, gas flowing and blocked for the holes because of the foam fluctuating on the tray while the compound tray operates . Liquid flows through the holes under wave crest, gas flows through the holes under trough and neither liquid nor gas flows through the holes under the wave middle that means the holes are blocked. The state of the holes changes continuously along with the moving waves. At the same time the number of holes for liquid flowing, gas flowing and blocked to the number of total holes was defined as liquid flowing ratio, gas flowing ratio and blocked ratio.The experiment was made with in-diameter 500mm column using water-air system, the ratio was first delected in detail by multi-path conductivity gauge for the compound tray with free area 20% and 25% respectively. The basic regulation of the ratio which changes along with the flo\v rate of liquid and gas was obtained; besides, the experiments discovered that the real velocity of the holes at flooding point is about llm’s under different liquid flow rate, according to this the up limit of the compound tray can be reckoned .The pressure drop of the compound tray can be regarded as consisting of dry plate pressure drop, clear liquid resistance, liquid surface tension resistance, and packing pressure drop. The model that has established can fairly predict the pressure drop of the compound tray, the value calculated by the model compared with that detected by experiment is less than 20%. so the model can be used for designing of the compound tray: besides, a calculating method was gained for operating region of the compound tray on the basis of its characteristics .The test was made on the compound tray, dual flow tray, sieve tray and valve tray for mass transfer efficiency with in-diameter 300 mm column using ethanoi and water system. The total efficiency, plate efficiency, foam efficiency, film efficiency of compound tray, and the total efficiency of the other thee types of plate was detected. The experiment’s results show that the total and plat efficiency of the compound tray is over 100%, the highest efficiency can be up to 122% within the range of F factor I~2.5m/s(kg/m3)i/2, it is far higher than the efficiency of dual flow tray , sieve tray and valve tray . The efficiency of compounded packing can reach 0.2~0.53 theoretical plate according to the different height of packing.The special area of foam was detected for the compound tray of 20% free area by CCD camera and computer identification technology of gas and liquid two phase flow in column . with the rectangular plexiglass tower in 200mm X 300mm, and it’s correlation was obtained .This experiment offered data of special area for establishing mass transfer model of foam.The mass transfer model of the foam was established on the basis of the penetration theory, and the mass transfer model of the compound tray was obtained according to the mass transfer model of the foam and FRB model in packing. The error of the model value comparing to the experiment value is less than +20% and -15%.更多还原