本文選題：臨界懸浮特性　切入點(diǎn)：通氣攪拌功率　出處：《北京化工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：攪拌是工業(yè)生產(chǎn)一項(xiàng)常見的操作,由于其適用性強(qiáng)的特點(diǎn),小到實(shí)驗(yàn)室操作,大到化工、冶金、制藥、生物工程等大型工業(yè)都離不開攪拌單元操作。近年來隨著攪拌裝置的日益大型化,對(duì)多層槳攪拌槽的研究成為一個(gè)熱點(diǎn)。已有研究表明,以徑向流槳為底槳,軸流式槳為中、上層槳更利于氣液的分散。本文采用前人在氣液兩相攪拌槽中優(yōu)化得到的槳徑與槽徑比D/T為0.33的組合槳型PDT+2CBY(其中底槳為PDT槳,即徑向流型的拋物線盤式渦輪槳,上兩層槳為軸向流式的長(zhǎng)薄葉螺旋槳CBY槳),在氣液固三相體系中進(jìn)行氣液分散及固液懸浮性能的深入研究。本研究涉及兩種不同的氣液固三相體系,首先在空氣-水-玻璃微珠(ρ=2500 k·m-3)體系中,研究采用PDT+2CBY組合槳的臨界懸浮特性、通氣攪拌功率和整體氣含率。研究結(jié)果表明：1、臨界懸浮特性：隨著表觀氣速VS和固含率Cv的增加,臨界懸浮轉(zhuǎn)速NJSG和臨界懸浮單位質(zhì)量功率PmJSG皆隨之增大。2、通氣攪拌功率：隨著通氣速率和攪拌轉(zhuǎn)速的增大,相對(duì)功率需求RPD皆不斷減小并最終趨于穩(wěn)定；在一定的攪拌轉(zhuǎn)速下,RPD隨固含率Cv的變化幅度不大,基本在10%以內(nèi)。3、整體氣含率：隨著表觀氣速VS和單位質(zhì)量功率PTm的增大,氣含率隨之增大；VS和PTm相同時(shí),攪拌槽中的整體氣含率隨Cv增加而減小。在空氣-水-樹脂顆粒(ρ:1300kg·m-3)體系中進(jìn)行類似研究,結(jié)果表明：1、臨界懸浮特性：在不同表觀氣速下,氣-液-樹脂顆粒體系所需的NJSG及PmJSG均小于氣-液-玻璃微珠體系下,且當(dāng)表觀氣速較小時(shí)(Vs=0.0074 m·s-1),兩種體系下NJSG及PmJSG相差較大,隨著表觀氣速的增大(Vs=0.0152,0.0237 m·s-1),差異不斷縮小；樹脂顆粒作為固相時(shí),固含率對(duì)ΔNJSG/NJS的影響小于玻璃微珠作為固相時(shí),可忽略不計(jì)。2、通氣攪拌功率：顆粒特性(顆粒密度、顆粒粒徑分布等)對(duì)相對(duì)功率消耗的影響很小或沒有影響；樹脂顆粒作為固相時(shí),固含率和Flg對(duì)RPD的影響均更大；不同固體顆粒作為固相時(shí),Fr對(duì)RPD的影響差別不大。3、整體氣含率：在給定的VS和PTm條件下,氣-液-樹脂顆粒體系的氣含率均略大于氣-液-玻璃微珠體系的。利用實(shí)驗(yàn)數(shù)據(jù)擬合得出兩種顆粒三相體系中通氣功率,臨界懸浮特性及氣含率計(jì)算的關(guān)聯(lián)式,可為相似條件和槳型的三相攪拌反應(yīng)器工業(yè)設(shè)計(jì)提供參考。
[Abstract]:Agitation is a common operation in industrial production. Due to its strong applicability, it can be used in laboratory, chemical, metallurgical and pharmaceutical industries. In recent years, with the increasing size of agitator, the research on multi-layer impeller tank has become a hot spot. It has been shown that the radial flow propeller is the bottom propeller, and the axial flow propeller is the middle one. The upper propeller is more favorable for gas-liquid dispersion. In this paper, the combined propeller type PDT _ 2CBY (where the bottom propeller is the PDT propeller, that is, the parabolic disk turbine propeller with radial flow pattern), which is optimized by the former in the gas-liquid two-phase stirred tank with D / T = 0.33, is used in this paper. The CBY propeller with long and thin blade with axial flow in the upper two layers is used to study the gas-liquid dispersion and solid-liquid suspension performance in the gas-liquid-solid three-phase system. This study involves two different gas-liquid-solid three-phase systems. At first, the critical suspension characteristics of PDT 2CBY composite propeller were studied in the air-water-glass microsphere system (蟻 ~ (2 500km-3)). Aeration stirring power and overall gas holdup. The results show that the critical suspension characteristic of 1: 1: with the increase of apparent gas velocity vs and solid holdup CV, The critical suspension speed (NJSG) and critical suspension unit mass power (PmJSG) increased with the increase of aeration speed. The relative power demand (RPD) decreased with the increase of aeration rate and stirring speed. Under a certain stirring speed, the range of gas holdup with solid holdup CV is small, which is within 10%. The overall gas holdup increases with the increase of apparent gas velocity vs and unit mass power PTm, and the gas holdup increases with the increase of VS and PTm. The overall gas holdup in the stirred tank decreases with the increase of CV. A similar study was carried out in the air-water resin particle system (蟻: 1300kg m-3). The results show that the critical suspension characteristic of the cell is: at different apparent gas velocities, The NJSG and PmJSG of gas-liquid-resin granular system are lower than those of gas-liquid-glass microbeads system, and when the apparent gas velocity is smaller, the difference between NJSG and PmJSG is larger, and the difference between NJSG and PmJSG decreases with the increase of apparent gas velocity. When resin particles are used as solid phase, the effect of solid holdup on 螖 NJSG/NJS is smaller than that of glass beads as solid phase. The particle size distribution has little or no effect on the relative power consumption, and the solid holdup and Flg have more effect on RPD when the resin particles are used as solid phase. When different solid particles are used as solid phase, the effect of Fr on RPD is not significant. The overall gas holdup: under given vs and PTm conditions, The gas holdup of gas-liquid-resin particle system is slightly larger than that of gas-liquid-glass bead system. Using the experimental data, the correlations of ventilation power, critical suspension characteristics and gas holdup calculation in two kinds of granular three-phase systems are obtained. It can provide reference for the industrial design of three-phase stirred reactor with similar conditions and propeller type.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ027.2

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本文編號(hào)：1649448