本文選題：水煤漿 + 粘度��； 參考：《中央民族大學》2017年碩士論文

【摘要】：漿體管道輸送技術(shù)由于其節(jié)能環(huán)保、低成本、無污染、作業(yè)不受天氣影響等優(yōu)勢成為了繼水運、公路、鐵路、空運之后的第五大運輸方式。在管道輸送中,如何在較小輸送阻力下達到最大的輸送效率以降低運行成本一直被普遍關(guān)注。固液兩相流的流變特性與管道輸送中流體的阻力特性密切相關(guān),是管道輸送系統(tǒng)參數(shù)設(shè)計和優(yōu)化的基礎(chǔ)依據(jù)。本研究將漿體和膏體作為一個有機整體,利用同心圓筒旋轉(zhuǎn)式流變儀,探究不同濃度、不同粒徑條件下水煤漿/膏的流變特性,并利用低場核磁共振技術(shù)檢測漿體中水分的橫向弛豫時間分布,區(qū)分和定量吸附水、間隙水和自由水,綜合分析漿體的微觀水分分布情況與宏觀流變特性變化結(jié)果,分析固液兩相流粘度變化的內(nèi)在微觀機理,從微觀機理角度分析并確定不同條件下水煤漿的漿體向膏體轉(zhuǎn)變臨界條件。主要工作和結(jié)論如下:(1)探究了不同濃度、不同粒徑條件下水煤漿的流變特性。隨著剪切速率的增加,水煤漿切應(yīng)力線性增加,符合賓漢塑性模型。水煤漿具有觸變性,隨著剪切速率的增加,表觀黏度減小。流變參數(shù)隨著濃度的增加而增加,變化趨勢呈指數(shù)型。且存在一個臨界濃度,在臨界濃度前后,流變參數(shù)變化率相差30倍,這是由顆粒間距的變化導(dǎo)致的。在一定濃度下,粘度隨著粒徑的增加而減小,原因是顆粒的理化性能和漿體中水分含量的變化。(2)利用低場核磁共振技術(shù)區(qū)分并定量水煤漿中的三種狀態(tài)水,分析了粒徑和濃度對不同狀態(tài)水分含量的影響。T2譜圖顯示三種水的加權(quán)平均弛豫時間存在1-2個數(shù)量級的差異。在一定粒徑下,吸附水含量與濃度無關(guān),.自由水和間隙水含量均隨濃度的增加而增多。在一定濃度下,吸附水和間隙水量與粒徑呈負相關(guān),自由水量與粒徑呈正相關(guān),原因是顆粒間距的大小和吸附團聚作用的強弱。(3)分析了漿體中微觀水分分布與宏觀流變特性之間的相互作用關(guān)系,進一步從理論角度確定了漿體向膏體轉(zhuǎn)變的臨界條件。漿體中自由水含量的變化是決定其宏觀流變特性的根本原因。提出了可以同時考慮顆粒間距、自由水含量及顆粒粒徑大小等多因素的參數(shù),即顆粒間距比L/d。0.05L/d0.10為不同濃度、不同粒徑物料漿體向膏體轉(zhuǎn)變的臨界條件。通過數(shù)據(jù)擬合得到了不同粒徑水煤漿物料漿體向膏體轉(zhuǎn)變的臨界濃度公式,為最佳輸送條件的確定提供依據(jù)。
[Abstract]:Slurry pipeline transportation technology has become the fifth mode of transportation after waterway, road, railway and air transportation because of its advantages of energy saving, environmental protection, low cost, no pollution and operation without weather influence. In pipeline transportation, how to achieve the maximum transport efficiency and reduce the operation cost under the small transportation resistance has been widely concerned. The rheological characteristics of solid-liquid two-phase flow are closely related to the resistance characteristics of the fluid in pipeline transportation, which is the basis for the parameter design and optimization of pipeline transportation system. In this study, slurry and paste as an organic whole, using concentric cylinder rotary rheometer, the rheological characteristics of coal water slurry / paste under different concentration and different particle size were studied. The transverse relaxation time distribution of water in slurry was measured by low field nuclear magnetic resonance (LNMR) technique, and the absorption water, interstitial water and free water were distinguished and quantified. The microcosmic water distribution and the change of macroscopic rheological characteristics of slurry were analyzed synthetically. The internal microscopic mechanism of viscosity change of solid-liquid two-phase flow is analyzed and the critical conditions of slurry to paste transformation under different conditions are analyzed and determined from the angle of microscopic mechanism. The main work and conclusion are as follows: 1) the rheological characteristics of coal water slurry with different concentration and particle size are studied. With the increase of shear rate, the shear stress of coal water slurry increases linearly, which accords with the Bingham plastic model. Coal water slurry has thixotropy and the apparent viscosity decreases with the increase of shear rate. The rheological parameters increased with the increase of concentration, and the change trend was exponential. There is a critical concentration, and the change rate of rheological parameters varies by 30 times before and after the critical concentration, which is caused by the change of particle spacing. At a certain concentration, the viscosity decreases with the increase of particle size, because the physicochemical properties of the particles and the change of water content in the slurry. 2) the low field nuclear magnetic resonance technique is used to distinguish and quantify the three states of water in the coal water slurry. The effects of particle size and concentration on water content in different states were analyzed. T2 spectra showed that there were 1-2 orders of magnitude difference in the weighted mean relaxation time of the three kinds of water. Under certain particle size, the content of adsorbed water has nothing to do with the concentration. The contents of free water and interstitial water increased with the increase of concentration. At a certain concentration, adsorbed water and gap water were negatively correlated with particle size, and free water was positively correlated with particle size. The reason is that the size of particle spacing and the strength of adsorption and agglomeration are used to analyze the interaction between microscopic water distribution and macroscopic rheological properties in the slurry, and the critical conditions for the transition from slurry to paste are determined theoretically. The change of free water content in slurry is the fundamental reason for its macroscopic rheological characteristics. The parameters such as particle spacing, free water content and particle size can be considered at the same time, that is, the critical conditions for the transition from slurry to paste with different particle spacing ratio (L/d.0.05L/d0.10). The critical concentration formula for the transformation of coal water slurry with different particle sizes into paste is obtained by fitting the data, which provides the basis for determining the optimal transportation conditions.
【學位授予單位】：中央民族大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U171

【參考文獻】

相關(guān)期刊論文 前10條

1 陳磊;趙健;趙明;;粉煤灰粒徑對高濃度膠結(jié)充填材料性能的影響研究[J];煤炭工程;2017年02期

2 郝華東;李寒旭;段錦;趙東升;鄧業(yè)新;;摻配煤泥對水煤漿性能影響因素的研究[J];煤炭技術(shù);2017年02期

3 李帥;王新民;張欽禮;王石;;超細全尾砂似膏體長距離自流輸送的時變特性[J];東北大學學報(自然科學版);2016年07期

4 吳愛祥;周靚;尹升華;王雷鳴;;全尾砂絮凝沉降的影響因素[J];中國有色金屬學報;2016年02期

5 張修香;喬登攀;;廢石-尾砂高濃度料漿的流變特性及屈服應(yīng)力預(yù)測模型[J];安全與環(huán)境學報;2015年04期

6 任海鋒;白賢武;程光華;盛學棟;陶海東;;分級尾砂料漿輸送性能及流變特性試驗研究[J];有色金屬(礦山部分);2015年04期

7 陳光國;;我國長距離漿體管道輸送系統(tǒng)的應(yīng)用概況與展望[J];金屬礦山;2015年05期

8 吳愛祥;劉曉輝;王洪江;焦華U，

本文編號：1981011