【摘要】：本文探索占地面積小、絮凝效果好的一種新型自保守混凝反應設備,通過數(shù)值模擬和絮凝沉降實驗考察不同流速和反應器結構對絮凝效果的影響,探索最優(yōu)的設備結構及最佳的水力學條件。首先,根據(jù)自保守混凝動力學理論,推導出螺旋導流裝置的結構參數(shù)計算方法。在此基礎上,計算G0為300-1,煤泥水濃度為40g/L,粒度為0.02mm時的絮凝反應器結構參數(shù),用于模擬和設計;同時放大螺旋外徑、改變流道長度以探討反應器結構對絮凝效果的影響。數(shù)值模擬結果表明:煤泥水沿螺旋導流裝置Z軸(豎直)方向,流體速度逐漸減小;由中心面上湍動能及有效能耗變化可知,較多的螺旋圈數(shù)和較大的入口流速對絮凝更有利;經(jīng)理論計算得到的速度梯度與模擬得到的速度梯度變化趨勢相同,均逐漸較小,但前者數(shù)值比后者大;同時也驗證了自保守絮凝沉降反應器設計的合理性。煤泥水絮凝沉降試驗結果表明:對于同一絮凝反應器而言,隨著初始流速的增加,溢流濁度呈現(xiàn)先下降,后上升的趨勢;而底流濃度則呈現(xiàn)先上升后下降的趨勢。因此存在最佳初始流速,初始流速過低或過高均對絮凝過程不利。由不同的絮凝反應器實驗結果對比可知,多螺旋大直徑的反應器絮凝沉降效果更好,最佳初始流速為0.151m/s。結合實驗結果與模擬分析結果可以得出:當反應器內(nèi)部體積加權湍動能在0.0068m2s-2~0.0027m2s-2之間,體積加權有效能耗在0.166m2s-3~0.042m2s-3之間時能有利于保證較好的絮凝效果。分段采樣的粒度分析結果表明:當初始流速均為0.151m/s時,對于同一反應器而言,絮體平均粒徑及分形維數(shù)隨著顆粒在螺旋流道中的流動而逐步增大,未出現(xiàn)明顯剪切破碎現(xiàn)象。在本文考察的反應器中,當結構參數(shù)為:外筒高度1500mm,外筒直徑100mm,內(nèi)筒直徑80mm時,絮體的分形維數(shù)最大,為2.1103,密實最好,沉降效果最佳。因此,依據(jù)自保守混凝動力學設計的絮凝沉降反應器能較好的滿足煤粒沉降過程的水力條件要求。
[Abstract]:In this paper, a new type of self-conserved coagulation reaction equipment with small area and good flocculation effect was explored. The effects of different flow rate and reactor structure on flocculation effect were investigated by numerical simulation and flocculation settlement experiment. To explore the optimal equipment structure and hydraulic conditions. Firstly, according to the theory of self-conservative coagulation dynamics, the calculation method of structural parameters of helical diversion device is derived. On this basis, the structural parameters of the flocculation reactor are calculated when G _ 0 is 300-1, slurry concentration is 40 g / L, particle size is 0.02mm, and the influence of reactor structure on flocculation efficiency is discussed by enlarging the outer diameter of screw and changing the length of flow channel. The numerical simulation results show that the velocity of coal slurry decreases gradually along the Z axis (vertical) direction of the helical diversion device, and from the change of turbulent kinetic energy and effective energy consumption on the center surface, it is found that more spiral circles and larger inlet velocity are more favorable for flocculation. The variation trend of velocity gradient obtained by theoretical calculation is the same as that obtained by simulation, which is gradually smaller, but the former value is larger than the latter, and the rationality of the design of self-conservative flocculation settling reactor is also verified. The results of flocculation settlement test show that for the same flocculation reactor, with the increase of initial flow rate, the turbidity of overflow decreases first and then increases, while the concentration of bottom flow increases first and then decreases. Therefore, there is an optimal initial flow rate, which is unfavorable to the flocculation process if the initial velocity is too low or too high. Compared with the experimental results of different flocculation reactors, the flocculation settling effect of multi-helix large diameter reactor is better, and the optimum initial velocity is 0.151 m / s. Combined with the experimental results and simulation results, it can be concluded that when the volume-weighted turbulent kinetic energy in the reactor is between 0.0068m2s-2~0.0027m2s-2 and the volume-weighted effective energy consumption in the range of 0.166m2s-3~0.042m2s-3, the better flocculation effect can be guaranteed. The results of particle size analysis show that when the initial flow rate is 0.151m/s, the average particle size and fractal dimension of the flocs increase gradually with the flow of particles in the spiral channel, and no obvious shear breakage occurs for the same reactor. In the reactor investigated in this paper, when the structural parameters are as follows: the height of the outer cylinder is 1500mm, the diameter of the outer cylinder is 100mm, and the diameter of the inner cylinder is 80mm, the fractal dimension of the floc is the largest, which is 2.1103, and the compactness is the best and the settlement effect is the best. Therefore, the flocculation settling reactor designed according to self-conserved coagulation kinetics can meet the hydraulic requirements of coal settling process.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD94

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