本文選題：A2MO-M工藝 + 計算流體力學��； 參考：《哈爾濱工業(yè)大學》2015年碩士論文

【摘要】：強化污水處理及原位污泥減量工藝系統(tǒng)(簡稱A2MO-M工藝),是一個新穎的同步污水處理和污泥減量的結(jié)合反應器,旨在同時減少剩余污泥和去處廢水中的營養(yǎng)物質(zhì)。A2MO-M反應器主要是通過分級曝氣池的梯度溶解氧條件和污泥停留池的微氧條件培養(yǎng)更為豐富的微生物種類,達到強化水處理以及原位污泥減量的作用。因此,對A2MO-M反應器內(nèi)部進行流體力學研究,優(yōu)化反應器內(nèi)部的流態(tài),能提高A2MO-M反應器的性能。本文采用計算流體力學對A2MO-M工藝中兩個重要的生物反應池——分級曝氣池以及微氧污泥停留池,進行了流場特性的模擬研究。對原有分級曝氣池模擬結(jié)果進行分析,發(fā)現(xiàn)其在單池室池形、微氧池室攪拌槳布設(shè)以及好氧池室曝氣方案上存在流體力學設(shè)計缺陷。通過對單池室的改進方案進行模擬,獲得了分級曝氣池的優(yōu)化方案。結(jié)果表明:分級曝氣池中單池室的長寬比對整體流場有較大的影響。對2:1、3:2和1:1三種長寬比進行模擬,得出了長寬比為1:1時混合液相平均流速較大,并且能獲得較為均勻的流速分布。微氧池室以攪拌為主要的混合方式,分別模擬了槳葉與池底距離為10cm、7.5cm和5cm的三種情況。其中,槳葉與池底距離為5cm時池體上端平均流速下降量較小,氣相能充分與液相混合,有利于保持均勻微氧條件�？s小了好氧池室曝氣裝置的尺寸,增加了曝氣位點,并考慮了兩種均勻排布以及一種近壁排布對池室內(nèi)混合液相流態(tài)的影響。在有效曝氣面積相同的情況下,減小曝氣裝置尺寸、增加位點,有利于池室內(nèi)產(chǎn)生均勻流場。4-4近壁排布具有較佳的池內(nèi)平均速率,在曝氣位點之間留下了充足的空間,使液相可以向下流動,有利于反應器內(nèi)液相形成循環(huán)流場。對原有微氧污泥停留池進行了停留時間分布試驗,并采用CFD對RTD試驗進行模擬。獲得了污泥停留池內(nèi)水力特征,驗證了CFD模型模擬結(jié)果的有效性。結(jié)果表明,RTD實驗計算得到平均停留時間僅為420min,停滯區(qū)占總區(qū)域的22.22%,對其進行流體力學研究的具有必要性;CFD模型能較好的模擬污泥停留池內(nèi)流態(tài),模擬結(jié)果與實驗結(jié)果最大誤差為14.7%,平均誤差為7.8%。對四種攪拌槳類型進行比較,雙層槳葉互相壓縮軸向循環(huán)區(qū)域的高度,形成渦旋,不利于混合和傳質(zhì);斜葉槳能有效的在旋轉(zhuǎn)區(qū)域形成向下的軸向流動,有利于氧氣的傳質(zhì),氣相分散效果較好。因此,斜葉單槳為最優(yōu)選擇。對比不同槳葉數(shù)對流場的影響。隨著槳葉葉片數(shù)量的增加,混合液相軸向和徑向平均速率略有下降,氣體分布結(jié)果與徑向平均速率結(jié)果相符合。在相同混合液相總平均速率的情況下,槳葉數(shù)的增加能減小轉(zhuǎn)速,有效降低中心攪拌區(qū)域的流速,使得整體流速分布更為均勻。綜合考慮,四斜葉槳為微氧污泥停留池較優(yōu)選擇。
[Abstract]:The enhanced sewage treatment and in-situ sludge reduction process system (A2MO-M process) is a novel combined reactor for simultaneous sewage treatment and sludge reduction. In order to reduce the nutrient in excess sludge and wastewater simultaneously. A2MO-M reactor is mainly through the gradient dissolved oxygen condition of the staged aeration tank and the micro-oxygen condition of the sludge retention tank to cultivate more abundant microbial species. To enhance water treatment and sludge reduction in situ. Therefore, the performance of A2MO-M reactor can be improved by studying the internal hydrodynamics of A2MO-M reactor and optimizing the flow state of A2MO-M reactor. In this paper, computational fluid dynamics (CFD) was used to simulate the flow field characteristics of two important biological reaction tanks in the A2MO-M process, namely, the two-stage aeration tank and the micro-oxygen sludge retention tank. By analyzing the simulation results of the original staged aeration tank, it is found that there are some defects in the hydrodynamic design of the single cell, the micro-oxygen tank, and the aeration scheme of the aerobic tank. By simulating the improved scheme of single cell, the optimization scheme of staged aeration tank is obtained. The results show that the aspect ratio of a single cell in a staged aeration tank has a great influence on the overall flow field. Three aspect ratios of 2: 1: 3: 2 and 1:1 are simulated. The results show that the average velocity of liquid mixture is larger and more uniform velocity distribution can be obtained when the aspect ratio is 1:1. In the chamber of the micro-oxygen tank, mixing is the main mixing mode, and the three conditions of blade to bottom distance of 10 cm to 7.5 cm and 5cm to the bottom are simulated, respectively. When the distance between the blade and the bottom is 5cm, the average velocity of the upper end of the tank decreases less, and the gas phase energy is fully mixed with the liquid phase, which is favorable to maintain the homogeneous oxygen condition. The size of aeration unit in aerobic tank was reduced and the aeration site was increased. The effects of two kinds of uniform arrangement and one kind of near-wall arrangement on the mixed liquid phase flow in the chamber were taken into account. Under the condition of the same effective aeration area, reducing the size of aeration device and increasing the number of sites is beneficial to the uniform flow field. 4-4 near wall arrangement has a better average velocity in the pool, leaving enough space between the aeration sites. The liquid phase can flow downwards, which is beneficial to the formation of circulating flow field in the reactor. The residence time distribution test of the existing micro-oxygen sludge retention tank was carried out, and the RTD test was simulated by CFD. The hydraulic characteristics of sludge retention tank are obtained, and the validity of CFD model simulation results is verified. The results show that the average residence time is only 420 min, and the stagnant area accounts for 22.22 min. The CFD model is necessary to study the hydrodynamics. The maximum error between the simulation results and the experimental results is 14.7 and the average error is 7.8. Compared with the four types of impeller, the double-layer blade compresses the height of axial circulation region, forming vortex, which is not conducive to mixing and mass transfer, and inclined blade propeller can effectively form downward axial flow in the rotating region, which is beneficial to the mass transfer of oxygen. The effect of gas phase dispersion is better. Therefore, the single propeller with oblique blade is the best choice. The effects of different blade numbers on the flow field are compared. With the increase of blade number, the axial and radial average rates of mixed liquid phase decrease slightly, and the gas distribution results are in agreement with the radial average rate results. In the case of the same average liquid phase velocity, the increase of blade number can reduce the speed of the rotor, reduce the velocity in the center mixing area, and make the overall velocity distribution more uniform. Considering synthetically, the four tilted blade paddle is the best choice for micro-oxygen sludge retention tank.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X703.3

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本文編號：2106965