新型厌氧反应器水力与水质模拟和结构优化
VIP免费
摘 要
在研究高温厌氧工艺时，研究人员发现上流式厌氧污泥床（up-flow anaerobic
sludge bed，简称 UASB）反应器在高负荷运行时高产气量会导致污泥的流失，针
对UASB 工艺这个缺陷，van Lier 在UASB 工艺的基础上提出了上流式分段污泥
床（up-flow Staged Sludge Bed 简称 USSB）， 它是在厌氧反应器内竖向设置多个挡
板，将反应器分成多段区室，同时起到气固分离的作用，从而使每一段区室都能
进行排气，实现气液固三相分离，同时避免中间产物的积累，从而避免高浓度乙
酸对污泥活性的影响，保持出水的 VFA 在较低浓度（<200mgCOD/L）。
上流式分段污泥床（up-flow staged sludged bed 简称 USSB）反应器内部存在
的生化反应过程和流体流动过程都极其复杂。因此，对于厌氧反应器内的流体动
力学与生化动力学有比较清晰的认识是比较困难的。本课题对 van Lier 提出的
USSB 反应器进行水力和水质的双重研究。反应器结构的水力学研究主要包括反应
器底部的进水方式和内部挡板的结构形式对反应器内部流场流态的影响，研究的
进水方式包括间隙进水、局部进水和均匀进水三种方式，而挡板的结构形式主要
考虑其与墙面形成的回流缝的宽度变化形成不同倾角。采用不同尺寸的底部截面
进水模拟间隙进水（10mm×100mm）、局部进水（50mm×100mm）和均匀进水
（150mm×100mm），而回流缝的宽度选取 50mm 和20mm。通过反应器的水力学
数值模拟计算结果，分析不同结构形式的反应器内部流场情况，，获得流态较好的
结构形式；并进一步对优化结构的反应器分段排气后的气液分离效果和进水流速
对污泥床膨胀和流化作用的影响进行模拟研究。其次，在水力学模拟研究的基础
上，对反应器内的生化反应同时进行考察，即建立水力学模型与生化动力学模型
的耦合模型，模拟和分析污水中各组分污染物的分布。论文主要研究工作内容如
下：
（1）通过三种不同的进水截面形式和不同距离的挡板回流缝宽度组成六种结
构形式，采用计算流体动力学（Fluid Dynamics，简称 CFD）软件 Fluent 对着六种
结构形式的 USSB 反应器进行数值模拟，数值模拟计算结果表明：底部采用局部
进水形式（截面尺寸 50mm×100mm），挡板回流缝较宽（缝隙宽 50mm）时，反
应器内的流场分布比较符合 Lettinga 教授提出的阶段式多相厌氧消化系统的思想，
即反应器内形成局部完全混合而整体推流的形式。
（2）在上述模拟结果的基础上，进行气液两相流和气液固三相流模拟。气液
两相流模拟时，对每一段区室的气液交界面设置为 Degassing 边界条件，即气体可
以自由逸出，模拟结果表明：每一段排气是反应器获得较好的气液分离效果。庵
后通过气液固三相流模拟考察不同流速下固相分布和污泥床流化情况。模拟计算
结果表明：当水力上升流速 v=0.001m/s（3.6m/s）时，不但可以使污泥床层保持较
好的浮动情况，而且可以在污泥床层上部形成颗粒污泥的悬浮区域，使颗粒污泥
均匀分布于反应器内，达到反应器内废水与颗粒污泥的充分接触和混合，增强反
应器的处理效果。
（3）为了考察水力学和生化反应的综合影响，本文还进行了水力学模型与生
化模型的耦合研究，通过对 ADM1 号模型分析找到其与 Fluent 软件的接入点，即
模型组分的反应速率方程相当于 Fluent 中的源项，并对源项的组分进行建模。采
用耦合模型对部分酸化废水进行模拟计算，将耦合模拟的结果与 van Lier 的试验结
果比较分析，表明该耦合模型能一定程度上模拟和预测 USSB 反应器处理部分酸
化废水（蔗糖+VFA 组成的废水）的情况。
本文的研究结论可以更好的认识 USSB 反应器内部流场和污染物质的降解分
布情况，为进一步优化和应用 USSB 反应器的研究提供参考依据和理论基础。
关键词：上流式分段污泥床 计算流体动力学 数值模拟 耦合模型
ABSTRACT
In the research of thermophilic anaerobic digestion process, the researchers found
that the high production of UASB, which operated at high organic load, will result in
loss of sludge. To enhance the stability of thermophilic treatment, a staged digestion
process in a device denominated as the upflow staged sludged bed (USSB) reactor,
developed on the basis of the upflow anaerobic sludge bed (UASB), was applied by van
Lier to treat acidified and partially acidified wastewater. Several multiple baffles, which
were used as the gas-solid separator, were set up on the vertical in the reactor, and the
reactor was composed of various compartments, so that each compartment can exhaust
and avoid the accumulation of intermediateas, which lead to low concentration
（<200mgCOD/L）of volatile fatty acids (VFA) in the effluent.
A variety of biochemical reactions occurred in USSB reactor, at the same time, the
flow of fluid is extremely complex the reactor. Therefore, it is quite difficult to have a
good knowedge of fluid dynamics and biochemical kinetics of anaerobic in the reactor.
Hydraulics and kinetics of USSB reactor were both studied by means of Fluent software.
First of all, through the hydraulics simulation of the reactor, the inner flow field of
different structures, include influent modes and the baffle, of reactors were studied.
Different sizes of bottom section which present the influent modes were applied.The
influence of degassing in each compartment on gas-liquid separation, and of inlet
velocity on expansion and fluided of sludge bed were studied. Secondly, on the basis of
hydraulics simulation studies, biochemical kinetic model coupled with hydraulics model
were simulated. The distribution of of various components in sewage was studiedd
according to the simulated results.
Three different size of bottom section and two different distances between baffle
with wall form six types of reactor structure, which were simulated by computational
Fluid Dynamics (CFD) technique. The numerical simulation results show that the
structure of the size（50mm×100mm） of inlet section and the distance (50mm)
between baffle with wall, the inner flow field distribution in the reactor is in accordance
with the theory of staged multi-phase anaerobic system (SMPA), proposed by professor
Lettinga local, which completely mixed flow partial and plug flow on the whole.
Simulation of gas-liquid two phase flow and gas-liquid-solid three phase flow were
performed according to the simulation results above.The interface of gas-liquid in each
compartment was set as the Degassing boundary condition in the simulation of
gas-liquid two phase flow, so that the gas can escape.The simulation results show that
degassing in each compartment obtains a good separation effect of gas-liquid. To study
the influence of up-flow velocity on volume fractiom distribution of solid-phase and
fluidized of sludge bed, gas-liquid-solid three phase flow was simulated. Simulation
results show that when the up-flow velocity is 0.001 m/s, the sludge bed can not only
keep floating, but also can form suspended granular sludge on the upper area, which can
make the granular sludge distribute evenly over the reactor, and achieve a well mixure
between wastewater with granular sludge in reactor, and also enhance the processing
effect of the reactor.
To study the comprehensive influence of hydraulics and biochemical reaction, the
hydraulics model and biochemical kinetic model were coupled, the similarity of ADM1
model and Fluent software was analyzed, which the reaction rate equation of the model
components is equivalent to the source in the Fluent software, and the components in
ADM model was transformed into the source term in Fluent. Compare simulation
results with experiment results by van Lier, to a certain extent, the coupling model can
simulate and predict treatment of partial acidified wastewater (sucrose+VFA wastewater)
by USSB reactor.
The conclusion of this paper can help get a better idea of inner flow field and the
degradation and distribution of the pollutants in USSB reactor, meanwhile provide the
reference for further optimization and application of USSB reactor.
Key Wrod: USSB, SMPA, CFD, Fluent, coupling model
目 录
中文摘要
ABSTRACT
摘 要 .............................................................. 6
ABSTRACT ............................................................ 8
目 录 .............................................................. 10
第一章 绪 论 ........................................................ 1
1.1 引言 ........................................................... 1
1.2 厌氧反应器的发展 .............................................. 2
1.2.1 废水厌氧处理的机理 ........................................ 2
1.2.2 厌氧反应器的发展 .......................................... 3
1.2.3 上流式分段污泥床反应器的提出和研究概况 .................... 5
1.3 厌氧消化模型及其在水处理中的应用 .............................. 7
1.3.1 厌氧消化模型概述 .......................................................................................... 7
1.3.2 厌氧消化模型在水处理中的应用 ................................................................. 8
1.4 水力模型与生化模型的耦合研究 .................................. 9
1.5 课题研究内容和意义 ............................................ 9
1.5.1 课题研究的主要内容 ...................................................................................... 9
1.5.2 课题研究的目的和意义 ............................................................................... 10
第二章 计算流体动力学技术及其应用 .................................. 11
2.1 CFD 的基本概述 ................................................ 11
2.1.1 CFD 的简介 ..................................................................................................... 11
2.1.2 CFD 中基本流体力学概念和性质 ................................................................ 11
2.2 CFD 模拟软件及其构成 .......................................... 15
2.3 CFD 的求解过程 ................................................ 15
2.3.1 建立数学模型 ................................................................................................ 15
2.3.2 确定数值解法 ................................................................................................ 16
2.3.3 模型的运行计算 ............................................................................................ 16
2.3.4 计算结果的输出和处理 ............................................................................... 16
2.4 CFD 技术的应用 ................................................ 17
2.4.1 CFD 技术在水处理中的应用 .................................. 17
2.4.2 CFD 技术在厌氧反应器中的应用 .............................. 17
2.5 Fluent 软件及其在水处理中的应用 ............................... 19
2.5.1 Fluent 软件简介 ........................................................................................... 19
2.5.2 Fluent 软件在水处理中的应用 .................................................................. 20
第三章 USSB 反应器数值模拟的模型与方法 .............................. 22
3.1 模型的建立 ................................................... 22
3.2 数值解法和离散格式 ........................................... 25
3.3 多相流模型 ................................................... 27
3.3.1 多相流模型介绍 ............................................................................................ 27
3.3.2 多相流模型的选择和设置 ........................................................................... 28
3.4 湍流模型 ..................................................... 28
3.5 边界条件 ..................................................... 30
3.6 数值计算方法 ................................................. 31
3.7 本章小结 ..................................................... 33
第四章 USSB 反应器的多相流模拟 ...................................... 34
4.1 多相流模拟过程 ............................................... 34
4.1.1 几何模型 ........................................................................................................ 34
4.1.2 数值模拟计算设置 ........................................................................................ 35
4.2 气液两相流模拟结果与分析 ..................................... 37
4.2.1 液相速度场分布 ............................................................................................ 37
4.2.2 气相体积分布 ................................................................................................ 42
4.3 气液固三相流模拟结果与分析 ................................... 44
4.3.1 不同进口流速液相流场分布 ....................................................................... 44
4.3.2 不同进口流速固相体积分数 ....................................................................... 46
4.4 本章小结 ..................................................... 49
第五章 水力学模型与厌氧消化模型耦合研究 ............................ 50
5.1 耦合模拟的实施依据 ........................................... 50
5.1.1 耦合的理论基础 ............................................................................................ 50
5.1.2 耦合的实施依据 ............................................................................................ 51
5.2 模型入流组分物质的确定和建模 ................................. 52
5.3 耦合模型的构建 ............................................... 54
5.4 模拟结果分析 ................................................. 55
相关推荐
作者：侯斌
分类：高等教育资料
价格：15积分
属性：75 页
大小：3.34MB
格式：PDF
时间：2025-01-09
