基于化学改性的脱水污泥低温热风干化特性

我国每年污泥总产量逐渐增加,在其处理过程中普遍对含水率要求较高。采用热泵技术进行污泥低温干化,是一种既节能高效又不受地域限制的方法。但由于污泥的低温热干化特性尚不清楚,本文将通过在恒温恒湿箱中分别控制温度和污泥粒径两个单一变量,探究低温下二者对干化速率的影响,用曲线拟合得到直观的变化规律;并使用自主设计的立式污泥干化台架,对比探究铁-钙-碳基调理污泥在低温干化和传统干化下的水分释放特性。结果表明即使在60~80℃下,干化速率随温度升高仍然明显加快,干化时间缩短量与温度升高量满足递减的2次拟合多项式;而干化时间随污泥颗粒质量的变化满足递增的3次拟合多项式,所得拟合关系式适用于多种污泥;铁-钙-碳基调理剂可以显著提高污泥干化性能,稻壳和CaO会增加污泥孔隙和热导率,且稻壳在低温干化前期效果更明显。     

湿污泥低温热风干化特性及其数值模拟分析

污泥干化是其终端处置和资源化利用前必要的预处理环节。热风干化是湿污泥常用的处理技术，对污泥热风干化过程中传热传质特性进行深入研究，有助于相关干化工艺的研发并促进其工程化应用。依据自行设计的低温热风对流干化试验台，探究了污泥薄层干化过程中的传热传质规律，并分析了热风温度和流速对污泥干化过程中的湿分比、湿分迁移速率和内部平均温度的影响。此外，根据干化过程中污泥内部热量传递的能量方程，运用ANSYS Fluent软件模拟计算出污泥干化过程的特征参数。     

热重-红外联用分析制革污泥的燃烧特性

利用TG-FTIR对制革污泥的燃烧特性和燃烧过程气体释放情况进行了研究。研究发现,制革污泥挥发分和灰分含量较高,固定碳含量低、热值低。不同升温速率下,制革污泥的燃烧在800℃时已经比较充分,随着升温速率的增加,制革污泥碳燃烧的失重速率和峰值温度有所增加。运用Ozawa法进行活化能计算表明,制革污泥燃烧所需活化能随着反应程度的深入而增加。制革污泥的挥发分燃烧阶段符合三维扩散的Z-L-T方程反应模型,固定碳燃烧阶段符合自催化反应的P-T方程反应模型,且制革污泥在不同升温速率下燃烧动力学参数存在动力学补偿效应。TG-FTIR分析表明,不同升温速率对气体析出基本特征没有影响,在低温阶段,制革污泥的燃烧产物中有少量的有机酸组分析出。     

CaO作用下污泥的黏附-结团失效及干化特性研究

污泥的黏附和结团特性对干化过程有重要影响,研究开展了市政污泥和印染污泥在热力干化过程中的黏附-结团失效特性研究,深入探讨了CaO对污泥黏附-结团特性影响的规律,并分析了CaO对污泥干化速率及表观形态的影响。实验结果表明,在含水率≤85%时,污泥均表现出黏附失效特性。CaO能显著提高污泥表面黏附应力,但却能降低污泥在金属壁面的黏附量(含水率≤85%时)。此外,CaO能促进污泥干化速率的提升,并能抑制市政污泥在热力干化过程中裂纹的产生。     

动态传导式污泥干燥及冷凝液特性研究

搭建了污泥动态传导式干化装置,通过模拟污泥在间壁式干燥机中的运动状态,直观地记录干燥过程中污泥特性,并对不同温度下污泥特性曲线、残余固体的燃烧热值(Q)和挥发固分(VS)及冷凝液的有机物含量(TOC)进行分析。结果表明,温度对污泥干燥有促进作用,随着温度的升高,恒速阶段干燥速率增大,脱除水分减少。温度在125℃时,污泥干燥速率降低,干化处理缓慢,污泥处理量受限。在205℃以上高温区,干燥速率提升明显,污泥内脂肪类等有机成分及纤维素、木质素等不可降解物质因高温分解而释放,TOC浓度升高,固体挥发分减少,干污泥热值降低明显,不宜采用。综合考虑干燥效率和干化后污泥再利用,动态传导式污泥干燥的最佳区域应在145~185℃的恒速阶段。干燥冷凝水TOC浓度最小值为220 mg/L,属于高浓度有机废水,需处理后排放。污泥残余固份热值较高,可作为热源性物质加以利用。     

大尺度褐煤煤焦气化特性研究

煤层气化是将地下煤层进行有控制的燃烧来获取清洁燃气的技术。本文针对煤层气化过程的特点,利用自行设计的气化实验平台,研究气化剂流量、温度、原煤粒径对大尺度煤焦-水蒸气气化反应碳转化率和反应速率的影响。结果表明:在一定范围内,随水蒸气流量的增加,同一反应时间内煤焦碳转化率增加,气化反应速率也增大。原煤粒径对其气化反应性的影响显著,但无明显变化规律。随着气化温度的升高,煤焦固定碳达到相同碳转化率所需时间逐渐缩短。反应速率常数k随温度升高逐渐变大,反应级数随温度升高降低。实验结果为煤层气化现场实验工艺条件的优化提供了理论参考。     

活性污泥掺混水煤浆的成浆性能实验研究

将活性污泥(干基)以不同的比例与煤粉掺混,制备污泥水煤浆,研究污泥掺混量、添加剂用量、温度以及剪切速率对污泥水煤浆成浆特性的影响,并对掺混活性污泥煤浆进行流变特性和黏温特性分析研究。结果表明:污泥掺混量增加时,污泥水煤浆的最大成浆浓度有下降趋势,添加剂用量可提高污泥掺混水煤浆的整体性能;浆体温度在20℃~60℃时,水煤浆表观黏度降低,整体煤浆性能提升;掺混污泥水煤浆呈假塑性流体特征,污泥掺混量增大,浆体的假塑性特征变化并不明显;污泥添加量1%以下时,活性污泥加入对原煤黏温特性无影响。     

酞侧基聚芳醚酮拉伸屈服行为的研究

本文研究了酞侧基聚芳醚酮不同温度与不同形变速率下的拉伸屈服行为，发现屈服应力随温度升高而下降，随形变速率对数值的增大而增加，屈服应力对温度及形变速率的依赖性可用Ｅｙｒｉｎｇ理论来拟合，屈服能量随温度升高线性下降，从中可以求出屈服时所需热能与机械性能的比。杨氏模，屈服应变亦随温度升高而下降。     

CaO基的制备及温度对吸收率的影响

以石灰石和生料为原料,制备CaO吸收剂,用综合热重分析仪,研究温度对吸收剂吸收率的影响。结果显示,初始反应阶段,钙基吸收率在不同的温度下随反应时间都快速增加,温度升高时,钙基吸收率增加更快;产物层扩散控制阶段,温度750℃时,吸收率随反应时间延长基本没有变化,曲线趋于平缓,吸收反应速率很小,且不同温度下的样品吸收率变化趋势相同,都无太大增加。     

气氛和化学组成对高铁煤灰熔融特性的影响机理

采用灰熔点仪、XRD和热力学模拟,研究气氛和化学组成对高铁煤灰熔融特性的影响机理。研究结果表明,灰熔融温度随铁含量、钙含量或硅铝比增加而降低。弱还原气氛下低钙或低硅铝比煤灰熔融存在明显的初始熔融阶段,熔融过程遵循“软化-熔融”机理,而空气气氛下高钙或高硅铝比煤灰熔融过程属于“熔融-溶解”机理。弱还原气氛下铁含量增加显著促进石英和钙长石熔融,空气气氛下钙含量增加促进刚玉和石英熔融或转化为钙基硅铝盐。弱还原气氛下液相含量随硅铝比或铁含量增加而增加,液相黏度随钙含量或铁含量增加而降低,促进熔融传质;空气气氛下低钙或低硅铝比煤灰中铁存在于含铁固溶体,导致液相黏度高或液相含量低,熔融传质受阻。     

湿污泥颗粒的流化床干燥实验及模型

在鼓泡流化床内以河砂为干燥介质,对单颗粒湿污泥的流态化干燥特性进行实验研究,得到了流化床温度、污泥初始水分、污泥粒径及流化速度对干燥速率的影响规律：流化床温度及污泥粒径对干燥速率的影响都呈指数规律;污泥的水分越大,干燥速率越大;在鼓泡流化床流化速度达到2倍临界流化速度以上时,充分流化,流化速度再增大(2~5倍临界流化速度)对干燥速率没有明显影响. 在基本的扩散传质理论的基础上,利用实验数据回归得到湿污泥在鼓泡流化床内干燥的半经验模型,为流化床污泥干燥器的设计提供了基础数据和依据.     

酒精污泥在内热式振动流化床中的干燥特性研究

以干污泥颗粒为惰性粒子,采用内热式振动流化床对酒精污泥进行了干燥实验,考察了流化气速、进气温度、振动频率和内加热功率对污泥干燥特性的影响,分析了污泥湿含量和干燥速率的变化规律。结果表明,干燥速率随着流化气速、进气温度和内加热功率的增加而增加,随着振动频率增加呈先增长后降低的趋势。适度提高流化气速、进气温度、振动频率和内加热功率可以降低最终湿含量。将干燥过程分为降速I段和降速Ⅱ段,根据扩散传质理论,建立了内热式振动流化床中污泥干燥的数学模型,模型计算值和实测值的误差在20%以内,符合较好。实验结果为酒精污泥干燥过程的工业设计和操作提供了实验依据。     

城市污泥与木屑混合薄层干燥实验及动力学分析

角度研究了比,添加木通过对纯污泥和添加木屑的污泥进行薄层干燥对比实验,分别从混合比例、薄层厚度、干燥温度、风速木屑添加对污泥干燥特性的影响,并引入薄层模型对其干燥过程进行模拟。结果表明：与纯污泥干燥相屑后污泥干燥速率明显加快,且木屑添加比例越大、薄层越薄、干燥温度越高干燥速率越快,风速对干燥速率的影响不大;Wang—singh模型能很好的描述两种污泥薄层干燥,利用费克第二扩散定律导出的无限平板公式求出纯污泥和添加木屑的污泥在温度120℃～170℃时的有效扩散系数分别为6．13×10-6m／s～1．11×10-5m／s、1．07×10-5m／s～1．67×10-5m／s;由阿伦尼乌斯方程分别求得活化能为Es=16．67kJ／mol、Es=12．97kJ／mol。     

MVR空心桨叶干燥污泥的特性及动力学

基于空心桨叶干燥机建立了一套机械蒸汽再压缩式热泵干燥系统,将相同质量的污泥(100±0.1)kg,在真空压力约为95kPa、压缩机出口蒸汽温度为95~115℃进行恒温干燥实验,从而得到污泥干燥过程中含水率以及干燥速率等变化曲线,压缩机出口蒸汽温度为95~115℃,污泥临界湿含量从0.22增加到0.34。引入5种常用的污泥干燥模型,利用Origin软件对实验数据进行分段拟合分析,得到污泥加速阶段和降速阶段的干燥动力学模型MR=exp(-ktⁿ)。以分段函数形式表示的干燥方程分别为:MR=exp[-(2.78×10^-4T-0.01896)t^1.596],(加速阶段);MR=0.894-0.564(1.737×10^-4T-8.05×10^-3)t(恒速阶段);MR=exp[-(2.26×10^-4T-0.01365)t^1.984](降速阶段)。对实验得到的干燥模型进行验证,计算得到各干燥阶段污泥湿含量平均相对误差,并将实验所得干燥曲线和干燥速率曲线与模型计算值进行比较,可以看出分段处理能较好的描述污泥干燥规律。     

Experimental study on microwave drying of Chinese and Indonesian low-rank coals

Drying characteristics of low rank coals in a local microwave oven operating at 2.45 GHz were investigated. Effects of coal particle size, microwave power level, and coal sample size on drying characteristics were studied. Weight losses and temperature history of the samples were measured during drying. Drying rates were then obtained vs. drying time and moisture content. It was found that drying rate was increased with increasing coal particle size showing different trends from conventional drying methods reported in the literature. It was also observed that drying rate increased with increasing power output of the microwave oven or with decreasing coal sample weight. Effects of coal ash content and coal type were also investigated by comparing Chinese and Indonesian low rank coals. Ash content seems to be the governing factor in determining the drying characteristics for coal samples with small particle sizes. Drying mechanism of coals under microwave drying conditions was also discussed.     

Drying of water treatment process sludge in a fluidized bed dryer

The drying characteristics of water treatment process (WTP) sludge were investigated with a fluidized bed. The equilibrium moisture ratio of WTP sludge increased with relative humidity and decreased with temperature of drying air. However, equilibrium moisture ratio of WTP sludge was more sensitively dependent on relative humidity than temperature of drying air. When the sludge was dried in a batch fluidized bed, the drying rate of sludge decreased as the moisture ratio of sludge in the bed decreased. The periods of constant drying rates were apparently not observed on the drying rate curves. In addition, the maximum drying rates were increased with bed temperature and superficial air velocity. As the fluidized bed was operated continuously, the degree of drying of WTP sludge increased with bed temperature but was weakly dependent on superficial air velocity. However, the drying efficiency was decreased with bed temperature and relatively insensitive to superficial air velocity and increased with feed rate of sludge.     

污泥低温真空脱水干化成套技术的设计探讨

随着我国经济技术不断发展,污泥处置将从传统的卫生填埋向污泥干化焚烧或资源化利用方向发展。低温真空脱水干化成套设备采用低温真空干化原理,可以一次性将污泥的含水率从98%左右脱水干化至30%~40%,为后续的焚烧或资源化利用创造了条件。池州市前江工业园污水处理厂通过引进该项技术,实现了在一套设备内干化污泥的目的,出泥含水率小于40%。     

Adhesion and Cohesion Characteristics of Sewage Sludge During Drying

The stickiness of sludge during the drying process is an effect of its adhesion and cohesion. Furthermore, the adhesion and cohesion characteristics of sludge are comprehensive results of sludge components and their correlation with moisture. This work presents a simple method to test the adhesion and cohesion characteristics of sludge during the drying process based on the Jenike shear test. The results show that the most significant sludge adhesion and cohesion emerges at a moisture content of approximately 45 to 70% and 30 to 60%, respectively, and at a heating temperature of 120°C. An increase of the heating temperature to 200°C only brings a small movement to the sticky range location. The possible reasons for sludge adhesion and cohesion are discussed based on the results of sludge component analysis. The contributions of mineral materials with tiny particle sizes and metal salts to the adhesion and cohesion are discussed in this study because the contribution of organic matter has been widely demonstrated. The adhesion and cohesion nature of sludge exhibits a large effect on its drying characteristics. A remarkable fluctuation of both the drying rate and stirring power, located between the first and second falling rate period, is observed when the adhesion force of sludge reaches the maximum. When the sludge cohesion force decreases to approximately 3800 N/m², sludge bulks are broken with the stirring of paddles.     

Drying characteristics of particles using thermogravimetric analyzer

The drying characteristics (critical moisture content, equilibrium moisture content, constant drying rate and effective diffusivity) of various particles (gypsum, millet, polyvinyl chloride and silica gel) using a thermogravimetric analyzer were measured. The experiments were performed in the gas temperature range of 40 to 100 °C under isothermal conditions. The drying rate curve was mainly dependent on the moisture content, particle size, gas temperature and the internal structure of the solid particles. The equilibrium moisture content of solid particles decreased with increasing gas temperature, while the critical moisture content and the effective dispersion coefficient increased with increasing gas temperature. The effective diffusion coefficients of both PVC and gypsum particles were not able to be determined by Fick’s law since the experimental data were not well matched with the model predicted values, which consisted of the drying time in the falling-rate drying period.     

深度脱水污泥的热干化特性

深度脱水污泥中调理剂对其干化特性有着重要影响。实验采用4种典型复合调理剂对污泥进行预处理,制得脱水污泥,在N₂气氛、473 K条件下,探究调理剂对污泥干化过程中水分和污染物释放以及干化气、液、固产物特性的影响。结果表明,所用复合调理剂均可以有效降低脱水污泥含水率,加快干化阶段水分释放速率;调理过程中的酸碱及强氧化环境能破坏污泥中的有机结构,使污泥中的芳香族或噻吩S转化为更加稳定的磺酸或砜类S,且调理后的碱性环境让溶解的酸性含硫气体固定,从而使得干化时含硫气体释放量减少,但会加速氨气的释放。干化时复杂的气相产物溶解于冷凝液使其具有较高的pH以及COD并伴有恶臭,需进行进一步处理;污泥热干化后样品热值降低量在3.63%以内,不影响其能源化利用。