CAS OpenIR
烹饪油烟的高效分离、吸收-催化及快速检测技术探究
李文辉
Thesis Advisor陈运法
2018-07
Degree Grantor中国科学院研究生院
Degree Name博士
Degree Discipline材料学
Keyword烹饪油烟,分离,吸收,催化,传感
Abstract

烹饪油烟已成为我国大气污染的重要来源,也对人体健康产生极大危害,因此,油烟废气净化治理不容忽视。中国特色的高温烹饪,使得油烟废气成分复杂,包括了气、液、固三相。油烟污染问题在餐饮企业尤为突出,其治理难度大。然而,对于餐饮企业所排放的油烟,目前采用的净化技术形式单一、效率低下,很难达到理想效果。因此,根据餐饮企业油烟废气复杂性的特点,分阶段对其净化治理显得尤为重要。本论文旨在通过技术上的创新,从装置设计和材料制备角度出发,构建分级油烟净化治理技术框架。此外,还尝试将气敏传感技术引入油烟净化系统,通过气敏传感技术与分级油烟净化技术相结合,构建智能油烟净化模式。本论文的主要研究内容和结果如下:1.油脂分离旋转滤网的设计与应用(1)设计了单层油脂分离旋转滤网,并应用于实验室自行搭建的油脂分离测试系统。通过改变滤网的转速和孔径,考察旋转滤网对油脂分离度和颗粒物的截留情况。结果表明,对于同一孔径的滤网,油脂分离度随着转速的增大而增大,且对PM10、PM2.5、PM1和PM0.1均有明显的去除效果;在高转速下,减小滤网孔径可有效增加滤网与颗粒物的物理碰撞几率,从而增加整机油脂分离度和细颗粒物的拦截效果,当转速为1300 r/min,滤网孔径为0.73 mm(24目)时,整机油脂分离度达96.5%。此外,粘附于滤网上的油脂颗粒物在离心力作用下可向外甩出,保持滤网清洁,不堵塞。(2)利用Fluent软件对旋转滤网式油烟机的油气两相流动进行数值模拟,观察油脂颗粒物在滤网的运动状态。模拟结果表明,旋转滤网能有效地截留油脂颗粒物,但同时也存在导致油烟二次逃逸的死角位置。因此,可利用模拟结果对油烟机进行优化改造。(3)通过齿轮间的两两配合,设计了双层同轴异向油脂分离旋转滤网。双层滤网结构有效地增加了油脂颗粒物与滤网的物理碰撞几率,且使得油脂颗粒物在正、反漩涡中停留时间变长而将其有效截留。此外,通过在滤网上增加带导油槽结构辐条和将滤网倾斜,以利于粘附在滤网上的油脂颗粒物向外甩出,从而保持滤网清洁,不堵塞。2.超重力旋转填充床强化VOCs吸收及类芬顿催化降解有机废液(1)设计了并流式超重力旋转填充床,以次氯酸钠(NaClO)和十二烷基苯磺酸钠(SDBS)溶液为吸收液,处理二甲苯有机气体。考察不同参数对二甲苯去除率和气相总传质系数的影响,以此评价该技术对有机气体的吸收能力。结果表明,二甲苯去除率与pH值和气体流量成反比关系,与液体流量、NaClO浓度和转速成正比关系,添加表面活性剂SDBS能有效增大旋转填充床对二甲苯的去除效率。此外,利用实验数据拟合气相总传质系数关联式,其计算值与实验值的偏差在±30%之间,二者较好地吻合。(2)以铁基金属有机骨架化合物为前驱物,通过两步煅烧法合成磁性多孔Fe3O4/C八面体类芬顿催化剂,并应用于有机废液的降解。该材料表现了优越的类芬顿催化性能和良好的循环稳定性,这归因于石墨化碳层的存在,并通过自牺牲作用而保护Fe3O4内核的活性位点(≡Fe2+)免受氧化。此外,介孔结构也有利于固-液接触和表面电子转移、传输,从而进一步提高催化性能。3.氧化锌基半导体气敏传感材料的制备与应用(1)以锌基金属有机骨架化合物为前驱物,直接煅烧合成ZnO空心纳米笼气敏传感材料,并应用于低浓度VOCs的检测。该结构具有的介/大孔通道有利于有机气体分子的吸附-脱附,也有利于充分暴露活性位点和氧空位,从而离子化表面吸附氧为活性氧物种,并提高低浓度VOCs的检测灵敏度。结果表明,ZnO空心纳米笼对0.1 ppm苯气体的灵敏度为2.3 ppm-1,对50 ppb丙酮气体的灵敏度为15.3 ppm-1。(2)以锌-铁基金属有机骨架化合物为前驱物,直接煅烧合成ZnO/ZnFe2O4空心异质结气敏传感材料。该材料对还原性VOCs气体表现了反常的n-p-n半导体传导率转变现象。这是由于异质界面的存在,使得不同工作温度下界面处电子-空穴发生此消彼长过程,费米能下移或上移而造成的。该反常的传导率转变现象显著提高气敏传感器的选择性。;Cooking oil fumes has become an important precursor of the air pollution in China, and a danger source to the human health. Thus, it is an urgent work to purify and control the cooking oil fumes. The high temperature cooking with Chinese characteristics makes the fumes with complex composition, including gas, liquid and solid. Especially, the cooking oil fumes pollution is tremendously serous in catering enterprises. At present, it is hard to achieve the desired effect with a single purification technology. Therefore, multiple purification technology and devices should thus be developed to treat with the cooking oil fumes. This dissertation aims to construct a purification treatment system of cooking oil fumes from the perspective of device design and material synthesis through technological innovation. Moreover, it is also trying to introduce gas sensing technology into the oil fumes purification system, and develop an intelligent purification mode of cooking oil fumes. The detail content and results were listed below.1. Design and application of a rotary grease separating filter(1) A monolayer rotary grease separating filter was desinged, and used for the separation of grease particulate matter in a home-made grease separation test system. Two important variables of pore diameter and rotate speed were investigated on grease separation and particulate matter interception. The results showed that grease separation was increased with the increase of rotate speed under the same pore diameter filter, and a high rotate speed was favor of the removal of PM10, PM2.5, PM1 and PM0.1. Moreover, reducing the bore diameter of the filter effectively increased the probability of physical collision between filter and particulate matter under a high rotate speed, and thus enhanced the grease separation and particulate matter interception. Significantly, the grease separation reached 96.5% with 1300 r/min rotate speed and 0.73 mm pore diameter. In addition, the grease particulate matter attached on the filter can easily be thrown out by centrifugal force, and thus keeping the filter clean and not blocked.(2) Numerical simulation of the oil and gas flow was carried out in a range hood with the rotary filter, and to observe the motion state of grease particulate matter. The simulation results showed that rotary filter effectively intercept the grease particulate matter, but a dead angle existed and caused the secondary escape of grease particulate matter. Therefore, the simulation results can be used to optimize the range hood.(3) A coaxial-heterodromous double layer rotary grease separating filter was designed through the cooperation of two pairs of gears. The filter with double layer structure further increased the probability of physical collision between filter and particulate matter, and made the particulate matter stay longer in the positive and negative airflow vortex, thus effectively intercepting the particulate matter. Moreover, by adding the spoke with oil groove structure into the filter and tilting the filter, the grease particulate matter attached on the filter can more easily be thrown out, and thus keeping the filter clean.2. Intensification of VOCs absorption by a co-current rotating packed bed and degradation of organic wastewater by Fenton-like catalysis(1) A co-current rotating packed bed was designed and applied for the removal of volatile organic compounds (VOCs) by sodium hypochlorite and sodium dodecyl benzene sulfonate from air stream. Xylene was used as the model VOC. The effect of different variables on xylene removal efficiency and overall mass transfer coefficient were investigated, and the obtained results were used to evaluate the treatment ability of the co-current rotating packed bed. The results showed that the xylene removal efficiency was increased with the decrease of pH and gas flow rate, and increased with the increase of liquid flow rate, NaClO concentration and rotational speed. In addition, the surfactant of SDBS effectively increased the removal efficiency. Moreover, a correlation for overall mass transfer coefficient of the co-current rotating packed bed was proposed by fitting the experimental data, which was in good agreement with the experimental data (the deviation≤±30%).(2) Magnetic porous Fe3O4/carbon octahedra were constructed by a two-step controlled calcination of iron-based metal organic framework. Significantly, the porous Fe3O4/carbon octahedra showed efficiently heterogeneous Fenton-like reactions and good recyclability for decomposing the organics in wastewater. The good Fenton-like catalytic performance of the as-synthesized Fe3O4/carbon octahedra was ascribed to the unique mesoporous structure derived from MOF-framework, as well as the sacrificial role and stabilizing effect of graphitic carbon layer for preventing ≡Fe2+ from oxidation. Moreover, the mesoporous structure was favor of the electron transfer, further enhancing the Fenton-like performance.3. Synthesis and application of ZnO-based gas sensing materials(1) Hierarchical hollow ZnO nanocages were synthesized by a facile strategy through the simple and direct pyrolysis of Zn-based metal-organic framework. The obtained hollow structure processed meso-/macro-porous channels and facilitated the diffusion and surface reaction of gas molecules. Moreover, the porous hollow structure was favor of the exposure of active sites and oxygen vacancies, thus enhancing the sensitivity of low-concentration VOCs. The results showed that the ZnO hollow nanocages perform sub-ppm level sensitivity with 2.3 ppm?1 towards 0.1 ppm benzene, and ppb level sensitivity with 15.3 ppm?1 towards 50 ppb acetone, respectively.(2) The hollow ZnO/ZnFe2O4 microspheres with heterogeneous structure are synthesized by direct pyrolysis of metal-organic frameworks. Interestingly, the hollow ZnO/ZnFe2O4 microspheres based gas sensors show interestingly temperature-dependent n-p-n type conductivity transition in detecting low-concentration VOC gases. This interestingly n-p-n transition phenomenon is mainly ascribed to the trade-off of highly separated electron-hole pairs originated from the in-shell ZnO-ZnFe2O4 hetero-interfaces, resulting in the down-shift and up-shift of the Femi level. This conductivity transition significantly improves the selectivity of gas sensors

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/26886
Collection中国科学院过程工程研究所
研究所(批量导入)
Recommended Citation
GB/T 7714
李文辉. 烹饪油烟的高效分离、吸收-催化及快速检测技术探究[D]. 中国科学院研究生院,2018.
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