滚筒干燥机 开题报告 吕春辉

编号无锡太湖学院毕业设计（论文）相关资料题目： 滚筒干燥器设计 信机 系 机械工程及自动化专业学 号： 0923011学生姓名： 吕春辉 指导教师： 戴宁 （职称：副教授 ） （职称： ）2013年5月25日目 录一、毕业设计（论文）开题报告二、毕业设计（论文）外文资料翻译及原文三、学生“毕业论文（论文）计划、进度、检查及落实表”四、实习鉴定表无锡太湖学院毕业设计（论文）开题报告题目： 滚筒干燥器设计 信机 系 机械工程及自动化 专业学 号： 0923011 学生姓名： 吕春辉 指导教师： 戴宁 （职称：副教授 ） （职称： ）2012年11月25日 课题来源工程实践类的自拟课题科学依据（包括课题的科学意义；国内外研究概况、水平和发展趋势；应用前景等）（1）课题科学意义干燥技术的应用，在我国具有十分悠久的历史，闻名于世的造纸技术就有干燥技术的应用。干燥设备广泛应用于化工、食品、粮油、饲料等工业。中国的现代干燥技术是从20 世纪50年代逐渐发展起来的，迄今对于常用的干燥设备如气流干燥、喷雾干燥、流化床干燥、旋转闪蒸干燥、红外干燥、微波干燥、冷冻干燥等设备，我国均能生产供应市场。对于一些较新型的干燥技术如冲击干燥、对撞流干燥、过热干燥、脉动燃烧干燥、热泵干燥等也都已开发研究，有的已工业化应用。我国的现代干燥技术取得的成绩是我国相关科研人员和企业界共同努力的结果，虽然取得了不少可喜的成果，但是企业间的竞争尚不规范阻碍了干燥技术的健康发展，很多成果尚未能转化为生产力使企业的产品得不到更新。（2）国内外研究概况及发展前景干燥也是一个能耗较大的单元操作，直接决定着产品的质量，特别是高性能材料的生产，对干燥操作有着更高的要求。针对这些问题，近些年来，干燥技术领域出现了一些创新成果。为了节能以及生产附加值高的产品、解决干燥过程中出现的问题需要结合现存的各种有效的干燥技术，或者研究开发特殊的干燥技术和新型的干燥设备同时也需要强化干燥过程中的智能化控制。在油脂制取的原料干燥上目前我国此类干燥设备大部分是采用对流干燥技术,主要使用滚筒烘干机、流化床烘干机和塔式干燥机。 简而言之，目前干燥技术发展的总趋势为:a.干燥设备研制上向专业化、大型化、系列化和自动化发展。b.强化干燥过程。c.采用新的干燥方法和组合干燥方法。d.降低干燥过程中能量的消耗。e.闭路循环干燥流程的开发和应用。f.消除干燥过程造成的公害问题。 研究内容 熟悉滚筒干燥器的主要原理和结构。 熟悉干燥过程的基本计算； 熟练进行滚筒干燥器的结构设计； 掌握的使用方法； 能够熟练使用进行三维的画图设计。 拟采取的研究方法、技术路线、实验方案及可行性分析（1）实验方案对滚筒干燥机进行设计，结构合理、布局正确，能够正常运行。（2）研究方法 用进行二维画图，对滚筒干燥器的结构有全面的了解。 对滚筒干燥机进行计算与结构设计，使其满足工作要求。研究计划及预期成果研究计划：2012年10月12日-2012年12月31日：按照任务书要求查阅论文相关参考资料，完成毕业设计开题报告书。2013年1月1日-2013年1月27日：学习并翻译一篇与毕业设计相关的英文材料。2013年1月28日-2013年3月3日：毕业实习。2013年3月4日-2013年3月17日：滚筒干燥器的主要参数计算与确定。2013年3月18日-2013年4月14日：滚筒干燥器总体结构设计。2013年4月15日-2013年4月28日：零件图及三维画图设计。2013年4月29日-2013年5月21日：毕业论文撰写和修改工作。预期成果：滚筒干燥器可以正常运行，完成人们所需的成品。特色或创新之处 设备传热效率高、传热均匀。 设备结构简单、易操作。已具备的条件和尚需解决的问题 设计方案思路已经明确，已经具备机械设计能力和干燥方面的知识。 进行结构设计的能力尚需加强。指导教师意见 指导教师签名：年 月 日教研室（学科组、研究所）意见 教研室主任签名： 年 月 日系意见 主管领导签名： 年 月 日英文原文Drying TechnologyThere are three main types of gas-suspension dryers: Spray dryers, to convert a liquid solution or suspension to a dry, free-flowing powder Fluid-bed dryers, used to dry wet filter cake, or for pastes and sludges with dry product recirculation Flash dryers, for a relatively dry, crumbly, non-sticky feed The type of dryer chosen for any given application depends on both the feed properties and product requirements. Important feed properties are the moisture content, solids, viscosity, and density, as well as any volatile, flammable, or toxic components. Dried product specifications may include average particle size and particle size distribution, density, moisture content, and residual volatiles or solvents. Powder characteristics can be controlled and powder properties maintained constant through continuous operation.Spray DryingSpray drying is a three-step drying process involving both particle formation and drying. (1) The process begins with the atomization of a liquid feed into a spray of fine droplets. (2) Then a heated gas stream suspends the droplets, evaporating the liquid and leaving the solids in essentially their original size and shape. (3) Finally, the dried powder is separated from the gas stream and collected. Spent drying gas is either treated and exhausted to the atmosphere or recirculated to the system. These three steps are accomplished by three components: the atomizer, the disperser, and the drying chamber.The selection and operation of the atomizer is of extreme importance in achieving an optimum operation and production of top-quality powders. There are four main types of atomization: Centrifugal atomization, the most common, uses a rotating wheel or disc to break the liquid stream into droplets. The rotational speed determines the mean particle size, while the particle size distribution about the mean remains fairly constant in a system. Centrifugal atomizers are available in a large variety of sizes, from laboratory scale to very large commercial units. Hydraulic pressure-nozzle atomization forces pressurized fluid through an orifice. Multiple nozzles are used to increase capacity. The particle size depends on the pressure drop across the orifice, so that the orifice size determines the capacity of the system. This type of atomization is simpler than centrifugal, but cannot be controlled as well. It is not suitable for abrasive materials, or materials that tend to plug the orifices. Two-fluid pneumatic atomization uses nozzles, as well, but introduces a second fluid, usually compressed air, into the liquid stream to atomize it. This type of atomization has the advantage of relatively low pressures and velocities and a shorter required drying path. It is most often used in small-scale equipment, laboratory or pilot size. Sonic atomization, not yet widely used, passes a liquid over a surface vibrated at ultrasonic frequencies. It can produce very fine droplets at low flow rates. Current limitations are capacity and the range of different product that can be atomized. After atomization, a disperser brings the heated gas into contact with the droplets. The disperser must accomplish three things: mix the gas with the droplets, begin the drying process, and determine the flow paths through the drying chamber. The drying gas may be heated directly by combustion of natural gas, propane, or fuel oil, or indirectly using shell-and-tube or finned heat exchangers. Electric heaters may be used in small dryers. Industrial radial fans move the heated gas through the system.The drying chamber must be sized to allow adequate contact time for evaporation of all of the liquid to produce a dry powder product. Factors that impact the drying time include the temperature difference between the droplets and the drying gas, and their flow rates. The exact shape of the chamber depends on the drying characteristics and product specifications, but most are cylindrical with a cone-shaped lower section to facilitate collection of the product.Finally, proper configuration of the atomizer, disperser, and drying chamber is essential for complete drying and to avoid the deposit of wet material on the interior surfaces of the dryer. Designs may use co-current, counter-current, or mixed flow patterns.The powder is separated from the drying gas at the bottom of the chamber. Most often, the gas exits through an outlet duct in the center of the cone. Heavier or coarser particles will be separated at this point, dropping into the cone to be collected through an air lock. Then either cyclones or fabric filters (or both) remove the remaining powder from the exit gas. In systems producing a very fine powder, most of the collection takes place at this point.Fluid-Bed DryingFluid-bed drying is a process in which a gas is forced upward through a bed of moist particles to achieve a fluidized state. The particles are suspended in the gas stream and dry as they flow along with the gas. Fluid beds can be either cylindrical or rectangular. There are two basic types of fluid-bed designs: Plug flow fluid beds are used for feeds that are directly fluidizable. Baffles in the bed limit mixing in the horizontal direction to maintain plug flow. This type of bed is ideal for removal of bound volatiles or for heating and cooling. The volatile content and temperature vary uniformly as the solids pass through the bed. Baffle design depends on the shape and size of the bed, with spiral or radial baffles used in circular beds and straight baffles in rectangular. Back-mixed fluid beds are used for feeds that cannot be fluidized in their original state, but become fluidizable after a short time in the dryer. The feed is distributed over the bed surface, designed to allow total solids mixing. Product temperature and moisture are uniform across the fluidized layer. Heating surfaces may be immersed in the fluidized layer to improve thermal efficiency and performance. A combination system uses a back-mixed fluid bed to reduce the moisture level of the wet feed, followed by a plug-flow section to achieve final specifications. This type of arrangement is quite common.The advantages of fluidized-bed drying are: relatively long residence times allow high heat-transfer coefficients between the particles and the gas; the ability to closely control product temperature makes fluidized beds ideal for processing temperature-sensitive solids; and they have the highest thermal efficiency of any gas-suspension drying system.Disadvantages are: they can process only a limited range of materials; product particles are relatively large; and there may be difficulty processing needle- or platelet-shaped particles.Flash DryingFlash drying forces drying gas through a heater and upward through a duct or flash tube. The high-velocity gas stream instantly suspends the feed, which enters just after the heater, and carries it to the collection equipment, usually cyclones or bag collectors.Flash dryers are the simplest gas-suspension dryers, and require the least space. Residence time within the dryer is very short, usually less than 3 seconds. Particles must be quite small, and the best feed is reasonably dry, crumbly, and not sticky. There are several ways to obtain the required feed qualities: A cage mill may be used to break up the feed into the required small particles. If the feed is too wet or pasty, dry solids may be backmixed to create the proper consistency. An agitated design, using a high-speed disintegrating rotor, will keep all particles moving. This design is shorter and larger in diameter than a flash tube, creating a very compact system. Hybrid DryersThere are a number of hydrid systems used in applications where a single system cannot handle the requirements of both the feed and product. The most common are: Fluidized spray dryers (FSD) combine spray with fluid bed drying to produce agglomerated products. The top of the system is a spray dryer, atomizing the liquid and contacting it with heated gas. Additional heated gas is introduced at the bottom to create a fluidized bed portion of the drying chamber. This type of dryer will produce a dustless, free-flowing agglomerated product. It is ideal for products that must dissolve easily, e.g. food colors, dyestuffs, pigments, and some agricultural chemicals. A flash dryer may be used to remove surface moisture, followed by a fluid bed for removal of bound moisture. Niro DryersThe MOBILE MINOR is a laboratory-scale spray dryer known for its flexibility and different levels of control systems. It is used to dry small quantities of solutions, suspensions, and emulsions into representative powder samples. Test results provide important information for selecting the design and technical specification of a given drying project.The PRODUCTION MINOR is a larger spray dryer that can be used for pilot testing or small-scale production. It has a choice of atomizers, heating systems, and powder discharge.The Fluidized Spray Dryer (FSD) was invented and patented by Niro in the early 1980s. It combines fluidization and spray-drying technologies to dry a wide variety of products, including many that cannot be dried using conventional equipment. Advantages include easy control of the size and structure of the particles, making it ideal for agglomerated products, and low powder temperatures for thermally sensitive materials. It is also very energy efficient.中文译文干燥技术主要有三种气体悬浮烘干: 喷雾干燥器,把液体溶液或悬浮于干燥,自由流动的粉末 流化床干燥机,用干,湿滤饼,或浆和污泥干产品再循环 闪蒸干燥机,在相当干燥,松软,非饲料粘粘 该型干燥器选择任何特定应用取决于双方的饲料性能和产品的要求. 重要饲料性能是水分含量,固形物,粘度,密度,以及任何挥发性,易燃或有毒成分. 木片产品规格可能包括平均粒度分布,密度,含水率,残留挥发或溶剂. 粉末特性可控制粉末特性保持不变,通过连续运行. 喷雾干燥. 喷雾干燥是一个三步走的干燥过程中,涉及两种粒子形成和干燥. ( 1 )进程始于雾化的液体饲料成喷雾雾滴. ( 2 ) ,然后加热气流暂时飞沫 96.3%的液体和离开固体基本上是原来的大小和形状. ( 3 )最后,干粉分离气流和收集. 用干燥气体要么是治疗和精疲力竭的气氛或循环使用该系统. 这三个步骤是由三部分组成:雾化,分散,而干燥室.选择和操作的喷雾器,是极端重要性,实现最佳的操作和生产顶级质量 粉末. 主要有4种雾化: 离心雾化,最常见的,用一个旋转轮或盘打破液体流成液滴. 转速确定的平均粒径, 而粒度分布大约平均维持在相当稳定的系统. 离心式雾化器可有多种尺寸,从实验室规模比较大的商业单位. 液压喷嘴雾化势力加压流体通过一个小孔. 多喷头用来增加容量. 颗粒大小取决于压降过孔板, 使孔大小决定了系统的容量. 这种雾化简单得多离心,但无法控制等. 它是不适合研磨材料,或材料,往往堵塞孔口. 双流体气动雾化喷嘴的用途,以及如何引进,但第二液,通常压缩空气 成液体流雾化. 这种雾化的优点在于较低的压力和速度,缩短干燥所需的路径. 这是最常用的小型设备,实验室或中试规模. 声波雾化,尚未广泛使用,在经过了超过液体表面振捣,在超声波的频率. 它可以产生非常细微的动作,在低流率. 电流限制能力,以及各种不同的产品,可雾化.雾化后,使分散的炽热气体接触到液滴. 分散必须完成三件事:混合气体与雾滴,从干燥过程中, 并确定流路径通过干燥室. 干燥气体,可直接加热燃烧天然气,丙烷或燃油 或间接使用壳管式或翅片式换热器. 电加热器,可用于小型烘干机. 工业径向球迷提出了激烈的天然气通过该系统. 烘干室必须大小以便有充裕的时间接触蒸发所有的液体产生 一个干粉产品. 因素的影响,干燥时间,包括温差的雾滴和干燥气体. 而其流率. 确切庭取决于干燥特性及产品规格, 但大多数是圆柱与锥形下段,以方便收集的产品. 最后,妥善配置的喷雾器,播种机, 和干燥室必须彻底干燥,以避免存款湿材料的内表面 在吹干. 设计可利用顺流,逆流或混合流模式. 粉末分离的干燥气室底部. 在多数情况下,出口气体通过一个插座导管中心的锥. 较重或粗