资源描述
suspended preheatingtechniqueA, suspended preheatingtechnique superiority Traditional dry process rotary kiln production of raw cement clinker, burn, decomposed and preheat the plume are completed in the process. Rotary kiln as burning into equipment, because it can provide section temperature distribution was homogeneous temperature field, and can ensure material at high temperatures have enough retention time, still can meet the requirements. But as heat and mass transfer equipment is not ideal, to need to heat larger preheating, decomposing process is very not adapt. This is mainly due to the accumulation in kiln stove bottom of materials, from material layer surface through air, air with material contact area small, heat transfer efficiency low be caused by. Meanwhile, the stove decomposing zone in feeding powder layered accumulation state, material layer to the internal decomposition out carbon dioxide small area, the spread of airflow resistance, slow, and material layer internal granules are carbon dioxide gas membrane packages, carbon dioxide, differential pressure decomposition temperatures the demand is high, it has increased the difficulty of carbonate decomposition and reduce the decomposition rate. Suspension preheater technical breakthroughs, fundamentally changed materials heat transfer condition, preheat the process of material accumulation state will the stove to warm-up and decomposing process, were moved to suspension preheater and decomposition furnace inner state of suspension. Due to suspension in heat flow of materials, and airflow greatly increased the contact area, so the heat transfer speed fast, heat transfer efficiency is very high. Meanwhile, raw fuel at powder and suspended configuration, mixing, fuel burning hot timely to raw material and make the rapid decomposition. Thus, due to rapid, heat transfer, mass transfer substantially improve the production efficiency and thermal efficiency. Second, the characteristics of suspension preheater kiln Suspension preheater kiln characteristic is in after a short length of rotary kiln installed suspension preheater, make originally in the states with accumulation plume material preheating and part of carbonate decomposing process, moved to suspension preheater through suspension state within a state of suspension, so the raw with heat flow powder, fully contact with the gas and solid phase interface big, heat transfer speed, high efficiency, improve the kiln production ability, reduce the heat consumption of clinker burn. At the same time it still has few movement part, accessory equipment, maintenance is simpler, small area is lesser, investment costs lower advantages. Three, suspension preheater the composition and function Suspension preheater mainly cyclone preheater and made tube preheater two kinds. Tube preheater has now made tends to eliminated. Pre by cyclone preheater decompose kiln as preheating unit equipment. Constitute a cyclone preheater heat transfer unit equipment is mainly a whirlwind tube and tube at various levels between whirlwind of connecting pipeline (also called heat pipe). The main function of suspension preheater is fully utilize rotary kiln and the drain of decomposing furnace hot airflow which heat enthalpy heat raw, make preheated and part, and then into carbonate decomposition of decomposing furnace or rotary kiln, continue the heating decomposition burn complete clinker task. So it must have contentious, solid two-phase can fully scattered uniform, rapid heat transfer, efficient separation and three functions. Only these three functions, and both of trying to make highlyeffective, can maximize thermal for whole kiln system, high quality, high efficiency, low consumption and stable production create conditions. Cyclone preheater functions to dispersing materials in hot airflow, uniform, gas-solid in heat and separation. Its performance quality mainly displays in whether has the high thermal efficiency, low, separation of resistance and good sealing performance to reduce internal and external air leakage, etc. Cyclone preheater is by a whirlwind tube and upper and lower two level a whirlwind cylinder composed the connections between pipeline. Part of the whirlwind canister ontology cylinder, the cone, a pipeline, export pipeline, imported material pipe inner cylinder and etc. Connecting pipe upside and superior a whirlwind tube inlet piping, lower and lower a whirlwind tube outlet piping connections; Proper position superior a whirlwind among the next feed tube and tube the connection; Whirlwind tube feeding at a higher level under proper positions of the pipe, air valve installed a locked not only keep the role is separated from the superior a whirlwind canister to expedite raw through the heat pipe, and can maximize prevent lower the heat whirlwind canister out under short-circuit feed tube flows into superior a whirlwind tube, cause has been separation of secondary float in the sky, reduce powder raw superiors separation efficiency; whirlwind tube Whirlwind tube in superior under the lower feed tube with heat pipe joint and also has a feeder, the purpose is to make the tube down superior a whirlwind into heat pipe homogenizing powder, because gravity rushed in and splash rise, make the feeder can rapidly dispersing, powder raw edgeunder at a lower level of heat flow whirlwind canister out, improve thermal among. Traced back, as the cyclone preheater whirlwind of the main part in general cone, is the whirlwind dust collector based on reference over the development. Both have in common is to keep low-pressure loss status has higher gas-solid separation efficiency. But differences lies in, cyclone dust collector dont have heat transfer function, and should have the highest possible gas-solid separation function; And for cyclone preheater whirlwind of main equipment cartridge speaking, because it is by multilevel heat transfer units, material is composed by a multi-stage preheating unit, so just keep uploaded heating gas-solid separation of the given the heat transfer efficiency and must complete a due role that task. So it in cyclone preheater system, depending on the place of different preheater level, have different gas-solid separation efficiency targets, and its itself structure also has difference. So the dusty airflow finally get separated. The gas and dust in different physical characteristics, main show is in a gaseous materials, quality is lesser, easy deformation; Another is larger, solid material, quality is out of shape not easily. So, when the dusty air role to by centrifugal force whirlwind tube wall enrichment, it was a gas centrifugal and thus dust in mechanics have conditions will air extrusion, and concentrated in the hollow, and airflow is attached with a layer of dust in. When the dusty airflow movement, dust, a force for air, the motion of local change airflow; Meanwhile airflow a reaction which to dust to dust, this is the resistance of the air. The resistance theoretical analysis and scientific experiments that affect both whirlwind cone fluid resistance and separation efficiency basically has two big factors, a whirlwind of geometric structure is cartridge, the second is a fluid itself physical properties. Because as used in cement industry suspension preheater whirlwind tube, its handling of airflow dusty defined roughly physical properties. Four, the influence of thermal efficiency and the dedusting efficiency factors 1, leak air of influence Whirlwind tube as cement suspension preheater decomposition process important equipment, its air leakage, whether in the air leakage or air leakage, is harmful. Preheat system directly affects its outside air leakage and increase efficiency, exhaust fan power consumption, and feed tube place in air leakage makes whirlwind canister separation efficiency sharply reduced the fly ash, system, causing an indirect influence ratio increases the preheater system thermal efficiency. In the actual production process, preheater system outside air leakage are easy to spot. To strengthen management, improve operation personnel sense of responsibility, outside air leakage can be controlled. But the next feed tube place within the air leakage, often with operators, experience judgment will not be discovered. Currently used flap valve unloader device, in order to prevent and smooth unloading, often allows certain by turning the volume in leak into the next makings tube, so adopt flap valve unloading may not fundamentally eliminate air leakage within. Research on a whirlwind tube leakage separation efficiency, looking for the influence of the effective measures to reduce the harm of fly ash, reduce the quantity and improve efficiency of the preheater kiln system has important significance. Next feed tube place from air leakage points whirlwind canister unloading mouth closer, air leakage caused a whirlwind of mono reduction separation efficiency is larger. In the actual production process, the flap valve unloading cannot completely prevent leakage within. Appropriate extension with a whirlwind flap valve installation position cartridge unloading mouth, can increase the distance between the whirlwind canister separation efficiency. 2, the influence of whirlwind tube import wind speed Different wind conditions, with imported whirlwind tube import wind speed increase, next makings pipe leakage caused a whirlwind tube in reduction of separation efficiency increase, if keep constant, the air leakage of air leakage caused by imported wind speed reduction and separation efficiency whirlwind canister less effect. 3 and solid gas ratio influence Solid/gas ratio under different in feed tube and air leakage caused a whirlwind canister reduction separation efficiency is different also with solid/gas ratio increases, down feed tube leakage caused a whirlwind tube in reduction of separation efficiency increases at the same time. But, for a given leakage rate, with solid/gas ratio increases, the difference in value and separation efficiency gradually narrowing. The greater the solid/gas ratio, feed tube place air leakage caused a whirlwind tube material unloading mouth place more serious phenomenon also shed. This may be solid/gas ratio in the next feed tube and air leakage caused a whirlwind canister the separation efficiency of the reduction of reason. 4, a whirlwind canister influence of the structure of 2 Whirlwind cylinder is generally rectangles 2 structure, a new type of low-pressure loss due to the structure type whirlwind tube changes and geometrical shape of 2 also change, some use five-sides, some use diamond, aims to guide into a whirlwind of mono under gas-solid flow deflection movement, reduce a whirlwind canister resistance. Whirlwind tube import way generally has two kinds, namely import airflow tillu tangent says straight with cylinder type; Airflow around the tangent says with spiral type cylinder. Due to import can make spiral into a whirlwind of cylinder, air passage gradually narrowed to help to reduce the distance of inner particles move, the distance to increase airflow exhaust, avoid short circuit, can improve the separation efficiency. But also has a deal with pressure loss of air, the advantages of small, reason often used. 5, tube insertion depth The increase of steel-flue insert depth, the resistance coefficient and separation efficiency is the increase of different processes. Insert depth, and imported high tube ratio of s/a = o. 482-0.612 range, low resistance coefficient little change, and separation efficiency increases slightly, so sure of separation efficiency should be emphasized the intermediate level resistance reduction whirlwind cylinder should be in s/a 0.612 or so, and had better not & lt; Separation efficiency 0.482 (too much), also dont reduce of& gt; 0.816 (resistance coefficient increases too big); But the separation efficiency emphasized at the next higher level shall be s/a whirlwind tube in 1.02 left and right sides, because when s/a 1.02 separation efficiency increase when. 6 and the influence of tube diameter With the expansion of inner cylinder diameters, the resistance coefficient and separation efficiency of different diameter reduced, including D 2/3, drag coefficient reducing slowly. For separation efficiency, it D O. 6, separating efficiency decreases rapidly. So guarantee of separation efficiency should be emphasized the intermediate level resistance reduction whirlwind in the cylinder tube diameter size, d/d can be in 2/3 or so, and had better not & gt; 2/3, otherwise the resistance coefficient reducing much bigger; the separation efficiency and reduce Also dont & lt; 0.6, or resistance coefficient increases too big; But the separation efficiency emphasized at the next higher level within the whirlwind tube diameter size, d/reduction should be & lt; d 0.6, because when d/D 0.6 separation efficiency reduce when more. Not quite, but the resistance coefficient increases to a certain extent. 7, a whirlwind tube high aspect ratio Along with the increase of whirlwind canister height, the resistance coefficient and separation efficiency of different reduce respectively, it especially with increase in when a whirlwind tube diameter ratio H/high D 2.282, drag coefficient and separation efficiency as a whirlwind canister height respectively increased decreases and increased slowly. So consider the height and preheater tower under the premise of an investment cost, best can guarantee a whirlwind tube diameter ratio around in high 2.282, because too low, and separation efficiency reduce resistance coefficient increases. But due to high separation efficiency and resistance coefficient increases and reduce respectively, and few whirlwind canister height and equipment costs have increased to a certain extent. Five, the normal production inspection and maintenance of mainly include the following aspects: (1) a normal production process of the electric dust removal valve condition; (2) system seal condition; (3) decomposition furnace, a whirlwind tube and connecting pipe shell without exception (such as: the night observing shell domestic village peel off and then red); (4) the whirlwind tube blow plugging device might be flexible motion (electromagnetic valve), blow plugging pneumatic meets the standards; (5) artificially block clearer tools are ready; (6) system temperature sensor, pressure measuring device is stable and reliable; (7) decomposition furnace burner without exception combustion; (8) system safety protective measures for completeness. Six, stop kiln maintenance preheater and decomposition furnace examination (1) check cyclone furnace tube and decomposition without off brick or the eyewinker, inner cylinder are in good condition; Horizontal line without off brick, inside, feeding material should be clear in time too; Rising pipe; without off brick Guide plate, and materials plate is in good condition. (2) check the electric dust removal valve bearing, when necessary, lubricates the clean and refueling; Check the electric dust removal valve surface is in good condition, if appear valve face severe worn or serious deformation, should promptly replaced. (3) to examine decomposition furnace burner is in good condition, such as the discovery of a badly worn or deformation should be replaced. (4) check mouth, preheater shrinkage and discharge smoke room without crust tongue phenomenon, such as a crust should be timely clearing. (5) system maintenance overhaul after each part of the system should be unblocked, and presence of foreign body, the electric dust removal valve activities is flexible, after the check should shut down all observations hole and into the hole of the door, completes the system sealing job. 悬浮预热技术一、悬浮预热技术的优越性传统干法回转窑生产水泥熟料，生料的预热、分解和烧成过程均在窑内完成。回转窑作为烧成设备，由于它能够提供断面温度分布比较均匀的温度场，并能保证物料在高温下有足够的停留时间，尚能满足要求。但作为传热、传质设备则不理想，对需要热量较大的预热、分解过程则甚不适应。这主要由于窑内物料堆积在窑的底部，气流从料层表面流过，气流与物料的接触面积小，传热效率低所致。同时，窑内分解带料粉处于层状堆积态，料层内部分解出的二氧化碳向气流扩散的面积小、阻力大、速度慢，并且料层内部颗粒被二氧化碳气膜包裹，二氧化碳分压大，分解温度要求高，这就增大了碳酸盐分解的困难，降低了分解速度。悬浮预热技术的突破，从根本上改变了物料预热过程的传热状态，将窑内物料堆积态的预热和分解过程，分别移到悬浮预热器和分解炉内在悬浮状态下进行。由于物料悬浮在热气流中，与气流的接触面积大幅度增加，因此传热速度极快，传热效率很高。同时，生料粉与燃料在悬浮态下，均匀混合，燃料燃烧热及时传给物料，使之迅速分解。因此，由于传热、传质迅速，大幅度提高了生产效率和热效率。二、悬浮预热窑的特点悬浮预热窑的特点是在长度较短的回转窑后装设了悬浮预热器，使原来在窑内以堆积态进行的物料预热及部分碳酸盐分解过程，移到悬浮预热器内以悬浮状态进行，因此呈悬浮状态的生料粉能与热气流充分接触，气、固相接触面大，传热速度快、效率高，有利于提高窑的生产能力，降低熟料烧成热耗。同时它尚具有运动部件少，附属设备不多，维修比较简单，占地面积较小，投资费用较低等优点。三、悬浮预热器的构成及功能悬浮预热器主要有旋风预热器及立筒预热器两种。现在立筒预热器已趋于淘汰。预分解窑采用旋风预热器作为预热单元装备。构成旋风预热器的热交换单元设备主要是旋风筒及各级旋风筒之间的联接管道（亦称换热管道）。悬浮预热器的主要功能在于充分利用回转窑及分解炉内排出的炽热气流中所具有的热焓加热生料，使之进行预热及部分碳酸盐分解，然后进入分解炉或回转窑内继续加热分解，完成熟料烧成任务。因此它必须具备使气、固两相能充分分散均布、迅速换热、高效分离等三个功能。只有兼备这三个功能，并且尽力使之高效化，方可最大限度地提高换热效率，为全窑系统优质、高效、低耗和稳定生产创造条件。旋风预热器的功能在于物料在炽热气流中的分散、均布、气固换热和分离。其性能优劣主要表现在是否具有较高的换热效率、分离效率，较低的阻力和良好的密闭性能以减少内、外漏风等。旋风预热器系由旋风筒及上、下两级旋风筒间的连接管道所组成。旋风筒本体的组成部分有圆柱体、圆锥体、进口管道、出口管道、内筒及下料管等。连接管道上部与上级旋风筒进口管道、下部与下级旋风筒出口管道相连接；中间适当部位有上级旋风筒的下料管与之连接；在上级旋风筒下料管内的适当部位装设有锁风阀，作用在于既保持上级旋风筒分离出的生料能够畅通的通过进入换热管道，又能最大限度地防止下级旋风筒出来的热气流经下料管短路窜入上级旋风筒，造成已被分离的生料粉二次飞扬，降低上级旋风筒的分离效率；在上级旋风筒下料管最下部与换热管道的连接部位还设有撒料装置，目的在于使上级旋风筒下来的生料粉进入换热管道时，由于重力作用冲在撒料器上飞溅起来，使生料粉能够迅速分散、均布在下级旋风筒出来的热气流之中，提高换热效率。追根溯源，作为旋风预热器的主要组成部分的旋风筒，是在普通的旋风收尘器的基础上借鉴发展过来的。两者的共同点在于保持低压损状态下能具有较高的气固分离效率。而不同点则在于，旋风收尘器不具备换热功能，而应具备尽可能高的气固分离功能；而对旋风预热器中的主要设备旋风筒来讲，由于它是由多级换热单元所组成，物料系由多级预热单元逐级加热，因此只要保持其给定的气固分离效率和一定的换热作用即完成了应有的任务。所以它在旋风预热器系统中，视所在的不同预热器级别，具有不同的气固分离效率目标，而其本身结构亦有差异。从而使得含尘气流最后得到分离。气流和粉尘的不同物理特性，主要表现在一个是气态物质，质量较小，容易变形；另一个是固态物质，质量较大，不易变形。所以，当含尘气流受离心力作用，向旋风筒内壁浓缩时，它所受到的离心力较气体大，因此粉尘在力学上有条件将气流挤出，而浓缩于筒壁，而气流则贴附于粉尘层上。当含尘气流运动时，粉尘给气流一个作用力，可局部改变气流的运动状态；同时气流也给粉尘一个反作用力，这就是气流对粉尘的阻力。这个阻理论分析及科学实验均说明，影响旋风筒流体阻力及分离效率主要有两大因素，一是旋风筒的几何结构，二是流体本身的物理性能。由于作为用于水泥工业悬浮预热装置的旋风筒，其所处理的含尘气流的物理性能大致确定。四、影响热效率及收尘效率的因素1、漏风的影响旋风筒作为水泥悬浮预热分解工艺过程的重要设备,其漏风,无论是内漏风还是外漏风,都是有害无益的。预热系统的外漏风直接影响其热效率,并增大排风机功率消耗,而下料管处内漏风则使旋风筒的分离效率急剧降低,系统飞灰量增大,从而间接影响预热器系统的热效率。在实际生产过程中,预热器系统的外漏风容易被发现。加强管理,提高操作人员的责任心,外漏风可以得到控制。但是下料管处的内漏风通常靠操作人员的经验判断,不易被发现。目前普遍使用翻板阀卸料装置,为了防堵和顺畅卸料,经常允许一定的气量由翻板处漏入下料管,所以采用翻板阀卸料不可能从根本上完全杜绝内漏风。研究漏风对旋风筒分离效率的影响,寻找减小其危害的有效措施,对降低飞灰量及提高预热器窑系统的热效率具有重要意义。下料管处漏风点距旋风筒卸料口越近,漏风导致旋风筒的分离效率降低幅度越大。在实际生产过程中,翻板阀卸料无法完全杜绝内漏风。适当延长翻板阀安装位置与旋风筒卸料口之间距离,可以提高旋风筒的分离效率。 2、旋风筒进口风速的影响不同进口风速条件下,随着旋风筒进口风速增大,下料管处漏风导致旋风筒分离效率降低幅度增大,若保持漏风量恒定不变,则进口风速对因漏风导致旋风筒分离效率降低幅度的影响较小。 3、固气比的影响 固气比不同,下料管处漏风导致旋风筒分离效率降低幅度也不同随着固气比增大,下料管处漏风导致旋风筒分离效率降低幅度也增大。但是,对于给定的漏风率,随着固气比增大,分离效率的差值逐渐缩小。固气比愈大,下料管处漏风导致旋风筒卸料口处棚料现象也愈严重。这可能就是固气比越大,下料管处漏风导致旋风筒分离效率降低幅度越大的原因。 4、旋风筒进风口结构的影响旋风筒进风口结构一般为矩型，新型低压损旋风筒由于结构型式的变化和进风口的几何形状亦有所变化，有的采用五边形，有的采用菱形，目的在于引导进入旋风筒的气固流向下偏斜运动，减少旋风筒阻力。旋风筒进口方式一般有两种，即进口气流外缘与圆柱体相切称直式；气流内缘与圆柱体相切称蜗壳式。由于蜗壳式进口能使进入旋风筒气流通道逐渐变窄，有利于减小颗粒向筒壁移动的距离，增加气流通向排气管的距离，避免短路，可提高分离效率。同时还具有处理风量大，压损小的优点，故常被采用。5、内筒插入深度内筒插入深度的增加，其阻力系数和分离效率有着不同程的增加。在内筒插入深度与进口高度的比值sa=O4820612范围内，阻力系数较低且变化不大，分离效率略有增加，所以保证一定的分离效率要着重强调降阻的中间级旋风筒sa应在0612左右，且最好不要<0482(分离效率降低太多)，也不要>0816(阻力系数增加太大)；而着重强调分离效率的最上一级旋风筒sa应在102左右，因为当sa<102时分离效率降低较多，当sa>102时分离效率增加。6、内筒直径的影响随着内筒直径的扩大，其阻力系数和分离效率有着不同程度的减小，在内筒直径dD<23时，阻力系数快速下降，当dD>23时，阻力系数减小缓慢。对于分离效率来说，内筒直径dD<O6时分离效率较高且变化不大，当dD>O6时，分离效率减小较快。所以保证一定的分离效率要着重强调降阻的中间级旋风筒内筒直径大小，dD可以在23左右，且最好不要>23，否则阻力系数降低不多而分离效率降低较大；也不要<06，否则阻力系数增加太大；而着重强调分离效率的最上一级旋风筒内简直径大小，dD应<06，因为当dD>06时分离效率降低较多。不大，但阻力系数有一定程度的增加。7、旋风筒高径比随着旋风筒高度的增加，其阻力系数和分离效率分别有着不同程度的减小和增加，这一点尤以当旋风筒高径比HD<2282时表现更加明显，但当HD>2282时，阻力系数和分离效率分别随着旋风筒高度的增加而减小和增加缓慢。所以在考虑窑尾塔架高度和一次投资成本的前提下，最好能够保证旋风筒高径比在2282左右，因为过低时分离效率降低，且阻力系数增加。但过高时由于分离效率和阻力系数分别增加和降低不多，而旋风筒高度及设备成本却有一定程度的增加。五、正常生产时的检查与维护主要包括以下几方面：（1）正常生产过程中排灰阀状况；（2）系统的密封状况；（3）分解炉、旋风筒及连接管道壳体有无异常（如：夜间观察壳体国内村脱落而起红）；（4）各旋风筒的吹堵装置是否动作灵活（电磁阀），吹堵气压是
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