小型冷库设计【含CAD图纸】
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西安文理学院本科毕业设计(论文)指导教师评分表学生姓名安剑学 号08102080219专 业机械设计制造及其自动化班 级08级机械2班毕业设计(论文)题目小型冷库设计设计(论文)起止时间2012年1月10日至2012年5 月18日指导教师评语:建议成绩:指导教师签名: 年 月 日西安文理学院本科毕业设计(论文)评阅教师评分表学生姓名安剑学 号08102080219专 业机械设计制造及其自动化班 级08级机械2班毕业设计(论文)题目小型冷库设计设计(论文)起止时间 2012年1月10日至2012年5 月18日评阅教师评语:建议成绩:评阅教师签名: 年 月 日附录外文文献The energy-conservation of freezer, with automaticallying control1 A present freezer of automatic control current situations Though the cold storage self-control having been popularized all round, but great majority cold storages putting particular emphasis on is only a safeguard face to face , the energy conservation having increased Wenku picking up the self-adjustment and cold storage measuring and controlling, to entire system relates that under the control of seldom or. Even if another aspect, already getting the all-round universal safeguard, before actual condition in working cant admit of no sanguine, pins up the cold storage self-control facilities having become ear of the deaf person even having become furnishing and decorating decorating front appearance only. The Shanghai cold storage association has done investigation in recent years to Shanghai area ammonia refrigerating system cold storage safeguard and autocontrol condition , concrete conditions has seen that are what form l shows. A spot of should inquire into a data as the leopard has reflected current cold storage self-control general situationForm what 1 shows a self-control interposes and runs status though the very good cold storage only having 5 tidal current and direction accounting for 9% of the number counting, but it is these cold storages to have represented a nowadays. With the development of electron technology, the self-control component is more and more advanced , changeable procedure controller (PLC) and the PC function are more and more strong , self-control procedure is more and more perfect, system optimization and the energy conservation consciousness are also more and more strong. The cold storage energy conservation and the autocontrol relation are more and more rapid and intense , need the cold storage energy conservation to be ready for and composing much better, do well in and be engaged in better the autocontrol vitally needing right away. Above-mentioned example adopted by five cold storages representing tidal current in the nowadays and advanced level has all got the pretty important effect to realizing cold storage energy conservation.2 How be ready for cold storage energy conservation autocontrolFundamental above-mentioned content starting point is the cold storage taking ammonia as all together style refrigeration working medium refrigerating system , is that refrigeration working medium decentralization, allows all together style , all together style refrigerating system cold storage to have got very big development , whose self-control degree overtops also sometimes the all together style refrigerating system cold storage taking ammonia as refrigeration working medium on behalf of a hydrocarbon with the thick gravy nowadays. Many working mediums are unlike cold storage of system of all kinds extensive use, content having enriched cold storage autocontrol tremendously, application in energy conservation at the same time also has provided the vast scope for ones ability to autocontrol in the cold storage.2.1 Cold storage energy conservation autocontrol Cold storage energy conservation autocontrol is energy conservation under the control of procedure establishment and self-control component selecting and using from the content coming to study the autocontrol developing cold storage energy conservations relates that mainly whom. The firm, special field designing institute or capable unit as self-control component may assume cold storage energy conservation autocontrol research and develop equally. The firm and the designing institute make a contribution to some extent without exception already by now within that field. Cold storage energy conservation autocontrol can be developed exploitation commonly by firm and designing institute best (not bad firm give first place to, the designing institute coordinates) , perfects in the process of putting into effect using an unit the new product getting into form and grinding unceasingly to get rich.2.2 Energy conservation autocontrol specific items design prepares a cold storage putting composition into practice.That a specific items energy conservation autocontrols puts process into practice sometimes is that the purpose checking K amendment , reaching energy conservation until according with design demand by designing , assembling debugging , pilot run , effect is extremely. While the project requires that content is changed into a ratio to some extent, may revise K at any time satisfying a request.The cold storage energy conservation sometimes requires that the advanced refrigeration switches over to prepare , right system mates , effective the words emergency measure and strict operation manage to manage to be put into effect, be requiring that the refrigeration technician goes ahead in the basis optimizing refrigeration process design right now, know well that energy conservation needs , be tied in wedlock this project characteristic , the flow chart designing out entire cold storage energy conservation autocontrol. Ability accomplishes whose electricity self-control design according to the self-control flow chart , the electricity self-control technician , being able to wield whose professional knowledge at the same time, makes self-control technological process be simplification and an optimization more. Cold storage energy conservation is a cold storage autocontrol important component , all cold storage autocontrol is composed of refrigeration and electricity two parts content without exception , K makes cold storage energy conservation be carried out to the letter only when ability makes cold storage autocontrol come into effect in the field of two under technicians making joint efforts.3 Cold storage energy conservation autocontrol pilot run is also one very important ring , echoes the usage unit and the special field firm in the pilot run keeping close connection , uses an unit to discuss working effect , deliberates amendment measure with special field firm and.Energy conservation is one of cold storage autocontrol purpose. 3.1 Adjusts storehouse temperature adjustment in the past about that the storehouse temperature and the evaporation temperature adjust the parametric storehouse of 3.1.1 Storehouse temperature controlMultiple spots temperature temperature giving first place to dyadic adjustment of place, correct evaporate the temperature not sometimes doing adjustment , very difficult to reach good energy conservation effect. The ideal storehouse temperature control mode is that wind and their air-out temperature is entering parameter with the storehouse mean temperature , the air cooler moving forward , works out appropriate under the control of procedure , measures by the fact that PLC is in progress. So-called Wenku adjusts the request being able to reach energy conservation , also can satisfy the need that some storehouse high-accuracy temperature adjusts, self own but the accuracy reaching 0.250 C requires that energy conservation makes an appointment with 10% at present.3.1.2 Regard to relatively evaporate temperature higher cold right away be in no energy conservation operation statePs stop being unlike the diversity evaporates because K couplet operation can only work under evaporating the temperature with a with a systematic refrigeration compression engine evaporating the cold room of temperature temperature cold if K couplet work, with regard to relatively evaporate temperature higher cold right away be in no energy conservation operation state, should cold hot load increasingly be promoted to a higher post increasingly no energy conservation. Ought to try ones best to avoid this condition appearing. One machine reviews the cold storage method of work pair in freon refrigerating system , add the back pressure valve on time of high temperature warehouse air tube , add single check valve on time of low temperature warehouse air tube, be representative block of wood energy conservation method of work, do not respond to encourage but suitable abolish.3.1.3 Unexpected turn of events evaporates temperature adjustmentSome one work state lower if evaporate temperature can use storehouse hot load and refrigerating system refrigerating output be parameter be in progress adjustment, then now that can reach energy conservation purpose can make energy adjustment be more rational. The sort Er Yan , refrigerating system evaporation implement and refrigeration compression engine equipment can satisfy maximal load need basically all. Load falls off but the refrigerating output can not make corresponding adjustment in time if the cold room is hot, the refrigerating output and hot load being that the refrigerating system evaporation temperature will may act in responses reduces , uses a compression engine reach a new balance burning. The lessening evaporating the temperature has increased but the refrigerating output evaporating an implement conversely but , has faced the hot load that self own cuts down taking form surely frequently opening the consequence staying. Evaporate temperature 10 C per change, electric energy about 3 5% acting in responses adding or subtracting. Be energy conservation on making system burn in another ideal balance of if raising the evaporation temperature in time,have avoided freely not having achieved not only, having decreased by the refrigeration compression engines frequently starts , is the energy conservation measure achieving two things at one stroke. Not changeable fundamental refrigerant rate of flow rate of flow evaporating an implement adjusts. 3.1.4 Changeable rateChangeable rate of flow adjustment ammonia in the past refrigerating system; Freon system evaporates the implement refrigerant rate of flow , great majority achieve simple proportion measures. The air cooler air mass flow great majority do not measure or speed and the electric fan platform number measure only when two. This two kinds parametric rate of flow adjustment all are cold the adjustment assigning the equipment refrigerating output and storehouse temperature direct relevance , one of the content being also that the cold storage energy conservation self-control responds to in taking seriously with the storehouse.3.1.5 Fetch the warehouse taken height Sets up right under the control of accuracy and adds the storehouse temperature setting up the commodity and different storage period controlling the different storehouse , different stock out of gauge having no equal to and their under the control of accuracy request. Set off from the energy conservation angle, the storehouse temperature ought to take height not choosing low , the mild high-accuracy controlling accuracy ought to fetch the warehouse taken height , insisted to run after face to face unnecessarily low low controls as long as not affecting the commodity quality.To the cold room of many storehouse temperature under the control of, except original storehouse temperature setting value, suitable add set up Kuwen transfinite controlling value. This pair of factors storehouse temperature adjusts deflect but premature bringing into service being able to achieve when refrigerating system needs bringing into service , incapable because of pins up the storehouse temperature; Can not make cold according to reality that time at intervals, refrigerating system stops working untimely Ding , fully utilizes now having energy K avoid equipment or systematic frequently open Ding.3.1.6 Set up avoiding meeting high o perationInterpose avoid meeting high o operation under the control of electric power short-supplied be the universal phenomenon that current all parts of the country there exists in everywhere, huge bad especially heavy electric power of power consumption o grain is short-supplied , the electric charge o grain price differences puts into effect in a lot of city and price differences play big as early as successive steps for this purpose. Under the premise not affecting commodity mass, the cold storage is set up avoiding meeting high o peration , beneficial to the electrified wire netting cuts o repair a valley , help overall situation energy conservation on macroscopic view; Microcosmic Er Yan operation also beneficial toreducing a cold storage cost.3.2 Cold room relative humidities adjust cold room relative humidity adjustmentCold room relative humidities adjust cold room relative humidity adjustment and the temperatureadjusts the method similarity repeating description unnecessarily. But in general cold room relative humidity is in 85 the relative humidity that the also a little bit cold room demands is lower than or the relative humidity higher than the be 98%, but some crops of relative humidity kind of quality warehouse being range , for instance some gases turn to obj1 = 位 exchange the warehouse request demands 45% to be 40 between 95%. During the period of high relative humidity adjustment and low relative humidity adjustment, Youyin attaches importance to energy conservation measure.3.2.1 High relative humidities adjust the adjustmentHigh relative humidities adjust the adjustment demanding the cold room to high relative humidity , are going try ones best to reduce the logarithm averages difference in temperature (2 advisable K) between the refrigerant temperature and the storehouse temperature, return refrigerating system back when being necessary but adopt to be loaded with the cold agent first; May adopt air defrosting K besides with defrosting water restoring to the storehouse. That this two measure is given by autocontrol being put into effect, is effective energy conservation method , the domestic trade headquarter has not been 20,000 tons of Long Kou City gas that the research institute designs obj1 exchange a warehouse being a very good example of one 17 .3.2.2 Low relative humidities adjust the adjustmentLow relative humidities adjust the adjustment demanding the cold room to low relative humidity , controlling also should be ready for two aspect mainly. One is on the basis selecting and using dehumidification method and dehumidification machine stopping bringing quantity of heat into cold room to the full, hot few cold p rooms load controlling good dehumidification while procedure, reaching the relative humidity request. Its two is to avoid air current organizing the wet load controlling fever of taking now and then entering unnecessary outside; Once had the wet low one low temperature crops kind of quality warehouse, wet load roughly accounts for about35% of plain meter load from invading the heat within being put in storage outside.3.3 Measures about providing liquid wayDirect swelling is for liquids expanding directly to be for liquids being that great majority thick gravies pin up the confession liquid method that ammonia system adopts on behalf of hydrocarbon (include freon) system and . This provides liquid method with adopt the heating power expansion valve to provide liquid in the past basically , self problem, has no way to realize the energy conservation purpose since choosing the type , adjustment and product. Electron expansion valve appearing measures combining with selecting parametric Kuwen of temperature much , can realize energy conservation operation fairly good, sort but energy conservation 10%. But the thick gravy generation hydrocarbon refrigerating system heating power expansion valve product already be commensurate to maturity and still have the special-purpose PLC Kuwen controller, for a variety of reasons, adopt extension , wait for to increase energy not yet commonly in cold storage refrigerating system. Working hot shot degree of ammonia refrigerating system evaporation implement is not big , degree of difficulty is under the control of relatively bigger , there is no at present still mature ammonia using electron to expand ? ? valve product. The system 中文翻译冷库节能与自动控制1 当前冷库自控现状冷库自控虽然得到了全面普及,然而大多数冷库的侧重面只是安全保护,或者还增加了温库捡测和控制,对于全系统的自动调节和冷库的节能控制还很少涉及。另一方面,即便已得到全面普及的安全保护,在实际运行中的情况也不容乐观,个别冷库的自控设施甚至成了“聋子的耳朵”只成了装饰门面的摆设。近年来上海冷藏库协会对上海地区氨制冷系统冷库的安全保护和自动控制情况作了调查,具体情况见表l所示。该调查数据作为豹之一斑反映了当前冷库自控的概况。自控设置和运行状况很好的冷库虽然只有5座,占统计数的9,然而就是这些冷库代表了当今的潮流和方向。随着电子技术的发展,自控元件越来越先进、可变程序控制器(PLC)和微机的功能越来越强、自控程序越来越完善,系统优化和节能的意识也越来越强。冷库的节能和自动控制的关系越来越紧密,要把冷库的节能做好和做得更好,就必需把自动控制搞好和搞得更好。上述五座代表当今潮流和先进水平的冷库所采用的以下几项自控内容的实例对实现冷库节能都起了相当重要的作用。2 如何做好冷库节能的自动控制上述内容的基本出发点是以氨为制冷工质的集中式制冷系统的冷库,当今以卤代烃为制冷工质的分散式、准集中式、集中式制冷系统的冷库得到了很大的发展,其自控程度也往往高于以氨为制冷工质的集中式制冷系统冷库。多工质不同系统各类冷库的广泛应用,极大地丰富了冷库自动控制的内容,同时也为自动控制在冷库节能中的应用提供了广阔的用武之地。2.1 冷库节能的自动控制由谁来研究开发冷库节能的自动控制主要涉及的内容是节能控制程序的编制和自控元器件的选用。作为自控元器件的厂商、专业设计院或有能力的使用单位均可担当冷库节能自动控制的研究和开发。到目前为止厂商和设计院在该领域内均已有所建树。冷库节能的自动控制最好能由厂商和设计院共同研制开发(可以厂商为主,设计院配合),在使用单位的实施过程中完善定型并不断研发新产品。2.2 冷库节能自动控制具体项目的设计和实施配合一个具体项目节能自动控制的实施过程往往是通过设计、安装调试、试运行、效果考核並修正,直至符合设计要求达到节能目的为至。当项目要求内容有所变比时,可随时修改並满足要求。冷库的节能往往需要通先进的制冷改备、合适的系统匹配、灵话的应变措施和严格的运行管理得以实施,这就需要制冷技术人员在优化制冷工艺设计的基础上,熟悉节能需要、结合本项目特点,设计出完整的冷库节能自动控制流程图。根据自控流程图,电气自控技术人员才能完成其电气自控设计,同时还能运用其专业知识,使自控流程更为简化和优化。冷库节能是冷库自动控制重要组成部分,凡冷库自动控制均由制冷和电气两部分内容组成,只有在两方面技术人员的共同努力下才能使冷库自动控制行之有效並使冷库节能落到实处。冷库节能自动控制的试运行也是十分重要的一环,在试运行中应和使用单位和专业厂商保持密切联系,与使用单位探讨运行效果,与专业厂商商讨修正措施。3 冷库节能自动控制的若干做法和设想节能是冷库自动控制的目的之一。3.1 关于库房温度和蒸发温度调节3.1.1 多点温度参数的库房温度调节以往库房温度调节以位式调节为主,对蒸发温度往往不作调节,很难达到好的节能效果。库房温度理想的控制方式是以库房的平均温度、冷风机的进风及其出风温度为输入参数,编制适当的控制程序,通过PLC进行调节。如此温库调节可以达到节能的要求,也能满足某些库房高精度温度调节的需要,目前己可达到0.250C的精度要求节能约10。3.1.2 減少不同蒸发温度冷间的並联运行 由于同一系统的制冷压缩机只能在同一个蒸发温度下运行,所以不同蒸发温度的冷间如果並联运行,对于相对蒸发温度较高的冷间就处于不节能的运行状态,该冷间热负荷越高就越不节能。应当尽量避免这种情况的出现。氟利昂制冷系统中一机双温冷库的做法,在高温库回气管上加背压阀,在低温库回气管上加单向阀,是不节能的典型做法,不应提倡而宜废止。3.1.3 变蒸发温度调节在某一运行状态下如果蒸发温度能以库房热负荷以及制冷系统制冷量为参数进行调节,则既能达到节能的目的还能使能量调节更为合理。一般而言,制冷系统蒸发器和制冷压缩机的配备基本都能满足最高负荷的需要。如果冷间热负荷减少而制冷量不能及时作出相应调节,则制冷系统的蒸发温度将会相应降低,使压缩机的制冷量与热负荷达到一个新的平衡点。而蒸发温度的降低反过来却增加了蒸发器的制冷量,面对己减少的热负荷必然形成频繁启停的后果。蒸发温度每变化10C,相应增减的电能约35。如果及时调高蒸发温度,使系统在另一亇理想的平衡点上,则不但避免了浪弗、做到了节能,还减少了制冷压缩机的频繁起动,是一举两得的节能措施。3.1.4 变流量调节以往氨制冷系统蒸发器的制冷剂流量基本没有变流量调节;氟利昂系统蒸发器的制冷剂流量,大多数只做到简单的比例调节。空气冷却器的空气流量大多数没有调节或者只有双速及风扇台数调节。这两种流量参数的调节都是与库房冷分配设备制冷量以及库房温度直接相关的调节,也是冷库节能自控应于重视的内容之一。3.1.5 设定合适的控制精度和加设超限控制不同的库房、不同的库存商品和不同的贮存期都有不同的库房温度及其控制精度要求。从节能的角度出发,只要不影响商品的品质,库房温度宜取高不取低、控制精度宜取低不取高,不必偏面追求过低的库温和高精度控制。对于多亇冷间的库房温度控制,除了原有的库房温度设定值之外,宜加设库温超限控制值。这种双因素的库房温度调节能做到制冷系统需要投入运行时,不会因为亇别库房温度的偏离而过早投入运行;还可以根据当时的实际情况不使冷间或制冷系统过早地仃止运行,充分利用现有能量並避免设备或系统的频繁启停。3.1.6 设置避高峯运行控制电力紧缺是当前全国各地存在的普遍现象,用电峯谷的巨差更加重了电力紧缺,为此电费的峯谷差价在许多城市实行而且价差还在逐步拉大。在不影响商品质量的前提下,冷库设置避高峯运行,有利于电网削峯补谷,宏观上帮助全局节能;微观而言也有利于降低冷库的运行成本。3.2 冷间相对湿度调节冷间相对湿度的调节与温度调节方法的相似之处不必重复叙述。一般冷间的相对湿度在8595之间,但也有一些冷间要求的相对湿度低于或高于该范围,例如有些气调库要求的相对湿度是98、而有些农作物种质库的相对湿度要求是4045。在高相对湿度调节和低相对湿度调节时尤因注重节能措施。3.2.1 高相对湿度调节对于高相对湿度要求冷间的调节,首先要尽量降低制冷剂温度和库房温度之间的对数平均温差(可取2K),有必要时还可采用载冷剂间接制冷系统;此外还可采用空气融霜並把融霜水还原给库房。这两项措施通过自动控制予以实施,是行之有效的节能方法,国内贸易部没计研究院设计的龙口二万吨气调库就是一亇很好的例证。3.2.2 低相对湿度调节对于低相对湿度要求冷间的调节,主要也应做好两方面的控制。其一是在选用尽量少带热量进冷间的去湿方法和去湿机的基础上,控制好去湿程序,在达到相对湿度要求的同时減少冷间的热负荷。其二是避免气流组织控制时带入不必要的室外热湿负荷;曾经有一亇低温低湿的农作物种质库,由室外侵入库内的热湿负荷约占原计祘负荷的35左右。3.3 关于供液方式调节直接膨胀供液是大多数卤代烃(包括氟利昂)系统和个别氨系统采用的供液方法。这种供液方法以往基本采用热力膨胀阀供液,由于选型、调节以及产品本身的问题,无法实现节能的目的。电子膨胀阀的出现结合多点温度参数的库温调节,可以较好地实现节能运行,一般可节能10。卤代烃制冷系统的热力膨胀阀产品已相当成熟而且还有专用的PLC库温控制器,但由于种种原因在冷库制冷系统中尚未普遍采用,有待加力推广。氨制冷系统蒸发器运行的过热度不大,控制难度相对较大,目前尚无成熟的氨用电子膨脹阀产品。9
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