降膜蒸發(fā)器

概述：

由于具有傳熱系數(shù)，適應(yīng)溫差小，高真空蒸發(fā)的特點(diǎn)，可廣泛利用低品質(zhì)廢熱(如干燥機(jī)熱空氣及煙道氣)，余熱冷凝水，過程水及其閃蒸汽)組成廢熱蒸發(fā)機(jī)組可少用或不用新鮮蒸汽而完成濃縮任務(wù)。具有傳熱效能高，溫差小，無液柱引起的沸點(diǎn)損失、動力消耗少的優(yōu)點(diǎn)。在降膜蒸發(fā)系統(tǒng)中，物料呈膜狀覆蓋整個換熱管內(nèi)壁，沿?fù)Q熱管向下流動同時蒸發(fā)。即使在蒸發(fā)溫差較低的情況下仍有可能獲得較高的傳熱系數(shù)。換熱管中部充滿物料蒸發(fā)形成的二次蒸氣，設(shè)計(jì)中可以根據(jù)情況，選擇二次蒸汽與物料在換熱管中同向或逆向流動。離開換熱管的二次蒸汽然后進(jìn)入分離器完成汽液分離。分離器可采用常規(guī)的離心式或沖擊式可以設(shè)計(jì)為獨(dú)立于降膜加熱器的分體式，也可以是與加熱器集成的一體式。一體式的設(shè)計(jì)可以縮小占地空間，降低安裝成本。蒸發(fā)有輕微結(jié)垢問題的物料需要采用循環(huán)茶發(fā);即使物料循環(huán)，采用降設(shè)計(jì)也比強(qiáng)制循環(huán)節(jié)能很多。熱敏的物料可采用直流程降膜設(shè)計(jì)以縮短物料停留時間，同時降低的能耗。膜發(fā)系統(tǒng)適用于處理沒有結(jié)垢問題或結(jié)垢系數(shù)低的物料，通常不能用來結(jié)品。但根據(jù)蒸發(fā)物料的特性，可以在設(shè)計(jì)中合并降膜與強(qiáng)制循環(huán)兩種形式，用于處理有結(jié)垢問題的物料和連續(xù)結(jié)品系統(tǒng)。在MVR(機(jī)械蒸汽壓縮)和TVR(蒸汽動力熱泵)設(shè)計(jì)中，低蒸發(fā)溫差可以降低電耗和蒸汽消耗，降膜設(shè)計(jì)可以用于蒸發(fā)溫差較低的情況，所以較適用于這類設(shè)計(jì)。受物料本身特性的影響或采用低溫廢熱蒸發(fā)時(例如管束尾氣或液化閃蒸汽)，蒸發(fā)器內(nèi)物料溫度受到限制，與升膜相比采用降膜設(shè)計(jì)可放入更多效以降低能耗。降膜系統(tǒng)普遍應(yīng)用于食品，制藥，化工，造紙/制漿，和煤化工等行業(yè)。

Because of the characteristics of heat transter coefficient,small temperature difference and high vacuum evaporation, low-qualit waste heat (such as dryer hot air and flue gas) can be widely used, and waste heat (condensed water. process water and its flash steam) can be used to form a waste heat evaporation unit,which can complete the concentration task with little or no fresh steam. It has the advantages of high heat transfer efficiency,small temperature difference,no boiling point loss caused by liquid column and less power consumption. In the falling film evaporation system, the material covers the inner wall of the whole heat exchange tube in the form of a film, and flows downward along the heat exchange tube while evaporating. Even if the evaporation temperature difference is low, it is stil possible to obtain a higher heat transfer coefficient,The middle part of the heat exchange tube is filled with secondary steam formed by evaporation of materials. and the secondary steam and materials can be selected to flow in the same direction or in the opposite direction in the design according to the situation.The secondary steam leaving the heat exchange tube then enters the separator to complete vapor-liquid separation. The separator can adopt conventional centrifugal or impact type; It can be designed as a separate type independent of the falling film heater,or it can be integrated with the heater.The integrated design can reduce the floor space and the installation cost. Evaporation of materials with slight scaling problems requires cyclic evaporation Even if the material circulates, the falling film design is much more energy-saving than forced circulation,For heat-sensitive materials, straight-flow falling film desian can be used to shorten the residence time of materials and reduce the eneray consumption of pumps. Falling film evaporation system is suitable for treating materials with no scaling problem or low scaling coefficient, and usually cannot be used for crystallization,However,according to the characteristics of evaporated materials, falling film and forced circulation can be combined in the design to deal with materials with scaling problems and continuous crystallization systems. In MVR (mechanical vapor compression)ａnd TVR (steam driven heat pump) designs, low evaporation temperature difference can reduce power consumotion and steam consumption. and falling film desian can be used in the case of low evaporation tomperature difference. so it is more suitable for this kind of desian. The maximum material temperature in the evaporator is limited by the characteristics of the material itself or when low-temperature waste heat evaporation is used (such as tube bundle tail aas or liauefied flash steam).Compared with the falling film design,more efficiency can be put in to reduce eneray consumption.Falling film svstems are widelv used in food pharmaceuticalchemical.paper/pulpａnd coal chemical industries.

特點(diǎn)：
1、適用于濃度低，含固量少，結(jié)垢傾向較低的物料;
2、適用于熱敏性物料，傳熱系數(shù)高;
3、溫差小，真空蒸發(fā)，保證物料管路足夠的液狀膜，避免干辟，結(jié)垢現(xiàn)象:
4、無液柱壓力引起的沸點(diǎn)溫差損失，溫差損失小，循環(huán)量少，動力消耗少。
1.Suitable for materials with low concentration, low solid content and low scaling tendency:
2.It is suitable for heat-sensitive materials with high heat transfer coefficient:
3. The temperature difference is small, and vacuum evaporation ensures enough liquid film in the material pipeline to avoid dry wall and scaling;
4.There is no loss of boiling point temperature difference caused by liquid colun pressure, and the loss of teperature difference is small with less circulation and less power consumption.

技術(shù)參數(shù)：