Falling film evaporator gea engineering for a better world. Liquid distribution and falling film wetting in dairy. In this paper, the liquid distributor performance for the falling film evaporation process was tested, and the relationship between the liquid height and flow rate were studied in the experiment. Jun 20, 2017 the evaporator 12 further includes a plurality of modular liquid distributors 40 in operative association with the plurality of tube bundles 20 of the falling film evaporator 30. Via a liquid distribution system, the product enters the tubes where it forms a film along the inside wall. In this paper, the mathematical model of the refrigerant flow in the curly top surface structure of distributor was established and the model was studied using numerical. Upward vapour flows in falling film evaporators and. Falling film evaporators what you need to know aptia.
However, falling film evaporators must be designed very carefully for each operating condition. Evaporators energy efficiency of evaporator manufacturer. The heat transfer area is the key parameter in designing of an evaporator and many correlations are available to estimate the size of. The liquid distributor is the most critical component in any fallingfilm evaporator. Its ease of operation and timeefficiency makes it one of the most widely used evaporators.
Heat transeer performance of falling film type platefin evaporator junichi ohara abstract. Experimental investigation on the liquid distributor. Heat transeer performance of falling film type platefin. A falling film evaporator comprises a vertical shellandtube heat exchanger calendria with a liquid distributor unit and a vapour liquid separator.
Ive experienced similar problems on a waste water falling film evaporator with circulation on the effects. A falling film evaporator includes a plurality of evaporator tubes through which a volume of thermal energy transfer medium is flowed, and a distributor to distribute a flow of liquid refrigerant over the plurality of evaporator tubes. Experimental study on the liquid distributor of horizontal tube. The high performance evaporators are important for process industries such as food, desalination and refineries. Evaporator and liquid distributor carrier corporation. Given that an evaporator is a heat exchanger, it is often incorrectly assumed.
The liquid falling on distributor get distributed in such a way that it flow down as a thin film on inside surface of the tube. A calandria liquid distributor device was designed for horizontal falling film evaporation. When the exchanger is large or the liquid is highly viscous, a more complex and expensive distribution system such as direct placement is needed. For complete wetting it is important that a suitable distribution system is selected for the head of the falling film evaporator. A falling film evaporator is a type of solvent recovery system. Evaporator liquid distribution has received relatively little research but it has been shown that the efficiency of evaporation reduces when there is poor wetting. Us3412778a us58907066a us3412778a us 3412778 a us3412778 a us 3412778a us 58907066 a us58907066 a us 58907066a us 3412778 a us3412778 a us 3412778a authority us united states prior art keywords product evaporator falling film film evaporator plate prior art date 19661024 legal status the legal status is an assumption and is not a legal conclusion. It also reduces any additional effluent generation stemming from cip, as well as the treatment costs involved. Individual tubes must be wetted evenly around their circumference. Establishment of the falling film evaporation model and. Under the action of gravity and vacuum induction and airflow, it becomes a uniform film. Typical tema types are bem, nen or a combination of the two. A falling film evaporator ffe is a combination of vertical shell and tube heat exchanger and vapor liquid separator mounted at bottom.
The distributor then delivers the liquid to the tube sheet. It is an extension of the falling film evaporator, and has application in any field where the liquid to be evaporated cannot withstand extended exposure to high temperatures, such as the concentration of. Wetting rates are increased by using longer heating tubes, dividing the falling film evaporator into several compartments or by recirculating the product. Falling film evaporators offer distinct operating advantages in the concentration of many materials, such as certain food products, fruit juices, pharmaceuticals and similar materials, which are particularly suited to evaporation in this type of equipment. Vapour in some passes flowed upwards instead of downwards. Liquid distribution and falling film wetting in dairy evaporators. The falling film evaporators have many advantages over flooded and vertical tubes that make them best candidate for processes industries application. The importance of uniform feed distribution cannot be overemphasized. These, in essence, are the same as the falling film evaporators we described above, except that the liquid solvent is introduced not at the head or top of the evaporator, but at the bottom. Liquid distribution is through distributor plates placed at top of calandria. In a falling film evaporator, poor liquid distribution can cause inefficient heat transfer and tube plugging problems. The guide plate was introduced in this, which is easy to manufacture.
In falling film evaporators uniform distribution of liquid in each tube is the most important feature for efficient performance. The distributor is the key component in the falling film evaporator, which determines the uniformity of the distribution of the refrigerant in the falling film evaporator. Instead they just go into the flow through the tubes. Wo2008010237a1 improved distributor for falling film. Design of industrial falling film evaporators intechopen. Rising falling film tubular evaporators thermal kinetics. Significant interaction between vapour and liquid flows is predicted. Nov 20, 2019 what exactly is a falling film evaporator. The liquid forms a film along the inside of the tubes. One of our dairy customers wanted to produce a new product on their existing falling film evaporator. The minimum wetting rates of three different milks were found in a model evaporator tube under isothermal, heat transfer and evaporation conditions at 60. This directional change helps separate liquid from a primarily.
Falling film screw chiller, find complete details about falling film screw chiller, falling film screw chiller, falling film evaporator, liquid distributor from chilling equipment supplier or manufacturerzhejiang kingfit enviroment co. The distributor is the key component in the fallingfilm evaporator, which determines the. The results showed that the liquid height of liquid distributor is proportional to flow, liquid distributing hole diameter and flow, but inversely. The efficiency of falling film evaporator entirely depends on designing an effective distributor unit that dispenses the liquid uniformly across the tubes, so that there is a continuous flow forming a consistent film along the tubes. The liquid distributor is the most critical component in any falling film evaporator.
Feb 22, 2017 working principle of a falling film evaporator. Lueffects of liquid distribution method on fallingfilm mode. The thickness distribution, velocity distribution and temperature distribution of the liquid film inside and outside the tube were obtained by numerical simulation. Previous experience with similar services remains the best guide. The typical components of a falling film evaporator. The optimized design of the liquid distributor helps prolong uptime and reduce cip costs.
Hot vapors condense on the outside tube walls, releasing heat that is transferred to the fluid. Falling film evaporators have a number of advantages over their flooded evaporator counterparts. Alfa lavals filmvap evaporation systems are based on tubular falling film principle. The guide plate was introduced in this, which is easy to manufacture and can effectively reduce splash phenomenon. Alfa laval filmvap tubular fallingfilm evaporators are well proven and. The utility model relates to an evaporation equipment part, in particular to a liquid distributer of a falling film evaporator, which is provided with a tube plate. In the heating tube, tiny films enter through a distributor connected at the top of evaporator. In the first stage, process liquid enters the falling film evaporator through the inlet feed pipe and is directed to the top liquid distributor.
Distribution pan fouling in a falling film evaporator. In falling film evaporators, liquid and vapors flow downwards in parallel flow. The incorporation of vapour tubes in distributor plates eliminated the problem. Due to the uniquely designed liquid distributors they can handle juices with high suspended solids contents and with tartrate. The characteristics of heat transfer and flow patterns are investigated experimentally for the vertical falling film evaporation of pure refrigerant hcfc123 in a rectangular minichannels consisting of offset strip fins. The evaporator is a special type of heat exchanger. The process liquid is pumped into the top of the falling film evaporator and is distributed evenly across all of the heating tubes in the heat exchanger. Distribution pan fouling in a falling film evaporator glm hydro. The fluid distributor has to be designed carefully in order to maintain an even liquid distribution for all tubes along which the solution falls. Falling film evaporators are widely used for the concentration of liquid foods, especially milk prior to spray drying. A falling film evaporator is an industrial device to concentrate solutions, especially with heat sensitive components. Both rising and falling film evaporators are susceptible to tube coating in the heat exchanger which reduces heat. An internal distributor ensures the tubes are equally wetted. In general evaporation takes place inside vertical tubes, but there are also applications where the process fluid evaporates on the outside of horizontal or vertical tubes.
In falling film evaporators, the liquid product usually enters the evaporator at the head of the evaporator. They require a lower charge, as the entire shell in the case of horizontal evaporators or all the tubes in the case of a vertical evaporator need not be filled with liquid as a thin film is now used to cover the surfaces. The distribution of the refrigerant has a significant influence on the performance of the falling film evaporator. The liquid to be concentrated is preheated to boiling temperature if required. Essentially, it is a system that uses a vacuum to lower the boiling point of the solvent solution, vaporizes it with the use of a heating source, and then turns it back into a liquid form at cooling condensers.
Home products evaporation equipment rising falling film tubular evaporators. A distributor for falling film evaporator comprising of. The falling film evaporator consists of shell and tube heat exchanger called as calandria that is mounted in vertical position. May 05, 2016 a falling film evaporator includes a plurality of evaporator tubes through which a volume of thermal energy transfer medium is flowed, and a distributor to distribute a flow of liquid refrigerant over. Some estimates were available from previous work for the minimum flowrates required to obtain a complete falling film inside a tube. Falling film evaporator manufacturer,falling film evaporator. These evaporators have long tubes and are most suitable for low temperature applications. Typical falling film saline water evaporators produce water vapour from a thin film of saline water flowing down. A climbing falling film plate evaporator is a specialized type of evaporator in which a thin film of liquid is passed over a rising and falling plate to allow the evaporation process to occur. The feed to the ffe is superheated and a flash evaporation occurs in the head of the ffe. The rising falling film concentrator rfc provides easy unrestricted liquid distribution, eliminates long circulation piping, and either reduces overall head room requirements or reduced circulation rates. An even thin film enters the heating tubes via a distribution device in the head of the evaporator, flows downward at boiling temperature, and is partially evaporated. Falling film evaporator works on the principle of liquid spreading into every tube, hence creating a tiny film all over the tubes area.
In falling film evaporators uniform distribution of liquid in each tube is the most important feature for. The optimum design of fallingfilm evaporator and numerical. This paper studies the liquid distribution from the relation between distributive unwelldistributed coefficient and liquid flux of distributor tube and distributor hole. The liquid enters the heating tube and forms a thin film on the tube wall where it flows downwards at boiling temperature and is partially evaporated. The compact evaporator operates by the simple falling film principle, in which fluid is pumped into the top of each heater through a liquid distributor and flows down the inside of each tube as a thin liquid film.
A wide variety of liquid evaporator options are available to you, there are 975 suppliers who sells liquid evaporator on, mainly located in asia. Milk enters the evaporator at the top and flows onto a distributor. Optimization of the liquid distributor in a falling film evaporator by. Climbing and falling film plate evaporator wikipedia. Each liquid distributor has at least one inlet 32 for receiving liquid refrigerant, or a mix of liquid and vapor refrigerant, passing through the liquid inlet 15. Equal, uniform distribution of liquid to all tubes is paramount in order to operate as designed. Short processing time, low heat impact and sophisticated hygienic design predestinated the evaporators for the concentration of all kinds of fruit juices, e. Our distribution is a twostage system, featuring high accuracy and a wide operating range. Falling film evaporator falling film evaporator manufacturer.
Many tasks were performed to assess the performance of the liquid distribution systems. Cn201949666u liquid distributer of falling film evaporator. The liquid to be concentrated is supplied to the top of the heating tubes and distributed in such a way as to flow down the inside of the tube walls as a thin film. Falling film vacuum evaporation is a very efficient technology for obtaining high quality water from an effluent with a high contaminant concentration. During cip the calcium flakes get a chance to dissolve in the acid along the way without the danger of clogging a distribution pan. The dry patches may be caused by a liquid flowrate insufficient to maintain a continuous liquid film or by the evaporators not being exactly vertical. In most cases, steam is used for heating the evaporator.
The feed to the ffe is superheated and a flash evaporation. Various strategies exists in order to achieve an even liquid distribution over the entire tube sheet. Us3412778a liquid distributor for tubular internal. Vapour flows in multipass falling film evaporators were modelled.
Liquid to be boiled enters at the top of the exchanger. Evaporation takes place on the surface of the falling liquid film. The major problem with falling film evaporators is nonuniform distribution of the feed liquor as a film inside the tubes. The calculation formula of the overall heat transfer coefficient of the falling film evaporator was obtained and verified by experiments. Flow distributor and baffle system for a falling film evaporator. Our proprietary distribution system is the essential part of our falling film evaporator 3d model of a falling film evaporator design our feed distributor is a two stage system, with a highly accurate performance and a wide operating range. A falling film evaporator includes a flow distributor for uniformly distributing a.
It is very important that the liquid be well distributed so that it evenly flows down the inside walls of each tube. The complete range 7 product feed tube sheet steam tube wall vapour liquid film condensate film condensate tube sheet product feed the liquid distributor is the most critical component in any falling film evaporator. Experimental study on the liquid distributor of horizontal. Additionally, there are also climbing film evaporators or climbing film plate evaporators. Falling film evaporator ffe evaporator concept process. Falling film vacuum evaporators condorchem envitech. Liquid coolant in the form of thin film has a significant potential utility in high heat absorbing capacity that includes the heat of vaporization gantchev, 1987. Your process liquid feed enters the falling film evaporator through the inlet feed pipe. Uneven distribution leads to fouling and greatly reduces the efficiency of the evaporator. It is itself equipped with many drip points to ensure the generation of an even and calm static liquid height outside the tubes. The major difference between a typical shell and tube heat exchanger and a falling film evaporator is the liquid distribution at the top of the unit. Then it moves downwards at the boiling temperature that causes it to evaporate partially. Falling film evaporation is to add the material liquid from the upper box of the heating chamber of the falling film evaporator, and evenly distribute it into each heat exchange tube through the liquid distribution and film forming device.
Reduction of fouling in fallingfilm evaporators by design. Lacking that, manufacturers of falling film evaporator equipment should be consulted. Falling film evaporators are vertical shell and tube heat exchangers. The feed enters through tubes and flows downwards under the gravity while the heat is provided through the heating medium generally steam to ensure high heattransfer coefficient. The results showed that the liquid height of liquid distributor is proportional to flow, liquid distributing hole diameter and flow, but inversely proportional to liquid distribution aperture.1313 234 902 34 637 1066 97 654 1137 1181 9 929 166 554 1465 1205 1167 776 215 1277 605 1462 1043 67 1069 982 421 556 108 1412 480 690 496