The level is maintained in the upper portion of the tubes or above the top tubesheet, and the circulation pattern is up through the tubes and down through a central pipe called a downcomer. Zero discharge system plant mee,multi effect evaporator. Best product quality due to gentle evaporation, mostly under vacuum, and extremely short residence times in the falling film evaporator. The multipleeffect evaporator was invented by the africanamerican engineer norbert.
Configuration screen of multipleeffect evaporation visualbasic application. Multipleeffect distillation or multieffect distillation med is a distillation process often used for sea water desalination. The milk is pumped from a balance tank 1 to the pasteurizer 2, where it is pasteurized and heated to a temperature slightly above the boiling point of the first evaporator effect. A straight, steamheated, tripleeffect falling film evaporator processing whey would require at 270 lbhr, 90 degrees f water at 31,5 galmin, and 163 ft. Heating is performed by passing steam inside the tube bundle. A simple unit, not used to a great extent on new installations, is the horizontal tube evaporator.
Steam enters a chest on the end of the tubes, moves through the tubes and the condensate is. In indirect heating, the heat, generally provided by the condensation of steam, passes through the heating surface of the evaporator. Evaporator in a cooling system in which the liquid evaporates and this order is refrigerant device that extracts heat from its environment. The latent heat of the vapor leaving in single effect evaporator is not used but is discarded. The number of effects in a multiple effect evaporator is usually restricted to seven because after that, the equipment cost approaches the cost savings of the energyrequirement. Some of the problems arising during evaporation include. Multiple effect evaporator working principle multiple effect evaporator is the combination of several sets single effect evaporator. Jun 17, 2016 evaporator operating principle can summarize briefly as follows. Evaporator operating principle can summarize briefly as follows. A the value of thermal decompression can be seen with a comparison of multipleeffect evaporation by itself to multipleeffect evaporation with thermal decompression. Consider two evaporators connected so that the vapour line from one is connected to the steam chest of the other as shown in fig.
In case of multipleeffect evaporation plants, the exhaust vapors from the product are used to heat the downstreamarranged evaporation effect so. In essence, the steam usage for the double effect with thermal recompression is comparable to that of a triple effect evaporator. We define the evaporation process as one that starts with a liquid. Our objective is to save your operating and disposal costs. Vapors obtained from first effect act as a heating medium for another effect. In a multiple effect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. Swenson thermal vapor recompression tvr evaporators use a thermocompressor to reduce the steam required per pound of evaporation. Welcome to the world of agitated thin film dryer atfd and other heat transfer equipment. Its divided in to three category on the basis of feed direction. Pdf design of heat integrated multiple effect evaporator. Scrapped surfacethin film evaporators are designed for evaporation of highly viscous and sticky products, which cannot be otherwise evaporated. The milk is pumped from a balance tank 1 to the pasteurizer 2, where it is pasteurized and heated to a temperature slightly above.
Using a thermocompressor together with a multipleeffect unit optimizes the energy balance. Scribd is the worlds largest social reading and publishing site. The multipleeffect configuration combines two or more evaporator bodies to conserve steam, which is condensed in the firsteffect heat exchanger only. This method of evaporation in series is called multiple effect evaporation, and each stage is called an effect. The encon mechanical vapor recompression mvr evaporation process involves our forced circulation flash evaporator utilizing mechanical vapor compression. Design principles of single effect and triple effect evaporators by. The single effect evaporator uses rather more than 1 kg of steam to evaporate 1 kg of water. Evaporation is an operation used to remove a liquid from a solution, suspension, or emulsion by boiling off some of the liquid. Because the boiling temperature of water decreases as pressure decreases, the vapor boiled off in one vessel can be used to heat the next, and only the first vessel at the highest pressure. In each stage the feed water is heated by steam in tubes, usually by spraying saline water onto th. The kraft process consists of multiple effect evaporators mee system as one. Multiple effect evaporator is used for steam economy. Multipleeffect evaporators if the water vapor from the first effect of a multipleeffect evaporator can be introduced into the steam chest of a second effect operating at a lower boiling point, the latent heat in the water vapor can be reused. Thermal vapor recompression tvr evaporator swenson.
The purpose of this article is to investigate the influence of using feed water preheaters in multiple effect distillation systems with thermal vapor compression medtvc. In a multipleeffect evaporator, vapor from one body heats a second body at a lower boiling. Possible methods to solve multiple effect problems several approaches can be used to solve the typical multiple effect evaporator homework problem. Multiple effect evaporator is the combination of several sets single effect evaporator. In any evaporation operation, the major process cost is the steam consumed. Noniterative design of multiple effect evaporators using excel addins. A multieffect vacuum evaporator consists of a set of interconnected evaporators where the first effect is the first evaporator, and so on. By increasing the number of effects we can increase the economy of an evaporator system.
The number of effects in a multipleeffect evaporator is usually restricted to seven because after that, the equipment cost approaches the cost savings of the energyrequirement. In a multiple effect evaporator the vapour from one evaporator is fed into the steam chest of the other evaporator. Vacuum evaporation with steam or hot water by multiple effect. In the operation of a single effect evaporator the liquid feed passes once through heating tubes, steam emerges and leaves a liquid concentrate. Thermal vapor recompression tvr evaporator swenson technology. In the operation of a single effect evaporator the liquid feed passes once through. The amount of steam consumption in multiple effect evaporators is already mentioned in lesson 4. Multiple effect evaporatorpptx free download as powerpoint presentation ppt pptx, pdf file pdf, text file txt or view presentation slides online scribd is process modelling and optimization of design parameters in. High energy efficiency due to multipleeffect arrangement or heating by thermal or mechanical vapor recompressor, based upon the lowest theoretical temperature difference. Much of this latent heat, however, can be recovered and reused by employing a multiple effect evaporator, that is, vapor from one effect serves as the. This causes a gradual increase in the resistance to heat transfer and, if the same temperature difference is maintained, the rate of evaporation decreases with time. The falling film evaporator has two main configurations, which includes the horizontal and the vertical tube,the horizontal tube is the most common design used in the desalination industry. Pdf detailed design of a single effect evaporator with. Efficiency is gained by using multiple effect systems.
This design provides improved steam economy with less costly equipment than straight steam heated designs but requires higher pressure steam. Evaporator operation in evaporation, solids may come out of solution and form a deposit or scale on the heat transfer surfaces. Feb 22, 2017 working principle of a falling film evaporator. Falling film evaporator working principle duration. Construction and working of single effect evaporator pdf. Design and simulation of a multipleeffect evaporator using. Optimization of a multiple effect evaporator system. It is paramount the for this process minimal wetting rate is achieved.
Evaporator types and principle of operation installation. Evaporation is an operation used to remove a liquid from a solution. The first effect of a multiple effect evaporator is the effect to which the raw steam is fed. This is the principle working behind vacuum evaporators. Direct heating is represented by solar evaporation and by submerged combustion of a fuel. Zero discharge system consists of a combination of multiple effect evaporators mee followed by a sludge dryer we offers mee systems with a stripper, thermo compressor and axial flow pump. Evaporation is the unit operation by which solvent is evaporated from the solution by. The characteristic is to heat the next effect evaporator by used steam produced from the front effect, so as to reduce energy consumption. All textbooks 3,4,5 that cover evaporation present a pencilandpaper iterative approach. Single effect trc thermal vapor recompression diagram. Ketav consultant leads by virtue of superior engineering design capabilities, manufacturing excellence and a project based approach committed to to deliver high performance total evaporation solution customized to our client. The basis of vacuum evaporation environmental engineering.
The process inside and andritz evaporator relies on a free flow falling film of liquor over the surface of the lamella. In vapor recompression method, vapor from the evaporator is compressed to increase its temperature so that it will condensate at temperature higher enough to permit its use as a heating media in the same evaporator. The calandria evaporator has a heat exchanger with tubes usually less than six feet long integral with the vapor body. Several approaches can be used to solve the typical multiple effect evaporator homework problem.
Using a thermocompressor together with a multiple effect unit optimizes the energy balance. Mvr evaporator with finisher if elevation of boiling point gets significant, multiple pass evaporators and finishers provided with an additional recompressor working in series to the main recompressor are employed. Unlike singlestage evaporators, these evaporators can be made of up to seven evaporator stages or effects. A multipleeffect evaporator is an apparatus for efficiently using the heat from steam to evaporate water. Construction and working of single effect evaporator pdf download. Evaporation is a standard thermally driven unit operation.
Multiple effect distillation or multi effect distillation med is a distillation process often used for sea water desalination. The process fluid to be vaporized is feed to the evaporator at the top of the tube sheet. Finisher with two additional recompressors in series with the main recompressor. In multieffect falling film evaporators the vapour produced is used in order to heat a so called second effect on a lower. Economics and product characteristics determine the suitability of thermal vapor recompression operation. A suitable distribution unit is nessecary in order to achieve an even liquid distribution. Food processing evaporator systems pacific gas and. Design and simulation of a multiple effect evaporator system. A multipleeffect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water.
The vertical tube falling film function describes are under. Sep 04, 2015 overview of a multiple effect evaporators. Agitated thin flim dryer atfd agitated thin film dryer. Suitable evaporating process for material with high viscosity and concentration, surface film flow with minimum losses no need of vapor condenser, simple process, reliable continues operation due to the film flow in the one. This type of evaporators have been specially designed to provide high degree of agitation, effecting heat transfer as well as scrapping the walls of the evaporator to prevent deposition.
Mauhay, romariz morquianos, almira belle nopre, frederick group iii che5102 outline introduction multiple effect evaporator working principle uses advantages and disadvantages. In the present work, we first show that the subsystem of heat transfer equations can be solved. In a multipleeffect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. A heatsavingpercent equation can be used to estimate how much one will save by adding a certain number of effects. In the evaporator, the seawater fed in is heated to its boiling temperature and is partly evaporated by boiling. Calculations on evaporators can be carried out combining mass and energy balances with the principles of heat transfer. Multipleeffect vacuum evaporators condorchem envitech. Milk condensing in vacuum pan uses high amount of steam to evaporate water. The double effect evaporator with thermal recompression requires 33% less steam than the conventional double effect. Noniterative design of multiple effect evaporators using. In such a system, the heat from the original steam fed into the system is reused in. By using this design, the encon mvc evaporator allows for minimal scaling, maximum uptime, and low operating costs. Similarly, highertemperature vapor driven out of the product in one effect is used to heat lowertemperature product in another. In general the process liquid flows at the tue inside.
An evaluation and redesign of a thermal compression evaporator a thesis submitted to the graduate faculty of the university of new orleans in partial fulfillment of the. Definition evaporation is the process used to concentrate a solution by removing the solvent mainly water in a purified form by the application of heat. It is thus a thermal separation, or thermal concentration, process. Horizontal tubes from 2 to 3 cm diameter extended across the bottom of a cylindrical chamber from one to three meters in diameter and 2. Plate heat exchanger, how it works working principle hvac industrial engineering phx heat transfer duration. Multiple effect evaporator principle vapor produced in one effect evaporator is used as heating medium in next effect evaporator this reduces total energy requirement required t between steamvapor and product is created by progressively decreasing boiling point of the solution in each effect by lowering pressure. However, the coefficients in the equations depend on the unknowns through.
In each stage the feed water is heated by steam in tubes, usually by spraying saline water onto them. Using a multiple effect evaporator, the operation is based on the steam produced in one effect being used as the heat source for the following effect. Mvr falling film evaporator mechanical vapor recompressionmvr evaporator main applications. Evaporation is the unit operation by which solvent is evaporated from the solution by boiling. This method of evaporation in series is called multipleeffect evaporation, and each stage is called an effect. Methods of feeding forward feed backward feed mixed feed parallel feed. For example, if steam is available at 220f 104c, then the last effect boiling temperature is 120f 49c. Ketav consultant leads by virtue of superior engineering design capabilities, manufacturing excellence and a project based approach committed to to deliver high performance total evaporation solution customized to our client requirement.
In the present work seven effect evaporator system of typical indian. A multiple effect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water. In principle, these equations should be relatively easy to age 14. This means that, in principle, the boiling temperature decreases, thus allowing the vapor generated in an evaporator or effect to be used as heating fluid in the following effect. The chief factor influencing the economy of an evaporator system is the number of effects. To reduce energy consumption, water vapor from an evaporator is entrained and compressed with high pressure steam in a thermocompressor so it can be condensed in the evaporator heat exchanger. In the operation of a single effect evaporator the liquid. In the evaporator, the seawater fed in is heated to its boiling temperature and is partly. Pdf a simplified and generalized method to size multipleeffect. The stripper is part of the multipleeffect evaporator system. Suitable evaporating process for material with high viscosity and concentration, surface film flow with minimum losses no need of vapor condenser, simple process, reliable continues operation due to the film flow in the oneway evaporator, heat transfer. Multi effect evaporator multiple effect evaporation remains one of the popular methods used for the concentration of aqueous solutions. The heating steam loses its latent heat and condenses before it flows out of the tube bundle. In case of multiple effect evaporation plants, the exhaust vapors from the product are used to heat the downstreamarranged evaporation effect so that the steam consumption will be reduced accordingly.
1128 764 184 1156 407 251 804 240 1113 1535 542 75 1120 896 180 1015 653 1164 572 633 223 685 321 1105 825 1469 1018 735 1337 152 180 696 133 633 11 574