In a multipleeffect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. Figure 4 shows the mass flows in a three effect evaporator. This arrangement of reusing vapor latent heat is called multiple effect evaporation. The utility model discloses a multiple effect evaporation waste water treatment system which comprises at least seven effect evaporators in series connection, wherein an air outlet of each effect evaporator is connected with a separator, an air outlet of each effect separator is connected with a. For a multiple effect evaporator system calculations, the values required to be obtained are. In a single effect evaporator, steam provides energy for vaporization and the vapor product is condensed and removed from the system.
The steam consumption of the evaporator unit can be. Typically, multiple effect evaporator calculations require an iterative solution procedure because so many of the required properties, etc. With our multiple effect evaporators, some effects can be shutoff in such a way that a triple or a double effect can be converted into a simple effect. 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. Article views are the countercompliant sum of full text article downloads since november 2008 both pdf and html across all institutions and individuals. This method of reverse feed is advantageous when the fresh feed is cold, since a. We do this in excel by using the solver function and a free addin that automates steam table lookups. Detailed design of a single effect evaporator with thermal vapor re compression thesis pdf available. The design of an evaporation unit requires the practical application of. The problems associated with a multiple effect evaporator system are that it is an energy intensive system and therefore any measure to reduce the energy consumption by reducing the steam consumption will help in improving the profitability of the plant. Unesco eolss sample chapters thermal desalination processes vol. Multiple effect evaporator evaporation boiling free 30. Calculation for multiple effect evaporator evaporation heat transfer. The characteristic is to heat the next effect evaporator by used steam produced from the front effect, so as to reduce energy consumption.
Investigation of multiple effect evaporator design. Triple effect evaporator engineering spreadsheets engtips. Fortunately, the overall approach is basically the same for the majority of problems, requiring only minor adjustments to compensate for problem quirks. Multiple effect evaporators can remove much larger amounts of solvent than is possible in a single effect. As a side benefit, teaching multiple effect evaporation allow s the opportunity to. The example from acm involves double effect evaporators and the procedure.
Evaporators are classified by the number of effects. It must be admitted, however, that the present method is also one of the approximate calculations, because it comprizes errors on drawing and the assumption that the heat requirement in the first effect of the n effects evaporator is 1n of that of the single effect evaporator, having the same amount of product liquor as that of the n effects. Koko, 1987 for the design of multiple effect evaporator systems with backward feed is simplified and generalized for any liquid flow feed arrangement. Outlining features of various evaporator configurations2. In a multiple effect arrangement, the latent heat of the vapor product off of an effect is used to heat the following effect. Modular simulation model for falling film evaporators with novel approach to manage dominant timevarying transport delays. Single effect evaporator can be wasteful of energy if the vapors heat is not used. Effects are thus numbered beginning with the one heated by steam. It takes a large amount of energy to boil off water from a solution. Calculations on evaporators can be carried out combining mass and energy balances with the principles of heat transfer. Fr multiple effect evaporation linkedin slideshare. For a multiple effect evaporator system calculations, the. It is the operation which is used for concentration of solution. The vapor from the first effect m v1 becomes the heating source for the second effect m s2.
Vacuum condensate product out feed steam steam figure 4 apv evaporator hndbook 12600 11. Evaporation is an unit operation by which a solvent is evaporated from a solution by boiling the liquor in a suitable vessel and withdrawing the vapor, leaving a concentrated liquid residue. However, using the falling film technique, it is feasible to have as many as 10 or more effects. Online calculations for multiple effect evaporators for the sugar industry. Abstract the main goal behind this project is to treat highly generated tds, tss, bod, etc. Mist flow conditions should be avoided because poor heat. The product is heated through its recirculation in the heat exchanger to then be partially evaporated when the pressure in the flash.
Thermodynamic design of condensers and evaporators. May 21, 2016 evaporation is an unit operation by which a solvent is evaporated from a solution by boiling the liquor in a suitable vessel and withdrawing the vapor, leaving a concentrated liquid residue. Sep 29, 20 this book deals with the modeling and simulation of multiple effect evaporators. Pdf a simplified and generalized method to size multipleeffect. Economy calculations are determined using enthalpy balances. The thermodynamic design of multiple effect forcedcirculation evaporator systems. Development of a new model for multiple effect evaporator system. Design calculations for multipleeffect evaporators. Design of multiple effect forcedcirculation evaporators. Pdf desain multi effect evaporator dengan menggunakan. Design of multiple effect evaporators has received considerable attention over the last 30 years and several key contributions have appeared in the literature. Optimum surface area distribution of multipleeffect evaporator for. 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.
Design, modelling and simulation of multiple effect evaporators. A multiple effect evaporator is an evaporation systems where the vapour extracted from one effect is used as heating medium for the next effect at a lower pressure. In doing calculations for a triple effect evaporator system, the values to be obtained are usually the area of the heating surface in each effect, the kg of steam per hour to. Jan 15, 2017 multiple effect evaporator problem guided by prof. The solution procedure draws heavily from the degree of. Shabina khanam may2012 department of chemical engineering national institute of technology rourkela, orissa. Koko, 1987 for the design of multipleeffect evaporator systems with backward feed is simplified and. Because the boiling temperature of water decreases as pressure decreases, the vapor boiled off in one vessel can be used to heat the. The vapor, however, is solute free, so it wont condense until the extra heat. In a double effect evaporator, the vapor product off the first effect is used to provide energy for a second vaporization unit.
Feed 3000 kghr, feed temperature 30 degc, intial tds 5%, final tds 30%, available steam pressure for tvr 6. Single effect evaporation desalination processthe feed seawater mf is chemically treated and deaerated before beingpumped to the evaporator. For optimum cost the maximum number of effects in a multiple effect evaporator usually. These metrics are regularly updated to reflect usage leading up to the last few days. In an evaporator handling an aqueous salt solution, the overall coef. Two or more effects operate at progressively lower vacuums and thus with progressively lower boiling points. This type of multiple effect system is perfect for continuous feed applications, as fluids are progressively reduced in each effect to final concentration discharge. The multiple effect configuration combines two or more evaporator bodies to conserve steam, which is condensed in the first effect heat exchanger only. The chemical treatment is needed to prevent thefoaming and the tendency for scale formation in the evaporator. In case of multiple effect evaporation plants, the exhaust vapors from the product are used to heat the downstreamarranged evaporation effect so. For example, if steam is available at 220f 104c, then the last effect boiling temperature is 120f 49c.
The latent heat of the vapor leaving in single effect evaporator is not used but is discarded. To reduce the amount of steam needed, the evaporator is normally designed as a multiple effect evaporator. Multiple effect 3 evaporator steam consumption calculation posted in process heat transfer. The sugar juice evaporation process consists of juice heater, multipleeffect. Vapour flows and heat transfer areas are calculated. Teaching multiple effect evaporation in the junior year of the chemical engineering curriculum reinforces and integrates k ey topics from the sophomore year such as mass and energy balances, structured problem solving, and stea m table calculations. Figure 6 risingfalling film plate evaporator design apv 2008. Jun 03, 20 discussing and analyzing the performance of single effect evaporation process. There could be single effect evaporator or multiple effect evaporators. Optimization of a multiple effect evaporator system. This system is used in a singleeffect evaporator or in the first stage of a multipleeffect evaporator. Multiple effect evaporator, evaporator selection, design 1.
Desai page 12 this brings a saving in the steam cost, but at the same time, the cost of material and installation of the evaporator system increases because of the large number of effects involved. However, the solution is implicit for t s, thus requiring an iterative calculation procedure. Evaporation is the removal of solvent as vapor from a. Two different methods are used for calculating number of effects. The model includes overall as well as component mass balance equations, energy. Triple effect evaporator bpeirson structural 25 oct 03 15. Water evaporated in the first effect vapor body is condensed in the second effect heat exchanger, which provides energy for evaporation in the second effect vapor body and so on for additional.
Citations are the number of other articles citing this article, calculated by crossref and updated daily. Optimization of a multiple effect evaporator system ethesis. When the solution being evaporated has a significant boilingpoint rise, the capacity obtained is very much reduced, for the boilingpoint rise reduces the. Sep 16, 2016 the single effect evaporator uses rather more than 1 kg of steam to evaporate 1 kg of water. Multiple effect 3 evaporator steam consumption calculation.
Ii design of multiple effect forcedcirculation evaporators and crystallization systems u. With addition of each effect steam economy of the system also increases. Jul 05, 2019 abstract the main goal behind this project is to treat highly generated tds, tss, bod, etc. Multiple effect evaporators maximize steam economy as vapor generated from one effect is used to drive another. Evaporator operation in evaporation, solids may come out of solution and form a deposit or scale on the heat transfer surfaces. Multiple effect evaporator is the combination of several sets single effect evaporator. Lecture 7 evaporation presented by muhammad abbas ahmad zaini. For a multiple effect evaporator system calculations, the values required to be obtained are i the area of the heating surface in each effect, ii the kg of steam per hour to be supplied, and. Modelling and optimising single and multiple effect evaporators by. Sep 04, 2015 overview of a multiple effect evaporators.
In such a system, the heat from the original steam fed into the system is reused in the successive effects. In a multiple effect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. Noniterative design of multiple effect evaporators using. Pdf a simplified and generalized method to size multiple. 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 requirements for the degree of master of science in mechanical engineering thermal sciences by benjamin marc day, p. This system is used in a single effect evaporator or in the first stage of a multiple effect evaporator. The use of this system requires that steam be available at high pressure, and low. The utility model discloses a multiple effect evaporation waste water treatment system which comprises at least seven effect evaporators in series connection, wherein an air outlet of each effect evaporator is connected with a separator, an air outlet of each effect separator is connected with a heat. Construction of multiple effects, in handbook of cane sugar engineering.
Evaporation is the removal of solvent as vapor from a solution. While the design criteria for evaporators are the same regardless of the industry involved, two questions always exist. Pdf an iterative procedure previously presented in the literature lambert et al. The design calculations required for a multipleeffect evaporator are complex enough to provide a real challenge for implementation using a spreadsheet. Desai page the energy consumption to evaporate an aqueous solution is fairly significant. Calculation for multiple effect evaporator free download as word doc. Design of triple effect evaporator developed by a program. Evaporator is one of the most energy intensive sections of a number of process industries such as pulp and paper, sugar, desalination, pharmaceuticals, dairy and food processing, etc.
Scribd is the worlds largest social reading and publishing site. Take standard vertical short tube evaporator calendria type data. The multipleeffect evaporator was invented by the africanamerican engineer norbert. Multipleeffect evaporator design the design calculations required. A septuple effect flat falling film evaporator system for the concentration of black liquor is studied and a.
Noniterative design of multiple effect evaporators. A thesis on design of heat integrated multiple effect evaporator system submitted by ghoshna jyoti 210ch1201 for the partial fulfillment of master of technology under esteemed guidance of dr. As result of calculations, it has been found that about 3. Hi friends, i would like to calculate the multilple 3 effect evaporator steam consumption. The significant advantage of this arrangement is that it allows the original heat input to the system to be reused in each effect.
The case study is presented that multiple effect evaporator is has good overall steam economy instead of single evaporator. A multiple effect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water. The invention of the multiple effect evaporator is generally credited to norbert rillieux. Lecture 7 evaporation universiti teknologi malaysia. Jun 14, 2009 noniterative design of multiple effect evaporators using excel add ins. This is useful for low quantities or for the functioning of the multiple effect because there is no product waste at the end of the production cycle. Brine zero liquid discharge zld fundamentals and design. Multiple effect each individual effect will have a smaller temperature difference, thus high area of heating surfaces capital cost more costly operating cost steam economy, only required for the first effect 1 kg steam vaporizes 3 kg water small capacity but wasteful energy 1 kg steam vaporize 1 kg water. In this scenario a rising film evaporator would be limited to four. Heat transfer area is nearly equal for each effect. Brine zero liquid discharge zld fundamentals and design h 2 o salt h 2 o h h 2 o h 2 o salt salt h salt h 2 o h 2 o h salt salt salt salt salt salt salt h 2 o h 2 o h 2 o h 2 o h 2 o h 2 o % n a guide to the basic conceptualization of the zldmld process design and the relative technologies involved m salt.
Figure 1 shows a simplified scheme of a multi pleeffect evaporator with the principal variables of the process. A multiple effect evaporator is design to cut down the steam consumption by different operating strategies like feed, condensate and product flashing, vapor compression, vapor bleeding, feed and steam splitting and using an optimal feed flow sequence. A multipleeffect evaporator is an apparatus for efficiently using the heat from steam to evaporate water. Usually there is double effect evaporator, three effect evaporator or. In a typical multiple effect evaporator homework problem figure 1 the feed condit ions and flow rate f are given. The overall heat transfer coefficients u i are assumed to be known. As a result, many types of evaporators and many variations in processing techniques have been. Pdf detailed design of a single effect evaporator with.
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