Unesco eolss sample chapters thermal desalination processes vol. Dynamic simulation of multiple effect evaporators in paper industry using matlab deepak kumar, anjana rani gupta, somesh kumar udepartment of mathematics, niet greater noida, up. A high temperature heating medium generally is necessary to obtain a reasonable evaporation rate since the heat transfer surface available is relatively small as a direct. Evaporators are the largest heat users and major contributors to losses in sugar cane factories. In a singleeffect evaporator, steam provides energy for vaporization and the vapor product is condensed and removed from the system. Solution of multiple effect evaporator problems sciencedirect. Evaporator selection considered in detail in volume 6, has been discussed by moore and hesler20 and parker21. Gams and solved simultaneously using a twostep solution strategy. Sep 04, 2015 mass and enthalpy balance of a triple effect evaporator.
A singleeffect evaporator is used and the overall heattransfer coefficient is 1500 wm 2. Multiple effect evaporator mass and enthalpy balance youtube. Problem statement the problem can be stated as follows. Single effect evaporator evaporation is to be used. In the first step of the strategy, the nlp model of mees is solved, providing an initialisation point for solving the minlp model of the combined mees. Multiple effect evaporators if the water vapor from the first effect of a multiple effect 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. Design of triple effect evaporator developed by a program. For example, if steam is available at 220f 104c, then the last effect boiling temperature is 120f 49c. Mass and enthalpy balance of a triple effect evaporator.
Their research was later extended in order to investigate the liquid flowpatterns of a multiple effect evaporator. Mathematical model for a multiple effect evaporator system. A multiple effect evaporator is an evaporator system in which the vapor from one effect is used as the heating medium for a subsequent effect boiling at a lower pressure. Density of liquid 10 wt% glycerol 1019 kgm3 density of water vapour pmrt. Estimate the requirements of steam and heat transfer surface, and the evaporating temperatures in each effect, for a triple effect evaporator evaporating 500 kghr of a 10% solution up to a 30% solution. No vacuum in a multiple effect evaporator industrial. In the operation of the multipleeffect evaporators there is a number of aspects which incide. The multiple effect configuration combines two or more evaporator bodies to conserve steam, which is condensed in the first effect heat exchanger only. Fortunately, the overall approach is basically the same for the majority of problems, requiring only minor adjustments to.
These are forward feed multi effect evaporator, backward feed multi effect evaporator, mixed feed multi effect evaporator and parallel feed multiple effect evaporator. Design and simulation of a multiple effect evaporator using vapor bleeding. Detailed design of a single effect evaporator with thermal vapor re compression thesis pdf available march 2016 with 4,990 reads how we measure reads. All these problems may be overcome when the liquid is circulated at high velocity. Dear colleagues,i am now working on a 3 effect evaporator in my plant. For a multiple effect evaporator system calculations, the values required to be obtained are. Selection from transport processes and separation process principles includes unit operations fourth edition book.
Steam is available at 320f, and the vapor from the last stage is condensed at 120f. Feed at 20 c containing 10 % solids enters an evaporator operating at 85 c. In this study, investigation of selection of type of evaporator using some parameters is presented for multiple effect evaporator system. Pdf a simplified and generalized method to size multipleeffect. Block diagram of a single effect in a multipleeffect evaporator 31 fig. This is to certify that the project entitled design and simulation of a multiple effect evaporator using vapor bleeding is an original work done by monalishanayak, roll no.
At first sight, it may seem that the multiple effect evaporator has all the advantages, the heat. This method of evaporation in series is called multiple effect evaporation, and each stage is called an effect. The main steps are given, but the students will have to fill in the blank points. In a multipleeffect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. A multipleeffect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water. These factors make effective evaporator control crucial to. Vapor flashing free evaporation occurs when feed liquor is at high temperature or. A singleeffect submerged tube system, which is shown in figure 1, was the first and simplest method used to desalt seawater in large quantities.
Temperature, vapor flow rate, liquid flow rate, pressure bleeding, composition and other process variables. For this purpose, a septuple effect flat falling film evaporator sefffe system with backward feed flow sequence, being used for concentrating weak. Design and simulation of a multipleeffect evaporator. Multiple effect evaporator the multiple effect configuration combines two or more evaporator bodies to conserve steam, which is condensed in the first effect heat exchanger only. In this context, the present manuscript describes the successful implementation of a digital twin to represent a fourstage multi effect evaporation train from an industrial sugarcane processing. These metrics are regularly updated to reflect usage leading up to the last few days. For the multi effect system, each individual evaporator will have a smaller temperature drop, but the overall temperature drop will be the same for the 3 effect and for the single effect system. The heating medium normally is high pressure steam or oil. In a multiple effect evaporator the vapour from one evaporator is fed into the steam chest of the other evaporator. Simultaneous optimisation of multipleeffect evaporation. Using mass and energy balance around an effect, a cubic polynomial equation is developed to model an effect, which is solved using generalized cascade algorithm. Multiple effect 3 evaporator steam consumption calculation. Noniterative design of multiple effect evaporators using.
Optimization of a multiple effect evaporator system ethesis. Jul 21, 2008 no vacuum in a multiple effect evaporator posted in industrial professionals. Energy and economical equations are given with a case study for multiple effect evaporator system. The economy of a single effect evaporator is always less than 1.
Evaporation is to be used to concentrate 3000 kgh of a 10% solution of naoh in water entering at 70c to a product of 45% solids. Estimate the requirements of steam and heat transfer surface, and the evaporating temperatures in. Multiple effect evaporator example free download as pdf file. The latent heat of the vapor leaving in single effect evaporator is not used but is discarded. Dynamic simulation of multiple effect evaporators in paper. Values of different variables for three effect evaporator system 48 table. The most difficult part of a course in food engineering is often. The process inside and andritz evaporator relies on a free flow falling film of liquor over the surface of the lamella. However, pumps, interconnecting pipes and valves are required for transfer of liquid from one effect to another effect that increases both equipment and. With the semi solved problems the students are guided through the solution.
Feeding of multiple effect evaporator multiple effect evaporator divided in to four categories on the basis of feed direction as shown figure 25. The multiple effect evaporator mee is an energy intensive step in the kraft pulping process. Design, modelling and simulation of multiple effect. If more than one evaporator is used for the concentration of any solution, it is called a multiple effect evaporator system. Effect of evaporator pressure consider a simple saturation cycle 1234 with freon 12 as the refrigerant as shown in figure 2. Evaporation is the removal of solvent as vapor from a. Design and simulation of a multipleeffect evaporator using vapor bleeding. Because the boiling point of water decreases as pressure. Calculate a the power input to the compressor, in kw b the coefficient of performance. Its divided in to three category on the basis of feed direction. For this purpose an unsteadystate model for the multi effect evaporator system is developed. Multiple effect evaporator mass and enthalpy balance. For single effect evaporator, the steam economy is about 0. Scribd is the worlds largest social reading and publishing site.
Introduction in evaporation of solutions in a singleeffect evaporator, a major cost is the cost of the steam used to evaporate the water. Multiple effect evaporator control is a problem that has been widely reported in the pulp and sugar industries. In this method, the evaporator has one or two horizontal or vertical tube bundles representing the heating surface and contained in the lower part of a shell. Feed solution is at 60 degrees c with a specific heat capacity of 4. In a multiple effect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. The model is solved through a simple sequence of manual calculations. Take standard vertical short tube evaporator calendria type data.
Steam condensation inside horizontal tubes and seawater evaporation on the outer side is the heart of one of the most common med processes. Principles of food and bioprocess engineering fs 231 example problems on evaporation 1. A multiple effect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water. Evaporation of the solvent takes place as the thin film moves down the evaporator wall. Mathematical model for a multiple effect evaporator system with condensate. Refrigeration cycle is the basis of all refrigeration systems. Multiple effect evaporator mass and enthalpy balance duration. Hi friends, i would like to calculate the multilple 3 effect evaporator steam consumption. 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. Introduction in evaporation of solutions in a single effect evaporator, a major cost is the cost of the steam used to evaporate the water. Iterative results for the simple three effect system 47 table 5. Typically, multiple effect evaporator calculations require an iterative solution procedure because so many of the required properties, etc. Each effect, in itself, act as a single effect evaporator, and each has a temperature drop across its heating surface corresponding to the pressure drop in that effect.
Given that evaporation is a separation system, the presence of three different fluids is found. Nov 18, 2015 separation process evaporation example multiple evaporators tan hong li. The stripper is part of the multiple effect evaporator system. A multiple effect evaporator is an equipment system for efficiently using the heat from steam to evaporate water. Multiple effect evaporator example latent heat heat. Parker has attempted to test the suitability of each basic design for dealing with the problems encountered in practice, and the basic information is presented in the form shown in figure 14. Principles of food and bioprocess engineering fs 231. A triple effect evaporator is to be used to produce a 50 percent naoh solution from a feed containing 25 percent naoh. Article views are the countercompliant sum of full text article downloads since november 2008 both pdf and html across all institutions and individuals. A multipleeffect evaporator is an evaporator system in which the vapor from one effect is used as the heating medium for a. Q heat transfer in the first effect q heat transfer in the second effect q heat transfer in the third effect overall heat transfer coefficient since it is a vertical effect evaporator, the overall heat transfer coefficient can safely be assumed as follows. The thermal condition of the evaporator feed has an important impact on economy and performance. 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. This can be explained by noting that the state of the working fluid moves closer to the dead state as it is heated at a temperature below t o.
Double effect evaporator free download as word doc. No vacuum in a multiple effect evaporator posted in industrial professionals. The evaporator is mainly composed of 3 flash drums, 3 heat exchangers, and 1 final condenser. Energy and material balance for a five effect evaporator was performed in the multiple effect evaporators. Multiple effect evaporators have higher economy but lower capacity than single effect. In the present study dynamic behavior of multi effect evaporator system of a paper industry is obtained by disturbing the feed flow rate, feed concentration, live steam temperature and feed temperature. All textbooks 3,4,5 that cover evaporation present a pencilandpaper iterative approach. Sep 16, 2016 the single effect evaporator uses rather more than 1 kg of steam to evaporate 1 kg of water. Citations are the number of other articles citing this article, calculated by crossref and updated daily.
Design and simulation of a multipleeffect evaporator using. In the first effect u 1 2325 wmc in the second effect u. The computer solution to such problems can follow exactly the usual manual method. Pdf detailed design of a single effect evaporator with. Operating parameters for the fiveeffect evaporator 29 table 5.
Design calculations for multipleeffect evaporators. Possible methods to solve multiple effect problems several approaches can be used to solve the typical multiple effect evaporator homework problem. The apv forced circulation evaporator system is designed for the evaporation of liquids containing high concentrations of solids. In particular, the system is used as a finishing evaporator to concentrate materials to high solids following a low solids multi effect or mvr film evaporator. Characterization and effects of scale formation on heat. Schematic view of a horizontal tube multieffect distillation plant ide design, internet publication.
Design and simulation of a multiple effect evaporator. Configuration screen of multipleeffect evaporation visualbasic application. The typical feeding method of multi effect evaporators is forward feed. Pdf single and multiple effect evaporators pranavv. A simplified diagram of a forwardfeed triple effect evaporation system is. A tripleeffect evaporator is to be used to produce a 50 percent naoh solution from a feed containing 25 percent naoh. Multiple effect evaporator example latent heat heat transfer. 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. Desai page 1 study the steam economy of multiple effect evaporator plant producing sodium sulphate and its simulation a project report submitted by rohan a. Calculates the heat transfer area for a singleeffect evaporator that is used to concentrate a salt solution. Schematic view of industrial multi effect evaporation mccabe et al. Feed 3000 kghr, feed temperature 30 degc, intial tds 5%, final tds 30%, available steam pressure for tvr 6.
Simultaneous optimisation of multiple effect evaporation. Fortunately, the overall approach is basically the same for the majority of problems, requiring only minor adjustments to compensate for problem quirks. Modeling and dynamic simulation of mixed feed multieffect. Therefore, the multi effect system will cost more in capital costs, since you have to buy three evaporators, versus one for the single effect system. Multiple effect 3 evaporator steam consumption calculation posted in process heat transfer. Optimization of a multiple effect evaporator system. A tripleeffect evaporator is to be used to produce a. Block diagram of a single effect in a multiple effect evaporator 31 fig. This chapter focuses on the solution of multiple effect evaporator problems. National institute of technology, rourkela department of chemical engineering, national institute of technology, rourkela.
Both feed and steam are introduced in the first effect and the feed passed from effect to effect parallel to the vapor from the earlier effect. The exergetic analysis can be useful for locating irreversibilities in. In case of multipleeffect 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. The amount of steam consumption in multiple effect evaporators is already mentioned in lesson 4.
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