In a singleeffect evaporator, steam provides energy for vaporization and the vapor product is condensed and removed from the system. A feed containing 2 wt% dissolved organic solids in water is fed to a double effect evaporator with reverse feed at a rate of lbshour. The single effect evaporator uses rather more than 1 kg of steam to evaporate 1 kg of water. Dynamic response of a double effect evaporator andre. 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 be supplied, and the amount of vapour leaving each effect, especially in first effect. First, one considers a linearizing control, then a pi control is designed. Pdf a simplified and generalized method to size multipleeffect. Adding a thermocompressor to a threeeffect system can approximately double the economy, but that pales in comparison to the potential steam economy of an evaporator with mvr which is 510 times that of the threeeffect evaporator. Evaporators are classified by the number of effects. However, energy consumption per unit production can be reduced. Dynamic response of a double effect evaporator wiley online library. The solution to be processed and the heating steam are fed in the parallel scheme. Scribd is the worlds largest social reading and publishing site. Pdf single and multiple effect evaporators pranavv.
This is useful for low quantities or for the functioning of the multipleeffect because there is no product waste at the end of the production cycle. A multipleeffect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water. This type of multipleeffect system is perfect for continuous feed applications, as fluids are progressively reduced in each effect to final concentration discharge. A wide variety of double effect evaporator options are available to you, such as power source, application, and process. Optimum design and operating conditions of multiple effect evaporators. In a doubleeffect evaporator, the vapor product off the first effect is used to provide energy for a second vaporization unit. Its divided in to three category on the basis of feed direction. Usually there is double effect evaporator, three effect evaporator or. Multiple effect evaporator evaporation boiling free. Multipleeffect evaporators maximize steam economy as vapor generated from one effect is used to drive another.
The following illustration shows an indirect condenser. Because the boiling temperature of water decreases as pressure decreases, the vapor boiled off in one vessel can be used to heat the. Multipleeffect vacuum evaporators condorchem envitech. Boiling point rise and heat of solution are both negligible. Improving the efficiency of multiple effect evaporator to treat effluent from a pharmaceutical industry article pdf available january 2014 with 4,226 reads how we measure reads. The mass flow rate and temperature of the feed entering the first system are kghr and 20 c respectively. Usually it is possible to solve the material and energy balances analytically by a sequential approach. Optimization of a multiple effect evaporator system. Single effect evaporator calculations are fairly basic. Control strategy for multiple effect evaporator process. Page 1 of 2 control strategy for multiple effect evaporator posted in process heat transfer. Multiple effect evaporator mass and enthalpy balance.
Optimization of multiple effect evaporators designed for fruit juice. For the same evaporation rate, a fiveeffect evaporator will require about 25% of the steam required for a singleeffect evaporator. Design of triple effect evaporator developed by a program. Abstract the main goal behind this project is to treat highly generated tds, tss, bod, etc.
Outlining features of various evaporator configurations2. For the love of physics walter lewin may 16, 2011 duration. The open loop dynamic response of a laboratory scale double effect evaporator has been adequately described by a simple mathematical model based on the unsteady state material and energy balances associated with the various elements of the system. For the sake of simplicity, the fluid under study is pure water conventional use of. Principles of food and bioprocess engineering fs 231. An application of nonlinear feedback theory to the control of a double effect evaporator is presented. In actual practice, the steam economy can vary widely because of. Evaporation of water is nearly doubled in double effect evaporation system compared to single effect per unit mass of steam used. The latent heat of the vapor leaving in single effect evaporator is not used but is discarded 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 heating medium for the. Take standard vertical short tube evaporator calendria type data. The case study is presented that multiple effect evaporator is has good overall steam economy instead of single evaporator. Schematic of tripleeffect backward feed evaporator with vapor bleeding 50 showing the different variables fig. Introduction the aim of this unit is to study the operation at steady state of a double effect evaporator, under reduced pressure. Modeling of the evaporator and model order reduction are briefly considered.
In this scenario a rising film evaporator would be limited. In a multiple effect evaporator the vapour from one evaporator is fed into the steam chest of the other evaporator. A single and multiple effect evaporators are well documented. Usually, the operating pressure or temperature of the vapor condenser is known, and can be used to determine the temperature using. In this mechanical design a short tube vertical evaporator stv, calandria type has. The main physical phenomenon encountered in this system is the heat transfer during distillation and concentration process. A multipleeffect evaporator is an apparatus for efficiently using the heat from steam to evaporate water. In an evaporator handling an aqueous salt solution, the overall coef. Heat transfer area is nearly equal for each effect. Typically, the operating temperature is not provided. Consider two evaporators connected so that the vapour line from one is connected to the steam chest of the other as shown in fig.
Discussing and analyzing the performance of single effect evaporation process. The utility model discloses a multipleeffect 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. Double effect evaporator free download as word doc. The use of this system requires that steam be available at high pressure, and lowpressure steam is required for the evaporation process. The evaporation in each effect will be approximately 0. Multiple effect evaporator is the combination of several sets single effect evaporator. Improving the efficiency of multiple effect evaporator to. This paper deals with the modeling of a chemical engineering system, which is the double effect evaporator dee.
Seawater enters the first effect at 300k at a rate of 5000 kgh, and saturated steam at 4. In a multipleeffect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. Multiple effect evaporator, feed arrangements, optimum no. 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. Simulation and control of a commercial double effect. The unit also allows the steam generated in the first evaporator to be introduced as heating medium in the second evaporator and the concentrated product obtained can be used as supply for the second column. Evaporation is the removal of solvent as vapor from a. This is known as multiple effect evaporators because each time the vapor is used, it acts as a single effect evaporator. Design and simulation of a multipleeffect evaporator.
Pdf 22 multiple effect evaporator system maryam alhosni. Schematic of the fiveeffect backward flow evaporator with vapor 39 bleeding fig 5. Solved a doubleeffect evaporator two evaporators in. Density of liquid 10 wt% glycerol 1019 kgm3 density of water vapour pmrt. What are typical control strategies employed for a multiple effect evaporator. Specifically, double effect chillers can produce water of much lower temperature and have greater thermal cops. I tried liptaks handbook but they mostly focus on single effect issues. Steam economy increases steadily in multipleeffect evaporators as the number of effects increases. Pdf design of heat integrated multiple effect evaporator. A doubleeffect evaporator two evaporators in series is used to produce fresh water from seawater containing 3. Pdf optimization of multiple effect evaporators designed for fruit. Direct or indirect condensers based on the size of the evaporator. Seawater enters the first effect at 300 k at a rate of 5000kgh, and saturated steam at 4. Thus, one of the main premises of a double effect ev aporator, which is the economy of the heat employed, can be evaluated.
Given that evaporation is a separation system, the presence of three different fluids is found. Pdf optimum design and operating conditions of multiple. The nonlinear controller is designed in a twostage procedure. The mass flow rate of the vapor leaving the second system is 150 kghr. Multiple effect evaporators, optimum number of effects. As result of calculations, it has been found that about 3. Pdf the most important running cost item in evaporation is energy. The overall heat transfer coefficient in the first and second system are 1,500 wm2 k. Schematic of the threeeffect evaporator with specified variables 48 fig. The multipleeffect evaporator was invented by the africanamerican engineer norbert. The modeling of dee is carried out using bond graph approach.