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Falling & Rising Film Evaporator

Separation Lab Of Institute Of Chemical Engineering & Technology , University Of The Punjab Lahore
by

Junaid Khan

on 20 October 2012

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Transcript of Falling & Rising Film Evaporator

(cc) image by anemoneprojectors on Flickr Fahad Ilyas PG-09-10E09 Arsalan Sarwar CE-09-10E01 PG-09-10E12 Atif Ilyas Junaid Khan CE-09-10E13 Group Members (A4) Objective To study the effect of steam on rate of evaporation,steam consumption,thermal efficiency of evaporator and preheater, overall heat transfer coefficient and steam economy in Climbing & falling film evaporator at atmospheric conditions. Precautionary Measures While using evaporators some of the precautionary measures should be taken....... There are hot surfaces so use gloves. Glass apparatus may break, use carefully. Avoid direct contact with steam which may cause burn on skin. Water on floor may cause slip, keep floor clean of spilled water. Do not use steam pressure higher than 30 psig. Close steam supply valve immediately
if condenser water supply is off. Procedure Open all the valves and check all the outlet of water.
Analyze the arrangements of all the pipes.
Put the thermometers in all the thermovalves for observing temperatures.
First set the pressure of the steam at 10psig from valve of steam.
Take four beakers and wait for steady state to occur i.e. sufficient amount of vapor condensate started coming out.
At steady state start stop watch and collect samples of steam condensate, vapor condensate, concentrated product & cooling water along with their temperatures for certain time and record in observation table.
Change the steam pressure(i.e. 15psig, 20psig..) to new operating valve and repeat the steps. Working Water is made to flow through the inlet tube placed in preheater.
The feed is then transfered to calandria where steam is also introduced.
The feed e.g. water when entering in calandria, rise up through the tubes and its temperature rises gradually.
Some fraction of water is converted into steam and the mixture of vapors and water falls down the calandria.
From bottom of calandria this mixture is made to passed through the separator where liquid vapor separation takes place.
The concentrated end product is obtained at the bottom of the separator.
The vapors from Steam Pressure
(psig) 10 Sampling Time
(sec) 20 Mass of Condensed
vapor (g) 52 Mass of Condensed
steam (g) Mass of Conc.
Product (g) Mass of Cooling
Water (g) Pre-Heater T1 (C) T2 (C) Evaporator Condenser/Cooler Vapor Condensate Conc. Product o o T3 (C) T4 (C) o o T5 (C) T6(C) o o T7 (C) o T8 (C) T9 (C) o o 81 302 3425 19 61 61 78 18 19 19 78 91 15 20 66 91 144 2283 28 77 77 78 22 31 18 78 91 20 20 101 125 19 1372 55 82 82 77 27 59 27 77 91.5 Observations Evaporator:
Tube Diameter = inch
Tube Length = inch
No Of Tubes =
Material Of Const.= 0.5 70.5 2 Cu Pre-Heater/Condenser:
Type =
Tube Diameter = inch
Tube Length = inch
Material Of Const.= Shell & Tube 0.5 75 Cu Condenser/Cooler:
Type =
Tube diameter = inch
Tube Length = inch
Material Of Const.= Shell & Tube 0.5 150 Cu It is a process that involves the removal of water from the Solution by boiling the liquor n a suitable vessel(evaporator). Evaporation Evaporation is a cooling process It is a dimensionless performance measure of a device that was thermal energy such as steam turbine, a boiler or a furnace. A measure of the length of time required for a given amount of a substance to evaporate with the sampling time. Definitions Evaporation Rate Thermal Efficiency Applications Chemical Process Industries Food Industries Paper Industries For the heat sensitive liquids
LMTD= Log mean temperature difference U= Heat Transfer co-efficient Q= Rate of Heat Transfered to Water = Heat gained by the vapors Sampling time A= Heat Transfer Area T = Temperature Of Steam T = Boiling Temperature T = Temperature at the inlet of evaporator s b 3 Applied Equations Preheater allows more heat and mass transfer due to its more surface area as compared to an ordinary heater. Feed Water is entered into the preheater around which hot vapors from the seperator patrols and preheat the feed water. Calandria Pressure Indicator Pre-Heater Shell & Tube Heat Exchanger Vapor Condensate Cooled Water Steam Trapper Feed Valve Condensed/Cooled Water Valve Steam Line Vapor-Liquid Separator Concentrated Product Feed Inlet Steam Condensate Purge Valve Thermo Valves Feed Line Water is made to flow through the
inlet tube placed in the pre-heater The feed is then transfered to calandria
where steam is also introduced. The feed e.g water entering in calandria, rise up through the tubes and its temperature rises gradually. Some fraction of water is converted into steam and the mixture of vapors and water falls down the calandria. From bottom of calandria this mixture is made to passed through the separator where vapor-liquid separation takes place The concentrated end product is obtained
at the bottom of the separator. The vapors from the separator goes to the pre-heater along shell side of pre-heater and gives its heat energy to the feed line and raise the temperature of liquid along tube side and vapors itself condensed partially. The partially condensed vapors pass through the exchanger where couter flow of water is made to condensed the vapors coming from pre-heater. Stop the steam to flow out. Table Of Contents Climbing and falling film evaporator
Definitions
Applications
Parts of Climbing and Falling Film Evaporator
Procedure
Working Through Labeled Diagram
Observations
Applied Equations
Table Of Observations
Calculations
Table of Results
Conclusions Climbing & Falling Film Evaporator This type of evaporator is generally made of long tubes (4–8 meters in length) which are surrounded by steam jackets. The uniform distribution of the solution is important when using this type of evaporator. The solution enters and gains velocity as it flows downward. This gain in velocity is attributed to the vapor being evolved against the heating medium, which flows downward as well. This evaporator is usually applied to highly viscous solutions so it is frequently used in the chemical, food, and fermentation industry.. Parts Of Climbing & Falling Film Evaporator Preheater allows more heat and mass transfer due to its more surface area as compared to an ordinary heater. Feed Water is entered into the preheater around which hot vapors from the seperator patrols and preheat the feed water. Pre-Heater Evaporator Water from the preheater is sent to evaporator where it is heated and converted into vapors with steam as a heating agent coming from the boiler. Separator The mixture from the evaporator is entered
into the separator where concentrated product
settles down and vapors being lighter resides
in the upper part of the separator . The vapors
from the separator enters the preheater for
preheating purposes Condenser Vapors from the preheater enters the condenser and gets condensed(partially). The mixture of liquid and vapors then meet the cool water and again gets condensed. The liquid is then discharged. Valves Valves are used to regulate the flow of liquid. Labelled Diagram Table Of Observations Calculations M.Arslan Junaid Atif Fahad
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