Types of Evaporator

in this ppt i descussed about evaporator.evaporation,Evaporation is the process by which an element or compound transitions from its liquid state to its gaseous state below the temperature at which it boils.
types of Evaporators
Open kettle or pan
Horizontal tube natural circulation evaporator
Vertical tube natural circulation evaporator
Long tube vertical evaporator
Falling film evaporator
Forced circulation evaporator
Open-pan solar evaporator

1. Communication skills-iii Evaporator Submitted by:- Sumit Patel 20BPE137D SoET Submitted to:- Mr.Arvind Kumar PDEU

2. Introduction evaporation, the process by which an element or compound transitions from its liquid state to its gaseous state below the temperature at which it boils. Example of evaporation Drying of clothes in the sun: The water present in the clothes when they are washed is removed by the process of evaporation. Evaporation of acetone which is used for removing nail paint 

3. Types of evaporator Open kettle or pan Horizontal tube natural circulation evaporator Vertical tube natural circulation evaporator Long tube vertical evaporator Falling film evaporator Forced circulation evaporator Open-pan solar evaporator

4. Open kettle or pan Principle The steam jacketed kettle or evaporating pan is an evaporator that can be used for the bulk evaporation of water from aqueous liquids. Working Steam is supplied through the inlet. Steam gives out its heat to the contents and the condensate leaves through the outlet. The rate of evaporation is fast in the initial stages and decreases gradually as the liquid gets concentrated.

5. Applications Concentrating aqueous liquids Concentrating thermo stable liquors (ex. Liquorice extracts) Advantage Evaporating pan is constructed both for small-scale and large-scale operations. It is simple in construction and easy to operate, clean, and maintains. Its cost of installation and maintenance is low. A wide variety of materials can be used for construction such as copper, stainless steel, and aluminum. Stirring of the contents and removal of the product is easy .

6. Disadvantages In evaporating pans, the heat economy is less. Hence. cost per unit material production is more. It is not suitable for heat-sensitive materials due to a long time of exposure. The heating area decreases as the product gets more concentrated. As it is an open type, the vapor passes into the atmosphere, which can lead to saturation of the atmosphere, slowing evaporation as well as causing discomfort. The boiling point of water cannot be reduced, since reduced pressure can not be created in an open type of evaporator.

7. Horizontal tube natural circulation evaporator Principle Steam is passed through the horizontal tubes, which are immersed in a pool of liquid to be evaporated. Heat transfers through the tubes and the solvent evaporates. Concentrated liquid is collected. Working Feed is introduced into the evaporator until the steam compartment is immersed. The horizontal tubes receives the heat and conduct it to the liquid. The feed absorbes heat and solvent gets evaporated. Concentrated liquid is collected.

8. advantage its relatively low cost per unit of heat surface. its extreme simplicity easy renewal of the heating surface its ability to carry a large volume of liquor in the body when finishing to a definite density. disadvantage it may be used only when rigorous boiling can be obtained with natural circulation. its use should be avoided when scailing or salting liquids are involved. application horizontal-tube evaporators are widely used in the evaporator of sugar syrups, Twitchell sweet water, tank water, beef extract, phosphoric acid, zinc chloride.

9. Vertical tube natural circulation evaporator principle Liquid is passed through the vertical tubes and steam is supplied from outside tubes. Heat transfer takes place through the tubes and the liquids inside tube gets heated. The solvent evaporates, vapor escapes from the top and concentrated liquid is collected from bottom. working Steam is presented outside the tubes. The condensate is gone through the comparing out let and non dense gasses escape through the vent.

10. The bolster is presented so as to keep up the fluids level somewhat over the highest point of the tubes. The fluids in side the tubes is warmed by the steam and starts to bubbles. As the fluid bubbles it gushes up through the tubes and returns through the focal down take. It set up a dissemination of hot fluid which upgrades the rate of warmth exchange. The vapor escapes through the top outlets. Steam is provided until required grouping of the items is acquired. At long last the items can be pulled back from the scrape the bottom let. Application Vertical tube evaporator or short tube evaporator is utilized as a part of the produce of the cascara remove, salts and scathing pop, and make of salts.

11. Advantage Increases the heating surface 10-15 times than steam jacketed kettle. Fiery flow improves the rate of warmth exchange. Various units can be joined to got more proficient impact. Disadvantage Liquid to be maintained above calandria. Complicated- increased installation cost. Pressure has to maintain. Cleaning and maintenance is difficult. 

12. Long tube vertical evaporator working In this evaporator, feed enters the bottom of the tubes, gets heated by the condensing steam, starts to boil part way up the tubes and a mixture of vapour and liquid issues from the top of tubes and finally impinges at a high velocity on a deflector. The deflector acts both as a primary separator and a foam breaker. Some part of the separated liquid is removed as a product and the remaining part is returned to the bottom of the evaporator.  application This type of evaporator is widely used for handling of foamy, frothy liquors.  It is used for the production of condensed milk and concentrating a black liquor in the pulp and paper industry.

13. advantage low cost large heating surface in one body low holdup small floor surface good heat transfer coefficients at all temperature differences disadvantage high head room generally unsuitable for salting and severely scaling liquids poor heat transfer coefficients of rising film at low temperature differences

14. Falling film evaporator working Feed enters from the top and flows down the walls of the tube. The liquid becomes vapor and forms small bubbles. They tend to fuse to form layers of bubbles. Concentration takes place during downward journey. Vapor and liquid are separated at the bottom. application Falling film evaporators are used extensively in chemical process industry, food and paper industry, dairy industry, Pharmaceuticals

15. advantage Suitable for high viscous liquids Liquid hold up time is less Liquid is not overheated Highly acidic and corrosive feeds can be concentrated  disadvantage Not for suspensions, salting and scaling liquids Poor feed distribution in tubes Feed ratio is high

16. Forced circulation evaporator Working Feed is introduced through the liquor inlet. Pump will force the liquid through the calandria. Steam heats the liquid inside the calandria. As it is under pressure in the tubes the boiling point is elevated and no boiling takes place. As the liquor leaves the tubes and enters the body of the evaporator through the tangential inlet there is a drop in pressure and vapor flashes off from the superheated liquor. The concentrated liquid is pumped out through the product outlet and the vapor is collected through the vapor outlet.

17. Application These evaporators are mainly used for thermolabile materials. These can also be used in practice for the concentration of insulin and liver extracts. Advantage In force circulation evaporator there is a rapid liquid movement due to high heat transfer coefficient. Salting, scaling and fouling are not possible due to force circulation. This evaporator is suitable for themolabile substance because of rapid evaporation. It is suitable for the viscous preparation because pumping mechanism is used.  Disadvantage The equipment is expensive because the power is required for the circulating the liquids. The hold up of liquids is high.

18. Open-pan solar evaporator Solar energy is used to evaporate the water from the solution Application Solar evaporators are used in contaminated water purification, sea water desalination, electric generation, steam sterilization, and fuel production. Advantage No more energy used cheap Disadvantage Low scale evaporator Takes longer time

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