OPERATION EVAPORATION TOOLS INDUSTRIAL CHEMISTRY CLASS : XIII SEMESTER : 8

EVAPORATION Evaporation process is the process of change fluide the liquid into the steam. Evaporation tool called the evaporator • Evaporation is a thermal separation process, aims to separate solvent of solution resulting in a more concentrated solution. Examples of the process evaporation is concentrate solution sodium hydroxide, sodium chloride, glyserol, and adhesive • Evaporation produce more dense liquid, but still concentrated liquid form that can be pumped as a result of a major, although sometimes there is also a volatile liquid as a result of the primary, for example, during the recovery solvent.

Why do evaporation process? Products need to have a concentration of non-volatile high Quality and stability of the product can be improved with water to remove Reduce the volume fluide will reduce the cost and storage Eliminate water will reduce the cost of handling waste Condense solvent that can be used again Recycling fluide purified

Implementation evaporation in the industry, among others Organic and inorganic products Environmental products Food products Textile dye Pharmaceutical products Non food liquids Chemical and Petrochemicals Water treatments Agrochemical

Evaporation implementation of the food industry Food liquids Brewery products Dairy products Fish protein industry Fruits juice extracts Coffee industry

The division process evaporation Evaporation types of lamina This type involving the lamina of the surface moves through the summer, for the custody transfer of heat on at least Evaporation type high pressure This type involves heating a product high above the normal boiling point, adding to the pressure so that no boiling occurred in the evaporator body. This process is often called the principle of heating and lightning

The special-use of evaporation Product concentration Dryer feed pre-concentration Volume reduction Water/solvent recovery Crystallization

Types based on the transfer of heat evaporator Aircraft are heated with direct fire Aircraft with the media in a heating jacket Aircraft with a heated area through fluide heating pipe-pipe

Energetics Evaporation can be distinguished from some other drying methods in that the final product of evaporation is a concentrated liquid, not a solid. Heat is added to the solution and part of the solvent is converted into vapor. Heat is the main tool in evaporation, and the process occurs more readily at high temperature and low pressures.

Energetics Heat is needed to provide enough energy for the molecules of the solvent to leave the solution and move into the air surrounding the solution. The energy needed can be expressed as an excess thermodynamic potential of the water in the solution. The energy requirement of this process is very high because a phase transition must be caused; the water must go from a liquid to a vapor.

Energetics When designing evaporators, engineers must quantify the amount of steam needed for every mass unit of water removed when a concentration is given. An energy balance must be used based on an assumption that a negligible amount of heat is lost to the system’s surroundings.

The heat that needs to be supplied by the condensing steam will approximately equal the heat needed to heat and vaporize the water. Another consideration is the size of the heat exchanger which affects the heat transfer rate. Teknologi dan Rekayasa

How an evaporator works The solution containing the desired product is fed into the evaporator and passes a heat source. The applied heat converts the water in the solution into vapor. The vapor is removed from the rest of the solution and is condensed while the now concentrated solution is either fed into a second evaporator or is removed. The evaporator as a machine generally consists of four sections. The heating section contains the heating medium, which can vary. Steam is fed into this section.

The most common medium consists of parallel tubes but others have plates or coils. The concentrating and separating section removes the vapor being produced from the solution. The condenser condenses the separated vapor, then the vacuum or pump provides pressure to increase circulation. Teknologi dan Rekayasa

Types of evaporators used today Natural/forced circulation evaporator Falling film evaporator Rising film (Long Tube Vertical) evaporator Plate evaporator Flash evaporator

Natural circulation evaporator Natural circulation evaporators are based on the natural circulation of the product caused by the density differences that arise from heating. In an evaporator using tubing, after the water begins to boil, bubbles will rise and cause circulation, facilitating the separation of the liquid and the vapor at the top of the heating tubes.

Problems can arise if the tubes are not well-immersed in the solution. The amount of evaporation that takes place depends on the temperature difference between the steam and the solution. Problems can arise if the tubes are not well-immersed in the solution. If this occurs, the system will be dried out and circulation compromised. Teknologi dan Rekayasa

Forced circulation evaporator In order to avoid this, forced circulation can be used by inserting a pump to increase pressure and circulation. Forced circulation occurs when hydrostatic head prevents boiling at the heating surface.

A pump can also be used to avoid fouling that is caused by the boiling of liquid on the tubes; the pump suppresses bubble formation. Other problems are that the residing time is undefined and the consumption of steam is very high, but at high temperatures, good circulation is easily achieved. Teknologi dan Rekayasa

Forced circulation evaporator

Effect Evaporation Plant with a Forced Circulation Evaporator for waste water

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 applicable to highly viscous solutions so it is frequently used in the chemical, food, and fermentation industry. Teknologi dan Rekayasa

Falling film evaporator usage A falling film evaporator is an industrial device to concentrate solutions, especially with heat sensitive components. The evaporator is a special type of heat exchanger.

A falling film triple effect evaporator for caustic soda

Rising film evaporator In this type of evaporator, boiling takes place inside the tubes, due to heating made (usually by steam) outside the same. is therefore not desired; the creation of water vapor bubbles inside the tube creates an asscenzional flow enhancing the heat transfer coefficient. This type of evaporator is therefore quite efficient, the disadvantage being to be prone to quick scaling of the internal surface of the tubes.

Sizing this type of evaporator is usually a delicate task, since it requires a precise evaluation of the actual level of the process liquor inside the tubes. Recent applications tend to favor the falling film pattern rather than this one. Teknologi dan Rekayasa

Plate evaporator Plate evaporators have a relatively large surface area. During evaporation, steam flows through the channels formed by the free spaces between the plates. The steam alternately climbs and falls parallel to the concentrated liquid. The steam follows a co-current, counter-current path in relation to the liquid.

The concentrate and the vapor are both fed into the separation stage where the vapor is sent to a condenser. Plate evaporators are frequently applied in the dairy and fermentation industries since they have spatial flexibility. A negative point of this type of evaporator is that it is limited in its ability to treat viscous or solid-containing products. Teknologi dan Rekayasa

Multiple-effect evaporators Unlike single-stage evaporators, these evaporators can be made of up to seven evaporator stages or effects. The energy consumption for single-effect evaporators is very high and makes up most of the cost for an evaporation system. Putting together evaporators saves heat and thus requires less energy.

Adding another effect reduces it to 33% and so on. Adding one evaporator to the original decreases the energy consumption to 50% of the original amount. Adding another effect reduces it to 33% and so on. A heat saving % equation can be used to estimate how much one will save by adding a certain amount of effects. Teknologi dan Rekayasa

Flash evaporator Flash (or partial) evaporation is the partial vaporization that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest unit operations. If the throttling valve or device is located at the entry into a pressure vessel so that the flash evaporation occurs within the vessel, then the vessel is often referred to as a flash drum. The liquid is heated in a heat exchanger and flashed in a flash vessel to achieve desired concentration.

Vacuum Flash Evaporator dehydrating 150 gpm methyl ester after final wash step

Rotary evaporator A simple rotary evaporator system was invented by Lyman C. Craig. The most common form is the bench-top unit, though large scale (e.g., 20L-50L) versions are available and are used in pilot plants in commercial chemical operations.

Rotary evaporator

Vacuum Evaporator Cold sap is pre-heated in the heat exchanger and is piped to the vacuum chamber. The low pressure created by the vacuum allows steam to be liberated at a temperature less than the normal boiling point of sap.

The sap concentrate passes back through the heat exchanger to help raise the temperature of the incoming raw sap. The sap concentrate is then finished in a heated evaporator to obtain the characteristic maple flavor. Teknologi dan Rekayasa

Vacuum Evaporator