Evaporation is a way to make a liquid, usually water, more concentrated by turning it into vapor. Unlike distillation, it doesn't separate the vapor into different parts.

Although, they have different types, pros, cons, and uses, which we'll talk about in this blog.

How Does It Work?

Industries use evaporators to concentrate products by evaporating water. These evaporators can range from single effects to seven effects, depending on how much product needs processing.

The technology is based on a simple principle: reducing the quantity by concentrating the product and then separating the wate

r. First, the product effluent is fed into the evaporator to increase its solids concentration, typically from 30% to 90%. The process operates under vacuum conditions. Finally, the system recycles the vapors produced to conserve steam, especially in multiple-effect evaporation systems, using a thermal vapor recompression system.

In this system, steam compresses the vapors generated in the evaporator. These compressed vapors then function as

 a heating medium in the evaporator. Reusing the vapors reduces steam consumption, making evaporators more economical than traditional methods.

TYPES

• Falling Film Evaporators
• Force Circulation Evaporators
• Batch Evaporators

• Wiped Film Evaporators
• Scraped Surface Evaporator
• Thin Film Evaporators

Falling Film Evaporators

The long-tube falling-film evaporator is a modified version of the long-tube rising-film evaporator. In this setup, the equipment is inverted so that the tubular heat exchanger rests at the top of the liquid separator area.

The feed enters from the top, where distributors evenly distribute it into each tube. Proper feed distribution is crucial, and various distributor designs are available, usually involving a perforated plate placed on top of the tube sheet.

Because of gravity, the film moves downwards, which is an advantage of the falling-film evaporator. This ty

pe of evaporator is commonly used when the temperature difference between the heating medium and the

 liquid is small.

Application

Many industries commonly employ this method in food processing, pharmaceuticals, and chemical indust

ries to efficiently remove water or solvents from solutions. Also, it is preferred for its gentle treatment of heat

-sensitive materials and its effective handling of low-temperature applications.

Force Circulation Evaporators

Forced circulation evaporators are employed to avoid excessive boiling of the liquid on the heating s

urfaces, as it may cause salt accumulation and fouling. So, in these evaporators, we make sure the liquid flows through the tubes fast.

The liquid flows rapidly through the tubes, with steam being introduced into the chamber. Although the 

pressure decreases, some of the liquid evaporates, and a specialized pump aids in circulating the liquid

 through the evaporator. Additionally, this type of evaporator works well for liquids that are thick or tend to form crystals during evaporation.

Application

Forced circulation is used in various applications such as producing urea, sodium sulfate, sodium chloride, magnesium chloride, caustic potash, citric acid, and ammonium sulfate.

Batch Evaporators     

Batch evaporators work by filling them with a liquid that needs to be concentrated. Heat is then applied, slowly concentrating the liquid by removing vapors. As the concentration happens, more liquid might be added to maintain a certain level. Because each added liquid brings some solids with it, the evaporator eventually reaches the desired concentration level.

Application 

Industries utilize batch evaporators to concentrate liquids in batches for various purposes, including food processing, pharmaceutical manufacturing, chemical production, environmental applications, cosmetics production, and the petrochemical industry. 

Wiped Film Evaporators

Wiped Film Evaporators (WFE) are used in difficult evaporation processes where heat sensitivity, thicknes

s, surface fouling, or high temperatures are issues. They are used all over the world and can be arranged in different ways. Moreover, some feature internal condensers and are termed short path evaporators, capable of operating under high vacuum conditions. The other type, without internal condensers, goes by the name top vapor outlet (TVO) evaporators and serves as column reboilers or in particularly dirty situations.

Application

Various industries utilize wiped film evaporators for diverse applications. In the pharmaceutical sector, food and beverage industry,  chemical field, and oils industry, they aid in the extraction and concentration of essential oils. Moreover, wiped film evaporators play a crucial role in environmental applications by helpi

ng purify contaminated liquids and wastewater.

Scraped Surface Evaporators

Typically, industries choose this type of evaporator for thick or sticky products prone to forming scales or salt deposits during evaporation. The rotating blades inside the evaporator make sure no material stays on the heating surface for too long, preventing it from getting too hot and degrading.

The liquid can flow from the bottom to the top or from the top to the bottom, depending on the pro

perties of the fluid and the likelihood of scale or crystal formation. This system can also serve as the

 final stage, working in conjunction with falling film or forced circulation evaporators.

Application

Scraped surface evaporators are like multitasking machines used in many industries. In the food industry, helps to make juices, dairy products, and sauces thicker. Also, they work wonders in pharmaceuticals to make medicines and herbal extracts stronger. In the chemical world, industries utilize them for producing resins and plastics, while in cosmetics, they employ them to thicken creams and lotions. Furthermore, they even help out in petrochemicals for making waxes and oils, and in cleaning up environmental messes by concentrating waste.

Thin Film Evaporators

Agitated thin-film evaporators are great for dealing with tricky materials. Following, tubular evaporators don't handle heat-sensitive, fouling, viscous, and high-boiling liquids well. 

Common issues with tubular evaporators include degradation from long residence times, fouling of heat transfer surfaces, tube blockages, poor heat transfer, and high-pressure drops.

Agitated thin-film evaporators solve these problems for hard-to-handle materials. This method quickly separates volatile and less-volatile substances using indirect heat transfer and mechanical agitation of product films.

Application

Industries widely use this method to purify organic chemicals such as natural oils, fatty acids, herbicides, and insecticides. It's also handy for concentrating foods and pharmaceuticals, such as vegetable and fruit purees, plant and vegetable extracts, and biological solutions. Additionally, it helps reduce harmful waste disposal, making it environmentally friendly.

Conclusion

Evaporators are essential in various industries for concentrating liquids by converting them into vapor. They find applications in pharmaceuticals, food processing, chemicals, and environmental remediation. One of the best evaporators made in the USA, they efficiently process liquids, contributing to product quality and environmental sustainability.