Reciprocating Scraped Surface Heat Exchangers – HRS Unicus Series
The patented HRS Unicus Series is a scraped surface heat exchanger for high fouling and viscous fluid applications. It has been specially designed and developed to offer a solution for those difficult heat transfer applications where very viscous fluids are used or fouling appears.
The design is based on a traditional shell and tube heat exchanger with scraping elements inside each tube. The reciprocating movement of the scrapers mixes the fluid whilst cleaning the heat exchange surface. This keeps heat transfer high and reduces downtime. In addition, the scraping movements introduces turbulence in the fluid increasing levels of heat transfer.
This design makes the Unicus Series the ideal heat exchanger for applications where fouling or low heat transfer is a limiting factor. The Unicus Series can be applied in industrial and hygienic applications.
The gentle movement of the scrapers allows the system to be used with delicate products, such as whole fruit or vegetable pieces, without destroying the integrity.
Continuous improvements have allowed HRS Heat Exchangers to apply the Unicus Series in a wide range of markets and applications. By increasing the stroke speed of the scraper bar we have been able to increase the heat transfer rates considerably. By adding new scraper types we have adapted to the difficulties that new products may present. The increased range of models available has made it possible to offer economic solutions for small to big duty applications. From food industry to environmental industry, from biomass to evaporation applications, the Unicus Series is a robust solution where other types of heat exchangers fail to deliver a good result.
CHARACTERISTICS OF THE UNICUS
The Unicus Series heat exchanger consists of three main parts:
- The shell and tube part: Inside each interior tube a scraper bar is fitted.
- The separation chamber: This space separates the shell and tube heat exchanger from the drive cylinder that moves the scraper bars.
- The cylinder: This part provides the energy that moves the scraper bars. The cylinder can be pneumatic (smaller models) or hydraulic (bigger models).
A key component of the Unicus Series is the seal that separates the inner tube volume from the separation chamber. The seal prevents leakage of the product to the exterior. Several types of seals have been developed depending on the application.
BETTER HEAT TRANSFER THROUGH SCRAPING
The scraping system consists of a stainless steel rod to which the scraping elements are fitted. Various types of scrapers have been developed for the different applications the Unicus Series can handle. Materials such as Teflon and Peek (polyaryletheretherketone) are used. 120° scrapers allow for working with big particulates. The 360° scrapers are ideal for viscous fluid without particulates. As the product changes we adapt the geometry of the scraper. Scraping means fouling free heat transfer surfaces. No loss of heat transfer due to fouling.
Another advantage of the scraping action is the introduction of extra turbulence in the product. This results in a better transport of the product to and from the heat exchange surface which enhances heat transfer rates significantly.
UNICUS: A SCALABLE SOLUTION
Like with any ordinary shell and tube heat exchanger scale up to bigger duties is as simple as increasing the shell diameter and fitting more interior tubes in the shell. Unicus Series models are available in versions containing just one tube, up to models with 80 tubes inside. This allows Unicus Series models to have heat transfer areas between 0.7 and 100 m². A standard range of models up to 10 m² is available for hygienic food applications and other industrial applications, while the larger of models are tailored to final use.
The HRS Unicus Series is suitable for heat transfer applications in a very wide range of industries and has multiple uses, including:
- Dairy: Cheese, yogurt, creams, desserts, whey concentrate, ice cream, condensed milk
- Fruits: Juice concentrate, fruit preparation, fruit puree, diced fruit
- Vegetables: Processed vegetables, tomato concentrate
- Convenience food: Eggs, mashed potatoes, ketchup, mayonnaise, baby food, dressings, spreads, fats, oils
- Protein: Viscera, meat slurry, mechanically deboned meat, meat stuffing, minced meat, pet food
- Confectionary: Chocolate, pie filling, creams, pastes, marmalade, syrups, gelatine, starch, butter, margarine
- Beverages: Coffee extract, juice freezing, juice concentrate, yeast-malt extracts
- Cosmetics: Lotion, cream, gel
- Environmental waste: Waste concentration: brine, manure, food plant effluent, chemical waste, solvent recovery
- Biofuels: Oil extraction for biodiesel, biomass pre-treatment, thermal hydrolysis, fermentation, digestate concentration
- Evaporation (see below)
HRS Heat Exchangers designs a special version of the Unicus Series for evaporation applications. The principle is the same: a shell and tube heat exchanger with scraping rods in the interior tubes. During evaporation, fouling and reduced heat transfer can become a problem for traditional evaporators, such as falling film types.
In contrast the Unicus’ scraping action keeps the heat transfer surface clean and maintains heat transfer high. This allows the Unicus Series to concentrate materials to levels which traditional technologies cannot match. This makes the Unicus Series ideal solution for the concentration of environmental waste where volume reduction is vital. Unicus evaporators can be applied in a multi-effect setup or in combination with mechanical vapour recompression. Vacuum concentration can also be applied with a Unicus evaporator, while the scraped surface operation allows continuous operation and reduces downtime of the plant.
Materials: Shell side: AISI 304 stainless steel; Tube side: AISI 316L stainless steel
Connections: Shell side: Flange; Tube side: clamp / flange
External Finish: Satin or Polished: Product side: <0.8 microns
Design conditions: Shell side: 10 bar(g) / 185 oC; Tube side: 16 bar(g) / 185 oC
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