Heat exchangers are a critical part of Process equipment. To work efficiently, they need to fit in perfectly in any processing plant’s ecosystem. That means it needs to be precisely suited to the type of liquid(s) it is used for. Selecting the right heat exchanger involves a thorough review of all the basic parameters and design specifications, that tell you about its competency and its specific area of application.
In today’s time, it’s very easy to get confused with the wide variety of heat exchangers available in the market. From a basic perspective, all heat exchangers perform the same function. But when it comes to optimizing the plant’s production process, heat exchangers need to be selected very carefully.
You may think… Why some heat exchangers are chosen over others? The answer to that is performance!
A heat exchanger is fundamentally designed to perform under very specific settings i.e. for specific ranges of liquid viscosity, temperature, pressure etc. These may even overlap between 2 types of heat exchangers but mostly, they are meant for the thermal processing of only a particular set of products. That’s why, processing plants in various industry domains like food, dairy, chemical or pharmaceutical, work with different heat exchangers.
Distinguishing heat exchangers based on technical parameters:
To get optimum results, one must select a heat exchanger based on 2 aspects; Heat exchanger specifications and fluid properties. Before going into that, you need to understand the basic principle or the basic process of how a particular heat exchanger works.
So we have made a list of different heat exchangers that define each one’s operation process, along with the technical parameters that will help you identify each one as a distinct product.
Here’s a list of 5 different heat exchangers:
- Plate heat exchanger:
Plate heat exchangers use metal plates to transfer heat between two fluids. They are units that are made with a number of corrugated metal sheets or heat transfer plates clamped together in a frame. The adjacent plates are spaced by gaskets, which form a narrow, uninterrupted space through which liquid flows. The fluids are separated by the gaskets and pass through alternate channels. By arranging these channels in groups, several fluid streams can be accommodated at once.
Technical Parameters:
Temperature (oC): 150 to 250
Pressure (PSIG): 150 to 300
Viscosity: less than 20,000 cPs.
Best used for:
Plate exchanger is the most efficient due to turbulent flow on both sides (viscous to viscous liquids). Also, it’s a great option for tight spaces as due to its compactness, efficiency and ease of maintenance. They work with liquids with less than 5% of nonabrasive solids, generally in the micron-size range.
- Shell & Tube heat exchanger:
This heat exchanger consists of a shell (a large pressure vessel) with a bundle of tubes inside it. One fluid runs through the tubes, and another fluid flows over the tubes (through the shell) to transfer heat between the two fluids. The set of tubes is called a tube bundle and may be composed of several types of tubes.
Technical parameters:
Temperature (oC) >500
Pressure (PSIG): >1,500
Viscosity: less than 10,000 cPs.
Best used for:
Due to its peculiar configuration, Shell & Tube Heat Exchangers can be used to transfer heat to a variety of materials, including asphalt and water-based liquids with very low solid content. They heat materials through the use of either hot oil or steam.
- Spiral Heat Exchanger:
The Spiral Plate Heat Exchanger is actually a family of heat exchangers based on the basic Type A spiral core. As the name indicates, it contains a pair of flat surfaces that are coiled to form the two channels in a counter-flow arrangement. Each of the two channels has one long curved path. A variety of spiral heat exchangers can be created by adding or taking away weld-seams and head arrangements.
Technical parameters:
Temperature(oC): up to 900
Pressure(PSIG): > 1500
Viscosity: upto 20,000 cPs.
Best used for:
Spiral systems suitable for a multitude of applications. They can be used for slurries, liquid nitrogen and highly viscous liquids like fatty acids and much more.
- Scraped surface heat exchanger:
This type of heat exchanger consists of a cylinder that has an inner tube and an outside tube. The media flows counter-current to the product, inside an annular space between the two tubes. Inside the inner cylinder, a rotating bladed shaft is positioned concentrically to continually agitate and remove the product from the heat exchange wall areas.
Technical Parameters:
Temperature (oC): >200
Pressure (PSIG): 500
Viscosity: up to 100,000 cPs
- Kettle:
Kettle is a type of a Reboiler heat exchanger, typically used to provide heat to the bottom of industrial distillation columns. They boil the liquid from the bottom of a distillation column to generate vapours which are returned to the column to drive the distillation separation. Kettle Reboilers may require pumping of the column bottoms liquid into the kettle, or there may be sufficient liquid head to deliver the liquid into the Reboiler.
Technical Parameters:
Temperature (oC): >120
Pressure (PSIG): 50 to 75
Best used for:
All types of liquids as it is open tank operation.
Best used for:
Heavy fouling and crystallizing applications. This product works best with liquids with solid contents greater than 75% to normal, and for complex or sensitive products that require gentile processing.
This list will give you a clear understanding of how to go about choosing heat exchangers for various processes. Whether you’re buying a tubular product or a spiral based, you need one that will do justice to the type of liquids you are working with.
Praj Industries is on the leading Heat exchanger suppliers in India. It offers highly advanced and reliable solutions for bioenergy, high-purity systems, Bioethanol Production wastewater treatment and more. To learn more about their products, visit their websiteà www.praj.net
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