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Compact technology : Graham Heliflow heat exchanger
Heliflow is a compact , light and efficient heat exchanger that fits into locations where other heat exchangers have difficulty . The Heliflow can work with pressures up to 1000 barg on the tube side and up to 340 barg on the shell side and withstand 260 degrees Celsius temperature difference between fluids . This equipment is versatile thanks to its wide range of material options and can therefore suit many application requirements . It is designed for a 100 % counter-current flow and close temperature approach can be maintained .
Article written in conjunction with Graham ’ s UK representative : Kinder-Janes Engineers Ltd
The Heliflow heat exchanger encompasses a spiral coil , comprised of multiple parallel tubes mounted within a casing . The case / coil construction creates a spiral flow path providing true counterflow . Each application is specially engineered for an optimal balance of thermal and hydraulic requirements , resulting in maximum heat transfer efficiency . High pressure , specialized materials , cyclic operation , temperature extremes and other conditions can be handled without a problem . The Graham Heliflow heat exchanger has years of proven service , in thousands of applications throughout the world .
Coolers or heaters The tubes in the Heliflow are arranged in parallel , starting with an inlet manifold on one end , and terminating at an outlet manifold on the opposite end . The tube bundle is wound into a helical pattern . This coiled construction creates a spiral flow path for the fluid inside the coil . Each tube is in close contact with the tube above and below it . The coiled tube bundle fits into a two-piece casing . When the casing is tightened , it is designed to slightly compress the tubes . Because of the tight fit , the shell side fluid is forced to circulate in a spiral pattern created by the open spaces between the coils . The seal or process fluid is typically handled on the tube side , while the cooling medium is on the shell side . The tube side can easily be rated for pressures above 70 barg . Standard construction materials include stainless steel for the tube bundle and carbon steel or cast iron for the casing . Copper-nickel and high alloy options , such as duplex stainless steel , are also commonly specified for Heliflow Seal Coolers . Available codes of construction include
Possible construction materials :
- tube side : Copper , stainless steel , admiralty , titanium , cupro-nickel , inconel , duplex stainless steel , monel , steel , other exotic materials . - casing material : Cast iron , cast carbon steel , fabricated carbon steel , stainless steel , cupro-nickel , hastelloy and other exotic materials . - connections : NPT , butt weld , flanged , victaulic , ring joint , others customised .
Figure 1 : Heliflow coil and manifolds
ASME Section VIII , Div 1 , PED and CRN . Heliflow Seal Coolers offer high operating reliability . The effects of fouling are minimized by the turbulent flow and mixing induced by the spiral fluid passages . The casing of the unit can easily be unbolted and removed , which allows for the thorough cleaning of the coolant side without the need to disturb the process piping . The removable casing also allows for quick and easy replacement of the tube bundle , if necessary . The spiral tube bundle eliminates the thermal expansion problems as the bundle is allowed to expand and contract without stressing the tube-to-tube sheet joints .
Heliflow applications : High pressure applications The Heliflow heat exchanger is a very efficient choice for heat transfer applications involving high pressure streams on either the tube side , shell side , or both . The unique spiral coil design allows the tube side , which doesn ’ t rely on gaskets for sealing , to accommodate pressures to 1000 barg without excessive material thickness or difficulty in manufacture . In most high-pressure applications a single process stream is at elevated pressure while the utility stream uses a reduced , nominal pressure fluid . The high-pressure stream is directed to the tube side where , using the application ’ s required alloy , the coil design will mitigate the use of heavy wall components . In addition , due to the relatively small size and circular shape of the shell , it is possible to custom design units that can accommodate shell side pressures up to 340 barg . The Weld Seal shell design eliminates the gasketed shell joint and reduces the size and weight of the unit when accommodating a high-pressure shell side stream .
Feed water pre-heaters This technology can save energy as a heat recovery economiser . Waste heat is recovered and utilized to preheat incoming make-up water that is used in boilers or for other applications . www . heat-exchanger-world . com Heat Exchanger World November 2022
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