ULTRAMAX – The Ultimate Heat Exchanger Performance ‘On a Plate’
11 December 2002
Since their introduction in the 1930s, plate heat exchanger designs have evolved to satisfy the changing needs of process industries, the only drawback is when the process fluids are not compatible with elastomer gaskets. SWEP have now overcome this problem by combining the compact nature and efficiency of a Plate and frame exchanger in a gasket free all-welded plate heat exchanger - The Ultramax from SWEP International PHE.
The plate heat exchanger is acknowledged as one of the most efficient heat exchanger designs. In its most basic form, the plate heat exchanger consists of corrugated metal plates compressed in a frame. Hot and cold media flow on either side of the plate and transfer heat in a fully countercurrent flow arrangement. Each plate is equipped with a double sealing system that keeps the fluids between the channels. The sealing system is selected based on the application and ranges from elastomer gaskets to continuous welds.
The hallmarks of plate heat exchanger operation are high heat transfer efficiency, compact size, design flexibility, low fouling (as a result of plate pattern turbulence) and low lifecycle cost. A typical heat transfer coefficient for a plate heat exchanger may be four to five times higher than that of a shell and tube design, while the compact heat transfer area in a plate heat exchanger results in an efficient design with space requirements as low as 10% of a typical shell and tube design.
Developments in the last 15 years have expanded the applications in which plate heat exchangers can be used. New approaches include wide-gap designs for fouling services, double-wall plates for increased safety, brazed plates and plates designed specifically for condensing and evaporating duties.
The main limitation of the basic plate heat exchanger design is its sealing system. When using elastomer gaskets, the upper temperature limit is approximately 350oF (177oC). Moreover, some chemicals are not compatible with elastomer gasket materials. For the most demanding applications, welded plate heat exchangers offer optimum performance, with welding on every channel, or on alternating channels, depending on application.
The ULTRAMAX™ all welded plate heat exchanger offers all the benefits of a plate-type exchanger but overcomes the limitations of gasketed models. It can operate at very high pressures (maximum design pressure 1,400 psig) and at low and high temperatures (-320 F to 650 F). The ULTRAMAX™ can handle liquids, gases and mixtures of the two. Applications include: high temperature steam, amines, thermal oil, nitrogen, solvents, and other aggressive media not compatible with gasketed heat exchangers. It is also available in a range of standard connection sizes up to 6 inches.
It works in the same was a conventional plate and frame heat exchanger, with alternating channels for hot and cold media and true counter-current flow which offers full LMTD and allows closer temperature approaches, delivering superior performance compared to cross flow designed units.
SWEP PHE’s plate welding technology eliminates conventional continuous side weldments, enabling it to more efficiently accommodate differential thermal expansion, while also reducing manufacturing cost.
Welded plate heat exchangers are now being used extensively in chemically aggressive processes including oil and gas production and refineries; hydrocarbon processing units such as primaries, intermediates and polymers; pharmaceutical and speciality fine chemicals; and inorganic chemicals production such as chlor-alkali or hydrogen peroxide.
A primary use for welded heat exchangers is as an interchanger for heat recovery or absorption-stripping and distillation unit operations. Welded units are also often used as a condenser or reboiler because they offer large cross-flow area, short flow path (low pressure drop) and flexible connection sizes.
