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A Wide Range of Applications
TEi-Struthers Wells is a major supplier of circulating thermal fluid heating systems, with about 1000 installations over the past 40 years. These systems are designed to provide high-temperature heat at relatively low pressures to a wide variety of process users such as heat exchangers, reboilers, kettles, autoclaves, calciners, dryers, and synthetic fiber extrusion presses. In a thermal fluid system, a heat transfer fluid is heated to elevated temperatures and then transfers heat to process users by either condensing vapor or liquid-phase heat transfer.
TEi-Struthers Wells has provided heaters for every heat transfer fluid type available, ranging from mineral oils at lower temperatures, to synthetic fluids at elevated temperatures (Dowtherm®, Therminol®, Syltherm®, and others), to inorganic fluids such as molten salt and liquid metals for the highest temperature applications.
Heat duties for fired systems typically range from 3.4 million Btu/h (1.0 MWt) to our largest installation of 121 million Btu/h (35 MWt) in a single heater.
Horizontal packaged heater with serpentine radiant coil and finned tube economizer burns multiple fuels, including waste solvents, and provides 8 million Btu/h (2.9 MWt) at high efficiency. (Expansion tank and pump skid-mounted separately.)
Three forced-circulation vaporizers each generate 54 million Btu/h (15.8 MWt) of biphenyl-diphenyloxide vapor at 684°F (362°C). All three are tied to a common separator drum (flash drum) shown at left.
An Optimum Heater Type for Every Application
At TEi-Struthers Wells we offer a wide range of heater types, so you can be assured that the thermal fluid heater we propose will be the best choice for the application, not merely the type we can fabricate at the least cost. We offer the following types of heaters:
• Vertical, cylindrical heaters with serpentine (hairpin) coils or helical coils. Serpentine coils are offered with optional coil drains and are the workhorse of the industry, offering the most rugged and flexible design. Helical coils are inherently drainable and are preferred for freeze-prone liquids such as molten salt or liquid metals.
• Horizontal serpentine coil heaters. These heaters ship as skid-mounted assemblies with key items accessible from grade level for easy inspection and maintenance. Horizontal serpentine coils are inherently drainable, so they are ideal for difficult fluid applications. These horizontal heaters are usually the first choice when sufficient plot area is available.
• Cabin heaters with horizontal or vertical tubes. Cabin heaters are typically used in larger sizes that cannot be shipped in one shop-assembled piece. This design often lends itself well to modular design for quick field assembly.
• Convective heaters with a combustion chamber and flue gas recirculation. These heaters provide controlled, uniform heat flux profiles in cases where fluid film overheating may be a concern. (See back cover.)
All our thermal fluid systems are available with high-efficiency crossflow convective tube banks.
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Combustion air preheaters can be used to boost efficiency to 90%+, even in high-temperature fluid applications. We offer air preheaters in a variety of types, optimized to the particular fuel(s) being burned. We design and manufacture shell-and-tube exchangers, crossflow tubular exchangers, and heat pipe exchangers to meet any need. We also offer cast iron and glass tube air preheaters for special applications.
All of our designs are available with on-line cleaning by sootblowers for dirty fuel applications, unlike some multipass helical coil designs that must be shut down for water washing or steam cleaning.
Finally, our vertical heaters occupy the smallest possible footprint area, with all components (burner, radiant section, convective section, air preheater, stack) oriented vertically for direct upflow of flue gas from burner to stack. This arrangement saves valuable plot area and allows the stack to be integral to the heater instead of requiring a separate free-standing stack mounted on the foundation.
Packaged thermal fluid heating and cooling system.
Vapor Systems & Hybrid Liquid-Vapor Systems
Systems utilizing condensing organic vapors can have significant advantages over circulating liquid systems, especially where the process requires uniform heating at relatively high temperatures. Because condensation occurs at constant temperature, utilizing the full latent heat of the fluid, circulation rates and pumping costs can be substantially lower in vapor systems than in liquid systems.
Skid-mounted thermal liquid heater burns natural gas and three waste fuels simultaneously. Capacity: 27 million Btu/h (7.9 MWt). Integral air preheat system provides 91% fuel efficiency even with fluid operating at 650°F (343°C).
TEi-Struthers Wells pioneered the development of the forced-circulation vaporizer concept for organic fluids. The
TEi-Struthers Wells design has become the technology of choice, particularly for system operating temperatures in range of 640°F (338°C) to 750°F (400°C). By using high-velocity circulation, positive assurance of equal flow to all tubes, and conservative heater design, our forced-circulation vaporizers absolutely minimize fluid film temperatures and require dramatically less pumping power than competitors’ designs. The result: maximum reliability, maximum fluid life, and lower operating costs.
We have also developed and supplied combination liquid and vapor heating systems utilizing both circulating liquid and vaporization. These hybrid systems have distinct advantages in processes with multiple heat users where both tubular coils and jacketed vessels are employed. Our process engineers are ready to help you choose the optimum system for your specific plant needs.
Large vertical radiant-convective heater is shipped pre-assembled for rapid field installation.
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