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Graham Heliflow - Spiral Tube Heat Exchangers
The Graham Heliflow Heat Exchanger is uniquely designed and engineered to handle difficult heat transfer applications. Graham created the Heliflow to be exceptionally versatile, yielding heat transfer rates that can be more than 40% better than typical shell and tube designs. The Heliflow Heat Exchanger encompasses a spiral coil 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 optimal thermal and hydraulic requirements balance, resulting in maximum heat transfer efficiency. High pressure, specialized materials, cyclic operation, temperature extremes, and other conditions can be handled easily. The Graham Heliflow Heat Exchanger has years of proven service in thousands of applications worldwide, with high-quality performance always guaranteed.
The many advantages of the unique Graham Heliflow make it an efficient heat exchanger for a wide range of applications; some of which include:
- Liquid-to-liquid
- Cryogenic
- High pressure
- Blowdown
- Natural gas heaters
- Vent condensers
- Mechanical seal coolers
- Compressor inter/aftercoolers
- Supercritical fluid
- Feedwater preheaters
- Lethal service
- Steam or process fluid vaporizers
- Boiler or process sample coolers
- Hot water heaters
- High temperature
- Freeze condensers
- Hydraulic/lube oil coolers
The Graham Heliflow is ideally suited for applications with a liquid-to-liquid service requiring a heat exchanger.
When designing the exchanger, the “dirty” fluid should be on the shell side of the unit. The Heliflow makes shell-side cleaning easy. Cleaning can be done in place without breaking shell-side or tube-side pipe connections. The flow pattern is 100% countercurrent, maximizing the temperature differential and thermal efficiency.
Graham has conducted extensive research and development in the area of cryogenic vaporizers. Our research and many years of proven experience in this area confirm that the Heliflow heat exchanger is excellent for cryogenic applications. The unique tube coil of the Heliflow can easily accommodate the large temperature differentials typical in cryogenic units.
Heliflow Heat Exchangers often use cryogenic fluids as the cooling medium; alternately, Heliflows can vaporize fluids, such as N2, O2, CO2, or other fluids. For information on this subject, refer to the Graham article titled Convective flow boiling in coiled tubes. Convective flow boiling in coiled tubes.
High pressure applications are another way to utilize the Heliflow Heat Exchanger. The tubeside of the exchanger does not rely on gaskets for sealing, and can be designed to 15,000 psig. A key advantage that a Heliflow offers is that it has no flat sided pressure bearing surfaces that quickly become thick as design pressure increases.
A Heliflow uses tubing and pipe to contain the tubeside’s usually high operating pressure fluid.
The shellside of the unit can be rated for pressures up to 5,000 psig.
Boiler blowdown and process sample coolers are perfect applications for a Heliflow heat exchanger. The compact size of the Heliflow fits into tight spaces. Also, the Heliflow design can withstand the cyclic nature of blowdown service.
When natural gas is passed through a pressure reducing station, it decreases in temperature. The compact Heliflow design is often used to increase the temperature of the natural gas.
Heliflow Heat Exchanger technology is at the heart of Graham’s vent condensers.
Vent condensers are often used on storage tanks to reclaim products contained in the tank and control the harmful emissions that escape from the tank to atmosphere. During the day, the sun heats the fluid in the tank. The increase in the system’s temperature will cause the vapors in the tank to expand and increase vaporization of the volatile components as their vapor pressures increase. By installing a vent condenser on the vessel, the condensable vapors are reclaimed and refluxed back into the storage tank.
In addition to the venting caused by temperature changes, vapors are exhausted to atmosphere as the tank is filled. The vent condenser experiences the greatest thermal duty when the tank is being filled. The heat exchanger, therefore, should be sized based on the filling case.
Graham has taken the lead in reducing VOC (volatile organic compound) emissions with our design of specialized vent condensers. These units often are used to recover valuable product and reduce the load on downstream pollution control equipment at the same time.
Three styles are available for your choosing:
VCIN
- No casing required, most economical choice
- Typically used for new vessels
- Drop tube can be supplied to reflux condensate below liquid level
- Fits inside a flanged vessel connection
- Typically used on existing vessels
- Does not require additional supporting structure
- Mounts on top of flanged vessel connection
- Corrosive fluid can be placed on the tubeside
- Casing can be lower cost material
- Permits sub-cooling of the condensate