Heatec custom built an extraordinary 3-pass heater for the SI Group, headquartered in Schenectady, New York. It is being shipped to their Singapore plant.
It is a thermal fluid heater that employs a fired burner and two helical coils, one inside the other. It is expected to have double the life of other 3-pass heaters while still providing the required amount of heating. To assure its long life, Heatec designed the heater with a flux rate much lower than those usually found in other heaters.
Its lower flux rate means that its helical coils will be subjected to much lower thermal energy—especially radiant energy— than is usual in a 3-pass heater. This also means that thermal fluid flowing inside the coils will have a much lower film temperature. The important benefit is longer life of both the helical coil and thermal fluid. This results in substantial cost savings and less downtime.
To achieve the lower flux rate, the heater has to be somewhat larger than a 3-pass heater with higher flux rates. This could be a drawback where only extremely limited space is available for installation of the heater. However it is often possible to overcome the challenge of limited space by placing the heater in another location. Moreover, a vertical configuration of the same heater would have a very small footprint and might fit in tight places if there is free space above its location.
The accompanying photo shows the heater being loaded at the Heatec factory onto a special tractor trailer that has 13 axles. Because of the unusual length of the rig, the rear end of the trailer is steered by remote control from a chase car, enabling the rig to make tight turns.
The overall length of the heater is about 56 feet. Its width is 11 feet. Its height is almost 13 feet. Ship weight is approximately 124,000 lbs. Assembled weight is approximately 145,000 lbs.
Its burner with an output of 26.2 million Btu/hr heats thermal fluid flowing through the two helical coils inside the heater. The burner operates on either natural gas or waste fuel. The outer coil has a diameter of approximately 9 feet. The inner coil has a diameter of 7-1/2 feet. The heater raises the temperature of the thermal fluid to 460 deg F at approximately 3,800 gpm, an extraordinary flow rate.
The two coils are configured so the burner gases make three passes around the coils. The coils are separated by a small gap. The gases first pass through the inside of the smaller coil, then between the two coils. And finally they pass around the outside of the larger coil and out the exhaust stack. The thermal fluid flows through the helical coils, gaining heat from both radiant and convective thermal energy produced by hot burner gases.
