Sample Solution

surrounded by the heated fluid that will vaporize the LNG.
This LNG vaporizing plant works via an intermediate fluid that utilizes heat transfer fluids in a closed loop to transfer heat to vaporize LNG. Three types of heat transfer fluids who are used in the systems are:
Glycol-water
Hydrocarbon based HTF
Hot water
The commonly used fluid is glycol-water, glycol-water has a low freezing point and will not freeze by vaporizing the LNG. These glycol-water IFVs are very compact exchangers (vertical shell and tube design) due to the high heat transfer coefficients and the large temperature approach.
To warm up the glycol-water there are several options, they can use an air heater, seawater heat exchanger, reverse cooling tower and a waste heat recovery unit or fired heater.
Using air for heating will generate water condensate, especially in the equatorial regions. The water condensate is of rain water quality which can be collected and purified for in-plant water usage and/or export as fresh raw water. Conventional air fin type exchanger consists of fin tubes are not designed for ice buildup. With the use of an intermediate fluid such as glycol-water, the glycol temperature can be controlled at above water freezing temperature hence avoiding the icing problems.
Similarly, the reverse cooling tower design, which extracts ambient heat by direct contact with cooling water via sensible heat and water condensation, would require an intermediate fluid. The heat of the cooling water can be transferred to the intermediate fluid by a heat exchange coil.
Seawater may be also be used. However, the use of seawater is more prone to exchanger fouling, and the exchanger (plate and frame type) need to be cleaned periodically. The plate and frame exchangers are very compact and low cost. Typically, spare seawater exchangers are provided for this option.
Fired heater may be used at the costs of fuel expense. For environmental compliance related to CO and NOx emissions, a selective Catalytic Reduction System can be fitted into the flue gas duct of the fired heater.
There are calculations made for the shell and tube vaporizer heated by engine coolant, the complete calculations are displayed in appendix 3. The calculations are based on the W