Abstract
Indirect line heaters are used in gas production, storage, and transmission systems to boost gas temperature in order to facilitate transmission efficiency and reduce problems from water condensation and hydrates. Heat transfer efficiency in these systems is governed by conduction and convection forces, which are determined by the thermophysical properties of the fluids. An ethylene glycol/water mixture is the most common heat transfer fluid used, but it and propylene glycol suffer from less than optimal heat transfer efficiency. Glycols have low thermal conductivities and high viscosities, which degrade thermal performance, and they can have environmental and toxicity issues which limit their use in some applications.
A novel heat transfer fluid has been developed that offers both better heat transfer efficiency and a safer environmental profile than glycol systems. This fluid has individual thermophysical properties that are better than glycol systems, and may provide reduced fuel usage and higher throughput in line heaters. In addition, this new fluid is environmentally safe, being highly biodegradable if discharged, but having a low oxygen demand, reducing the chance of fish kill. The fluid is inhibited for prevention of corrosion, can be formulated for low freeze points, and is expected to be readily serviceable and stable for long life. This paper presents an analysis of the heat transfer process, a comparison of the novel fluid with glycols, and data from an initial pilot test of the system.
