Model Formulation for the Exact Position of Dew Point along a Gas Pipeline

Abstract

Natural gas piping network are often laid under the sea bed, under or above earth surface through places of diverse temperature gradients. In such environments, if the temperature of the flowing stream of gas is below the water or hydrocarbons dew points temperatures condensation occurs. The condensates so formed accumulate at low points in the pipes thereby obstructing flow of gas. Flow obstruction leads to pressure drop along the line. Hydrates can also be formed if there is excessive cooling of the gas due to pressure drop. The end result of this is obstruction of flow or freeze up of the valves, a worst case situation leading to total obstruction of flow. This necessitates the need to find at what point along a pipeline at which condensation will commence after attainment of dew point for natural gas gaseous mixtures. The mathematical models so generated help to determine the dew point of such hydrocarbons mixtures and the extent of the length from the upstream end of the pipeline at which dew point will be attained. To prolong the pipe length or stop attainment of dew point temperature, the pipe is covered with a layer of insulating materials of low thermal conductivity.

Keywords: Mass Flowrate; Specific Heat Capacity; Burial Depth; Convective Heat Transfer; Thermal Conductivity; Residual Heat; Dew Point Temperature; Flow Resident Time.