The Adhesion Strength of Semi-Clathrate Hydrate to Different Solid Surfaces

Abstract

The adhesion between a hydrate and a pipe wall is the main cause of hydrate deposition and blockage. In this study, the adhesion strength of semi-clathrate hydrate (tetrabutylammonium bromide hydrate) to four kinds of solid surfaces (E235B carbon steel, E355CC low alloy steel, SUS304 stainless steel, and polytetrafluoroethylene) was measured. This investigation reveals that the adhesion strength of the hydrate to a solid surface is negatively correlated with the wettability of the solid surface, which suggests that hydrophobic materials effectively reduced the hydrate adhesion to the pipe wall. The surface roughness showed different effects on the adhesion of the hydrate to hydrophilic or hydrophobic surfaces. To be specific, when the surface roughness increased from 3.2 µm to 12.5 µm, the hydrate adhesion strength to the hydrophilic surface of SUS304 increased by 123.6%, whereas the hydrate adhesion strength to the hydrophobic surface of polytetrafluoroethylene only increased by 21.5%. This study shows that low wettability and low surface roughness effectively reduce the critical rate required to remove hydrate deposition, which achieves the self-removal of hydrates. At the same time, it was found that the adhesion strength of the hydrate to surfaces increases with increasing subcooling. This investigation holds significant theoretical implications for designing self-cleaning surfaces for oil and gas pipes.