Hydrocarbon Chemical Reaction Fouling – Crude Oil Test Fouling Mitigation Studies

Reaction rates are heavily dependant on temperature, in general described with Arrhenius approach. Reaction rates are a function of the residence time that the process liquid is exposed to temperatures higher than the cracking temperature of the fluid.

Experiments used light Arabian crude, Watson factor = 11.4. Parallel tubes, plain (control) and enhanced (hiTRAN Elements) were tested under similar conditions. Substantial and sustained fouling reduction was measured.

Advantageous effects:

• Lower tube-wall temperature for same duty
• Reduction in fluid volume which is heated above bulk temperature
• Reduction in wall fluid residence time
• Suppression of nucleation at the surface
• Increased shear rate at the wall (higher removal rate)

Acknowledgement for support: University of Bath, UK

PARTICULATE FOULING

With increased wall shear and fluid mixing generated by the annular flow mechanism, hiTRAN Elements provide a high level of turbulence that mitigates particle deposition.

In laboratory tests, a laser-based method of measurement and time-lapsed photography was used to quantify the rate of sedimentation and the thickness.

Experiments using 50 micron particles (particle density 2500kg/m3) in water glycerol suspension was tested over a range of Reynolds Numbers. Vortices behind the wire loops cause turbulent mixing, resulting in the rate of particle removal being significantly higher than the rate of deposition. Even at low velocity particles remain suspended.

Photographic Evaluation of hydro-dynamics
Talcum as suspension particles, 40 to 60 microns, 2500kg/m3 
Constant Re no. of 750

• High shear rate at the wall causes homogeneous distribution of particles
• Vortexes behind the wire loops causes high liquid mixing

Acknowledgement for support: University of Edinburgh, Scotland

Read complete article on Calgavin research Centre