Solid particle analysis in crude and vacuum residue

[rumirav]

Dear all,

High content of solid particles in crude oil or Delayed Coker feed can cause accelerated fouling in the furnace.
Has anyone experience on how to measure solid particles concentration and particle size distribution in crude and/or vacuum residue? I have seen the use of laser difraction or particle counter for other products (kerosene, lubricants, etc) to measure both total content and particle size, but I am not sure if this could be succesfully applied to vacuum residue.
What is the maximum solid concentration recommended to avoid fouling issues?
What is the maximum solid particle size recommended?

Thank you in advance for your help

Best regards