Solvent extraction system and method

A solvent extraction system for purifying contaminated oil, comprising:

• an elongated solvent extraction chamber having a first end, a second end, a length (L) between the first end and the second end, at least one first port and at least one second port;
• a first liquid source containing contaminated oil to be cleaned;
• a first pump in fluid communication between the first liquid source and the at least one second port, the first pump being configured to pump the contaminated oil from the first liquid source into the solvent extraction chamber via the at least one second port;
• a second liquid source containing a liquid separation aid, the liquid separation aid being a polar solution and at least substantially insoluble in the contaminated oil such that the liquid separation aid and the contaminated oil form two phases upon mixing, the liquid separation aid having a different density than the contaminated oil, and having the property of adsorbing and/or absorbing contaminating solids and/or dissolved impurities in the contaminated oil;
• a dispersed phase inlet in fluid communication with a space in the solvent extraction chamber adjacent the first end of the solvent extraction chamber;
• a second pump in fluid communication between the second liquid source and the dispersed phase inlet, the second pump being configured to pump the liquid separation aid from the second liquid source into the solvent extraction chamber via the dispersed phase inlet;
• and
• a membrane having pores, diameters of the pores being from 1 to 100 μm and not differing by more than 20%, and center-to-center distances between the pores being from 10 to 1000 μm and not differing more than 20%, wherein the membrane is positioned in the space in the solvent extraction chamber adjacent the first end of the solvent extraction chamber relative to the dispersed phase inlet such that the liquid separation aid provided into the solvent extraction chamber through the dispersed phase inlet must pass through the membrane before mixing with the contaminated oil;
• wherein the at least one first port is configured to remove the liquid separation aid with adsorbed/absorbed contaminating solids and/or dissolved impurities after having been mixed with the contaminated oil.