Abstract: This invention provides a variable length membrane module for separation of fluids in solution. The module comprises a series of hollow fiber membranes, a tubing surrounding the series of hollow membranes, an outer steel tube encasing the series of hollow membranes and a pair of nuts arranged to engage the tubing to adjust the length of the hollow fiber membranes to allow proper passage of the fluids therethrough.

Abstract: A process for improving the properties of a hydrogen donor coal liquefaction solvent employed in a coal liquefaction process which comprises separating said coal liquefaction solvent into a first fraction boiling in the range from about 350.degree. to about 675.degree. F., and a second fraction boiling in the range from about 675.degree. F. to about 1000.degree. F., hydrogenating said first fraction at a temperature ranging from about 600.degree. to about 800.degree. F., under a pressure of about 500 to 4000 psig, hydrogenating said second fraction at a temperature ranging from about 600.degree. to 700.degree. F. at a pressure from about 500 to 4000 psig and combining said hydrogenated first and second fractions to provide a coal liquefaction solvent having an increased concentration of hydrogen donor components.