Abstract: A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

Abstract: There is described an improved SRC reactor quench system using a condensed product which is recycled to the reactor and provides cooling by evaporation. In the process, the second and subsequent reactors of a series of reactors are cooled by the addition of a light oil fraction which provides cooling by evaporation in the reactor. The vaporized quench liquid is recondensed from the reactor outlet vapor stream.

Abstract: There is described an improved coal liquefaction quenching process which prevents the formation of coke with a minimum reduction of thermal efficiency of the coal liquefaction process. In the process, the rapid cooling of the liquid/solid products of the coal liquefaction reaction is performed without the cooling of the associated vapor stream to thereby prevent formation of coke and the occurrence of retrograde reactions. The rapid cooling is achieved by recycling a subcooled portion of the liquid/solid mixture to the lower section of a phase separator that separates the vapor from the liquid/solid products leaving the coal reactor.

Abstract: A process for producing nitrogen which comprises removing all or substantially all carbon dioxide and water vapor from air, introducing said air at between 85 and 125 psia and below -260.degree. F.

Abstract: A heat exchanger or regenerator system useable in an air separation plant to minimize infiltration of air into the low pressure nitrogen stream comprising a heat exchanger (regenerator) having at least one flow path for the reversing heat exchange fluids, which flow path has at each end, an inlet branch and an outlet branch, wherein each branch has two series connected valves with a vent pipe between each pair of valves. Fluid flow through the vent pipe is controlled, e.g. by remotely actuable switch valves.