Recovery Of Low-Temperature Heat
PURPOSE: To efficiently recover heat energy at a low temperature level, by heating hydrocarbons and water with synthesis gas through a heat exchange type evaporator, in the production of synthesis gas by steam-reforming hydrocarbons.
CONSTITUTION: With reference to methanol synthesis, desulfurized material natural gas (hydrocarbons) from a conduit 2 and hot water from a conduit 4 are introduced to a falling liquid film evaporator 3. The hot water is vaporized by synthesis gas (or waste gas) entering the shell side of the evaporator 3 from an inlet 5 and leaving from an outlet 6, until the material natural gas passing through the tube is almost equilibrated with the water vapor. Next, the evaporator effluent 7 is separated from unvaporized water in a gas/liquid separator 8, supplied with fresh hot water fed from a conduit 9, and recirculated to the evaporator 3 through a circulation pump 10 and the conduit 4. On the other hand, a mixture of natural gas and steam withdrawn from the separator overhead is supplied with steam from a conduit 12 to adjust the concentration and fed to a reformer 16.