JPS54143195A - Sulfuric acid sampling method for waste gases - Google Patents

Abstract

PURPOSE: To effectively trap the sulfuric acid content in waste gases by making the waste gases, which contain dusts and gas or mist sulfuric acid, pass through a dust filter at a temperature higher than the freezing point of sulfuric acid so that the dusts may be filtered and by making the gases pass through a spiral pipe and a membrane filter at a temperature lower than the same freezing point.

CONSTITUTION: The waste gases in a flue 1, which are sucked through such a sampling pipe 2 as is heated by a heater 3 at a temperature higher than the freezing point of sulfuric acid and lower than the decomposing point of the same, e.g., about 200 to 300°C, are made to pass through a dust filter (preferably of a cylindrical filter paper) 4 to remove the dusts (whereas the mist sulfuric acid in the waste gases are allowed to pass in the gas state). The waste gases thus treated are then guided into the spiral pipe 7, which is arranged in a glycerin bath 9 and held at a temperature of 150W80°C (which is lower than the freezing point of sulfuric acid), and are made to pass therethrough at a flow rate higher than about 20W15 litters/min so that most of the sulfuric acid content is trapped in the liquid state. The waste gases are then further made to pass through a membrane filter 8 having a pore diameter smaller than about 8 micron so that the remaining mist sulfuric acid may be trapped.

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