US 5,212,144 A · Process for making chemically activated carbon

Abstract

An improved apparatus and method for the manufacture of activated carbon wherein a carbonaceous raw material impregnated with a chemical activating agent is treated by controlling the rate of heat transfer to the particles via indirect heating of the activation furnace and simultaneously introducing a flow of independently controlled sweep gas at spaced intervals along the path of travel of the particles through the furnace to more precisely control the activation reaction and the level of densification of the particles during certain stages of treatment. In a more preferred embodiment, the particles are processed in a plurality of treatment stages related to the rate of evolution of water and/or the evolution of water and the chemical activating agent and the rates of heat transfer and the volume flow rate of sweep gas are closely controlled relative to achieving predetermined levels of densification of the particles during each treatment stage and selected levels of activation properties in the end product.

Claims20

Dependent claims

A process for producing a chemically activated carbon from particles of carbonaceous raw material impregnated with an amount of an activating chemical capable of causing the simultaneous carbonization and activation of said raw material by an essentially dehydration reaction evolving a substantial amount of the water content of said impregnated material, comprising the steps of:

a) feeding said particles of impregnated raw material into a furnace means for travel along the length of said furnace means to an outlet;
b) transferring heat energy from an indirect heating source, independent of the atmosphere in said furnace means, to said particles at a selected rate to raise the temperature of said particles to a value greater than about 120 degrees C. while simultaneously contacting said particles with an independently controlled flow of sweep gas introduced at outlets spaced longitudinally from one another along the path of travel of said particles, the volume flow rate of said sweep gas through said outlets being selected to substantially eliminate the tendency of said particles to adhere to one another or to internal surfaces of said furnace means during travel through said furnace means;
c) thereafter, treating said particles of raw material with heat to complete the carbonization and activation of said particles to produce a useful activated carbon product.

In an improved chemical activation process wherein particles of a carbonaceous raw material are impregnated with a chemical activating agent capable of causing simultaneous carbonization and activation of the particles by an essentially dehydration reaction evolving water from said impregnated particles, the improvement comprising the steps of:

a) passing said impregnated particles through a furnace means having a selected length and an inlet and outlet and provided with means for applying heat energy to said particles during travel through said furnace means from an indirect source of heat in a variable, controlled manner along the length of said furnace means independent of the internal atmosphere in said furnace means, and with means for introducing and exhausting a flow of sweep gas at selected rates at spaced intervals along the path of travel of said particles through said furnace means;
b) varying the application of heat energy to said particles by controlling said indirect source of heat to cause the temperature of said particles to increase between the inlet and outlet of said furnace means to a final temperature greater than about 425 degrees C., said rate of temperature increase selected to cause a predetermined rate of evolution of the volatile constituents of said particles to achieve a selected degree of densification, carbonization and activation of said particles;
c) simultaneously with the controlled application of heat energy to said particles defined in paragraph (b), contacting said particles during their path of travel through said furnace means with a selected volume flow rate of sweep gas introduced at preselected spaced intervals along the path of travel of said particles, said volume flow rate being sufficient to inhibit the accumulation of evolved volatile constituents of the dehydration reaction on the surface of said particles to substantially eliminate adherence of the particles to one another or to parts of said furnace means.

Dependencies are inferred from the claim text.

Process for making chemically activated carbon

Life of this patent

Process for making chemically activated carbon

Life of this patent

Abstract

Claims20