Process for reforming the fly ash

Patent metadata

Field	Value
Publication number	US-12195407-B2
Application number	US-202016972139-A
Country	US
Kind code	B2
Filing date	Feb 13, 2020
Priority date	Mar 18, 2019
Publication date	Jan 14, 2025
Grant date	Jan 14, 2025

Abstract

A process for reforming the fly ash by heating a raw fly ash powder that contains the unburned carbon and thereby decreasing the content of the unburned carbon, characterized in that (a) as means for heating the raw fly ash powder, use is made of a heating unit that heats the raw fly ash powder by passing it through a heated medium-fluidized bed, (b) a high-temperature gas stream is passed through the heating unit to form the heated medium-fluidized bed and to fluidize and convey the raw fly ash powder that is thrown into the medium-fluidized bed, (c) the flow rate of the high-temperature gas stream is so set that the raw fly ash powder thrown into the heating unit is all heated in the medium-fluidized bed and is taken out from a take-out port provided at an upper part of the heating unit but that the particulate medium forming the medium-fluidized bed is not discharged from the take-out port, (d) the fly ash powder after heated and discharged from the take-out port of the heating unit is introduced into an air classifier where it is separated into a fine powder and a coarse powder, (e) the fine powder separated by the air classifier is recovered as the reformed fly ash, and (f) the coarse powder separated by the air classifier is measured for its content of the unburned carbon and when the measured value is larger than a predetermined threshold value, the coarse powder is introduced again into the heating unit so as to be heated again and when the measured value is smaller than the threshold value, the powder is recovered as the reformed fly ash.

First claim

The invention claimed is:

1. A process for reforming a fly ash by heating a raw fly ash powder that contains a unburned carbon and thereby decreasing a content of the unburned carbon, characterized in that:
a: as means for heating the raw fly ash powder, use is made of a heating unit that heats said raw fly ash powder by passing it through a heated medium-fluidized bed;
b: a high-temperature gas stream is passed through said heating unit to form the heated medium-fluidized bed and to fluidize and convey said raw fly ash powder that is thrown into said medium-fluidized bed;
c: a flow rate of said high-temperature gas stream is so set that a superficial velocity in a column is not less than 0.6 m/sec. and not more than 3 m/sec. and that said raw fly ash powder thrown into said heating unit is all heated in said medium-fluidized bed and is taken out from a take-out port provided at an upper part of said heating unit but that the particulate medium forming said medium-fluidized bed is not discharged from said take-out port;
d: a fly ash powder after heated and discharged from the take-out port of said heating unit is introduced into an air classifier where it is separated into a fine powder and a coarse powder;
e: a fine powder separated by said air classifier is recovered as the reformed fly ash; and
f: a coarse powder separated by said air classifier is measured for its content of the unburned carbon and when the measured value is larger than a predetermined threshold value, said coarse powder is introduced again into said heating unit so as to be heated again and when said measured value is smaller than the threshold value, the powder is recovered as the reformed fly ash;
wherein a classification point of said air classifier is set to lie in a range of 100 to 150 μm.

2. The process for reforming the fly ash according to claim 1 , wherein the coarse powder containing the unburned carbon in an amount that is measured to be smaller than the predetermined threshold value, is recovered by being mixed with the fine powder that is separated by said air classifier.

3. The process for reforming the fly ash according to claim 1 , wherein the threshold value of the content of the unburned carbon is set to lie in a range of 0.5 to 4% by mass.

4. The process for reforming the fly ash according to claim 1 , wherein said raw fly ash powder is heated in said medium-fluidized bed at a temperature of 600 to 1100° C.

Assignees

• Tokuyama Corp

Inventors

• Omura Kohei
• Seki Takuya

Classifications

• B09B3/40

  involving thermal treatment, e.g. evaporation (processes using mineral binders involving a melting or softening step B09B3/29; involving radiation B09B3/50) · CPC title

• B07B7/00 Primary

  Selective separation of solid materials carried by, or dispersed in, gas currents (sieves or filters for separating dispersed particles from gases or vapours B01D) · CPC title

• B09B2101/30

  Incineration ashes · CPC title

• C04B7/45

  in fluidised beds {, e.g. spouted beds} · CPC title

• C04B7/438

  Evacuating at least part of the heat treated material before the final burning or melting step, the evacuated material being used as a cement as such · CPC title