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US 4,228,139 AGranted
Flue gas scrubbing process using fly ash alkali
AssigneePeabody Process System, Inc.
InventorCarlton A. Johnson
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AssigneePeabody Process System, Inc.
InventorCarlton A. Johnson
Estimating the term…
There is disclosed a fly ash utilization system and process for the removal of sulfur dioxide from the flue gas of coal fired boilers. The principal features of the invention are the maintaining of high ionic concentration in a closed loop, water balanced system which is operated at a low pH, i.e. less than 4 and preferably less than 3. The ionic concentration of the scrubber slurry is maintained at at least 5,000 parts per million of alkali metal cations, preferably over 10,000 parts per million, at least a substantial portion of which has been leached from fly ash. The ionic concentration of the scrubber slurry is maintained at a high level by either providing small diked areas in a waste pond for settling of undissolved solids wherein the returned supernatant has a high ionic concentration. A thickener and filter system may also be used to recover high ionic concentration supernatant for return to the scrubber. A principal advantage of the system is that there is a substantially reduced liquid-to-gas ratio required for scrubbing SO.sub.2, with substantial savings in pumping and power requirements for the system.
The process of utilizing fly ash for the removal of sulfur dioxide from flue gas comprising the steps of
The process for the utilization of fly ash for the removal of sulfur dioxide from flue gas comprising the steps of
The process of the utilization of fly ash for the removal of sulfur dioxide from flue gas comprising the steps of
In the removal of sulfur dioxide from flue gas wherein the flue gas is contacted with a scrubber slurry having at least several different alkali metal cations extracted from fly ash by acid leaching of the fly ash in the scrubber slurry and contacting the flue gas with a scrubber slurry having a pH of about 4 or less, the improvement comprising the maintenance of an ionic concentration of at least about 10,000 ppm or greater by returning scrubber slurry supernatant from a waste reservoir having a relatively small volume whereby the high ionic concentration of the supernatant liquid is maintained while solids are removed from the system.
Dependencies are inferred from the claim text.