Liquid purification or separation – Processes – Including controlling process in response to a sensed condition
Patent
1995-03-22
1997-03-04
Popovics, Robert J.
Liquid purification or separation
Processes
Including controlling process in response to a sensed condition
210744, 210754, 210765, 210768, 210770, 210783, 210784, 210805, 210912, 134 10, 134 13, 134 28, 134 34, 43 1, 159 473, 95 64, B01D 3700, B01D 5334
Patent
active
056075960
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to processes for burning and/or combustion of solid and/or liquid fuels and more particularly to the treatment of the solid residues generated by such processes in the form of cinders and fly ash.
2. State of the Art
When, for example, household garbage is burnt, approximately 250 kg of cinders and 25 kg of fly ash, which is entrained in the exhaust gases, are generated per metric ton. In other combustion processes the quantity of residues depends on the fuel employed and the proportion of cinders/fly ash depends on the type of combustion. Experience shows that the cinders, although quasi-vitrified, are more or less coated with soluble compounds, for example chlorides and alkaline materials which are soluble in the case of the burning of household garbage. Quenching of the cinders in a cinder pit is intended merely to cool these cinders but not to wash them; in most cases this amounts to adding water to the cinder pit, to compensate for the evaporation and the residual moisture of the cinders. In very rare cases it has been possible to employ a high water flow rate to wash the cinders; the latter have then exhibited good qualities for reclaiming. Furthermore, in household garbage incineration plants it is known to use known processes for removing metal scrap from the cinders and to crush/screen them to give them a particle size making them potentially suitable for reclaiming as highway foundation material or as material for construction. For this reclaiming to be really possible there must be no significant release of soluble components in the presence of water. Good performance is therefore necessary in a leaching test. Utilization of the known washing processes would make this possible, but this would involve a high water consumption.
Fly ash very often also includes a high proportion--which may reach 30%--of easily soluble compounds, including heavy metals. It must therefore be treated before it can be stored definitively in a dump or be reclaimed. Various processes have been proposed for such a treatment. For example, in the case of incineration plants, an electrostatic precipitator is frequently found downstream of the incineration furnace and the recovery boiler, ensuring the trapping of the fly ash followed by a wet purification ensuring the scavenging of the acidic gases, HCl and HF in particular. It has been proposed to employ the acidic purge from such wet purification for treating the fly ash by leaching in an acidic phase. The disadvantage of such a method--besides the introduction of a complex external plant--is the use of a liquid that is rich in solubilized heavy metals and in trace elements scavenged in the wet purification. It is then impossible to obtain good leaching properties of the treated residue, in particular with regard to the total soluble fraction, without high water consumption.
It has also been proposed to introduce this fly ash into the recycled scrubber liquid ensuring the scavenging of the acidic gases. In this method there is no need to introduce a complex external plant but, bearing in mind the characteristics of the scrubbing liquid, it is also impossible to obtain good leaching properties of the treated residue, in particular with regard to the total soluble fraction, without high water consumption.
SUMMARY OF THE INVENTION
The present invention is aimed at eliminating the disadvantages of the known methods and at judiciously employing a small quantity of water and/or of reactants and more particularly at judiciously employing the make-up water needed for the operation of the wet purification of the combustion fumes when the residues originate from a combustion plant equipped with wet purification of the exhaust gas. To do this, the residues to be treated are placed in contact with a washing liquid in an agitated tank and then conveyed in the form of laden liquid towards a dehydration device. Thus washed and filtered, the residues are then rinsed with one or several rinsing liquids. Acco
REFERENCES:
patent: 4000991 (1977-01-01), Melin, Jr. et al.
patent: 4389306 (1983-06-01), Nakanishi et al.
patent: 5045115 (1991-09-01), Gmunder et al.
patent: 5092930 (1992-03-01), Fujisawa et al.
patent: 5403496 (1995-04-01), Kramer et al.
LAB S.A.
Popovics Robert J.
LandOfFree
Processes for the treatment of combustion residues and for the p does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Processes for the treatment of combustion residues and for the p, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Processes for the treatment of combustion residues and for the p will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2143813