Process for melting down combustion residues into slag

Details Process for melting down combustion residues into slag Process for melting down combustion residues into slag

1995-12-29

2001-03-13

Lazarus, Ira S. (Department: 3743)

Furnaces

Process

Treating fuel constituent or combustion product

C110S230000, C110S246000, C110S248000, C110S344000, C110S345000, C110S346000

Reexamination Certificate

active

06199492

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a process for carbonizing and then incinerating waste materials, using the waste materials as a source of energy, to reduce the waste materials to slag which can be safely disposed of or reused.
BACKGROUND OF THE INVENTION
Fly ash, filter cake and slag from conventional incinerators, apart from unburned carbon, contain heavy metal compounds and organic hydrocarbons which can be washed out and can thereby become pollutants of water and soil. Legislation throughout the world is tending to require significant reductions in the quantity of such pollutants which can be released over a relatively short time scale so as to reduce the ecological toxic potential of slag and thereby permit safe storage, disposal or reuse. More stringent demands are also being made on other solid residues (e.g., flue dust and flue gas cleaning residues), and those residues which cannot be reused are to be processable into inert residual materials.
In general, the aim of present technologies is to reduce the volume of the non-reusable constituents with a view to keeping as small as possible the unavoidable residual material dumps. Space-intensive, environmentally safe residual material dumping of highly toxic residues proves to be very expensive, particularly if it is necessary to comply with legal requirements concerning long-term safety.
In standard grate furnaces for domestic refuse, it has hitherto not been possible to burn or incinerate at a sufficiently high temperature, quite apart from undesired local heating, such that during burning there is a melting down process of the combustion slag which results in permanent binding of heavy metals and complete burning off of organic or highly toxic compounds. Experience has shown that during slag fluidization the grates tend to be stuck during combustion, or the fluidized slag flows through the gaps in the grates. In other words, neither the presently known combustion processes, nor the plants currently in operation, are suitable for such a procedure. In the few plants involving a combination of a grate furnace with a revolving cylindrical furnace, it has hitherto been impossible to melt down slag because, in the grate furnace portion, total combustion of the waste is sought and achieved, thus leaving insufficient available energy in the revolving furnace portion to melt down the incinerated waste into slag. In addition, the revolving cylindrical furnaces do not have the necessary characteristics and equipment for drawing off the molten slag. Such furnaces are only used for complete burning off of the slag. In some special refuse disposal systems, the waste materials are burned in special refuse revolving cylindrical furnaces at very high temperatures using additional energy supplied from outside sources. In these systems, the slag problem is of a minor nature, but the systems are expensive to construct and operate because of the need for added energy.
SUMMARY OF THE INVENTION
An object of the present invention is to reduce the environmental burden of solid waste materials by providing a process for effectively reducing materials such as solid waste, flue dust, potash and other toxic substances into inert slag.
A further object is to provide such a process in which incinerated materials which would otherwise be environmentally harmful end up as an effectively condensed and bound, environmentally harmless material which can be disposed of, e.g., as a TVA inert residue in accordance with the requirements of the regulations governing waste materials in Switzerland, or instead of being dumped, can be employed for a useful purpose.
Briefly described, the invention comprises a substantially thermally closed-cycle method for melting residual substances from waste material combustion into environmentally inert slag comprising the steps of delivering waste materials to a generator comprising a feed grate and a feed means, in a first, low temperature process, substoichiometrically carbonizing the waste materials in the generator using the energy in the waste material for the carbonizing to produce carbonized material having a high energy content and carbonization gases, transferring all of the carbonized material and carbonization gases from the generator to a furnace with additional air for supporting a high temperature incineration, incinerating in the furnace the carbonized material and the carbonization gases at a high temperature in the furnace without the addition of fuel other than the carbonized material and carbonization gases, thereby forming a slag with substantially no combustible materials therein, collecting heat from the furnace, and returning the collected heat to the generator to enhance carbonizing of materials therein.
The process according to the invention makes it possible to melt down into slag waste materials, flue dust and potash through the energy content of the supplied waste materials. Heavy metal compounds contained in the input materials are immobilized, ignition loss is reduced to a minimum, organic hydrocarbon compounds are lowered to below the present detection limit and specific volumes are greatly reduced. The fundamental idea of the process of the invention is, instead of complete initial incineration or combustion of waste as has heretofore been sought, to initially carry out in a low temperature unit a substoichiometric carbonization of the input material and then, using the carbonized solid materials and the gases which result from the carbonization process, to perform in a high temperature stage a complete combustion or incineration of the resulting materials to cause slag fluidization.
In this process, the materials resulting from the carbonization process contain more combustion energy than the residues resulting from conventional incineration processes and can be supplied to a slag fluidization stage, such a revolving cylindrical furnace, for formation of fluidized slag. Of the energy recovered by gasification, all or part can be supplied to slag fluidization in gaseous form so that the process can be controlled or regulated in a relatively simple manner. The end product of the process is then a completely burned-out, fluid slag which can be allowed to solidify in any chosen form.


REFERENCES:
patent: 4303477 (1981-12-01), Schmidt et al.
patent: 4354440 (1982-10-01), McRee, Jr.
patent: 4794871 (1989-01-01), Schmidt et al.
patent: 4878440 (1989-11-01), Tratz et al.
patent: 5044288 (1991-09-01), Barlow
patent: 5237940 (1993-08-01), Pieper et al.
patent: 5370067 (1994-12-01), Finet
patent: 5425317 (1995-06-01), Schaub et al.
patent: 5497712 (1996-03-01), May et al.
patent: 5592888 (1997-01-01), Berwein et al.
patent: 5724900 (1998-03-01), Tratz
patent: 5826521 (1998-10-01), Schumann et al.
patent: 0 495 766 A2 (1992-07-01), None
patent: 55-140026 (1980-11-01), None
patent: PCT/DK91/00169 (1991-06-01), None
Kunstler et al., The VS-Combination Reactor from Kupat AG, as translated into English by FLS, Inc., 1994.
Kunstler et al., “Der VS-Kombi-Reaktor der Firma Kupat AG”, Mull und Abfall, Issue 31 and 32, pp 67-72, 1994.

Affiliated with

Also associated with

Rating

Process for melting down combustion residues into slag does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for melting down combustion residues into slag, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for melting down combustion residues into slag will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2524733