Furnaces – Process – Incinerating refuse
Patent
1987-07-28
1988-09-06
Favors, Edward G.
Furnaces
Process
Incinerating refuse
110216, 110345, 422169, F23J 1100
Patent
active
047684488
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process and to an installation for carrying out this process, for the purpose of optimally recovering thermal energy from residues and waste.
The invention relates more especially to the treatment of residues and waste of agricultural or industrial origin as well as waste of urban origin such as household refuse.
The treatment of household refuse by incineration with a view to producing thermal energy, and of industrial or agricultural waste, is one of the ways allowing on the one hand energy saving and on the other hand the evacuation of polluting waste.
However, the treatment of waste by incineration raises numerous problems, particularly from the standpoint of ecology.
In fact, incineration ovens supplied with various waste, particularly in the case of household refuse, lead to burning by-products in bulk which are difficult to separate, such as products of synthetic origin; now, these latter deliver in the combustion gases an appreciable proportion of corrosive acid vapours.
These corrosive vapours cannot be rejected into the atmosphere and it is therefore necessary, in order to avoid this drawback, to provide either gas dilution or fume washing installations.
However, although these installations allow rejection into the atmosphere of fumes freed of an excessive percentage of noxious vapours, they produce acid water which must then be treated chemically before being able to be rejected into the environment.
And under these conditions, the installations proceeding by incineration of waste are limited economically due to the problems of pollution that they in turn raise and which must be solved.
The invention relates to an original process presenting the advantage of providing neutralization of the acid vapours escaping in the combustion gases, consequently allowing rejection of these gases into the atmosphere without creating as polluting by-products the presence of acids in liquid phase which would previously have to be chemically neutralized.
To that end, the invention relates in the first place to a process for the exploitation of residues or waste of industrial, agricultural or urban origin, with a view to exploiting the calorific power of these residues and proceeding by incineration thereof in a combustion furnace serving at least one heat exchanger for the production of thermal energy in the form of high-temperature heat-transfer fluid, and the process is characterized in that the combustion vapours and fumes laden with anhydrides and acids are neutralized after passage in the exchanger by the counter-flow encounter with a flow of a neutralizing liquid of basic pH constituted by a slurry formed on the one hand by water and on the other hand by the ashes coming from said combustion furnace and placed in suspension and/or solution in said aqueous phase.
According to one development of the invention, the fumes leaving the neutralization phase are subjected to condensation in order to eliminate the water vapour, the water coming from this condensation being recovered in order to constitute with the ashes the neutralization slurry.
According to another characteristic of the process, the residues constituting the starting raw material are subjected to an operation of granulometric separation, for example in a sieve drum with a view to eliminating the finest particles constituted mainly by organic matter, only the coarser elements forming the oversize and constituted by inert combustible matter being used for supplying the incineration furnace.
And according to another characteristic, the phase of condensation of the purified fumes is provided with recycling of the hot water coming from condensation of the vapours below the dew point and this water is recycled in order to encounter, in counter-flow, the purified vapours, the hot water supplying before its recycling at least one low-temperature heat exchanger to which it transfers its calories.
The invention also relates to an installation for carrying out the process, this installation comprising an incineration furna
REFERENCES:
patent: 4344920 (1982-08-01), Isserlis
Bonhomme Michel
Desplat Philippe
Nobilet Bernard
Favors Edward G.
Propiorga
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