Furnaces – Process – Incinerating refuse
Patent
1986-03-20
1986-12-23
Favors, Edward G.
Furnaces
Process
Incinerating refuse
F23G 500
Patent
active
046305556
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a process and an apparatus for incinerating waste products.
An increasing number of industrial firms or tertiary industries are at present equipped with apparatus for incinerating waste products. The use of such apparatus or incinerators may satisfy a legal obligation (hospitals, slaughter-houses, etc. . . . ) or a desire to achieve an energy valorization of these waste products (supermarkets, etc. . . . ). These apparatus must permit a non-polluting, rapid and economical incineration.
There are at present on the market several types of incinerators whose operation is based on different principles. Among these apparatus, there exist the type employing a continuous charging for treating very large quantities of waste products and the type employing a discontinuous charging for treating charges of small volume. The present invention relates to improvements in the latter type of incinerator. The treating capacity of such apparatus and the operating cost obviously depend on the rate of incineration of the waste products. However, when the combustion of the waste products occurs too rapidly, the temperature of the hearth rises considerably and produces, in addition to an accelerated wear of the refractories, considerable pollution at the outlet of the incinerating apparatus. Indeed, theory and practice show that the content of carbon monoxide in the smoke issuing from the incinerator increases with increase in the temperature of the hearth.
It is known from French Pat. No. 2,316,542 to introduce in a continuous manner waste products in a furnace and to incinerate these products, thereby producing gases above the hearth containing a large amount of carbon monoxide. After the creation of this carbon monoxide, secondary air and water are injected in contact with this smoke so as to produce a post-combustion of the smoke gases and catalytically accelerate the oxidation of the CO in accordance with the reaction of water gas.
Now, the applicant has found that such a process applied to the incineration of charges introduced in succession in the incinerator did not permit a correct elimination of the carbon monoxide and the soot from the smoke which issues from the incineration furnace. Indeed, in order to insure that the reaction of post-combustion of the smoke and of catalytic oxidation of the CO is produced, the smoke must be brought to a temperature on the order of 900.degree. C. to 1000.degree. C., as mentioned in said French patent.
Consequently, as soon as the charge is introduced in the furnace, the hearth must be brought to a temperature on the order of 900.degree. C. to 1000.degree. C. so that the smoke immediately has this temperature and the reaction can take place. Now, it has been found by analysis of the smoke gases that, in fact, if the waste products are introduced at this temperature, a very large quantity of carbon monoxide would be produced.
The applicant believes that the combustion of the waste products in the region of the hearth produces pyrolysis gases of the type Cn Hn which form a cloud above the hearth which comprises in succession, in starting at the hearth, a first layer of gas mainly containing hydrogen, with which soot (carbon particles) is mixed, a second layer of gas mainly containing carbon monoxide and hydrogen, and a third layer of gas mainly containing a mixture of CO.sub.2 and H.sub.2 O (pyrolysis gases oxidized with air) in contact with the air of the hearth. This last layer forms an envelope around the second and first layers which cannot be oxidized in the air of the furnace. The method disclosed in said patent consists in injecting air into this cloud so as to try to oxidize the gases of the second and first layers. But if it is desired to obtain an intimate contact between the air and these gases, a large quantity of air must be injected so as to create a turbulence and facilitate the oxidation. The temperature of the smoke will thus be reduced (unless the air is pre-heated, which would be particularly complicated). The temperatur
REFERENCES:
patent: 2829610 (1958-04-01), Paskowski
patent: 4354440 (1982-10-01), McRee, Jr.
patent: 4444127 (1984-04-01), Sprohz
patent: 4481891 (1984-11-01), Takeshita et al.
Guillaume Paul
Kayser Didier
Propice Jean
Favors Edward G.
L'Air Liquide
Robinson, Jr. Lee C.
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