Furnaces – Process – Incinerating refuse
Reexamination Certificate
1999-04-21
2001-04-10
Ferensic, Denise L. (Department: 3749)
Furnaces
Process
Incinerating refuse
C110S344000, C110S229000, C110S234000, C110S244000, C110S245000
Reexamination Certificate
active
06213033
ABSTRACT:
The present invention relates to a method for treating waste material containing hydrocarbons, wherein said material is supplied to a reactor, gas containing oxygen is supplied to the reactor, said substances are combusted to form solid residue and said solid residue is discharged from the reactor.
In this disclosure waste material containing hydrocarbons means any kind of material containing hydrocarbons (with longer or shorter carbon chain), found in the nature, produced chemically, formed in mineral or mechanical processes, formed through leakings of materials containing hydrocarbon into soil, etc. Especially, the method is directed to treating waste materials, ie. sludges containing heavy liquid and/or solid hydrocarbons, solid incombustible materials, water, etc. Further, the invention provides a method for treating industrial waste materials obtained in thermal treatment of metals and comprising oils, possibly partially oxidized or carbonized, ferrous oxides, and other admixtures; crude oil spills, mixed with solid impurities; slurries and sludges, such as sediments of oil tanks, bituminous sands, etc. Hereafter all such materials are referred to as waste materials.
Waste materials are difficult to process for disposal purposes. The disposal of waste materials through environmentally acceptable incineration, recovering the energy content and recovering their hydrocarbon contents in a processible form by conventional techniques is problematic. Direct incineration of waste materials is usually hampered by their high viscosity and the presence of solids therein, which prevent the application of conventional incineration methods, such as atomization in fuel jets. Isolation of hydrocarbons by distillation is generally energy consuming.
From patent specification JP 51-33486 a method is known for disposal of oxides containing oil by adding them to an agglomeration mixture with further thermal treatment in a rotary kiln. The hydrocarbons are burnt in the process, yielding additional heat, and the iron oxides enter the mixture. This method has relatively narrow applicability, only in some metallurgical processes, and relatively high energy costs if it is used in oil incineration.
From patent specification RU 1090972 a method is known for disposal of wastes containing oil and iron. In this method, liquid waste oils are dehydrated until the fuel contents of 30-95% is attained and are further burnt at a relatively substoichiometric air (0.35-0.65 of stoichiometric oxygen). At the smoke temperature of 950-1100° C., the dehydrated waste is treated with the gaseous combustion products and, after reduction of metal oxides, the gaseous products are afterburnt, the heat of smoke gases being used for dehydration of the waste. The main disadvantage of this method is the stage of water evaporation, which hampers environmental safety of the process and makes the method complicated. Further, the method has a narrow field of economical application.
From the patent specification U.S. Pat. No. 4,957,048 a method is known, wherein crude oil slurries and other slurries containing heavy hydrocarbons are incinerated. The slurries are mixed with diatomite or perlite so as to obtain a friable mass that is further applied to an incinerator type of rotary kiln or a fluidized bed tubular furnace where the mixture is burnt to yield smoke gases and solid residue that is virtually free of hydrocarbons. The solid residue can be recycled for mixing with fresh oil slurries. This method has a number of disadvantages. The use of conventional rotary kilns is associated with high energy expenditure. Apart from that, due to the entrainment of particulates in flue gas flow, the system requires a complicated secondary cleansing for smoke gases involving cyclones and/or scrubbers. Another disadvantage of the rotary kiln embodiment is caused by the unburnt carbon present in solid residues. The latter must be afterburnt in a fluidized bed furnace. When fluidized bed reactors are used, the method is sensitive to the size of particulates, both initially contained in waste oil and added in preparing the mixture.
An object of the present invention is to eliminate the drawbacks of the prior art.
Another object of the present invention is to provide an environmentally safe and energy-efficient method for treating a variety of waste materials containing hydrocarbons.
Another object of the present invention is to provide a method for treating waste material containing hydrocarbons, wherein at least a part of the hydrocarbons may be recovered.
Regarding the features characterizing the invention, reference is made to the claims section.
According to the invention gas or gasifying agent containing oxygen is supplied continuously in the reactor in amounts insufficient for complete oxidation of the waste material, said gas or gasifying agent containing oxygen is supplied so as to pass it through a layer of said solid residue and the gaseous combustion products are passed through a layer of untreated waste material to form a product gas containing hydrocarbons and droplets of liquid hydrocarbons. Accordingly the product gas comprises gaseous combustion products of hydrocarbons. Because of the substoichiometric amount of oxygen, the combustion products comprise carbon monoxide and hydrogen in addition to carbon dioxide and water.
According to an advantageous embodiment, the gas containing oxygen is supplied to the reactor countercurrently to the supply of the waste material so that the combustion zone is formed.
Accordingly, the combustion zone is formed in the middle part of the reactor, that means between the ends of the reactor. The gas or gasifying agent containing oxygen is supplied to the reactor at a point after the combustion zone in the streaming direction and the gaseous products are discharged from a point before the combustion zone in the streaming direction of the waste material.
To enhance the yield of hydrocarbons, in order to promote their evaporation, one can introduce steam into the zone where hydrocarbons are heated by the hot product gas.
In the following, the invention is disclosed with nonrestricting examples referring to
FIGS. 1 and 2
showing schematical flow charts of two embodiment examples, and with Examples 1 and 2.
For implementing the treating process the waste material charged into the reactor
2
is preferably sufficiently gas-permeable. The reactor may e a vertical reactor, in particular a shaft kiln. If the waste material
1
contain enough solid particles of sufficiently large dimension, the waste material
1
can be treated as it is. When the contents of solids of the waste material is low or particle size is too small (so as to hamper gas permeability), the waste material
1
may preferably be, prior to charging into the reactor, be mixed with solid incombustible material
3
that has a melting point high enough to avoid agglomeration; the solid material may be e.g. firebrick pieces. Alternatively, the solid inert material may be charged into the reactor without preliminary mixing with the waste material (e.g., in intermittent layers) if this mode of charging secures sufficient gas permeability and homogeneity on the average of the charge. To secure high gas permeability, the inert material having predominantly pieces size over 20 mm may be used. The experiments carried out have shown that with this size of particles the pressure drop in the charge at the gas flow rate of 1000 m
3
/h of per 1 m
2
reactor cross-section did not exceed 500 Pa/m. This makes is possible to perform a process at low pressure drop in the reactor, this drop may be provided with a fan and not a compressor. Pieces of waste refractory or some special items such as tubular cylinders may be used, as this inert material.
The process may be initiated by injecting into the reactor gas or gasifying agent containing oxygen, preliminarily heated to a temperature over 400° C. The preheated gasifying agent may be supplied during a time sufficient to establish in the reactor the zone of gasification. This zone establishes a result of i
Alkov Nikolai
Foursov Victor
Glazov Sergei
Manelis Georgi
Poliantchik Evgeni
Altera Law Group LLC
Ferensic Denise L.
Fioter Oy
Rinehart K. B.
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