Furnaces – Process – Treating fuel constituent or combustion product
Reexamination Certificate
2000-01-21
2001-05-15
Ferensic, Denise L. (Department: 3749)
Furnaces
Process
Treating fuel constituent or combustion product
C110S218000, C110S219000, C110S220000, C110S235000, C110S346000, C266S197000, C075S471000, C264S917000, C264S574000
Reexamination Certificate
active
06230634
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of blowing a synthetic resin into a furnace and an apparatus therefor.
2. Description of the Related Art
The quantity of waste synthetic resins such as plastics as industrial waste and general garbage has recently been increasing, and disposal thereof has become an important social issue. Particularly, plastics, which is a macromolecular hydrocarbon compound, produces a high calorific value during combustion, and cannot be disposed of in a large quantity because of damage to an incinerator upon incineration, so that it is the current practice to dump most of waste plastics onto a reclamation site for waste. However, the dumping of plastics is not desirable from the environmental point view, and there is an increasing demand for development of a quantity disposing method thereof.
Under such circumstances, methods using synthetic resins such as plastics as an auxiliary fuel for blast furnace are disclosed in European Unexamined Patent Publication No. 0622465A1 and Japanese Patent Publication No. S51-33493. These methods comprise blowing milled synthetic resins as a fuel into a blast furnace through tuyeres: the former method, for example, sets forth substantial conditions of the milled synthetic resin to be blown into the furnace including a particle diameter within a range of from 1 to 10 mm and a bulk density of at least 0.35.
As a result of repeated experiments and studies, however, the present inventors found the existence of the following problems involved in the use of synthetic resins such as plastics (hereinafter the description will be based on “plastics” as a typical example) as a blown fuel for a blast furnace.
Plastics rejected as industrial waste or general garbage, when viewed in terms of form, are broadly divided into lumpy plastics taking a plate shape in general and film-shaped ones. The latter ones, film-shaped plastics, account for a considerable part among rejected plastics. However, because of very low transferability and fluidity of milled film-shaped plastics, there is a serious problem in handling when using them as a fuel. More specifically, when blowing plastics into a blast furnace as a fuel, it is the usual practice to cut plastics stored in a storage silo and pneumatically feed cut plastics into the blast furnace. Because of a very low fluidity of film-shaped plastics, milled plastics containing much film-shaped plastics easily produce bridges (scaffolding) in the storage silo, and any problems involving inability to cut out milled plastics in a constant quantity from the storage silo occur frequently. Further, film-shaped plastics clog the cutting port of the storage silo or the interior of a pneumatic feed pipe (particularly at bends and proximity of valves), leading to a serious problem of frequent occurrence of any problems preventing pneumatic feed to the blast furnace.
Unless these problems are overcome, therefore, it is practically impossible to use film-shaped plastics as a fuel to be blown into a blast furnace or the like. In view of the present circumstances of film-shaped plastics accounting for a major portion of waste plastics as a whole, it is clear that advantages of quantity disposal and effective utilization of waste plastics would be lost unless it is made possible to use film-shaped plastics.
In order to blow plastics as a fuel into the blast furnace, furthermore, it is necessary to use milled plastics to ensure a sufficient combustion property. There is however a limitation on the particle diameter acceptable for milling in terms of treatment cost. A particle diameter within a range of from about 1 to 10 mm is therefore a limit for granulation as is shown in the conventional art. When using lumpy plastics milled to this particle diameter, a sufficient combustion property may be unavailable within the blast furnace. As a result, unburned plastics adhere to each other in the bed coke, thus seriously impairing permeability through the furnace, and may cause trouble in the blast furnace operation.
Milled lumpy plastics take an irregular and angular shape. Ones having a particle diameter of from 1 to 10 mm are therefore low in discharge property upon cutting out from a storage silo and in fluidity and transferability when pneumatically feeding to the blast furnace, leading to easy occurrence of clogging at the cutting port of silo or in the middle of the pneumatic feed pipe system.
It is therefore very difficult to use waste plastics as a fuel to be blown into a blast furnace in an industrial scale by any of the methods proposed by the conventional arts: simply milling plastics into a particle diameter of from 1 to 10 mm processing the same into granules having a high bulk density and blowing the same into the blast furnace.
SUMMARY OF THE INVENTION
The present invention has an object to provide a method of blowing synthetic resins, which permits supply of waste synthetic resins as a blown fuel into a furnace, irrespective of the form thereof, and allows improvement of transferability and combustion property of synthetic resins supplied to the furnace, and an apparatus therefore.
To achieve the above-mentioned object, the present invention provides a method of blowing a synthetic resin material into a furnace, comprising:
(a) a step of classifying synthetic resins into film-shaped synthetic resins and other non-film-shaped synthetic resins;
(b) a step of processing classified film-shaped synthetic resins into a first granular resin material;
(c) a step of crushing non-film-shaped synthetic resins and processing the same into a second granular synthetic resin material;
(d) a step of pneumatically feeding the first granular synthetic resin material and the second granular synthetic material; and
(e) a step of blowing the pneumatically fed first granular synthetic material and second granular resin material into a furnace.
The foregoing process of processing the film-shaped synthetic resins into the granular synthetic resin materials may comprise:
a step of melting or semi-melting the film-shaped synthetic resins by heat; and
a step of solidifying the film-shaped synthetic resins in a molten or semi-molten state.
The method of blowing the synthetic resin material into the furnace of the present invention may further comprise:
a step of separating and removing a chlorine-containing macromolecular resin material from the film-shaped synthetic resins, the film-shaped synthetic resins after separation and removal of the chlorine-containing macromolecular resin material being processed into a granular synthetic resin material in step (b); and
a step of separating and removing the chlorine-containing macromolecular resin material from the non-film-shaped synthetic resins, the separation and removal step being carried out after step (c)
In the method of the present invention, the classifying step, the step of processing the film-shaped synthetic resins and the step of processing the non-film-shaped synthetic resins may be as follows:
the classifying step may comprise classifying the synthetic resins into a film-shaped synthetic resin material, a solid synthetic resin material and a sheet-shaped synthetic resin material, the sheet-shaped resin material being an intermediate form between the film-shaped synthetic resin material and the solid synthetic resin material;
the step of processing the film-shaped synthetic resins may comprise: a step of crushing the film-shaped synthetic resin material into small film pieces; and a step of applying a melting and solidification/granulating treatment to the small film pieces, thereby preparing first synthetic resin particles;
the step of processing the non-film-shaped synthetic resins may comprise:
a step of crushing the solid synthetic resin material,
thereby preparing second synthetic resin particles;
a step of crushing the sheet-shaped synthetic resin material,
thereby preparing small sheet pieces having a maximum size smaller than the maximum size of the small film pieces; and
a step of supplying a melting a
Ariyama Tatsuro
Asakawa Yukihiko
Asanuma Minoru
Fujii Mitsuhiro
Ishiguro Hiroki
Ferensic Denise L.
Frishauf, Holtz, Goodman, Langer & Chick, P.C
NKK Corporation
Rinehart K. B.
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