JP3483111B2 - Double cylindrical firing furnace and firing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double cylinder type firing furnace for firing lime, dolomite, etc. using waste plastic as a fuel, and a firing method using this furnace.

[0002]

2. Description of the Related Art A double-cylindrical firing furnace is also called a Beckenbach furnace, and its structure is, as shown in FIGS. 3 and 4, that the main body of the furnace is a double cylinder of an outer cylinder 1 and an inner cylinder 2. . The outer cylinder 1 and the inner cylinder 2 are fixed by a plurality of bridges 3 having an arched shape, a wedge shape or the like, and each bridge 3 forms an eaves to block the flow of the rough stone, and a space is formed under the eaves. It is a combustion chamber 4. The rough stones are fed from the hopper 5 at the furnace top to the rough stone feeding device 6
It is introduced between the outer cylinder 1 and the inner cylinder 2 and descends, passes through the pre-tropical zone, the firing zone, and the cooling zone in sequence, accumulates in the hopper 7 at the bottom of the furnace, and is taken out by the product take-out device 8. Fuel such as heavy oil is burned in the burner 9 attached to the outer cylinder 1 in the combustion chamber 4. The combustion air is first sent to the recuperator 11 by the blower 10, where it is heat-exchanged with the exhaust gas to be heated and then used as primary air in each burner 9. The combustion gas passes through the firing zone, rises to the pretropical zone, exchanges heat with the rough stone in the recuperator 11, and is then discharged by the exhaust gas fan 12. Cooling air is sent to the inner cylinder 2 by the inner cylinder cooling fan 13, and the air that has become high temperature by cooling the inner cylinder is 2 of the burner 9.
Used as next air. The fired product is cooled by the air sucked into the furnace at a negative pressure below the furnace, and the air heated thereby and a part of the combustion gas from the lower combustion chamber are returned to the lower combustion chamber by the injector 14. Sent
The inner cylinder 2 also functions as a passage for the circulating gas. In this furnace, the gas flow with respect to the flow of limestone, etc. is countercurrent in the cooling zone, the circulating gas and the combustion gas are cocurrent with the flow of limestone, etc. in the co-current firing zone, and the lower firing zone, the upper firing zone Countercurrent in the pretropical zone.

Heavy oil is mainly used as the fuel for this double cylinder type firing furnace, and in addition to this, gas fuel and pulverized coal are also used.

[0004]

Waste plastic is a new fuel that has recently been drawing attention, and is attractive because it is cheaper than conventional heavy oil and gas.

However, since solid waste plastic is not easily pulverized and is costly, it was not suitable to use it as a fuel in a double cylinder type firing furnace in the same manner as coal or petroleum coke. The present inventors have made various studies in order to develop a method of using this waste plastic as a fuel for a double cylindrical firing furnace. The difficulty of waste plastics as a fuel for a firing furnace is that the state of solid, melting, and gasification changes depending on the temperature to burn, and the change causes a time difference depending on the size. For this reason, when continuously supplying waste plastics having a wide range of sizes, state changes of solid, melting, and gasification are mixed, and the supply line and the injection nozzle are closed. Further, if the solid waste plastic blown into the packed bed is not melted or gasified smoothly, it will start to deposit in the space and will not permeate or diffuse into the rough stone, causing problems such as sooting phenomenon.

An object of the present invention is to solve the above problems and provide a double cylinder type firing furnace and a firing method which can use waste plastic as an inexpensive fuel.

[0007]

As a result of intensive studies to solve the above problems, the inventors of the present invention have newly provided a waste plastic injection port in the fuel chamber and set the waste plastic to an average particle size of 30 mm or less. The temperature of the combustion space is 60
By blowing while maintaining the temperature above 0 ° C, we succeeded in keeping the waste plastic burning smoothly.

Namely, the present invention is made of a double cylinder furnace body fills the rough between the cylinder and the outer cylinder of the double cylinder is mounted is a burner for firing the ore, ore is above the burner In a firing furnace that has an eaves that blocks the flow of water to form a combustion space, burns waste plastic into the combustion space.
A lime or dolomite, characterized in that a blowing port for blowing the entire rough stone surface below the space is provided above the burner of the outer cylinder, and the blown waste plastic is provided at a position where it passes through the flame of the burner. Injecting waste plastic with an average particle size of 30 mm or less while keeping the temperature of the combustion space at 600 ° C or higher, using the double-cylindrical firing furnace for firing rough stones such as And a firing method.

[0009] In the firing furnace described above, when the combustion chamber and rough periphery thereof the upper and lower reaches above heated to 600 ° C. in the auxiliary burner, while applying a solid waste plastics to the frame of the auxiliary burner, preferably combustion Spray so that it is evenly distributed on the rough stone deposit surface below the chamber. In this process, small-sized solid waste plastic melts and gasifies and burns in contact with high-temperature gas, but the large-particle waste plastic lands on the surface of the rough deposits while drawing a trajectory, melting,
It gasifies and diffuses into the packed bed of ore along with combustion air flowing in parallel or countercurrent to the descent of the ore and diffuses completely to burn in the voids.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The waste plastic blowing port has an inner diameter of about 10 to 100 mm, preferably about 30 to 50 mm, depending on the number of bridges, and the installation site is the bottom of the space formed by the eaves bridge, that is, the bridge. It is set so that the waste plastic particles can be blown over the entire upper surface of the limestone which flows from the lower edge toward the center with a repose angle.
Waste plastics are usually blown with gas, often air, as a carrier gas, so many installation sites are possible by varying the blow pressure and angle. However, it is advisable to provide it above the normal fuel burner used as an auxiliary burner so that the waste plastic passes through the flame of the normal fuel burner and falls onto the surface of the limestone. It is also preferable to use the blowing port as a nozzle and swing it vertically or horizontally. The limestone fired in the furnace of the present invention has an average particle size of about 10 to 100 mm, usually about 40 to 60 mm, and an angle of repose of about 35 to 45 °.

The waste plastic may be any one that burns. For example, polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, waste paper, or these two kinds. It is a mixture of the above. If the waste plastic is too large, it is difficult to blow it, and it takes time to ignite, so the upper limit of the appropriate particle size is about 30 mm, preferably 20 mm or less. Although there is no particular lower limit, it is usually 3 mm or more.

The ignition time of the waste plastic varies depending on the type and particle size of the waste plastic, and in the case of a plastic having good flammability such as polyethylene, polypropylene, polystyrene, ABS, etc., the particle size at an ambient temperature of 600 ° C. It is about 50 seconds for 10 mm, about 100 seconds for 20 mm, and about 180 seconds for a particle size of 30 mm. Ambient temperature is 800 ° C
When the particle diameter becomes 10 mm, it takes about 5 seconds, and when the particle diameter is 20 mm, it becomes 10 seconds.
It takes about 20 seconds with a particle size of 30 mm. 800 ℃ for polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, etc.
Then, the particle size of 20 mm is about 20 seconds, and the particle size of 30 mm is about 35 seconds.

A high temperature field is an essential condition (about 600 ° C. or higher) for burning the waste plastic blown into the furnace.
No waste plastic burned at 0 ° C. Therefore, at the time of starting the furnace, first, fuel such as heavy oil, pulverized coal, pulverized coke, kerosene, and LPG is used to raise the temperature in the combustion chamber to 600 ° C. After that, the injection of waste plastic is started, but the inside of the combustion chamber is constantly 600 ° C or higher during operation.
Preferably, heavy oil, pulverized coal, pulverized coke, kerosene, and LPG are used in combination intermittently or continuously as needed so that the temperature can be maintained at 1300 ° C or higher.

The amount of waste plastics supplied is such that waste plastics do not accumulate in each combustion chamber and block voids between limestones or soot is generated. Specifically, the particle size is 30.
One measure is that the amount of waste plastic of 50 mm or less injected for 50 seconds does not fill the space of the combustion chamber.

Waste plastic can be blown into the inner cylinder as well as the combustion chamber. As for the blowing into the inner cylinder, a jacketed blow pipe cooled by water / air is inserted through the lower combustion chamber and the inner cylinder wall, and its tip is directed downward. The waste plastic is injected into the inner cylinder when the temperature distribution in the entire furnace reaches a stable state (equilibrium state). The auxiliary burner which raises the circulating gas temperature is constantly monitored so that the temperature of the combustion chamber is 600 ° C. or higher, and is intermittently or continuously operated with the injection of waste plastic while minimizing the amount of petrochemical fuel.

[0016]

EXAMPLE In the firing furnace shown in FIGS. 3 and 4, a suspension type furnace in which a cylinder was suspended was used. Each combustion chamber 9 was provided with a waste plastic injection port 15 shown in FIGS. The waste plastic blowing port 15 is a nozzle having an inner diameter of 40 mmφ, and the waste plastic is blown into the combustion chamber 4 with compressed air. The average particle size of waste plastic is 10 mm
Of polyethylene was used. The firing conditions and results are shown in the table below.

[0017]

[Table 1]

[0018]

By applying the present invention, it is possible to completely burn the waste plastic even in the packed bed, and by evenly distributing the waste plastic on the surface of the accumulated limestone in the lower part of the combustion chamber, the product can be manufactured by the conventional method. Similar quality is ensured. As a result, by blowing the solid waste plastic, it is possible to significantly reduce fuel consumption.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a waste plastic injection port is provided in a combustion chamber of a double cylinder type lime baking furnace.

FIG. 2 is a cross-sectional view in the direction perpendicular to FIG.

FIG. 3 is a cross-sectional view showing the structure of an example of a double cylinder type lime baking furnace.

FIG. 4 is a perspective view in which a main part of the firing furnace is partially cut away.

[Explanation of symbols]

1 ... Outer cylinder 2 ... Inner cylinder 3 ... Bridge 4 ... Combustion chamber 5 ... Hopper 6 ... Gemstone input device 7 ... Hopper 8: Product take-out device 9 ... Burner 10 ... Blower 11 ... Recapperator 12 ... Waste gas fan 13 ... Inner cylinder cooling fan 14 ... Injector 15 ... Waste plastic injection port

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor No Otani, No. 3-21-6 Highland, Yokosuka City, Kanagawa Prefecture (72) Inventor, Nobuo Katata 2272-14, Fukaya, Ayase City, Kanagawa Prefecture (72) Inventor, Mitsuo Tani, Tochigi 1-34-1 Chuo-cho, Oyama-shi, Oita Prefecture (72) Inventor Masahiro Nakata 8-2, Hachigi-cho, Kuzuu-cho, Ansu-gun, Tochigi Prefecture (72) Inventor Hiroyasu Ito 1089-6, Horieme-cho, Sano-shi, Tochigi Prefecture (56) References JP 56-155048 (JP, A) JP 56-34086 (JP, A) JP 8-337447 (JP, A) JP 7-315896 (JP, A) JP 8 −283053 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 2/10-2/12 C04B 7/44 F27B 1/00-1/28 F27D 7/00-15 / 02

Claims (2)

(57) [Claims] 1. A furnace body is made of a double cylinder filling rough between the cylinder and the outer cylinder of the double cylinder is burner firing the ore is mounted, interrupting the stream of ore is above the burner In a firing furnace with an eaves that forms a combustion space by
Waste plastic is put in the combustion space.
A blow port for blowing the whole is above the burner of the outer cylinder and the blown waste plastic is provided at a position where it passes through the flame of the burner, and rough stones such as lime and dolomite are provided. Double cylindrical firing furnace for firing 2. A firing method characterized by using the double-cylindrical firing furnace according to claim 1, and blowing in waste plastic having an average particle diameter of 30 mm or less while maintaining the temperature of the combustion space at 600 ° C. or more.