JP5550664B2 - melting furnace - Google Patents

Description

  The present invention relates to a melting furnace.

Conventionally, a melting furnace using coal coke as a fuel has been used as a melting furnace for melting iron (see Patent Document 1).
In the melting furnace described in Patent Document 1, the raw material to be melted and coal coke are alternately charged in a cylindrical shaft furnace, and the coal coke is burned with air fed from the tuyere into the furnace, so that the atmosphere has a high temperature ( The over-tropics reaching 600 ° C. or higher were formed, and the raw materials to be dissolved were dissolved.

However, the melting furnace described in Patent Document 1 has a disadvantage that the amount of CO ₂ emission is large, the amount of dust generation and the amount of sulfur oxide (SO _X ) emission is also large, and the cost for environmental measures is high.

  In recent years, global environmental problems have become even more serious, and in anticipation of greenhouse gas reduction and anticipated depletion of fossil fuels, securing energy resources and developing clean and renewable energy Is an urgent need. Therefore, the use of biomass solid fuel (bio-coke) as an alternative fuel for coal coke is attracting attention (see Patent Document 2).

JP 2005-90792 A Japanese Patent No. 4088933

  However, it has been considered that conventional melting furnaces are difficult to use biomass solid fuel. The reason for this is that, as shown in FIG. 4, the biomass solid fuel has a fracture strength higher than that of coal coke at room temperature, but after carbonization at a high temperature, it is brittle and has no strength, so it is compressed from above. There is a risk of collapse (crushing) due to the load. Furthermore, when biomass solid fuel (bio-coke) is introduced into the top of a conventional melting furnace, the biomass solid fuel is gasified in the pretropical zone with high-temperature furnace top gas. Alternatively, it may be oxidized and burned to be ash and decomposed or crushed. That is, the biomass solid fuel does not work effectively for combustion in the supertropics in the furnace, and therefore it is very difficult to apply the biomass solid fuel to the melting furnace.

  Accordingly, an object of the present invention is to provide a melting furnace that enables effective use of biomass solid fuel and that melts a material to be melted stably and efficiently.

A melting furnace according to the present invention includes a vertical cylindrical furnace main body that burns coal coke accumulated therein, and burns biomass solid fuel at a height position of a side wall portion corresponding to the hypertropy of the main furnace body. A plurality of biomass combustion devices for supplying biomass combustion heat are disposed, and the biomass combustion device has a blow outlet at the tip portion and a cylindrical burner for storing biomass solid fuel from the longitudinal intermediate portion to the tip portion A hot air supply pipe for supplying heated combustion air for heating the biomass solid fuel in the cylindrical burner body and continuing combustion, the vicinity of the tip of the intermediate portion of the cylindrical burner body Are connected in communication .

Also, the biomass solid fuel is made of a short cylindrical shape or a circular plate-like bio-coke bound by heating to a predetermined temperature with high hardness while compressing the biomass material-derived plants with high pressure.
Moreover, the said biomass combustion apparatus makes the said cylindrical burner main body into an inward downward inclination with a predetermined inclination angle, and the inclination angle is set to 25 degrees-60 degrees.
The arrangement height position of the biomass combustion apparatus is substantially the same as the arrangement height position of the tuyere or above the arrangement height position of the tuyere.

  According to the melting furnace of the present invention, biomass combustion heat can be supplied directly to the supertropical height position of the furnace body while holding the biomass solid fuel without applying an excessive compressive load. Stable operation can be achieved by effectively using the raw material to be dissolved, and the amount of coal coke introduced from above can be reduced. That is, the consumption of coal coke can be reduced to reduce fuel costs, and the generation of greenhouse gases can be suppressed by the carbon neutral properties of biomass solid fuel.

It is the section front view showing one embodiment of the present invention. It is a principal part expanded sectional front view. It is the graph which showed the temperature distribution in a furnace main body, a horizontal axis is temperature, and a vertical axis | shaft is a division of the height direction in a furnace main body. It is a graph which shows the compressive strength of coal coke and biomass solid fuel, a horizontal axis is temperature, and the vertical axis | shaft has shown the compressive strength with respect to a load.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.
As shown in FIG. 1, the melting furnace of the present invention includes a vertical cylindrical furnace body 1 for burning coal coke C deposited therein, and the height of the side wall 5 corresponding to the supertropical region 11 of the furnace body 1. A plurality of biomass combustion apparatuses 3 and 3 for burning biomass solid fuel B and supplying biomass combustion heat are disposed at the position.

  The furnace body 1 includes a cylindrical side wall portion 5 having a plurality of tuyere 6 and 6 for supplying combustion air, a ceiling wall portion 7 having an upper opening-shaped inlet 14, and a cylindrical side wall portion 5. And a furnace bottom portion 8 having a gradually downwardly inclined hearth 16 toward a hot water outlet 15 for discharging the raw material A to be melted. In the furnace body 1, a coke bed deposition layer 2 stacked on the hearth 16 and stripes laid above the coke bed deposition layer 2 and alternately layered with the raw material A layer and the coal coke C layer are stacked. A laminated layer 9 is laminated. In the coke bed deposition layer 2 and the striped deposition layer 9, the coal coke C forms a gap through which combustion gas or air passes. Further, the furnace body 1 has a side opening-like exhaust gas discharge port 17 near the boundary between the side wall portion 5 and the ceiling wall portion 7. Each tuyere 6 is connected to a blower (not shown), and is supplied with air sent from the blower. In addition, between the blower and the tuyere 6, for example, a combustion chamber for burning exhaust gas, and a heat exchanger for exchanging normal temperature air to high temperature air by the heat of the high temperature exhaust gas from the combustion chamber, It is also preferable to comprise.

  In FIG. 1 and FIG. 3, when the inside of the furnace body 1 is divided according to the heat state of the raw material A to be dissolved, the striped deposition layer 9 in which the raw material A and the coal coke C are alternately stacked In the upper part, a pre-tropical zone 13 in which the raw material A to be dissolved is preheated is formed. Is forming. Further, in the coke bed deposition layer 2, a supertropical region 11 where the material A to be melted is overheated is formed above the height position of the tuyere 6 to which combustion air is supplied. Below the position, a hot water pool 10 is formed in which the melted raw material A is accumulated. As shown in the graph of FIG. 3, the temperature in the furnace body 1 gradually rises to about 500 ° C. to 1300 ° C. in the pretropical zone 13 and gradually rises to 1400 ° C. to 1600 ° C. in the melting zone 12. However, after reaching a high temperature peak P of 1600 ° C. to 1800 ° C. in the supertropical zone 11, the distribution decreases to 500 ° C. or less in the pool 10.

As shown in FIG. 2, the biomass combustion apparatus 3 includes a cylindrical burner main body 31 that has the blowout port 30 at the tip end portion 3A and accommodates the biomass solid fuel B from the longitudinal intermediate portion 3C to the tip end portion 3A. The hot air supply pipe 4 for supplying heated combustion air H for heating the biomass solid fuel B in the cylindrical burner main body 31 and continuing combustion is communicated with the vicinity of the tip 3A of the intermediate portion 3C of the cylindrical burner main body 31. It is connected.
The biomass combustion apparatus 3 is attached to a mounting cylinder portion 1 </ b> A that protrudes from the side wall portion 5 of the furnace body 1 so as to be inclined upward and outward. 3 A of front-end | tip parts of the biomass combustion apparatus 3 consist of a cylindrical refractory material of short thickness, and are hold | maintaining so that the biomass solid fuel B inside the cylindrical burner main body 31 may not be crushed. The biomass combustion apparatus 3 injects the blowing hot air F from the blower outlet 30 of the tip 3A, and the blower outlet 30 is directed in the center direction (inward) of the furnace body 1 and is inclined slightly downward. It is installed.

  The hot-air supply pipe 4 has a heater 32 and heats air supplied from a blower (not shown) to 300 ° C. to 700 ° C. to form heated combustion air H for ignition and combustion continuation in the cylindrical burner main body 31. It is configured to be able to supply. If the temperature of the heated combustion air H supplied from the hot air supply pipe 4 is less than 300 ° C, the biomass solid fuel B may not be ignited, and is preferably set to 450 ° C to 600 ° C.

In the biomass combustion apparatus 3, a fuel input cylinder portion 33 for supplying the biomass solid fuel B to the base end portion 3 </ b> B side of the hot air supply pipe 4 is connected in communication. The fuel charging cylinder portion 33 has a first charging valve 21 and a second charging valve 22. The first charging valve 21 and the second charging valve 22 are set to open and close alternately, and the biomass burner body 31 is intermittently supplied with the biomass solid fuel B while preventing the backflow of hot air in the cylindrical burner body 31. It is configured to be sent in.
Further, the biomass combustion apparatus 3 pushes the biomass solid fuel B replenished from the fuel input cylinder portion 33 of the base end portion 3B toward the tip portion 3A side, and whether or not a predetermined amount of the biomass solid fuel B remains in the intermediate portion 3C. It has pushing means 34 for detecting this.

  A lid member 38 that holds the biomass solid fuel B in the cylindrical burner body 31 is attached to the outlet 30 of the biomass combustion apparatus 3. The lid member 38 has a lattice-like window portion through which the blown hot air F ejected from the blower outlet 30 passes. The eyes of the grid-like window part have a vertical and horizontal interval dimension set to 30 mm or less. If the vertical and horizontal distance between the grid windows exceeds 30 mm, the amount of biomass solid fuel B discharged from the outlet 30 without sufficient combustion increases, and the combustion efficiency of the biomass combustion apparatus 3 may be reduced. There is.

The biomass solid fuel B is composed of biocoke having a short cylindrical shape or a circular disc shape in which a plant-derived biomass raw material is compressed at a high pressure and heated to a predetermined temperature and bonded to a high hardness.
As a raw material of the biomass solid fuel B, for example, wood chips, beverage residue, tofu okara, shochu residue, cow dung, chicken dung, pig dung, and biomass waste (RPF, RDF) can be used. Biomass solid fuel B has high hardness by changing the chemical bond of cellulose, hemicellulose, and lignin, which are the main components, by putting these raw materials in a cylindrical mold and heating them to a predetermined temperature while compressing them at high pressure. It is made into the short cylinder-shaped solid fuel (bio-coke). The biomass solid fuel B is not carbonized. The biomass solid fuel B has a diameter set to 20 mm to 120 mm and a length dimension set to 30 mm to 200 mm. It is preferable that the biomass solid fuel B has a circular disk shape in which the diameter of the biomass solid fuel B is set to 80 mm to 120 mm and the length dimension is set to 30 mm to 50 mm. A cylinder whose diameter is set to 20 mm or more and smaller than 80 mm and whose length dimension is set to be larger than 50 mm and 200 mm or less is a short cylindrical shape (log shape), and the biomass solid fuel B has a short cylindrical shape. Be good.

The biomass solid fuel B has a carbon neutral property that does not increase the CO ₂ emission amount because the same amount of CO ₂ generated by combustion is absorbed by photosynthesis. In addition, since it contains almost no sulfur, it does not emit sulfur oxides (SO _x ) and is an environmentally friendly fuel. The biomass solid fuel B is represented by the chemical formula C _n H _m O _p and has a calorific value comparable to that of fossil fuels that emit a large amount of CO ₂ such as coal and petroleum. The biomass solid fuel B is heated only from room temperature to 200 ° C., and no exothermic reaction occurs. From about 200 ° C. to about 600 ° C., heat is generated while generating CO, CO ₂ and H ₂ by gasification by thermal decomposition. Biomass solid fuel B can react with a solid surface and burn at a high temperature of 600 ° C. or higher to obtain a large amount of heat. That is, the biomass solid fuel B exhibits its true value as an alternative fuel for fossil fuels in an atmosphere of 600 ° C. or higher.

In the biomass combustion apparatus 3, the cylindrical burner body 31 is inclined inward and downward with a predetermined inclination angle θ, and the inclination angle θ is set to 25 ° to 60 °.
If the inclination angle θ of the cylindrical burner main body 31 is less than 25 °, the biomass solid fuel B may not be smoothly fed and may be clogged in the middle. There is a possibility that the solid fuel B is excessively compressed and collapsed (collapsed). More preferably, the angle is set to 35 ° to 40 °. Incidentally, At a present invention, the "inclination angle θ" is intended to refer to the horizontal L _0, the angle at which the axis line L ₁ of the cylindrical burner body 31 is formed (see FIG. 1).

The arrangement height position of the biomass combustion apparatus 3 is substantially the same as the arrangement height position of the tuyere 6 or is higher than the arrangement height position of the tuyere 6.
In the interior of the furnace body 1, the supertropical region 11 is formed at an upper position including the height position of the tuyere 6, and the biomass combustion apparatus 3 is directly connected to the supertropical region 11 in the furnace body 1. It is arranged to supply biomass combustion heat. It is desirable that the biomass combustion device 3 and the tuyere 6 are alternately shifted in the circumferential direction of the furnace body 1.

The use method (action) of the melting furnace of the present invention described above will be described.
As shown in FIG. 1 and FIG. 2, biomass solid fuel B is burned inside the biomass combustion apparatus 3 to generate biomass combustion heat, supplied to the furnace body 1 as blown hot air F, and introduced from the inlet 14. The coal coke C on the formed coke bed deposition layer 2 is heated and burned to form the supertropical region 11.

  In the biomass combustion apparatus 3, the biomass solid fuel B is ignited by the high-temperature (300 ° C. to 700 ° C.) heated combustion air H from the hot air supply pipe 4 and combusts while being gasified. After the combustion by gasification, the biomass solid fuel B starts to disintegrate while being char-combusted, and the biomass solid fuel B becomes fine small pieces and is blown out into the furnace body 1 by the pressure of the heated combustion air H. Together with this, a small piece of biomass solid fuel B is blown into the furnace body 1. By supplying biomass combustion heat generated by burning the biomass solid fuel B in the biomass combustion apparatus 3 into the supertropical region 11 of the furnace body 1 and blowing the small piece of biomass solid fuel B, Small pieces of biomass solid fuel B are burned in the voids of coal coke C, and a large amount of heat is generated (compared to the case of simply burning coal coke C). In other words, the melting furnace of the present invention can reduce the consumption of coal coke C by utilizing the amount of heat of the biomass solid fuel B burned in the biomass combustion apparatus 3.

  Since the biomass combustion apparatus 3 is inclined inward with a predetermined inclination angle θ, the biomass solid fuel B to be replenished later rolls around with its own weight and is sequentially sent to the tip portion 3A side. Alternatively, the biomass solid fuel B may be pushed into the tip portion 3A side by the pushing means 34 and sequentially conveyed. The biomass solid fuel B is disintegrated and consumed as it is burned. When the pushing means 34 detects that a predetermined amount of the biomass solid fuel B is not stored in the intermediate portion 3C of the biomass combustion apparatus 3, the fuel is charged. Since the biomass solid fuel B is replenished from the cylindrical portion 33 and (automatically) conveyed to the outlet 30 side of the tip 3A, the biomass solid fuel B combusted by the heated combustion air H from the hot air supply pipe 4 Is maintained at an appropriate amount.

  Note that the design of the present invention can be changed. For example, the biomass combustion apparatus 3 may be provided with the fuel injection cylinder portion 33 closer to the distal end portion 3A than the hot air supply pipe 4 (not shown).

  As described above, the melting furnace according to the present invention includes the vertical cylindrical furnace main body 1 for burning the coal coke C accumulated therein, and the height position of the side wall portion 5 corresponding to the supertropical region 11 of the furnace main body 1. In addition, since a plurality of biomass combustion apparatuses 3 and 3 for burning the biomass solid fuel B and supplying biomass combustion heat are disposed, the biomass solid fuel B is held without applying an excessive compressive load. Combustion can be performed at the height of the supertropical area 11, and the biomass combustion heat can be effectively utilized for melting the raw material A to be dissolved, so that stable operation can be performed, and the amount of coal coke C introduced from above can be reduced. That is, while reducing the consumption of coal coke C and reducing the fuel cost, it is possible to suppress the generation of greenhouse gases by the carbon neutral property of the biomass solid fuel B. In other words, the biomass solid fuel B, which has conventionally been considered impossible to be applied to a melting furnace, can be effectively used as an alternative fuel for coal coke C in the melting furnace if the present invention is used.

  Further, the biomass combustion apparatus 3 includes a cylindrical burner main body 31 that has a blowout port 30 at the front end portion 3A and accommodates the biomass solid fuel B from the longitudinal intermediate portion 3C to the front end portion 3A. Since the hot air supply pipe 4 for supplying the heated combustion air H for heating the biomass solid fuel B inside and continuing the combustion is connected in communication with the vicinity of the tip 3A of the intermediate part 3C of the cylindrical burner body 31. The biomass solid fuel B can be reliably burned by heating at an appropriate temperature, the biomass solid fuel B can be continuously burned in the biomass combustion apparatus 3, and the blown hot air injected from the outlet 30 F can be stably maintained at a high temperature. In particular, if the temperature of the heated combustion air H is set to 450 ° C. to 600 ° C., the biomass solid fuel B can be reliably ignited and the biomass combustion heat can be effectively utilized.

In addition, the biomass solid fuel B is composed of biocoke having a short cylindrical shape or a circular disk shape obtained by compressing a plant-derived biomass raw material at a high pressure and heating it to a predetermined temperature so as to be combined with high hardness. The calorific value comparable to fossil fuels that emit a large amount of CO ₂ , etc., can be secured, and it is carbon neutral, so it does not increase CO ₂ emissions and contains almost no sulfur. There is no emission of substances (SO _x ), and it can contribute to the preservation of the global environment as an alternative fuel for fossil fuel.

  Moreover, since the biomass burner 3 makes the cylindrical burner main body 31 inward and downward inclined with a predetermined inclination angle θ and the inclination angle θ is set to 25 ° to 60 °, the biomass solid fuel B The biomass solid fuel B can be sent smoothly without being disintegrated by applying an excessive compressive load.

  Moreover, since the arrangement | positioning height position of the biomass combustion apparatus 3 is substantially the same as the arrangement | positioning height position of the tuyere 6, or is higher than the arrangement | positioning height position of the tuyere 6, biomass combustion heat is The furnace body 1 can be reliably supplied at a height position corresponding to the supertropical zone 11.

DESCRIPTION OF SYMBOLS 1 Furnace main body 3 Biomass combustion apparatus 3A Tip part 3C Middle part 4 Hot air supply pipe 5 Side wall part 6 Tuyere 11 Super tropical 30 Outlet 31 Cylindrical burner main body B Biomass solid fuel C Coal coke θ Inclination angle H Heating combustion air

Claims (4)

A vertical cylindrical furnace main body (1) for burning coal coke (C) deposited therein is provided, and at the height position of the side wall (5) corresponding to the supertropical region (11) of the furnace main body (1), A plurality of biomass combustion apparatuses (3) and (3) for supplying biomass combustion heat by burning biomass solid fuel (B) ,
The biomass combustion apparatus (3) has a blower outlet (30) at the tip end portion (3A) and a cylinder for storing the biomass solid fuel (B) from the longitudinal intermediate portion (3C) to the tip end portion (3A). A hot air supply pipe (4) for supplying heated combustion air (H) for continuing combustion by heating the biomass solid fuel (B) in the cylindrical burner body (31). ) Is connected in communication with the vicinity of the tip (3A) of the intermediate part (3C) of the cylindrical burner body (31) . 2. The dissolution according to claim 1, wherein the biomass solid fuel (B) comprises a biocoke having a short cylindrical shape or a circular disc shape obtained by compressing a plant-derived biomass raw material at a high pressure and heating the biomass raw material to a predetermined temperature and bonding it to a high hardness. Furnace. In the biomass combustion apparatus (3), the cylindrical burner body (31) is inclined inwardly with a predetermined inclination angle (θ), and the inclination angle (θ) is set to 25 ° to 60 °. melting furnace according to claim 1 or 2, wherein there. The arrangement height position of the biomass combustion device (3) is substantially the same as the arrangement height position of the tuyere (6) or above the arrangement height position of the tuyere (6). The melting furnace according to 1, 2 or 3.

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