JP3420623B2 - Desulfurization firing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to pellets prepared by mixing and molding minerals or various inorganic substances containing a component that reacts with sulfur such as agglomerated limestone, dolomite and magnesite, and various inorganic substances. It is used in the technical field of obtaining a product by firing an agglomerate raw material such as pellets, which is produced by mixing and molding an organic substance with an organic substance, and particularly relates to a desulfurization firing apparatus thereof.

[0002]

2. Description of the Related Art In order to bake the above raw materials at a high temperature, a cylindrical rotary furnace which is gently rotated around an axis slightly inclined with respect to a horizontal plane is widely used. The agglomerate raw material is supplied from one end on the upper side of the cylindrical rotary furnace,
It moves toward the other end on the lower side while receiving the rotation of the rotary furnace.

On the other hand, the combustion flame and combustion gas of liquid fuel or pulverized coal are supplied from the other end of the rotary furnace so as to flow countercurrently to the moving direction of the raw material, and the raw material is heated during the movement. It is baked, dropped from the other end of the rotary furnace, and sent to the cooling device.

[0004]

In the above cylindrical rotary furnace, the combustion gas comes into contact only with the layer surface of the raw material in the rotary furnace, so that the rate of heat energy transfer between the raw material and the combustion gas is not large, Since the combustion gas is discharged from one end on the feed side of the raw material at a high temperature without sufficient heat exchange, a large amount of heat energy is lost. Therefore, a large amount of fuel is required per unit amount of product.

A so-called preheating device has been conventionally used to recover a large amount of heat energy held by the high temperature combustion gas. This preheating device forms, for example, an agglomerated raw material as a deposited layer, slowly moves it, and causes the high-temperature combustion gas discharged from the rotary furnace to flow through the voids of the deposited layer to feed the raw material to the rotary furnace. By preheating before the firing in step 1, the retained thermal energy of the high temperature combustion gas is recovered. By installing the preheating device, the required fuel amount per product unit is significantly reduced, and the energy saving effect becomes great.

[0006] When burning a fuel rich in sulfur in a rotary furnace without a preheating device to burn limestone or dolomite, for example, the contact between the combustion gas flow and the agglomerate layer is insufficient. SO _{x in} combustion gas is hardly absorbed by limestone and dolomite. However, when the preheating device is attached to the rotary furnace, since the high temperature combustion gas flows through the deposition layer of the raw material agglomerates in the preheating device, the surface area of contact between the combustion gas and the agglomerates is large. In addition, there is a temperature zone suitable for absorbing SO _x in the agglomerated layer. Therefore, a considerable proportion of SO _{x in} the combustion gas is contained in the raw material agglomerates.
It is absorbed by reacting with CaO and MgO . That is, since the raw material agglomerates containing the sulfur content in the preheating device are fired in the rotary furnace, the sulfur content is considerably large in the fired product. As a result, it is necessary to use liquid or gas fuel that does not contain sulfur for products that do not like sulfur, which causes a problem of high fuel cost.

The present invention solves such a problem, and when a rotary furnace and a preheating device are used together, even if a fuel such as heavy oil or pulverized coal containing sulfur is used, the product has a very low sulfur compound content. It is an object to provide an apparatus for obtaining a baked product.

[0008]

According to the present invention, the above object is to provide a preheating device provided with a hearth for receiving a raw material in the form of agglomerates supplied from the outside to form a deposition layer, and communicating with the preheating device. And a rotary furnace that receives the raw materials sequentially falling from the hearth and moves the raw materials to the discharge portion while rotating, and the heating gas that feeds the heating gas into the rotary furnace at the discharge portion of the rotary furnace. In a calcining device that is provided with an inlet pipe and in which the heating gas flows from the rotary furnace to the preheating device countercurrent to the flow of the raw material and then flows through the deposition layer, the preheating device has a hearth.
Is formed as a horizontal surface that rotates about a vertical line, and in the space from the space of the rotary furnace until space in the preheating device
This is achieved by providing a powder feeding pipe for spraying desulfurized fine powder from the outside at an arbitrary position below the hearth .

[0009]

[0010]

In the present invention having such a structure, the fine powder of the raw material containing the component that reacts with the sulfur content is spray-supplied from the powder feeding pipe into the combustion gas. The fine powder is dispersed in the combustion gas and reacts with the above-mentioned sulfur in a short time, for example, when the fine powder is finely powdered limestone, a finely powdered sulfur compound is produced. Thus, SOx in the combustion gas reacts with the fine powder and is chemically absorbed by the fine powder until the high-temperature combustion gas reaches the deposition layer in the preheating device from the space in the rotary furnace. It Most of the fine powder containing the sulfur compound flows along with the flow of the combustion gas, flows through the voids of the deposition layer in the preheating device, and is discharged from the preheating device.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view of a first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a rotary furnace composed of a rotating body having a horizontal tubular shape, and its axis 2 is inclined at a slight angle θ with respect to a horizontal plane, and the axis 2 is made by a bearing device (not shown). It is rotatably supported around and is rotationally driven by a drive device (not shown). The rotary furnace 1 has openings 1A and 1B at both ends in the direction of the axis 2, and a fuel supply pipe 3 for supplying a fluid or fine powder fuel is arranged in the opening 1B on the lower end side (the left end side in the figure). It is set up. Further, an air supply pipe 4 for supplying combustion air is provided in proximity to the fuel supply pipe 3, and the fuel is supplied through the opening 1
It burns in a space close to B and generates high-temperature combustion gas. It should be noted that instead of the fuel supply pipe 3 and the air supply pipe 4, a heating gas supply pipe for supplying combustion gas that has already burned may be provided.

A seal 5 for allowing relative rotation with respect to the rotary furnace 1 is provided in the opening 1B as a discharge portion on the lower end side of the rotary furnace 1.
A product discharge pipe 5 having A and extending downward so as to close the opening 1B is provided.

A preheating device 6 is arranged above the upper end of the rotary furnace 1.

The preheating device 6 includes an annular plate-shaped hearth 8 that rotates in a horizontal plane about a vertical axis 7 and an auxiliary fuel supply pipe 9 that is fixedly disposed above the hearth 8 and faces downward. A furnace lid 10 having an air supply pipe 9A, and a peripheral wall 1 having a seal 11 at the outer peripheral portion of the hearth 8 for allowing the hearth 8 to rotate.
2, and a raw material deposit layer 13 is formed in an annular space surrounded by the hearth 8, the peripheral wall 12 and the outer peripheral portion of the furnace lid 10. The fuel from the auxiliary fuel supply pipe 9 can assist the preheating in the preheating device 6.
The auxiliary fuel supply pipe is not essential in the present invention.

A raw material storage tank (not shown) is provided above the preheating device 6 and serves as a raw material to be fired.
An agglomerate containing a component that reacts with the sulfur content is stored inside. A supply pipe 14 extends downward from the raw material storage tank, and its lower end faces the furnace lid 10 so as to supply the raw material onto the hearth 8 and form the deposited layer 13.

A rod-shaped pusher 1 which passes through the peripheral wall 12 in the radial direction and reciprocates in the longitudinal direction as needed.
5 are appropriately provided at a plurality of positions in the circumferential direction.

Further, exhaust pipes 16 having valves (not shown) are connected to the outer peripheral portion of the furnace lid 10 at a plurality of circumferential positions.

The hearth 8 of the preheating device 6 is open at the center and extends downward in a tapered shape to form a guide portion 8A. Below the guide portion 8A, it falls from the hearth 8.
In order to supply the raw material to the rotary furnace 1, a chute tube 18 extending obliquely downward is provided via a seal 17 that allows relative rotation with the guide portion 8A. The shoot tube 18
The lower end 18A of the rotary furnace 1 faces the opening 1A on the upper end side of the rotary furnace 1. Further, on the side of the opening 1A of the rotary furnace 1, a cylindrical hollow tower body 19 having a seal 19A for allowing relative rotation with the rotary furnace 1 extends upward, and the upper part thereof is
The empty tube body 19 is connected to the upper side portion of the chute tube 18 and
Forms a communication space between the rotary furnace 1 and the preheating device 6 .

Further, in the opening 1A on the upper end side of the rotary furnace 1, a fine powder containing a component which penetrates the hollow tower body 19 and reacts with a sulfur content, for example, a fine powder of a raw material to be fired. A powder feeding tube 20 for supplying the powder is provided.

In the apparatus of this embodiment having such a structure, the granular material as a raw material is fired in the following manner.

First, the above-mentioned agglomerates as raw materials are dropped and supplied from the raw material storage tank through the supply pipe 14 onto the hearth 8 of the preheating device 6. Since the hearth 8 rotates slowly about the axis, the agglomerates form a uniform deposit layer 13 in the circumferential direction. Since the space on the hearth 8 where the deposit layer 13 is formed is opened inwardly of the radius, the deposit layer 13 forms a slope facing the space with a repose angle as shown in FIG. Become.

The space on the hearth 8 is filled with the combustion gas generated in the auxiliary fuel supply pipe 9 and the combustion gas from the rotary furnace 1. The agglomerates on the hearth 8 are the combustion gas. Is preheated by convective heat transfer when passing through the voids between the agglomerates and reaching the exhaust pipe 16 and radiant heat transfer on the slope, and is primarily fired. Then, as the pusher 15 reciprocates,
The above-mentioned primary calcinated agglomerates fall from the slope side.

The dropped agglomerates are guided by the chute tube 18 and reach the rotary furnace 1. Since the axis 2 of the rotary furnace 1 is inclined with respect to the horizontal plane and is slowly rotating around the axis 2, the agglomerates are rolled and directed from the upper end side to the lower end side (in the figure, Move to the left). In the rotary furnace 1, the combustion gas generated in the fuel supply pipe 3 flows from the lower end side to the upper end side so as to flow countercurrently to the moving direction of the agglomerates, and has already been preheated by the preheating device 6. The above-mentioned agglomerates that have been received are sufficiently fired in the rotary furnace 1. The fired agglomerates successively fall from the lower end side opening 1B of the rotary furnace 1 to the product discharge pipe 5, where they are cooled and taken out as a product.

After burning the agglomerates in the rotary furnace 1, the combustion gas comes into contact with the fine powder spray-supplied from the powder-sending powder 20 arranged at the upper end opening of the rotary furnace 1. The combustion gas produced by using heavy oil, pulverized coal, etc. as a fuel contains a sulfur content, and a fine powder (a fine powder of a raw material may be used) containing a component that reacts with the sulfur content and supplied by spraying, for example, a raw material Is limestone, the finely divided limestone is the sulfur content (SO
reacts with x) to produce a finely divided compound. That is, the sulfur content in the combustion gas is absorbed by the compound in the form of fine powder.

The combustion gas rises in the inner space of the empty column body 19 and reaches the inner space of the preheating device 6. The finely powdered compound also rides on the flow of the combustion gas and the preheating device 6
Reach Combustion gas with such compounds is still in a high temperature state, and together with the combustion gas generated in the preheating device, the deposited layer 1 of the raw material formed on the hearth 8 of the preheating device 6.
After passing through the void 3 and preheating the raw material of the deposited layer 13 there, the material is exhausted through the exhaust pipe 16 in a state of being cooled. At that time, the fine powdery compound is sufficiently small with respect to the voids formed in the raw material agglomerate, and penetrates through the voids and is discharged together with the combustion gas. Thus, in the present embodiment, before the combustion gas preheats the deposited layer in the preheating device 6, the sulfur content in the combustion gas is combined as fine powder, and when flowing through the deposited layer. Exhausted without reacting with raw materials.

In the present embodiment, the position of the powder feeding tube for feeding the fine powder is not necessarily limited to the cylindrical rotary furnace 1,
For example but it may also at any position in the superficial body 19 as Okukonakan 20A of FIG. And in this case, the powder transfer tubes 20A, 2
The shape, size, and number of 0B are arbitrary.

The empty column body 19 connecting the cylindrical rotary furnace 1 and the preheating device 6 is not necessarily limited to the one having the structure as shown in FIG. 1, and is, for example, the reference numeral 21 in FIG. 2 as the second embodiment. As shown in the drawing, the structure in which the drop supply of the granular material as the raw material and the circulation of the high temperature combustion gas are performed in the same space may be used. In FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted (the same applies to FIG. 3 described later).

Further, the preheating device 6 is not necessarily limited to the one shown in FIG. 1 as long as the high temperature combustion gas exchanges thermal energy by flowing through the deposition layer of the agglomerate raw material. The format and shape are arbitrary. Further, the auxiliary fuel supply pipe 9 and the air supply pipe 9A for feeding the combustion air in FIG. 1 may not be installed.

In the case of a preheating device having a hearth rotating in the horizontal plane around the vertical axis, the preheating device is not necessarily limited to the one shown in FIG. 1, but the hearth is composed of upper and lower two stages as shown in FIG. 3, for example. Even if it does. In the drawing, reference numeral 22 is another hearth, and another annular grain agglomerate deposition layer 23 is formed above the grain agglomerate deposit layer 13 on the hearth 8 as in FIG. Further, reference numeral 24 is an exhaust pipe for diverting a part of the combustion gas to the outside of the device.

In the present invention, the fine powder is not particularly limited as long as it contains a component that reacts with the sulfur content in the combustion gas, but it is easiest to use the fine powder as the raw material. For example, if the raw material to be fired is one of limestone, dolomite, magnesite, etc., the fine powder can be any one of these, but it would be easier to make it identical to the raw material .

[0033]

As described above, according to the present invention, when the agglomerated raw material is fired at a high temperature, even if a fluid having a high sulfur content and a fine powder fuel are used, a fired product having a very low sulfur compound content is obtained. The effect of being able to obtain continuously with a small fuel consumption rate is obtained. Further, according to the present invention, there is an advantage that it can be carried out by a simple device and only a powder feeding pipe is added to the conventional baking device.

[Brief description of drawings]

FIG. 1 is a sectional view taken along a plane including an axis, showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a second embodiment device in a plane including an axis.

FIG. 3 is a cross-sectional view showing a third embodiment device in a plane including an axis.

[Explanation of symbols]

1 rotary furnace 3 Heating gas inlet pipe 6 Preheating device 8 hearth 13 sedimentary layers 20, 20A, 20B powder transfer tube

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Claims (4)

(57) [Claims] 1. A preheating device including a hearth that receives a granular material supplied from the outside to form a deposited layer, and a raw material that is in communication with the preheating device and that sequentially drops from the hearth and rotates. While having a rotary furnace for moving the raw material to the discharge part, the discharge part of the rotary furnace is provided with a heating gas feed pipe for feeding the heating gas into the rotary furnace, and the heating gas is rotated. in the sintering apparatus flowing through the deposition layer after flowing countercurrent to the flow of material toward the preheater from the furnace, the preheating device
The hearth is formed as a horizontal plane that rotates about a vertical line.
It is, at any position below the empty <br/> between the a and the hearth from the space of the rotary furnace until space in the preheater, and pollinators tube for spraying desulfurization fine powder externally provided A desulfurization and firing device characterized in that 2. The desulfurization and firing device according to claim 1, wherein the powder feeding pipe is provided so as to face the flow of the heating gas. Wherein Okukonakan is, desulfurization baking apparatus according to claim 1, characterized in that it has been kicked set in the communication space of the preheating device and the rotary furnace. 4. A rotary furnace is formed as a rotary member to rotate the axis slightly inclined cell line with respect to the horizontal line or horizontal line, claims Okukonakan is to what is kicked set in the inner space of the rotary body The desulfurization firing apparatus according to claim 1 or 2.