JP2010243145A - Device and method of cooling rotary kiln - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of cooling a rotary kiln capable of correctly measuring a temperature distribution of a kiln shell 5 by an infrared ray thermometer or a radiation thermometer even during cooling, and properly cooling an outer surface. <P>SOLUTION: In this method of cooling the rotary kiln provided with a refractory on its inner face, and heating a treated object by burning a fuel by a burner disposed at its one end side, mist is sprayed to the cooling air distributed toward the outer surface vertically at a lower part with respect to a rotating shaft of the rotary kiln. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to cooling the outer surface of a rotary kiln.

  Conventionally, Patent Document 1 discloses a technique for cooling a rotary kiln by spraying mist. In this patent document 1, the nozzle part which mixes pressure water and pressure air is provided, mist is sprayed on the kiln shell surface, and the kiln shell is cooled by the evaporation heat of the water which collided with the kiln shell surface. The sprayed mist is such that the kiln shell surface does not get wet, and the entire amount of water vaporizes and evaporates on the kiln shell surface. By using this technique, since a water film is not formed on the kiln shell surface, the kiln surface temperature can be measured with an infrared thermometer.

JP 2001-241851 A

However, Patent Document 1 has a problem that the entire rotary kiln cannot be appropriately cooled because the cooling effect is concentrated on the portion where the mist is sprayed.
The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a rotary kiln cooling device capable of appropriately cooling the outer surface of the rotary kiln.

  In order to solve the above-described object, in the present invention, a refractory material is provided on the inner surface, a fuel is burned by a burner provided on one end side, and the object to be processed is heated in a rotary kiln cooling method. The mist was sprayed on the cooling air blown toward the outer surface vertically below.

  Therefore, the outer surface of the rotary kiln can be appropriately cooled.

It is a side view in the rotary kiln 1 of this invention. 1 is a radial cross-sectional view of a rotary kiln 1 in a first embodiment. 2 is a perspective view of a cooling fan 2. FIG. FIG. 3 is a view showing a temperature distribution in the rotary kiln 1. FIG. 3 is a radial cross-sectional view of a rotary kiln 1 in a second embodiment. It is a figure which shows the cooling position of the cooling fan 2 in Embodiment 2. FIG. 6 is a side view of a rotary kiln 1 according to Embodiment 3. FIG. FIG. 6 is a radial cross-sectional view of a rotary kiln 1 in a fourth embodiment. 10 is a side view according to Embodiment 4. FIG. It is a comparative example of the present invention.

[Embodiment 1]
[Outline of rotary kiln]
An outline of the rotary kiln 1 will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view of the rotary kiln 1, and FIG. 2 is a radial sectional view. In addition, let the rotating shaft direction (longitudinal direction) of the rotary kiln 1 be a y-axis, and let the burner 30 side be a y-axis negative direction. Further, a vertically upward direction is defined as a positive z-axis direction, and a radial axis perpendicular to the y-axis and the z-axis is defined as an x-axis. The x-axis positive direction is the right side of FIG.

  The rotary kiln 1 has a cylindrical kiln shell 5, and a refractory brick 12 is provided on the inner peripheral side. The rotary kiln 1 rotates in the clockwise direction in FIG. 2, but may be counterclockwise. The raw material 9 is introduced into the inner peripheral side of the refractory brick 12 and fired by the heat of the burner 30. Further, a cooling fan 2 is provided on the negative direction side of the z-axis with respect to the rotation axis L of the rotary kiln 1, and the kiln shell 5 is cooled by air blown from the cooling fan 2.

  The cooling air 7 is blown from the cooling fan 2 toward the positive z-axis direction. For this reason, the cooling air 7 hits the kiln shell 5 from the portion of the circumference that is closest to the z-axis negative direction. The cooling fan 2 uses an axial fan, but may be another type of fan. Further, the cooling air 7 from the cooling fan 2 may be blown toward the outer surface of the kiln shell 5 of the rotary kiln 1 that is vertically below the rotation axis L (on the negative side of the z-axis). There is no particular limitation.

  A plurality of cooling fans 2 are provided in a row parallel to or substantially parallel to the y-axis. There may be two or more rows depending on the cooling range and the required capacity (see Embodiment 4 and later). The intervals between the cooling fans 2 are provided at equal intervals of 1.5 to 3.0 m, and the blowing direction is on the z-axis positive direction side. The distance between the air outlet of the cooling fan 2 and the kiln shell 5 is in the range of 0.6 to 3 m (the reason will be described later).

  Cooling air 7 including mist 4 is output from cooling fan 2, and cooling air 7 including mist 4 is at least one place within a predetermined range from the kiln end on the burner 30 attachment side toward the y-axis positive direction. It shall be installed. In the first embodiment, it is particularly preferable to install the cooling fan 2 in a region where the coating layer 13 adheres to the surface of the refractory inside the rotary kiln 1 from the kiln end on the attachment side of the burner 30, but outside the region. May be.

[Outline of cooling fan]
FIG. 3 is a perspective view of the cooling fan 2. A nozzle 3 is provided around the air outlet from the cooling fan 2, and water is blown from the nozzle 3 to be atomized to form a mist 4.

  The cooling fan 2 can effectively cool the kiln shell 5 without wetting the outer surface. Specifically, the particle size of the mist 4 is set to a very small size of 150 μm or less, and is evaporated before reaching the outer surface of the kiln shell 5. The flow of the cooling air 7 is formed by the cooling fan 2, and the temperature of the air flow including the mist 4 blown out toward the cooling air 7 is lowered by the evaporation heat of the mist 4. The outer surface of the kiln shell 5 is cooled by the air flow having the lowered temperature reaching the kiln shell 5.

  The nozzles 3 are provided at regular intervals around the blowout port, and are inclined inwardly toward the central direction of the flow of the cooling air 7 (the axial center direction of the cooling fan 2) (angle is 30 ° to 60 °). °). This is because when the angle is less than 30 °, spraying is not performed on the entire cross section of the air flow, whereas when the angle exceeds 60 °, the air flow is disturbed and the uniform air flow is hindered. In addition, what is necessary is just to enlarge the inclination | tilt angle of the nozzle 3, so that the blowing wind speed of the cooling air 7 is quick.

The number of nozzles 3 is determined according to the required amount of water and the discharge capacity of the nozzles. In order to cool the temperature of the cooling air 7 uniformly, it is effective to disperse and install the nozzles 3, and about 6 to 50 cooling fans 2 are provided per unit. If it is 5 or less, it is difficult for the fog 4 to be uniform. If the number of nozzles exceeds 50, piping to the nozzle 3 becomes complicated, and disposing it at the air outlet of the cooling fan 2 is physically difficult in the first embodiment, although it depends on the nozzle diameter. It is.

  The particle diameter of the mist 4 is 10 to 150 μm. With this particle size, the mist 4 evaporates by the air flow formed by the cooling fan 2 before reaching the outer surface. Therefore, the temperature of the air flow is lowered by the heat of evaporation without wetting the outer surface of the kiln shell 5, and the kiln shell 5 can be cooled.

  If the size of the mist droplets exceeds 200 μm, some of the mist droplets cannot be vaporized before reaching the kiln shell at the temperature of the cooling air 7, and the mist droplets may collide with the kiln shell 5. The amount of water supplied is 30 to 270 l / hr for each cooling fan 2. The flow rate is adjusted by the size of the spray nozzle and the spray pressure. The spray pressure of the nozzle part is 0.3 to 6 MPa.

  Here, the temperature of the outer surface of the kiln shell 5 is normally 250 to 400 ° C., and the original air temperature of the cooling fan 2 is 50 to 150 ° C. Therefore, the mist 4 sprayed from the nozzle 3 is instantaneously applied. It is possible to vaporize.

  Even if cooling air is generated by the evaporation heat of the mist 4, if the distance from the nozzle 3 to the kiln shell 5 is excessive, the temperature rises before reaching the outer surface by the radiant heat from the kiln shell 5, and the kiln shell The cooling efficiency of 5 is reduced. On the other hand, if the distance from the nozzle 3 to the kiln shell 5 is too short, the time until the mist 4 reaches the outer surface is shortened, and sufficient time for evaporation cannot be secured. Therefore, in Embodiment 1, the distance from the nozzle 3 to the kiln shell 5 is preferably in the range of 0.6 to 3 m. This is because if the distance is less than 0.6 m, the evaporation time is insufficient, and if it exceeds 3 m, the temperature of the cooling air rises.

[Relationship between the updraft around the kiln and the cooling effect]
On the outer surface of the kiln shell 5, an updraft 20 is formed by the heat of the rotary kiln 1 (see FIG. 2). By causing the ascending airflow 20 to be accompanied by the cooling air 7 from the cooling fan 2, the cooling air 7 is introduced over the outer surface of the kiln shell 5 and is effectively cooled.

  Further, the kiln shell 5 rotates in the clockwise direction as the rotary kiln 1 rotates. Therefore, the relative motion between the kiln shell 5 and the cooling air 7 is in the reverse direction on the x-axis positive direction side and the forward direction on the x-axis negative direction side with respect to the rotation axis L of the rotary kiln 1. Since the relative speed difference between the cooling air 7 and the peripheral speed of the kiln shell 5 increases on the x-axis positive direction side, which is the opposite direction, the forced convection heat transfer speed increases and the cooling effect is improved. On the other hand, when the relative speed between the cooling air 7 and the rotation of the kiln shell 5 is the forward direction, the cooling air 7 rides on the rotation of the kiln shell 5 and diffuses to the outer surface of the kiln shell 5, thereby effectively cooling the outer surface. Note that the temperature difference between the air and the kiln shell 5 widens as much as the amount of heat generated by the evaporation heat of the mist 4.

[Relationship between burner and cooling position]
FIG. 4 is a diagram showing a temperature distribution in the y-axis direction of the rotary kiln 1. In the rotary kiln 1, the vicinity of the tip of the flame ejected from the burner 30 has the highest temperature, and the coating layer 13 adheres to the area where the flame exists, but the thermal burden on the kiln shell 5 is large. Therefore, the cooling fan 2 is provided in the vicinity of the flame tip of the burner 30 as described above, and the kiln shell 5 is effectively cooled by blowing the cooling air 7.

  Also, assuming that the total length of the rotary kiln 1 is Y, the region of the rotary kiln 1 where the flame of the burner 30 exists is directed from the burner 30 side end of the rotary kiln 1 toward the flame injection direction (y-axis positive direction side) of the burner 30. Thus, it is substantially within the range of (1/3) Y.

  Accordingly, by blowing the cooling air 7 from the end of the rotary kiln 1 on the burner 30 side toward the flame injection direction (y-axis positive direction side) of the burner 30 in the range of about (1/3) Y, the rotary kiln 1 The region where the cooling requirement is highest among 1 is effectively cooled.

  In FIG. 1, the kiln shell 5 is cooled using the two cooling fans 2, but the coating layer 13 adheres to the cooling air 7 including the mist 4 from the attachment portion of the burner 30 toward the positive side of the y-axis. What is necessary is just to blow 1 or more places to the area | region (or the area | region of about (1/3) Y toward the flame injection direction of the burner 30) (refer Embodiment 4 in the case of multiple). Further, in places other than the above region, an air-cooled fan that does not include the mist 4 may be used as appropriate. Moreover, when it is desired to enhance the cooling effect by design, the cooling air 7 including the mist 4 may be blown using a cooling fan 2 in a place other than the above-described region. Further, the number of cooling fans 2 may be appropriately changed according to the required cooling performance.

Advantages of Embodiment 1 (1) In a rotary kiln cooling method in which a refractory material (refractory brick 12) is provided on the inner surface, fuel is burned by a burner 30 provided on one end side, and a workpiece is heated, the rotary kiln 1 The mist 4 is sprayed on the cooling air 7 blown toward the outer surface vertically downward (on the z-axis negative direction side) from the rotation axis.
Thereby, it becomes possible to introduce the cooling air 7 including the mist 4 output from the cooling fan 2 over the outer surface by using the rising airflow 20 generated on the outer surface of the kiln shell 5, and effectively cool the kiln shell 5. can do. Further, by cooling the air blown from the cooling fan 2 by the evaporation heat of the mist 4 to generate the cooling air 7, the air is cooled without wetting the outer surface of the kiln shell 5, and the temperature of the outer surface of the kiln shell 5 by the infrared thermometer is measured. Can be measured correctly.

(6) The object to be processed is melted by the heat of the burner 30, and forms the coating layer 13 by adhering to the inner peripheral surface of the refractory,
The cooling air 7 is air blown at one or more places on the outer surface of the rotary kiln 1 and in the region where the coating layer 13 is formed. Thereby, the vicinity of the burner 30 which becomes the highest temperature in the rotary kiln 1 can be appropriately cooled.

(7) Cooling air 7 is the outer surface of rotary kiln 1 and is blown at one or more locations within a predetermined range.
This predetermined range is a range of (1/3) Y from the burner 30 side end of the rotary kiln 1 toward the flame injection direction of the burner 30, where Y is the total length of the rotary kiln 1.
Thereby, the effect similar to said (6) can be acquired.

(8) The amount of water droplets contained in the fog 4 is variable.
Thereby, the amount of cooling can be changed as appropriate depending on the temperature of the kiln shell 5.

(9) There are a plurality of positions where the cooling air 7 is blown, and the amount of water droplets can be controlled independently at each position.
Thereby, in the kiln shell 5, the quantity of the water droplet injected to the position which wants to increase the cooling amount can be increased suitably.

[Embodiment 2]
The second embodiment will be described. The basic configuration is the same as in the first embodiment. In the first embodiment, the cooling air 7 from the cooling fan 2 is blown toward the z-axis positive direction side, but in the second embodiment, the cooling air 7 is inclined to the x-axis direction side (the circumferential direction of the kiln shell 5) with respect to the z-axis. It differs in that it blows air.

FIG. 5 is a radial sectional view of the rotary kiln 1 according to the second embodiment, and FIG. 6 is a diagram showing a cooling position by the cooling fan 2. As shown in FIG. 6, the refractory brick 1 is placed in the kiln shell 5.
2 is provided, and the raw material 9 is fired on the inner peripheral side thereof. For the sake of explanation, the updraft 20 is omitted in FIG.

  Although the raw material 9 is biased toward the negative z-axis side due to the influence of gravity, the surface of the raw material 9 is melted and becomes sticky because it is baked at a high temperature, and the refractory fires as the kiln shell 5 rotates clockwise. The frictional resistance between the brick 12 and the furnace wall surface 11 or the coating layer 13 is increased and scraped up by the rotating furnace wall surface 11. For this reason, the raw material 9 is scraped up vertically (z-axis positive direction side) on the x-axis negative direction side. On the other hand, the x-axis positive direction side of the raw material 9 moves vertically downward (z-axis negative direction side) as the kiln shell 5 rotates clockwise.

  Here, although the high temperature gas 10 is introduced into the kiln shell 5, the high temperature gas 10 is not in contact with the raw material 9 through the refractory brick 12 and / or the coating shell 13 in the kiln shell 5. Therefore, the kiln shell 5 rises in temperature at the high temperature gas contact portion D1 that directly contacts the high temperature gas 10 via the refractory brick 12 and / or the coating shell 13, and the raw material that contacts the raw material via the refractory brick 12 and / or the coating shell 13 is used. The temperature decreases at the contact portion D2.

  Further, since the kiln shell 5 rotates in the clockwise direction, the time of contact with the high temperature gas contact portion D1 increases as the rotation increases, and the temperature also rises, and the region immediately before contact with the raw material 9 on the x axis positive direction side (high temperature gas) 10 and the raw material 9 is the highest temperature in the boundary region D3). Accordingly, the kiln shell 5 has the greatest cooling demand in the boundary region D3.

  Therefore, in the second embodiment, in order to cool the boundary region D3, the blowing direction of the cooling air 7 from the cooling fan 2 is inclined from the z-axis positive direction side (vertical) to the x-axis positive direction side. As a result, the cooling air 7 is directly blown to the boundary region D3, and the part of the kiln shell 5 that needs the most cooling is effectively cooled. In the second embodiment, the tilt angle is 3 ° to 30 °, but may be appropriately changed depending on the shapes and positional relationships of the kiln shell 5 and the cooling fan 2.

  The inclination angle is increased in proportion to the diameter of the rotary kiln 1. However, if the inclination angle is excessive, the cooling air flows to the outer peripheral side (the positive and negative directions of the x axis) of the rotary kiln 1. It becomes difficult to reach. In addition, if the inclination angle is too small, the cooling air 7 directly hits the lower part of the shell and causes local cooling, while the cooling air 7 hardly reaches the upper part of the kiln shell 5.

  Since the boundary region D3 is located on the positive side of the x-axis with respect to the rotation axis L of the kiln shell 5, the relative speed difference between the cooling air 7 and the rotation of the kiln shell 5 is increased as in the first embodiment. The convection heat transfer rate is increased and the cooling effect is improved (see FIG. 5).

Effect of Embodiment 2 (2) The cooling air 7 is blown while being inclined in the circumferential direction of the rotary kiln 1 with respect to the vertical axis (z-axis).
Accordingly, it is possible to appropriately cool the boundary area D3 and the like where the cooling request is high.

[Embodiment 3]
The third embodiment will be described. The basic configuration is the same as that of the second embodiment. In the second embodiment, the cooling air 7 including the mist 4 is inclined in the circumferential direction of the rotary kiln 1, but in the third embodiment, the cooling air 7 is inclined in the axial direction of the rotary kiln 1.
FIG. 7 is a side view of the rotary kiln 1 according to the third embodiment. In the third embodiment, the cooling fan 2 is inclined in the rotation axis direction (y-axis direction) of the rotary kiln 1 and the cooling air 7 is injected to a desired position in the y-axis direction.

Effects of Embodiment 3 (3) The cooling air 7 is blown while being inclined in the axial direction of the rotary kiln 1 with respect to the vertical axis (z-axis).
Thereby, a cooling position can be made variable in the axial direction of the rotary kiln 1, and a desired position can be cooled effectively.

[Embodiment 4]
The fourth embodiment will be described. In the first to third embodiments, one row of cooling fans 2 is provided in parallel or substantially parallel to the y-axis, but the fourth embodiment is different in that two rows are provided.

8 is a radial cross-sectional view of the rotary kiln 1 according to the fourth embodiment, and FIG. 9 is a side view. In the fourth embodiment, the cooling fans 2 are arranged in two rows parallel or substantially parallel to the y axis.
There may be two or more rows.

  The plurality of cooling fans 2 are arranged on two rows of rails 41 and 42 provided parallel or substantially parallel to the y-axis, and are independently provided on the rails 41 and 42 so as to be movable parallel to the y-axis. It has been. The cooling position of the kiln shell 5 can be changed as appropriate by appropriately moving the blowing position of the cooling air 7. Further, by providing the cooling fan 2 on the two rails 41 and 42, the cooling air 7 can be further spread over a wide range of the kiln shell 5, and the cooling efficiency is further enhanced.

  The cooling fan 2 provided on the rail 41 on the x-axis positive direction side is the x-axis positive direction cooling fan 21 and the cooling fan 2 provided on the rail 42 on the x-axis negative direction side is the x-axis negative direction cooling fan. Assuming that the distance between the cooling fans 21 and 22 on the x-axis positive and negative direction side is set to 1 m to 2 m. This is to set the distance between the cooling fans 21 and 22 on the x-axis positive and negative directions side to 1 m to 2 m so that the cooling air 7 flows over the entire lower surface of the kiln shell 5. With this arrangement, the kiln shell 5 is directly cooled by the cooling air 7 from the cooling fans 21 and 22.

In the fourth embodiment, similarly to the second embodiment, the cooling fan 2 is inclined in the x-axis direction with respect to the z-axis. The inclination angle of the blowout direction of the cooling fan 2 is inclined by 3 ° to 30 ° with respect to the z-axis so that the cooling air 7 is widely distributed over the outer surface of the kiln shell 5. As a result, the same effect as in the second embodiment can be obtained.

Effects of Embodiment 4 (4) The blowing position of the cooling air 7 can be translated with respect to the rotation axis (y-axis direction) of the rotary kiln 1.
By appropriately moving the blowing position of the cooling air 7, the cooling position of the kiln shell 5 can be changed as appropriate.

(5) The cooling air 7 is blown from the cooling fan 2,
Rails 41 and 42 that are parallel or substantially parallel to the rotation axis of the rotary kiln 1 are provided, and the cooling fan 2 is provided so as to be movable on the rails 41 and 42.
Thereby, the cooling fan 2 can be easily moved in parallel based on a simple configuration. Note that Embodiments 1 to 4 may be appropriately combined as desired.

  INDUSTRIAL APPLICABILITY The present invention is a technique that can be applied to any industrial furnace that uses a rotary kiln to monitor the outer surface temperature of the kiln shell and manage the temperature below a reference value, and the maximum temperature in the furnace is particularly high. The furnace is more effective. There are many industries that use rotary kilns such as quicklime production, lightweight aggregate production, dolomite production, blast furnace dust reduction, and various waste treatment (incineration ash, waste plastic, waste oil, waste liquid, waste wood, dewatered sludge, etc.) In any industry, the present invention can be applied.

DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Cooling fan 3 Nozzle 4 Mist 5 Kiln shell 7 Cooling air 9 Raw material 10 High temperature gas 11 Furnace wall 12 Refractory brick 13 Coating layer 14 Duct 15 Outlet 21 Cooling fan 22 Cooling fan 30 Burner 41 Rail 42 Rail

Claims (10)

In the cooling method of the rotary kiln in which the refractory is provided on the inner surface, the fuel is burned by the burner provided on one end side, and the workpiece is heated,
A method for cooling a rotary kiln, characterized in that mist is sprayed on cooling air blown toward an outer surface vertically downward from a rotary shaft of the rotary kiln. In the cooling method of the rotary kiln according to claim 1,
The method of cooling a rotary kiln, wherein the cooling air is blown with respect to a vertical axis while being inclined in a circumferential direction of the rotary kiln. In the cooling method of the rotary kiln according to claim 1,
The method of cooling a rotary kiln, wherein the cooling air is blown with an inclination in an axial direction of the rotary kiln with respect to a vertical axis. In the cooling method of the rotary kiln according to any one of claims 1 to 3,
The method for cooling a rotary kiln, wherein the cooling air blowing position is movable in parallel with the rotary axis of the rotary kiln. In the cooling method of the rotary kiln according to claim 4, a rail parallel to the rotation axis of the rotary kiln is provided, and the cooling air is blown from a cooling fan,
The method for cooling a rotary kiln, wherein the cooling fan is provided so as to be movable in parallel on a rail. In the cooling method of the rotary kiln according to any one of claims 1 to 5,
The object to be treated is melted by the heat of the burner and forms a coating layer by adhering to the inner peripheral surface of the refractory,
The cooling air is cooled on the outer surface of the rotary kiln, and is blown into at least one area where the coating layer is formed. In the cooling method of the rotary kiln according to any one of claims 1 to 5,
The cooling air is blown at least one place within a predetermined range on the outer surface of the rotary kiln,
The predetermined range is a range of (1/3) Y from the burner side end portion of the rotary kiln toward the flame injection direction of the burner, where Y is the total length of the rotary kiln. Cooling method. In the cooling method of the rotary kiln according to any one of claims 1 to 7,
A method for cooling a rotary kiln, wherein the amount of water droplets contained in the mist is variable. The method for cooling a rotary kiln according to claim 8,
The cooling method for a rotary kiln, wherein the cooling air has a plurality of blowing positions, and the amount of the water droplets can be controlled independently at each position. With rotary kiln,
In a rotary kiln cooling device having a cooling fan,
Further provided with a mist spraying means,
The cooling fan blows cooling air to the outer surface vertically below the rotary shaft of the rotary kiln,
The said mist spraying means sprays mist on the said cooling air. The cooling device of the rotary kiln characterized by these.

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