JPH0520676B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an ejector nozzle for a device that uses an ejector system to suction and remove slag generated in the ironmaking and steelmaking processes.

[Conventional technology]

Methods for removing slag generated during pig iron and steel making processes include scraping out slag floating on hot metal or molten steel with a slag dragger (scraping method);
There are two methods: a method in which hot metal or molten steel is extracted from the bottom of a container and slag remains in the container (remaining hot metal method), and a method in which slag floating on top of the hot metal or molten steel is sucked up and removed by suction force (suction method). Of these, the scraping method has the inconvenience of scraping out hot metal and molten steel together with slag, while the residual method cannot avoid molten metal loss due to hot metal and molten steel remaining in the container, both of which lead to a decrease in yield. is mainly used. As the suction method, the following methods are known. (a) Slag removal equipment using a suction device such as a vacuum pump or rotary blower
26398). This device suctions slag from a suction port connected to a suction device, cools and solidifies the suction slag with a water injection device installed near the suction port, and collects the solidified slag, water, and water vapor generated by the slag cooling into the suction device. This is a method that separates and discharges the waste before it reaches this point. (b) Method of jetting gas instead of water jetting for cooling and solidifying slag (Japanese Patent Laid-Open No. 62-4839). This method was proposed for suctioning slag floating on fixed melting point molten metals such as zinc.
The suction pipe connected to a suction device such as a vacuum pump is a double pipe with a sealed water-cooled jacket structure, and the suction slag is crushed and cooled by blowing out gas toward the downstream side in the suction direction inside the suction port. This method separates and discharges the suction airflow and slag before the suction device. (c) Dry slag removal method using a gas ejector without using water (Japanese Patent Application Laid-Open No. 165588/1983). As shown in the schematic diagram in FIG. 8A, this method uses an edge structure in which a suction pipe 1 and a discharge pipe 2 are connected at right angles, and a driving nozzle 3 for injecting a gas jet is attached to the rear end of the discharge pipe 2. This method uses an Ector nozzle to remove slag by suction.

[Problems with conventional technology]

However, the conventional suction methods (a) to (c) have the following drawbacks. The slag removal device shown in (a) injects water to cool the slag near the suction port, and there is a risk of a steam explosion due to backflow of water to the molten metal surface due to equipment failure. Further, a vacuum pump as a suction device, a slag separator, a steam condenser, etc. are required, and the equipment cost is high. The gas jetting method in (b) uses cooling water, albeit indirectly, to cool the suction pipe, and if there is a problem with the cooling water delivery device, melting of the suction pipe, or damage due to external force, the cooling water may run out. There is a risk of leakage onto the molten metal, so safety must be taken into consideration, and there are problems such as equipment costs and installation space for suction devices such as vacuum pumps and slag separators. The dry slag removal method in (c) does not use water, so it is not suitable for (a) above.
It is safer than method (b), and because it suctions slag by using the negative pressure generated by pressurized gas jets without using a suction device such as a vacuum pump, there are no moving parts and equipment. It has the advantage of being low in cost and maintenance cost, and requiring only a small installation space. However, there are problems as shown below. As shown in FIG. 8B, this type of ejector system uses gas injected from a drive nozzle 3 provided at the rear of the discharge pipe 2 to move the suction pipe 1.
By creating a negative pressure inside, the slag 5 on the surface of the molten metal 4 is sucked and discharged from the discharge pipe 2. However, this method has the drawback that the inner walls of the suction tube 1 and the discharge tube 2 are significantly eroded and damaged by the attracted high-temperature slag, and the durability of the suction tube and the discharge tube is reduced. In addition, in the case of slag with high viscosity and poor fluidity, as shown in FIG. 8B, the sucked slag adheres to the inner walls of the suction pipe 1 and the discharge pipe 2, with particularly large adhesion to the inner walls of the discharge pipe. There was a problem in that the inner diameter of the tube was reduced by the accumulated slag 5, resulting in a decrease in suction performance. This invention is a slag suction and removal device that solves the conventional problem (c), that is, a decrease in durability due to melting of the suction tube and discharge tube, and a decrease in suction performance due to slag adhesion to the inner wall of the suction tube and discharge tube. This paper aims to propose an ejector nozzle.

[Means to solve the problem]

As a means of solving the above-mentioned conventional problems, this invention arranges a jetting nozzle of the driving fluid near the inner wall of the suction pipe, so that the inner surfaces of the suction pipe and the discharge pipe are cooled by the temperature drop caused by the sudden expansion of the driving jet. In addition, by smoothing the flow of slag in the suction pipe and discharge pipe, melting loss and slag adhesion are prevented. An annular slit nozzle is provided on the pipe wall directly above the mouth, and the ejection angle of the driving fluid is 45 degrees or less with respect to the pipe wall, and a straight pipe part having a length of at least twice the inner diameter of the suction pipe is formed from the annular slit. The main feature is that a discharge curved pipe having a radius of curvature of four times or more than the inner diameter of the suction pipe is connected to the straight pipe part, and the suction pipe part and the discharge curved pipe part are double pipes, and the inner pipe and It is characterized by having a structure in which the driving fluid flows through the gap between the outer tube and the suction port portion being made of a porous material. That is, as a measure to prevent erosion of conventional dry ejectors, this invention cools the inner wall of the tube and cools and solidifies the molten slag by making the driving fluid jet nozzle into an annular slit and placing it directly above the suction port. Was it. The suction tube section and the discharge curved tube section have a double tube structure, and by circulating the driving fluid between the inner tube and the outer tube, the cooling effect of the inner tube is further enhanced. In addition, as a measure to prevent slag adhesion, the suction port is shaped like a wrapper, and the discharge pipe is made of a curved pipe with a large radius of curvature, allowing the suction slag to flow smoothly. The rattling-shaped suction port is made of a porous material, and a portion of the driving fluid is leached from the porous material into the pipe to form a gas film on the inner surface of the suction port, thereby preventing slag from adhering to the suction port. .

[Effect]

FIG. 1 is a longitudinal sectional view showing a preferred ejector nozzle of the present invention, in which 11 is a suction pipe, 11-1 is a wrapper pipe, 11-2 is a straight pipe part, 12 is a discharge curved pipe, 1
3 represents a driving fluid supply pipe, and 14 represents an annular slit nozzle. The annular slit nozzle 14 includes a wrapper tube 1
1-1 and the straight pipe part 11-2 so that the ejection angle θ of the driving fluid is 45 degrees or less with respect to the suction pipe wall. Here, the ejection angle θ of the driving fluid was limited to 45 degrees or less, as shown in Figure 2, which shows the relationship between the ejection angle θ of the driving fluid and the suction efficiency.
This is because suction efficiency of 80% or more can be ensured by setting the temperature to 80% or less. In addition, the straight pipe portion 1 at the upper part of the slit nozzle 14
1-2 has a length L that is more than twice the inner diameter D of the suction tube. As shown in Figure 3, which shows the relationship between the ratio L/D of the straight pipe length L and the inner diameter D, and the suction efficiency, it is 80% unless the straight pipe length is more than twice the suction pipe inner diameter D.
This is because the suction efficiency above cannot be obtained. The radius of curvature of the discharge curved pipe 12 is the inner diameter D of the suction pipe.
4 times or more. The reason is as shown below. Using an experimental ejector, we sucked up hydrated clay sand and examined how it adhered to various parts.
While there was almost no adhesion to the upper straight pipe part of the nozzle, a lot of adhesion occurred outside the curved discharge pipe part. Therefore, as a result of repeating adhesion experiments with various radius of curvature of the discharge pipe, the radius of curvature of the discharge pipe was changed to the inner diameter as shown in Figure 4, which shows the relationship between the radius of curvature R/D of the curved pipe and the maximum adhesion thickness t/D. It was found that when the amount was increased to 4 times or more of D, the amount of adhesion decreased significantly, and when it was increased to 6 times or more, there was almost no adhesion. Based on this knowledge, the radius of curvature of the discharge curved pipe was set to be four times or more the inner diameter of the suction pipe. The results shown in FIG. 4 are obtained by conducting several experiments using curved discharge pipes with the same radius of curvature, and plotting the maximum and minimum values of the maximum adhesion thickness measured in each experiment. Ratsupa tube 11-1 constituting suction tube 11
The straight pipe portion 11-2 is integrated with the drive fluid supply pipe 13. In the case of the ejector nozzle having the above structure, the driving fluid supplied from the driving fluid supply pipe 13 is injected as a jet flow from the annular slit nozzle 14, and this jet flow creates a negative pressure inside the suction pipe 11. The floating slag 5 on the surface of the molten metal 4 is sucked through the suction port 11-3 of the slug pipe 11-1 and discharged from the discharge port 12-1 of the discharge curved pipe 12. At this time, since the driving fluid is injected at an angle of 45 degrees or less with respect to the suction pipe wall, the temperature drop due to the rapid expansion of the driving jet causes the suction pipe 11 and the discharge bent pipe 1 to
While the inner surface of the molten slag 2 is cooled, the molten slag 5 is also cooled and solidified. Therefore, melting damage of the suction pipe 11 and the discharge curved pipe 12 is reduced, and the durability of the ejector is improved. In addition, since the slag suction port 11-3 has a flat shape, the floating slag on the surface of the molten metal is smoothly suctioned, and since the discharge curved pipe 12 is constructed of a curved pipe with a large radius of curvature, the suction tube 11
The fluid also flows smoothly inside the discharge curved pipe 12. Therefore, in combination with the cooling effect, almost no slag is attached to the suction pipe 11 and the discharge curved pipe 12.

[Preferred embodiment of the invention]

5, 6, and 7 show preferred embodiments of the present invention. In FIG. 5, the suction pipe section and the discharge pipe section have a double pipe structure, and the gap between the inner pipe and the outer pipe is An example of a structure in which the driving fluid flows is shown below. Moreover, FIG. 6 shows an example in which the suction port of the Lampa tube is formed of a porous material. Moreover, FIG. 7 shows an example in which the pipe inner wall on the discharge side of the discharge curved pipe section is cut out in the pipe axis direction. That is, the ejector nozzle shown in FIG. -4, 22-4, and the distribution pipe 2 is connected to the outer pipe 22-4 of the discharge bent pipe 22.
2-5 to connect the driving fluid supply pipe 23 between the inner pipe 22-3 and the outer pipe 22-4 of the discharge curved pipe part and between the inner pipe 21-3 and the outer pipe 21-4 of the suction pipe part. At the same time, the driving fluid is guided to the wrapper tube 21-1 section from the driving fluid distribution perforated plate 25 provided at the lower part of the suction tube section, and is sucked through the annular slit nozzle 24 provided on the inner wall of the suction tube. It has a structure that injects driving fluid into the pipe. In the case of such a structure, the cooling effect of the inner tubes 21-3 and 22-3 is further enhanced by the driving fluid flowing between the inner tube and the outer tube of the suction tube section and the discharge curved tube section. In addition, as shown in FIG. 6, by using a wrapper tube 21-5 whose inner wall is made of a porous material 21-6, the driving fluid that flows between the inner tube and the outer tube and is guided to the wrapper tube section. is leached from the porous material 21-6 to form a gas film on the inner surface of the tube, thereby preventing slag from adhering to the suction port. Note that porous brick is suitable as the porous material. Furthermore, Fig. 7 shows an example in which the inner wall inside the discharge port is notched vertically in order to prevent slag adhesion near the discharge port, and Fig. 7 A shows an example in which the notch 26 is formed with the same curvature as the discharge curved pipe. Figure B shows an example in which an oblique notch 27 is formed, and in this case, the notch angle ψ is preferably in the range of 90 to 180 degrees. When the inner wall of the discharge port part is notched as described above, slag does not adhere to the part, and the slag that has adhered to the outside of the discharge bent pipe part can be easily peeled off.

【Example】

Example 1 Table 1 shows the state of slag adhesion when suction of molten blast furnace slag was carried out using the ejector nozzle with the single tube structure shown in FIG. 1, in comparison with the conventional nozzle shown in FIG. This slag adhesion status is 3 to 10
This is the situation after suctioning 40~350Kg of molten blast furnace slag in a suction time of 1 minute. The dimensions of the ejector nozzle used in this example are: inner diameter D80.7mm, discharge curved pipe curvature radius R500mm.
(6.2 times the inner diameter), straight pipe length L268mm (3.3 times the inner diameter)
(times)) The annular slit nozzle had a jet angle θ of 22.5 degrees and a slit gap of 0.67 to 1.42 mm. Furthermore, N ₂ gas was used as the driving fluid. Note that the conventional nozzle had an inner diameter of 80.7 mm and a drive fluid ejection nozzle diameter of 21.6 mm. As is clear from Table 1, in the conventional T-shaped ejector nozzle, a large amount of slag adhered to the suction tube and the discharge tube, resulting in a decrease in suction performance, whereas in the ejector nozzle of the present invention, the suction opening of the lapper tube section Although a slight amount of slag adhered to the surface, it did not affect the suction performance and could be easily peeled off with a light impact.
No slag adhesion occurred on the straight pipe section or the discharge curved pipe section.

【table】

[Table] Example 2 An ejector nozzle with a double pipe structure shown in Fig. 5 was used, and the bulge-shaped suction port was made of steel and porous brick (air permeability 0.1cm ⁴ /g・s, thickness 15mm). Table 2 shows the state of slag adhesion when suctioning molten KR desulfurization slag using different types of nozzles. This slag adhesion situation can be seen with a suction time of 4 to 19 minutes.
This is the situation after sucking 70 to 600 kg of KR desulfurization slag. The dimensions of the ejector nozzle used in this example are: inner diameter D105 mm, curvature radius R650 (6.2 mm of inner diameter
), straight pipe length L370mm, slit nozzle discharge angle θ22.5°, and slit gap 0.71~1.66mm,
The distance between the inner tube and the outer tube, which is the flow path for the driving fluid, was 8 mm. _N2 gas was used as the driving gas. As is clear from Table 2, no slag adhesion occurred on the straight pipe section or the bent discharge pipe section. However, in the case of the steel suction port, although a slight amount of slag was observed on the suction port, it had no effect on suction performance and could be easily peeled off with a light impact after suction. On the other hand, in the suction port made of porous brick, no slag adhesion occurred due to the effect of gas leaching.

【table】

【Effect of the invention】

As explained above, the ejector nozzle of the present invention has the following effects. The inner surfaces of the suction and discharge tubes are cooled by the drive jet ejected from the annular slit nozzle located directly above the suction port, which greatly reduces melting damage on the inner walls of the tubes and improves durability. By making the slag suction port into a flat shape and the discharge pipe into a curved pipe with a large radius of curvature, slag suction and flow are smooth, and slag adhesion to the inner surfaces of the suction and discharge pipes is prevented, resulting in high suction. Gain efficiency. By forming the suction pipe and the discharge curved pipe into a double pipe structure, the cooling effect of the inner pipe is further enhanced by the driving fluid flowing between the inner pipe and the outer pipe. By configuring the suction port with a porous material such as porous brick, it is possible to prevent slag from adhering to the suction port due to exudation of the driving fluid. By cutting out the inner wall of the discharge port part, it is possible to completely eliminate slag adhesion to the part.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a preferred ejector nozzle of the present invention. FIG. 2 is a diagram showing the relationship between the drive fluid ejection angle θ and the suction efficiency in the nozzle. FIG. 3 is a diagram showing the relationship between the straight pipe length and suction efficiency in the same nozzle. FIG. 4 is a diagram showing the relationship between the radius of curvature of the curved discharge pipe and the maximum adhesion thickness of slag in the nozzle. Figure 5~
FIG. 7 shows a preferred embodiment of the present invention.
The figure is a vertical cross-sectional view showing an ejector nozzle with a double pipe structure, Figure 6 is a vertical cross-sectional view showing an example in which the suction port is made of a porous material, and Figure 7A is a vertical cross-sectional view showing an example in which the suction port is made of a porous material. A front view showing an example in which the discharge tube is notched, and FIG. FIG. 8A is a longitudinal sectional view showing a conventional ejector nozzle, and FIG. 8B is a longitudinal sectional view showing the usage state of the same nozzle. 11...Suction tube, 11-1...Ratsupa tube, 11
-2... Straight pipe section, 12... Discharge curved pipe, 13... Driving fluid supply pipe, 14... Annular slit nozzle,
21-3, 22-3...inner pipe, 21-4, 22-
4... Outer tube, 21-6... Porous material.

Claims (1)

[Scope of Claims] 1. In an ejector nozzle of a device for suctioning and removing slag floating on the surface of molten metal using an ejector method, a suction port is formed in the shape of a rattle, and a driving fluid is provided on a tube wall directly above the suction port. An annular slit nozzle whose ejection angle is 45 degrees or less with respect to the pipe wall, a straight pipe part extending from the annular slit nozzle to a length of at least twice the inner diameter of the suction pipe, An ejector nozzle for suctioning and removing slag, characterized in that a discharge curved pipe having a radius of curvature twice or more is connected to the straight pipe part. 2 The suction port, straight pipe, and discharge curved pipe are double pipes, with a structure that allows the driving fluid to flow between the inner pipe and the outer pipe, and an annular slit nozzle is provided in the inner pipe. An ejector nozzle for suctioning and removing slag according to claim 1. 3. The ejector nozzle for suctioning and removing slag according to claims 1 and 2, wherein the suction port in the shape of a rattle is made of a porous material. 4 Claims 1 and 2, characterized in that the pipe inner wall inside the discharge port of the discharge curved pipe portion is cut out.
Ejector nozzle for suctioning and removing slag as described in section.