JPH04123237U - Melting reduction furnace - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a smelting reduction furnace equipped with a pulverized coal injection lance that is highly suitable for reforming exhaust gas generated from the smelting reduction furnace. [Structure] A through hole is provided in the furnace wall at the furnace shoulder, which slopes downward from the outside of the furnace to the inside of the furnace, and this through hole is equipped with a fan-shaped pulverized coal blowing nozzle that forms an upward pulverized coal blowing port at the tip. A pulverized coal injection lance for reforming is inserted into the furnace so that it can move forward and backward, and the pulverized coal injection lance can be rotated around its axis as necessary, The pulverized coal is effectively diffused and brought into contact with the flue gas area in the furnace where the gas reforming effect is large, improving the reforming reaction efficiency for the flue gas, and reducing the amount of unreacted pulverized coal falling into the slag bath, thereby promoting the smelting and reduction reaction. Prevent loss of efficiency.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention uses the exhaust gas generated during smelting reduction as the reducing gas in the preliminary reduction device. This relates to a smelting reduction furnace equipped with a pulverized coal blowing lance for exhaust gas reforming. be.

0002

[Conventional technology]

Conventionally, fine ore is pre-reduced using a pre-reducing device and then melted in a smelting reduction furnace. Iron manufacturing technology that obtains molten iron by melting and reducing is known.

[0003] In this technology, the exhaust gas generated in the smelting reduction furnace is generally used as the reducing gas in the preliminary reduction device, and in order to increase its reducing power, (CO ₂ + H ₂ O)/( It has become common practice to carry out gas reforming to increase the degree of oxidation (OD) of the gas, expressed as CO ₂ +CO + H ₂ +H ₂ O).

0004 As a means of reforming this gas, generally speaking, gas reforming mainly consisting of coal powder is used in the exhaust gas. A method is known in which the sensible heat of the exhaust gas is used as a heat source for the reaction (endothermic) by injecting a bulking agent into the reactor. For example, the injection of this modifier is carried out as in JP-A-63-140012. The flue installed above the fusion furnace and the melting It is carried out from the furnace wall of a reduction furnace, or it is carried out using an acid as in JP-A No. 1-116020. It is known that the process is performed using a lance that also serves as a plain blowing lance.

[0005]

[Problem that the idea aims to solve]

Coal powder gas is used to reduce the degree of oxidation of flue gas from smelting reduction furnaces as described above. In coal powder reforming, the reforming effect is due to the vapors (VM) contained in the coal powder, which is the modifier. Exhaust gas tends to change depending on properties such as vaporization characteristics and particle size, operating conditions, furnace wall conditions, etc. Experiments conducted by the inventors revealed that the temperature and degree of oxidation depend on the condition of the exhaust gas. are doing.

[0006] However, in the conventional gas reforming mentioned above, gas reforming takes these changes into consideration. It is difficult to say that the injection of the modifier is being carried out, and the gas modifier is not being injected into the smelting reduction reaction zone. Some coal powder enters, reducing the smelting reduction efficiency, and this coal powder is also injected into the gas modifier. There is a problem in that the contribution decreases.

[0007] This invention is a highly suitable pulverized coal injection method for efficiently reforming exhaust gas in a smelting reduction furnace. The present invention provides a melting reduction furnace equipped with a safety check.

[0008]

[Means to solve the problem]

In this invention, a downwardly sloping through hole is provided in the furnace wall at the furnace shoulder above the iron bath surface. It is inserted into the furnace through a through hole so that it can move forward and backward, and there is an upward pulverized coal outlet at its tip. This is a smelting reduction furnace equipped with a fan-shaped pulverized coal injection lance for gas reforming. The lance is characterized by being rotatable about the axis of the lance according to the Ru.

[0009]

[Effect]

In the smelting reduction furnace of this invention, the injection position of pulverized coal can be adjusted with gas according to the furnace conditions. It can be adjusted to a position that provides conditions for efficient reaction, and is suitable for high-temperature exhaust gas flow. The pulverized coal is blown upward in a fan shape, dispersed, and brought into contact with the exhaust gas stream. It increases the viscosity and makes it possible to improve the gas reforming reaction.

0010

【Example】

Figure 1 shows a vertical cross-section of a part of a converter-type melting reduction furnace showing one embodiment of the present invention. 1 is a converter-type melting reduction furnace, with a furnace shell shell 2 and a lining inside it. The furnace wall is made of refractory bricks.

[0011] The furnace shoulder on the trunnion shaft side of this furnace wall has a slope of approximately 20° from the outside of the furnace to the inside of the furnace. A through hole 4 is provided in which a pulverized coal injection lance 5 is inserted into the furnace. It is inserted so that it can move forward and backward and rotate freely around its axis.

0012 The tip of this powdered coal injection lance 5 has a slit-shaped powdered coal outlet 6. As shown in FIG. 2, the fan-shaped pulverized coal blowing nozzle 7 has its axis Jc aligned with the pulverized coal blowing lamp. It is attached upward at an angle of 130° with respect to the axis C of the appliance.

[0013] As shown in FIG. It is not provided at right angles to the axis of the lance 5 but at an angle of about 10 degrees.

[0014] As shown in FIG. 4, this is due to the fact that the pulverized coal injection lance 5 This is because the pulverized coal injection runs on both sides are placed opposite each other in dry areas. When the base 5 is disposed directly facing the reactor core, it may be provided at right angles.

[0015] P is installed between the tip of the pulverized coal injection lance 5 and the pulverized coal inlet of the pulverized coal blowing nozzle 7. When introducing pulverized coal into the pulverized coal blowing nozzle 7 in the pocket section, uniform pulverized coal is spread. It has the function of forming a scattered flow and protecting the tip of the pulverized coal injection lance 5.

[0016] 8 is a gear provided on the pulverized coal injection lance 5 so as to be able to slide freely in the axial direction of the lance 5; It meshes with a gear 10 that is rotated by a lance rotation motor 9 provided at F. . 11 is a rack provided on the pulverized coal injection lance 5, and the lance advance provided on the support F. It meshes with a pinion 13 rotated by a retraction motor 12. 14 is inside the furnace It is an oxygen-blowing lance inserted into the core.

[0017] The pulverized coal injection structure shown in Fig. 1 is installed on the wall of the smelting reduction furnace 1 as shown in Fig. 4. The pulverized coal blowing lances 5 are provided facing each other, and the pulverized coal blowing lances 5 are provided facing each other. The pulverized coal blown out from the pulverized coal outlet 6 through the nozzle 7 is approximately 20° vertically. It has a spread of about 30 degrees to the left and right when viewed from above, and In the area above the tip (oxygen outlet) of the oxygen lance 14 in the center of the furnace, the exhaust gas Mix by vigorous contact with the gas stream. In normal operating conditions, this area is (a) in Figure 5. ), the gas flow is upward, and as shown in (b) of the same figure, the gas flow is at high temperature. High degree of oxidation.

[0018] Therefore, the powdered coal injected into this area will react from the area where the reaction effect is small. While spreading, contacting, and rising by this upward flow of exhaust gas flow in the area with a large effect. Since it reacts with the exhaust gas, the contact flight time is long and it fully contributes to gas reformation.

[0019] Therefore, the gas falls into the slag bath without contributing to gas reformation and reacts with smelting reduction. Since there is very little concern that the reaction will be inhibited, the melting reduction efficiency is also good.

[0020] This gas reforming generates a lot of gas, and the exhaust gas condition has a large gas reforming effect. It is preferable to carry out the operation under stable operating conditions when the bell is in a stable condition; Maintaining optimal operating conditions is difficult and fluctuations are common, so these conditions In response to changes in these conditions, we can determine the optimal pulverized coal injection conditions under those conditions. In order to obtain It is necessary to adjust the amount of pulverized coal injected.

[0021] In the present invention, this pulverized coal injection lance 5 can move forward and backward into the furnace, and The direction of the pulverized coal outlet 6 can be adjusted freely, and the amount of pulverized coal injected can be easily adjusted. By doing so, it has a structure that allows for easy adjustment as described above. be.

[0022] In addition, by combining with the detection means for detecting the condition inside the furnace, each inspection The information from the knowledge means is processed to determine the depth of the pulverized coal injection lance, the direction of the pulverized coal outlet, and the It is also easy to automatically adjust the amount of charcoal injection.

[0023] Reforming of exhaust gas in the converter type smelting reduction furnace of this example having the structure as described above. The results obtained when oxygen was blown in a converter type melting reduction furnace similar to the melting reduction furnace shown in Figure 1. Exhaust gas was reformed using a conventional method in which a pulverized coal inlet was formed around the outer periphery of the mirance. This will be explained below along with the results of the case (comparative example).

[0024] The basic operating conditions are as shown in Table 1, and are common to both the examples of the present invention and the comparative examples. powder The degree of oxidation of exhaust gas without charcoal injection is 44 to 54%, with an average of about 50%. It is.

[0025]

[Table 1]

[0026] Operating under these basic conditions, the exhaust gas is reformed by injecting powdered coal into the furnace, and the The exhaust gas from the furnace mouth from immediately after the start of injection to immediately after the end of injection is collected through the duct. During the process, an oxidation degree limiting device was installed and the oxidation degree was continuously measured. In the example, it was in the range of 32-40%, and the average was about 35%. i.e. book The idea is to reduce the degree of oxidation of exhaust gas by about 30%, which is almost satisfactory. The modification was completed. In addition, in this example, the slag bath level did not fluctuate widely. Adjust the insertion depth of the pulverized coal injection lance and oxygen injection lance, and the direction of the pulverized coal outlet. No adjustment was made.

[0027] On the other hand, in the comparative examples, the oxidation degree was in the range of 38 to 48, with an average of 42%. It became. In other words, in the comparative example, the degree of oxidation of exhaust gas could be reduced by about 16%; It is difficult to say that sufficient gas reforming was achieved.

[0028] The gas reforming results in this example and comparative example depend on the operating conditions, furnace wall condition, and properties of powdered coal. Although it varies slightly depending on the condition, blowing conditions, etc., in general, the gas reforming results as described above can be obtained. It will be done.

[0029] In addition, regarding the insertion angle of the pulverized coal injection lance in this invention, The pulverized coal of the pulverized coal blowing nozzle at the tip of the pulverized coal is oriented downward to prevent the inflow of slag. Powdered coal is supplied from the outlet to the area near the reactor core above the slag bath surface where the gas reforming reaction is good. It diffuses sufficiently to reach the destination, and its flight time is extended to ensure sufficient contact with the exhaust gas. In order to increase the efficiency of the gas reforming reaction, It is desirable to set the

[0030] In addition, the pulverized coal blowing nozzle installed at the tip of the pulverized coal injection lance is directed upward and downward. In other words, the pulverized coal outlet is installed to blow out the pulverized coal upward; The insertion angle is also related to the insertion angle and insertion depth of the pulverized coal injection lance. , as mentioned above, diffuse the pulverized coal to a region where the gas reforming reaction is favorable, and The flight time is increased to ensure sufficient contact with the exhaust gas, increasing the efficiency of the gas reforming reaction. Therefore, it should be set in the range of 90 to 140 degrees with respect to the axis of the pulverized coal injection lance. This is desirable. Furthermore, the diffusion angle of the pulverized coal blowout flow is 10 to 30 in the vertical direction. °, the pulverized coal blowing nozzle is set so that it is within the range of 20 to 50 degrees to the left and right when viewed from above. It is desirable to measure the

[0031] In addition, in this example, the pulverized coal injection lance can be rotated around its axis. The pulverized coal blowing nozzle is a slit shaped fan-shaped pulverized coal blowing nozzle. However, the length of this slit is shortened to reduce the diffusion angle. However, the pulverized coal injection lance may be rotated to widen the diffusion range over time. , in this case, in addition to slit-shaped speech bubbles, other round, square, triangular, oval, and polygonal speech bubbles A plurality of ports may be arranged in parallel. In addition, two pulverized coal injection lances were installed facing each other, but this Since this is a converter-type smelting reduction furnace that tilts, a pulverized coal injection lance is inserted on the tilting side. This is because it is difficult to For fixed smelting reduction furnaces, this pulverized coal injection run It is preferable to insert multiple screws (usually about 3 to 6) at approximately equal intervals around the furnace wall. Delicious.

[0032] In addition, the vertical position and direction of the pulverized coal blowing lance of this pulverized coal injection lance, etc. They do not all have to be the same; for example, if the insertion position of the oxygen injection lance is In such cases, the exhaust gas flow distribution will be biased, so in this case, the intervals may not be equal. In addition, it is effective to increase the gas reforming reaction efficiency by making the levels uneven. Ru.

[0033]

[Effect of the idea]

In this invention, the pulverized coal injection lance is tilted downward into the furnace. The depth of the pulverized coal can be adjusted, and the pulverized coal outlet can be adjusted upward from its tip. The gas condition inside the furnace, which has a large effect on the gas reforming reaction, can be controlled. The optimal pulverized coal injection position can be adjusted according to changes, ensuring that sufficient pulverized coal is injected into the exhaust gas. Through diffusion contact, the reaction efficiency of blown pulverized coal for exhaust gas reforming is improved, resulting in gas reforming. Prevents the mixing of powdered coal that does not contribute to the reaction into the slag, improving the efficiency of the smelting reduction reaction. can be done.

[Brief explanation of drawings]

FIG. 1 is an explanatory longitudinal cross-sectional view of a melting reduction furnace of the present invention.

FIG. 2 is an enlarged explanatory view of the tip of the pulverized coal injection lance in FIG. 1;

FIG. 3 is an explanatory plan view of FIG. 2;

FIG. 4 is an explanatory plan view showing the opposing arrangement of pulverized coal injection lances.

FIG. 5(a) is an explanatory diagram showing the gas flow rate distribution in the furnace in a steady operating state, and FIG. 5(b) is an explanatory diagram showing the in-furnace temperature distribution and oxidation degree distribution in the steady operating state.

[Explanation of symbols]

1 Melting reduction furnace 2 Furnace shell 3 Firebrick 4 Through hole 5 Powdered coal injection lance 6 Powdered coal outlet 7 Powdered coal blowing nozzle 8 Gears 9 Lance rotation motor 10 Gears 11 rack 12 Lance forward/backward motor 13 Pinion 14 Oxygen injection lance

──────────────────────────────────────────────── ─── Continuation of front page (72) Creator Masao Yamauchi Nippon Steel, 1 Chikko Yawatacho, Sakai City, Osaka Prefecture Inside Sakai Iron Works Co., Ltd.

Claims (2)

[Scope of utility model registration request] Claim 1: A through hole is provided in the furnace wall of the furnace shoulder portion, which slopes downward from the outside of the furnace to the inside of the furnace, and a fan-shaped pulverized coal blowing nozzle having an upward pulverized coal blowing opening at its tip is installed in this through hole. A smelting reduction furnace characterized in that a pulverized coal injection lance for gas reforming is inserted into the furnace so that it can move forward and backward. [Claim 2] A pulverized coal injection lance for gas reforming, which is inserted into a through hole provided in the furnace wall so as to be able to move forward and backward into the furnace, is rotatable around its axis. Claim 1
The described melting reduction furnace.