Kiln body air supply system of iron ore direct reduction rotary kiln

Abstract

The utility model provides a kiln body air supply system of an iron ore direct reduction rotary kiln, a plurality of air supply systems are arranged on the kiln back of the rotary kiln, each air supply system is composed of a kiln back fan, an air distribution ring pipe and an air ejection pipe, 2-3 kiln back fans are evenly arranged on the middle section of the kiln body in the kiln length direction, and the air ejection pipe is connected with the kiln back fan. 5-6 air distribution ring pipes are uniformly arranged on an air distribution pipeline of each kiln back fan in the kiln length direction, a plurality of air ejection pipes are uniformly arranged on the inner walls of the air distribution ring pipes in the direction close to the kiln back in the circumferential direction, one ends of the air ejection pipes are communicated with the air distribution ring pipes, and the other ends of the air ejection pipes extend into the rotary kiln; and the end part of the air ejection pipe is provided with an ejection opening and a protective cap, and the length of the air ejection pipe extending into the rotary kiln is about 20% of the diameter of the kiln body. The air supply uniformity of the rotary kiln in the length direction of the rotary kiln is improved, material heat transfer is enhanced, the influence of an air injection pipe on pea coal injection is reduced, liquid phase generation of iron ore in the reduction process is reduced, and the ring forming problem of the rotary kiln is prevented.

Description

Technical Field

[0001] The utility model belongs to the technical field of metallurgy and mineral engineering, and particularly relates to a kiln body air supply system for a direct reduction rotary kiln of iron ore. Background Art

[0002] In a direct reduction rotary kiln of iron ore, after a mixture of ore and coal is added from the feeding end of the rotary kiln, the mixed material exchanges heat with the countercurrent high-temperature flue gas during the process of flowing towards the discharging end. While recovering the heat of the high-temperature flue gas, the temperature of the iron ore continuously rises after being dried. When the temperature of the iron ore rises above 800 °C, the iron ore begins to be reduced. During the reduction process of the iron ore, a large amount of metallurgical gas continuously escapes from the inside of the material layer. This part of the metallurgical gas can be used as fuel. When the metallurgical gas is mixed with air, combustion occurs, thereby supplying heat to the inside of the kiln. When the iron ore travels to the discharging end position inside the kiln, the reduction process of the iron ore ends. In order to supply heat along the length direction of the rotary kiln, it is necessary to blow in combustion-supporting air at different positions along the length direction of the front section and the middle section of the kiln body of the rotary kiln, so that a large amount of metallurgical gas escaping from the inside of the material layer burns at different positions inside the kiln, and the iron ore is reasonably heated inside the kiln.

[0003] Figure 1 It is a structural diagram of the air supply for a traditional direct reduction rotary kiln of iron ore. In the direct reduction rotary kiln of iron ore, the air supply structure along the length direction of the kiln body is as follows: (1) Front section of the kiln body: By arranging a burner and a granular coal lance at the discharging end, air is blown into the kiln from the burner and the granular coal lance. At the same time, air is inhaled into the kiln from the furnace door and the feeding port at the discharging end. After the air burns the metallurgical gas, it supplies heat to the front end of the kiln body. (2) Middle section of the kiln body: By arranging a plurality of air injection pipes along the length direction on the kiln back of the middle section of the kiln body, the air injection pipes are composed of regulating valves, air distribution pipes, air main pipes, and kiln back fans. The inlet of each air injection pipe is connected to the regulating valve outside the kiln body. The jet outlet of the air injection pipe is located at the center position inside the kiln, and the air jet direction is parallel to the center line of the kiln body and jets towards the kiln tail direction. Each kiln back fan can supply air to one or more air injection pipes. When 1 kiln back fan supplies air to multiple air injection pipes, the combustion-supporting air blown out from the kiln back fan is supplied into the air distribution pipe through the air main pipe, and then the air is distributed to each air injection pipe through the air distribution pipe, and finally the air is sprayed into the kiln from the jet outlet. (3) Rear section of the kiln body: Generally, no heat supply is carried out in the rear section of the kiln body. Its function is to exchange heat between the high-temperature flue gas flowing from the middle section of the kiln body and the low-temperature material, so that while recovering the heat of the high-temperature flue gas, the material inside the kiln can be heated to a relatively high temperature.

[0004] In the above air supply structure of the rotary kiln body, the air supply volume in the middle section of the kiln body accounts for 60 - 70% of the total air supply volume. The main problems existing in this part of the air supply are as follows: (1) The air supply volume is mainly concentrated in the central part of the kiln, resulting in a concentrated high-temperature area in the central part of the kiln. During normal production of the rotary kiln, the problem of kiln body ring formation is likely to occur. (2) The flame in the high-temperature section of the rotary kiln cannot fill the furnace chamber, easily generating a cold air layer between the flame and the furnace charge, affecting the radiative heat transfer from the flame to the material. At the same time, a high-temperature layer is easily formed between the flame and the furnace top. The heating of the furnace top by the high-temperature flame is also likely to cause the problem of kiln body ring formation. (3) The number of air ejection pipes in the middle section of the kiln body is small, and local high temperatures are likely to occur inside the kiln body, causing liquid phase formation on the surface of iron ore and affecting the progress of reduction. (4) The ejection ports of the air ejection pipes are located in the central part of the kiln body. When the granular coal ejected by the granular coal spray gun moves along the central part of the kiln body towards the kiln tail direction, the granular coal is easily collided with the air blow pipes, resulting in a large amount of granular coal falling at the position of the air ejection pipes. Local high temperatures are easily generated at the position of the air ejection pipes during the combustion of granular coal. Utility Model Content

[0005] The utility model provides an air supply system for the kiln body of a direct reduction rotary kiln for iron ore, aiming to optimize the existing air supply system and air supply process of the rotary kiln to reduce the problems of easy ring formation and uneven temperature distribution of the rotary kiln.

[0006] For this reason, the utility model adopts the following technical solutions:

[0007] An air supply system for the kiln body of a direct reduction rotary kiln for iron ore, with multiple air supply systems arranged on the kiln back of the rotary kiln. Each air supply system consists of a kiln back fan, an air distribution ring pipe, and an air ejection pipe; the air distribution ring pipe is annularly sleeved outside the rotary kiln and is concentric with the rotary kiln, and the air distribution ring pipes are arranged at intervals; a plurality of air ejection pipes are connected to the air distribution ring pipe along the circumferential direction. One end of the air ejection pipe is communicated with the air distribution ring pipe, and the other end penetrates into the interior of the rotary kiln. The air ejection pipes are radially distributed; the head end of the air ejection pipe is provided with an ejection port and a protective cap, and the length of the air ejection pipe extending into the rotary kiln is 10% - 30% of the kiln body diameter;

[0008] The air blown in from the kiln back fan is transported through a pipeline to each air distribution ring pipe. Each air distribution ring pipe then distributes the air to each air ejection pipe, and each air ejection pipe finally transports the air into the rotary kiln and sprays it into the kiln along the ejection port.

[0009] Further, the protective cap is fixed at the front end of the air ejection pipe, the ejection port is located between the front end of the air ejection pipe and the protective cap, and the ejection port is circular, so that the air in the air ejection pipe is ejected along the circular direction of the ejection port.

[0010] Further, the outer shape of the protective cap is an "umbrella-shaped" structure.

[0011] Furthermore, the air ejection pipe is made of heat-resistant steel. A "Y"-shaped stainless steel anchoring claw is welded on the outer wall of the air ejection pipe, and a refractory castable with a thickness of 50 - 80 mm is cast on the outer wall, and the "Y"-shaped stainless steel anchoring claw is wrapped by the refractory castable material.

[0012] The beneficial effects of the utility model are as follows:

[0013] (1) By arranging a plurality of air supply systems for decentralized air supply on the kiln back in the middle section of the rotary kiln body of the utility model, and supplying air through burners and granular coal spray guns in the front section of the rotary kiln body, the metallurgical gas produced by the iron ore along the kiln length direction in the rotary kiln can be burned in a decentralized manner at different positions in the kiln, avoiding the emergence of high-temperature zones in the kiln, solving the generation of liquid phase in the iron ore reduction process, and further solving the problem of ring formation in the rotary kiln production.

[0014] (2) By implementing the air supply system of the direct reduction rotary kiln for iron ore of the utility model, the problem that the granular coal ejected by the granular coal spray gun is prone to collide with the air ejection pipe during the movement from the central part of the kiln body towards the kiln tail direction, resulting in an excessive falling amount of granular coal at the position of the air ejection pipe and local high temperature being easily generated at the position of the air ejection pipe is solved.

[0015] (3) The flame in the rotary kiln of the utility model fills the furnace chamber, and there is no cold air layer between the flame and the furnace charge, improving the radiant heat transfer amount from the flame to the material.

[0016] (4) The utility model is provided with refractory materials on the outer surface of the air ejection pipe, solving the problem of short service life of the air ejection pipe during operation at high temperatures. Description of the Drawings

[0017] Figure 1 is the air supply system diagram of the traditional direct reduction rotary kiln for iron ore;

[0018] Figure 2 is the air supply system diagram of the direct reduction rotary kiln for iron ore of the utility model;

[0019] Figure 3 is the sectional view (A - A) of the direct reduction rotary kiln for iron ore of the utility model;

[0020] Figure 4 is the partial enlarged view of the air ejection pipe of the air supply system of the direct reduction rotary kiln for iron ore;

[0021] 1 - kiln back fan, 2 - air main pipe, 3 - air distribution ring pipe, 4 - regulating valve, 5 - air ejection pipe, 6 - ejection port, 7 - protective cap, 8 - anchoring claw, 9 - refractory castable. Detailed Embodiment

[0022] The present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0023] As Figure 1 shown, the air supply system for the kiln body of a direct reduction rotary kiln for iron ore of the present utility model is as follows:

[0024] (1) The air supply system for the kiln body of the rotary kiln mainly consists of a kiln back fan 1, an air main pipe 2, an air distribution pipe, an air distribution ring pipe 3, an air ejection pipe 5, an ejection port 6, a protective cap 7, refractory materials, and anchoring claws 8; an air supply system is provided on the kiln back of the rotary kiln, and the air supply system consists of a kiln back fan 1, an air main pipe 2, an air distribution pipe, an air distribution ring pipe 3, an air ejection pipe 5, an ejection port 6, and a protective cap 7. Along the length direction of the middle section of the kiln body, 2 kiln back fans 1 are evenly arranged, and along the length direction of the air distribution pipe of each kiln back fan 1, 5 air distribution ring pipes 3 are evenly arranged. The air distribution ring pipe 3 is sleeved outside the kiln body of the rotary kiln and fixed on the kiln back. Along the circumferential direction near the kiln back on the inner wall of the air distribution ring pipe 3, 8 air ejection pipes 5 are evenly arranged. One end of the air ejection pipe 5 is communicated with the air distribution ring pipe 3, and the other end extends into the rotary kiln, and an ejection port 6 and a protective cap 7 are provided at its end. The length of the air ejection pipe 5 extending into the rotary kiln is about 20% of the kiln body diameter.

[0025] (2) The air blown in from the kiln back fan 1 is transported to the air distribution pipe through the air main pipe 2, and the air is distributed to each air distribution ring pipe 3 by the air distribution pipe. Each air distribution ring pipe 3 then distributes the air to each air ejection pipe 5, and each air ejection pipe 5 finally transports the air into the rotary kiln and sprays it into the kiln along the ejection port 6.

[0026] (3) A protective cap 7 is provided at the front end of the air ejection pipe 5. The protective cap 7 is fixed at the front end of the air ejection pipe 5. The ejection port 6 is located between the front end of the air ejection pipe 5 and the protective cap 7. The ejection port 6 is in a circular ring shape, which can make the air in the air ejection pipe 5 spray out along the circular ring direction of the ejection port 6.

[0027] (4) The protective cap 7 is set in an "umbrella-shaped" structure. The adjustment of the air volume along the length direction of the middle section of the rotary kiln body is adjusted by adjusting the air supply volume of each kiln back fan 1. The material of the air ejection pipe 5 is selected as heat-resistant steel, and a "Y"-shaped stainless steel anchoring claw 8 is welded on the outer wall, and then a layer of refractory castable 9 with a thickness of 50 - 80 mm is cast on the outer wall of the air ejection pipe 5.

[0028] (5) The metallurgical gas produced by the reduction reaction of iron ore in the present utility model escapes from the inside of the material layer and enters the space inside the kiln. At this time, air is blown into the kiln through the air supply system. After the metallurgical gas is mixed with air, combustion occurs, thereby heating the middle section of the kiln body. In the front section of the kiln body, the metallurgical gas is mixed with the air blown through the burner and the granular coal lance and then burns, thereby heating the front section of the kiln body.

[0029] (6) By controlling the air volume of the air ejection pipes 5 at different positions in the middle section of the kiln body and the air volume of the granular coal lance and the burner in the front section of the kiln body, the combustion of the metallurgical gas generated in the kiln at different positions in the kiln is achieved.

Claims

1. A kiln air supply system for an iron ore direct reduction rotary kiln, characterized in that: A plurality of air supply systems are arranged on the kiln back of the rotary kiln, each of which is composed of a kiln back fan (1), an air distribution ring pipe (3), and an air ejection pipe (5); the air distribution ring pipe (3) is annularly sleeved outside the rotary kiln and is concentric with the rotary kiln, and the air distribution ring pipes (3) are arranged at intervals; a plurality of air ejection pipes (5) are connected to the upper edge of the air distribution ring pipe (3) in an annular direction, one end of the air ejection pipe (5) is connected to the air distribution ring pipe (3), and the other end penetrates into the interior of the rotary kiln, and the air ejection pipes (5) are radially distributed; a ejection port (6) and a protective cap (7) are arranged at the head end of the air ejection pipe (5), and the length of the air ejection pipe (5) extending into the rotary kiln is 10%-30% of the diameter of the kiln body; The air blown in from the kiln back fan (1) is transported to each air distribution ring pipe (3) through a pipeline. Each air distribution ring pipe (3) then distributes the air to each air ejection pipe (5). Each air ejection pipe (5) finally transports the air into the rotary kiln and then ejects the air into the kiln along the ejection port (6).

2. The kiln air supply system of the iron ore direct reduction rotary kiln according to claim 1, characterized in that: The protective cap (7) is fixed to the front end of the air ejection pipe (5), the ejection port (6) is located between the front end of the air ejection pipe (5) and the protective cap (7), and the ejection port (6) is in a circular ring shape, so that the air in the air ejection pipe (5) is ejected along the ring direction of the ejection port (6).

3. The kiln air supply system of the iron ore direct reduction rotary kiln according to claim 2, characterized in that: The protective cap (7) has an "umbrella-shaped" structure.

4. The kiln air supply system of the iron ore direct reduction rotary kiln according to claim 1, characterized in that: The material of the air ejection pipe (5) is heat-resistant steel. A "Y"-shaped stainless steel anchor claw (8) is welded on the outer wall of the air ejection pipe (5). A layer of refractory castable (9) with a thickness of 50-80 mm is poured on the outer wall. The refractory castable (9) wraps the "Y"-shaped stainless steel anchor claw (8).

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