Heat supply system of belt type roasting machine

Abstract

The utility model provides a belt type roasting machine heat supply system which comprises hot air supply systems, fuel supply systems, combustion chambers and a gas mixing chamber, the combustion chambers are arranged on the two sides of the gas mixing chamber and communicated with the gas mixing chamber, and the fuel supply system and the hot air supply system are arranged on each combustion chamber; the hot air supply system comprises a header pipe and a branch pipe, one end of the branch pipe communicates with the header pipe, the other end of the branch pipe communicates with the combustion chamber, the combustion chamber is a cylindrical cavity, and the branch pipe and the vertical middle section of the combustion chamber are arranged in a staggered mode so that hot air flow output by the branch pipe can form spiral vortex in the combustion chamber; the fuel supply system comprises burners, the burners are arranged on the combustion chamber, and the axes of the burners and the axis of the combustion chamber are arranged in a staggered mode so that fuel sprayed out of the burners can form spiral vortexes in the combustion chamber. The branch pipes and the axis of the combustion chamber are arranged in a staggered mode, so that hot air forms vortex in the combustion chamber, and flame edge burning is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of metal smelting equipment, and particularly relates to a heat supply system for a grate-kiln roasting machine. Background Art

[0002] Pellets are an important raw material for blast furnace ironmaking, accounting for about 20 - 40% of the total charge into the blast furnace. With the improvement of blast furnace production technology, the proportion of pellets in blast furnace raw materials is further increasing. Among the existing pellet production equipment, the grate-kiln roasting machine has become the mainstream technical equipment in the current pellet production field and the first choice for new pellet production projects due to its advantages such as high thermal efficiency, small floor area, and good product quality. The heat supply system is the core and key component of the grate-kiln roasting machine, playing an important role in providing the required heat for the pellet roasting process. Therefore, the technical transformation and upgrading of the existing grate-kiln roasting machine and its heat supply system have become a hot topic of concern in the industry.

[0003] The existing heat supply system of the grate-kiln roasting machine mainly adopts an arrangement form in which the combustion chamber and the secondary air duct are vertically arranged, and the fuel flow and the high-temperature secondary air flow are perpendicular to each other. Such an arrangement form has advantages such as a compact structure and stable flame combustion, and has become the standard design of the existing grate-kiln heat supply system. However, such a structural form has the defect of flame burning at the edge. Due to the large amount of vertically downward secondary air, the horizontal fuel flow is pushed towards the bottom of the combustion chamber, causing the flame in the combustion chamber to deviate downward. Seriously, it will cause the flame to scour the inner wall of the bottom of the combustion chamber, commonly known as flame burning at the edge, resulting in serious erosion of the refractory material at the bottom of the combustion chamber affected by the flame scouring and affecting the service life of the equipment. The specific structure can be seen in Figure 1 .

[0004] In summary, there is an urgent need for a heat supply system for a grate-kiln roasting machine to solve or at least partially solve the problems existing in the prior art. Content of the Utility Model

[0005] The purpose of the utility model is to provide a heat supply system for a grate-kiln roasting machine, aiming to solve the problem that due to the large amount of vertically downward secondary air, the horizontal fuel flow is pushed towards the bottom of the combustion chamber, causing the flame in the combustion chamber to deviate downward and resulting in flame burning at the edge. The specific technical solution is as follows:

[0006] A belt roasting machine heating system includes a hot air supply system, a fuel supply system, a combustion chamber and an air mixing chamber. Combustion chambers are arranged on both sides of the air mixing chamber, and the two combustion chambers on both sides are respectively connected to the air mixing chamber. A fuel supply system and a hot air supply system are arranged on each combustion chamber; the hot air supply system includes a main pipe and branch pipes, and multiple branch pipes are arranged at intervals along the extension direction of the main pipe. One end of the branch pipe is connected to the main pipe, and the other end of the branch pipe is connected to the combustion chamber. The combustion chamber is a cylindrical chamber, and the branch pipe and the vertical mid-section of the combustion chamber are staggered; the fuel supply system includes a burner, which is arranged on the combustion chamber and connected to the inside of the combustion chamber.

[0007] Furthermore, the burner nozzle and the vertical mid-section of the combustion chamber are staggered.

[0008] Furthermore, the branch pipe is arranged tangentially along the combustion chamber.

[0009] Furthermore, a plurality of branch pipes are arranged along the axis of the combustion chamber, one end of each branch pipe is connected to the main pipe, and the other end of each branch pipe is connected to the combustion chamber.

[0010] Furthermore, the axis of the burner forms an angle β with a straight line passing through the center of the combustion chamber and the intersection point of the burner and the combustion chamber, and the angle β is between 15 degrees and 60 degrees.

[0011] Furthermore, the angle β is between 30 degrees and 45 degrees.

[0012] Furthermore, two burners are arranged, and the two burners form a group, and the burners in the same group are distributed symmetrically along the center of the combustion chamber.

[0013] Furthermore, the burners are arranged in multiple groups, and the multiple groups of burners are arranged in sequence along the axis direction of the combustion chamber.

[0014] Furthermore, the branch pipes are arranged tangentially along the combustion chamber, and multiple branch pipes are arranged, and the multiple branch pipes are arranged along the axis of the combustion chamber. One end of each branch pipe is connected to the main pipe, and the other end of each branch pipe is connected to the combustion chamber. Each branch pipe is arranged one-to-one with each group of burners.

[0015] Furthermore, the speed of the fuel injected into the burner is controlled between 45 meters per second and 120 meters per second.

[0016] Furthermore, the speed of the fuel injected into the burner is controlled between 60 meters per second and 80 meters per second.

[0017] The application of the technical solution of the utility model has the following beneficial effects:

[0018] Hot air enters the branch pipe from the main pipe and is sprayed into the combustion chamber from the branch pipe. Since the axis of the main pipe is staggered with that of the combustion chamber, the hot air ejected from the branch pipe will generate a rotational motion around the inner wall of the combustion chamber during the process of moving along the inner wall of the combustion chamber, forming a spiral eddy current with the movement towards the mixing chamber; the fuel is ejected through the burner. Since the axis of the burner is staggered with that of the combustion chamber, the hot air ejected from the burner will generate a rotational motion around the inside of the combustion chamber during the process of moving along the inner wall of the combustion chamber, and the direction of the rotational motion is the same as that of the hot air. During the rotation process, the heat and the fuel are fully mixed and evenly distributed in the combustion chamber during combustion, so that the flame in the combustion chamber gathers in the middle of the combustion chamber, and it is not easy to cause the situation of the combustion chamber flame burning the edge. Since the heat and the fuel are more evenly mixed in the combustion chamber, the temperature distribution of the flue gas after combustion is also more uniform.

[0019] In addition to the purposes, features and advantages described above, the present utility model has other purposes, features and advantages. The following will refer to Figures 1-3 for a further detailed description of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings forming a part of this application are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0021] Figure 1 is a drawing of the background art of the present utility model;

[0022] Figure 2 is a schematic diagram of the overall structure of a belt grate firing system of the present utility model;

[0023] Figure 3 is a schematic diagram of the internal structure on the side of a belt grate firing system of the present utility model.

[0024] Wherein, 1, hot air supply system; 11, main pipe; 12, branch pipe; 2, fuel supply system; 21, burner; 22, included angle β; 3, combustion chamber; 4, mixing chamber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] To facilitate understanding of the present utility model, the present utility model will be described more comprehensively below, and preferred embodiments of the present utility model are given. However, the present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present utility model more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] Example:

[0028] See also Figures 2-3 The present embodiment provides a belt roaster heating system, including a hot air supply system 1, a fuel supply system 2, a combustion chamber 3 and a gas mixing chamber 4. The combustion chamber 3 is arranged on both sides of the gas mixing chamber 4. The two combustion chambers 3 on both sides are respectively connected to the gas mixing chamber 4. Each combustion chamber 3 is arranged with a fuel supply system 2 and a hot air supply system 1; the hot air supply system 1 includes a main pipe 11 and branch pipes 12. The multiple branch pipes 12 are arranged at intervals along the extension direction of the main pipe 11. One end of the branch pipe 12 is connected to the main pipe 11. The other end of the branch pipe 12 is connected to the combustion chamber 3, and the combustion chamber 3 is a cylindrical chamber. The branch pipe 12 is staggered with the vertical mid-section of the combustion chamber 3 so that the hot air flow output by the branch pipe 12 forms a spiral vortex in the combustion chamber 3; the fuel supply system 2 includes a burner 21, which is arranged on the combustion chamber 3 and is connected to the inside of the combustion chamber 3. The axis of the burner 21 is staggered with the vertical mid-section of the combustion chamber 3 so that the fuel ejected from the burner 21 forms a spiral vortex in the combustion chamber 3.

[0029] Specifically, the combustion chamber 3 and the mixing chamber 4 are arranged horizontally, with a combustion chamber 3 arranged on each side of the mixing chamber 4. One end of the combustion chamber 3 is closed, and the other end of the combustion chamber 3 is connected to the mixing chamber 4, so that the hot air from the main pipe flows into the branch pipe 12 and can directly pass through the combustion chamber 3 into the mixing chamber 4.

[0030] It can be understood that the hot air enters the branch pipe 12 from the main pipe and is sprayed into the combustion chamber 3 from the branch pipe 12. Since the main pipe and the axis of the combustion chamber 3 are staggered, the hot air sprayed from the branch pipe 12 will generate a rotational motion around the inner wall of the combustion chamber 3 during the process of moving along the inner wall of the combustion chamber 3, forming a spiral vortex with the movement toward the mixing chamber; the fuel is sprayed through the burner 21. Since the burner 21 and the axis of the combustion chamber 3 are staggered, the hot air sprayed from the burner 21 will generate a rotational motion around the combustion chamber 3 during the process of moving along the inner wall of the combustion chamber 3, and the direction of the rotational motion is The hot air rotates in the same direction as the hot air. During the rotation process, the heat is fully mixed with the fuel and evenly distributed within the combustion chamber 3 during combustion, causing the flame within the combustion chamber 3 to concentrate in the center of the combustion chamber 3, making it less likely for the flame to burn along the edges of the combustion chamber 3. Because the heat and fuel are mixed more evenly within the combustion chamber 3, the temperature distribution of the flue gas after combustion is also more uniform. Furthermore, during the combustion process, the flame is prevented from concentrating on the inner wall of the combustion chamber 3, minimizing the occurrence of localized high temperatures, reducing the production of combustion pollutants such as NOx, and reducing air pollution. It should be noted that the subscript "x" represents a number, and "NOx" represents nitrogen oxides.

[0031] Furthermore, the branch pipe 12 is arranged tangentially along the inner wall of the combustion chamber 3. It is understood that when the branch pipe 12 is arranged tangentially along the inner wall of the combustion chamber 3, the heat ejected from the branch pipe 12 moves in a circular motion along the inner wall of the combustion chamber 3 and is transported toward the gas mixing chamber 4, thereby forming a spiral vortex that flows toward the gas mixing chamber 4. During the flow process, the direction of the hot air continuously changes as the position moves, thereby preventing combustion from being biased toward a certain position in the combustion chamber 3 and achieving more uniform combustion.

[0032] Furthermore, a plurality of branch pipes 12 are arranged, and the plurality of branch pipes 12 are arranged along the axial direction of the combustion chamber 3. One end of each branch pipe 12 is communicated with the main pipe 11, and the other end of each branch pipe 12 is communicated with the combustion chamber 3. Specifically, in this embodiment, taking three branch pipes 12 as an example, the three branch pipes 12 are arranged at equal intervals along the axial direction of the combustion chamber 3. The hot air conveyed from the main pipe 11 is respectively ejected from the three branch pipes 12. After being ejected from the three branch pipes 12, the ejected hot air is more easily mixed uniformly with the fuel ejected from the burner 21. Moreover, the three branch pipes 12 form a three-stage mixing. After the three-stage mixing, the hot air and the fuel are more fully mixed, and the temperature of the flue gas after combustion is more uniform and stable, which is beneficial to the smooth and stable progress of combustion. Of course, in other embodiments of the present application, there may also be two branch pipes 12, four branch pipes 12, five branch pipes 12 or more branch pipes 12. Relatively speaking, the more branch pipes 12 there are, the more uniform the mixing is, but the complexity and manufacturing cost also increase accordingly. The fuel and the hot air form an overall swirling flow centered on the central axis of the combustion chamber 3 and mix with each other. The fuel and the hot air burn near the central axis of the combustion chamber 3. The generated high-temperature flue gas enters the mixing chamber 4 and then is discharged from the bottom of the mixing chamber 4, providing heat for the pellet ore on the trolley at the bottom of the mixing chamber 4 to be burned, and the generated waste gas is discharged from the bottom of the trolley. The temperature of the hot air is about 900 degrees Celsius, and the temperature of the high-temperature flue gas is about 1300 degrees Celsius.

[0033] Furthermore, the axis of the burner 21 forms an angle β22 with the straight line passing through the center of the combustion chamber 3 and the intersection point of the burner 21 and the combustion chamber 3. The angle β22 is between 15 degrees and 60 degrees. Specifically, the fuel ejected from the burner 21 will rotate along the inner wall of the combustion chamber 3 to form a spiral eddy current, and the direction of this spiral eddy current is the same as the direction of the spiral eddy current of the hot air. The two spiral eddy currents of the hot air and the fuel are fully mixed during the movement. It should be noted that through research and experiments, when the angle is between 15 degrees and 60 degrees, a better mixing effect is achieved. Of course, this numerical range also includes 15 degrees and 60 degrees. It should be noted that above this range, the flame is likely to burn the edge; below this range, the flame is overly concentrated at the position of the central axis of the combustion chamber 3, resulting in a high peak temperature of the flame and an increase in the generation amount of pollutants such as NOx. Among them, when the angle β22 is between 30 degrees and 45 degrees, a better mixing and combustion effect is achieved. Of course, this numerical range also includes 30 degrees and 45 degrees.

[0034] Furthermore, two burners 21 are arranged in the same plane, and the two burners 21 form a group. The burners 21 within the same group are symmetrically distributed about the center of the combustion chamber 3. It can be understood that by arranging two burners 21 in the same plane, the fuel is ejected from the two burners 21 simultaneously, and the fuel ejected from the two burners 21 moves in a coaxial spiral manner along the inner wall of the combustion chamber 3, reducing the fuel ejected from a single burner 21 and ejecting it from different positions. When the fuel is mixed with the hot air, the uniformity and sufficiency of the mixing are further improved.

[0035] Furthermore, multiple groups of burners 21 are arranged, and the multiple groups of burners 21 are arranged in sequence along the axial direction of the combustion chamber 3. It can be understood that by ejecting fuel from multiple groups of burners 21, the fuel is ejected from different positions of the combustion chamber 3, and the ejected fuel burns at different positions of the combustion chamber 3, preventing the aggregation of flames, thereby making the temperature of the flue gas after combustion more uniform and the combustion more sufficient.

[0036] Furthermore, the branch pipes 12 are arranged tangentially to the combustion chamber 3. A plurality of branch pipes 12 are arranged, and the plurality of branch pipes 12 are arranged along the axial direction of the combustion chamber 3. One end of each branch pipe 12 is communicated with the main pipe 11, and the other end of each branch pipe 12 is communicated with the combustion chamber 3. Each branch pipe 12 is arranged in one-to-one correspondence with each group of burners 21. It can be understood that by arranging each group of burners 21 in one-to-one correspondence with each branch pipe 12, the high-temperature gas ejected from the branch pipe 12 and the fuel ejected from the burner 21 can be mixed quickly and sufficiently, making the combustion of the mixed gas more sufficient. It should be noted that each of the branch pipes 12 and the corresponding group of burners 21 form a primary combustion, and the multiple branch pipes 12 and their corresponding burners 21 form multiple-stage combustion in sequence.

[0037] It should be noted that through research and experiments, it is found that when the injection speed of the fuel into the burner 21 is controlled between 45 m / s and 120 m / s, the mixing effect of the fuel and the hot air is better. Below this range, the mixing effect between the fuel and the combustion-supporting air is poor, the combustion efficiency is low, and the peak temperature of the flame is high, resulting in a large amount of NOx generation; above this range, flashback is likely to occur, resulting in unstable combustion. Among them, when the injection speed of the fuel into the burner 21 is controlled between 60 m / s and 80 m / s, the mixing effect of the fuel and the hot air is better.

[0038] The working principle of applying the present utility model is as follows: When working, hot air is introduced into the main pipe. The hot air flows from the main pipe to each branch pipe 12 respectively, and then flows from each branch pipe 12 into the combustion chamber 3, forming a spiral eddy current in the combustion chamber 3 and flowing towards the mixing chamber 4; Fuel is introduced into the combustion chamber 3 through the burner 21. The fuel is sprayed into the combustion chamber 3 from the burner 21 and mixed with the hot air ejected from the branch pipes 12. The fuel flows along the wall of the combustion chamber 3, and forms a spiral eddy current in the combustion chamber 3 and flows towards the mixing chamber 4. The fuel and the hot air are fully mixed and burned in the combustion chamber 3. Because the fuel and the hot air flow in a spiral mixing manner during the mixing process, the flame is concentrated in the middle of the combustion chamber 3 during the combustion process, and the flame generated by the fuel combustion will not be concentrated on the side wall of the combustion chamber 3. Therefore, the situation of flame burning the edge is avoided as much as possible. In addition, during the mixing process, multi-stage mixing combustion is formed through multiple branch pipes 12 and multiple groups of nozzles, making the mixing more sufficient, the combustion more stable and sufficient, and the temperature of the flue gas after combustion more uniform.

[0039] The beneficial effects of the present utility model are as follows:

[0040] 1. The fuel and the hot air enter tangentially along the combustion chamber 3. The fuel and the air form an overall rotational flow along the central axis of the combustion chamber 3. The fuel and the air are mixed and burned near the central axis of the combustion chamber 3. Therefore, the flame is concentrated near the central axis of the combustion chamber 3 and far from the inner wall of the combustion chamber 3. Therefore, the erosion of the flame by the hot air and the phenomenon of flame burning the edge are avoided.

[0041] 2. The fuel and the hot air enter tangentially along the combustion chamber 3, and an overall rotational flow along the central axis will be formed in the combustion area. The generation of this overall rotational flow will effectively enhance the mixing and heat transfer process between the unreacted gas and the reaction product, thereby greatly increasing the uniformity of the temperature of the flue gas flowing out of the tail of the combustion chamber 3 and improving the quality of pellet roasting.

[0042] 3. On the one hand, staged combustion of the fuel can effectively reduce the peak temperature of the flame. On the other hand, due to the use of tangential swirling to introduce the combustion-supporting hot air and the fuel, the mixing of the hot air and the fuel is improved, and the combustion reaction area is expanded, further reducing the peak temperature during the combustion process. Therefore, the emissions of pollutants such as NOx generated during the combustion process can be effectively reduced. It should be noted that the hot air described in the text is actually air heated to about 900 degrees Celsius.

[0043] The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A belt roaster heating system, characterized by: It includes a hot air supply system (1), a fuel supply system (2), a combustion chamber (3) and an air mixing chamber (4), The combustion chambers (3) are arranged on both sides of the gas mixing chamber (4), and the two combustion chambers (3) are respectively connected to the gas mixing chamber (4). The fuel supply system (2) and the hot air supply system (1) are arranged on each combustion chamber (3). The hot air supply system (1) comprises a main pipe (11) and a branch pipe (12), wherein a plurality of the branch pipes (12) are arranged at intervals along the extension direction of the main pipe (11), one end of the branch pipe (12) is connected to the main pipe (11), and the other end of the branch pipe (12) is connected to the combustion chamber (3), wherein the combustion chamber (3) is a cylindrical chamber, and the branch pipe (12) and the vertical mid-section of the combustion chamber (3) are staggered. The fuel supply system (2) includes a burner (21), which is arranged on the combustion chamber (3) and communicates with the interior of the combustion chamber (3).

2. A belt roaster heating system according to claim 1, characterized in that: The burner (21) and the vertical mid-section of the combustion chamber (3) are staggered.

3. The belt roaster heating system according to claim 1, characterized in that: The branch pipe (12) is arranged tangentially along the combustion chamber (3).

4. A belt roaster heating system according to claim 3, characterized in that: A plurality of branch pipes (12) are arranged, and the plurality of branch pipes (12) are arranged along the axial direction of the combustion chamber (3); one end of each branch pipe (12) is connected to the main pipe (11), and the other end of each branch pipe (12) is connected to the combustion chamber (3).

5. A belt roaster heating system according to any one of claims 1 to 4, characterized in that: The axis of the burner (21) forms an angle β (22) with a straight line passing through the center of the combustion chamber (3) and the intersection point of the burner (21) and the combustion chamber (3), and the angle β (22) is between 15 degrees and 60 degrees.

6. A belt roaster heating system according to claim 5, characterized in that: Two burners (21) are arranged, and the two burners (21) form a group. The burners (21) in the same group are distributed symmetrically along the center of the combustion chamber (3).

7. A belt roaster heating system according to claim 6, characterized in that: The burners (21) are arranged in multiple groups, and the multiple groups of burners (21) are arranged in sequence along the axial direction of the combustion chamber (3).

8. The belt roaster heating system according to claim 7, characterized in that: The branch pipes (12) are arranged tangentially to the combustion chamber (3), a plurality of the branch pipes (12) are arranged, and the plurality of branch pipes (12) are arranged in the axial direction of the combustion chamber (3). One end of each branch pipe (12) is communicated with the main pipe (11), the other end of each branch pipe (12) is communicated with the combustion chamber (3), and each branch pipe (12) is arranged in one-to-one correspondence with each group of burners (21).

9. A heat supply system for a traveling grate roaster according to any one of claims 1-4, characterized in that: The speed of the fuel injected by the burner (21) is controlled between 45 meters per second and 120 meters per second.

10. A heat supply system for a traveling grate roaster according to claim 9, characterized in that: The speed of the fuel injected by the burner (21) is controlled between 60 meters per second and 80 meters per second.

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