Precision Control and Conditioning Furnace for Roasting Rotary Kiln

Abstract

The present invention is a precision control and conditioning furnace for a roasting rotary kiln, which comprises a furnace body. One end of the furnace body is equipped with a burner, and the burner is provided with a gas port and a primary air inlet. The other end is provided with a smoke injection port, which is installed facing the roasting rotary kiln. One end of the furnace body near the burner is provided with a partition board, and a cavity is formed between the partition board and the furnace body shell. One side of the cavity is provided with a secondary air inlet. A plurality of outer direct current air ducts are arranged along the circumferential direction inside the furnace wall, and the outer direct current air ducts are arranged axially. The inlets of all the outer direct current air ducts are communicated with the cavity, and the outlets extend to the smoke injection port. The present invention conditions the flue gas, realizes increasing the flue gas flow rate while reducing the flue gas temperature, and avoids overburning of the materials, and is especially applicable to a direct heating rotary kiln.

Description

Technical Field

[0001] The present invention relates to the field of roasting kilns, and more particularly to a precision control and conditioning furnace for a roasting rotary kiln. Background Art

[0002] In a traditional rotary kiln roasting system, a high-temperature flame spray gun is used to roast the materials in the rotary kiln. However, when precise control of the final temperature of the roasted materials is required, there are significant problems. The heat transfer of the materials in the rotary kiln mainly consists of three parts: radiation, conduction, and convection. However, for different positions from the kiln head to the kiln tail in the rotary kiln, the intensity of each type of heat transfer is quite different. At the kiln head position, radiation and conduction are mainly involved. The temperature of the high-temperature flame reaches above 1400 °C, and the radiation intensity of the flame on the materials is large. At the same time, the flame heats up the refractory at the kiln head, and the refractory conducts heat to the materials for secondary heating. These two types of heat transfer dominate at the kiln head. At the middle position of the kiln, radiation and convection are the main heat transfer methods, and their intensity further decreases. At the kiln tail, the materials are mainly heated by convection.

[0003] During the heating and roasting process of the materials, many chemical reactions occur. Different chemical reactions have strict requirements for temperature and reaction time. When the temperature is too high, harmful reactions will occur, resulting in over-roasted materials. In a traditional roasting system, if the temperature gradient between each stage of chemical reactions is large, the roasting control is relatively easy. If the temperature gradient between each stage of chemical reactions is small, very high requirements are imposed on the temperature control accuracy in the rotary kiln. During the production process, in order to meet the production target, the system load needs to be increased. In order to meet the product quality standard, precise temperature control is required, not just the point temperature control of the kiln head and the kiln tail, but accurate adjustment of the temperature distribution throughout the rotary kiln. Because the heat absorption methods at the kiln head and the kiln tail are different, when the system load is increased, there will be irreconcilable contradictions between production and quality. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems existing in the above-mentioned existing roasting rotary kiln, and provide a precision control and conditioning furnace for a roasting rotary kiln, which can avoid over-roasting of the materials by controlling the heating temperature of the materials while increasing the production, and ensure the quality of the products.

[0005] The specific solution of the present invention is as follows: A precision control and conditioning furnace for a roasting rotary kiln includes a furnace body. One end of the furnace body is equipped with a burner, and the burner is provided with a gas port and a primary air inlet. The other end is provided with a smoke outlet, and the smoke outlet is installed facing the roasting rotary kiln. One end of the furnace body near the burner is provided with a partition board, and a cavity is formed between the partition board and the furnace body shell. One side of the cavity is provided with a secondary air inlet. A plurality of outer direct current air ducts are arranged circumferentially along the furnace wall, and the outer direct current air ducts are arranged axially. The inlets of all the outer direct current air ducts are communicated with the cavity, and the outlets extend to the smoke outlet.

[0006] Furthermore, a number of inner swirl air ducts are arranged circumferentially along the furnace wall. Each inner swirl air duct is composed of a straight air duct and an inclined air duct connected together. The straight air duct is arranged along the axial direction of the furnace body. The inlet of the straight air duct is communicated with the cavity. An angle of 100°-150° is provided between the inclined air duct and the axis, and an angle of 100°-150° is provided between the inclined air duct and the radial line. The outlet of the inclined air duct is located in the latter half of the inner wall of the furnace body.

[0007] Furthermore, a number of inner direct current air ducts are provided on the partition plate. The length of the inner direct current air duct is equal to the thickness of the partition plate. The inlet of the inner direct current air duct is communicated with the cavity, and the outlet is communicated with the furnace chamber.

[0008] Furthermore, the outer wall of the furnace body is of a sandwich structure. An outer swirl air duct is arranged in the sandwich. An air blowing port is provided on the outer wall of the furnace body. The air blowing port is communicated with the inlet of the outer swirl air duct. An outlet of the outer swirl air duct is provided on the end face of the furnace body. The outlet of the outer swirl air duct is communicated with the primary air inlet through a pipeline.

[0009] Furthermore, a spiral partition plate is arranged in the outer swirl air duct.

[0010] Furthermore, the outer swirl air duct diffuses first and then converges from the inlet to the outlet.

[0011] The present invention has the following beneficial effects: 1. By adopting a tempering furnace, the direct injection flame heating method is changed to a flue gas heating method. The high-temperature flame is controlled in the tempering furnace and will not directly perform thermal radiation heating on the materials in the rotary kiln; 2. The amount and temperature of the flue gas generated by the tempering furnace can be adjusted reversely. When increasing the production capacity, the gas flow rate and the flow rate of the primary air can be increased to increase the flue gas volume. At the same time, the flow rate of the secondary air is increased. The secondary air has a cooling effect on the flue gas, so as to realize increasing the flue gas flow rate while reducing the flue gas temperature, so that the flue gas temperature does not increase with the increase of the flow rate, and overburning of the materials is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic structural diagram of the present invention;

[0013] Figure 2 is Figure 1 the left view of

[0014] Figure 3 is a schematic diagram of the flow directions of the primary air, secondary air and flue gas of the present invention;

[0015] Figure 4 is a simulation diagram of the temperature distribution of the flue gas supplied to the roasting rotary kiln by the present invention;

[0016] In the figure: 1, air tuyere; 2, secondary air inlet; 3, gas inlet; 4, smoke outlet; 5, regulating valve; 6, primary air inlet; 7, outer swirling air outlet; 8, outer shell; 9, inner shell; 10, refractory material; 11, spiral partition; 12, outer swirling air duct; 13, inner direct current air duct; 14, outer direct current air duct; 15, inner swirling air duct; 16, burner; 17, outer direct current air; 18, inner direct current air; 19, inner swirling air; 20, secondary air; 21, primary air; 22, preheated air; 23, flue gas. Detailed implementation manners

[0017] Embodiment 1

[0018] See Figures 1-3, this embodiment is a precision control and conditioning furnace for a roasting rotary kiln, including a furnace body. One end of the furnace body is equipped with a burner 16. The burner 16 is provided with a gas port and a primary air inlet 6. A regulating valve 5 is provided at the primary air inlet 6 to control the flow rate of the primary air 21. The other end is provided with a smoke spraying port 4, and the smoke spraying port 4 is installed facing the roasting rotary kiln. Near the burner 16 at one end inside the furnace body, there is a partition board. A cavity is formed between the partition board and the furnace body shell 8. One side of the cavity is provided with a secondary air inlet 2. Along the circumferential direction of the furnace wall, there are several outer direct current air ducts 14. The outer direct current air ducts 14 are arranged axially in the refractory material 10. The inlets of all the outer direct current air ducts 14 are communicated with the cavity, and the outlets extend to the smoke spraying port 4. After the secondary air 20 enters the cavity from the secondary air inlet 2, it flows through the outer direct current air ducts 14 to the smoke spraying port 4 and mixes with the high-temperature flue gas 23 to cool the high-temperature flue gas 23. Further, along the circumferential direction of the furnace wall, there are several inner swirl air ducts 15. Each inner swirl air duct 15 is composed of a straight air duct and an inclined air duct connected. The straight air duct is arranged along the axial direction of the furnace body. The inlet of the straight air duct is communicated with the cavity. There is an included angle of 100° between the inclined air duct and the axis, and there is an included angle of 100° between the inclined air duct and the radial line. The outlet of the inclined air duct is located in the second half of the inner wall of the furnace body. Each inner swirl air 19 rotates and flows in the same direction after entering the furnace. The beneficial effect of such a design is that after the inner swirl air 19 enters the furnace, on the one hand, it cools the inner wall of the furnace, and on the other hand, it strengthens the combustion intensity of the flame, improves the burnout rate of the gas, enhances the combustion effect, and reduces the generation of carbon monoxide. Further, several inner direct current air ducts 13 are provided on the partition board. The length of the inner direct current air ducts 13 is equal to the thickness of the partition board. The inlets of the inner direct current air ducts 13 are communicated with the cavity, and the outlets are communicated with the furnace chamber. The beneficial effects are as follows: After the secondary air 20 enters the cavity, a part of it directly enters the front end of the furnace chamber through each inner direct current air duct 13 to perform primary conditioning on the flue gas 23, a part of it enters the rear end of the furnace chamber through each inner swirl air duct 15 to perform secondary conditioning on the flue gas 23, and a part of it reaches the smoke spraying port 4 through each outer direct current air duct 14 to perform tertiary conditioning on the flue gas 23 outside the furnace. The temperature of the flue gas 23 is precisely controlled through three times of conditioning. Further, the outer wall of the furnace body is composed of an outer shell 8 and an inner shell 9. There is a hollow sandwich structure between the outer shell 8 and the inner shell 9. An outer swirl air duct 12 is provided in the sandwich. An air blowing port 1 is provided on the outer wall of the furnace body. The air blowing port 1 is communicated with the inlet of the outer swirl air duct 12. The outlet of the outer swirl air duct 12 is provided on the end face of the furnace body. The outlet of the outer swirl air duct 12 is communicated with the primary air inlet 6 through a pipeline. Further, a spiral partition board 11 is provided in the outer swirl air duct 12. Further, the outer swirl air duct 12 diffuses first and then converges from the inlet to the outlet direction.Its beneficial effects are as follows: When the primary air 21 passes through the outer swirl air duct 12, it absorbs the heat of the furnace body. On the one hand, it cools down the furnace body, and on the other hand, it has a preheating effect. The preheated primary air 21 enters the primary air inlet 6 through the pipeline from the outer swirl air outlet 7, improving the combustion effect.

[0019] See Figure 4 , which is the flue gas temperature distribution diagram simulated by computer simulation software. It can be seen from the figure that the flue gas temperature distribution in the entire roasting rotary kiln is uniform and the temperature gradient change is small. Embodiment 2 The structure of this embodiment is basically the same as that of Embodiment 1, except that there is an included angle of 150° between the inclined air duct and the axis, and an included angle of 150° between the inclined air duct and the radial line. Embodiment 3 The structure of this embodiment is basically the same as that of Embodiment 1, except that there is an included angle of 120° between the inclined air duct and the axis, and an included angle of 120° between the inclined air duct and the radial line.

Claims

1. Precision control and conditioning furnace for roasting rotary kiln, comprising a furnace body, a burner is installed at one end of the furnace body, the burner is provided with a gas port and a primary air inlet, and a smoke injection port is provided at the other end, the smoke injection port is installed facing the roasting rotary kiln, and its characteristics are as follows: One end of the furnace body near the burner is provided with a partition board. A cavity is formed between the partition board and the furnace body shell. A secondary air inlet is arranged on one side of the cavity. A plurality of outer direct current air ducts are arranged along the circumferential direction inside the furnace wall. The outer direct current air ducts are arranged axially. The inlets of all the outer direct current air ducts are communicated with the cavity, and the outlets extend to the smoke spraying ports. A plurality of inner swirl air ducts are arranged along the circumferential direction inside the furnace wall. Each inner swirl air duct is composed of a straight air duct and an inclined air duct connected. The straight air duct is arranged along the axial direction of the furnace body. The inlet of the straight air duct is communicated with the cavity. An included angle of 100°-150° is provided between the inclined air duct and the axis, and an included angle of 100°-150° is provided between the inclined air duct and the radial line. The outlet of the inclined air duct is located in the latter half part of the inner wall of the furnace body.

2. The fine control and conditioning furnace for the roasting rotary kiln according to claim 1, characterized in that: A plurality of inner direct current air ducts are arranged on the partition board. The length of the inner direct current air duct is equal to the thickness of the partition board. The inlet of the inner direct current air duct is communicated with the cavity, and the outlet is communicated with the furnace chamber.

3. The fine control and conditioning furnace for a roasting rotary kiln according to claim 1, characterized in that: The outer wall of the furnace body is of a sandwich structure. An outer swirl air duct is arranged inside the sandwich. An air blowing port is arranged on the outer wall of the furnace body. The air blowing port is communicated with the inlet of the outer swirl air duct. An outlet of the outer swirl air duct is arranged on the end face of the furnace body. The outlet of the outer swirl air duct is communicated with the primary air inlet through a pipeline.

4. The fine control and conditioning furnace for a roasting rotary kiln according to claim 3, characterized in that: A spiral partition board is arranged inside the outer swirl air duct.

5. The fine control and conditioning furnace for a roasting rotary kiln according to claim 3, characterized in that: The outer swirl air duct diffuses first and then converges from the inlet to the outlet direction.

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