Hot air double-circulation drying system for vertical mill equipment and circulation quantity control method

Abstract

The invention belongs to the technical field of matching systems of vertical mill equipment, and provides a hot air double-circulation drying system for vertical mill equipment and a circulation volume control method. The hot air double-circulation drying system comprises a hot blast stove, an air outlet of the hot blast stove is communicated with an air inlet of a vertical mill through an air collecting box, and an air outlet of the vertical mill is communicated with an air inlet of a negative pressure fan; an air outlet of the negative pressure fan is communicated with an exhaust pipeline; one end of the first circulation control pipe fitting communicates with the interior of the exhaust pipeline through the side wall of the exhaust pipeline, and the other end of the first circulation control pipe fitting communicates with an air inlet of the hot blast stove; and one end of the second circulation control pipe fitting communicates with the interior of the exhaust pipeline through the side wall of the exhaust pipeline, and the other end of the second circulation control pipe fitting communicates with the interior of the air collecting box. The utilization rate of circulating hot air can be increased, and meanwhile normal operation of the vertical mill cannot be affected.

Description

Technical Field

[0001] The invention belongs to the technical field of supporting systems for vertical mill equipment, and in particular relates to a hot air double-circulation drying system for vertical mill equipment and a circulation volume control method. Background Art

[0002] The vertical mill system is an efficient powder processing equipment integrating grinding, sorting and drying, among which the drying subsystem is an important part of the production process. The system consists of hot air furnace, negative pressure fan, wind box, circulating air duct and other structures. The efficient operation of the system is directly related to the consumption of natural gas and product quality.

[0003] The main components of the gas discharged from the hot air circulation system are carbon dioxide, water vapor and a small amount of oxygen. Through the detection and calculation of the circulating air volume of the existing system, it can be known that the current circulating air utilization rate is generally between 50% and 60%. Therefore, considering how to improve the utilization rate of circulating air is an important means to achieve energy conservation and environmental protection.

[0004] In the industry, the common method to improve the utilization rate of circulating hot air is to increase the diameter of the circulating air duct. However, after long-term testing and use, it was found that this method can only increase the hot air circulation utilization rate to 70%, and it is easy to cause the inlet temperature to be low, affecting the grinding, powder selection and drying efficiency of the vertical mill. Summary of the invention

[0005] The purpose of the present invention is to provide a hot air double circulation drying system for vertical mill equipment to solve the above problems and achieve the purpose of improving the utilization rate of circulating hot air while not affecting the normal operation of the vertical mill.

[0006] To achieve the above object, the present invention provides the following solution: a hot air double circulation drying system for a vertical mill, comprising:

[0007] A hot blast furnace, wherein the air outlet of the hot blast furnace is connected to the air inlet of the vertical mill through a wind collecting box, the air outlet of the vertical mill is connected to the air inlet of the negative pressure fan, and the air outlet of the negative pressure fan is connected to an exhaust duct;

[0008] a first circulation control pipe, one end of which is connected to the interior of the exhaust duct through the side wall of the exhaust duct, and the other end of which is connected to the air inlet of the hot blast furnace;

[0009] A second circulation control pipe fitting, one end of which is connected to the interior of the exhaust duct through the side wall of the exhaust duct, and the other end of which is connected to the interior of the wind collecting box.

[0010] Preferably, the first circulation control pipe fitting includes a first circulation pipeline, the air inlet end of the first circulation pipeline passes through the side wall of the exhaust duct and is connected to the interior of the exhaust duct, the air inlet of the hot air furnace is connected to a manifold, the air outlet end of the first circulation pipeline is connected to the manifold, and the end of the first circulation pipeline close to the hot air furnace is connected to a first air valve.

[0011] Preferably, the second circulation control pipe fitting includes a second circulation pipeline, the air inlet end of the second circulation pipeline passes through the side wall of the exhaust duct and is connected to the interior of the exhaust duct, the air outlet end of the second circulation pipeline is connected to the interior of the wind collecting box, and the end of the second circulation pipeline close to the wind collecting box is connected to a second air valve.

[0012] Preferably, the air inlet end of the first circulation pipeline is located above the air inlet end of the second circulation pipeline.

[0013] Preferably, the distance between the air inlet end of the first circulation pipeline and the air inlet end of the second circulation pipeline is 1.5 meters.

[0014] Preferably, the outer side of the first circulation pipeline is wrapped with a thermal insulation layer.

[0015] Preferably, a dust collector is connected between the air outlet of the vertical mill and the air inlet of the negative pressure fan.

[0016] Preferably, pressure sensors are respectively provided in the hot blast furnace, the vertical mill and the dust collector.

[0017] A method for controlling the circulation volume of a hot air double circulation drying system for a vertical mill, comprising the following steps:

[0018] Detect negative pressure value in hot air furnace and vertical mill;

[0019] The openings of the first air valve and the second air valve are controlled according to the detected negative pressure value, and the negative pressure values ​​in the hot blast furnace and the vertical mill are maintained stable by controlling the hot air circulation amount.

[0020] Preferably, the opening of the first air valve is controlled between 30% and 40%, and the opening of the second air valve is controlled between 80% and 90%.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects: the main function of the hot air furnace is to provide a heat source for the drying system; the main function of the wind collector is to mix the hot air discharged from the hot air furnace with the hot air returned by the second circulation control pipe fitting, and then introduce them into the vertical mill together; the main function of the negative pressure fan is to create a negative pressure environment in the drying system, so that the hot air can flow through the hot air furnace, the wind collector and the vertical mill in sequence; the main function of the first circulation control pipe fitting is to reintroduce part of the gas discharged into the exhaust duct into the air inlet of the hot air furnace, and enter the hot air furnace to mix with the high-temperature hot air in the furnace; the main function of the second circulation control pipe fitting is to reintroduce part of the gas discharged into the exhaust duct into the wind collector box, so that it can be mixed with the gas discharged from the hot air furnace in the wind collector box. On the whole, the present invention achieves further improvement in the utilization rate of circulating hot air by setting two groups of circulation pipes and controlling part of the gas in the exhaust duct to flow back into the hot air furnace and the wind collecting box respectively. At the same time, the control of the gas flux by the first circulation control pipe and the second circulation control pipe can avoid affecting the normal operation of the vertical mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a connection schematic diagram of the drying system of the present invention;

[0024] Among them, 1. hot air furnace; 2. wind box; 3. vertical mill; 4. dust collector; 5. negative pressure fan; 6. exhaust duct; 7. first circulation pipeline; 8. second circulation pipeline; 9. first air valve; 10. second air valve. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Reference Figure 1 The present invention provides a hot air double circulation drying system for a vertical mill, comprising:

[0028] A hot blast furnace 1, the air outlet of the hot blast furnace 1 is connected to the air inlet of the vertical mill 3 through the wind collecting box 2, the air outlet of the vertical mill 3 is connected to the air inlet of the negative pressure fan 5, and the air outlet of the negative pressure fan 5 is connected to the exhaust duct 6;

[0029] A first circulation control pipe, one end of which is connected to the interior of the exhaust duct 6 through the side wall of the exhaust duct 6, and the other end of which is connected to the air inlet of the hot blast furnace 1;

[0030] The second circulation control pipe fitting has one end connected to the interior of the exhaust duct 6 through the side wall of the exhaust duct 6 , and the other end connected to the interior of the wind collecting box 2 .

[0031] The main function of the hot air furnace 1 is to provide a heat source for the drying system; the main function of the wind box 2 is to mix the hot air discharged from the hot air furnace 1 with the hot air returned from the second circulation control pipe, and then introduce them into the vertical mill 3 together; the main function of the negative pressure fan 5 is to create a negative pressure environment in the drying system, so that the hot air can flow through the hot air furnace 1, the wind box 2 and the vertical mill 3 in sequence; the main function of the first circulation control pipe is to reintroduce part of the gas discharged into the exhaust duct 6 into the air inlet of the hot air furnace 1, and enter the hot air furnace 1 to mix with the high-temperature hot air in the furnace; the main function of the second circulation control pipe is to reintroduce part of the gas discharged into the exhaust duct 6 into the wind box 2, so that it is mixed with the gas discharged from the hot air furnace 1 in the wind box 2. On the whole, the present invention achieves further improvement in the utilization rate of circulating hot air by setting two groups of circulation pipes and controlling part of the gas in the exhaust duct to flow back into the hot air furnace and the wind collecting box respectively. At the same time, the control of the gas flux by the first circulation control pipe and the second circulation control pipe can avoid affecting the normal operation of the vertical mill.

[0032] To further optimize the solution, the first circulation control pipe fitting includes a first circulation pipeline 7, the air inlet end of the first circulation pipeline 7 passes through the side wall of the exhaust duct 6 and is connected to the interior of the exhaust duct 6, the air inlet of the hot air furnace 1 is connected to the manifold, the air outlet end of the first circulation pipeline 7 is connected to the manifold, and the end of the first circulation pipeline 7 close to the hot air furnace 1 is connected to the first air valve 9.

[0033] like Figure 1As shown, the first circulation pipeline 7 uses a DN800 spiral welded pipe. The operation of the negative pressure fan 5 puts the vertical mill 3, the wind box 2 and the hot blast furnace 1 in a negative pressure environment. After the hot air discharged from the negative pressure fan 5 enters the exhaust duct 6, since the exhaust duct 6 is connected to the atmosphere, the negative pressure at the air inlet of the hot blast furnace 1 will draw part of the hot air back into the hot blast furnace 1 through the first circulation pipeline 7, so that the refluxed hot air is mixed with the high-temperature hot air in the furnace and enters the wind box 2 by negative pressure. The main function of the first air valve 9 is to control the amount of gas entering the hot blast furnace 1 from the first circulation pipeline 7 by adjusting the opening size.

[0034] A further optimized solution is that the second circulation control pipe fitting includes a second circulation pipeline 8, the air inlet end of the second circulation pipeline 8 passes through the side wall of the exhaust duct 6 and is connected with the interior of the exhaust duct 6, the air outlet end of the second circulation pipeline 8 is connected with the interior of the wind collecting box 2, and the end of the second circulation pipeline 8 close to the wind collecting box 2 is connected with a second air valve 10.

[0035] like Figure 1 As shown, after the hot air discharged from the negative pressure fan 5 enters the exhaust duct 6, since the exhaust duct 6 is connected to the atmosphere, the wind box 2 is in a negative pressure environment. Therefore, the negative pressure in the wind box 2 will draw part of the hot air back into the wind box 2 through the second circulation pipeline 8, so that it is mixed with the high-temperature hot air discharged from the hot blast furnace 1 in the wind box 2, and finally sent to the vertical mill 3 by negative pressure to dry the material in the vertical mill 3. The main function of the second air valve 10 is to control the amount of gas entering the wind box 2 from the second circulation pipeline 8 by adjusting the opening size.

[0036] According to a further optimized solution, the air inlet end of the first circulation pipeline 7 is located above the air inlet end of the second circulation pipeline 8 .

[0037] According to a further optimization scheme, the distance between the air inlet end of the first circulation pipeline 7 and the air inlet end of the second circulation pipeline 8 is 1.5 meters.

[0038] As a further optimization solution, the outer side of the first circulation pipeline 7 is wrapped with a heat-insulating layer (not shown in the figure).

[0039] The main function of the thermal insulation layer is to reduce the heat loss of the hot air in the first circulation pipeline 7 during the flow process.

[0040] To further optimize the solution, a dust collector 4 is connected between the air outlet of the vertical mill 3 and the air inlet of the negative pressure fan 5.

[0041] To further optimize the solution, pressure sensors (not shown in the figure) are respectively provided in the hot blast furnace 1, the vertical mill 3 and the dust collector 4.

[0042] like Figure 1As shown, the main function of the pressure sensors in the hot blast furnace 1, the vertical mill 3 and the dust collector 4 is to monitor the negative pressure values ​​in the hot blast furnace 1, the vertical mill 3 and the dust collector 4 respectively.

[0043] A further optimized solution also includes a control unit, and the first air valve 9, the second air valve 10 and the pressure sensors in the hot air furnace 1, the vertical mill 3 and the dust collector 4 are electrically connected to the control unit respectively.

[0044] A method for controlling the circulation volume of a hot air double circulation drying system for a vertical mill, comprising the following steps:

[0045] Detect the negative pressure value in the hot air furnace 1 and the vertical mill 3;

[0046] The negative pressure values ​​in the hot blast furnace 1, the vertical mill 3 and the dust collector 4 are monitored respectively by the pressure sensors in the hot blast furnace 1, the vertical mill 3 and the dust collector 4, so that the on-site personnel can know the pressure value and abnormal changes in each device at any time through the control unit.

[0047] The openings of the first air valve 9 and the second air valve 10 are controlled according to the detected negative pressure value, and the negative pressure values ​​in the hot blast furnace 1 and the vertical mill 3 are maintained stable by controlling the hot air circulation amount.

[0048] When the pressure sensor detects abnormal pressure in the system, the opening of the first air valve 9 and the second air valve 10 can be adjusted by the control unit, and the amount of hot air reflux in the first circulation pipeline 7 and the second circulation pipeline 8 can be controlled to restore the system negative pressure value to a normal range, so that the hot blast furnace 1 and the vertical mill 3 can maintain stable operation.

[0049] According to a further optimization scheme, the opening of the first air valve 9 is controlled between 30% and 40%, and the opening of the second air valve 10 is controlled between 80% and 90%.

[0050] like Figure 1 As shown, since the opening of the second air valve 10 is controlled within a relatively small range, it is possible to avoid excessive return hot air flow that would affect the normal combustion of the hot blast furnace 1.

[0051] Embodiment 2:

[0052] After the drying system in Example 1 is applied to the mixed grinding process of various solid waste raw materials with vertical mill equipment as the core, the hot air utilization rate of the entire system reaches 75%-80%. Compared with the traditional vertical mill drying system, the average natural gas consumption per ton of product is reduced from 15 cubic meters / ton to 13 cubic meters / ton, which saves costs and significantly reduces the use of natural gas. At the same time, the drying system can operate stably and will not cause the air volume balance of the circulating air system to be disturbed.

[0053] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0054] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A hot air double circulation drying system for vertical mill equipment, It is characterized in that include: A hot air furnace (1), wherein the air outlet of the hot air furnace (1) is connected to the air inlet of a vertical mill (3) through an air collecting box (2), the air outlet of the vertical mill (3) is connected to the air inlet of a negative pressure fan (5), and the air outlet of the negative pressure fan (5) is connected to an exhaust duct (6); a first circulation control pipe, one end of which is in communication with the interior of the exhaust duct (6) through the side wall of the exhaust duct (6), and the other end of which is in communication with the air inlet of the hot blast furnace (1); A second circulation control pipe fitting, one end of which is connected to the interior of the exhaust duct (6) through the side wall of the exhaust duct (6), and the other end of which is connected to the interior of the wind collecting box (2).

2. A hot air double circulation drying system for vertical mill equipment according to claim 1, Features: The first circulation control pipe comprises a first circulation pipeline (7), the air inlet end of the first circulation pipeline (7) passes through the side wall of the exhaust duct (6) and is connected to the interior of the exhaust duct (6), the air inlet of the hot air furnace (1) is connected to a manifold, the air outlet end of the first circulation pipeline (7) is connected to the manifold, and one end of the first circulation pipeline (7) close to the hot air furnace (1) is connected to a first air valve (9).

3. A hot air double circulation drying system for vertical mill equipment according to claim 2, Features: The second circulation control pipe comprises a second circulation pipeline (8), the air inlet end of the second circulation pipeline (8) passes through the side wall of the exhaust duct (6) and is connected to the interior of the exhaust duct (6), the air outlet end of the second circulation pipeline (8) is connected to the interior of the wind collecting box (2), and one end of the second circulation pipeline (8) close to the wind collecting box (2) is connected to a second air valve (10).

4. A hot air double circulation drying system for vertical mill equipment according to claim 3, Features: The air inlet end of the first circulation pipeline (7) is located above the air inlet end of the second circulation pipeline (8).

5. A hot air double circulation drying system for vertical mill equipment according to claim 4, Features: The distance between the air inlet end of the first circulation pipeline (7) and the air inlet end of the second circulation pipeline (8) is 1.5 meters.

6. A hot air double circulation drying system for vertical mill equipment according to claim 2, Features: The outer side of the first circulation pipeline (7) is wrapped with a thermal insulation layer.

7. A hot air double circulation drying system for vertical mill equipment according to claim 1, Features: A dust collector (4) is connected between the air outlet of the vertical mill (3) and the air inlet of the negative pressure fan (5).

8. A hot air double circulation drying system for vertical mill equipment according to claim 7, Features: Pressure sensors are respectively arranged in the hot blast furnace (1), the vertical mill (3) and the dust collector (4).

9. A method for controlling the circulation volume of a hot air double circulation drying system for a vertical mill, based on the hot air double circulation drying system for a vertical mill as claimed in claim 3, It is characterized in that the steps include: Detecting negative pressure values ​​in the hot air furnace (1) and the vertical mill (3); The openings of the first air valve (9) and the second air valve (10) are controlled according to the detected negative pressure value, and the negative pressure value in the hot air furnace (1) and the vertical mill (3) is maintained stable by controlling the hot air circulation volume.

10. A method for controlling the circulation volume of a hot air double circulation drying system for a vertical mill according to claim 9, Features: The opening degree of the first air valve (9) is controlled between 30% and 40%, and the opening degree of the second air valve (10) is controlled between 80% and 90%.

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