Method for controlling pressure difference stability of roller type vertical mill

Abstract

The invention discloses a method for controlling the pressure difference of a roller type vertical mill to be stable. The method comprises the following steps: selecting raw materials with the storage time of more than or equal to 3 days and the water content of less than or equal to 10% as milling water granulated slag; the grinding temperature is 95-105 DEG C, and the pressure of a grinding roller is 10.5 Mpa. According to the method, the in-mill pressure difference is stably controlled to be 2800pa by virtue of mutual cooperation among various parameters by reasonably controlling the in-mill water granulated slag and feeding amount, the exhaust capacity of a main exhaust fan, the width of an air ring air regulating plate, the frequency of a powder concentrator, the out-mill temperature of a vertical mill system and the pressure of a grinding roller.

Description

Technical Field

[0001] The invention relates to the technical field of vertical mill production, and in particular to a method for controlling the pressure difference stability of a roller type vertical mill. Background Art

[0002] The pressure difference inside the roller mill is a key control indicator in the production of the vertical mill and one of the important parameters that reflects the material circulation load inside the mill. After the main induced draft fan provides the system negative pressure air volume, the resistance generated by the operation of the powder selector and the local ventilation resistance at the wind ring of the vertical mill, the sum of these two resistances constitutes the pressure difference of the mill. During the operation of the vertical mill, the stable pressure difference of the mill indicates that the raw materials entering the vertical mill and the finished products leaving the mill have reached a dynamic equilibrium state. Once there is a large fluctuation, it will affect the stable operation of the vertical mill, causing mill vibration and fluctuations in the quality of the micro powder product.

[0003] In order to achieve the goal of stable and high production of the mill, effectively save energy, extend the service life of the equipment, and increase the internal profits of our company, the pressure difference inside the mill needs to be controlled at about 2800pa. If the pressure difference is too high, on the one hand, it will cause the external circulation volume of the mill to increase, and more return materials will be returned. Over time, the dynamic balance of the internal circulation of the mill will be destroyed, causing a series of adverse reactions such as mill vibration; on the other hand, the dust on site is serious, which seriously causes environmental accidents. If the pressure difference of the mill is too small, the mill cannot reach the state of efficient operation, the circulating material in the mill will become less and less, and over time, the grinding disc material layer will be too thin, causing the mill to vibrate and stop. Therefore, determining a reasonable pressure difference inside the mill and strictly implementing the parameter requirements can achieve the best production efficiency and economic benefits of the vertical mill. After research, the present invention finds that the water slag entering the mill and the feed amount, the exhaust capacity of the main exhaust fan, the opening and direction of the nozzle ring, and the process parameters of the vertical mill system are important factors affecting the pressure difference inside the mill. Therefore, how to control the water slag entering the mill and the feed amount, the exhaust capacity of the main exhaust fan, the opening of the air ring air regulating plate, and the process parameters of the vertical mill system so that the pressure difference inside the mill can be stably controlled at 2800Pa is the current research direction. At present, there is no public research on how to control the water slag entering the mill and the feed amount, the exhaust capacity of the main exhaust fan, the opening of the air ring air regulating plate, and the process parameters of the vertical mill system to stabilize the pressure difference inside the mill at around 2800Pa. Summary of the invention

[0004] In view of the above-mentioned prior art, the purpose of the present invention is to provide a method for controlling the stable pressure difference of a roller vertical mill. The present invention reasonably controls the amount of water slag and material entering the mill, the exhaust capacity of the main exhaust fan, the width of the air ring regulating plate, the frequency of the powder selector, the outlet temperature of the vertical mill system and the grinding roller pressure, so that various parameters cooperate with each other to stably control the pressure difference in the mill at 2800pa.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The invention provides a method for controlling the pressure difference stability of a roller type vertical mill. The raw material with a storage time of ≥3 days and a moisture content of ≤10% is selected as the water slag entering the mill; the outlet temperature of the mill is 95-105°C, and the roller pressure is 10.5Mpa.

[0007] Preferably, the feeding amount of water slag into the mill is 100-105t / h.

[0008] Preferably, the storage time of the water slag entering the mill is 3-5 days. If the water slag is stored for too short a time, the grindability is poor, and the water content of the water slag is high, the gas consumed in the production process also increases, and the load of the main motor is large, and the power consumption also increases accordingly; if the water slag is stored for too long, the grindability is improved, but due to the characteristics of the water slag, it is easy to cause agglomeration. After it is put into production and use, the water content is low, which to a certain extent affects the formation of the mill disc material bed, causing the mill to run unsteadily.

[0009] Preferably, the moisture content of the water slag entering the mill is 7%-10%. If the moisture content of the raw material entering the mill is too low, the required hot air volume and hot air temperature are relatively low. After entering the mill, the hot air volume and hot air temperature are relatively high, resulting in a faster drying speed of the incoming material moisture, and the material cannot be effectively attached to the grinding disc of the mill for full grinding. The specific surface area quality cannot meet the screening of the powder selector, and the material is suspended in the mill to increase the resistance of the powder selector and cause the pressure difference of the mill to increase. This situation is easy to cause unstable air volume of the system, and in severe cases, the material collapses and stops vibrating, causing production stagnation and equipment damage.

[0010] If the moisture content of the raw material entering the mill is too high, the hot air volume and hot air temperature under the original mill operating conditions are low, and the water slag entering the mill cannot be dried out of the mill in time, so the water slag entering the mill is accumulated on the mill grinding wheel, the material layer becomes thicker, and the grinding efficiency of the vertical mill is reduced. At the same time, the destruction of the material layer causes the mill to vibrate, affecting the stable operation of the mill and the quality stability of the finished product.

[0011] Preferably, the particle size of the slag entering the mill is ≤5 cm.

[0012] Preferably, the frequency of the main exhaust fan is 33-35Hz, the frequency of the powder selector is 38-41Hz, and the exhaust volume is 275000-287000m 3 / h. Reasonable exhaust air volume can improve the operation efficiency and stability of the vertical mill.

[0013] Preferably, the width of the air ring air regulating plate is 50-150 mm, and the air flow direction is clockwise spiral ascending.

[0014] If the width of the air ring regulating plate is too narrow, the wind speed entering the mill will be faster, which will speed up the internal circulation speed of the vertical mill. Under the condition of water slag raw materials with good grindability, the pressure difference of the vertical mill will decrease significantly, and the load of the main motor of the vertical mill will increase. If the width of the air ring regulating plate is too wide, the external circulation volume of the vertical mill will increase, the pressure difference inside the mill will show a downward trend, and the load of the main motor of the vertical mill will decrease.

[0015] The direction of the wind ring determines the direction of the vertical mill airflow, which affects the amount of finished products after the water slag is ground in the powder classifier area. The airflow direction controlled by the present invention can maximize the powder selection amount in the powder classifier area.

[0016] Preferably, the vertical mill main motor current is controlled to be 160-190A.

[0017] Beneficial effects of the present invention:

[0018] The present invention reasonably controls various parameters such as the amount of water slag and material fed into the mill, the exhaust capacity of the main exhaust fan, the width of the air ring air regulating plate, the outlet temperature of the vertical mill system and the pressure of the grinding roller, so that the pressure difference in the mill is stably controlled at 2800pa, avoiding the vibration of the mill and the fluctuation of the quality of the micro-powder product caused by the fluctuation of the pressure difference in the mill, improving the stability of the vertical mill operation, and achieving the best production efficiency and economic benefits of the vertical mill. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0020] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0021] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0022] Embodiment 1:

[0023] A method for controlling the pressure difference of a roller mill: selecting raw materials with a storage time of 3 days and a moisture content of 10% as the water slag entering the mill, the particle size of the water slag entering the mill is ≤5cm, and the feeding amount of the water slag entering the mill is 100t / h; the frequency of the main exhaust fan is 33.5Hz, and the exhaust volume is 275000m 3 / h; the powder concentrator frequency is 41Hz, the width of the air ring air regulating plate is 50mm, and the air flow direction is clockwise spiral rising; the outlet temperature is 95℃, the grinding roller pressure is 10.5Mpa, the main motor current of the vertical mill is controlled to be 160A; the pressure difference inside the vertical mill is 2800pa.

[0024] Embodiment 2:

[0025] A method for controlling the pressure difference of a roller mill: selecting raw materials with a storage time of 4 days and a moisture content of 9% as the water slag entering the mill, the particle size of the water slag entering the mill is ≤5cm, and the feeding amount of the water slag entering the mill is 103t / h; the frequency of the main exhaust fan is 34.5Hz, and the exhaust volume is 283000m 3 / h; the powder concentrator frequency is 40Hz, the width of the air ring air regulating plate is 100mm, and the air flow direction is clockwise spiral rising; the outlet temperature is 105℃, the grinding roller pressure is 10.5Mpa, the main motor current of the vertical mill is controlled to be 190A; the pressure difference inside the vertical mill is 2800pa.

[0026] Embodiment 3:

[0027] A method for controlling the pressure difference of a roller mill: selecting raw materials with a storage time of 5 days and a moisture content of 7% as the water slag entering the mill, the particle size of the water slag entering the mill is ≤5cm, and the feeding amount of the water slag entering the mill is 105t / h; the frequency of the main exhaust fan is 35Hz, and the exhaust volume is 287000m 3 / h; the powder concentrator frequency is 38Hz, the width of the air ring air regulating plate is 150mm, and the air flow direction is clockwise spiral rising; the outlet temperature is 100℃, the grinding roller pressure is 10.5Mpa, the main motor current of the vertical mill is controlled to be 180A; the pressure difference inside the vertical mill is 2800pa.

[0028] Comparative Example 1:

[0029] A method for controlling the pressure difference of a roller mill: selecting raw materials with a storage time of 1 day and a moisture content of 15% as the water slag entering the mill, the particle size of the water slag entering the mill is ≤5cm, and the feeding amount of the water slag entering the mill is 95t / h; the frequency of the main exhaust fan is 34.5Hz, and the exhaust volume is 283000m 3 / h; the frequency of the powder selector is 42Hz, the width of the air ring air regulating plate is 50mm, and the air flow direction is clockwise spiral rising; the outlet temperature is 105℃, the grinding roller pressure is 10.5Mpa, the main motor current of the vertical mill is controlled to be 190A; the pressure difference inside the vertical mill is 2930pa.

[0030] Comparative Example 2: A method for controlling the pressure difference of a roller mill: Select raw materials with a storage time of 4 days and a moisture content of 9% as the water slag entering the mill, the particle size of the water slag entering the mill is ≤5cm, and the feeding amount of the water slag entering the mill is 103t / h; the frequency of the main exhaust fan is 36.5Hz, and the exhaust volume is 299300m 3 / h; the powder concentrator frequency is 41Hz, the width of the air ring air regulating plate is 100mm, and the air flow direction is clockwise spiral rising; the outlet temperature is 110℃, the grinding roller pressure is 15Mpa, the main motor current of the vertical mill is controlled to be 200A; the pressure difference inside the vertical mill is 2910pa.

[0031] It can be seen from Examples 1-3 that the pressure difference in the vertical mill can be stably controlled at 2800 Pa by the method of the present invention. It can be seen from Comparative Examples 1-2 that changing the parameters of the present invention will cause the pressure difference in the mill to be unable to be stably controlled at 2800 Pa. Therefore, the water slag and feed amount entering the mill, the exhaust capacity of the main exhaust fan, the width of the air ring air regulating plate, the outlet temperature of the vertical mill system and the grinding roller pressure are reasonably controlled so that the various parameters cooperate with each other to stably control the pressure difference in the mill at 2800 Pa. The various parameters cooperate with each other and are indispensable.

[0032] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for controlling the pressure difference stability of a roller mill, characterized in that: The raw materials with storage time ≥3 days and moisture ≤10% are selected as the water slag entering the mill; the outlet temperature is 95-105°C and the grinding roller pressure is 10.5Mpa.

2. The method according to claim 1, characterized in that: The feed rate of slag into the mill is 100-105t / h.

3. The method according to claim 1, characterized in that: The storage time of grinding slag is 3-5 days.

4. The method according to claim 1, characterized in that: The moisture content of the slag entering the mill is 7%-10%.

5. The method according to claim 1, characterized in that: The particle size of the slag entering the mill is ≤5cm.

6. The method according to claim 1, characterized in that: The frequency of the main exhaust fan is 33-35HZ, the frequency of the powder selector is 38-41Hz, and the exhaust volume is 275000-287000m 3 / h.

7. The method according to claim 1, characterized in that: The width of the wind ring air regulating plate is 50-150mm.

8. The method according to claim 1, characterized in that: Control the main motor current of the vertical mill to 160-190A.