Method for controlling stable operation of roller type vertical mill

Abstract

The invention discloses a method for controlling stable operation of a roller type vertical mill. The mill is stable and high in yield by controlling raw materials entering the mill, the thickness of a material layer, the grinding pressure, the air volume of a main induced draft fan of the vertical mill and the pressure difference in the mill. 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% for grinding; the grinding time is 0 to 48 hours, the grinding pressure is 9.5 to 10.5 Mpa, the grinding time is 48 to 56 hours, the grinding pressure is 10 to 11 Mpa, the grinding time is 56 to 64 hours, the grinding pressure is 10.5 to 11.5 Mpa, and the grinding pressure in the later stage of grinding is 10.7 to 11.7 Mpa; and the pressure difference in the mill is controlled to be 2500-3000 Pa. By reasonably controlling raw materials entering the mill, the thickness of a material layer, the grinding pressure, the air volume of a main induced draft fan of the vertical mill and the pressure difference in the mill, various parameters are mutually coordinated and matched to achieve the effect of stable and high yield of the vertical mill.

Description

Technical Field

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

[0002] Roller vertical mill is a new type of cement processing equipment. Compared with traditional ball mill, it has many important advantages, such as high grinding efficiency, simple process flow, small footprint, and integration of drying, grinding and powder selection. It is more and more widely used in new dry process cement and slag micro powder production lines. It is an ideal and effective grinding equipment for large-scale new dry process cement production lines. Nowadays, how to operate roller vertical mill in a refined manner, optimize process parameters, stabilize operation, increase output, reduce energy consumption, improve operation rate, and continuously improve economic benefits is the central issue of vertical mill maintenance and management.

[0003] Our factory currently has two 600,000 tons / year slag micro powder vertical mill production lines, with an annual output of 1.2 million tons of slag micro powder. The first phase of the vertical mill was put into production in 2015. Due to the short contact time with the new equipment and the inadequate understanding of the process, the vertical mill output was low and the equipment operation rate was low. Since the second phase was put into production in 2019, it has been found through research that the raw materials entering the mill, the thickness of the material layer, the grinding pressure, the air volume of the main induced draft fan of the vertical mill and the pressure difference inside the mill are important factors affecting the stable operation of the roller vertical mill. The stable operation of the roller vertical mill is the key to the stable and high production of the vertical mill.

[0004] Based on this, the present invention achieves the effect of stable and high production of the vertical mill by reasonably controlling parameters such as raw materials entering the mill, material layer thickness, grinding pressure, air volume of the vertical mill main induced draft fan and pressure difference inside the mill. Summary of the invention

[0005] In view of the above-mentioned prior art, the purpose of the present invention is to provide a method for controlling the stable operation of a roller vertical mill. The present invention reasonably controls the raw materials entering the mill, the thickness of the material layer, the grinding pressure, the air volume of the main induced draft fan of the vertical mill and the pressure difference inside the mill, so that various parameters cooperate with each other to achieve the effect of stable and high production of the vertical mill.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention provides a method for controlling the stable operation of a roller type vertical mill. The method can achieve stable and high production of the mill by controlling the raw materials entering the mill, the thickness of a material layer, the grinding pressure, the air volume of a main induced draft fan of the vertical mill and the pressure difference inside the mill. The raw materials entering the mill are selected to have a storage time of ≥3 days and a moisture content of ≤10%. When the grinding time is 0-48 hours, the grinding pressure is 9.5-10.5Mpa, when the grinding time is 48-56 hours, the grinding pressure is 10-11Mpa, when the grinding time is 56-64 hours, the grinding pressure is 10.5-11.5Mpa, and the grinding pressure in the later stage of grinding is 10.7-11.7Mpa. The pressure difference inside the mill is controlled to be 2500-3000Pa.

[0008] Preferably, the feed rate of raw materials into the mill is 103-105t / h.

[0009] Preferably, the material layer thickness is controlled by controlling the height of the retaining ring, and the height of the retaining ring is 24-26cm. The material layer thickness is related to the height of the retaining ring, and a suitable retaining ring height can improve the grinding efficiency of the vertical mill. If the retaining ring is too low, the material layer is too thin, resulting in direct contact between the grinding roller and the grinding disc, causing the mill to vibrate, which not only reduces the mill output but also causes great damage to the equipment; if the retaining ring is too high, the material layer is too thick, resulting in low grinding efficiency, and the load of the main motor of the vertical mill will also increase, which is also not conducive to improving product quality. The height of the retaining ring is 24-26cm, and the output of the mill and the equipment load can reach a matching state.

[0010] Preferably, the air volume of the main induced draft fan of the vertical mill is 280000-350000m 3 / h. The vertical mill mainly relies on the airflow generated by the main induced draft fan to drive the material circulation. By properly controlling the air volume, a good internal circulation can be formed, so that the material layer on the disc is appropriate and stable, and the grinding efficiency is high.

[0011] Preferably, the power of the main induced draft fan of the vertical mill is 1250KW, and the frequency of the main induced draft fan of the vertical mill is 35-43HZ.

[0012] Preferably, the current of the vertical mill main motor is 150-180A.

[0013] Preferably, the water slag entering the mill is stored for 3-5 days, and the moisture content of the water slag entering the mill is 7%-10%. If the water slag is stored for too short a time, the grindability is poor, the water content of the water slag is high, the gas consumed in the production process is increased, 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 moisture content is low, which to a certain extent affects the formation of the grinding disc material bed of the mill, causing the mill to run unsteadily. At this time, the temperature needs to be increased, and water is sprayed inside the mill to stabilize the material layer and the pressure difference inside the mill, resulting in unnecessary energy waste. If the moisture content of the raw material entering the mill is too low, the required hot air volume and hot air temperature will be lower. After entering the mill, the hot air volume and hot air temperature will be higher, resulting in a faster drying speed of the incoming material, which cannot effectively adhere to the grinding wheel of the mill for sufficient grinding. The specific surface area quality cannot meet the screening of the powder selector, and thus it will be suspended in the mill, increasing the resistance of the powder selector and causing the pressure difference of the mill to increase. This situation can easily lead to unstable air volume in the system. In severe cases, the material will collapse and vibrate to stop, causing production stagnation and equipment damage.

[0014] Since wind has a great influence on the operation of the vertical mill, the operation state of the vertical mill should be kept constant. If the pressure difference is too low, full-load production cannot be guaranteed, resulting in increased energy consumption; if the pressure difference is too high, it will be "full grinding", which will not only cause large vibration of the vertical mill and damage the equipment, but also increase the amount of slag discharged by the vertical mill, generate dust, and cause environmental pollution. The present invention reasonably controls the pressure difference in the mill so that the dynamic circulation of the material in the mill reaches the full-load state and the mill runs stably.

[0015] Beneficial effects of the present invention:

[0016] 1. Through reasonable control of the raw materials entering the mill, the thickness of the material layer, the grinding pressure, the air volume of the main induced draft fan of the vertical mill and the pressure difference inside the mill, the various parameters can be coordinated with each other to achieve the effect of stable and high production of the vertical mill.

[0017] 2. The vibration times of the roller vertical mill are significantly reduced through the method of the present invention, which effectively reduces the loss of equipment and extends the service life of the equipment; the proportion of process downtime rate decreases year by year, ensuring the output and quality of finished products, laying a solid foundation for market development; the stability of the vertical mill is gradually improved, the vibration times of the vertical mill are reduced from 24 times in 2020 to 4 times in 2023, and the process downtime rate is reduced from 0.65% in 2020 to 0.25% in 2023, achieving remarkable results. DETAILED DESCRIPTION

[0018] 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.

[0019] 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.

[0020] 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.

[0021] Example 1

[0022] A method for controlling the stable operation of a roller vertical mill: the raw materials entering the mill are selected to have a storage time of 3 days and a moisture content of 10%, and the feed rate of the raw materials entering the mill is 103 t / h; when the grinding time is 0-48h, the grinding pressure is 9.5-10.5Mpa, when the grinding time is 48-56h, the grinding pressure is 10-11Mpa, when the grinding time is 56-64h, the grinding pressure is 10.5-11.5Mpa, and the grinding pressure in the later stage of grinding is 10.7-11.7Mpa; the height of the retaining ring is 24-26cm; the pressure difference in the mill is controlled to be 2600-2800Pa; the power of the main induced draft fan of the vertical mill is 1250KW, and the air volume of the main induced draft fan of the vertical mill is 287000m 3 / h-310000m 3 / h, the frequency of the main induced draft fan of the vertical mill is 35-38HZ, and the current of the main motor of the vertical mill is 150-180A.

[0023] Example 2

[0024] A method for controlling the stable operation of a roller vertical mill: the raw materials entering the mill are selected to have a storage time of 5 days and a moisture content of 7%, and the feed rate of the raw materials entering the mill is 105t / h; when the grinding time is 0-48h, the grinding pressure is 9.5-10.5Mpa, when the grinding time is 48-56h, the grinding pressure is 10-11Mpa, when the grinding time is 56-64h, the grinding pressure is 10.5-11.5Mpa, and the grinding pressure in the later stage of grinding is 10.7-11.7Mpa; the height of the retaining ring is 24-26cm; the pressure difference in the mill is controlled to be 2600-2800Pa; the power of the main induced draft fan of the vertical mill is 1250KW, and the air volume of the main induced draft fan of the vertical mill is 310000m 3 / h-350000m 3 / h, the frequency of the main induced draft fan of the vertical mill is 38-43HZ, and the current of the main motor of the vertical mill is 160-180A.

[0025] Example 3

[0026] A method for controlling the stable operation of a roller vertical mill: the raw materials entering the mill are selected to have a storage time of 4 days and a moisture content of 8%, and the feed rate of the raw materials entering the mill is 104t / h; when the grinding time is 0-48h, the grinding pressure is 9.5-10.5Mpa, when the grinding time is 48-56h, the grinding pressure is 10-11Mpa, when the grinding time is 56-64h, the grinding pressure is 10.5-11.5Mpa, and the grinding pressure in the later stage of grinding is 10.7-11.7Mpa; the height of the retaining ring is 24-26cm; the pressure difference in the mill is controlled to be 2600-2900Pa; the power of the main induced draft fan of the vertical mill is 1250KW, and the air volume of the main induced draft fan of the vertical mill is 310000m 3 / h-335000m 3 / h, the frequency of the main induced draft fan of the vertical mill is 38-41HZ, and the current of the main motor of the vertical mill is 160-180A.

[0027] Example 4

[0028] A method for controlling the stable operation of a roller vertical mill: the raw materials entering the mill are selected to have a storage time of 4 days and a moisture content of 9%, and the feed rate of the raw materials entering the mill is 103 t / h; when the grinding time is 0-48h, the grinding pressure is 9.5-10.5Mpa, when the grinding time is 48-56h, the grinding pressure is 10-11Mpa, when the grinding time is 56-64h, the grinding pressure is 10.5-11.5Mpa, and the grinding pressure in the later stage of grinding is 10.7-11.7Mpa; the height of the retaining ring is 24-26cm; the pressure difference in the mill is controlled to be 2600-2850Pa; the power of the main induced draft fan of the vertical mill is 1250KW, and the air volume of the main induced draft fan of the vertical mill is 300000m 3 / h-328000m 3 / h, the frequency of the main induced draft fan of the vertical mill is 37-40HZ, and the current of the main motor of the vertical mill is 155-175A.

[0029] In 2023, the method of the above-mentioned embodiments 1-4 was applied. After the above-mentioned method was applied, the vibration times of the vertical mill were reduced from 24 times in 2020 to 4 times in 2023, and the process downtime rate was reduced from 0.65% in 2020 to 0.25% in 2023, and remarkable results were achieved. The vibration times of the roller vertical mill were significantly reduced, which effectively reduced the loss of the equipment and extended the service life of the equipment; the proportion of process downtime rate decreased year by year, which ensured the output and quality of the finished products and laid a solid foundation for market development. In summary, the method of the present invention continuously improves the stability of the vertical mill, and significantly reduces the process downtime rate, which not only increases the output per unit hour, but also extends the service life of the equipment through stable operation.

[0030] 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 stable operation of a roller mill, characterized in that: The mill can be made to produce high and stable output by controlling the raw materials entering the mill, the thickness of the material layer, the grinding pressure, the air volume of the main induced draft fan of the vertical mill and the pressure difference inside the mill; the raw materials entering the mill should be stored for ≥3 days and have a moisture content of ≤10%; When the grinding time is 0-48h, the grinding pressure is 9.5-10.5Mpa, when the grinding time is 48-56h, the grinding pressure is 10-11Mpa, when the grinding time is 56-64h, the grinding pressure is 10.5-11.5Mpa, and the grinding pressure in the later stage of grinding is 10.7-11.7Mpa; the pressure difference in the mill is controlled to be 2500-3000Pa.

2. The method according to claim 1, characterized in that: The feed rate of raw materials into the mill is 103-105t / h.

3. The method according to claim 1, characterized in that: The height of the retaining ring is 24-26cm.

4. The method according to claim 1, characterized in that: The air volume of the main induced draft fan of the vertical mill is 280000-350000m 3 / h.

5. The method according to claim 1, characterized in that: The power of the main induced draft fan of the vertical mill is 1250KW, and the frequency of the main induced draft fan of the vertical mill is 35-43HZ.

6. The method according to claim 1, characterized in that: The main motor current of the vertical mill is 150-180A.

7. The method according to claim 1, characterized in that: The storage time of the water slag entering the mill is 3-5 days, and the moisture content of the water slag entering the mill is 7%-10%.