What is the cause of abnormal fluctuations in the roller press?

Date: 2019-07-04 Views:

Several tricks to deal with the abnormal fluctuation of the roller press

1 Overview


Our company adopts CLFl70×100 roller press with Vx8820 type powder separator for pre-grinding, and combines with 14.2m×14.5m cement mill to form an open-circuit combined grinding system. The raw materials of the mixing station are first upgraded to the top of the Vx8820 type separator to enter the classifier for powder selection. The fine powder is driven by the wind of the circulating fan into the double cyclone to collect the grinding, and the coarse particles fall to the steady flow bin. Enter the roller press for rolling. The material after rolling by the roller press is upgraded to the V-type separator for powder selection together with the raw materials of the mixing station. In the actual operation process, there are some abnormal fluctuations in the rolling machine, which generally include fluctuations in current parameters such as current, pressure and roll gap. Because these parameters are related to each other, when one of the parameters has a large fluctuation, the other parameters also change accordingly, which will affect the stable and efficient operation of the roller press, and then will be serious. Affect the smooth operation of the grinding system and the quality of the cement produced, resulting in an increase in cement power consumption. Therefore, the operation control of the roller press is extremely important in the process of central control operation.

2. Reason analysis and solutions


In the process of central control operation, the fluctuation of the roller press can be summarized as three reasons: first, the influence of material factors; second, the electrical/mechanical failure of the roller press; and third, the influencing factors on the process flow.

2.1 Influence of material factors

2.1.1 Excessive amount of fines in the material passing through the roller press


The fineness of the fine powder is low, and gas is interposed therebetween. When the excess amount of fine powder is squeezed through the high pressure zone, the compactness will increase, but the gas trapped in the fine powder will aggregate into bubbles, and the bubble will be crushed and broken under the action of high pressure, thereby causing the roller press to vibrate. Secondly, the fine powder is easy to slide. When it is pulled into the high pressure zone for extrusion, it is easy to slip, which also causes the roller press to vibrate, and in this case, the fluidity of the material is strong and stable. The grading is more serious when passing through the roller press. When the mixing of the particles in the material on the working surface of the roller is severely uneven, the unevenness of the roller surface may also cause fluctuation of the roller press. In addition, when there is too much fine powder, it is also possible that the collapsed material causes the current of the grinding head to rise suddenly and jumps and crushes the bucket.

In this case, the opening of the electric push rod of the small roller press should be appropriately closed in the middle control operation; increase the pulling of the circulating fan or close the small roller press to force the material to reduce the throughput of the material. If the mixture is mixed with cinder, the amount of incorporation may be temporarily reduced or mixed for a few minutes. Because the amount of powder in the cinder is more, the amount of fine powder in the steady flow bin can be reduced by controlling the amount of cinder.

2.1.2 The temperature of the material of the roller press is too high


When the temperature of the material is too high, the fluidity is strengthened, the classification is intensified, and the material layer passing through the roller press is unstable, thereby causing the fluctuation of the roller press; at the same time, the excessive temperature of the material may affect the lubrication of the roller press, and the life of the main bearing is reduced. And the wear of the roller surface and side baffle of the roller press is intensified. Intention to check and replace; large refractory bricks often appear after kiln inspection, at this time should strictly control the proportion and particle size of refractory bricks into the clinker warehouse; difficult to control is mainly the use of cinder, due to some suppliers The coal slag is not broken, and the particle size of the coal slag entering the plant can reach more than 150 mm, which is seriously exceeded. Therefore, it is recommended that this part of the large particle cinder be crushed before use.

2.2 Roller press caused by electrical/mechanical problems

2.2.1 The side baffle of the roller press is seriously worn


When the baffle on both sides of the roller press is seriously worn or the side baffle wears seriously, the working gap value becomes larger, the thickness of the material layer passing through the roller press is different, the roll gap is skewed, the roll gap difference is obvious, and the roll press is Frequent correction, the roller presses appear relatively large fluctuations. At this time, the work efficiency of the roller press is reduced. Under the condition that the damper of the circulating fan remains unchanged, the material level of the steady flow bin rises and the current of the hoist is reduced. The normal gap between the side baffle of the roller press and the two ends of the roller is generally between 2 and 3 mm. According to the survey, the working gap between the side baffle of the roller press and the two ends of the roller is between 1.8 and 2.0 mm.

When the side baffle is found to be worn, the gap between the side baffle and the roller should be adjusted in time, otherwise the wear will be intensified; when the side baffle is worn seriously, it should be replaced in time. In daily production, one or two sets of side baffles are always available to deal with temporary tamper replacement; and equipment failure prevention mechanism is implemented, which requires 7 to 10 days of normal production to use side-baffle and roller clearance during downtime. Check the measurement once. If it exceeds the allowable range, it must be adjusted and recorded in a timely manner.

2.2.2 Roller surface wear and tear of the roller press is serious


When the roller surface of the roller press is worn and peeled off, the surface is uneven, the material of the roller press can not be effectively squeezed, the roller is unevenly stressed, and the pressure, current and roll gap change frequently, which causes the roller press to fluctuate. Big. At the same time, there are many pellets in the material of the roller press, less cake, the output of the mill is reduced, the circulation amount in the roller press system is greatly increased, and the powder is more and more, which tends to cause frequent weighing of the weighing bin.

In this regard, it is necessary to check whether the iron remover and the metal detector of the grinding head system work normally; always check the iron parts on the iron separator of the person V to make the roll surface peeling off in time; when the roll surface peels off seriously , timely repair or re-surfacing.

2.2.3 The displacement sensor or valve block of the roller press is faulty


The fixing bolt of the roller press displacement sensor is loose or the displacement sensor is damaged, the roll gap is distorted, the roller press is pressed and decompressed frequently; there is a problem with a valve member on the valve block, the pressure cannot be maintained, and the roll gap changes frequently.

At this point, the following aspects should be checked one by one: one should check whether the tightening bolt of the displacement sensor is loose; the other is to pressurize the roller press to the pre-applied pressure to see if the original gap is normal, whether the displacement sensor is faulty or not; Add pressure and then stop, see how the valve block is holding pressure; Fourth, check whether the pressure of the accumulator on the valve blocks on both sides is too different and there is imbalance. In addition, it is necessary to check frequently whether the exhaust pipe of the hydraulic cylinder is too oily and the hydraulic cylinder is oily. Then according to the reason of the search, the corresponding technical measures can be taken to solve the problem.

2.2.4 Roller reducer or roller bearing is faulty


When the roller press is installed, the concentricity of the main motor and the reducer is not well adjusted; or after the roller press is operated for a period of time, the lock disk bolt of the roller press is loose. These may cause relative displacement between the reducer and the roller shaft, which makes the roller press be more serious and unstable during operation; at the same time, the main bearing of the roller press, the reducer bearing and the gear are damaged, thus causing Roller vibration and motor current fluctuations. In this case, re-check the concentricity of the high-speed shaft of the reducer and the output shaft of the motor to reduce the vibration or runout caused by the asymmetry; usually check and tighten the bolts of the lock plate and the reducer bolts. Anchor bolts and side fence bolts, and ensure the lubrication of the roller bearings to ensure smooth running of the roller bearings.

2.2.5 Problems with the electronic control system of the roller press


There is a fault in the electronic control components of the roller press (such as the poor contact of the carbon brush of the roller press motor), which causes fluctuations in the control parameters, which may be caused by a sharp change in a certain parameter.

When this happens, stop the material first and observe the trend of the various parameters of the roller press during empty running. When the exclusion is not a mechanical problem, the electrician should be notified to carefully check the relevant electronic control components with large changes in parameters, and if necessary, replace them in time.

2.3 Factors affecting the process


All process problems that cause severe grading of the eccentricity in the steady flow chamber may cause the roller press to fluctuate more. Specifically, there are the following aspects: the steady flow bin is heavily biased and the steady pipe flow of the roller press under the steady flow bin or the foreign matter jam is not smooth; or the material selected by the person V is not evenly distributed; or V is selected The loose grid is seriously worn; or the V-selected steady-flow bin is not correct; The corresponding measures that can be taken are: improving the uniformity of materials into V selection; timely repairing or replacing the worn-out scattering grid; preventing material grading from being too severe; often checking whether the slippery tube has any material or foreign matter jamming and timely Clean up to ensure that the cutting is stable.

3, the conclusion


After more than ten years of application and research in China, the roller press has been continuously improved and its operation technology has been continuously improved. With the deeper research and development of extrusion grinding technology, the roller press and its process system will be more perfect. It is believed that it can achieve higher and better economic benefits under the premise of ensuring safe and stable operation of equipment.

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