Roller system problems and improvement measures

Date: 2019-07-04 Views:

I. Analysis of problems in the roller press system


Since the introduction of the German KHD roller press technology in the 1980s, the specifications of the domestic roller press have been developed from Φ1200*500mm to Φ2200*1600mm, and the main motor power has been developed from 220kW×2 to 2240kW×2. The mill's output has grown from 70 t/h to 350 t/h. Now there are many manufacturers of roller presses, and there are many roller presses used in cement plants. Hefei Institute HFCG120*50, HFCG140*80, HFCG160*140, Chengdu Lijun Φ1400*400, Φ1700*1000, Φ1800*1200, CITIC Heavy Industries Φ1200*800, Φ1700*1200, Tianjin Institute Φ1400*1200, Φ1800*1200, Φ2200*1600; supporting: SF series scattering classifier, “V” classifier, horizontal classifier. The supporting mill has open circuit and closed circuit; the early small roller press is equipped with large grinding, and the later large roller pressing machine is equipped with small grinding. It has made great achievements in improving production capacity and reducing power consumption, but its problems once it is difficult to make major changes once it reaches the cement plant of the manufacturer.

German technology introduced in China, but due to the conditions at the time, equipment technology, material level, the actual level of Germany is not reached; the following problems exist

1. At present, most domestic roller presses adopt the control mode of low pressure and large circulation. The pressure is low, the average roller pressure is 60-80Mpa, the peak pressure is also 120-150Mpa, the proportion of fine powder produced is small, and the fineness of the roller press is obtained. 0.08mm sieve residue is 70-80%, 0.9mm or more is more than 50%, the extrusion effect is poor, and the formed cake is few, so the effect of the roller press is not achieved, and it can only be equivalent to the crusher.

2. The arrangement of the cylinder of the roller press is small, the motor power and the speed reducer are too small; the crushing material can not be met under the low pressure; the accumulator is not in the early stage of pressure control, and the nitrogen airbag accumulator is added later. Slow down the impact; but its cushioning performance failed to achieve good results, the cylinder vibration is large, the stability is poor; the effect of high pressure extrusion is not achieved.

3, the roll gap control has two ways, one is constant pressure control, one is constant roll seam control; PLC control mostly adopts German Siemens, running roll gap and pressure fluctuation is large, plus roller press work extrusion The distance is very short, the extrusion does not reach the crushing, the working resistance fluctuates greatly, and the motor running current fluctuates greatly; and once the material is crushed and the roll gap is stable, the motor current fluctuation is small.

4. At present, most of the roller press feeding devices feed the material directly into the roll gap after passing through the silo, and pull the material between the two rolls, that is, the so-called pull-in angle of the roll press for extrusion; flow adjustment The amplitude is limited and it is difficult to accurately and stably control; at the same time, the silo has a high position and a material segregation phenomenon, which sometimes causes the roller press to vibrate greatly; some improved feeding devices can control the opening degree, but the effect is not good and cannot be achieved. Effectively control traffic.
5, iron remover, hard object cleaning system is poor, the system has iron removal, but can not ensure that no iron, hard objects, especially stainless steel, heat-resistant steel, high-chromium steel balls and other hard objects; due to roller press Material circulation, into hard objects, iron blocks can not be ruled out, it is very harmful to the roll surface in the system.

Second, the analysis of the problems in the use of roller press


1. Ball mill with roller press combined with grinding system has double closed circuit and single closed circuit system. The ingredients are stable and controllable, and the stability is good. The roller press system is a circulation system, and there is a silo overbalanced. Control, but the stability of the grinding and flow stability is difficult; the operation is more difficult! Reasons: (1) Because there are silos, there are feeds, there are feeds, the size is large, and sometimes segregation occurs, and the control is very difficult. (2), the roller press has a small amount of material, and the circulating load is very high, generally 300-400%, and it is difficult to control the feeding of the roller press, which makes the control of the roller press more difficult. (3), the fineness of the grinding is generally 0.08mm, and the remaining amount is 20-50%. The flow rate of the grinding is more varied, and the flow cannot be displayed. The fineness index and experience are adjusted, and the actual operation is difficult.

2, the control of the central control, in addition to the ingredients, quality indicators, the adjustment of the roller press can not be done, the hydraulic system control is generally in the PLC control, the lower limit, upper limit, upper limit, PLC control is not perfect, the general choice It will be retired; the central control will not operate. There are some misunderstandings in the central control operation. Many manufacturers use the circulating fan speed to adjust the silo position. This can not only be done, but also causes disorder to the mill working conditions.

3. When the roller press is in use, the roller surface will be peeled off, the maintenance is troublesome, the workload is large, the peeling is still to be turned on, and the operation is more difficult. There are already casting nail rolls and alloy rolls; the actual use is not much.

Third, the reform measures and effects of the roller press system


1. Adopting the control mode of high pressure and small circulation, the average rolling pressure is 120-150Mpa, the peak pressure is also close to the ultimate pressure of crushed material at 260-300Mpa, and a large amount of material can be formed after extrusion, and the fine powder produced (roller) Press discharge port) fineness 0.08mm sieve residue is about 50%; or the original fine powder 0.08mm sieve residue is increased by 10-20% on the basis of 70-80%, reaching 0.08mm sieve residue at 60% about.

Modification method: increase the cylinder bore or increase the cylinder pressure. If the pressure of the current cylinder is lower, increase the cylinder pressure. A buffer device is added to the bottom of the cylinder to reduce the vibration, and the original accumulator buffer, double buffering can achieve a stable effect.

2. Increase the roll gap adjusting device (patent technology) of the roller press, using constant pressure and constant roll gap control. The roll gap is pre-adjusted under a certain pressure. Even if material segregation occurs, the fine powder can stably pass through the roll press. It will not cause vibration due to the compressed air gap being too small; the adjustment method of the roll gap will change, the direction of the force of the roller bearing seat will change, and the impact on the middle part of the beam on the roller press will no longer occur, and no sharp resonance will occur; The ultimate pressure of the crushed material can form the material. Through reasonable adjustment, the roller runs more smoothly, and the roller press reaches the normal running state. The two main motor currents reach the rated current of 80-90%, and the operation is small within a certain range. The amplitude of the swing, which indicates that the roller press inputs the energy required for the crushing of the material.
3. Renovate the roller press feeding device to stably control the material flow rate to achieve the appropriate material flow rate; refer to the German Perseus technology to improve the roller press feeding device: 1. Accurately estimate the feed flow rate and flow rate. The flow rate and flow rate are stably controlled; and the feeding mode is directly between the two rolls of the roller press, which reduces the sensitivity of the roll press to the feed size. Second, the side baffles have been redesigned to prevent serious leakage at the edges; the flow control at the ends is increased at both ends, and the width of the feedstock at both ends can be adjusted according to the situation.

4. Improve the control of PLC, adopt constant pressure constant roll gap control; stabilize the pressure pressure of the cylinder while stabilizing the feed, reset the PLC parameters to achieve stable pressure; or replace the PLC control; and once the material is crushed And the roll gap is stable, the motor current fluctuation is small.

5, the working distance of the roller press is very short only 6-8 cm, the pressure is very high in 500-1000 tons; the effect of removing the iron and hard object cleaning system is very important, to ensure that the roller press does not enter the iron block, hard objects, especially It is a hard object such as stainless steel or high-chromium steel ball. At present, most of the magnetic tools used in the iron remover are small, and the effect is poor. Of course, many manufacturers have already solved it, but its importance should be recognized, especially if the roller surface is seriously damaged. Iron and Zhenjiang gold stone non-metal iron removal; because the iron block once entered the roller press, it can not be automatically discharged.

At present, the domestic roller press has poor extrusion effect, and the formed cake is few, so the effect of the roller press is not achieved. This shows that the roller press has great potential to tap the potential, and we have very few in the field. The roller press press roller press fine powder 0.08mm sieve is about 50%, such as Germany Perseus. At the same time, we have proved in practice that the roll press has great potential. Through our transformation, the fine powder (roller discharge port) produced fineness of 0.08mm, the sieve residue is increased by 10-20%, and the roll pressure can be achieved. The machine's discharge port has a fineness of 0.08mm, the sieve residue is about 50%, and the 0.9mm or more is less than 30%. At the same time, the roller press runs more smoothly.

Through the above transformation, the roller press operation can be more stable, the running current of the roller press is 80-90% of the rated current, and the roll gap fluctuates smoothly in the range of 0-5 mm; the feed control is stable, and even if the material has segregation phenomenon, the roller The press operation is also stable, the roller press system is stable in circulation, and the flow rate and fineness control are stable. In the case of the same quality control indicators, it can increase the production time of Taiwan by 20-40%, and the operation is more stable.

The power configuration of the roller press motor is too small. There are many roller presses in a company. For example, if a large-size roller press motor is used for a small roller press, the small-size roller press can achieve the effect of the larger roller press. Production capacity will be greatly improved.

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