Understanding Roller Presses in One Article (2)

Chapter 3 Roller press operation and control adjustment

I. Conditions for stable operation of roller press

1、 Pressure adjustment should be reasonable. Special attention must be paid to the formation of roller slit on both sides of the dynamic roller, so that the added pressure can be applied to the material.

2、Side baffle adjustment should be reasonable. The side stopper should be as close as possible without touching the end surface of the roller to prevent the material from overflowing from both sides without extrusion.

3、The adjustment of the inclined insert plate should be reasonable. If the material fluidity is poor, the inclined insert plate should be lifted to increase the processing volume to open the roller slit; if the material fluidity is good, the opposite operation.

4、The pad iron should be adjusted reasonably. When the roller press is working, the roller gap should be kept between 10 and 30mm, and both sides should be basically equal.

5、Weighing bin position control should be reasonable. On the premise of stabilizing the position of the bin, adjust the best position according to the actual situation of the process line.


Second, the roller press site inspection notes and processing

1、High temperature of roller bearing in operation.

(1) Insufficient cooling water of the system or high-water temperature of the system causes high temperature of all four bearings of the roller press.

(2) The cooling water pipe valve is damaged, resulting in insufficient opening, causing insufficient water flow.

(3) The water temperature of inlet water pipe is normal, but the temperature of return water pipe is high, mainly because the pipeline is blocked and the return water is not smoothly caused by high bearing temperature.

(4) Temperature measurement points are damaged, testing and replacement.

(5) Insufficient oil supply, resulting in grease dryness, poor lubrication caused by high bearing temperature.

(6) roller bearings are defective, need to be processed or replaced.

2, hydraulic coupling fusible alloy melts easily.

(1) fusible alloy melting point temperature selection and the actual working environment does not match; the alloy melting point temperature is too low.

(2) Fluid coupling oil filling amount does not meet the standard.

(3) The roller press has large power and large fluctuations during operation, overload phenomenon, or the sudden entry of foreign matter between the two rollers, resulting in liquid coupling overload protection, confirm the use of iron remover and sieve separation.

3、Poor extrusion effect of roller press, cannot form material cake.

(1) The material hardness is high, and the working pressure is too low. When the motor current is within the safe range and the active roller has roller slit, the working pressure of the system can be increased appropriately.

(2) The roller surface of the roller press wears seriously, resulting in the increase of the original roller slit, and the main motor current is low, which affects the extrusion effect.

(3) The material size is too large, the roller press motor roller fluctuates greatly; or the material size is too fine, the roller press motor roller does not do work without extrusion effect, must replace the adapted pad iron.

(4) roller surface wear, the original roller seam changes, according to the wear and tear and combined with the formation of the material cake to replace the appropriate pad iron.

Special attention.

The clinker sources of the grinding station are all multiple base clinkers with different sizes of clinker particles, so the pads of different thicknesses need to be prepared in advance to adapt to the changes of different clinker particles and minimize the operating fluctuations in order to ensure the stable operation of the roller press.


Chapter 4: Common fault analysis and treatment of roller press

I. Vibration and noise of roller press machine body
1. Material reasons.

(1) The use of clinker segregation phenomenon is serious, if the proportion of fine particles is high, by the extrusion, it is easy to flow directly from the roller, not easy to form a material cake, resulting in the material in the steady flow bin collapse of the punch phenomenon, causing the roller press vibration.

(2) The high C2S content in the mineral composition of clinker and the poor ease of grinding lead to the vibration of the roller press.


Solution measures.

(1) Adopt multiple discharging ports for discharging materials at the bottom of the clinker warehouse, or modify the drop point at the entrance of the clinker warehouse to prevent clinker from segregation.

(2) Actively coordinate with relevant departments, reasonably optimize the system ingredients, increase the control of raw material and clinker rate, increase the C3S content of clinker and improve the grindability of clinker.

2. Equipment causes.

(1) The gap between the side stopper of roller presses and the end surface of roller is large, causing some small particles to leak out from the gap without extrusion, and the proportion of fine material in circulating material increases, causing vibration of roller press.

(2) The side stopper or blocking plate is in contact with the roller, causing friction between the metal and making abnormal noise.

(3) If it is a combined grinding system, the guide plate of V-type powder selector or the inner cylinder body is worn out, causing the amount of circulating material to increase and causing the roller press to vibrate.

(4) The roller press stop iron is not adjusted correctly, especially the newly replaced squeeze roller, the pad iron is too thin, causing the dynamic and fixed roller to rub against each other.


Solution measures.

(1) timely check the gap between the side stopper of the roller press and the end face of the roller, by adjusting the adjusting screw, so that the gap is controlled at about 2mm, adjustable stopper does not touch the roller surface as a principle.

(2) Regularly check and clean the debris at the lower material entrance of the V powder selector, check whether the deflector plate and the inner cylinder are worn, and repair and change them in time. Check whether there is wind leakage at the material inlet of the steady flow bin and the locking wind device at the lower material outlet of the cyclone, and deal with it in time.

3、Cause of process operation.

(1) When the deviation of the gap between the left and right rollers of the roller press is large, it is not adjusted in time to cause large vibration of the roller press.

(2) For the combined grinding system, the circulating fan air door of V-type powder selector is too small, which fails to separate the fine powder of the system in time, resulting in the dispersion and grading function of V-type powder selector not playing sufficiently, causing the amount of fine powder in the coarse powder back to the roller press to be too much, causing the roller press to vibrate.


Solution measures.

(1) Timely adjust the pressure of the roller to reduce the deviation value of the roller.

(2) Properly adjust the circulating fan air volume to improve the scattering and grading efficacy role of V powder selector. Increase the feeding volume of V powder selector, so as to reduce the amount of return material to reduce the amount of fine powder into the roll material and improve the grinding efficiency.


Second, the roller presses partial roller

Reasons.

1、The material entering the roller press has the phenomenon of segregation, resulting in large material particles on one side, and the material column above the roller press cannot form a stable, dense and full material column, the impact of the material column on the roller is large, and the pressure on both sides of the roller is unbalanced and unstable, and the hydraulic system is too late to correct the deviation.

2、The downward material of the feeding tube is partial, and the material cannot enter the middle of the two rollers vertically.

3、The side stopper on both sides of the feed opening is worn out or the gap is big, producing different amount of material leakage on both sides of the edge.

4、The inflation pressure in the accumulator on the left and right sides is not equal, which causes a big deviation of the working pressure on both sides and leads to the deviation of the roller seam.

5、The thickness of left and right gasket is not consistent. Or one side of the roller surface has a pit to replace and adjust in time.


Solution measures.

1、Strictly control the particle size of the material into the roller to ensure the uniform distribution of the material after entering the bin and reduce the segregation effect in the bin.

2、Must ensure that the material enters the middle of the two rollers as vertical as possible.

3、Use the top bar on both sides to adjust the side baffle, generally the smaller the distance between the side baffle and the edge of the roll, the better.

4、The accumulator stops to check the correction pressure and replenish the gas in time to ensure that the pressure on both sides is basically equal.

5、Timely replace and adjust the left and right side pads to ensure the same thickness.

6、The roller surface has pits and needs to be repaired in time.

Special attention: large iron pieces or other foreign matter mixed in the material of the incoming roll will also cause abnormal vibration of the roller press and cause a large jump stop of the roll seam difference, so the work of the iron remover should be checked regularly to ensure its magnetism.


Three, roller press small bin flushing material causes

(1) The volume of material passing through becomes large, the material level of small bin decreases faster, and a certain material pressure is not formed, so the material is recoiled into the roller press with a large amount of air, causing the collapse of material.

(2) Due to the wear of the lower end of the side baffle plate of the roller press or the gap between it and the roller end surface is too large, which aggravates the edge effect and causes the large amount of side material.

(3) The comprehensive moisture of incoming materials is too high (industrial gypsum, slag, coarse ash, etc.), the wall around the small bin is seriously knotted, the effective volume is reduced, the actual storage volume is insufficient, the roller press passes through a large amount of material, and the feeding is insufficient.

(4) The feedback information of the small bin weighing instrument is not accurate, which cannot truly reflect the actual weight of the materials in the bin.


Solution measures.

(1) Stop the materials with excessive moisture from entering the plant, or take active measures to expand the capacity of the yard and use it again after drying, and clean the caking wall of the small bin in time to ensure the smooth flow of materials; for the roller press with V powder selector, the moisture of the integrated material cannot be high (the integrated moisture is less than 1.0%), otherwise, it is easy to cause the scattering plate to crust and sticky material, increase the system back to powder, reduce the finished product, and easily trigger the phenomenon of roller press flushing

(2) For the amount of side material is too large, try to put the inclined insert plate down and tighten the fixing screws on both sides of the top rod after adjustment to prevent the inclined insert plate from shaking and leading to large power fluctuation of the roller press. And check whether the side stopper is top in place (the closer to the side of the roller the better) to effectively solve the edge effect. In addition, proper adjustment of the dividing valve opening degree or circulating fan damper opening degree is also an important means to reduce the amount of edge material.

(3) Check whether the thickness of the pad iron on both sides is consistent, and adjust the moving roller pad iron reasonably.

(4) Check whether there is leakage in the hydraulic system (the pressure can‘t be kept will lead to large roller slit), ensure that the nitrogen pressure is in line with the system working pressure, the system pressure setting should be set according to the system working pressure change and set the corresponding pressure, the nitrogen charging pressure of large accumulator is higher than 20-30% of the system working oil pressure, which plays a protective role for the system, the nitrogen charging pressure of small and medium accumulator is 60-65% of the system working oil pressure, which plays a buffering role for the system. It plays a buffering role for the system.

(5) The two load sensors of the roller press should be installed at an angle, and the center point of the drop port of the steady flow bin and the discharge of the small bin should be consistent.


IV. Hydraulic system failure and treatment

1、Pump station pressure can‘t come up

(1) increase or decrease the pressure valve spool blockage, seal aging, broken, also cause the pressure cannot play, check and replace.

(2) check whether the oil tank suction pipe is aging and broken oil leakage, whether the joint is off or loose and the formation of internal leakage, if the problem reinstallation suction pipe or replacement can be.


2、Pressure can be added, but cannot keep the pressure

(1) check the oil circuit, oil cylinder, etc. whether there is a lubricant leakage phenomenon.

(2) increase or decrease the valve spool blockage, seal aging, broken, pressure increase on the leak caused by the need to check and clean, and replace the damaged seal.

(3) the program set pressure value is small, relief valve unloading pressure in advance, need to recalibrate the program.


3、System pressure cannot reach the rated pressure

(1) Check whether the oil station outlet filter is clogged, and clean it in time.

(2) Check whether the oil level of the tank is normal after pressurization, whether it is lower than the oil suction port, if the oil level is low and timely replenishment.

(3) Check whether the oil temperature of hydraulic oil is too high. Generally, when the oil temperature reaches above 50 degrees, it is difficult for the pump station to pressurize the system. Check the operating conditions of the roller press and reduce the frequent start of the hydraulic pump to prevent the oil temperature from being too high.

(4) Whether there is leakage in the relief valve, whether the spool of the pressure increasing and reducing valve is blocked, the seal is aging and broken, which also causes the pressure to increase less than the rated value.


Five, dry oil lubrication system failure and processing

1, the oil pump does not oil

(1) piston pump oil suction port blockage, clean.

(2) the lack of grease in the oil drum, not timely replenishment.

(3) piston pump damage, check and replace.


2, the oil pipe is not oil or oil volume is low

(1) distributor body plunger hole blockage, disassemble and clean.

(2) The plunger of the distributor is worn out, resulting in low oil output, check and replace the distributor when the plunger is badly worn.


Special attention: the large oil drum should be placed in the closed box to prevent grease pollution.