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Analysis of factors affecting the measurement of kiln tail r

Date:2019-01-29 14:34     writer:admin     Views:

  “Homogeneous stability” is the main starting point for the production management of new dry process cement. The stability of system feeding coal is the most important. In the past ten years, the author has investigated nearly ten 5,000 tons production line rotors around the factors of coal stability. The coal situation under the scale, now from the actual production situation, the factors affecting the stability of coal are summarized as follows:

  First. Design and installation of rotor scale and conveying pipeline

  1. Control of the cone angle of the lower bin. In the new dry process cement plant process design manual, the design angle of the coal mill system pipeline is not less than 55 degrees, and the actual production shows that this angle is a bit too small. The pulverized coal bin cone of a company, when the arrangement angle is 60 degrees, the cutting effect is very poor, and the blanking area sometimes only accounts for 1/4 of the entire cone. The company changed the cutting angle of the warehouse from 60 degrees to 75 degrees. After the transformation, the cutting became very smooth, and the blanking area reached 1/2 or more.

  2. Selection of material for the unloading pipe, conveying pipe and bin body. The channels and warehouses for conveying pulverized coal are preferably made of stainless steel with a small viscosity/friction coefficient. A company changed the cone technology of ordinary steel plate material into stainless steel cone. After each technical repair, it can be compared when cleaning the coal powder bin. The adhesive material in the warehouse is greatly reduced.

  3. Design control of wind speed in the pipeline. The wind speed of the pipeline should be more suitable when it is about 30 meters. If it is too low, there will be pulverized coal pulse in the pipeline, which will cause coal to be unstable. Especially when there is no hot air when starting and stopping the kiln, the pulverized coal has high water content, such as: a company kiln head The coal supply Roots blower has no frequency conversion, and the coal grinding system is not equipped with drying equipment. In the initial stage of kiln ignition, it is a stable flame. When the air valve is slightly open, the coal supply pressure fluctuates greatly (the ignition pressure is higher than that during normal production). The influence of the bleed valve is large. When the coal injection concentration is high and low, after the shutdown, the coal injection volume is relatively stable.

  4. Design of scale allowance. A company has always had the problem of coal breakage. When the other factors are the same, the scale is changed from 412 (rotor diameter 1200mm) to 414 (rotor diameter 1400mm) rotor scale. The problem of coal breakage after technical transformation is solved.

  5. The position of the pulverized coal weighing scale and the arrangement of the conveying pipeline, and the resistance control. The rotor scale is arranged as close as possible to the kiln tail direction. To reduce the resistance loss along the path, the pipeline should be horizontal or vertical when it is arranged, so that the wind coal mixing is better, and the local resistance loss parts of the pipeline should be considered as much as possible. (including elbows, etc.).

  6. Installation of bypass piping. In order to reduce the pressure of coal feeding at the outlet of the Roots blower, a company added a connecting pipe between the exit of the Roots blower and the exit of the rotor scale, and installed a valve on the connecting pipe to control the air volume passing through the rotor scale. After the technical transformation, the coal feeding pressure at the exit of the Roots blower was reduced from about 37KPa to about 25KPa, which greatly reduced the crosswind between the rotor scale and the coal powder bin, and eliminated the hidden danger of the coal being poor due to the scale wind.

  7. Specification installation of the rotor scale (installation of the rubber expansion joint). When installing the scale body, the rubber expansion joint above the scale should be installed to ensure that all the rubber expansion joints above can effectively exert the effect of relieving the stress, and avoid the interference of the scale body sensor and affect the metering.

  Second, the selection of some spare parts of the rotor scale, the use and maintenance of the scale

  1. The precision of the upper and lower sealing plates and rotor of the rotor scale. When replacing spare parts, the equipment should be installed with high precision rotor and upper and lower sealing plates as much as possible, and the whole set should be replaced, and the gap between the rotor and the upper and lower sealing plates during use should be controlled to reduce the wind in the scale.

  Due to the problem of capital budget, a company used a rotor with lower precision. After the use, coal broke, and it was forced to replace the rotor with higher precision. The problem of coal breakage after replacement was solved.

  2. Ventilation matching of the rotor scale. During the use process, the wind speed of the inlet pipe of the rotor scale is guaranteed to meet the design requirements, and the wind speed of the three pipes is calibrated by the wind speed measuring instrument, so that the wind speed is V, V, V/2, so that the air-to-gas ratio is equal to each other. Equal pressure, reduce the internal wind, and ensure the normal transportation of coal powder.

  3. Inspection and maintenance during the operation of the rotor scale. The rotor scale timing belt cannot be slipped, and the wear condition is often checked to ensure that the line speed of the transmission wheel and the driven wheel are the same.

  In the production process, the balance of the rotor scale can also be dynamically adjusted by means of a hand-operator and other tools. When the ignition is started, the pulverized coal is large, and the coal can be properly enlarged when the coal is broken, the gap of the rotor scale is controlled at 20~25 during normal production. The road is more reasonable.

  4. Inspection of the sensor. During the operation, timely check the foreign matter such as coal on the rotor scale and ensure the normal use of the sensor.

  5. Specification calibration of the rotor scale. At the time of calibration, the wind turbine inside the rotor should be blown off to reduce the zero drift of the rotor scale during use.

  Third, the use of auxiliary equipment to maintain the stability

  1. Drying of compressed air. In order to ensure that excess water enters the silo through ring blowing, flow-assisting, etc., it is necessary to ensure that the compressed air is dry, and regularly check the air-conditioner outlet to dry the machine to ensure its use effect; at the same time, make timely release of the gas storage tank (increase The gas tank is periodically drained, etc.).

  2. The effect of the use of the warehouse help flow. Add a gas storage tank near the cone of the coal powder bin to ensure a relatively stable and sufficient gas source for the flow aid and the ring blow; at the same time, when the machine is shut down for maintenance, the ring blow and the flow aid are implemented one by one from the inside of the warehouse, and the filter membrane is checked according to the inspection situation. Diaphragm inflation hoses, solenoid valves, etc. are repaired and replaced to ensure the flow aid effect.

  3. Install a buffer tank above the rotor scale, and install a rotary feeder to set up an automatic control loop to ensure the stability of the warehouse weight. Note that the high-precision rotary feeder should be used during installation to ensure that the locking effect is good. At the same time, the soft connection is installed to avoid the various stresses on the top to affect the fluctuation of the bearing weight, thus leaving hidden dangers for the unstable coal.

  4. Kiln head Roots blower factory maintenance. According to the life cycle of the Roots blower, return to the factory for repair in time to ensure the stability of the fan performance, so as to ensure the stability of the pressure flow and other parameters of the coal supply source.

  5. Control of the air duct. Reasonably arrange the air-discharging pipeline, maximize the layout angle of the pipeline, eliminate the coal deposit, ensure that the interior is negative pressure, and add a single-machine dust collector at the wind-blown road according to the actual situation, and open the single-machine dust collection when the coal mill system is shut down. Guarantee normal wind.

  Fourth, the control of coal auxiliary factors under the influence

  1. The control of the water quality and fineness of the powder itself. On the one hand, the use of high-quality raw coal (low water, less debris, etc.), from the contract agreed to grasp the source control while doing a good job of process cleaning, on the other hand grasp the fine operation control of the coal mill system, for the production of better quality The pulverized coal creates conditions.

  2. Control of ash increment. Grasp the use and control of hot air quality, reduce the dust content of hot air source, and stabilize coal quality. Once the hot air source has a large dust content, the density will be changed due to the change of hot air incorporation or the settlement efficiency of the settling equipment. Unevenness will affect the stability of the coal, especially when opening and stopping the grinding, pay more attention to the use of hot air.

  3. Insulation against the wall. Adding helium sheets, heating cables, etc., at the same time, sealing the environment to ensure a high ambient environment, reducing the temperature difference between the inside and outside of the warehouse, and preventing the occurrence of walling.

  4. The position is stable. Controlling a reasonable pulverized coal warehouse position is conducive to stabilizing the coal.

  Fifth. Impact of other external factors

  1. The influence of pressure fluctuations in the preheater system. Ensure that the design parameters of the preheater system are reasonable, and in the inspection process, the key parts, such as the spreader and the size of the shrinkage chamber of the smoke chamber, are fixed and repaired. In order to ensure that the feeding is stable, there is no possibility that the material will continue to fluctuate or the pressure will continue to fluctuate greatly.

  2. Overhaul control of coal mill system. Check and replace the bag to collect the dust filter bag; when cleaning the bag to collect the dust ash hopper, clean the pulverized coal bunker wall material, etc., the operation process should be standardized, the overhaul and control should be grasped, and the cotton sand and dust bag should be avoided. Clean up tools and other debris into the pulverized coal bin.

  3. The system is rainproof. Do a good job of rain protection of the system, and prevent rainwater from entering the dust collection, reamer, and coal powder warehouse.

  4. Do a good job of the insulation of the whole system, especially in the winter, when the temperature difference is large, the wall is most likely to be caused by the pulverized coal moisture. After the wall is formed, once the wall material enters the rotor scale, it will affect the stability of the coal.

  5. Do a good job in the safety management of the system to avoid spontaneous combustion of coal powder. After the self-ignition, the residue will enter the coal powder bin and will seriously affect the coal or even the coal.

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