Lao Zhang isCement industryThe inspector, at two o'clock in the middle of the night that day, the central control room alarmed-the outlet temperature of the high-temperature fan was abnormal. He picked up his flashlight and went straight to the end of the kiln. Before he could get there, he stepped on a foot of dust. Something is wrong. How can there be such thick dust on the ground? Looking up, the one on the pipeMetal Corrugated Expansion Joints in Cement IndustryThe corrugated roots were popping out like peppered flour. He scolded, took out the intercom and called out to the monitor. Ash leakage is too common in dusty pipelines, but if it is not handled well, it can be shut down at the light and the whole bellows will be worn out at the worst, so the loss will not be a matter of thousands of dollars.
Where did the ash leak come from? Three words: grinding, vibrating and crooked
Why does the metal expansion joint leak ash? To put it bluntly, there are three words: grinding, vibrating and crooked. Grinding means that the hard particles in the medium scour the bellows wall for a long time, especially after the guide tube is not installed or the guide tube is worn out, the ash directly hits the corrugations. Think about it, no matter how thick the wall of the bellows is, it can't bear the grinding day and night, and the trachea begins to leak when it is grinded. Vibration is the vibration of the pipeline causing the flange bolt to loosen, the sealing gasket to fail, and ash to drill out from the gap. In the middle of the night, the thermal expansion and contraction of the pipeline are the most violent, and the vibration is the most obvious. As soon as the bolts are loosened, ash leakage comes. Crooked, due to large deviation of pipeline alignment during installation, or improper selection of expansion joint, such as usingUniversal corrugated expansion jointTo resist large displacement, as a result, the lateral displacement is too large, and the bellows is fatigued cracked. Lao Zhang's one is the one with the most severe leakage-the root of the ripple is directly worn through, just like a sieve.
What should I do if the kiln can't stop after emergency repair in the middle of the night?
What about the scene? It is definitely safest to shut down and replace it, but the kiln can't be stopped for emergency repair in the middle of the night. Lao Zhang and others tried a local method-using iron hoops and high-temperature sealant to plug the leak first, which can last for two or three days. But this cure the symptoms rather than the root cause, and the ash still comes from elsewhere. To solve it completely, it depends on the size of the leak. If it is just sealing surface leakage, changeDouble-sealed single-axis circular baffle doorThe sealing ring will do, and it will take half an hour to disassemble and assemble. If there is trachoma or fine crack in the bellows body, you can use repair welding + polishing, but it must be operated by a certified welder, and nondestructive testing must be done after welding-don't try to save trouble, the weld seam is not treated well, and the leakage will be more severe next time. If the bellows has been significantly thinned, then don't hesitate to replace itHigh temperature axial expansion jointAnd must be equipped with a thick guide tube-don't underestimate this thing,Specific Function of Expansion Joint Guide TubeIt is to block ash and divert flow. Without it, no matter how expensive the expansion joint is, it won't live long.
Changing the expansion joint is also particular, install backwards equal to white install
Lao Zhang and the others later changed to one with its own double guide tubesCorrugated expansion joint for power station industryThe material was changed from 304 to 316L, and the number of corrugated layers was recalculated according to the actual pressure. Pay special attention when installing: Don't lock the tie rod nut in a hurry, and adjust the pre-compression amount according to the direction arrow given by the manufacturer. Here to remember,The direction of the arrow of the expansion joint refers toIf the medium flow direction is reversed, it is equivalent to white loading-the opening direction of the guide tube is wrong, and the ash is directly poured back into the corrugation. Also, the flange bolts should be tightened diagonally three times. Check the manual for the torque value, and don't rely on your feeling. By the way,Function of expansion joint tie rodIt is limit and protection, but it can't be used to forcibly straighten the pipeline, otherwise the tie rod will bear lateral force, but will accelerate failure. Lao Zhang has suffered this loss before. The tie rod was screwed too dead, and the pipe expanded by heat, and the bellows was directly cracked.
Prevention is more valuable than emergency repair. Don't wait for a leak to rush
But at the end of the day, prevention is worth more than emergency repairs. Lao Zhang's workshop later set a rule: check the wear of the guide tube with an endoscope once a quarter, and replace it in advance if it is found that more than half of the wear is worn. At the same time, the supports of the peripheral pipeline are re-adjusted, which reduces the extra displacement of the pipeline. In addition, they directly avoid high-temperature dusty smoke when selecting the modelNon-metallic expansion joint(For fear that it is not wear-resistant, the fiber fabric will rot as soon as it is ground), give priority to useMetal Corrugated Expansion Joints in Cement IndustryOrHigh temperature axial expansion jointAnd requires the manufacturer to thicken the wall thickness of the bellows by 0.5mm as the corrosion margin during design. As a result, the frequency of ash leakage has dropped from three or four times a year to once every two years. To put it bluntly, spending money on selection and maintenance is much more cost-effective than getting up in the middle of the night for emergency repairs.
So you see,Ash Leakage Treatment of Metal Expansion JointThis broken thing seems to be an equipment problem, but in fact, it is interlocked from selection, installation to maintenance. Next time this happens in your factory, don't rush to scold the manufacturers for selling things. Think about it first-is the deflector still there? Is the flange bolt loose? Is the pipeline right? Figure it out, that dust leakage is not a fatal thing. If you are really unsure, make a phone call and ask us old salesmen who have worked for more than ten years, and recommend the most suitable products to you, which can save a lot of money. After all, who has trouble with money?