Find out what kind of expansion joint cloth you are using first-don't make a mistake
When you go to the scene, you see that the layer of cloth on the flue is ripped apart. Don't rush to dismantle it, you have to confirm the model first. The desulfurization flue basically usesNon-metallic expansion joint (fabric fiber expansion joint), according to the flue shape, the most common isRectangular non-metallic expansion jointOr in a round shape. How to distinguish? Looking at the flange face – square or round? Measure the original dimensions (length, width, thickness), especially the thickness, don't buy the wrong one. Tip: Turn over the equipment nameplate, which is usually marked with the model number. Check it against the product information in our station. Two days ago, I met a customer. Because I didn't look at the nameplate, I bought a round cloth. As a result, the flange was rectangular, so I was throwing it for nothing.
Then why are non-metallic expansion joints so common? Because it is corrosion resistant and can absorb multi-directional displacement, the key is that the cost is lower than that of metal. In particular, there are many acidic gases in the desulfurization flue, which can not be carried by ordinary metal parts, but fabric fibers are more durable. From your stationNon-metallic expansion joint (fabric fiber expansion joint)There is also an acid-resistant coating version. Don't buy the wrong model cheaply, otherwise you will have to change it in half a year.
Don't rush into the preparation work before dismantling old cloth
Downtime! Must ensure that there is no smoke in the flue and the temperature drops to normal temperature (below 50℃), otherwise don't blame me for not reminding me for burns. Once I went to the scene with an old electrician. They tried to save trouble and didn't cool down. As a result, when their hands touched the flange, they blistered-do you think it was wrong?
Wrench (one set each of plum blossom and opening), crowbar, safety rope, protective gloves, goggles. By the way, don't forget to bring a marker. Step 2: Mark the position of flange bolts, and it is best to draw a mark on the flange to prevent misalignment during reassembly. NOTE: If matchedDesulfurization flue gas baffle doorFirst, confirm that the baffle door is closed to prevent accidental air leakage. If you think about it, if you don't turn it off and suddenly a puff of smoke comes out, that's no joke.
In addition, clean up the accumulated dust around the old cloth, otherwise it will be dusty when you tear it down. If you have the conditions, use a vacuum cleaner to suck it, if you don't have the conditions, sweep it clean with a broom and wear a mask.
Remove the old cloth by hand-slow down, don't distort the flange
Loosen all the bolts first, but don't remove them all at once, leaving two diagonally. Why? Prevent the pressure plate from springing open suddenly or uneven deformation of the flange under force. Then start at the lowest point and use a crowbar to gently cock the platen up to pull the old cloth out. If the old cloth has become brittle and chipped, beware of debris falling into the flue, it is best to vacuum it clean. And guess what? A customer didn't pay attention when he dismantled it, and the debris fell in and blocked the pipeline behind it. As a result, it was shut down for three days to clean up, which was a big loss.
Don't throw the removed cloth, save the hole position and lap edge for comparison with the new cloth. Especially for overlapping edges, the design of each family may be different, some need to overlap 10cm, and some only need 5cm. It is most accurate to use old cloth as a template. If the old cloth is rotten and out of shape, use a tape measure to measure the distance from the flange edge to the bolt hole and keep a record.
Put on a new cloth-this is the test of patience
First lay the new cloth flat and cut it according to the shape of the old cloth, leaving 5-10cm margin. Note that the direction of the fiber of the cloth should be consistent with the flow direction of smoke. Usually, the manufacturer will mark the arrow on the cloth, so don't turn it backwards. I once saw a master install the arrow backwards, and as a result, the cloth was torn by the airflow within a few days of running-the direction was reversed, and the stress was all concentrated at one point. How long do you think it can last?
Align the flange hole and stick the cloth in it. Note that the overlapping edge of the cloth should be placed on the upstream side of the smoke, so that the overlapping edge can be pressed tightly by pressure, and it is not easy to leak. Then install the pressure plate back, install four corner bolts first, then install the middle bolt, and tighten diagonally 2-3 times. Don't screw to death at once, it will easily wrinkle the cloth. The torque is controlled at the recommended value of the manufacturer. If there is no data, you can twist the wrench by hand and it feels difficult to turn it for half a turn. Too tight will crush the fibers, too loose will leak air.
If it isRectangular non-metallic expansion joint, the position of the four corners is particularly easy to leak, so check more. The platen should be flattened and not warped. After the installation is completed, check between the pressure plate and the flange with a gauge, and the gap does not exceed 0.5mm before it is considered qualified.
Check after installation-don't rush to turn it on
Turn the car manually or pump it with compressed air to see if there are any air leaks. It is enough to control the compressed air pressure at 0.1~0.2MPa. If it is too large, it will easily burst the new cloth. Brush with soapy water on the edge of the platen and the lap seam. If there are bubbles, it will be the leakage spot. Check again whether the expansion joint has bulge and wrinkle, and whether the displacement is normal. If it isRectangular non-metallic expansion jointIt also depends on whether the four corners fit tightly. Once you find any wrinkles, loosen the bolts and readjust them immediately. Don't think of "turning it on first and trying it". It will be more troublesome if something goes wrong later.
Finally, recoveryDesulfurization flue gas baffle doorTo the normal state, start and run for half an hour, and check again. Focus on whether the cloth surface expands evenly and whether there is local overheating after the temperature rises. Touch the cloth surface temperature with your hand. If a certain area is obviously high, it means that the displacement compensation is not enough, and you need to adjust the tie rod or check the installation.
Routine maintenance recommendations-new cloth can last two more years
As the saying goes, three parts pack and seven parts feed. Check the cloth surface once a month for scratches and aging cracks. Don't wait if you find small damage, stick it with special repair tape. Note: Ordinary adhesive tape can't bear acid gas, so corrosion-resistant repair tape must be used. From our stationNon-metallic expansion joint (fabric fiber expansion joint)There are matching repair kits, so don't buy them randomly.
Tighten the bolts again every year when the machine is down, as thermal expansion and contraction can cause loosening. Especially for cloth that is more than one year old, the bolt torque may drop by more than 30%. In addition, there are many acidic gases in the desulfurization flue. If your cloth is not an acid-resistant coating version, it is recommended to replace it in advance. Think about it, it only takes half an hour to check once a month, and it costs thousands less to change the cloth and accessories with labor. Which one is cost-effective?
If the site hasDesulfurization flue gas baffle doorUsually, be careful not to let the door panel scrape the expansion joint cloth when opening and closing. Some baffle doors are not tightly sealed, and the leaked smoke will directly corrode the cloth surface. Check the sealing strip of the baffle door regularly and replace it when you need to.
Okay, have you remembered all the 5 steps from disassembly to installation, plus routine maintenance? Next time you encounter the aging and damage of the expansion joint cloth of the desulfurization flue, don't panic. Follow this process, and you can do it yourself. If you are really unsure, we also have technical support in our station, you can consult at any time.