Special-shaped straight non-metallic compensator: What's so good about this thing?
Two days ago, a customer who was doing a desulfurization project called and asked, "Do you have a non-metallic compensator with a box shape and a straight structure?" My first reaction was a rectangular non-metallic expansion joint, but when I asked carefully, people wanted a straight type-that is, a non-metallic compensator with a square or rectangular cross section, a straight cylinder, no taper or special elbow. That's the same thing we usually doNon-metallic expansion joint (fabric fiber expansion joint)It's not the same thing. Special-shaped straight non-metallic compensator, to put it bluntly, is a flexible compensator with a pipeline section that is not circular, but keeps a straight line as a whole. It is used to absorb thermal displacement, reduce vibration and noise. Compared with the standard circular or rectangular non-metallic expansion joint, the design pays more attention to the adaptation of specific space and airflow direction.
Structural hinterland: fabric + rubber, how can a straight tube withstand high temperature and pressure?
The core of special-shaped straight non-metallic compensator is the word "straight cylinder". Its cylinder is made of multi-layers of temperature-resistant fabrics (such as silicone cloth and fluororubber cloth) and rubber composite laminated, with thermal insulation cotton sandwiched in the middle and a layer of corrosion-resistant polytetrafluoroethylene film covered on the outside. Why do you want to make it straight? Because many flue ducts and desulfurization pipes are square connected, a reducer has to be added with a circular compensator to increase pressure loss and air leakage point. Straight type direct butt welded flange with smooth flow path. However, the disadvantage of straight tube is also obvious-there is no elastic compensation of ripples, and it all depends on the elastic deformation and sliding between layers of fabric layer itself to absorb displacement. Therefore, its compensation amount will not be too large. Usually, the axial displacement of a single section is 30~50mm, and the lateral displacement is smaller. If you want to increase the amount of compensation, you have to connect it in series into a duplex structure with a guide tube in the middle-this is the same asCompound hinge transverse expansion jointThe idea is a bit similar, but the materials are completely different.
Application scenario: Who is using this stuff? Cement plant, power plant, desulfurization system
To be honest, the most popular place of special-shaped straight non-metallic compensator is the flue gas treatment system. For example, the rotary kiln tail gas pipeline in the cement industry has a large cross section, high temperature (often above 300℃), and the medium contains sulfur and dust. With metal corrugated expansion joints? Corrosion problems can give you a headache to death. With rectangular non-metallic expansion joints? Rectangular products given by many manufacturers are actually special-shaped rings with corrugations, not straight tubes. The straight type is more resistant to wear because the inner wall is smooth and there is no dust accumulation in corrugated grooves. of power plantDesulfurization flue gas baffle doorBefore and after,Round Flap Door (Double Seal)This straight square tube compensator is also often needed. Additionally, air-cooled island vacuum duct systems are occasionally used-but there are moreDouble hinge expansion joint for air-cooled island vacuum pipelineWithout expanding. And guess what? Some fan outlet pipes use straight non-metallic compensators, and the on-site noise is directly reduced by 5~8 decibels, which is more effective than adding silencers.
How to do model selection? Temperature, pressure, displacement, one must not be less
If you want to choose a special-shaped straight non-metallic compensator, you must first go to the site to measure the length, width and wall thickness of the pipe section. Then calculate the medium temperature: ordinary silicone cloth can withstand 200℃, and fluororubber cloth can carry 250℃. If it exceeds 300℃, it has to be reinforced with ceramic fiber cloth + stainless steel wire mesh. In terms of pressure, generally, the withstand pressure of non-metals is 0.1~0.3MPa, low-pressure systems are fine, and high-pressure pipelines have to honestly wear metal expansion joints-such asUniversal corrugated expansion jointOrHigh temperature axial expansion joint。 As for the displacement, I just said that a single section is not big. If the hot and cold displacement exceeds 50mm, it has to be made into a double structure with a guide tube in the middle. And the pH of the medium-with strong acids,PTFE-lined hoseOrPTFE compensatorMight be more appropriate. Don't push it hard, otherwise it will rotten for you in two months. Last year, a customer tried to save trouble and used the straight type on the pipeline containing concentrated sulfuric acid. As a result, the fabric layer was directly carbonized. Isn't the lesson profound enough?
Installation and maintenance: Don't underestimate flanges and deflectors
When installing a special-shaped straight non-metallic compensator, the most taboo thing is to screw the bolts. The flange surface must be flat, the gasket must be aligned, and the bolt must be screwed to the torque value-whoever cracks the fabric layer with too much force will come to you for air and ash leakage. In addition, although the inner wall of the straight cylinder is smooth, it is recommended to install a guide tube if there is high-speed dusty airflow washing. What does the deflector do? As written in the FAQ-protects the fabric layer from direct impact and also reduces flow resistance. Daily maintenance is mainly to check whether the outer cloth is aged and cracked, and whether the flange bolts are loose. If you find local damage, repair it quickly. Don't wait for the whole piece to tear before replacing it, which will delay the construction period and double the cost. By the way, if it is used inManual plug-in insulation doorOrElectric plug-in insulation doorNearby, remember to leave enough room for installation, and don't let the flange interfere.
Compared with a metal compensator, which one should I choose?
Depends on the working conditions. If the temperature exceeds 400℃, the pressure exceeds 0.5MPa, and the medium is oily or flammable or explosive, don't hesitate to put on a metal corrugated expansion joint-such asUniversal corrugated expansion jointOrHigh temperature axial expansion joint。 However, if it is low temperature and low pressure, large diameter and corrosive flue gas, the cost performance of special-shaped straight non-metallic compensator will beat metal-light weight, corrosion resistance, easy installation and simple maintenance. Moreover, the vibration isolation and noise reduction effect of non-metal is much better than that of metal. With this, the noise on the spot can be reduced by several decibels in fan ducts. So don't listen to people brag, suitability is the last word. If you are still unsure, you can check the information in the siteMetal rectangular expansion jointAndRectangular non-metallic expansion jointComparing it, you know what you know.