Large diameter smoke duct stainless steel metal expansion joint, exactly what problem to solve?
Think about it, the temperature of the flue gas coming out of the boiler of the power plant is always three or four hundred degrees, and there are sulfide and water vapor in it. The thermal expansion and contraction of the pipeline can run out for tens of millimeters. Ordinary carbon steel compensator? The rust wore out in half a year. Non-metallic fabric compensator It will be powdered in two years at high temperature, and it will be a big trouble for the debris to be blocked downstream.Stainless steel metal expansion joint for large diameter smoke and air ductIt is specially designed to treat this kind of working condition-corrosion resistance, high temperature, displacement absorption, and no slag falling into the pipeline.
Power stations and cement plants are the main application scenarios
This thing is not used everywhere, but the power stations and cement industries are really spread out in large numbers. Which is not a large diameter from the flue from the boiler outlet to the desulfurization tower and the connection section from the preheater to the dust collector? DN2000, DN3000 and even larger. In our own products,Corrugated expansion joint for power station industryAndMetal Corrugated Expansion Joints in Cement IndustryIs a typical representative. But these alone are not enough-the pressure of the flue gas pipe is not high but the temperature fluctuates greatly, the wall thickness has to be increased, and the corrugated structure has to be recalculated, so it has to be upgraded toLarge diameter thick wall expansion jointThe design logic of. To put it bluntly,Stainless steel metal expansion joint for large diameter smoke and air ductIt is the master of products in the previous two industries, specializing in dealing with the harsh combination of large diameter, strong corrosion and high-frequency thermal displacement.
Why must stainless steel be applied to smoke ducts?
Alas, I have answered this question to clients no less than a hundred times. Carbon steel is cheap, but the little condensed water in the flue gas is enough for it to withstand. It is changed every two years, and labor is more expensive than materials.Non-metallic expansion joint (fabric fiber expansion joint)It is indeed corrosion resistant, but it is afraid of high temperature-it will start to age when it exceeds 300℃, and it is a matter of time before the fibers fall off.rubber compensatorNot to mention, when the temperature is high, it will become brittle directly. What about stainless steel? 304L is enough to deal with general smoke, and 316L with high chlorine content will not be bad for more than ten years. Moreover, the metal bellows itself has no polymer component, so it will not produce debris to block the pipeline-this is particularly important at the entrance of the desulfurization tower. If it is blocked for maintenance for several days, who can bear the shutdown loss?
Three parameters that cannot be avoided in model selection: caliber, temperature and pressure
Two days ago, I met a customer from a cement factory and asked, "I want a DN1200 corrugated compensator". I said don't worry, it depends on the temperature. The design temperature of his smoke duct is 380℃, but the actual temperature occasionally rushes to 450℃. Then ordinary austenitic stainless steel bellows have to consider the stress relaxation problem.Large diameter thick wall expansion jointThe idea is as follows: once the diameter exceeds DN1000, the wall thickness can't be measured according to the experience of small pipe diameter, and the pressure bearing capacity and fatigue life of the corrugation have to be calculated. Another overlooked is the deflector-we specifically talked about it in our FAQ,Specific Function of Expansion Joint Guide TubeIt is to guide the high-speed smoke into the pipe, so as to prevent it from directly washing the corrugated root. If you think about it, the flue gas velocity is 20m/s, with a little dust, and the root of the bellows can be ground out of grooves in a year. Once the guide tube is installed, the life time is doubled.
Installation and maintenance of pits, each worse than the last
And guess what? I have seen more than one construction site where the expansion joint was installed and the tie rod nut was not removed. As a result, once the pipe heated up, the bellows couldn't expand and contract, and the fixing bracket was crooked. Remember:Does the screw of the expansion joint need to be removed?The transport bolt (the locking nut on the tie rod) must be removed, otherwise the compensation will fail. What about the adjustment nut? That is used for pre-pulling or pre-pressing, and it should be adjusted to the design position after installation is complete. Don't turn the arrow in the opposite direction —The direction of the arrow of the expansion joint refers toThe flow direction of the medium, if the guide tube is installed opposite to the direction of the incoming flow, it will vibrate when the resistance is increased.
In addition, expansion joints in smoke duct systems are often used in conjunction with baffle doors. Such asRound Flap Door (Double Seal)OrDesulfurization flue gas baffle doorAs soon as the baffle door is closed during maintenance, the isolation section can work safely. Our ownDouble-sealed single-axis circular baffle doorIt is designed for this scene, with large-diameter expansion joints, a set of schemes to get compensation and isolation.
Really unsure? Take a look at the existing type spectrum
When you are hesitant to select, it is better than anything to flip through our existing product information. FromUniversal corrugated expansion jointToHigh temperature axial expansion jointAnd then toCompound hinge transverse expansion joint, basically covering common scenarios. Large-diameter smoke and air ducts generally choose axial type or double transverse type-the former absorbs the thermal elongation of straight pipe sections, and the latter should cope with the lateral displacement of L-shaped pipes. Which one to choose depends on the direction of the pipeline and the layout of the fixed bracket. For example, the main flue of the power plant is tens of meters long, with a guide bracket in the middle, so the axial type is enough; However, if there is a turn between the boiler outlet and the dust collector, you have to use the double transverse type, otherwise the bellows will be twisted.
At the end of the day,Stainless steel metal expansion joint for large diameter smoke and air ductNot some advanced technique, but the details make or break. If the material is selected correctly, the parameters are calculated accurately, and the installation is in place, there will be no problems in ten years.