How bad is the working environment of slag chiller drop pipe?
Slag chiller drop pipe-it sounds like a hard stubble post. It is common for slag to have a temperature above 800℃. High-temperature slag particles smash down at a speed of more than ten meters per second, and the pipeline keeps shrinking due to heat expansion and cold. You tell me, how many days can a normal bellows last when it is installed?
The metal expansion joint is not a general compensator here. It has to be pressure-resistant, wear-resistant and temperature-resistant. To put it bluntly, it is a 'hard bone' component. Before the selection, you don't understand the working conditions thoroughly, and then you will change the tube to cry.
Why is the expansion joint of slag drop pipe old and bad? Two killers
The number one killer – the heat. The slag at 800 ℃ directly burns the bellows, and the ordinary stainless steel is instantly oxidized and peeled off. The second killer-high-speed scour of particles. The slag particles grind the pipe wall like a grinding wheel. As soon as the guide tube is worn through, the bellows is directly exposed to the slag flow, and it is scrapped in a few minutes. And guess what? Two days ago, I met a friend from a power plant, saying that the general-purpose corrugated expansion joint they used leaked five times in three months, and the shutdown loss was more than 100,000 yuan.
So, don't fool things with generic models. For such conditions, products with wear-resistant liners or special structures are used. Like the one on our stationHigh temperature axial expansion jointAndLarge diameter thick wall expansion jointIs specially designed for this kind of scene. The wall thickness of the bellows is increased, and the guide tube is lined with wear-resistant layer, which can bear it.
Calculation of compensation amount determined by installation position
The drop pipe is usually arranged vertically, and the thermal expansion is mainly axial-this is known to everyone. But here's the problem: equipment vibration brings a small amount of lateral displacement, as well as angular displacement. You only count the axial compensation, ignore the angular displacement, the local stress of the bellows exceeds the standard, and it will crack sooner or later.
What about that? See the actual displacement type. If the lateral displacement is obvious, you can selectCompound hinge transverse expansion jointIt is very good at absorbing lateral displacement; If the pipe pressure is high and balanced thrust is required,Straight pipe pressure balanced expansion jointMore appropriate. Don't slap your head, first calculate the displacement of the pipe system.
How do materials and structures match?
Stainless steel 321 or 316Ti is the first choice for corrugated pipe material, which has good intergranular corrosion resistance and is not easy to embrittle at high temperature. What about the deflector? It has to be thickened! Even surfacing wear layers. High-temperature slag particles flow inside the slag drop pipe. Once the guide tube is worn out, the bellows is directly exposed to the slag flow-it will be scrapped in a few minutes. There is a special article in our FAQSpecific Function of Expansion Joint Guide TubeIt is very clear in it: the guide tube not only diverts the flow, but also is the body armor of the bellows.
In addition, the thickness and material of the guide tube should be designed according to the hardness of slag particles, so don't save that cost. The money saved isn't enough for one downtime loss.
On-site installation and maintenance cannot be saved
The metal expansion joint of slag drop pipe is generally equipped with a tie rod or a limit device, the purpose is to prevent excessive stretching during installation. Always adjust the tie rod nut according to the instructions during installation (refer to FAQHow to adjust the tie rod nut of expansion joint）。 Also, the transport screw must be removed before operation-an issue that is also highlighted in our FAQ (Do you need to remove the screw of the expansion joint）。 If it is not disassembled, the expansion joint cannot expand and contract freely, and the weld will be directly cracked by hard pulling.
What about overhauls? Don't wait for a leak to replace it. Check the lining for wear regularly, using a thickness gauge or endoscope. Slag cooler shuts down and loses tens of thousands of dollars at a time. Are you willing to risk those hundreds of dollars of lining money?
To summarize
The metal expansion joint of slag drop pipe of slag cooler is not a standard part, and must be customized according to the working conditions. Grasp three points when selecting a model- -High temperature grade, wear scheme, displacement type。 The high temperature level determines the material and structure of the bellows, the wear resistance scheme determines the thickness and lining of the guide tube, and the displacement type determines the structural form of the expansion joint (axial type, hinge type, pressure balance type, etc.). If you have any questions, ask the manufacturer directly, don't pat your head to select the model. Professional matters are handed over to professional people. This sentence is true in the slag discharge system.