Anyone experience excessive erosion wear (pumping a heavy sand slurry) on slurry pump suction liners. We had been testing a urethane product with great success, then changed the discharge piping from 20" to 24" diameter and reduced our suction liner wear from 52 weeks to 4 weeks. Process conditions have not varied that much. Any comments would be appreciated. Pumping a slurry density of 1.4 gms/ml, 16000 usgpm, discharge pressure of 300 psig.
Sounds odd - but a good opportunity to play detective.. Are you at the same fluid flow with the larger diameter discharge pipe? What kind of pump are you using - (I'm assuming a diaphragm pump) What is the solids loading? What is the wear pattern? If the fluid velocity decreased you could get partial settling in the pipe. The increased solids at the bottom of the pipe may not be enough to cause clogging, but it might increase the solids enough so slurry becomes dilatant during part of the pumping cycle - increases wear. If you increased the fluid flow with the larger diameter outlet, the slurry may be experiencing shear rates in the dlatant regime during the pump cycle with out any settling. Or - depending on your answer to the initial 4 questions - none of the above.
If I have sorted your wired units out you seem to have a rather high flow rate, probably a change in flow type, due to the reduced velocity.
Flowrate is the same -hasn't changed, but velocity in discharge piping dropped off dramatically (22 to 13 ft/sec). We are using a GIW TBC46 slurry pump. This train of 5 pumps tends to get more 2" rocks than the other 4 trains due to feed distribution issues. The density tends to be somewhat lower on this train for this reason as well - 35 to 40% solids loading. We too are thinking we are experiencing settling of the larger rocks which tends to cause a build up of backpressure on the pumps - sort of like plug flow.
Not sure what we can do about this, aside from going back to the 20" diameter pipe (approximately 100 ft). We went to the larger diameter to reduce the wear that we have been seeing on the pipes.
Some thoughts were to try a white iron suction liner to minimize the gouging wear that we are seeing on the urethane liners. Another option would be to install a short reduced section of pipe ( say 10 feet) of 20" to allow free flow. Not sure what other options we could try?
The diameter of the discharge line was increased by 20% (44% increase in pipe cross-sectional area), and at the same time the life on the liners in the intake line (suction line) decreased from
52 weeks to 4 weeks. Is this the correct recap of the above?Why was size of the discharge pipe increased? Did this increase the discharge rate? If the discharge rate increased then the flow velocity in the intake line had to increase, and this may explain the increased wear.
Regards,
Ernie
- The 20" inch diameter didn't register the first time I read it. - is this possibly for a mining or dredging application? - just curious It sound like you have a good idea as to what may be happening - I was fortunate enough to never have had to deal with 2" rocks in a slurry. It sounds like a tough problem to cure inexpensively. For high wear applications I've seen some chrome coatings used quite successfully in pipes with abrasive slurries and to coat the interior liner of horizontal bead mills. Chrome coatings can be expense if you can't find a low cost specialty coater and when the chrome wears through - the rest of the unit soon follows. I vaguely remember talk of using cryogenic steel for some high wear applications (the cost was not bad and the wear resistance was excellent) I'll try to contact some old co-workers to see if they have any info that could help
Good luck, Gregg
The recap is correct. We wanted to go to a larger diameter discharge pipe because of high wear on the 20" - seeing 20 to 25 ft/sec in pipe. Now velocity is 13 ft/sec - less wear on pipe. But since the rocks are more evident on this line, wasn't aware of this before, it is probably settling out at these lower velocitys. We are currently using chrome carbide overlays on mild steel pipe but they too will wear out fast if the velocity is high. The 2" rocks also tend to damage the overlay when the rock comes in contact with the wall of the pipe, especially at lower pumping densities.
Yes, we have been using a chrome carbide overlay in all of our high abrasive slurry applications. Have even tried tunsten overlay at the flanges where wear is more prominent if pipes are not lined up properly. We are also experimenting with some urethane lined pipe. I would be interested in hearing more about the cryogenic pipe.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.