We have had problems in our WWTP with recurring wear on our stators (replaced monthly) and rotors (replaced every 3 months). This is on a cavity pump that pushed dewatered digested sludge over 160 m through DN 200 (NPS 8) at 30 bars of pressure. After analyzing the sludge, it turned out that struvite (phosphate precipitate from digestive process) was eroding the stator. Using a struvite dispersant, we have extended the life of our stator by 6 months.
In your case, the phenomenon may have two causes:
- Presence of abrasive particulates in your industrial sludge
- Incorrect pressure during compression stage, which could be rectified by installing a manometer/pressure gauge to determine how much pressure is actually being exerted. Check with your pump supplier to verify the proper flow/pressure ratio.
If you inject a polymer via a flange on the delivery pipe to the pump, you can reduce head loss almost twofold (polymer dose of 15 to 25 L/h for 1000 kg wet sludge/h).
If you have foreign or abrasive substances in the sludge, there is another solution we looked at for our plant: a double-piston Putzmeister-type pump with charging line, but it is extremely expensive…and probably way more than you need for your installation.
Here is a link to the single-piston pump: