Issues regarding pump selection for scaling-prone media
Thread Content
Hey everyone: I’ve been active in this community for many years and work in equipment management. I’ve encountered an issue in production that I’m not sure how to resolve, so I’m hoping everyone can help me come up with some solutions. Thank you! The pump used in my facility handles a medium that consists of organic substances and alkalis. During normal operation, the temperature of the medium in the pump (a magnetic pump) is around 10 degrees, with an outlet pressure of approximately 12 kilograms. Due to the presence of alkalis, it is very easy for alkaline scale to form and accumulate inside the pump. So, it’s often necessary to clean the equipment (the impeller and volute need to be cleaned every about half a month). Shielded pumps have also been used, and it seems the situation is similar with them. Screw pumps have been tried as well, but due to the properties of the medium, the stator of the screw pump tends to swell; if it remains stopped for too long, starting up again can damage the fluororubber stator, so this option isn’t viable either. We’re considering using gear pumps, but since the medium has little viscosity, it’s likely that those won’t work either, and their efficiency would definitely be low. I wonder if any of you have any other pump types that might be suitable?
Analyzing the problem as stated in the question, it may be necessary to address this issue from the perspective of usage management. From the perspective of the usage cycle, a period of half a month could be when crystallization occurs during periods of downtime. If a pump-stop backwashing procedure is established, with a backwash being performed each time before starting up and after shutting down to reduce the likelihood of crystallization, this should increase the equipment’s service life. The key issue lies in the crystallization of the medium inside the pump after it stops operating; if this is the case, a clean water backwashing process should be implemented. Another possibility is the crystallization that occurs during the production process; it is necessary to determine whether heat-exchanging gas should be used before feeding in order to change the temperature of the medium and reduce its saturation level, thereby minimizing the likelihood of crystallization. For reference.
I don’t know about the other things you mentioned, but for a while we used arc gear pumps with copper impellers to pump gasoline into train cars, and there were no problems with the pumping volume; so I think the pumping capacity of the gear pump has little to do with viscosity. It was later discontinued because the skeleton oil seal leaked a small amount of oil, and once that oil got into the bearing, it damaged the bearing. The screw pump you are referring to is a single-screw pump, right? The stator of a twin-screw pump doesn’t have rubber in it.
What I have here is alkaline scale, which gradually accumulates on the impeller during operation; as a result, the outlet pressure slowly decreases. After a certain period of time, the flow rate can no longer be maintained, and cleaning becomes necessary. The methods used to reduce alkaline scale have already been tried, such as reducing the amount of alkali and acid fed in. Otherwise, cleaning was required every few days, and the pump was also prone to damage
I want to try using a gear pump first, but I’m not sure if it can achieve a flow rate of 5 cubic meters If gear pumps are viable, twin-screw pumps might also be usable
I’m not looking for a gear pump with a skeleton oil seal; one with a mechanical seal would be better, as those with skeleton oil seals tend to leak more easily
I wonder if any of you know of other types of mechanical pumps that are suitable for the working conditions and media I’m referring to. Are there any positive displacement pumps?
I’m not very familiar with your manufacturing process. Would it be better to heat the medium at the inlet? That way, even magnetic pumps would work fine. In our factory, magnetic pumps are used to transport alkalis, and they work just fine.
Could you tell me what temperature you heat it to? Pure alkalis pose no problem; we will generate alkaline scale such as NaF, which adheres to the impeller
I’ll check on this type of pump. May I ask what the flow rate of this pump can be?