I've had a murderous little service come up I have a few manufacturer's working on, thought I'd see if anyone has any added suggestions;
Basic service is a pump which serves to maintain a minimum flow in a free-water knockout at the inlet of a tarsands bitumen facility. The pump itself recycles a rag layer which forms between the water and bitumen layers at the outlet end of the drum, and discharges back to the drum inlet. The rag layer is a 'milkshake' consistancy emulsion of bitumen, water, entrained vapour, and fine sand at 1200 kPag, temperatures ranging from 135 to 200°C, and viscosities upwards of 300 cP at a flowrate of 60 m3/hr against a differential of about 200 kPa, with an NPSHA of about 3 meters.
Just to make things even more interesting, we need to avoid high-shear pumps like conventional centrifugal impellers because we want to avoid tightening up the emulsion that already exists in the rag layer.
First thing that came to mind was a progressing cavity pump, but even high temperature elastomeric stators wouldn't hold up for more than two or three weeks of continuous operation. I do have a PCP manufacturer looking into the temperature range of a line of steel stator PCP's they carry, but they typically rely on a higher viscosity fluid to seal the rotor & stator, since no interference fit is possible.
Another construction I'm looking at is a centrifugal screw pump - should have minimal impact on the emulsion and can easily pump the multi phase rag layer, but the upset temperature of 200°C is pushing the limit over where they're normally run - the manufacturer's I've contacted are still looking at means of achieving that temperature.
I've also looked into hydrocyclone type froth pumps, but despite their froth handling capability, at the bottom of the pump is a centrifugal impeller, which is going to tighten up the emulsion.
Right now it's starting to look like my best bet may be a multi-phase twin screw pump, (assuming the steel stator PCP and centrifugal screw options don't pan out) but the thought of four mechanical seals makes me cringe if there's any alternatives out there.
Any ideas?
Basic service is a pump which serves to maintain a minimum flow in a free-water knockout at the inlet of a tarsands bitumen facility. The pump itself recycles a rag layer which forms between the water and bitumen layers at the outlet end of the drum, and discharges back to the drum inlet. The rag layer is a 'milkshake' consistancy emulsion of bitumen, water, entrained vapour, and fine sand at 1200 kPag, temperatures ranging from 135 to 200°C, and viscosities upwards of 300 cP at a flowrate of 60 m3/hr against a differential of about 200 kPa, with an NPSHA of about 3 meters.
Just to make things even more interesting, we need to avoid high-shear pumps like conventional centrifugal impellers because we want to avoid tightening up the emulsion that already exists in the rag layer.
First thing that came to mind was a progressing cavity pump, but even high temperature elastomeric stators wouldn't hold up for more than two or three weeks of continuous operation. I do have a PCP manufacturer looking into the temperature range of a line of steel stator PCP's they carry, but they typically rely on a higher viscosity fluid to seal the rotor & stator, since no interference fit is possible.
Another construction I'm looking at is a centrifugal screw pump - should have minimal impact on the emulsion and can easily pump the multi phase rag layer, but the upset temperature of 200°C is pushing the limit over where they're normally run - the manufacturer's I've contacted are still looking at means of achieving that temperature.
I've also looked into hydrocyclone type froth pumps, but despite their froth handling capability, at the bottom of the pump is a centrifugal impeller, which is going to tighten up the emulsion.
Right now it's starting to look like my best bet may be a multi-phase twin screw pump, (assuming the steel stator PCP and centrifugal screw options don't pan out) but the thought of four mechanical seals makes me cringe if there's any alternatives out there.
Any ideas?
