Pumping high melting point viscous fluid - any experienced advice?

[guerky]

I'm designing a new pumping system for a relatively high melting point (72°C) and viscosity (6.600 cP) through a 90m, 2 in SS316L line, with ambient temperatures that can get to -5° on some nights in the winter.
The fluid can be heated up to 100°C without any degradation. I intend to heat the fluid up to 93°C, to allow a higher temperature in the steam traces (3 kgf/cm² saturated steam) without risking an overheating in the line during the transfer.
This kind of fluid was tradiotionally handled in my company through a "tank-pump" (the product is melted in a hot bath, sucked with vacuum through a short hose to a pressure vessel and pumped through nitrogen pressure (3 kgf/cm², tipically)), in lines insulated and heated with spiral steam tracing.

I know from the operating personal that this kind of operation became a sort of paradigm due to failed experiences with pumps in the past in similar aplications. Despite being an inexperienced Process Engineer i refuse to just acept that a jacketed internal gear pump + a well insulated line (even with the simple spiral steam traces) couldnt handle it if some precautions to avoid fluid stagnation in the lines between batches are taken.

I've done my insulation calculations. There isnt any aparent problem.
The internal gear pump seems like an apropriated choice for pumping this viscous fluid, as high flow rates are not crucial.

So, i ask you for some experienced advices and, if possible, tips about some cost effective line heating and pumping technology.

Best Regards


In God we trust. All the others must bring data.

 

[georgeverghese]

If this fluid thermally degrades beyond 100degC, maybe better to go for electrical heat tracing as it enables more uniform pipe heating with self regulating style cables (no hot spots)in comparison to steam tracing.

Viking make gear pumps with integral casing heating elements that would be an alternate to these jacketed pumps. A plan 53 seal arrangement with barrier fluid / double seals will avoid messy spills to grade.

 

[guerky]

georgeverghese,

First, thanks for the tips.

"jacketed gear pump" was a poor translation (i'm Brazilian). I meant exactly this kind of pump (we already have one handling a very high viscosity fluid; many times more expensive than the standard cast iron external gear pump, but worth every penny).

About those electrical heat tracing, I must handle flammable liquids on the vicinities. Can't guarantee the safety against sparks, i guess.

In God we trust. All the others must bring data.

 

[georgeverghese]

Vaguely recall self regulating is good for Zone II classified areas (at least) - you could check with Thermon if this of interest. General literature indicates this is more reliable than steam tracing also.

 

[moltenmetal]

Luwa, not Lewa, makes gear pumps for really high viscosities- i.e. molten polymers. But your stuff is pretty modest- a fairly ordinary gear pump should do the job. Viking, Zenith and numerous others.

Yes, you can use electric tracing in a hazardous area- division/zone 2, not normally hazardous but hazardous in the event of a leak. Briskheet, Raychem, Thermon and numerous others make Div 2 rated power limiting and self-regulating cables. Limited maximum temperature in the 200 C range, but you only need 100 C so you'd be fine. Above that you're into mineral insulated heat traces, which can also be used in classified areas but you then run into issues associated with autoignition temperatures- MI cables can get VERY hot.