MDEA Viscosity

[Canoman]

I've been looking for some data on MDEA viscosity at low temperatures. As of yet, the lowest temperature that I have found any data for is 32°F. I want some data so that I can show the need for steam tracing piping through which pure, or almost pure, MDEA flows. The ambient temperature can easily reach 0°F in the winter at this location, yet the client does not see the need for steam coils in the storage tank or for tracing the line and pump.

Does anyone know where I could find viscosity data for MDEA below 32°F?

Thanks.

 

[TD2K]

I've taken a look around here but I don't seem to have much on viscosity of pure MDEA. Have you talked to Huntsman, they make the stuff.

My guess is that this stuff would be solid at 0F. Are you planning on installing a screw pump?

 

[Canoman]

I tried to call Huntsman yesterday, but their office was closed. I will try them again today. I also tried Atofina, but caught them after office hours as well. I did talk to someone at Dow/Union Carbide. He only had information down to 32°F.

BR&E TSweet only goes down to 32°F. HYSYS/AMSIM only goes down to 77°F, and it only does amine concentrations of 0 wt% - 50 wt%.

The freezing point of pure MDEA is -6°F, but it lowers considerably when water is added. At 60 wt% and 32°F, the viscosity is 65.4 cP. At 80 wt%, it's 337.7 cP.

It looks like I'll just have to try to make an educated guess based on what information I do have. I

 

[pronab]

Viscosity of MDEA : 101.0 cP @ 20 deg C.
33.8 cP @ 40 deg C.

 

[Canoman]

I'm looking for the viscosity at -17.778°C (0°F). Thanks for the input, Pronab, but that's not at a low enough temperature.

 

[freda]

For newtonian fluids Andrade's equation is useful for estimating viscosity at a temperature.

u = AL exp BL/T

From two known values of viscosity constants AL and BL can be determined
BL = (T1 * T2 * ln(u1/u2))/(T2 - T1)

AL = u1/exp (BL/T1)

Where T is absolute temperature

Using the 2 points provide by pronab the viscosity at 0F comes out to about 1275 Cp I think.

 

[Canoman]

Freda,

Thanks for the equation. Can you tell me where you found information on that? I checked the index of my Fluid Mechanics book from college, but couldn't find it there. Is this in Perry's?

 

[freda]

Canoman,

Flow Measurement Engineering Handbook by Richard W. Miller.

 

[pronab]

Freda / Canoman

Andrade corelations is used at low temperature , when
Tr~ 0.75 ( Reduced temperature = Tc/T). However I found constant AL and BL are : -5019.5 and 21.74 respectively. With this constant and @0 deg F(-17.77 Deg C) viscocity of MDEA coming 7.806 cP, which is not matching.I believe it is due to Tr>0.75(using 20 & 40 deg.C). I don't have the value of Tc for MDEA.
Freda can you help me how you calculate and get the MDEA viscosity @ 0 degF ( 1275 cP).
For Andrade corelations one can get it from PERRY Handbook;6th edition;p:3-281.

Regards to all.

Pronab Mistry.

 

[25362]

Whether MDEA behaves as a newtonian fluid or not near its freezing point is an issue to be clarified.
Anyway, using the BP chart that gives kinematic viscosity in cS vs temperature based on the relation loglog(v+0.8)=f(t) where v is in cS and t is absolute temperature, and taking published densities to convert cP to cS and viceversa, one gets 3000 cS at 0^oF or 3210 cP. Same result was obtained by using ASTM D341 chart for petroleum products.