Heavy Crude Properties 2

[sistermjensen]

Can anyone help me estimate viscosity, specific heat and thermal conductivity for heavy crude oils? I need to do some flow simulations and evaluate fluid cooling due to ambient temperatures. I'm looking at a variety of heavy crudes - say from about API 20 down to API 12. I just need typicals, and am really struggling to find anything. Help!

 

[SNORGY]

I think I might have the data that you are looking for. It is a table of exactly those properties for typical crude oils from API 0 thru API 26 for temperatures between 10 F and 500 F.

I have no idea where I originally found it, but the dilemma I have is that there is text at the bottom of each page that says:

"PROPERTY OF COMBUSTION ENGINEERING TULSA OKLAHOMA. DO NOT COPY."

So, I appear to be faced with an ethical dilemma. It is a very old table of values, but perhaps you could contact Combustion Engineering in Tulsa, Oklahoma and see if they would permit disclosure of that or other data?




Regards,

SNORGY.

 

[BigInch]

I think you mean VERY heavy.

Tip:

The flow properties of crude petroleum having an API gravity varying from about 6 to 12 are improved by heating the crude petroleum to a temperature of about 35°C to 200°C and, in the presence of a suitable viscosity reducing additive, shearing the heated crude petroleum with a high shearing force sufficient to reduce the viscosity of the crude petroleum to a range of about 250 centipoise (cP) to about 1000 cP. Suitable viscosity reducing additives include gasoline, naphtha, butanol, petroleum ether, diesel fuel, citrus oil based cleansers and degreasers, and mixtures thereof.

Blending:

In general, the amount of viscosity reducing additive can vary from about 15 weight % to about 50 weight %, and preferably about 20 weight % to 35 weight %, of the petroleum crude. About 20 weight % to 35 weight % of gasoline and/or light naphtha is sufficient to reduce the viscosity of the petroleum crude to less than about 600 cP to less than about 400 cP at 35°C.

Heat Capacity 0.47 Btu/Lbm-F

Be careful with these. There can be a lot of variance.


API gravity at 60/60°F
°API 21.3 18.3 15 14.1 14.8 11 9.3 4.5
40°C cSt 40.3 370 850 12000 2640 3000 19000 8.56E+12
50°C cSt 25.3 181 3900 1030 3.11E+11
60°C cSt 16.9 99.0 1500 470 700 6.24E+08
100°C cSt 5.22 18.2 45 125 55.4 252 163000
135°C cSt 2.64 7.15 33.7 18.5 5595
180°C cSt 0.00 11.2 7.32 475

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[sistermjensen]

Thank you so much! This helps a lot. The only other piece I could use is the Thermal conductivity.

Snorgy - I checked around to see if I could find Combustion Engineering in Tulsa OK, and it appears they aren't in business any more. I appreciate your ethical concern - and honor it.

Thank you!

 

[BigInch]

Thermal conductivity by the Cragoe Equation,
BTU/HR/FT2/(ºF/INCH)
= 0.813 / SG60 * (1-0.003 * (Temp_deg_F - 32))

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[BigInch]

The tricky part is evaluating the convective heat transfer coefficient at the oil film and pipe wall interface in the calculation of the overall heat transfer coefficient.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[SNORGY]

Sistermjensen:

Thanks. Maybe this data that I have can be considered public domain, then? Alternatively, I might be able to find a similar table.

It's *really frustrating* because I know I have in my possession exactly the data that you want.

Let me know if you have found everything that you need and if I can help further.

Regards,

SNORGY.

 

[BigInch]

Well....

Snorgy,

Could at least you comment as to how my values compare with your secret data?

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[sistermjensen]

Hey BigInch,

I am struggling to convert the Cragoe Equation you provided. I'm not sure I have the parenthesis correct. Is it:
BTU/HR/FT2/(oF/INCH) = 0.813/(SG60 x (1-(0.003 x (oF - 32))))
or
BTU/HR/FT2/(oF/INCH) = 0.813/(SG60 x (1-0.003) x (oF - 32))
or
BTU/HR/FT2/(oF/INCH) = (0.813/SG60) x (1-(0.003 x (oF - 32)))

Also, Specific Heat (Cp) of 0.47 Btu/Lbm-oF converts to 319.05 Lbf Ft/Lbm oF. Can that be correct?

Thank you!

 

[SNORGY]

BigInch:

Data that I have suggests a range in Cp = 0.41 to 0.45 over the same temperature range for almost (but not quite) equal API gravities. As for the viscosities in cSt, there is rather fair to poor correlation with the values I have.

For example:

18 API oil cSt at various temperatures:

40 C = 104 F => 250 cSt
50 C = 122 F => 130 cSt
60 C = 140 F => 79 cSt
100 C = 212 F => 18 cSt
135 C = 275 F => 8 cSt
180 C = 356 F => 3 cSt

14 API oil cSt at various temperatures:

40 C = 104 F => 939 cSt
50 C = 122 F => 475 cSt
60 C = 140 F => 271 cSt
100 C = 212 F => 49 cSt
135 C = 275 F => 18 cSt
180 C = 356 F => 7 cSt

Regards,

SNORGY.

 

[BigInch]

Cut and paste Cragoe equation into Excel exactly as it appears in my formulation above, ie. operation priority default is left to right.

Snorgy, thanks. Good to poor correlation would be normal, depending on wax contents and even the state of the crude when measured. The composition can be quite different among various crudes, giving the same average density, but different viscosities. And even, if they've been recently pumped, maybe 20% less than those that have sat around. Viscosities can easily get into nonNewtonian values too.

My table above didn't format too well in html. I think you have to cut and paste to get the right table format. Just in case that doesn't work, here's the table again with placeholders for the missing data.

°API 21.3 18.3 15 14.1 14.8 11 9.3 4.5
40°C cSt 40.3 370 850 12000 2640 3000 19000 8.56E+12
50°C cSt 25.3 181 --- 3900 1030 ---- ----- 3.11E+11
60°C cSt 16.9 99.0 --- 1500 470 700 ----- 6.24E+08
100°C cSt 5.22 18.2 45 125 55.4 ---- 252 163000
135°C cSt 2.64 7.15 --- 33.7 18.5 ---- --- 5595
180°C cSt 0.00 ---- --- 11.2 7.32 ---- --- 475

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[sistermjensen]

Snorgy and BigInch - you guys are the BEST. Thank You!

 

[BigInch]

Cheers.

Beware, depending on temperature profile, you could have turbulent flow at the beginning of the pipeline and laminar flow at the end.

Good luck.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[SNORGY]

Sistermjensen:

I tried to put some of the data I had to a generalized DeGuzman-Andrade correlation of the form:

m = A*e^(B/T)

You take logs on both sides at two points and solve for A and B. I found that the correlation was rather poor even over fairly narrow temperature ranges due, presumably, to the non-Newtonian behaviour of multi-component mixtures that crudes - and their blends - are.

In light of BigInch's depth of knowledge and experience in this field, I would be inclined to take his approach.

Regards,

SNORGY.

 

[BigInch]

That would be, without specific labratory data, "stay conservative".. and on the high side of that.

Over long distances and mountainous temperature profiles, or winter summer/dry wet soil conditions where soil heat capacity varies greatly with water content, you may have turbulent flow at low elevations and laminar flow at high elevations, or v/v and similar induced transients. On some heavy crude pipelines you never ever actually reach steady state flow, because it takes too long for the flowrate to stabilize against constantly changing summer to winter environment temperatures and the changes to the soil heat capacities as the soil dries and moistens throughout the year. Sometimes the combinations interfere with each other and you just have permant flowrate cycle chasing. Like the highest temperatures in the northern hemisphere occur a month after midsummer in August, the pipeline maximum flows might be reached 3 weeks after that, in September when soil temperatures finally start cooling. If you design for maximum flow based on August temperatures alone, maybe you'll never reach that rate. Rainy seasons in winter make it worse, but in summer might help stabilize the cycles.

Shutdowns for one week, two weeks, a month can drastically affect the horsepower and the time needed to get up and running again at normal flowrates too. A week shutdown might take three weeks to reach maximum flows again.



**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[jmw]

Useful information BigInch, it always helps to gain some understanding of what actually happens out there in the real world.

With the heavier crudes, how common is adding "snot" ?

(Sorry, "snot" was what the pipeline engineers called the drag reducer, in an application on a multi-product pipeline unloading tankers, where they used a viscometer to identify the crude and thus allow dose pre-determined amounts of "snot" as appropriate to the specific crude).

JMW

http://www.ViscoAnalyser.com

 

[BigInch]

I've only run into that one time, just lately, and that was being proposed for a lateral off a main refined product pipeline, not crude. It seems to be expensive enough such that its the last resort used just before increasing capacity by looping a pipeline becomes necessary. But I obviously haven't seen enough of it to have formed a good opinion about it.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/