auto-ignition temperature of diesel

[hairspray]

Hi, I work with a project of using diesel to run a pig through a pipeline offshore in the northern sea. I know the auto-ignition temperature of the diesel we want to use is 450 deg C, . It is a possibility that the pressure in this pipeline will increase to a 100 barg. Will this change the auto ignition temperature by the change of pressure??
Thank you

Ann Elisabeth

 

[25362]

Are you sure the given AIT of diesel is not in degrees Fahrenheit? Besides, may be thread71-85836 and thread798-89295 are helpful.

 

[hairspray]

Thank you, i will look into the other treads. Yes the self- igniton temperature is in degrees celcius...well the safety data sheet is saying that....

cheers

 

[25362]

I referred to the given AIT of 450^oC, which seems much higher than normal by about 200 degrees Celsius. The normal would be around 450K or, alternatively, around 450^oF.

See:

http://hypertextbook.com/facts/2005/EileenTang.shtml

 

[hairspray]

thank you!!!
I need to take this further, and discuss the reliability of the datasheet used for this project. U re right, it looks like it must be in Fahrenheit. The change of units is a dangerous thing in this business

cheers

 

[CJKruger]

While I agree the autoignition temperature for diesel is less than 450 C, it is more than the 210 C listed in the link. Boiling diesel will smoke, but I have not heard about it catching fire on its own.

For autoignition of diesel, my guess would be about 300 C plus or minus 50 C.

For info, autoignition is strongly dependent on chain length and aromaticity.

 

[25362]

Diesel engines are characterized by high-compression (of air) and self-ignition (of the fuel).

CJKruger is right on the basic chemistry factors, but there also other such as catalysts, additives, degree of atomization or vaporization.

Depending on grades of diesel, cetane numbers greater than 40 may be specified. Cetane's AIT is 210^oC. See

http://en.wikipedia.org/wiki/Cetane.

 

[hairspray]

cetane number is 45. That tells me that my diesel has under half the chance to self-ignition than hexadecan (which is the reference)?? Am I right?
And it looks like I should focus more on the chain length and aromaticity of the diesel, than the pressure change in the pipeline?

Thank you both for ure time

 

[CJKruger]

Here is some data to show how much autoignition varies for similar boiling points and number of carbon atoms:

C16H34, n-hexadecane
Boiling point = 287 C
Autoignition = 202 C

C16H26, pentaethylbenzene
Boiling point = 277 C
Autoignition = 293 C

C16H18, 1-(4-ethylphenyl)-2-phenylethane
Boiling point = 292 C
Autoignition = 673 C

 

[25362]

Better concentrate on the process of air heating by compression.