10 replies to this topic

[NSF]

Hi,

Im trying to find the solubility of CO2 in crude oil, anyone here who can help me?

I have a tank with 3 barg pressure.

[ankur2061]

NSF,

Why is your post in the "Tank Blanketing and Venting" forum? Are you going to use CO2 for blanketing a crude oil tank? If so, then clarify further about the usage of CO2 as a blanketing medium.

We are a chemical engineering forum and not a forum for clairvoyants.

Post more details about what you want to do, so that we can interpret what you need.

Regards,
Ankur.

[NSF]

Ankur,

Yes, I'm going to use CO2 as a blanketing gas for crude oil tanks, thats why I posted in this forum. I don't know how you want me to clarify about the usage, since you, as you said, is a chemical engineering forum, you would know about CO2 as an inert gas.

Im transporting crude oil in tanks under 3 barg pressure, with CO2 as a blanket gas. I would like to know the solubility of CO2 in crude under these conditions. I can't give you much details about the system, but if you ask what you need to know, I'll answer. But isn't there a table or something to refer to? For now, I don't need a exact value, since this is a study and we don't know much about the crude yet.

Hope to not get as sarcastic answers next time, it is not as fun for new members...

[Qalander (Chem)]

Dear NSF Hello/Good Afternoon,

Don't get upset Just google 'CO2 solubility into crude oil for blanketting use' I've just done and got 2,930 hits.

Best of luck.
Regards
Qalander

[ankur2061]

NSF,

When you provide very vague details about your requirements, naturally people who read your posting are going to feel puzzled and disappointed by the inadequacy of the details.

You have not provided your system details nor have you provided a sketch for the person to interpret. Alright, let us get some more details about your CO2 blanketing system:

1. Is it an existing blanketing system or do you intend to provide a new blanketing system?

2. What blanketing pressure has been used or is intended to be used? This question is extremely relevant because the partial pressures of the system components will help in determining the solubility of CO2.

3. Is the tank MAWP & MAWV adequate to have a blanketing system?

4. How is overpressure relieved from the tank if the blanketing valve fails open or vacuum conditions avoided if the blanketing is not available?

5. Where is the crude oil tank vented - a) to atmosphere? or to a vapor recovery system?

6. What is the storage temperature in the crude oil tank? This is because the solubility is also a function of the temperature of the tank contents.

You must realize that when you have provided the above details, then only a proper response can be formulated. Engineering is based on inputs, a minimum number of correct inputs are required to provide an engineering response.

Hope you understand. BTW, my apology for being a tad too harsh.

Regards,
Ankur.

[Qalander (Chem)]

Dear NSF Hello/Good Evening,

Congratulations on very good and fairly adequate reply from Our friend ankur; but do request you to ensure better/accurate phrasing along with relevant data in all future queries.

Best regards
Qalander

[NSF]

NSF,

When you provide very vague details about your requirements, naturally people who read your posting are going to feel puzzled and disappointed by the inadequacy of the details.

You have not provided your system details nor have you provided a sketch for the person to interpret. Alright, let us get some more details about your CO2 blanketing system:

1. Is it an existing blanketing system or do you intend to provide a new blanketing system?

2. What blanketing pressure has been used or is intended to be used? This question is extremely relevant because the partial pressures of the system components will help in determining the solubility of CO2.

3. Is the tank MAWP & MAWV adequate to have a blanketing system?

4. How is overpressure relieved from the tank if the blanketing valve fails open or vacuum conditions avoided if the blanketing is not available?

5. Where is the crude oil tank vented - a) to atmosphere? or to a vapor recovery system?

6. What is the storage temperature in the crude oil tank? This is because the solubility is also a function of the temperature of the tank contents.

You must realize that when you have provided the above details, then only a proper response can be formulated. Engineering is based on inputs, a minimum number of correct inputs are required to provide an engineering response.

Hope you understand. BTW, my apology for being a tad too harsh.

Regards,
Ankur.

Ankur, thanks for your answer.

1. This is a ship rebuiling, so the systems are all new
2. Blanketing pressure of 3 barg (is this what you ask?)
3. MAWP = 6 barg, tank desing pressure is 7 barg
4. and 5. The tank is provided with safety valves to atmosphere, and vapour recycling system with heating and a gas cooling plant.
6. Crude temperature 40 degrees Celsius

The system is not finished yet and is beeing worked on. Unfortunately, I cant provide you any sketches. I must emphasise that this is a preliminary study, not a project to design.

Regards Nina

[Qalander (Chem)]

NSF,

When you provide very vague details about your requirements, naturally people who read your posting are going to feel puzzled and disappointed by the inadequacy of the details.

You have not provided your system details nor have you provided a sketch for the person to interpret. Alright, let us get some more details about your CO2 blanketing system:

1. Is it an existing blanketing system or do you intend to provide a new blanketing system?

2. What blanketing pressure has been used or is intended to be used? This question is extremely relevant because the partial pressures of the system components will help in determining the solubility of CO2.

3. Is the tank MAWP & MAWV adequate to have a blanketing system?

4. How is overpressure relieved from the tank if the blanketing valve fails open or vacuum conditions avoided if the blanketing is not available?

5. Where is the crude oil tank vented - a) to atmosphere? or to a vapor recovery system?

6. What is the storage temperature in the crude oil tank? This is because the solubility is also a function of the temperature of the tank contents.

You must realize that when you have provided the above details, then only a proper response can be formulated. Engineering is based on inputs, a minimum number of correct inputs are required to provide an engineering response.

Hope you understand. BTW, my apology for being a tad too harsh.

Regards,
Ankur.

Ankur, thanks for your answer.

1. This is a ship rebuiling, so the systems are all new
2. Blanketing pressure of 3 barg (is this what you ask?)
3. MAWP = 6 barg, tank desing pressure is 7 barg
4. and 5. The tank is provided with safety valves to atmosphere, and vapour recycling system with heating and a gas cooling plant.
6. Crude temperature 40 degrees Celsius

The system is not finished yet and is beeing worked on. Unfortunately, I cant provide you any sketches. I must emphasise that this is a preliminary study, not a project to design.

Regards Nina

Dear Nina Hello/Good Afternoon,
Since it is clearer info now; thus I ask that probably your system (most probably) will not be pure CO2 based.
Rather this is expected to be Inert gas based i.e. most usually a CO2& N2 mixture being combustion bye product utilized for this purpose,
I believe Googling for 'inert gas blanketting' should prove helpful
Hope this helps
Best Regards
Qalander

[NSF]

NSF,

When you provide very vague details about your requirements, naturally people who read your posting are going to feel puzzled and disappointed by the inadequacy of the details.

You have not provided your system details nor have you provided a sketch for the person to interpret. Alright, let us get some more details about your CO2 blanketing system:

1. Is it an existing blanketing system or do you intend to provide a new blanketing system?

2. What blanketing pressure has been used or is intended to be used? This question is extremely relevant because the partial pressures of the system components will help in determining the solubility of CO2.

3. Is the tank MAWP & MAWV adequate to have a blanketing system?

4. How is overpressure relieved from the tank if the blanketing valve fails open or vacuum conditions avoided if the blanketing is not available?

5. Where is the crude oil tank vented - a) to atmosphere? or to a vapor recovery system?

6. What is the storage temperature in the crude oil tank? This is because the solubility is also a function of the temperature of the tank contents.

You must realize that when you have provided the above details, then only a proper response can be formulated. Engineering is based on inputs, a minimum number of correct inputs are required to provide an engineering response.

Hope you understand. BTW, my apology for being a tad too harsh.

Regards,
Ankur.

Ankur, thanks for your answer.

1. This is a ship rebuiling, so the systems are all new
2. Blanketing pressure of 3 barg (is this what you ask?)
3. MAWP = 6 barg, tank desing pressure is 7 barg
4. and 5. The tank is provided with safety valves to atmosphere, and vapour recycling system with heating and a gas cooling plant.
6. Crude temperature 40 degrees Celsius

The system is not finished yet and is beeing worked on. Unfortunately, I cant provide you any sketches. I must emphasise that this is a preliminary study, not a project to design.

Regards Nina

Dear Nina Hello/Good Afternoon,
Since it is clearer info now; thus I ask that probably your system (most probably) will not be pure CO2 based.
Rather this is expected to be Inert gas based i.e. most usually a CO2& N2 mixture being combustion bye product utilized for this purpose,
I believe Googling for 'inert gas blanketting' should prove helpful
Hope this helps
Best Regards
Qalander

Qalander,

The inert gas will be purly CO2, no mixture.

[ankur2061]

[/quote]

Ankur, thanks for your answer.

1. This is a ship rebuiling, so the systems are all new
2. Blanketing pressure of 3 barg (is this what you ask?)
3. MAWP = 6 barg, tank desing pressure is 7 barg
4. and 5. The tank is provided with safety valves to atmosphere, and vapour recycling system with heating and a gas cooling plant.
6. Crude temperature 40 degrees Celsius

The system is not finished yet and is beeing worked on. Unfortunately, I cant provide you any sketches. I must emphasise that this is a preliminary study, not a project to design.

Regards Nina
[/quote]


Nina,

Unfortunately I have more questions to ask before I reach a conclusion:

1. What is the basic premise or need for blanketing your tank? Dry inert gas Blanketing is generally provided to reduce/prevent loss of volatile products or ingress of moisture if the stored product is hygroscopic. As I understand crude oil generally has low vapor pressures and residual moisture in crude oil is taken care during the crude refining. Moreover you have mentioned that there is a vapor recycling or recovery system. Why would anyone want to load the vapor recycling gas with inert gas from blanketing?

2. Another issue is the blanketing pressure you have mentioned of 3 bar(g). I have never heard of such high blanketing pressures for storage tanks. Generally these are of the order of 0.0075 to 0.01 bar(g). How did you arrive at the value of 3 bar(g)?

As a general rule the solubility of inert gases in crude oil is very low (ppmv levels) that it can be practically ignored & not worth the exercise.

What I am more concerned about is whether your tank is designed for the intended blanketing...??

I would suggest you read the previous post in this very forum which talks about the design conditions for a tank which needs to be blanketed and also the blanketing pressures generally employed for blanketing.

http://www.cheresour...?showtopic=7305

Regards,
Ankur.

[Qalander (Chem)]

Dear Nina/ ankur hello, this has been an interesting thread indeed!

To Nina; although I accept your info on pure CO2 usage but since I've had experience with ocean-going crude carriers employing an inter-gas produced on-board vessels(ships) mainly consisting of a mixture of CO2& N2.

To ankur; As I've mentioned above that in most of the today's volatile cargo ocean-going tankers (carrying Crude Oil,Naphtha Mo gas etc.) they do have especially designed tanks to withstand pressures in the range of 5~7barg or higher (someone may correct if wrong).

As such blanketing with higher pressure mentioned by Nina is not strange.

You are right that there is vapor recovery system but the whole system is almost continuously kept under positive inerting media pressures while handling dangerous cargoes as above to ensure O2% below the desired safe minimum limits of 2% or less.

Hope this clarifies the situation somewhat.
Best Regards
Qalander