Oil and Water Separation: Fluid Flow and Vessel Sizing Analysis

[SherlockOhms]

Homework Statement

A fluid which is flowing at 3600 m3/hr, at a pressure of 2.3MPa and a temperature of 75°C is to be separated using a vertical separator vessel. The composition of the fluid is 50% water and 50% oil.

1. Assume perfect separation and a residence time of 20 seconds in the separator.
2. The oil has a MW of 100 and a density of 900kg/m3
3. Give estimates for line sizes and vessel dimensions
Your answer is to be a simple PFD (with stream table):
Pressure
Temperature
kmoles oil
kmoles water
Total moles
Mass flow water
Mass flow oil
Total mass flow
Mean molecular weight

Homework Equations

Conversions between mass, molar and volumetric flow rates.

The Attempt at a Solution

In the above problem, is it correct to assume that the temperature of the inlet stream will be the same as the two outlet streams seeing as there won't be any thermodynamic processes carried out on the mixture? Also, from the way I see it, it's only possible to calculate the molar flow rate of oil and water, it's not possible to calculate how many moles of oil and how many moles of water there are in total. Is this correct or is it actually possible to find these values?

 

[Chestermiller]

Homework Statement

In the above problem, is it correct to assume that the temperature of the inlet stream will be the same as the two outlet streams seeing as there won't be any thermodynamic processes carried out on the mixture?

Yes.

Also, from the way I see it, it's only possible to calculate the molar flow rate of oil and water, it's not possible to calculate how many moles of oil and how many moles of water there are in total. Is this correct or is it actually possible to find these values?

It's possible to calculate the number of moles of each within the separator. I think that is what they are asking for.

 

[SherlockOhms]

Yes.

It's possible to calculate the number of moles of each within the separator. I think that is what they are asking for.

That'll just be the molar flow rate times the residence time, yes?

 

[Chestermiller]

That'll just be the molar flow rate times the residence time, yes?

Yes.

 

[rezeew]

I would approach this problem by first confirming the assumptions made in the problem statement. It is important to note that perfect separation is not always achievable in real-world scenarios. Therefore, it may be necessary to consider factors such as emulsions, entrained gas, and other impurities that may affect the separation process.

Assuming perfect separation and a residence time of 20 seconds, we can calculate the volumetric flow rate of oil and water using the given mass flow rates and densities. From the given information, we can also calculate the total mass flow rate and mean molecular weight of the mixture.

Next, I would use the given composition of the fluid to calculate the molar flow rates of oil and water. This will give us an estimate of the number of moles of each component present in the mixture.

Using these values, we can then estimate the line sizes and vessel dimensions by considering the flow rates and residence time. It is important to note that these are only estimates and may need to be adjusted based on factors such as pressure drop, velocity, and other design considerations.

In conclusion, while the problem statement provides a good starting point for analyzing oil and water separation, it is important to consider other factors and make necessary adjustments to achieve an accurate and feasible solution.