5 replies to this topic

[tanvisinha]

Suppose there is a vessel with a fixed volume of 2000 cubic metres. A fuel gas is generated at the rate of 50000 kg/h which enters the vessel and is consumed at the same rate, i.e., 50000 kg/h. A pressure of 4 kg/cm^2 is maintained in the vessel. The fuel goes to the flare if the pressure in the vessel exceeds 4.25 kg/cm^2. Now, if the generation rate of the fuel increases to 57000 kg/h, keeping the consumption rate unchanged (50000 kg/h), by how much should the fixed volume of the vessel increased so that the fuel does not go to the flare (i.e., keeping the vessel pressure below 4.25 kg/cm^2). The density of the fuel is 0.8 kg/m^3. Calculations are to be done for 1 hour.

 

Thanks in advance.

Edited by tanvisinha, 17 December 2014 - 11:40 PM.

[Aneken]

tanvisinha

 

I have read your question. I have following doubts:

 

1. Whats the use of vessel.? 2000 m3 is a very large volume. Think practically. I don't think it can be fabricated.

2. Density of the fuel? At what T,P.?

3. The molecular weight of the fuel gas.?

Edited by Aneken, 18 December 2014 - 02:33 AM.

[tanvisinha]

Aneken, thanks for your reply.

 

The density is 0.8 kg/m^3 at NTP conditions.

 

The molecular weight of the fuel is 18 g/mol and a temperature of 40 degrees Celcius is maintained in the vessel.

 

Can't a vessel of this volume be operated at a refinery? If not, say the volume is less than 2000 cubic metres. Can you guide me how to approach this problem?

Edited by tanvisinha, 18 December 2014 - 04:04 AM.

[Aneken]

tanvisinha

 

FYI,2000 cubic meters of water would be enough to cover an American football field to a depth of 15 inches. Its a huge volume.

Source:https://answers.yaho...17102117AAWQqHB

 

Before commenting anything on your query, i want to know  the function of such a large vessel.?

[tanvisinha]

Aneken,

 

Somebody asked me this question. As far as I know, the vessel is to be used for storing the fuel which is produced at different units and then it is taken out from the vessel for further use.

[Aneken]

I dont think such huge vessel is feasible. So i would like to discuss the similar situation.

 

I think i have the flexibility of reducing your query to a much simpler form.

 

Now, imagine this simple situation. Suppose we have a vessel of lets say x cu.m.

 

Now , you start filling the vessel with gas. As a result of which the pressure starts increasing (if we start filling a gas in a container of fixed volume , the pressure increases).

 

Note that the volume of the gas will be equivalent to the volume of the vessel (in your case 2000 cu. m)

 

Accc. to your query the pressure can be increased to 4 kg/cm2.

 

Now apply real gas eqn.

 

PV=ZnRT (you have to calculate Z, for you fuel gas)

 

P = 4 Kg/cm2g or 4 atm(approx)

V= 2000 cu.m

R=0.082057 m3 atm /Kmol/K

T=273+40 K

Calculate, n i.e. no. of moles

and than multiply with molecular weight of gas.

 

This will calculate the amount of gas you can store in a vessel for a fixed pressure.

Increasing the amount of gas , will increase the pressure. So you have the liberty to play with Volume parameter (either increase the radius or dia. for cylinderical shape of vessel ) to keep the pressure fix.

 

Do note that , the volume occupied by gas in a vessel is equal to the volume of vessel.

 

I hope this solves your query.

Edited by Aneken, 20 December 2014 - 01:16 AM.