4 replies to this topic

[firefox23]

 IMG_1114.JPG   134.62KB   0 downloadsHi, I am struggling with a homogeneous reactors question and would much appreciate any help! the question I have attached as a image and all of the other information I have been give for the question i have also attached. I have the values for Xmax from a previous question and i have values for K1 at different temperatures. The reactor can be modelled as PFR and so i performed a mole balance over a small element dV to get the volume of the PFR as can be seen in the image. I also calculated molar ratios of all reactants and products and multiplied by P to get partial pressures. I then subbed these in to get the integration as shown. I am using excel and so used trapezium rule to solve the integration however the graphs i get for temperature vs. volume does not seem right and the values for volume seem much too low. Any ideas what i might have done wrong? I've also attached the graph i got for volume against temperature.  IMG_1102.JPG   91.09KB   1 downloads  IMG_1103.JPG   114.2KB   0 downloads  IMG_1104.JPG   198.83KB   0 downloads

Edited by firefox23, 30 January 2017 - 01:13 PM.

[Mahdi1980]

Hi,

 

I have checked just your integration formula,

 

If your equations are true, you can check that there is a mistake in simplifying of the last statement of the integration.

the math statement within the integral to be :

 

                                                                         dx. (1+X).2K1/ ((1-X)2k1p - p^2.X^2)

 

but you have written an additional (1+X) in the denominator. It seems that by revising your formula, the volume will be higher.

 

Please check it and solve the revised formula and let me know the result.

 

Mahdi,

[firefox23]

Hi,

 

I have checked just your integration formula,

 

If your equations are true, you can check that there is a mistake in simplifying of the last statement of the integration.

the math statement within the integral to be :

 

                                                                         dx. (1+X).2K1/ ((1-X)2k1p - p^2.X^2)

 

but you have written an additional (1+X) in the denominator. It seems that by revising your formula, the volume will be higher.

 

Please check it and solve the revised formula and let me know the result.

 

Mahdi,

Hi, there is an extra (1+x) because of the (1-x)/(1+x) term. in order to have (1+x)^2 on the numerator I have to multiply this term by (1+x) so that I have (1-x)(1+x) on the denominator. Apologies I've just realised that the (1 +x)^2k1 looks like 2 x k1

Edited by firefox23, 30 January 2017 - 12:04 PM.

[Francisco Angel]

 

Hi,

 

I have checked just your integration formula,

 

If your equations are true, you can check that there is a mistake in simplifying of the last statement of the integration.

the math statement within the integral to be :

 

                                                                         dx. (1+X).2K1/ ((1-X)2k1p - p^2.X^2)

 

but you have written an additional (1+X) in the denominator. It seems that by revising your formula, the volume will be higher.

 

Please check it and solve the revised formula and let me know the result.

 

Mahdi,

Hi, there is an extra (1+x) because of the (1-x)/(1+x) term. in order to have (1+x)^2 on the numerator I have to multiply this term by (1+x) so that I have (1-x)(1+x) on the denominator. Apologies I've just realised that the (1 +x)^2k1 looks like 2 x k1

 

 

I agree with firefox23 regarding the integration term. As for your results, you could make and order of magnitude estimate considering a CSTR like this:

 

V_CSTR=F_EB_inlet * X / r

 

You could provide more details to help others check your work, like the details to calculate K.

Best regards.

[firefox23]

 

 

Hi,

 

I have checked just your integration formula,

 

If your equations are true, you can check that there is a mistake in simplifying of the last statement of the integration.

the math statement within the integral to be :

 

                                                                         dx. (1+X).2K1/ ((1-X)2k1p - p^2.X^2)

 

but you have written an additional (1+X) in the denominator. It seems that by revising your formula, the volume will be higher.

 

Please check it and solve the revised formula and let me know the result.

 

Mahdi,

Hi, there is an extra (1+x) because of the (1-x)/(1+x) term. in order to have (1+x)^2 on the numerator I have to multiply this term by (1+x) so that I have (1-x)(1+x) on the denominator. Apologies I've just realised that the (1 +x)^2k1 looks like 2 x k1

 

 

I agree with firefox23 regarding the integration term. As for your results, you could make and order of magnitude estimate considering a CSTR like this:

 

V_CSTR=F_EB_inlet * X / r

 

You could provide more details to help others check your work, like the details to calculate K.

Best regards.

 

Thanks, i'll try it with your suggestions. Details for k are now also attached to the main post