8 replies to this topic

[tumza]

produce 41100 metric tons per year of hydrogen gas at 97.4mol% purity at 20 bar absolute pressure and 43 C, by steam reforming the naphtha?

 

feed of naphtha at 30 C and 25 bar absolute pressure.

Component

Mol%

Hydrogen

52.01

Carbon

0.84

Sulphur

22ppm by weight

the naphtha contains 15.3% hydrogen by mass. The average molecular formula of this naphtha is C₁₁H₂₄.

 

Questions

1.Desulfiration on naptha to H2S material balance?

2.conversion of naptha in primary and secondary reformer?

3.How much Steam to carbon ratio should i use since the process requires alot of energy?

 

Best Regards

 

 

 

[PingPong]

Is this a project for your study? Or what?

[tumza]

Hi

 

Its part of my college project.

[PingPong]

I thought so, because a naphtha with on average 11 C atoms, which would actually be a mixture of molecules with 9 to 13 C atoms, is a very heavy naphtha. That is really a light kero. I doubt that anybody runs a steam reformer with such heavy feed, or that a licensor would be willing to design for such heavy feed.

 

And what does

 

Hydrogen 52.01

 

and

 

Carbon 0.84

 

mean ?

[tumza]

Hi PingPong

 

that is the nominal composition of hydrogen and carbon in the naptha, Hydrogen 52%(mol%) and carbon 0.84%(mol%) and sulphur 22ppm by weight,am currently busy with the material balance for the project,

• firstly i converted the 41100 metric tons/year of hydrogen produced to kmol/hr by dividing by molar mass of hydrogen and converting tons to kilogram=23000000  kmol/hr of hydrogen produced.

1.my other question now, is since in the primary reformer all the naptha reacting with steam is converted to methane,CO,CO2 and some hydrogen gas does the the reaction below holds:

 

C₁₁H₂₄+H₂O>>CO₂+CO+CH₄+H₂

 

   _{1:11>>>1:9:1:21}

 

2.will the total carbon in the naptha entering the primary reformer be (11*0.084%).

 

3.in terms of conversion per primary or secondary reformer do i have to go the equilibruim(find Kc & K p) route to determine the conversion i can make assumption for the conversion and worked it out?

 

4.Steam to carbon ratio in the primary reformer inlet,how much should i use to sastisfy enough steam supply in the secondary reformer?

[PingPong]

that is the nominal composition of hydrogen and carbon in the naptha, Hydrogen 52%(mol%) and carbon 0.84%(mol%)

That is nonsens.

 

firstly i converted the 41100 metric tons/year of hydrogen produced to kmol/hr by dividing by molar mass of hydrogen

Note that the hydrogen product is only 97.4 mol% so its MW is much higher than that of pure hydrogen.

 

1. First of all: what you call primary reformer is normally called Prereformer.

The primary reformer is the reformer heater (which you seem to call secondary reformer)

A secondary reformer could be an autothermal reformer (using air or pure oxygen) located downstream the reformer heater.

 

In the prereformer all C₁₁H₂₄ will indeed be converted into CO₂ plus CO plus CH₄ plus H₂ but amounts of each depend on equilibrium Kp's (and approach to equilibrium ATE for methanation and watergas shift reactions) at prereformer outlet T and P.

 

2. Carbon in the naphtha will obviously be the C₁₁ part of the C₁₁H₂₄

 

3. Use K_p's and ATE's for both the methanation and watergas shift equilibria at heater outlet P and T (like for prereformer)

 

4. Normally steam is added at prereformer feed and more steam downstream prereformer before reformer heater. Different licensors will use different S/C ratios, but I suggest that for (very) heavy naphtha you use S/C ratios of at least 2.5 for prereformer inlet, as well as for reformer heater inlet.

 

Your questions make me wonder: are you a chemical engineer or a mechanical engineer?

Edited by PingPong, 02 October 2014 - 09:07 AM.

[Art Montemayor]

Tumza:

 

Your communications skills need a vast improvement.  Since you are still in college, you should take advantage of some courses on writing and communicating correctly and effectively.  PingPong, in his usual fashion is trying to help you out with specific details but is handicapped because of a lack of correct and accurate data - including the real, entire story of this topic.

 

This thread belongs in the Student Forum and I am transferring it there.  In the meantime, if you desire explicit, detailed help from our members, please help them out by furnishing ALL your information and basic data up front.  They can only help you out as much as you help them with the basic data.

[tumza]

Hi PingPong

 

Thanks for the valuable feedback and input,am doing my second semester in college,please find below an extraction from the project itself,

 

Design a plant to produce 41100 metric tons per year of hydrogen gas at 97.4mol% purity at 20 bar absolute pressure and 43 C, by steam reforming the naphtha. The composition of carbon monoxide and carbon dioxide in the product should each be less than 10ppm. The plant has a feed of naphtha at 30 C and 25 bar absolute pressure.The company supplying the naphtha reports that the nominal composition of hydrogen and carbon is:

 

Component-Mol%

Hydrogen-52.01

Carbon-0.84

Sulphur-22ppm by weight

• Empirical study suggests the naphtha contains 15.3% hydrogen by mass. The average molecular formula of this naphtha is C₁₁H₂₄.

Edited by tumza, 04 October 2014 - 12:08 AM.

[tumza]

Hi Art Montemayor

 

my apologies for the poor communication,i have started attending communication skills workshops to improve and enhance my communication skills.

 

Thanks for the valuable feedback.