3 replies to this topic

[F.Hakim]

I am a third year chemical engineering student from local university in my country and I would like to acquire as much information from admin or others people that could help to comment my hysys and process flow. First of all, I am one of the untalented student from my faculty, moreover I am not well known about the real life situation of chemical engineering process.

Thus, to put it simply. Here is my question:-

1. Could you guys (admin or who have experience or knowledge) comment on my Hysys.

2. Could my hysys design being implemented in real life.

3. It is possible to have heat exchanger in series.

4. If I want to cool down the stream into below -60^oC. It is possible in industry and what type of refrigerant should I choose.

5. Can the superheated stream flow in the pipe line?

 

That all for now. I hope you guys can help me to solve my problem.

Here I attach my hysys pfd, the stream information and the explanation of hysys and process background.(because i dont know how to upload a hysys here).

If you guys need more information in order to help me. Just let me know.

Lastly, if there is I do wrong please let me know because I am newcomer here.

(I already post this topic in student forum and then i found out i am working with simulation which being discuss here, i am sorry for this).

 

 Hysys PFD.pdf   24.16KB   29 downloads  hysys workbook.pdf   45.76KB   22 downloads  Process background and hysys explaination.docx   22.61KB   25 downloads

[thorium90]

There are quite a large number of minor grammatical concerns that make your description ambiguous and awkward. Eg: "The temperature is dependent to the pressure..."

 

Formal english should be used for report writing. For example, the following english is not acceptable: "For this simulation the temperature shooting high after we compressed the gas... "

 

There is also no need to use words like "we.." Formal writing should be done in the third person, not in the first person.

 

Concern for valve opening is only valid for dynamic simulations. Its not necessary to say your vlv-100 is at 50% to reduce pressure. Just mention that it is let down to the required pressure.

 

Compressor K-100 compresses the gas to 23.5bar and the final gas temperature is 462.9C. The compression ratio and temperature is not feasible. Multiple stages with intercooling will be required. Also, it is not an air compressor. This part will cause your process flow to change significantly, therefore you would need to rethink how it will flow.

 

Stream 18 was labelled as 1-propanal.

 

Your workbook says stream 17 and 20 uses PRSV.

 

Your column requires cryogenic distillation. It is not explained how you intend to do it. What will your condenser and reboiler use? Also, although stream 17 is at -65C and can be used for cooling another stream, it is not a cooling water stream. Don't create your own misnomers.

 

Further refining to the process flow can be done by including your recycle streams. You do not need to connect them now as your basic flow is not yet ready but you can state the streams to recycle rather than incinerate. Hydrogen is not free.

 

Is it even necessary to store product at >100C?

 

The following sentence is nonsensical, I suggest you rephrase it. "the purity is 100% because the other components exist in small values"

 

Is it necessary for your reaction to run that high? It seems a waste for the reaction to occur at significantly higher pressures than your separation columns. Will there be any disadvantage to run at a lower reactor pressure or advantage to run at higher column pressures? You could generate case studies to support the pressures you have chosen.

Edited by thorium90, 20 June 2013 - 02:44 AM.

[F.Hakim]

My greatest thanks goes to Mr. thorium90, i am truly honoured that you spend your time for correcting my mistake.

 

I will jog down the mistake that I have made. But, there are certain parts which I could not understand well. Additionally, I am truly sorry for grammatical error. It’s always there because English is not my native language. In spite of that I am trying hard to correcting it. Moreover, I am not fully exposed to the real industry and we learn only by books. Thus, for certain questions I could not answer your questions as I am not familiar to the industry. Thanks for your consideration.

 

Here is where I do not understand.

1. “Multiple stages with intercooling will be required. Also, it is not an air compressor”

       - By this it means that the compressor that I used in my simulation is not for the gas flow? If yes, what should I do?  Or I am misunderstood your explanation there.

2. “Also, although stream 17 is at -65C and can be used for cooling another stream, it is not a cooling water stream.”

       - Does it mean that in real industry we can’t apply this concept? The major stream line cannot replace the utilities to be used in heat exchanger?

3. “What will your condenser and reboiler use?”

       - What do you means by this sentence? I could not understand whether it is in term of refrigerant or something.

 

To answer your questions:-

1.  “Is it even necessary to store product at >100C?”

       - As I am not familiar to the industry so my answer is based on my own justification at this time. I will research it later. So I think it could not be done.

2. “Is it necessary for your reaction to run that high?”

       - I am following the operating pressure and temperature from the journal I refer to. So in my opinion, the optimum parameter is in the range stated in the journal.

 

My questions:-

1. Is there any comment on the stream 19 as the temperature too high which is 400^oC?

       - Does it possible?

 

I hope others can throw their opinion too.

Thanks.

[thorium90]

Hi,

 

A gas compressor compresses gases. An air compressor compresses air. Don't call it an air compressor if it doesn't compress air.

 

Cooling water implies water, H2O, that is used for cooling purposes. A stream that is used to cool another stream is simply known as a cold stream. Don't call it a cooling water stream if it is not water for cooling.

 

Condensers and reboilers require another stream to remove or provide the heat. This can be cooling water or steam etc. Cooling water evidently cannot be used to cool to sub zero temperatures. Some other cooling medium has to be used. Note that cryogenic distillation is a significant investment as cold generation requires higher quality materials and more equipment, of which your current flowsheet currently lacks these equipment and you would need to formulate your flow diagram to include all the necessary equipment like expanders, exchangers etc.

 

Products are typically stored at room temperature unless there is a special need for it to be kept warm. For example, if the product has a high viscosity at room temperature and it is necessary to pump the fluid later, it would be stored above ambient temperature to facilitate pumping.

 

Journal authors may sometimes use an arbitrary pressure to investigate the kinetics. This may or may not be what will be used in the actual plant. The actual pressures to use is typically a question of economics unless the reaction only occurs at specific pressures. Although it is likely the pressure used is of an optimum pressure. Still, this does not preclude the use of other pressures, and you should investigate the effects at different pressures and reaction temperatures.

 

You will need to rearrange your exchanger configurations as a compressor discharge of 463C would have melted your compressor parts. Interstage cooling would reduce your compressor discharge temperature and therefore your last query on stream 19 is moot.

 

 

Also, might I suggest reading "Chemical Process Design And Integration" by Robin Smith. It would help you in understanding process synthesis, especially the first chapter which describes onion diagrams.

Edited by thorium90, 21 June 2013 - 04:26 AM.