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Hydrogen From Lpg!


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#1

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Posted 18 March 2008 - 10:49 AM

hello everybody!!

i am new here and i hope i can find answers to my problems because my last year project is about hydrogen production from LPG by autothermal reforming and it isvery difficult to find necessary data or flowsheet about the system. I had decided to make tha plant with desulphurization unit, autothermal reactor, steam reformer, water gas shift reactor , pressure swing adsorption and other purification units and of course some heat exchangers between reactors. basic flow sheet is almst cleared in my mind. but mass and energy balances are very very hard to get. i need to know conversion of reactions, temperatures and pressures

if you are interested in, please pleasee i am waiting your answerss...

best regardss

#2 Art Montemayor

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Posted 18 March 2008 - 11:47 AM


Merve:

I don’t know where you are at or your age, since your profile is blank, but what you state is not true. It took me less than 30 seconds to find a report on what you are looking for, in the Google Search Engine. Go to:
http://192.192.255.1...10-Tim Chen.pdf

I think you are not familiar with Hydrogen production or just exactly what the new, invented term of “autothermal reforming” represents. This is an invented term for combining two well-known and practiced industrial processes for producing hydrogen: partial oxidation and steam reforming. I am very familiar with them and have been involved in the design, fabrication, and operation of various steam reforming units. Therefore, I can speak with experience and that experience tells me before I even read the “news” and propaganda about “autothermal reforming” that a lot of the information is nothing more than “Spin” for now. If this process is ever going to get off the ground, someone is going to have to put industrial-level development costs and effort into it – not academic exercises like those being reported. The basic Chemistry and Thermodynamics are well known have been applied for many years. They are nothing new. The economic and successful combination of both processes is what is yet to be proven. And we are waiting.

The positive features of this “new” process that are being thrown about are mostly not practically true. Unfortunately, the information is being dealt with as if it is a new discovery – when in reality, the technology is older than I am (and that is very old!). But that’s OK. Electrolytic hydrogen was also being touted the same way until the public awoke to the fact that the production costs were more expensive than the product. We engineers knew that all along; it took the public about 25 years to find out the truth.

The point I want to make with you is that you have chosen a “process” that doesn’t have a proven industrial track record - yet. It may, in the future. But right now, real credible sources like Haldor-Topsoe (http://www.topsoe.com/site.nsf/all/BBNN-5PFHYF?OpenDocument) don’t report the kind of so-called advantages that the academics were predicting. For example, Haldor states “The oxygen-fired Autothermal Reformer (ATR) offers a simple straight-forward process lay-out, where plot area and construction costs are reduced due to the compact design as compared to a tubular reformer”. It never claims any operating cost advantages – as was predicted by academia. In fact, Haldor uses pure Oxygen as the oxidant feed – not air! This is a very large and costly difference when one talks about an industrial operation. I’m not saying that the Autothermal process won’t make it; I’m stating that in my experience, it has not established a credible, competitive track record. We have to give it a fair chance at competing. I would not count steam reforming out just yet. And that is the real reason you are not finding complete, industrial-based operating information about the process.

You can forget about getting any mass and energy balance for this process. That is up to you to generate if you are, indeed, charged with producing a Final Year Project Report.

You are going to find that obtaining credible “conversion of reactions, temperatures and pressures” is going to be next to impossible. You may find some lab data, or even some pilot plant experimental data. But I don’t believe the “Big Boys” like Haldor-Topsoe are going to give away their secrets after investing their hard cash on process development. I wish you a lot of luck, but I think you selected a “conceptual” and blue-sky type of project which will have to be based on mostly academic pure calculations or guesses. That’s all you can do when the process isn’t being revealed publicly. And it hasn’t gone “public” because there isn’t an established, lengthy track record – as there is for partial oxidation and steam reforming.

Good Luck.


#3

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Posted 19 March 2008 - 04:27 AM

Hi Art,
I have read a number of your contributions over the last couple of years and I have come to respect your opinion as that of someone who really knows what they are talking about with regards to process Engineering. I am also a final year student at a University in Zimbabwe and i am doing a Gas to Liquids plant with Coal Bed methane feed stock and I have intentions of using ATR in the syngas manufacture section. I understand that Sasol has used Haldor Topsoe ATR successfully in their Secunda plant since 2003/2004 and the Mossgas has als rn successfuly on the same technology, Now because I do view you as a credible person could you help me understand what you mean by it is " a process without a proven Industrial track record yet."?

#4 Art Montemayor

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Posted 20 March 2008 - 08:52 AM


Sheu:

You present a practical and important question regarding the evaluation of chemical plant processes. This is not an easy subject for a student who is controlled in what he is taught and what he has available to him/her at the university level. But nevertheless, as with almost all things engineering, life is hardly ever “fair” and the engineer – particularly the engineering student – must be resourceful when he faces a perplexing problem or a questionable situation. One way – the Direct Way – is to challenge an assertion. This is the best (in my opinion) way to clear the air and obtain more information or to discard the assertion. I commend you for posting your query. It shows you are not only interested, but you are also forcing a more specific and convincing response. That is the engineering way and I wish more engineering students were as resourceful and challenging. When you challenge you leave yourself open to either be convinced of your belief or to discard it. But to challenge effectively, you must be well prepared to accept a detailed and specific answer to analyze it and evaluate it. This takes a dedicated prior work and study on the subject – something that some engineering students are reluctant to undertake. Obviously, you feel you are prepared in your background and confident you are capable of evaluating a response. I consider that commendable.

You will note that I qualified my response to Merve with a “ – yet”. What I meant to say was what I expressed in my follow-up sentence: “It may, in the future.” To elaborate more specifically, let me bring up the example of the Steam Reforming process itself. This process was known from as early as the 1930’s. At that time, the hydrogen production process in vogue was the electrolysis of water and it took several things to occur successfully for Steam Reforming to overcome and pass the electrolytic process. First, a commercially viable, dependable, and economically competitive process was developed for the removal of CO2. Up to that time this was a huge problem because caustic scrubbers and water were the primary means of doing that. But these were only effective at very high pressures that could not be designed at that time due to metallurgy and technological barriers. Then the Amine process was patented by the Girdler Corporation in 1930 – but it had to proven at the commercial / industrial level in a manner that was convincing to every potential producer. The main factors to be proven empirically were that it was safe, viable, dependable, economic, and gave better, over-all results. This took approximately 10 to 15 years of industrial applications. Many “bugs” were found with the Amine process. Most were fixed, some are still imbedded in the process. But the solution worked. Next, the Steam Reforming process itself had to prove that it was more economical and more desirable than the electrolytic. The increasing demand for hydrogen production of less purity than the electrolytic product (electrolytic gave 99.5+% vol. and steam reforming gave 95 -98% vol.) gave the steam reforming method an incentive to be employed. More investment was justified – especially since the advantage of the steam reformer was that bulk production was much easier and this immediately reduced the unit production cost of hydrogen production. However, many problems arose with the steam reformer: special alloys were not available and had to be developed for the very high temperatures and the special catalysts required. Higher pressures had to be achieved - and the means to develop them and safely contain them as well. Control instrumentation was in its infancy and also had to be developed. All this took time, money, development, experimentation, and some losses. The market demand for hydrogen sustained the hopes and investment in the process and the answers as we know them today were found. In the meantime, the Texaco Oil Company developed a competing process, Partial Oxidation, for the production of bulk hydrogen intended for hydro-reforming at the refinery level. I think you know the rest of the story. Steam reforming has had the edge on Partial Oxidation – but not necessarily because it is “better”. Production capacity size, investment involved, licensing costs, operational know-how, business strategy plans, financing availability, and many other factors enter into whether a certain licensed or special catalyst-dependent process is really a good or better investment. And these factors all merge to determine the future “reputation”, economic success, or eventual establishment of an industrial process. It is never a matter of one, two, three, or more plants using the process and proving that it works. There are many other factors that come into play. One example of this is that from a business point of view, it is not considered very smart business to contractually tie yourself to using only one, specific catalyst or catalyst supplier. As you can well imagine, this would mean that the hydrogen manufacturer would be at the mercy of the catalyst supplier’s price increases after making a very large capital investment. Unless special government programs (guarantees, subsidies, loans, etc.) are involved, a financial institution (such as the World Bank) will not finance or back up such a risky venture.

There are a lot of things that have not been revealed about the autothermal process. This is normal for a new process method. Many interests may be involved that we still don’t have knowledge of. Catalysts and catalyst development may be just one. Patents and licenses are still others. As an example I pointed out the fact that even Haldor-Topsoe does not dedicate a webpage to the process – and they should be considered one of the top players in the process’ development. As I pointed out, while the academics are talking about using air as the oxidant vehicle, Haldor is specifying pure oxygen. If I were you, I would take a very serious look as this difference of process description. There is a BIG difference in process design and controls between both process versions. And this is just ONE detail being let out.

The biggest test is for there to be formal, accurate, and detailed operating data available over the process that will enable an accurate economic evaluation for its comparison with other accepted processes. This, as I said, is yet to be done on the industrial level. This vital information is necessary in order to facilitate the “catalyst” of any major, world-scale process being designed and built: THE FINANCIAL MONEY. The bottom line in any major project is not about the engineering; it is about making money. Please don’t ever forget that important and vital priority. The entities that finance the project must be satisfied that it is a safe, viable, and secure venture and that it will make more profit than the other options available to them. This is how the process industry is run and operated. It is not about chemistry, physics, engineering, or process simulations and calculations. It is about making money. That is the incentive that will make the autothermal process successful or not.

I hope I have not bored you or lessened your enthusiasm for your Final Year Project with this very long and specific explanation of what I mean by a proven process. I consider what I have explained to you (& hopefully other aspiring Chemical Engineering students) to be the essence of all that is professional engineering and that is why I have taken this time and effort to explain it to you. It is very, very important to know these basics truths and underpinnings of our profession and unfortunately these facts are not discussed or taught in detail at the university level – in my opinion. However, rest assured that if you succeed in becoming a professional engineer, you will be confronted with these facts sooner than later. We must make a profit for our employer. Otherwise, we don't justify our salary and we don’t have a job.





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