Question: Why is nitrogen used as the heat-extraction fluidized air outside the SMTO regenerator?
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This post was last edited by liaifeng on 2018-8-5 at 17:24. Our system is an S-MTO unit, and the fluidizing medium used in the regenerator external heat exchanger is only nitrogen. I’m a bit confused – although nitrogen can indeed be used for fluidization, it is quite expensive. I think that using pressurized air or simply some unpurified air could also serve the purpose of fluidization. In other words, under a nitrogen-retaining process, using some unpurified air or pressurized air also meets the production requirements. I don’t understand why the design institute uses only nitrogen; are there similar devices that use something else? I’m just starting to learn; I don’t understand it yet. I hope you can give me some guidance. Thank you!
Nitrogen can be used, as can air; nitrogen isn’t necessary. Using wind can reduce the main airflow volume, but poor control can lead to afterburning
We only have a nitrogen process; I don’t know why
Nitrogen is primarily used; unpurified air can be employed in emergency situations. Using unpurified air can lead to afterburning, and combustion may occur in the external heat exchanger as well. Will this affect the fluidization of the catalyst in the external heat exchanger?
It might be good to use pressurized air and unpurified air for complete regeneration in catalytic cracking; perhaps the design team took into account the need for incomplete regeneration in MTO, as well as the oxygen-poor environment – just my personal opinion. . .
I agree more with the opinion from the 5th floor. The MTO reaction requires the catalyst to not be fully regenerated, in order to maintain a certain carbon content. If air fluidization is used for the external heat exchanger of the regenerator, it may have a certain impact on the carbon fixation amount. Our company uses second-generation technology, with two regenerators arranged coaxially; the second regenerator is used for the regeneration of the catalyst in the C4 reactor. Since the C4 catalyst is fully regenerated, the fluidization ring of the external heat exchanger in the second regenerator utilizes the main air duct (from the main fan). Similar designs include the transport of raw MTO catalysts and the transport of raw C4 cracking catalysts. Also, due to MTO’s control over carbon content, nitrogen is used for transporting the raw material; of course, there is a backup PA pipeline as well, but it has blind flanges ； The transport of the raw C4 cracking catalyst uses main air, which comes from the main air pipeline of the main fan. The external heat exchangers are all in a fluidized dense phase within the regenerator (with complete backmixing), and the MTO catalysts do not burn completely; if main airflow is used for fluidization, combustion will occur inside the external heat exchangers ； The impact on tail combustion in the dilute-phase region should be minimal (I have no practical experience).
This post was last edited by jingqingfeng on 2015-9-4 22:02. The people who commented above are all correct; I’d like to add that in addition to fluidization, there is also the high pressure required for fluidization again after the material has settled. If the wind pressure is too low, it’s best to be able to switch between using air and nitrogen.
MTO catalyst regeneration is a form of incomplete regeneration; it takes place under oxygen-deficient conditions. Using nitrogen is better than using plant air for this process, as it prevents issues such as tail burning and secondary combustion in the regenerator that can result from adjusting external heat removal. What is the format for external withdrawals?
Hello, are you a staff member at the SMTO site? If possible, I’d like to communicate and ask a few questions. Thank you!
Are you from Pucheng? Why has your DMTO stopped again?
One with three sections – only nitrogen can be used in the upper section, while the lower section allows switching between air and nitrogen