There’s a question I’m not quite sure about; I’d like to ask everyone for help!
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This post was last edited by caocheng on 2019-5-17 08:39. Why is nitrogen used to transport coal powder during the startup of Shell’s gasification process, while CO2 is used for transporting coal powder during normal operation? I don’t quite understand it; thanks to the expert!
I haven’t had direct experience with it, but using inert gases for transportation is certainly a way to prevent dust explosions. Since carbon dioxide cannot be produced in the subsequent processes while driving, nitrogen is used; once the shift reaction and decarburization are operating properly, carbon dioxide will be used. The capacity of the air separation unit and the hydrogen-to-nitrogen ratio of the gases determine this
To minimize the content of inert gases in the syngas
There is no CO2 before driving; self-production and self-sale are only possible after the gasification furnace generates CO2 while the vehicle is in operation. Both N2 and CO2 are inert gases, making them safe.
It still depends on the products to be produced later; if it is liquid ammonia, then nitrogen will be used for transportation.
Without understanding this process, conventional analysis is performed. Pulverized coal is likely to be transported by pneumatic means, which requires the use of gas. N2 and CO2 were chosen as they are safe, inexpensive, and do not introduce any unwanted gases; N2 comes from air separation units, while CO2 is probably generated as a byproduct of subsequent processes and needs to be emitted. If there is available CO2 that can be emitted, it is naturally used to reduce the need for N2. At the beginning of operation, when there isn’t enough CO2 in terms of quantity and quality, N2 has to be used instead
Inert gas is used for transporting pulverized coal. During startup, since there is no CO2 gas along with low methane levels, nitrogen has to be used temporarily; carbon dioxide is used later in the process. The reasons for this are: 1. to save nitrogen, and 2. carbon dioxide can be purified and removed after entering the gasification furnace, whereas nitrogen, acting as an inert gas, requires energy to be processed during synthesis