Reward-based search: Design requirements for changing the carrier gas in dense-phase transport from N2 to CO2
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In dry coal powder fluidized bed gasification, N2 is generally used as the carrier gas; as a result, the synthetic gas produced will inevitably contain a high level of N2. If this synthetic gas is used in Fischer-Tropsch synthesis or other synthetic processes, the high concentration of N2 will cause the subsequent synthesis units to emit large amounts of gas, increase the load on the compressors, and reduce the effective volume of the synthesis reactors. Therefore, for dry coal powder gasification used to produce syngas, changing the carrier gas from N2 to CO2 is one approach. Among SHELL’s gasification users in China, companies such as Zhongyuan Dahuahua and Henan Kaixiang seem to have carried out such modifications. So, those who are aware of this could please explain what aspects need attention during the modification process? Such as the material selection for pipes, valves, and instruments ； Changes to the control scheme. Here it is for everyone’s reference.
This post was last edited by GSP on 2009-12-23 at 16:01. There is generally a sort of unwritten rule in the industry; haha, it is that CO2 is used for producing methanol at the downstream stage, while N2 is used for producing synthetic ammonia. In my opinion, there shouldn’t be much difference in terms of transportation efficiency between the two, though there may be some differences when separating the gases at the outlet for delivery to the downstream processes. As a carrier gas for transportation, it is sufficient that its purity and pressure meet the required standards. I have worked on dry powder research projects, and the theoretical differences are not significant.
For version G, after switching the carrier gas to CO2, the material of the pipes was changed. Are there any specific requirements regarding the CO2 concentration and the operating parameters?
After all, SHELL gasification is used less often for synthesizing ammonia and producing hydrogen; in the future, it will most likely still be used for synthesis purposes. So I encourage everyone to engage in lively discussions on this topic! !
First and foremost, the purity of CO2 must be taken into consideration; this is especially true for CO2 obtained through low-temperature methanol washing, as some manufacturers have encountered problems where the filling nozzles became clogged by sulfur present in the CO2 after modifications were made.
The CO2 concentration obtained through low-temperature methanol washing generally reaches around 87%; to achieve a higher concentration, additional measures are required. Moreover, the total sulfur content in this gas cannot be very high, and it consists of COS and H2S. So what causes all of the sulfur to precipitate? Furthermore, according to literature, in CO2, in addition to the total sulfur content, levels of H2O, CH3OH, etc., are also required. If the following composition is met: CO2 98.97 %v ； N2 0.005 %v ； CH4 0.010 %v ； Ar 0.000 %v ； H2 0.220 %v ； CO 0.770 %v ； MeOH 0.030 %v ； H2S