Dear researchers,
Has anyone here found low content of carbon monoxide (CO) in syngas from biomass gasification? I mean percentages below 5,0%. Even if the answer is no, there would be an explanation for that? Most of the literature that I have analyzed shows content in the range of 10 to 20%. The lowest, and only one, that I have found was 6.9%. I really appreciate your comments. Thanks.
Hi, I guess it is because water gas shift reaction (WGS), you can google it first. If there is a high content of moisture in your gasification atmosphere, or merely the CO2 in your system is removed someway, then the equilibrium of WGS can be shifted largely towards product, rendering a low content of CO in your syngas. Hope it helps.
Dear Yinqiang,
Thank you for taking some of your time to comment on my post. At first, I thought that could be the reason for the low CO content, and also made some comments in my writing up about the WGS. What made me go through this topic is that the moisture content of the fuel is below 10%. But now that you mentioned this, perhaps the moisture present in the air might be affecting the reaction. This is quite interesting since there is no research discussing this topic specifically. Once again, thank you.
Dear Humberto Santos,
You have asked really Interesting question. Initially i want to know, why do you want low CO syn-gas? Normally biomass syngas used for direct power generation (by burning) where CO is act like fuel. Some cases where Hydrogen percentage required to be increased, there water gas shift reactor used for the conversion of CO to CO2 and splinting of H2O to form H2. (You can see in Wiki).
Now, I will answer your question. Normally in Biomass syngas conversion system temperature of biomass rise in steps. So, initially all moisture is removed from biomass. Before gasification there is 30-40% carbon, 30 to 40% oxygen and 5 to 7% hydrogen present in biomass ( typically varies in case to case). Gasification is always performed in controlled air flow, so that complete burning would be avoided. In this controlled air atmosphere there is always possibility of producing higher percentage of CO. So, Normally higher percentage of CO is present in syngas. If you want to reduce CO, you have to give more air/oxygen to gasification reaction and more oxygen means higher loss of energy from biomass ( reduced biomass to syngas conversion efficiency)
In some application CO is reduced to increase Hydrogen (Exception).
Hope you agree with me
Regards
Sagar
Dear Sagar,
Thanks for taking your time to answer my question.
Actually, it is not my intention to reduce CO in the gas mixture. My objective is to find an acceptable explanation to this fact. Could a high amount of air have acted to lower CO? Or it is more probable that moisture content has acted to accelerate WGS reaction to lower CO. To be more clear, for instance, let's consider a fuel gas that has combustible gases in the following composition: H2 - 19.40; CH4 - 3,93; CO - 0.70. All on a molar basis.
Here is what I think. The reason for this to happen is not much air as a gasifying agent, otherwise, that amount of H2 would not have been obtained as well. So, the explanation left would be the WGS reaction accelerated during the process. It is important to mention that the biomass is from contaminated land, so some metals content in biomass could have acted as biocatalysts. Does it make sense to you, Sagar?
Regards,
What is the composition of Your gas, all components. It is easier to give an answer if we know the composition and not just one component.
What are the gasification conditions, type of gasifier used etc.
As we all know that synthesis gas or simply syngas is defined as a gas that contains chiefly hydrogen gas and co as main combustible components.Although the raw form may contain carbon dioxide and water. However, when these syn gas ( hydrogen and co) are produced from biomass i.e organic matter from plants and animals either through fluidised bed gasification or entrained flow gasification, a bio-syn gas is produced.Hence, you can adjust the composition of co and hydrogen gas from the syngas production technologies by sorption enhanced reforming, down stream shift reaction, membrane separation, pressure swing adsorption e.t.c.
The below mentioned review discusses biomass pyrolysis. Happy new year.
https://www.researchgate.net/publication/325803601_Biomass_pyrolysis_past_present_and_future?_sg=uctHsEFk-uWqt2BGZz1K59-bi1t7VgNQEeXRDjXwvs2gsxu-Evn22Yb7YPx7DmkKLyzfP2k-9rjw3FbvbhEXHrYpY1-5eCp6PAMROxnl.NHWOapbTShJUMlZncKuCGor7UggmB3jS6JxupfrVf8zXykLkVKft9kzOsJwTPOdVbciIKza7L0ekkM8gUc4gaw
It all depends on the feedstock, composition, processing conditions and whether any catalysts were used to change the gas composition. If a full feedstock analysis and gas composition were provided with process conditions, then equilibrium calculations could be used to assess possible reagents and possible changes to the conditions. Syngas is the term for gas from a pyrolysis process for biomass and producer gas for that from typically an air-blown gasifier.
How is the concentration of CO calculated? Is it mass%, mol% or volume%? And how was it measured?
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