2019 AIChE Annual Meeting
(613a) Pyrolysis and Steam Gasification Characteristics of Mangroves Under Rapid Heating Conditions
Authors
Sakurai, Y. - Presenter, Kogakuin University
Sakai, Y., Kogakuin University
Kobayashi, J., Kogakuin University
Mangroves are one of the important resources from the viewpoint of biodiversity. On the other hand, economic development in tropical countries is causing a decline in mangroves. It is thought that positive utilization of mangroves as well as its conservation are necessary in order to pursue both sustainable development and environmental preservation. The objective of this study is to clarify the characteristics of pyrolysis and steam gasification when using mangroves. The behaviors of pyrolysis and steam gasification of them are investigated and the effect of tree species and gasification conditions, such as temperature and atmosphere, on thermal decomposition characteristics are discussed. In this connection, the role of minerals in woody biomass was discussed, because it is presumed that minerals in woody biomass such as alkali and alkaline earth metals act as catalysts for steam gasification of woody biomass.
Three kinds of mangroves (Rhizophora mucronata, Bnguiera cylindrical and Avicennia marina) and Japanese cedar, Japanese cypress, eucalyptus were used as raw materials. The biomass sample was milled and sieved into 0.5~1.0 mm. After that, 1.0±0.0009 g of the sample was weighed out and dried at 110 â for 24 h. When experiments of the gasification are performed using demineralized sample, these were prepared by acid treatment described as follows. The biomass sample was soaked in HCl (0.58 mol/L) and stirred at room temperature for 1h. Thereafter, these were filtered, thoroughly washed and dried at 110 â for 24 h. Pyrolysis and gasification were carried out in the batch type tubular reactor. The inside of the reactor was under inert atmosphere with argon gas (1 L/min). The heating temperature was 800 â. The biomass sample filled in ceramic board is supplied to the heating part in reactor tube by a manual slide method, after that the thermal decomposition reaction occurs immediately. Steam gasification was carried out by adding water (0.2 mL/min) into the reactor with a syringe pump.
The current main results indicate that mangroves have high reactivity under steam gasification conditions in comparison with the other woody biomass. The produced gas yields of the mangroves under inert atmosphere were 49.9~54.0 wt%, while the gas yields of the other woody biomass were 53.3~61.7 wt%. At the same time, the gas yields of the mangroves under steam atmosphere were 68.2~81.5 wt%, while the gas yields of the other woody biomass were 65.8~73.7 wt%. From these results, the gas yields by steam gasification using the mangroves were 1.3~1.6 times greater than those under inert atmosphere, while those using the other woody biomass were 1.2~1.3 times. The concentration of both H2 and CO2 also increased with increase in conversion ratio under steam gasification conditions. This result leads us to presume that the steam reforming and water gas shift reaction are occurring remarkably in the mangroves. The catalytic function due to minerals in biomass ash is one of the reasons why the reaction between biomass and water vapor is promoted during the gasification process. Therefore, the catalytic function of the minerals was investigated, based on the gasification behavior using demineralized biomass sample as raw materials. The gas yields by steam gasification using the demineralized mangroves were almost similar to those under inert atmosphere and those were 0.96~1.06 times. The results using the other demineralized woody biomass indicated almost the same tendency. From these results, it was found that the demineralized biomass sample has poor reactivity under steam gasification conditions. It is supposed that the minerals in biomass play the role of catalysts to promote steam gasification reaction. From the above results, it was shown that the mangroves can be applied to the gasification process as well as the other woody biomass.
Three kinds of mangroves (Rhizophora mucronata, Bnguiera cylindrical and Avicennia marina) and Japanese cedar, Japanese cypress, eucalyptus were used as raw materials. The biomass sample was milled and sieved into 0.5~1.0 mm. After that, 1.0±0.0009 g of the sample was weighed out and dried at 110 â for 24 h. When experiments of the gasification are performed using demineralized sample, these were prepared by acid treatment described as follows. The biomass sample was soaked in HCl (0.58 mol/L) and stirred at room temperature for 1h. Thereafter, these were filtered, thoroughly washed and dried at 110 â for 24 h. Pyrolysis and gasification were carried out in the batch type tubular reactor. The inside of the reactor was under inert atmosphere with argon gas (1 L/min). The heating temperature was 800 â. The biomass sample filled in ceramic board is supplied to the heating part in reactor tube by a manual slide method, after that the thermal decomposition reaction occurs immediately. Steam gasification was carried out by adding water (0.2 mL/min) into the reactor with a syringe pump.
The current main results indicate that mangroves have high reactivity under steam gasification conditions in comparison with the other woody biomass. The produced gas yields of the mangroves under inert atmosphere were 49.9~54.0 wt%, while the gas yields of the other woody biomass were 53.3~61.7 wt%. At the same time, the gas yields of the mangroves under steam atmosphere were 68.2~81.5 wt%, while the gas yields of the other woody biomass were 65.8~73.7 wt%. From these results, the gas yields by steam gasification using the mangroves were 1.3~1.6 times greater than those under inert atmosphere, while those using the other woody biomass were 1.2~1.3 times. The concentration of both H2 and CO2 also increased with increase in conversion ratio under steam gasification conditions. This result leads us to presume that the steam reforming and water gas shift reaction are occurring remarkably in the mangroves. The catalytic function due to minerals in biomass ash is one of the reasons why the reaction between biomass and water vapor is promoted during the gasification process. Therefore, the catalytic function of the minerals was investigated, based on the gasification behavior using demineralized biomass sample as raw materials. The gas yields by steam gasification using the demineralized mangroves were almost similar to those under inert atmosphere and those were 0.96~1.06 times. The results using the other demineralized woody biomass indicated almost the same tendency. From these results, it was found that the demineralized biomass sample has poor reactivity under steam gasification conditions. It is supposed that the minerals in biomass play the role of catalysts to promote steam gasification reaction. From the above results, it was shown that the mangroves can be applied to the gasification process as well as the other woody biomass.