Significance Statement
How to remove biomass tar has been a challenge facing commercializing biomass gasification technology. Biomass tar has varying number of hydrocarbon from single ring hydrocarbon to five ring aromatic compound. Tar has not only affect biomass gasification technology but also causing clogging of fuel lines and engines. For all internal combustion engines ICE to have a stable operation, the tar concentration must be below 100mg/Nm3.
Dr. Shunsuke Nakamura and Professor Kunio Yoshikawa from Department of Environmental Science and Technology at Tokyo Institute of Technology and Dr. Shigeru Kitano from Maywa Co Ltd in Japan observed that eliminating tar concentration will give high overall energy efficiency.
Various means have been used to tackle tar concentration. The methods are generally classified into primary and secondary. The primary tar removal technologies include catalytic cracking, thermal cracking and plasma gasification with plasma gasification having a higher tar removal rate. While the secondary types include scrubber, filter, and centrifuge.This paper explains the use of scrubber for the removal of tar, since tar does not have a hydroxyl which make it difficult to separate from water. An oil absorbent was considered as alternative to water. The research team used bio-oil scrubber and char bed with the aim of removing water and heavy tar from the syngas (producer gas).
This paper explains the use of scrubber for the removal of tar, since tar does not have a hydroxyl which make it difficult to separate from water. An oil absorbent was considered as alternative to water. The research team used bio-oil scrubber and char bed with the aim of removing water and heavy tar from the syngas (producer gas).
In carrying out this experiment, Shunsuke et al. (2016) make use of two coolers, two centrifuges, two bio-oil scrubber and two char bed filters. A crushed cedar feedstock with small size was supplied into a reactor, the volatility of the feedstock produces a syngas. The produced gas contains tar and soot. And when passed through the bio-oil scrubber which has electric heater as it temperature controller. the tar compound of the syngas dissolved.
According to Shunsuke et al. (2016) tar removal performance of the bio-oil scrubber increases with the bio-oil temperature and the viscosity decreases with the increase in the absorbent temperature, causing an increase in contact area between the gas and the absorbent. Which is one of the factor affecting the scrubber’s performance. It was also discovered that the performance of oily scrubbers decreases with time as tar and ash accumulate in the scrubber and in turn affect the contact between the absorbent and the tar in the gas.
The article emphasized on the measuring of the tar removal performance in a repeated interval to know the efficiency of the oil scrubber. The difference in the tar removel performance at the same time was due to the unstable conditions in the gasifier. To maintain tar removal performance, the char in the filter is often replaced. Shunsuke et al. (2016) was able to remove 81.5% of tar from the producer gas when 13kg of char bed filter was used.
In view of eliminating biomass tar, Shunsuke et al. (2016) came up with a tar removel technology using bio-oil and char so as to make biomass gasification technology to be commercialized. This has yielded a positive result, looking at the recent article of shunsuke et al. (2016) their bio-oil scrubber and char bed filter were able to achieve 98% tar removal rate and maintain a low cost effective tar removal method. The article also established the essence of filter in the operation and there is no need of applying the primary methods.
Journal Reference
Shunsuke Nakamura1, Shigeru Kitano2, Kunio Yoshikawa1. Biomass gasification process with the tar removal technologies utilizing bio-oil scrubber and char bed. Applied Energy, Volume 170, 2016, Pages 186–192.
[expand title=”Show Affiliations”]- Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8502, Japan
- Maywa Co., Ltd, Kanazawa, Ishikawa 920-0211, Japan
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