| Author | Dutta, Animesh |
| Call Number | AIT Thesis no. ET-98-14 |
| Subject(s) | Biomass energy
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The present study was undertaken for getting low tar gas by improving the multistage/hybrid gasification processes. Experimental investigation of hybrid updraft-downdraft
gasification and hybrid wood-charcoal gasification was conducted. Two-stage briquette
gasification and two-stage wood gasification with preheater was also carried out in this regard.
The performance measures included the tar content, gas composition and net heating value of
the producer gas.
The results of the investigation revealed the followings. Although tar content of the
product gas in briquette gasification was found higher than wood gasification; the difference in
tar content diminished significantly at higher flow rates and a higher net heating value of gas
was obtained. But pressure drop gradient (~p/cm) across the reactor bed for briquette
gasification was found 4 to 6 times than that of wood gasification. In hybrid updraftdowndraft gasification, for six of the nine experimental runs, a tar free gas was obtained in the
down draft end. A very high concentration of CO and a very low concentration of H2 and C02
was found in the product gas. It also seems to be potential for cogeneration. Hybrid woodcharcoal gasifier was also shown promising in respect to get higher net heating value of gas
and the lowest tar content was found only 9.83 mg/Nm3 in this unit. Two-stage wood gasifier
with preheater shows an exemplary idea for using in an Internal Combustion Engine as nearly
tar free gas was obtained by supplying preheated air to the gasifier and the exhaust gas from
the engines has the potential to heat the inlet air of the gasifier. For five of the experimental
runs, tar content of the gas was found below 10 mg/Nm3 which can be possible to used in
engine without scrubbing by heating the supply air in the range of 250-185 °C.
For all of these cases except two-stage briquette gasification, an exceptionally high
temperature was obtained in the combustion/reduction zone that helped to crack the tar. It was
also found that for a particular primary air flow rate, increase in the secondary and tertiary air
flow between the operation limit resulted in decrease in tar content as well as C02 and H2
concentration while that of CO increases. |
| Year | 1998 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Bhattacharya, S. C. ; |
| Examination Committee(s) | Surapong C. ;Kumar, S. ;Pham, H. L.; |
| Scholarship Donor(s) | The Royal Netherlands Government. ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |