| Author | Islam, Md. Raisul |
| Call Number | AIT Thesis no.ET-95-17 |
| Subject(s) | Fluidized-bed combustion
|
| Note | A thesis submitted in partial fulfillment of the requirement for the degree of Master of
Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | This report represents results of gasification of sawdust, sawdust pellet and lignite in spouted beds. Two distributor designs were used in the study: a conventional circular central jet distributor and a recently proposed design in which the air inlet was in the form of a circular slit. Pellet showed the best gasification performance among these fuels. Maximum concentration of CO, H2 and CH4 in the gas for this fuel were found to be about 18, 9.5 and 4% respectively for air flow rate of 120 I/min. and air fuel ratio of 1.8. For sawdust with the same operating conditions these values were about 12.7, 2.8 and 2.16% respectively. Lignite gave better gasification performance at higher bed depth. At bed depth of 22.3 cm., concentration of CO, H2 and CH4 were 17, 10.2 and 1.15 % respectively during gasification of lignite with the same operating conditions. Central jet distributor gave better gas quality then circular slit distributor. Of course the air flow rate of circular slit distributor was higher. This study also included the experimental investigation of catalytic effect of dolomite to crack tar in the produced gas. Dolomite was used as both primary and secondary catalyst at different operating temperature. It was found to be not so effective as a primary catalyst and was affected by bed temperature. However it showed spectacular performance as secondary catalyst at high temperature; at 900°C, tar conversion of about 97 .19% and tar content in the exit gas of about only 0.049 gm/m3 of gas was achieved. Gas quality was also improved when dolomite was used as secondary catalyst. A comparative study of spouting pressure drop, pressure drop across distributor and the minimum spouting velocity was carried out with circular slit distributor of three different opening areas (176.7, 353.4 and 706.80 mm 2). A significant change in minimum spouting velocity, spouting pressure drop and pressure drop across distributor was observed with the change of their opening areas, bed particle size and bed weight. Spouting pressure drop was almost independent of distributor opening area and pressure drop across distributor decreased with the increase of its opening area. The minimum spouting velocity increased with particle size as well as bed weight. Compared to a central jet distributor, circular slit distributors had both higher minimum spouting velocity and spouting pressure drop. |
| Year | 1995 |
| 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, Sribas C.; |
| Examination Committee(s) | Surapong Chirarattananon;Kumar, Sivanappan; |
| Scholarship Donor(s) | ADB (Japan); |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1995 |