Production and combustion behavior of rice straw pellets | |
| Author | Dao Ngoc Cuong |
| Call Number | AIT Thesis no.ET-16-13 |
| Subject(s) | Biomass energy Straw as fuel |
| Note | A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Engineering in Energy |
| Publisher | Asian Institute of Technology |
| Abstract | Rice straw is one of the most important agricultural residues and has a great potential in Asia especially South East Asia. Facing the problems related to fossil fuels and the depletion of woody biomass, agro – biomass like rice straw can become one feasible alternative biofuel. However, with a low energy density, handling and transporting rice straw in forms of loose packs or bales are inefficient in economic point of view. Pelleting rice straw can address that drawback by producing rice straw pellets with higher energy density and stabilized volumetric shape. However, rice straw in particular and other cereal crop residues in general have a low pelletizing ability which result in low mechanical strength of the product and high energy consumption of the process. To carefully understand the pelleting of rice straw, in this study a pelletizing system was developed to manufacture pellets from rice straw. In term of process condition, the dimension of the die representing ratio of compression was varied from L/φ = 60/10 to L/φ = 60/6 (mm/mm). In term of feeding conditions, pine sawdust was added with the ratio of 0%, 20% and 40% while sodium lignosulfonate was mixed with the ratio of 0%, 10% and 20%. Response surface models was applied to investigate the influences of independent variables on the physical properties and thermal characteristics including combustion behavior of rice straw pellets. It was found that with forming temperature higher than 100°C, moisture content was in the range of 15 to 18%, and the rotational speed of the die was approximate 300 rpm, the rice straw could be pelletized well. At the same conditions of forming temperature, moisture content, and rotational speed, compression ratio showed a positive effect on physical properties and thermal characteristics of rice straw pellets. However, increased compression ratio led to the increase of specific energy consumption of the pelleting process. Pine sawdust performed as a good additive when improved significantly the energy content and reduce the ash content of the rice straw pellets simultaneously, however it decreased the true density and bulk/tapped density of rice straw pellets in some cases. Sodium lignosulfonate showed a positive effect on physical properties with a restrained amount. However, it provided ash content and hence reduced the energy content of the rice straw pellets. Besides that, rice straw pellets performed as a good cooking fuels except some troubles came from feeding and de – ashing methods. The boiling water test of rice straw pellets on a non – grate traditional stove performed 17.88 % of stove efficiency. It might resulted from the high heating value and very low moisture content of the rice straw pellets produced. As a conclusion, pelletizing rice straw is possible and could produce the pellets with acceptable quality. However, further researches should focus on the design of the pelletizer and the pre – treatment of the rice straw as a pelletized feedstock to improve the production rate and reduce the specific energy consumption of the rice straw pelletization. |
| Year | 2016 |
| 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) | Salam, Abdul P.; |
| Examination Committee(s) | Kumar, Sivanappan;Nguyen, Thi Kim Oanh; |
| Scholarship Donor(s) | Daicuong Thermal Mechanical Limited Company, Vietnam;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2016 |