- Title
- Dense phase pneumatic conveying of biomass
- Creator
- Rajabnia, Hossein
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The increasing demand for efficient handling methods in the biomass material utilisation field has led to the exploration of dense phase pneumatic conveying as a promising solution. However, the unique properties of biomass materials make the conveying process more complex, and there has been limited research on its characteristics. This thesis delves into the experimental and theoretical investigation of dense phase pneumatic conveying for four biomass materials: cottonseed, wood chips, wood pellets, and wheat straw, which possess unique properties that distinguish them from typical granular materials. The investigation addresses the research gap by exploring three distinct aspects: characterising the behaviour of biomass materials, examining the dynamics of dense phase conveying, and predicting pressure drops within the system. To accomplish these objectives, three experimental setups were developed, comprising aeration and deaeration tests, single batch conveying, and continuous pneumatic conveying using a rotary valve. Over 200 tests were conducted in total to achieve the goals of this study. During the comprehensive experiments in the characterisation phase, it was discovered that all four materials were suitable for plug flow. Cottonseed and wheat straw showed a higher propensity to form stable plugs in vertical pipelines, while all four materials were capable of plug flow in horizontal configurations. The analysis of aeration and deaeration pressure drops over the beds exhibited an exponential behaviour with a time constant. A notable finding from this part of the study was that the ratio of aeration to deaeration time constants is a unique value that can determine plug/no plug behaviour. A ratio closer to one indicates a higher likelihood of forming a stable plug. The dynamics of plug flow were investigated through two distinct aspects. In the first aspect, the initiation of cottonseed plugs was examined using the analogy of an RC circuit, introducing the concept of potential pressure drop, which is defined as the pressure drop across a plug while it is theoretically forced to remain stationary. The results revealed a linear relationship between the difference in potential pressure drop and the measured pressure drop with the plug velocity. In the second aspect, the theoretical stability of a multi-plug system was explored, demonstrating that individual slugs within systems of multiple slugs tend to be unstable. Consequently, modelling and analysis of such systems should account for these inherent unstable conditions found in multiple slug systems. Furthermore, a pressure model is proposed, and its capability is investigated through various test configurations. The results demonstrated that the model can predict pressure drops for these biomass materials with an error margin of 30 percent. Additionally, through comprehensive data analysis, different subsets of trained data were selected using combinations of 3 to 7 trials. It was found that conducting three trial tests has at least a 60 percent probability of predicting the validation data as accurately as performing seven times more trial tests. The remarkable contribution of this pressure model is its potential to significantly reduce the number of trial tests required for predicting pressure drops within the system. In conclusion, this study represents one of the pioneering efforts in the field of dense phase pneumatic conveying of biomass materials. While significant progress has been made in understanding the behaviour, dynamics, and pressure drop prediction of biomass materials, there is still considerable scope for further research and development. Future work in this area will continue to enhance the efficiency and reliability of dense phase pneumatic conveying systems for biomass, paving the way for more sustainable and effective biomass handling solutions.
- Subject
- pneumatic conveying; biomass; aeration; deaeration; dense phase; plug flow; fluidisation
- Identifier
- http://hdl.handle.net/1959.13/1504922
- Identifier
- uon:55598
- Rights
- Copyright 2023 Hossein Rajabnia
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 31 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 292 KB | Adobe Acrobat PDF | View Details Download |