Development and Applications of a Novel Intermittent Solids Feeder for Pyrolysis Reactors

This PhD research addresses the challenge of feeding biomass residues into fluidized bed reactors for pyrolysis, through the development of a novel intermittent solid slug feeder, both for laboratory-scale and large-scale reactors. The new feeder can successfully handle biomass residues that are either too cohesive or thermally sensitive for traditional feeders. To optimize the novel feeder performance, a model for the pulsating solids flow was developed from experimental data collected with ideal slugs, as well as real biomass flow. The model was validated using both a laboratory-scale (\u3c 10 kg/hr) and large-scale feeder (\u3e 250 kg/hr). Several important variables were identified. They include the material flow properties, the pulse gas pressure and volume, and the feeding tube length and material. The goals of this study were to (a) characterize the fundamental dynamic behavior of the biomass slugs in the feeder, (b) maximize the solid-to-gas feeding ratio, and thus minimize energy consumption and cost, (c) minimize the accumulation of “straggler” biomass material in the feeding tube between pulses, and thus prevent biomass heating in the feeding tube, which can induce plugging, and (d) develop and validate a predictive model for the slug velocity at any location in the feeding tube, which can be applied to feeder design for any biomass feedstock. An advantage of the new large-scale feeder technology is that it can handle larger biomass particles than traditional feeder technologies. An issue with large particles is that they require relatively long drying, which must be optimized. A model was therefore developed for drying, which takes shrinkage, and internal and external mass transfer limitations into account. The thesis is supplemented with additional work based on the application of the novel feeder for pyrolysis studies with various biomass residues. The feeder technology made it possible to perform the first ever pyrolysis studies, in industrially-relevant equipment, on pure meat and bone meal residue, and on unmodified and undiluted Kraft lignin. Appendices include a business case-study of the implementation of the technologies developed in this thesis on large-scale pyrolysis and an additional pyrolysis study on tucumã seeds, which utilized the novel feeder

A BENCHMARK FOR TIP TIMING MEASUREMENT OF FORCED RESPONSE IN ROTATING BLADED DISKS

The Blade Tip-Timing is a well known non-contact measurement technique for the identification of the dynamic properties of rotating bladed disks. Even if it is an industrystandard technique its reliability has to be proved for the different operation conditions by comparison with other well stablished measurement techniques. Typically a strain gauges system in conjunction with radio telemetry is used as reference. This paper aims at evaluating the accuracy of a last generation Tip-Timing system on two bladed dummy disks characterized by different geometrical, structural and dynamical properties. Both the disks were tested into a spinning rig where a fixed number of permanent magnets, equally spaced around the casing, excites a synchronous resonance vibration with respect to the rotor speed. The so called beam shutter method was adopted for the Tip-Timing system. Due to the presence of shrouds a particularly set up of the probes was chosen in order to avoid that the probes look radially inward at the blade tips as in the most common configurations. he probes are optical laser sensors pointing at leading and trailing edges locations where the blade experiences the greatest magnitude of displacement. The Blade Tip-Timing measured data are post-processed by two different methods, the Single Degree of Freedom Fit (SDOF) and the Circumferential Fourier Fit (CFF). The amplitude and frequency values at resonance obtained by the Tip-Timing system are compared with those obtained by the strain gauge measurements

Hybrid Numerical-Experimental Model Update Based on Correlation Approach for Turbine Components

Bladed-disks in turbomachines experience high cycle fatigue failures due to high vibration amplitudes. Therefore, it is important to accurately predict their dynamic characteristics including the mechanical joints at blade-disk interfaces. Before the experimental identification of these joints, it is of paramount importance to accurately measure the interface degrees-of-freedom (DoF). However, they are largely inaccessible for the measurements. For this reason, expansion techniques can be used in order to update the single components. But the expansion can be affected adversely if the measurements are not properly correlated with the updated model. Therefore, a frequency domain expansion method called System Equivalent Model Mixing (SEMM) is used to expand a limited set of measurements to a larger set of numerical DoF. Different measured models—termed the overlay models—are taken from an impact testing campaign of a blade and a disk and coupled to the numerical model according to the SEMM. The expanded models—termed the hybrid models—are then correlated with the validation channels in a round-robin way by means of Frequency Response Assurance Criteria (FRAC). The global correlations depict whether or not a measurement and the respective expansion is properly correlated. By this approach, the least correlated channels can be eliminated from the measurements to have a better updated hybrid model. The method is tested on both the structures (the blade and the disk) and it is successfully shown that removing the uncorrelated channels does improve the quality of the hybrid models