Dr. Ashutosh Patel
B. Tech., M. Tech., Ph. D. (Tech)
| Education Details | ||
Course |
Institute/University |
Year of Passing |
| B. Tech. Chemical Engineering |
2000 |
|
| M. Tech. Environmental Engineering | M. S. Baroda, Gujrat | 2002 |
| Ph. D. Tech. Chemical Engineering |
University Institute of Chemical Technology, UICT, Mumbai | 2006 |
Abstract of Ph. D. Thesis:
DESIGN OF MULTIPHASE REACTORS: RADIOISOTOPES APPLICATION FOR TROUBLESHOOTING AND PROCESS OPTIMIZATION IN CHEMICAL INDUSTRY
The indepth knowledge of multiphase reactor hydrodynamics is needed for its design and development of an optimized and trouble free operation. Gas hold-up distribution is one of the important hydrodynamic parameters in the multiphase system. As it generate density gradient within the system, it leads to phase movement which intern governs the rate of mixing and heat & mass transfer. Gas hold-up information also facilitates the determination of flow regimes. Therefore, it is necessary to understand the change in gas hold-up distribution as a function of various geometric and process variables. The g-ray tomography which comprises of data acquisition as well as data processing was developed to study the gas hold-up distribution in various multiphase system, lab scale as well as industrial scale. Data processing was done using two iterative image reconstruction techniques namely, algebraic reconstruction technique and maximum likelihood – expectation minimization algorithm. Several image reconstruction parameters such as; initial guess, grid size, and beam configuration were studied in detail in order to achieve greater reliability of the technique.
Bubble Column: g-ray tomography was carried out over a cylindrical bubble column of 0.2 m i.d. and 1.2 m height for air – water system. Perforated plates having 0.136- 1% free area and 1-3 mm hole diameter with and without cloth (pore size = 8-20 mm) on it were used as gas distributors. Superficial gas velocity was varied in the range of 0 – 0.2 m/s. The objective was to obtain the gas hold-up distribution profile along the axial as well as along the radial directions. These measurements were carried out using 1 millicurie 137Cs as a g-radiation source and a collimated NaI scintillator detector. The average fractional gas hold-up in bubble column was estimated using bed expansion method. g-ray tomography was carried out at HD /D= 0.785 and 2.75.
Draft tube Bubble Column: g-ray tomography measurements for gas hold-up profile was also carried out in draft tube bubble column. The draft tube bubble column was made of riser (0.3 m i.d. & 0.615 m height) and downcomer (0.57 m i.d. & 1.8 m height) with a four arm cum ring sparger (% free area = 0.5) located at the bottom of coaxially placed draft tube. The effect of sparger design, clearance between the draft tube and sparger and the superficial gas velocity on gas hold-up profile was studied. This gas hold-up data was further used to obtain the liquid circulation velocities which were then compared with the mixing time study carried out with the help of tracer experiments.
Batch Fluid Bed System: g-ray tomography of batch fluid bed (0.15 m i.d. & 0.4 m height) was carried out to study the performance of gas distributor in terms of degree of uniform fluidization. The study included the effect of material characteristics such as particle size, particle density, moisture content and process variables such as superficial gas velocity, bed height and solid loading on degree of uniform fluidization by measuring the solid hold-up profile. The experiments were carried out using three different materials having wide physico-chemical properties.
Industrial Scale g-ray Tomography: Tomography measurements were also carried out in three different types of industrial scale multiphase systems such as, sectionalized bubble column reactor (0.5 m3), packed distillation column (0.55 m i.d.) and 500 L fluidized bed dryer. The study was carried out as an exercise to debottleneck some of the key parameters related to the system hardware such as blockage of holes and uneven distribution through the sparger plate causing undesired maldistribution.