China
Africa
Explore chapters and articles related to this topic
Coastal geomorphology
Published in Richard J. Chorley, Stanley A. Schumm, David E. Sugden, Geomorphology, 2019
Richard J. Chorley, Stanley A. Schumm, David E. Sugden
(3) Estimates from use of tracers or ‘tagged debris’, such as painted or radioactive pebbles and sand, have been used. The relatively short radioactive decay times (phosphorus-32, halflife 14.6 days, traceable for several months; barium 140-lanthanum 140, halflife 12 days, traceable for up to 7 weeks) restrict observations, but the major difficulty is that the marked material is only a very small proportion of that moving on the beach, making recovery and interpretation difficult. Burial at depths greater than 23 cm makes the material difficult to trace. Empirical work suggests that mean grain velocities Vg are about one-sixth of the mean longshore current velocity Vland that there is a simple linear relation between the former and the net longshore energy flux El (Figure 15.16).
Application of tracer technology in wastewater treatment processes: a review
Published in Chemical Engineering Communications, 2023
Metali Sarkar, Vikas Kumar Sangal, Harish Jagat Pant, Vijay Kumar Sharma, Haripada Bhunia, Pramod Kumar Bajpai
The application of radiotracer for analyzing WWTP reactors is growing rapidly due to its many advantages over commonly used conventional tracers (Pant et al. 2001; IAEA 2008). Radiotracers have high detection sensitivity and facilitate online measurements. As every radiotracer emits radiation of distinct frequency, this facilitates the study of multiphase reactor processes simultaneously by employing multiple radiotracers. Radiotracer Bromine- 82 (82Br) and Iodine-131 (131I) have been frequently used for liquid phase tracing in WWTP systems (Shin et al. 2003; Kumar et al. 2012). For solid-phase tracing conventionally Gold-198 (198Au), Lanthanum-140 (140La), and Technetium (99mTc) (Friedrich 1983; Pant et al. 2009; Kumar et al. 2012). Commonly used radiotracer in WWTP processes has been listed in Table 2 according to their field of application.
Residence time distribution studies using radiotracers in chemical industry—A review
Published in Chemical Engineering Communications, 2018
Meenakshi Sheoran, Avinash Chandra, Haripada Bhunia, Pramod K. Bajpai, Harish J. Pant
The catalyst dynamics of Fluid catalytic cracking unit (FCCU) of two different refineries was investigated by Pant et al. (2009c). The catalyst samples were activated through instrumental neutron activation analysis. Twelve different components of the catalyst were activated, but the radioactivity of the lanthanum and sodium was observed to be highest as compared to the other elements on the catalyst. It was also observed that lanthanum (140La) and sodium (24Na) were present in higher concentration than other elements. The catalyst dynamics of Fluid These irradiated samples were used as an intrinsic radiotracer to find out the MRT of catalyst and axial mixing in the FCCU. The radial distribution in riser and stripper was measured the radiotracer concentration curve obtained from detectors mounted across the diameter of the column at different axial locations. This type of measurement is possible only using radiotracer technique. The ADM was used to model the experimental data and high axial mixing was observed in the riser which was undesirable (Pant et al., 2009c).