Particle Holdup and Average Residence Time in the Cyclone of a CFB Boiler

2008 ◽  
Vol 31 (2) ◽  
pp. 224-230 ◽  
Author(s):  
S. H. Li ◽  
S. Yang ◽  
H. R. Yang ◽  
H. Zhang ◽  
Q. Liu ◽  
...  
Keyword(s):  
Residence Time ◽  
Average Residence Time ◽  
Cfb Boiler

Study on the continuous precipitation of U(IV) oxalate in a vortex precipitator

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chuanbo Li ◽  
Yongzhi Ning ◽  
Taihong Yan ◽  
Weifang Zheng
Keyword(s):  
Oxalic Acid ◽  
Residence Time ◽  
Nitrate Solution ◽  
The Other ◽  
Nucleation Process ◽  
Average Residence Time ◽  
Continuous Precipitation ◽  
Vortex Zone ◽  
Forced Vortex ◽  
Particles Size Distribution

Abstract The effects of feeding location, stirring speed and apparent average residence time on oxalate crystals size and distribution, tackiness of the product on the walls of reactor and stirring paddle were investigated in a vortex continuous precipitator at 45 °C. The results showed agglomeration happened during nucleation and crystals growth of U(IV) oxalate. Both local supersaturations and agglomeration maked the particles size distribution of U(IV) oxalate from 10–100 µm and the average sizes 35–45 µm. On the other hand, when the nucleation process were controlled to happen in the forced vortex zone, two feeding locations: (a) both oxalic acid and U(IV) nitrate solution into the forced vortex zone, (b) oxalic acid into the free vortex and U(IV) nitrate solution into the forced vortex, tackiness of the crystals on the wall of the precipitator could be effectively avoided.

Simulation of water exchange in Jiaozhou Bay by average residence time approach

2004 ◽  
Vol 61 (1) ◽  
pp. 25-35 ◽  
Author(s):  
Zhe Liu ◽  
Hao Wei ◽  
Guangshan Liu ◽  
Jing Zhang
Keyword(s):  
Residence Time ◽  
Water Exchange ◽  
Jiaozhou Bay ◽  
Average Residence Time

scholarly journals The residence time of water in the atmosphere revisited

2017 ◽  
Vol 21 (2) ◽  
pp. 779-790 ◽  
Author(s):  
Ruud J. van der Ent ◽  
Obbe A. Tuinenburg
Keyword(s):  
Residence Time ◽  
Hydrological Cycle ◽  
State Of The Art ◽  
Average Residence Time ◽  
Atmospheric Moisture ◽  
Atmospheric Water ◽  
Time And Space ◽  
Global Average ◽  
High Precipitation ◽  
Global Mean

Abstract. This paper revisits the knowledge on the residence time of water in the atmosphere. Based on state-of-the-art data of the hydrological cycle we derive a global average residence time of 8.9 ± 0.4 days (uncertainty given as 1 standard deviation). We use two different atmospheric moisture tracking models (WAM-2layers and 3D-T) to obtain atmospheric residence time characteristics in time and space. The tracking models estimate the global average residence time to be around 8.5 days based on ERA-Interim data. We conclude that the statement of a recent study that the global average residence time of water in the atmosphere is 4–5 days, is not correct. We derive spatial maps of residence time, attributed to evaporation and precipitation, and age of atmospheric water, showing that there are different ways of looking at temporal characteristics of atmospheric water. Longer evaporation residence times often indicate larger distances towards areas of high precipitation. From our analysis we find that the residence time over the ocean is about 2 days less than over land. It can be seen that in winter, the age of atmospheric moisture tends to be much lower than in summer. In the Northern Hemisphere, due to the contrast in ocean-to-land temperature and associated evaporation rates, the age of atmospheric moisture increases following atmospheric moisture flow inland in winter, and decreases in summer. Looking at the probability density functions of atmospheric residence time for precipitation and evaporation, we find long-tailed distributions with the median around 5 days. Overall, our research confirms the 8–10-day traditional estimate for the global mean residence time of atmospheric water, and our research contributes to a more complete view of the characteristics of the turnover of water in the atmosphere in time and space.

Stationary increments of accumulation processes in queues and generalized semi-Markov schemes

1991 ◽  
Vol 28 (4) ◽  
pp. 864-872 ◽  
Author(s):  
R. D. Foley ◽  
Georgia-Ann Klutke ◽  
Dieter König
Keyword(s):  
Markov Process ◽  
Response Time ◽  
Residence Time ◽  
Additive Functional ◽  
Sufficient Condition ◽  
Average Residence Time ◽  
Service Requirement ◽  
Conditional Average ◽  
Stationary Increments

Let Tx be the length of time to accumulate x units of a resource. In queueing, the resource could be service. We derive a sufficient condition for the process to have stationary increments where Tx is an additive functional of a Markov process. This condition is satisfied in symmetric queues and generalized semi-Markov schemes with insensitive components. As a corollary, we show that the conditional expected response time in a symmetric queue is linear in the service requirement. A similar result holds for the conditional average residence time of an insensitive component in a GSMS.

Processing of Biowaste by Anaerobic Composting to Plant Growth Substrates

1993 ◽  
Vol 27 (2) ◽  
pp. 109-119 ◽  
Author(s):  
J. Vermeulen ◽  
A. Huysmans ◽  
M. Crespo ◽  
A. Van Lierde ◽  
A. De Rycke ◽  
...  
Keyword(s):  
Plant Growth ◽  
Production Rate ◽  
Residence Time ◽  
Biogas Production ◽  
Organic Fertilizer ◽  
Process Time ◽  
Average Residence Time ◽  
Anaerobic Biodegradability ◽  
Growth Substrates ◽  
Biogas Production Rate

Kitchen derived biowaste was fermented in a 40 1 digester at 55°C with a loading of 5.2 g VS/l.d and an average residence time of 42 days. This resulted in an average biogas production rate of 3.6 1/l.d. Different types of paper were investigated for their anaerobic biodegradability; the conversion on VS-basis ranged from 17 % for a regular newsprint to 100 % for a bleached cellulose. A reactor, fed with biowaste supplemented with paper, was operated at 55°C and a loading rate of 12.6 g VS/l.d; this corresponded with an average residence time of 20 days and an average biogas production rate of 7.14 1/l.d. The addition of paper lowered the NH4+−N level from 3.5 g/kg wet material to 1.65 g/kg wet material. Compared to MSW-digest, the biowaste-digest was found to be a NPK rich organic fertilizer with low levels of heavy metals. The moist digest was supplemented with 40 % peat(w/w) to attain 25 % dry matter and subsequently allowed to compost aerobically during 7 days at ambient temperature to a mature endproduct. Horticultural plants were grown on various endproduct/peat mixtures. The latter exhibited no phytotoxicity and performed in some cases better than optimal reference substrates. The blending of the wet digest with peat thus allows to obtain in a very short process time an excellent plant substrate. Furthermore, peat also demonstrated its quality as odour absorbant. It instantaneously reduced the odour units of digested biowaste by a factor of 50. These tests indicate that biowastes can be elegantly transformed into plant growth substrates of high quality by supplementing them with paper waste in the anaerobic digestion phase and by peat in the subsequent aerobic maturation phase.

Gas hydrodynamics of a novel MTO high-speed loop reactor: The bypassing and backmixing along with average residence time

2020 ◽  
Vol 364 ◽  
pp. 1062-1075 ◽  
Author(s):  
Fenfen Wang ◽  
Shihan Ma ◽  
Jiajia Wen ◽  
Chenglin E. ◽  
Chunxi Lu
Keyword(s):  
Residence Time ◽  
High Speed ◽  
Average Residence Time ◽  
Loop Reactor

Bacterial residence time in the intestine of Caenorhabditis elegans

Nematology ◽  
2007 ◽  
Vol 9 (1) ◽  
pp. 87-91 ◽  
Author(s):  
James McGhee ◽  
Shervin Ghafouri
Keyword(s):  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Residence Time ◽  
High Rate ◽  
Average Residence Time ◽  
Dilution Curve ◽  
Fluorescent Microspheres ◽  
First Order ◽  
C Elegans ◽  
Total Fluorescence

AbstractWe fed adult Caenorhabditis elegans fluorescent microspheres mixed with their Escherichia coli food and then measured the total fluorescence of expelled faeces as a function of time after transfer to unlabelled bacteria. Intestinal clearance obeys a simple first-order decay or dilution curve: we estimate that 43 ± 10% of the maximum intestinal volume is expelled in each defecation and the average residence time of a bead (by inference, a bacterium) is less than 2 min. Our results raise questions how bacteria can be sufficiently digested in this brief period to provide energy and material to sustain the high rate of C. elegans oocyte production.

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