A residence time is the average time a substance spends within a specified region of space, such as a reservoir. For example, the residence time of water stored in deep groundwater, as part of the water cycle, is about 10,000 years. A common method for determining residence times is to calculate how long it would take for a region of space to become filled with a substance. Water is a tasteless, odorless substance that is essential to all known forms of life and is known as the universal solvent. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ... The movement of water around, over, and through the Earth is called the water cycle. ...
The age, or residencetime, of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways, and source of water in a single integrated measure.
While there has been tremendous recent interest in residencetime estimation to characterize watersheds, there are relatively few studies that have quantified residencetime at the watershed scale, and fewer still that have extended those results beyond single catchments to larger landscape scales.
Residencetimes were estimated by simple convolution models that described the transfer of precipitation isotopic composition to the stream network.
The total slurry residencetime is the time during which the reaction slurry is within the temperature range of this invention, and is based upon the total volume of the slurry, measured under ambient conditions, passing through the reaction assuming that the small volume occupied by gas is negligible.
The total slurry residencetime is continuously controlled by continuously and directly quenching the reaction effluent, i.e., direct intermixing of the reaction effluent with a quenching fluid to substantially immediately reduce the temperature sufficiently to substantially terminate or inhibit polymerization and hydrocracking reactions, e.g., to a temperature below about 425.degree.
At a 6 minute residencetime, the recycle solvent loss was 7.1 weight percent (on a MF coal basis) in the single pass mode, whereas the loss decreased to 0.7 weight percent in the solvent recycle run.
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