Influence of Water Velocity on Marine Immersion Corrosion of Mild Steel

CORROSION ◽  
2004 ◽  
Vol 60 (1) ◽  
pp. 84-94 ◽  
Author(s):  
R. E. Melchers ◽  
R. Jeffrey
Keyword(s):  
Mild Steel ◽  
Water Velocity ◽  
Immersion Corrosion ◽  
Influence Of Water

High nitrification rate with upflow biofiltration

1996 ◽  
Vol 34 (1-2) ◽  
pp. 347-353 ◽  
Author(s):  
J.-G. Peladan ◽  
H. Lemmel ◽  
R. Pujol
Keyword(s):  
Contact Time ◽  
Pilot Scale ◽  
Ammonium Nitrogen ◽  
Water Velocity ◽  
Nitrification Rate ◽  
Air Velocity ◽  
Influence Of Water ◽  
Hydraulic Load ◽  
Series Of Experiments ◽  
Positive Effect

In order to investigate the upper limit of aerated biofilm processes, a series of experiments has been carried out on a pilot scale with a synthetic effluent containing only ammonium nitrogen and inorganic carbon as substrates. The influence of water velocity, air velocity and media height has been studied without the interaction of organic carbon and suspended solids. Under these conditions, the increase of the hydraulic load has a positive effect on the maximum nitrified load, despite the shortening of contact time. The pilot plant was able to nitrify 2.7 kg NH4+-N/m3.d at 14° C with an empty bed hydraulic retention time as short as 6 minutes - under a 30 m3/m2.h hydraulic load. It was also demonstrated that a cubic meter of granular bed presents the same nitrification capacity in a 3 m or in a 4 m media high biofilter, only if placed under the same conditions of air and water velocities. The results confirmed that water velocity significantly improves substrate bulk/biofilm transfer, and demonstrated that neither a contact time - based on the pore volume - as short as 2 minutes nor a media height of 4 m limit the nitrification rate.

Combined filter for ammonia removal – part I: Minimal zeolite contact time and requirements for desorption

1999 ◽  
Vol 39 (8) ◽  
pp. 123-129 ◽  
Author(s):  
G. Dimova ◽  
G. Mihailov ◽  
Tz. Tzankov
Keyword(s):  
Ion Exchange ◽  
Contact Time ◽  
Water Hardness ◽  
Ammonia Concentration ◽  
Water Velocity ◽  
Ammonia Removal ◽  
Design Parameters ◽  
Influence Of Water ◽  
Minimal Contact ◽  
Differential Element

The minimal contact time in removal of ammonia ions by ion-exchange with zeolite, Na-form, is determined using the method of differential element. The relationship between the contact time, the water velocity, the effect of removal and the initial ammonia concentration is investigated. The obtained data serve as a basis for mathematical modeling of the ion exchange kinetics and give valuable information about some design parameters of ion-exchange facilities. Some basic analyses, concerning the desorption of ammonia from zeolite, induced mainly from the cations naturally present in surface waters are made. The influence of water velocity and water hardness on such desorption is investigated. These experimental data and analyses are an essential part of a study, the purpose of which is to investigate the possibilities for ammonia removal and biological regeneration of zeolite in a combined facility, using the processes: ion-exchange, desorption induced by small concentrations of cations and biological nitrification.

scholarly journals Influence of Water Temperature on Results of Current Meter Calibration and Measurement

2013 ◽  
Vol 61 (3) ◽  
pp. 208-213 ◽  
Author(s):  
Daniel Mattas ◽  
Libuše Ramešová
Keyword(s):  
Water Temperature ◽  
Rotational Velocity ◽  
Rotational Frequency ◽  
Water Velocity ◽  
Uncertainty Of Measurements ◽  
Influence Of Water ◽  
Type 3 ◽  
Measured Water ◽  
Term Data

Abstract On the basis of the results of calibration of current meters at water of varying temperatures, a hypothesis that water temperature influences measured water velocities was formulated. The analysis of our long-term data showed that the water temperature does have an influence on measured water velocity. This influence can be taken into account for practical purposes as a contribution to the uncertainty of measurements. The influence depends on the type of current meter propeller. This paper presents results obtained for the Ott C-2 current meter with propellers of the types 1, 2, 3, 5 and 6. Our analysis showed that the uncertainty is equal or less than 5% for measurements carried out in water with temperatures above 8°C. The differences between measured water velocities for water temperatures 5°C and 20°C reached maximum 6% (depending on the propeller) in a slowly flowing water (rotational frequency n = 1 s-1). For rotational velocity n ≥ 2 s-1 the differences between velocities measured at water temperatures 5 and 20°C were mostly under 3%. The less influenced propeller is of type 3 for which the uncertainty of measurement does not reach 5% even for water temperature 1°C if the rotational frequency is bigger than 0.7 s-1.

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