Solids concentration meters

This section is separated into the various categories of instruments, such as flow meters, solids concentration meters and timers. Lastly, controllers will be covered. 

Flow meters for aqueous slurries are reliable, accurate and seldom require adjustment after initial calibration. Moreover they are amenable for connection to PLCs, computers and controllers. The most common models used on decanter plants are eddy current and ultrasonic type. Flow meters are used on the feed line after the feed pump and similarly on the polymer line. 

Flow measurement is employed on the oil lubrication lines, but is usually of the rotameter, or variable orifice type. This means that they are used for indication only, and are not readily coupled into the control system, unless simply as alarm features. 

Ideally, a flow meter should be fitted on the thickened cake recycle line. This is because the solids monitor works on the principle that the cake solids concentration is a function of viscosity, which in turn is monitored as a pressure drop when flowing. Thus the flow rate also affects the pressure drop, and therefore must be kept constant. However, often it is found that plant users rely on the constant rate from a metering pump, making periodic adjustments to flow or calibration should the pump wear. 

The total flow of thickened cake is usually obtained by calculation, but a check can be made by measuring the time intervals between discharge of the sump tank. This would be how the oil flow is measured from a three-phase decanter. 

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Amazon deltaic deposits are reworked extensively by tides and waves (Geyer et al. 1996, Kineke et al. 1996, Sternberg et al. 1996). Over 10% of the Amazon subaqueous delta is covered by fluid muds (suspended solid concentration > 10 g L O, which can be several meters thick in some places. These sediments and the water contained therein can be mobilized by changes in frontal dynamics or by fortnightly tidal cycles (Kineke et al. 1996, Geyer et al. 1996). Even in nonfluid mud areas, the sediment can be... 

The feed materials are manufactured and shipped at paint solid concentrations ranging from 40% to 99+%. In some installations, the feed is metered into the tank in the form of two or more components, one component being the resin, the other component being a pigment slurry, etc. 

The meter does not require accurate calibration, since it is only necessary to measure relative velocities at different impeller speeds, and the position of the endpoint is taken as an indication of Njg. For successful operation a fairly high solids concentration is needed, at least 2 to 3 vol %. At lower concentrations the instrument can see right through the bed of solids and does not detect an endpoint. Several different types of sensing heads are available which measure velocities at various distances from the vessel waU. A head with as small a measuring distance as possible should be used to prevent this problem. 

Dye adsorption from solution may be used to estimate the surface area of a powdered solid. Suppose that if 3.0 g of a bone charcoal is equilibrated with 100 ml of initially 10 Af methylene blue, the final dye concentration is 0.3 x 10 Af, while if 6.0 g of bone charcoal had been used, the final concentration would have been 0.1 x Qr M. Assuming that the dye adsorption obeys the Langmuir equation, calculate the specific surface area of the bone charcoal in square meters per gram. Assume that the molecular area of methylene blue is 197 A. ... 

Segmental and eccentric orifices are frequently used for gas metering when there is a possibility that entrained liqiiids or solids would otherwise accumulate in front of a concentric circular orifice. This can be avoided if the opening is placed on the lower side of the pipe. For hquid flow with entrained gas, the opening is placed on the upper side. The pressure taps should be located on the opposite side of the pipe from the opening. 

Fig. 21-7, Relative concentration in seconds per meter (s m ) exceeded in a 10-km city on 10% of all mornings (solid lines) and 10% of all afternoons (dashed lines). Source After Holzworth (2),...

Procedure. The test solution should contain between 0.001 and 0.02 mg of cobalt. Evaporate almost to dryness, add 1 mL of concentrated nitric acid, and continue the evaporation just to dryness to oxidise any iron(II) which may be present. Dissolve the residue in 10 mL of water containing 0.5 mL each of 1 1 hydrochloric acid and 1 10 nitric acid. Boil for a few minutes to dissolve any solid material. Add 2.0 mL of a 0.2 per cent aqueous solution of nitroso-R-salt and also 2.0 g of hydrated sodium acetate. The pH of the solution should be close to 5.5 check with bromocresol green indicator or with a pH meter. Boil for 1 minute, add 1.0 mL of concentrated hydrochloric acid, and boil again for... 

Once the student had determined the exact concentration of the base, the student then proceeded to determine the equivalent mass of an unknown acid. To do this, the student measured out 0.500 grams of an unknown solid acid and titrated it with the standardized base, recording pH with a calibrated pH meter as the base was added. The student added 43.2 mL of the base but went too far past the end point and needed to back-titrate with 5.2 mL of the 0.100 M HC1 to exactly reach the end point. 

The airborne monitoring program concentrated on the measurement of ozone to provide supplementary air quality data for various altitudes over the fixed sites. The airborne measurements were conducted in a C-45 aircraft that carried a solid-face chemiluminescent ozone monitor. The ozone meter was cycled every 2 min to provide calibration, purge, measurement, and purge at equal intervals. The sparseness of the airborne data precluded... 

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