Solids metering

Solids Metering The control valves described earlier are primarily used for the control of fluid (liquid or gas) flow. Sometimes these valves, particularly the ball, butterfly, or sliding gate valves, are used to throttle dry or slurry solids. More often, special throttling mechanisms such as venturi ejectors, conveyers, knife-type gate valves, or rotating vane valves are used. The particular solids-metering valve hardware depends on the volume, density, particle shape, and coarseness of the solids to be handled. 

AccuRate Bulk Solids Metering Unit of Schenck AccuRate 746 East Milwaukee Street P.O. Box 208 WMtwater, WI 53190, USA tel 1 414 473 2441 toll free 1 800 558 0184 fax 1 414 473 4384 solid metering 220... 

Accuratus Ceramic Corporation, 14A Brass Castle Road, Washington, NJ 07882, USA Ace International Inc., 520 North Gold Street, Centralia, WA 98531-0885, USA ACuPowder International, LLC, 901 Lehigh Avenue, Union, NJ 07083, USA AccuRate Bulk Solids Metering, Unit of Schenck AccuRate, 746 East Milwaukee Street, P.O. Box 208, Whitwater, WI 53190, USA... 

The change in flight depth along the screw (i.e., the ratio of the solids metering channel depth to the melt pump channel depth) is known as the... 

The polymer control system can be augmented with a feed solids meter, to give "feed-forward control, fixing the kg/t db polymer usage to an operator set point. 

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. ... 

Selenium exhibits both photovoltaic action, where light is converted directly into electricity, and photoconductive action, where the electrical resistance decreases with increased illumination. These properties make selenium useful in the production of photocells and exposure meters for photographic use, as well as solar cells. Selenium is also able to convert a.c. electricity to d.c., and is extensively used in rectifiers. Below its melting point selenium is a p-type semiconductor and is finding many uses in electronic and solid-state applications. 

FIG. 5-13 Hemispherical and normal emissivities of metals and their ratio. Dashed lines monochromatic (spectral) values versus r/X. Solid lines total values versus rT To convert ohm-centimeter-kelvins to ohm-meter-kelvins, multiply hy 10"l... 

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. 

Farbar [Trans. Am. Soc. Mech. Eng., 75,943-951 (1953)] describes how a venturi meter can be used to measure solids flow rate in a gas-solids mixture when the gas rate is held constant. Separate calibration curves (solids flowversus differential) are required for each gas rate of interest. 

Liquid-Solid Mixtures Liptak [Chem. Eng., 74(4), 151-158 (1967)] discusses a variety of techniques that can be used for the measurement of sohds-in-liquid suspensions or slurries. These include metering pumps, weigh tanks, magnetic flowmeter, ultrasonic flowmeter, gyroscope flowmeter, etc. 

FIG. 10-26 Pump coverage chart based on normal ranges of operation of commercially available types. Solid lines use left ordinate, bead scale. Broken lines use right ordinate, pressure scale. To conveii gallons per minute to cubic meters per hour, multiply by 0.2271 to conveii feet to meters, multiply by 0.3048 and to conveii poiinds-force per square inch to Idlopascals, multiply by 6.895. 

When consistent units are used, the particle size will either be in meters or feet. The equation contains effects of cyclone size, velocity, viscosity, and density of solids. In practice, a design curve as given in Fig. 17-39 uses Dptk the size at which 50 percent of sohds of a given size are collected by the cyclone. The material entering the cyclone is divided into fractional sizes, and the collecdion efficiency for each size is determined. The total efficiency of coUection is the sum of the col-lecdion efficiencies of the cuts. 

Loading of Solids in Inlet Gas, Kg of Solids/Cubic Meter of Gas... 

Bulk den.situ. This is the weight per unit of volume of a quantity of solid particles, usually expressed in kilograms per cubic meter (pounds per cubic foot). It is not a constant and can be decreased by aeration and increased by vibration or mechanical packing. 

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),...

Turbidity Legislation and controls ASTM method Turbidity meter (see also Suspended solids)... 

Petrochemical units generate waste waters from process operations such as vapor condensation, from cooling tower blowdown, and from stormwater runoff. Process waste waters are generated at a rate of about 15 cubic meters per hour (m /hr), based on 500,000 tpy ethylene production, and may contain biochemical oxygen demand (BOD) levels of 100 mg/1, as well as chemical oxygen demand (COD) of 1,500 to 6,000 mg/1, suspended solids of 100 to 400 mg/1, and oil and grease of 30 to 600 mg/1. Phenol levels of up to 200 mg/1 and benzene levels of up to 100 mg/1 may also be present. 

PI 9 Other Liquid Phase Separation mass) for solids and liquids cubic centimeters/cubic meter ... 

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