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Air Pollution Control 101
Published in Kenneth Schifftner, Air Pollution Control Equipment Selection Guide, 2021
Standard air is usually taken as a mixture of about 79% by volume nitrogen, 21% by volume oxygen, 0.04% carbon dioxide, and the rest argon and trace gases. In English units, the density at 1 atmosphere (sea level) and 68°F (20°C) and 50 RH (relative humidity) is about 0.075 lbs/ft3. Gas flows through air pollution control devices are often defined in terms of standard cubic feet per minute (scfm). To complicate things, sometimes the scfm is calculated at 60°F or 70°F; sometimes sdcfm or dscfm is used, indicating that the gas flow is defined totally dry (no water vapor). This term is handy because the dry gas mass flow through a gas cleaning device does not change, though its volume may change given pressure and/or temperature differences. The standard air mixture typically has a specific heat of 0 24 BTU/lb.
Mass and Volume Flow Measurements
Published in Ethirajan Rathakrishnan, Instrumentation, Measurements, and Experiments in Fluids, 2020
It should be noted that the commercial gas flow meters specify the flow rate as volume flow rate at standard conditions of 1 atm and 20°C. The units employed are standard cubic feet per minute (scfm) and standard cubic centimeters per minute (sccm). In this chapter we will be discussing some of the popularly employed techniques and devices for flow measurements.
Mass and Volume Flow Measurements
Published in Ethirajan Rathakrishnan, Instrumentation, Measurements, and Experiments in Fluids, 2016
It should be noted that the commercial gas flow meters specify the flow rate as volume flow rate at standard conditions of 1 atm and 20° C. The units employed are standard cubic feet per minute (scfm) and standard cubic centimeters per minute (sccm). In this chapter we will be discussing some of the popularly employed techniques and devices for flow measurements.
Effect of magnetic field on a loosely packed, tightly packed and an over-tightly packed metal powder bed
Published in Particulate Science and Technology, 2021
Kavin Sundarnath J. Ayyanathan, Sarada Kuravi
The pressure drop measurements inside a metal powder bed were made for decelerating compressed airflow, with and without the external magnetic field for the three packed bed samples of iron (III) oxide powder. The setup that was constructed to measure the pressure drop across the packed bed is shown in Figure 1 and the corresponding schematic is shown in Figure 2. A compressed air supply with a peak pressure value of 150 psig is used in the experiment to supply the working fluid. The inlet valve is open to higher flow rate of 29.5 SCFM and measurements are taken from 29 SCFM to 27 SCFM at 0.5 SCFM intervals, as the flow rate goes down. The deceleration was estimated to be 0.001 m/s2 by measuring the time it takes for the flow rate to go down by 1 SCFM. A tape heater was wrapped around a 0.5-inch (12.7 mm) aluminum tube for a length of 18 inches (457.2 mm) to heat the air if the temperature drops much below the room temperature, which is possible as the compressor is located outside the building and supplied through metal piping and valves. All measurements in the experiment were made at the inlet temperature of 21 °C, which is same as the room temperature. After the exit from the heater, the compressed air is then expanded through a PVC elbow into 2-inch PVC piping along which the bed is placed. Here, the temperature drops to 20.5 °C due to expansion. A flow straightener is placed before the packed bed to attain parallel flow in the air stream. The flowrate and velocity are measured separately using RCM industries’ flowmeter (3% accuracy) and Omega’s FMA 1000 series (velocity indicator) respectively. The pressure drop measurements were carried out using two pressure gauges, Omega’s DPG4000 series gauge (0.05% accuracy, P1) at the inlet of the bed and Omega’s DPG7000-300 (0.05% accuracy, P2) at the outlet of the bed. The air is then vented to the atmosphere through a 9.37 mm hole, which creates a back pressure in the system. The pressure gauges used in the experiment are calibrated in pound per square inch (psi), and the flow meter was calibrated in standard cubic feet per minute (SCFM). Hence, the same units were adopted throughout this study, unless a change in unit was required.