Absorption of Benzene Vapor in Packed Tower

During treatment of groundwater, radon is often coincidentally removed by processes typically used to remove volatile organic compounds (VOCs)-for example, processes such as liquid-phase granular activated carbon (LGAC) adsorption and air stripping with vapor-phase carbon (VGAC). The removal of radon from drinking water is a positive benefit for the water user; however, the accumulation of radon on activated carbon may cause radiologic hazards for the water treatment plant operators and the spent carbon may be considered a low-level radioactive waste. To date, most literature on radon removal by water treatment processes was based on bench- or residential-scale systems. This paper addresses the impact of radon on municipal and industrial-scale applications. Available data have been used todevelop graphical methods of estimating the radioactivity exposure rates to facility operators and determine the fate of spent carbon. This paper will allow the reader to determine the potential for impact of radon on the system design and operation as follows.Estimate the percent removal of radon from water by LGAC adsorbers and packed tower air strippers. Also, a method to estimate the percent removal of radon by VGAC used for air stripper off-gas will be provided.Estimate if your local radon levels are such that the safety guidelines, suggested by USEPA (United States Environmental Protection Agency), of 25 mR/yr (0.1 mR/day) for radioactivity exposure may or may not be exceeded.Estimate the disposal requirements of the waste carbon for LGAC systems and VGAC for air stripper “Off-Gas” systems. Options for dealing with high radon levels are presented.

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Preparation and Gas Sensing Properties of PANI/SnO2 Hybrid Material

Polymers ◽

10.3390/polym13091360 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1360

Author(s):

Qiaohua Feng ◽

Huanhuan Zhang ◽

Yunbo Shi ◽

Xiaoyu Yu ◽

Guangdong Lan

Keyword(s):

Hybrid Material ◽

Room Temperature ◽

Tin Dioxide ◽

Gas Adsorption ◽

Gas Sensing ◽

Oxidative Polymerization ◽

Environmental Pollutants ◽

Decomposition Temperature ◽

Benzene Vapor ◽

Thermo Gravimetric Analyzer

A sensor operating at room temperature has low power consumption and is beneficial for the detection of environmental pollutants such as ammonia and benzene vapor. In this study, polyaniline (PANI) is made from aniline under acidic conditions by chemical oxidative polymerization and doped with tin dioxide (SnO2) at a specific percentage. The PANI/SnO2 hybrid material obtained is then ground at room temperature. The results of scanning electron microscopy show that the prepared powder comprises nanoscale particles and has good dispersibility, which is conducive to gas adsorption. The thermal decomposition temperature of the powder and its stability are measured using a differential thermo gravimetric analyzer. At 20 °C, the ammonia gas and benzene vapor gas sensing of the PANI/SnO2 hybrid material was tested at concentrations of between 1 and 7 ppm of ammonia and between 0.4 and 90 ppm of benzene vapor. The tests show that the response sensitivities to ammonia and benzene vapor are essentially linear. The sensing mechanisms of the PANI/SnO2 hybrid material to ammonia and benzene vapors were analyzed. The results demonstrate that doped SnO2 significantly affects the sensitivity, response time, and recovery time of the PANI material.

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Packed Tower Air Stripping – An Economical Alternative for Meeting California's Stringent THM Limits

Proceedings of the Water Environment Federation ◽

10.2175/193864711802713180 ◽

2011 ◽

Vol 2011 (15) ◽

pp. 1869-1889

Author(s):

Katy Rogers ◽

Michael Britten ◽

Michael Hartlaub ◽

Peter von Bucher

Keyword(s):

Air Stripping ◽

Packed Tower ◽

Economical Alternative

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Gas Cooling and Humidification: Design of Packed Towers from Small-Scale Tests

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1950_163_010_02 ◽

1950 ◽

Vol 163 (1) ◽

pp. 41-53 ◽

Cited By ~ 11

Author(s):

W. F. Carey ◽

G. J. Williamson

Keyword(s):

Operating Conditions ◽

Total Heat ◽

Small Scale ◽

Water Cooling ◽

Packed Tower ◽

Simple Method ◽

Worked Example ◽

Gas Cooling ◽

Heat Method ◽

Working Out

On plants in which gases are processed, the gases are often brought into direct contact with water—usually in packed towers. The purpose may be to cool a hot gas, to increase the humidity of a gas, or, in the well-known special case of water-cooling towers, to cool water by contact with atmospheric air. These processes involve simultaneous transfers of sensible heat and water vapour, and existing methods of analysis are complex and laborious, except for the cooling of water, for which Merkel's total-heat method has long been available. Merkel's approximate solution offers the engineer a simple method of working out, for any operating conditions, the amount of heat transferred and the “driving force” available for transferring it. The present paper generalizes the total-heat method and, with a permissible sacrifice in accuracy, preserves the essential simplicity of the water-cooling treatment for gas-cooling and humidification processes. To complete the design of a packed tower, a knowledge is required of the characteristics of the packing. Information obtained in small towers is given for a number of packings, and a worked example shows how to apply the method of treatment, and the packing data presented, to the design of a large plant tower.

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Trickle/pulse flow regime transition in downflow packed tower involving foaming liquids

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq111201011s ◽

2012 ◽

Vol 18 (3) ◽

pp. 349-359

Author(s):

Vijay Sodhi

Keyword(s):

Surface Tension ◽

Liquid Flow ◽

Liquid Surface ◽

Regime Transition ◽

Pulse Flow ◽

Packed Tower ◽

Flow Rates ◽

Transition Boundary ◽

Liquid Surface Tension ◽

Pulsing Flow

The most of past studies in foaming trickle bed reactors aimed at the improvement of efficiency and operational parameters leads to high economic advantages. Conventionally most of the industries rely on frequently used gas continuous flow (GCF) where operational output is satisfactory but not yields efficiently as in pulsing flow (PF) and foaming pulsing flow (FPF). Hydrodynamic characteristics like regime transitions are significantly influenced by foaming nature of liquid as well as gas and liquid flow rates. This study?s aim was to demonstrate experimentally the effects of liquid flow rate, gas flow rates and liquid surface tension on regime transition. These parameters were analyzed for the air-aqueous Sodium Lauryl Sulphate and air-water systems. More than 240 experiments were done to obtain the transition boundary for trickle flow (GCF) to foaming pulsing flow (PF/FPF) by use excessive foaming 15-60 ppm surfactant compositions. The trickle to pulse flow transition appeared at lower gas and liquid flow rates with decrease in liquid surface tension. All experimental data had been collected and drawn in the form of four different transitional plots which are compared and drawn by using flow coordinates proposed by different researchers. A prominent decrease in dynamic liquid saturation was observed especially during regime transitional change. The reactor two phase pressure evident a sharp rise to verify the regime transition shift from GCF to PF/FPF. Present study reveals, the regime transition boundary significantly influenced by any change in hydrodynamic as well as physiochemical properties including surface tension.

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Analysis of Heat and Mass Transfer Between a Desiccant-Air System in a Packed Tower

Journal of Solar Energy Engineering ◽

10.1115/1.3268198 ◽

1987 ◽

Vol 109 (2) ◽

pp. 89-93 ◽

Cited By ~ 59

Author(s):

P. Gandhidasan ◽

M. Rifat Ullah ◽

C. F. Kettleborough

Keyword(s):

Mass Transfer ◽

Gas Phase ◽

Heat And Mass Transfer ◽

Packing Material ◽

Mass Transfer Resistance ◽

Liquid Desiccant ◽

Governing Equations ◽

Packed Tower ◽

Transfer Resistance ◽

Steady State Model

Heat and mass transfer analysis between a desiccant-air contact system in a packed tower has been studied in application to air dehumidification employing liquid desiccant, namely calcium chloride. Ceramic 2 in. Raschig rings are used as the packing material. To predict the tower performance, a steady-state model which considers the heat and mass transfer resistances of the gas phase and the mass transfer resistance of the liquid phase is developed. The governing equations are solved on a digital computer to simulate the performance of the tower. The various parameters such as the effect of liquid concentration and temperature, air temperature and humidity and the rates of flow of air and liquid affecting the tower performance have been discussed.

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An Analysis of Packed Bed Liquid Desiccant System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.390.680 ◽

2013 ◽

Vol 390 ◽

pp. 680-684

Author(s):

Hesamoddin Salarian

Keyword(s):

Mass Transfer ◽

Volume Ratio ◽

Packed Bed ◽

Characteristic Parameter ◽

Flow Rate Ratio ◽

Liquid Desiccant ◽

Packed Tower ◽

Air Conditioning System ◽

New Type ◽

Packing Size

In this paper a new type of open absorption the liquid desiccant, air conditioning system will be introduced. The dehumidifier and regenerator play the most important role in this system.For liquid-gas contact, packed towers with low pressure drop provide good heat and mass transfer characteristics for compact designs. Thus, this analysis considers the packed tower liquid desiccant systems. The experimental data have been obtained from a built prototype of liquid desiccant system in a packed bed unit with a surface area per unit volume ratio of 125m2/m3, the liquid desiccant, viz lithium chloride. The result showed that the mean mass transfer coefficient of the packing dehumidifier was 0.02kg/m2s. Also the absorber characteristic parameter, the packing size or number of transfer units (NTU), and air-to-desiccant solution mass flow rate ratio (ASMR) are crucial parameters. These parameters affect humidity and enthalpy effectiveness and will be introduced and defined in this paper.

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