Dehumidification and Simultaneous Removal of Selected Pollutants from Indoor Air by a Desiccant Wheel Using a 1M Type Desiccant

1999 ◽  
Vol 121 (1) ◽  
pp. 1-13 ◽  
Author(s):  
M. Popescu ◽  
T. K. Ghosh
Keyword(s):  
Silica Gel ◽  
Flow Rate ◽  
Molecular Sieve ◽  
Fixed Bed ◽  
Aluminum Foil ◽  
Time Interval ◽  
Simultaneous Removal ◽  
Desiccant Wheel ◽  
Face Velocity ◽  
Adsorption Cycle

Solid-desiccant dehumidifiers are increasingly becoming an integral part of desiccant based air-conditioning systems because of their effective handling of latent heat loads compared to conventional vapor compression units. In these units, either a silica gel or a molecular sieve is used for dehumidification of air. Both of them have the capability to co-adsorb various chemical pollutants during dehumidification of air. However, the shape of the isotherm for water vapor on these materials is not favorable for desiccant cooling applications. A mixture (IM desiccant) containing a silica gel, a molecular sieve, and a hydrophobic molecular sieve that was coated on an aluminum foil was studied for its capability for simultaneous removal of moisture and some selected pollutants from air. Experimental data were obtained in a fixed bed adsorber that simulated the operation of a rotary desiccant wheel. Air to be dehumidified and cleaned and the hot regeneration air were cycled in a specific time interval through this bed. The shape of the water isotherm on IM desiccant was found to be in between that of silica gel and molecular sieve 13×, but its uptake capacity was significantly lower than that of either silica gel or molecular sieve. A flow rate of about 100 L/min that provided a face velocity of about 132 cm/s was used in the adsorption step. The flow rate during regeneration was about 50 L/min. The temperature of the inlet air was about 23°C and its relative humidity was varied between 20 percent and 80 percent. The concentrations of pollutants were as follows; carbon dioxide: 1050 and 2300 ppm; toluene: 32 ppm; 1,1,1-trichloroethane: 172 ppm, and formaldehyde: 0.35 ppm. A complete breakthrough of all the pollutants was observed during an adsorption cycle. However, a removal efficiency greater than 50 percent for these pollutants was observed if the adsorption cycle time was about 1 minute.

OPTIMIZATION OF PROCESS PARAMETERS OF PRESSURE-SWING ADSORPTION CYCLE IN A SILICA GEL DESICCANT DEHUMIDIFICATION SYSTEM

2017 ◽  
Vol 13 (10) ◽  
pp. 6543-6551
Author(s):  
V.Suresh Kannan ◽  
T.V. Arjunan
Keyword(s):  
Silica Gel ◽  
Flow Rate ◽  
Cycle Time ◽  
Pressure Swing Adsorption ◽  
Air Flow ◽  
Air Flow Rate ◽  
Time Ratio ◽  
Air Inlet ◽  
Pressure Swing ◽  
Adsorption Cycle

Parametric study on pressure-swing adsorption cycle desiccant dehumidification system is a continuous engineering task with the aim of analyzing its effects and attains target quality of dry air for an industrial process. An experimental setup is developed with a dehumidification tower, regeneration tower,and flow control valve.The effect of process air inlet moisture content, cycle time ratio, and regeneration air flow rate on the adsorption performance is studied to evaluate the potential of the dehumidification system suitable for drying applications. The optimal dehumidification parameters are found, and a regression equation is also developed for the process. It is concluded that, process air inlet moisture is the most influencing parameter compared to regeneration air flow rate and cycle time ratio for the silica gel desiccant dehumidification system. 

Experiment Study of Small Composite Desiccant Wheel Based on Ceramic

2012 ◽  
Vol 614-615 ◽  
pp. 665-669
Author(s):  
Chun Xia Jia
Keyword(s):  
Silica Gel ◽  
Residential Building ◽  
Experimental Results ◽  
Moisture Removal ◽  
Experiment Study ◽  
Desiccant Wheel ◽  
Rotating Speed ◽  
Removal Capacity

Small composite desiccant wheels based on ceramic are designed and developed. The experiments test the influence of the rotating speed and wheel thickness on the dehumidification performance. Furthermore the dehumidification performance of the composite desiccant wheel is compared with the silica gel wheel. The experimental results show increasing the rotating speed of the desiccant wheel can improve the moisture removal capacity. Compared with the silica gel wheel, the moisture removal amounts of the thin composite desiccant wheel are about similar with that of the thick silica gel wheel. It is further indentified that the new composite desiccant wheel can reduce the size of the dehumidifier and has more potential for residential building field.

The Effect of Boundary Layer Separation on Accuracy of Flow Measurement Using the Gibson Method

2007 ◽  
Author(s):  
F. Z. Sierra ◽  
A. Adamkowski ◽  
G. Urquiza ◽  
J. Kubiak ◽  
H. Lara ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cross Section ◽  
Flow Rate ◽  
Pressure Difference ◽  
Proper Time ◽  
Effective Cross Section ◽  
Boundary Layer Separation ◽  
Water Hammer ◽  
Time Interval ◽  
Geometry Factor

The Gibson method utilizes the effect of water hammer phenomenon (hydraulic transients) in a pipeline for flow rate determination. The method consists in measuring a static pressure difference, which occurs between two cross-sections of the pipeline as a result of a temporal change of momentum from t0 to t1. This condition is induced when the water flow in the pipeline is stopped suddenly using a cut-off device. The flow rate is determined by integrating, within a proper time interval, the measured pressure difference change caused by the water hammer (inertia effect). However, several observations demonstrate that changes of pipeline geometry like diameter change, bifurcations, or direction shift by elbows may produce an effect on the computation of the flow rate. The paper focuses on this effect. Computational simulations have shown that the boundary layer separates when the flow faces sudden changes like these mentioned to above. The separation may reduce the effective cross section area of flow modifying a geometry factor involved into the computation of the flow rate. The remainder is directed to quantify the magnitude of such a factor under the influence of pipeline geometry changes. Results of numerical computations are discussed on the basis of how cross section reductions impact on the geometry factor magnitude and consequently on the mass flow rate.

Study of Catalytic Pyrolysis of Chlorella with γ-Al2O3 Catalyst

2013 ◽  
Vol 873 ◽  
pp. 562-566 ◽  
Author(s):  
Juan Liu ◽  
Xia Li ◽  
Qing Jie Guo
Keyword(s):  
Water Content ◽  
Molecular Sieve ◽  
Catalytic Pyrolysis ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Pyrolysis Oil ◽  
Heating Value ◽  
Lower Viscosity ◽  
Bio Oil ◽  
Liquid Yield

Chlorella samples were pyrolysed in a fixed bed reactor with γ-Al2O3 or ZSM-5 molecular sieve catalyst at 600°C. Liquid oil samples was collected from pyrolysis experiments in a condenser and characterized for water content, kinematic viscosity and heating value. In the presence of catalysts , gas yield decreased and liquid yield increased when compared with non-catalytic pyrolysis at the same temperatures. Moreover, pyrolysis oil from catalytic with γ-Al2O3 runs carries lower water content and lower viscosity and higher heating value. Comparison of two catalytic products, the results were showed that γ-Al2O3 has a higher activity than that of ZSM-5 molecular sieve. The acidity distribution in these samples has been measured by t.p.d, of ammonia, the γ-Al2O3 shows a lower acidity. The γ-Al2O3 catalyst shows promise for production of high-quality bio-oil from algae via the catalytic pyrolysis.

The Theory and the Practical Validation of the Fluid Level Position in the Annulus During Lost Circulation

2021 ◽  
Author(s):  
Alexey Ruzhnikov ◽  
Edgar Echevarria
Keyword(s):  
Flow Rate ◽  
Drilling Fluid ◽  
Time Interval ◽  
Fluid Level ◽  
Drilling Tool ◽  
Lost Circulation ◽  
Hole Pressure ◽  
Bottom Hole Pressure ◽  
Bottom Hole ◽  
Carbonate Formations

Abstract Carbonate formations around the world and specifically in a Middle East are prone to have total losses while drilling. And the nature of the losses often related to the highly fractured formations of the pay zone. When such fracture(s) is crossed by the wellbore the lost circulation initiated and led to a drilling without a return to a surface. To avoid undesired well control event or wellbore instability and to maintain the constant bottom hole pressure the mud cap drilling strategy often used as a preventative measure. The mud cap can be either the continuous or based on some volume or time interval, depends on the local practices or the policy of an operator. The mud cap flow rate as well as mud cap mud weight are often based on the best practices, not supported by an engineering study. To understand the behavior of the drilling fluid level in the annulus while drilling with total losses the drilling bottom hole assembly equipped with annular pressure while drilling tool was used. As the drilling required to use the continuous mud cap, then the specific guideline was developed on measurement of the bottom hole pressure and further conversion of it to the fluid level. The study was performed across pay zone with one or several loss circulation zones identified. As the result it was confirmed that the used mud cap flow rate had minor to none effect on the fluid level position in the annulus and that the bottom hole pressure remained the same. It showed as well that different loss zones are behaving in a different way, what can be considered as a factor affecting their ability to be sealed. The obtained knowledge and the information should help to understand better the loss circulation behavior as well be an important step toward development of the product which may cure the losses in high fractured carbonate formations. The results of the study can be implemented in any other project or a field.

Zeolite/Cerium Oxide Coat-on Activated Alumina Ball for Arsenite Removal via Fixed- Bed Continuous Flow Adsorption Column

2021 ◽  
Author(s):  
Suttikorn Suwannatrai ◽  
Dickson Y. S. Yan ◽  
Pummarin Khamdahsag ◽  
Visanu Tanboonchuy
Keyword(s):  
Cerium Oxide ◽  
Flow Rate ◽  
Continuous Flow ◽  
Human Life ◽  
Fixed Bed ◽  
Point Of Zero Charge ◽  
Contaminated Water ◽  
Activated Alumina ◽  
Initial Flow ◽  
Alumina Ball

Arsenite (As(III)) has threatened human life for ages. It is a necessity to remove As(III) from the contaminated water before general use. With the improvement of adsorption, higher As(III) removal can be achieved. This study aimed to develop zeolite/cerium oxide coat-on activated alumina ball adsorbent (CeZ-ball) with the aid of PVA binder and apply it to a fixed-bed continuous flow column for As(III) adsorption. The coating percentage of CeZ-ball was studied. Cerium ions leaching from CeZ-ball were monitored throughout the 2,880-min-column run to confirm the stability of CeZ attached to an activated alumina ball. Surface area, pH point of zero charge, and structural property of CeZ-ball were characterized. An average CeZ coating of 83.3% and rare leaching of cerium proved the coating method. The models proposed by Yoon-Nelson provided the most satisfactory fit with the breakthrough curve (r2 = 0.985, MPSD = 2.547, and q0 = 3.481 mg·g–1) under experimental conditions of the flow rate of 5 mL·min–1, As(III) influent concentration of 1 mg·L–1, and CeZ-ball weight of 40 g. The half-time of breakthrough (τ) was 1,228.739 min. The effects of the key parameters, including initial adsorbent weight, initial flow rate, and initial As(III) concentration, were investigated for the performance of As(III) adsorption. Simulated from the Yoon-Nelson model, the τ increased as well as the adsorbent weight but decreased as the flow rate increased, thus impacting the As(III) concentration. With the optimal condition, the fixed-bed continuous column with CeZ-ball could be used in As(III) removal from contaminated water.

scholarly journals Sorption of Ag+ and Cu2+ by Vermiculite in a Fixed-Bed Column: Design, Process Optimization and Dynamics Investigations

2018 ◽  
Vol 8 (11) ◽  
pp. 2221 ◽  
Author(s):  
Olga Długosz ◽  
Marcin Banach
Keyword(s):  
Flow Rate ◽  
Continuous Process ◽  
Fixed Bed ◽  
Copper Ion ◽  
Cost Effective ◽  
Breakthrough Curves ◽  
Fixed Bed Column ◽  
Column System ◽  
Total Percentage ◽  
Bed Height

Vermiculite has been used for the removal of Cu 2 + and Ag + from aqueous solutions in a fixed-bed column system. The effects of initial silver and copper ion concentrations, flow rate, and bed height of the adsorbent in a fixed-bed column system were investigated. Statistical analysis confirmed that breakthrough curves depended on all three factors. The highest inlet metal cation concentration (5000 mg/dm3), the lowest bed height (3 cm) and the lowest flow rate (2 and 3 cm3/min for Ag + and Cu 2 + , respectively) were optimal for the adsorption process. The maximum total percentage of metal ions removed was 60.4% and 68.7% for Ag+ and Cu2+, respectively. Adsorption data were fitted with four fixed-bed adsorption models, namely Clark, Bohart–Adams, Yoon–Nelson and Thomas models, to predict breakthrough curves and to determine the characteristic column parameters. The adsorbent was characterized by SEM, FTIR, EDS and BET techniques. The results showed that vermiculite could be applied as a cost-effective sorbent for the removal of Cu 2 + and Ag + from wastewater in a continuous process.

Simultaneous removal of fluoride and phosphate in a continuous fixed-bed column filled with magnesia-pullulan composite

2020 ◽  
Vol 838 ◽  
pp. 155528
Author(s):  
Yuanyao Ye ◽  
Yanjie Wei ◽  
Yiya Gu ◽  
Dejun Kang ◽  
Wei Jiang ◽  
...  
Keyword(s):  
Fixed Bed ◽  
Simultaneous Removal ◽  
Fixed Bed Column

scholarly journals Evaluation of Sorbent Sampling and Analysis Procedures for Acetone in Workplace Air: Variations of Concentration and Relative Humidity

2019 ◽  
Vol 64 (1) ◽  
pp. 96-105
Author(s):  
Jhy-Charm Soo ◽  
Ryan F Lebouf ◽  
William P Chisholm ◽  
John Nelson ◽  
Jennifer Roberts ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Silica Gel ◽  
Molecular Sieve ◽  
Mass Loading ◽  
Carbon Molecular Sieve ◽  
Humidity Effect ◽  
Atmosphere System ◽  
Acetone Adsorption ◽  
Workplace Air ◽  
Carbonaceous Sorbents

Abstract This study experimentally evaluates the performance of different sorbent tubes for sampling acetone vapor in workplace air. A dynamic atmosphere system produced an acetone alone and a mixture with other analytes containing ~73, 483, and 1898 µg acetone mass loading at 25, 50, and 75% relative humidity (RH) at 25°C. Sorbent samples were analyzed in accordance with OSHA Method 69 (Carbosieve S-III) and NMAM 1501, modified to use Anasorb 747 sorbent. Both methods were modified to include the additional analytes. Additional extraction procedures with and without 1% dimethylformamide and anhydrous magnesium sulfate were included in the modified NMAM 1501 using Anasorb 747. Silica gel sorbent tubes analyzed according to NMAM 2027 were included. There were significant reductions in the recovery of acetone from both Anasorb 747 and Carbosieve S-III collected from air at 75% RH, relative to collection at 25 or 50% RH at very low loading compared with that of samples collected at mid to high loading. Silica gel provided a consistent recovery of acetone at all RHs and in the presence of other chemical interferences at 75% RH. The likely cause of mass dependence may arise from the humidity effect on acetone adsorption onto both beaded active carbon and carbon molecular sieve either in sampling or in analysis. The present study confirms not only previous observations but also adds to the literature showing carbonaceous sorbents are not well suited for sampling ketones at high humidity and low concentration.

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