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Proceedings available at: http://www.extension.org/67656 The objective of this research was to evaluate electrolyzed water as a solution for a lab-scale spray scrubber for removing NH3 from air. A one-stage spray scrubber was fabricated to treat 50 cfm (1.42 m3/min) of introduced mixed NH3-air with an approximate NH3 concentration of 20 ppm. The mixed air was blown, countercurrent, to the 5-ft vertical scrubber body using a fan. Eight scrubber design variables were studied including contact times, nozzle types and scrubber solutions. Three contact times were 0.3, 0.6 and 0.9 s. The two narrow and standard nozzles sprinkled in a full-cone spray pattern but at different angles of 26ᴼ and 52ᴼ, respectively. The scrubber solutions variables tested were reverse osmosis (RO) water and two types of electrolyzed water (50 ppm of total chlorine) with pH = 9.0 and pH = 6.5. The 18 combinations of treatments were tested in three replications and statistically analyzed to investigate the objective. The result showed that all of the experiments were able to mitigate the NH3, but at different efficiencies. The maximum efficiency of 53% was acquired with the narrow nozzle, 0.9s contact time and electrolyzed water with pH = 6.5. Therefore, it was concluded that increasing the contact time, decreasing the pH of electrolyzed water and using the narrow angle, higher flow rate nozzle increased the scrubber efficiency.
Citation preview
Ammonia (NHAmmonia (NH33) Mitigation ) Mitigation Using an Electrolyzed Water Using an Electrolyzed Water Spray ScrubberSpray Scrubber
Gerald Riskowski, Professor, Texas A&M University, Bio. Ag. Eng. Dept.
Saqib Mukhtar, Professor, Texas A&M University, Bio. Ag. Eng. Dept.
Ahmad Kalbasi, Researcher, Texas A&M University, Bio. Ag. Eng. Dept.
Amir M. Samani Majd, PhD Candidate, Texas A&M University, Bio. Ag. Eng. Dept.
Waste to Worth Conference, Hyatt Hotel, Denver, CO. April 1-5, 2013
Introduction
NH3 emission from AFOsAdverse effects on animal and worker healthSource of Odor and Environmental Pollution
Contribute to fine particulate matter formation
Eutrophication of water bodies
Contamination of groundwater
Constituent of nitrous oxide, a potent greenhouse gas
NH3 emission into the atmosphere results in a loss of nitrogen, an essential plant nutrient.
Introduction
U.S.EPA regulation
- Environmental Planning and Community Right-to-Know Act (EPCRA)
-NH3 and H2S emissions exceeding 45.4 kg (100 lb) in any 24 hour time period are
considered a “reportable Quantity.”
IntroductionAbatement Technologies
Chemical amendments Hollow fiber mitigation technologies Bio-filtersExhaust air scrubber Packed bed scrubbers Impingement plates scrubbers Fiber beds Cyclonic spray scrubber, Venturi scrubbers Rotating beds
Higher pressure drops and operating costs compared to spray scrubbers
Objective
To develop and evaluate a lab-scale spray scrubber that uses an electrolyzed water scrubber solution.
Materials and MethodsThe main set-upThe main set-up
A one-stage spray scrubber
5-ft vertical scrubber body
Materials and MethodsThe main set-upThe main set-up
A fan blew 50 cfm of mixed NH3& air into the scrubber stream
Approximate NH3
concentration in simulated exhaust air was 20 ppm
Materials and MethodsTwo Types of Nozzles Used for Nozzles Used for Scrubbing Exhaust AirScrubbing Exhaust Air
Narrow-Angle Full Cone Nozzle
Standard Type Full Cone Nozzle
Materials and MethodsThe main set-upThe main set-up
Two types of nozzles: A Narrow-Angle Full Cone Nozzle A Standard Type Full Cone Nozzle
Nozzle Narrow-angle Standard Type
Spray pattern Full cone Full cone
Spray angle 26o 45o
Height of spray 30 cm (12”) 15 cm (6”)Droplet size 700-900 µm 200-300 µm
Pressure 190-200 kPa (27.6-29 psi)
190-200 kPa (27.6-29 psi)
Scrubbing solutionflow rate
5.2 L/min (~1.38 gal/min)
0.95 L/min(~0.252 gal/min)
Exhaust Air
Exhaust Air
Manometer
Air Nozzle
Drainage
Valve
Flowmeter
Pressure Gage P
F
Scrubbing Solution
Contact chamber
Pump
nozzle
Spray cone
F
P
Air Fan
NH
3 C
ylin
der
P
F Air duct
NH3 Analyzer
Preheating System
2
1
Centrifugal fan
NH3
diffuser
NH3
cylinder
NH3
flowmeter
Air duct
Manometer
Air nozzle
Contact chamber
Spray nozzle
Production of Electrolyzed waterProduction of Electrolyzed waterMembrane less Electrolyzed water Electrolyzing regular NaCl solution
In an EW solution, the most effective form of chlorine compounds include hypochlorous acid (HOCl) and hypochlorite ion (OCL-)
HOCl OCl- + H+
Materials and MethodsExperimentsExperiments
Eight Variables: 54 experiments: 18 scenarios in three
replications- Contact times: 0.3, 0.6 and 0.9
second- Nozzle types: Narrow and Standard- Scrubber solutions: Reverse osmosis
(RO) water, two types of electrolyzed water (50 ppm of total chlorine) with pH = 9.0 and pH = 6.5.
Materials and MethodsMeasurementsMeasurements
TEI model 17C chemiluminescence NH3 analyzer
Ion Selective Electrode NH3 probe & pH probe
Results and Discussion:
Treatment #
Treatment VariablesEfficiency
(%)*
Nozzle type Scrubbing solutioncontact time
(s)
1
Narrow-angle
EW, pH 6.5
0.3 37.9 (1.6)
2 0.6 51.9 (3.8)
3 0.9 56.0 (2.7)4
RO
0.3 34.7 (5.5)5 0.6 43.9 (3.6)
6 0.9 49.5 (5.6)
7EW, pH 9.0
0.3 39.0 (0.8)8 0.6 47.1(2.0)9 0.9 51.3(3.6)
Results and Discussion:
Treatment #
Treatment VariablesEfficiency
(%)*
Nozzle typeScrubbing solution
contact time (s)
10
Standard Type
EW, pH 6.5
0.3 37.9 (0.7)
11 0.6 46.7 (3.3)
12 0.9 43.9 (4.4)
13
RO
0.3 32.1 (2.5)
14 0.6 36.7 (4.8)
15 0.9 39.3 (2.8)
16
EW, pH 9.0
0.3 34.2 (7.7)
17 0.6 39.9 (3.9)
18 0.9 40.6 (0.7)
Results and Discussion:
The ammonia removal efficiency of the scrubber ranged from 34% to 56%.
Increasing the contact time, decreasing the pH of electrolyzed water and narrow spray pattern mostly increased the efficiency of the scrubber.
The maximum efficiency of 56% was for: narrow nozzle, 0.9s contact time,Electrolyzed water with pH = 6.5
Conclusions
A Wet scrubber will be designed from the knowledge gained in laboratory studies will be scaled-up for Field studies
Future Plan
Acknowledgements & Questions
Funding for this study was made possible by the State of Texas Air Quality Initiative.