Decomposition of odor substances by a packed-bed ...
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2400 2200 2000 1800 1600 1400 1200 1000 concentration [ppm] 45 40 35 30 25 20 15 10 5 0 time [min] butyraldehyde isobutyraldehyde valeraldehyde ozone harf-life 100 80 60 40 20 0 decomposition [%] 45 40 35 30 25 20 15 10 5 0 time [min] butyraldehyde isobutyraldehyde valeraldehyde 100 80 60 40 20 0 decomposition [%] 120 100 80 60 40 20 0 time [min] open : w/o water filled : w/ water 1 L/min 5 L/min 10 L/min 100 80 60 40 20 0 decomposition [%] 120 100 80 60 40 20 0 time [min] 1 L/min 5 L/min 10 L/min open : w/o water filled : w/ water Decomposition of odor substances by a packed - bed dielectric barrier discharge Kento Masuda 1 , Kenta Chida 2 , Kohki Satoh 1,3 and Hidenori Itoh 1 1 Division of Information and Electronic Engineering, Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan 2 Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585, Japan 3 Center of Environmental Science and Disaster Mitigation for Advanced Research, Muroran Institute of Technology, Muroran, 050-8585, Japan Email : [email protected] 1. Introduction 2. Experimental apparatus and conditions 3. Results and discussion 4. Conclusion Odor substances emitted from factories, garbage plants, sewage farms etc. give off very strong smell, even though the concentrations of the substance are very low. Discharge reactor A packed-bed dielectric barrier discharge reactor consists of a glass tube, in which glass or TiO 2 balls of 3.0 mm in diameter are packed, an inner stainless-steel rod electrode of 2.0 mm in diameter and an outer mesh electrode. Gas conditions The mixture ratio of a background gas is N 2 /O 2 = 80/20 %, and odor substances are added to the background gas to make an artificial odor gas in a gas holder. The initial concentrations of CH 3 (CH 2 ) 2 CHO, (CH 3 ) 2 CHCHO, and CH 3 (CH 2 ) 3 CHO are 200 ppm, that of CH 3 SH is 4 ppm. The artificial odor gas is sealed in the gas holder at 1013 hPa, and circulated to the discharge reactor at constant gas flow rates of 1.0, 5.0 or 10.0 L/min. Analyses of gaseous by-products Off-gas from the gas holder is analyzed by a Fourier Transform Infrared Spectrophotometer (JASCO, FT/IR-4200). Applied voltage An AC high voltage of 12 KV generated by a neon-sign transformer (KODERA, CR-N16) is applied to the rod electrode to generate a PB- DBD. Recently, deodorization methods using discharge plasma have attracted attention. (1) Analysis of the by - products (4) Decomposition of odor substances by ozone (3) Discharge input power and decomposition efficiency Background [1] J. S. Chang : OYO BUTSURI , 69 , No.3, 268 (2000) [2] Ogata et al. : Deodorization and air cleaning techniques with radical reaction, active species and discharge plasma, and effect and applicat ion s to human by negative ion, NTS, 126 (2002) Decomposition characteristics of mixed odor substances in a packed-bed dielectric barrier discharge are investigated. CO 2 , CO, HNO 3 and HCOOH are produced from the mixed odor substances, and O 3 and N 2 O are produced from background gas. The decomposition rate tend to be higher with increase of the gas flow rate. Using glass balls, flowing the gas with the rate of 10.0 L/min and keeping humidity in the gas holder in 0 % RH are probably suitable for the deodorization. The odor substances are decomposed by ozone. Discharge reactor Packed - bed DBD Gas inlet Gas outlet Mesh electrode Rod electrode Gas Holder A gas holder is an acrylic cylinder of 235 mm in diameter, 1030 mm in height and its volume is 40 L. H O C S To investigate the decomposition characteristics of mixed odor substances in a packed - bed dielectric barrier discharge. Objective CH 3 (CH 2 ) 2 CHO Butyraldehyde Odor threshold : 0.03 ppb (CH 3 ) 2 CHCHO Isobutyraldehyde Odor threshold : 0.09 ppb CH 3 (CH 2 ) 3 CHO Valeraldehyde Odor threshold : 0.07 ppb CH 3 SH Methyl mercaptan Odor threshold : 0.01 ppb ……. Recent works for the deodorization using the discharge plasma investigate the decomposition rate of benzene (C 6 H 6 ) in a packed-bed dielectric barrier discharge (PB-DBD) with different packed materials, and the influence of the dielectric constant on the decomposition rate. Ogata et al. [2] However, the decomposition characteristics of mixed odor substances have been done in few papers. The plasma deodorization has a wider concentration range than those of conventional methods [1] . Infrared absorbance spectra (packed material : glass balls, gas flow rate : 5.0 L/min, relative humidity : 0 %) 2.5 2.0 1.5 1.0 0.5 0.0 absorbance [a.u.] 3500 3000 2500 2000 1500 1000 500 wavenumber [cm -1 ] 2.5 2.0 1.5 1.0 0.5 0.0 without discharge with discharge CH 3 (CH 2 ) 2 CHO (CH 3 ) 2 CHCHO CH 3 (CH 2 ) 3 CHO CO 2 N 2 O O 3 CO HNO 3 HNO 3 HCOOH N 2 O 5 (2) Decomposition rate of the odor substances Packed material Humidity [%] Flow Rate [L/min] Time to be removed [min] ① ② Decomposition efficiency [g/kWh] Provided power [W] Provided electric energy [Wh] Input power [W] Input electric energy [Wh] ① ② glass Balls 0 1.0 90 4.0 5.8 3.01 4.32 14.2 19.1 5.0 65 4.0 4.4 3.10 3.29 18.6 25.1 10.0 55 4.0 3.8 3.21 2.73 21.7 30.2 60 ~ 70 1.0 120 4.2 8.2 3.14 6.00 10.8 13.7 5.0 80 4.2 5.5 3.12 3.91 14.9 21.1 10.0 65 4.0 4.1 3.21 2.85 19.9 28.9 TiO 2 balls 0 1.0 100 5.6 8.9 4.55 7.22 9.3 11.4 5.0 75 5.6 6.3 4.78 4.88 13.2 16.9 10.0 55 5.6 5.0 4.66 3.80 16.7 21.7 60 ~ 70 1.0 120 5.4 10.8 4.38 8.50 6.7 8.1 5.0 105 5.6 9.5 4.33 7.40 9.7 11.7 10.0 70 5.6 6.4 4.60 4.77 13.0 17.3 CO 2 , CO, HNO 3 and HCOOH are produced from the odor substances in the discharge. It is found that CO 2 and CO are major by-products, and that HNO 3 and HCOOH are minor by-products. Glass balls TiO 2 balls It is found that ozone decompose the odor substances. The concentration of ozone tend to decrease, because ozone is used for the decomposition. The decomposition rates tend to be higher with the increase of the discharge time and the flow rates. The decomposition rates tend to be lower with water addition and using TiO 2 balls. ○ butyraldehyde □ isobutyraldehyde △ valeraldehyde ○ butyraldehyde □ isobutyraldehyde △ valeraldehyde Flow rate [L/min] Time [min] Concentration of ozone [ppm] 1 2 63.7 5 1 24.6 10 1 22.2 (i) Decomposition of butyraldehyde, isobutyraldehyde and valeraldehyde (ii) Decomposition of methyl mercaptan Methyl mercaptan is decomposed even though all gases is not circulated. Ozone generated in the reactor is flowed to the gas holder, and decompose methyl mercaptan. ① ② decomposition efficiency [g/kWh] = decomposed concentrations [ppm] × 40 [L] × 278 [g/mol] 22.4 [L] × 10 6 × electric energy [kWh] The mass of each substances [g/mol] Methyl mercaptan : 48, Butyraldehyde : 72, Isobutyraldehyde : 72, Valeraldehydye : 86 Decomposition rate Concentration of ozone The decomposition efficiency tends to be higher at the gas flow rate of 10.0 L/min without water addition when the glass balls are used as the packed materials. The Packed material is glass balls. The gas flow rate is 10 L/min. Relative humidity in the gas holder is 0 %. Optimum condition for deodorization
Transcript of Decomposition of odor substances by a packed-bed ...
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Decomposition of odor substances by a packed-bed dielectric barrier discharge
Kento Masuda1, Kenta Chida2, Kohki Satoh1,3 and Hidenori Itoh1
1Division of Information and Electronic Engineering, Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan2Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585, Japan
3Center of Environmental Science and Disaster Mitigation for Advanced Research, Muroran Institute of Technology, Muroran, 050-8585, Japan
Email : [email protected]
1. Introduction 2. Experimental apparatus and conditions
3. Results and discussion
4. Conclusion
Odor substances emitted from factories, garbage plants, sewage farms etc. give off very strong smell, even
though the concentrations of the substance are very low.
Discharge reactor
A packed-bed dielectric barrier discharge reactor consists of a glass tube, in which glass or TiO2
balls of 3.0 mm in diameter are packed, an inner stainless-steel rod electrode of 2.0 mm in diameter and an outer mesh electrode.
Gas conditions
The mixture ratio of a background gas is N2/O2 = 80/20 %, and odor substances are added to the background gas to make an artificial odor gas in a gas holder.
The initial concentrations of CH3(CH2)2CHO, (CH3)2CHCHO, and CH3(CH2)3CHO are 200 ppm, that of CH3SH is 4 ppm.
The artificial odor gas is sealed in the gas holder at 1013 hPa, and circulated to the discharge reactor at constant gas flow rates of 1.0, 5.0 or 10.0 L/min.
Analyses of gaseous by-products Off-gas from the gas holder is analyzed by a Fourier Transform Infrared Spectrophotometer (JASCO, FT/IR-4200).
Applied voltage
An AC high voltage of 12 KV generated by a
neon-sign transformer (KODERA, CR-N16) is
applied to the rod electrode to generate a PB-
DBD.
Recently, deodorization methods using discharge plasma have attracted attention.
(1) Analysis of the by-products
(4) Decomposition of odor substances by ozone
(3) Discharge input power and decomposition efficiency
Background
[1] J. S. Chang : OYO BUTSURI, 69, No.3, 268 (2000) [2] Ogata et al.: Deodorization and air cleaning techniques with radical reaction, active species and discharge plasma, and effect and applications to human by negative ion, NTS, 126 (2002)
Decomposition characteristics of mixed odor substances in a packed-bed dielectric barrier discharge are investigated.
CO2, CO, HNO3 and HCOOH are produced from the mixed odor substances, and O3 and N2O are produced from background gas.
The decomposition rate tend to be higher with increase of the gas flow rate.
Using glass balls, flowing the gas with the rate of 10.0 L/min and keeping humidity in the gas holder in 0 % RH are probably suitable for the deodorization.
The odor substances are decomposed by ozone.
Discharge reactor
Packed-bed DBD
Gas inlet Gas outletMesh electrode
Rod electrode
Gas Holder
A gas holder is an acrylic cylinder of 235 mm in diameter, 1030 mm in height and its volume is 40 L.
H OCS
To investigate the decomposition characteristics of mixed odor substances in a packed-
bed dielectric barrier discharge.
Objective
CH3(CH2)2CHO
Butyraldehyde
Odor threshold : 0.03 ppb
(CH3)2CHCHO
Isobutyraldehyde
Odor threshold : 0.09 ppb
CH3(CH2)3CHO
Valeraldehyde
Odor threshold : 0.07 ppb
CH3SH
Methyl mercaptan
Odor threshold : 0.01 ppb
…….Recent works for the deodorization using the discharge plasma
investigate the decomposition rate of benzene (C6H6) in a packed-bed dielectric barrier
discharge (PB-DBD) with different packed materials, and the influence of the dielectric
constant on the decomposition rate.
Ogata et al.[2]
However, the decomposition characteristics of mixed odor substances have been done in few papers.
The plasma deodorization has a wider concentration range than those of conventional methods[1].
Infrared absorbance spectra(packed material : glass balls, gas flow rate : 5.0 L/min, relative humidity : 0 %)
2.5
2.0
1.5
1.0
0.5
0.0
abso
rban
ce [
a.u
.]
3500 3000 2500 2000 1500 1000 500
wavenumber [cm-1
]
2.5
2.0
1.5
1.0
0.5
0.0
without discharge
with discharge
CH3(CH2)2CHO
(CH3)2CHCHO
CH3(CH2)3CHO
CO2
N2O
O3
COHNO3HNO3
HCOOH
N2O5
(2) Decomposition rate of the odor substances
Packed
material
Humidity
[%]
Flow
Rate
[L/min]
Time
to be
removed
[min]
① ② Decomposition
efficiency
[g/kWh]
Provided
power
[W]
Provided
electric energy
[Wh]
Input
power
[W]
Input
electric energy
[Wh] ① ②
glass
Balls
0
1.0 90 4.0 5.8 3.01 4.32 14.2 19.1
5.0 65 4.0 4.4 3.10 3.29 18.6 25.1
10.0 55 4.0 3.8 3.21 2.73 21.7 30.2
60 ~ 70
1.0 120 4.2 8.2 3.14 6.00 10.8 13.7
5.0 80 4.2 5.5 3.12 3.91 14.9 21.1
10.0 65 4.0 4.1 3.21 2.85 19.9 28.9
TiO2
balls
0
1.0 100 5.6 8.9 4.55 7.22 9.3 11.4
5.0 75 5.6 6.3 4.78 4.88 13.2 16.9
10.0 55 5.6 5.0 4.66 3.80 16.7 21.7
60 ~ 70
1.0 120 5.4 10.8 4.38 8.50 6.7 8.1
5.0 105 5.6 9.5 4.33 7.40 9.7 11.7
10.0 70 5.6 6.4 4.60 4.77 13.0 17.3 CO2, CO, HNO3 and HCOOH are produced from the odor substances in the discharge.
It is found that CO2 and CO are major by-products, and that HNO3 and HCOOH are minor by-products.
Glass balls TiO2 balls
It is found that ozone decompose the odor substances.
The concentration of ozone tend to decrease, because ozone is used for the decomposition.
The decomposition rates tend to be higher with the increase of the discharge time and the flow rates.
The decomposition rates tend to be lower with water addition and using TiO2 balls.
○ butyraldehyde
□ isobutyraldehyde
△ valeraldehyde
○ butyraldehyde
□ isobutyraldehyde
△ valeraldehyde
Flow rate
[L/min]
Time
[min]
Concentration of ozone
[ppm]
1 2 63.7
5 1 24.6
10 1 22.2
(i) Decomposition of butyraldehyde, isobutyraldehyde and valeraldehyde
(ii) Decomposition of methyl mercaptan
Methyl mercaptan is decomposed even though all gases
is not circulated.
Ozone generated in the reactor is flowed to the gas
holder, and decompose methyl mercaptan.
①
②
decomposition efficiency [g/kWh] =decomposed concentrations [ppm]× 40 [L]× 278 [g/mol]
22.4 [L]× 106× electric energy [kWh]
The mass of each substances [g/mol]
Methyl mercaptan : 48, Butyraldehyde : 72, Isobutyraldehyde : 72, Valeraldehydye : 86
Decomposition rate Concentration of ozone
The decomposition efficiency tends to be higher at the gas flow rate of 10.0 L/min without
water addition when the glass balls are used as the packed materials.
The Packed material is glass balls.
The gas flow rate is 10 L/min.
Relative humidity in the gas holder is 0 %.
Optimum condition for deodorization
