Nguyin Thi Thu ThiJy vd Dtg Tgp chi KHOA HOC & CONG NGHE 126(12); 107 111 DEVELOPMENT OF EMISSION FACTORS FOR QUENCHING PROCESS TO EMISSIONS INVENTORY Nguyen Thi Thu Thuy*, Nguyen Thi Hanh, Nguyen Thi[.]
Trang 1D E V E L O P M E N T O F EMISSION F A C T O R S F O R Q U E N C H I N G P R O C E S S
T O E M I S S I O N S I N V E N T O R Y
Nguyen Thi Thu Thuy*, Nguyen Thi Hanh, Nguyen Thi Thu Phuong
College of Technology - TNU
SUMMARY
At the coking plant, there are many manufacturing processes which generate air pollutants and impact on the environment, including coke quenching Inventory of emission of coke production process make significant contribution to air pollution control and environmental management In determined Samples of gaseous pollutants in the flue were collected using a stack sampler of APEC XC572-V and following USEPA methods 6, 7, 10 Based on monitoring and the process information, total emissions and emission factors of these pollutants for this process were determined Based on burning fiiel, the emission factors of CO, SO2, and NO2 in the experiment were 0.029 mg/kg; 0.012 mg/kg; and 0.004 mg/kg, respectively Alternatively, based on coke mg/kg; and 0.005 mg/kg, correspondingly The results obtained from the research can be used for industrial emission inventories and air quality management in Viet Nam
KeywordsiAlr polluani, coke quenching, emission, emission fiiclor, inventory
INTRODUCTION
An emission factor is a representative value
that attempts to relate the quantity of a
pollutant released to the atmosphere with an
activity associated with the release of that
pollutant Emission inventories are
fundamental tools for air quality management
They are used for identifying major
contributors of atmospheric pollutants,
developing emission control strategies,
determining applicability of permitting
programs, and other related applications [4]
Metallurgical coke is produced by the
destructive distillation of coal in coke ovens
Prepared coal is heated in an oxygen-fi-ee
ahnosphere (-cooked-) at 950-I050°C until
most volatile components in the coal are
removed The material remaining is a carbon
mass called coke [5] At the coke plant, there
are many manufacturing processes which
generate air pollutants to impact on the
environment, including coke quenching
However, data on emission factors for coke
production is scarce includmg Viet Nam This
' Email: Tkuynguyenktml@tnuudu v
Study; therefore, aims to develop the emission factors of coke production in Vietnamese conditions This paper presents preliminary results on the emission factors
of coke quenching process for Thai Nguyen Iron and Steel Joint Stock Company
MATERIALS AND METHODS Process description This study was conducted at Coking Factory
of Thai Nguyen Iron and Steel Joint Stock Company There are three main houses in this company including coking house, chemistry house, and steel rolling house,
From raw coal storage, coal is put into bunker and is pushed to mixing bins and, at which, the coal is usually a blend of two or more kinds of coal Then, it is heated in sealed chamber without air with the temperature inside oven reaching from 950''C to 1050°C in
20 minutes At the end of process, the coke is pushed through a coke guide into a special railroad car called a quench car The quench car carries the coke to a quench tower where
it is deluged with water to prevent the coke from burning after exposure to air When
Trang 2coke is cold, it is crushed, screened and gone
to coke storage
Emission and cootrol
There are many emission points in coke
production such as door emissions,
combustion stack emissions, pushing
emissions, quenching emissions etc which
were shown in Figure 1 In this research,
quenching emissions were chosen to study
The flue gas of coke quenching, after being
treated by a spray tower scrubber (made of
stainless steel, 4m high) and a tray tower
absorber (made of stainless steel, 6.2 m high),
is emitted into the atmosphere at the height of
33m via an exhaust pipe on the top of the
absorber This exhaust pipe is 2m high and
lm in diameter There is a monitoring port
located at 1.5 m from the open end of this
exhaust pine This monitoring port was used
for the stu
Sampling and analytical methods
Samples were collected at the same time of a
batch of coke quenching production on March
(CTI), May (CT2), and August (CT3) in
2014, based on US EPA methods 6, 7, 10 for
SO2, NOx, CO, respectively Then, samples
were preserved and analyzed in laboratory
following TCVN 7242:2000, TCVN
6750:2005, TCVN 7172:2002 for CO, SO2,
NO2, respectively
Calculation method
Emission: The total emission of eacli pollutant is calculated by the following formula:
Total emission = C|.L.t (mg) (1) Where, C, is the concentration of each pollutant (mg/m^), L is the flow of flue gas (m^/h) and t (h) is the monitoring time Emission factors: The emission factors of each pollutant are calculated by the following formula:
t-fiieKi-producl Where, EF, is the emission factor of each pollutant, E, is the emission of each pollutant and Efiiei/Eproduct are the amount of fliel and product, respectively
Emission rates: The emission rates of each pollutant are calculated by the following formula:
Where, ER, is the emission rate of each pollutant, E, is the emission of each pollutant and t (h) is the monitoring time
Figure 1: Some major emission points in coke production
Trang 3Figure 2 Diagram of the flue gas treatment system and monitoring port
RESULTS AND DISCUSSIONS
Concentration of air pollutants
Average concentrations of the pollutants in the flue gas of coke quenching process were shown in Table 1 As can be seen from Table 1, while the concentration of SO2, NO, were not so high, concentration of CO was extremely high and exceeded the respectivestandardof QCVN19:2009/BTNMT[2] In coke oven, coal is heated in sealed chamber without air, the insufficient led to complete combustion Therefore, the concentration of CO is so high
Table I: Summary Information of the flue gas of coke quenching production
Sample
CTI
CT2
Temperature
T C O
84-85
84-85
Average
Flow rate (Nm'/h)
50000
50000
CO (rag/Nm') 1200.81 1210.84 1206.6±5.2
Concentration SOjCmg/Nra') 225.43 226.74 226.96±1.7
NO, (mg/Nm') 86.83 106.25 96.47±9.7 Emission factors
Based on the data of monitoring, total emissions were calculated following (1) with sampling time was twenty minutes
Then, emission factors of air pollutants were calculated following (2) and results were shown in Table 2
Table 2: Emission factors of coke quenching production
Average
amount of
coal/batch
(kg)
7900
Average
amount of
coke/batch
(kg)
6500
CO Coal Coke based based 0.029 0.035
Emission factor(mg/kg)
SO, Coal Coke based based 0.012 0.015
NO, Coal Coke based based 0.004 0.005 Data on emission factors in this study were compared with other studies Data on the emission factors of gaseous pollutants available in the open literature are mainly for the whole coking process Data for specific steps of this process are very scarce Data on emission factors in the step of coke furnace pushing and controlled door leak emission can be considered to be the same range with those of coke quenching [4] The results in this study were also compared with the study of Thuy et al [3]
As can be seen in Figure 3, the emission factors of NO and SO2 in this study were relatively similar with those of Thuy's study However, there are some differences between the results in this study and those of Thuy's study although two experiments were conducted in the same place
Trang 40.06
0.04 ' J 1
-CO S02
DThis study
NOx
• 14]
Figure 3: Comparison of emission factors
In Thuy's study, they used combustion gas
analyzer to measure directly the concentration
of pollutants Type of function was chosen on
the least standard error using SPSS version
16.0 The total emission of a pollutant was the
obtained by intergrading the function of this
pollutant for
the whole time of a batch Different study
method leads to the differences of these
results can be easily under stood
Table 3: Emission rates ofeoke quenehing
production
Pollutants
NO,
SO,
CO
Emission
rates (mg/h)
88.76
290.51
Annual Emission (ton/year) 0.73 2.18
Emission rates and annual emission
Emission factor is a good basis to compare
pollutant emission from emission from
combustion of different fuels Emission rates
are usually expressed as the weight of
pollutant emitted divided by duration of the
activity emitting die pollutant The emission
rates are calculated following (3) Based on data
on emission factors can be inventoried total annual attnosphere of CO, SO2, NO, for coke quenching and result are shown in Table 3 Among atmospheric pollutants, total annual emission of CO is the highest It is the major agent to impact on the health of workers and air pollution in this area
CONCLUSIONS
In this study, emission factors including CO, SO2, NOjof coal-based and coke-based were determined in coke quenching processfor Thai Nguyen Iron and Steel Joint Stock Company The emission rates and the total annual emission of CO, SO2, NO, were also determined Emission factors in this study are
in the same range with other studies, and the results make confribution to Viet Nam database of emission factors for coke product
REFERENCES
1 E.HasSnen, L.Aunela-Tapola,V Kinnunen, et bulk and trace elements from oil shale fueled power plants, The Science of the Total Environment 1997
2 MONRE QCVN 19:2009/BTNMT; National Technical Regulation on Indusfrial Emission of Inorganic Substances and Dusts.Hanoi,2009
3 Nguyen Thi Thu Thuy, Nghiem Tmng Dung ."Determination of emission factors for coke
quenching" Journal of science & Technology
Technical untversities No 87, 2012, pages 64-46
4 US Environmental Protection Agency Procedures for Preparing Emission Factor Documents USA, 1997
5 US Environmental Protection Agency
"Emissions Factors Documentation for AP 42,
Trang 5TOM TAT
XAY DyNG HE SO PHAT THAI CHO QUA TRINH DAP COC PHUC VU CONG TAC KEEM KE KHI THAI
Nguyin Thi Thu Thuy*, Nguyen Thj H a n h , Nguyin Thj Thu Phirong
Trudng Dgi hoc Ky Thuat Cong Nghiep - DH Thdi Nguyen
Tai nha m i y coc hoa, c6 nhieu qua trinh san xuat sinh ra khi thai gSy anh huong ldn dSn moi truong khong khi, trong d6 c6 qua trinh dap coc Kigm ke phit thai ctia qua trinh sin ?< udt c6c d6ng gdp vai tr6 vo ciing quan trgng trong kiem so^t 6 nhilm khong khi v i quan ly moi •ni6ng
Trong nghign cu-u nay, nong dp c^c chdt 6 nhilm CO2, SO3, NO^ trong q u i trinh dap coc d t g c xac dinh Mau khi thai dugc thu thgp bang mdy do APEC XC572-V vk theo phucmg phap US EPA 6,
7, 10 Dua v i o dil li6u quan trSc va thong tin ve qua trinh coc hda, t6ng iuong phat thai va h6 s6 phdt thai ciia nhimg chat 6 nhiem dugc xdc djnh Tinh todn dya tren lui^ng nhi§n ligu, hS s6 phat thai CO, SO2, vd NO2 trong thi nghigm ISn lupt la 0,029 mg/kg; 0,012 mg/kg; va 0,004 mg/kg
la 0,035 mg/kg; 0,015 mg/kg; vd 0,005 mg/kg Cac kgt qua thu dugc tir nghign ciiu co thi dugc sir dung cho kilm kg khi thdi cong nghiep vd quan ly chdt lugng khong khi tai Viet Nam
T u kh6a: khi thdi, ddp eoc, phdt thdi, he sdphdt thdi kiim ke
Ngdy nhdn bdi' 15/9/2014; Ngdy phdn bien:09/10/2014; Ngdy duyet ddng: 25/10/2014
Phan biin khoa hoc: TS Mgc Duy Huy - Trudng Dai hoe Ky thudt Cdng nghiep - DHTN
' Email: Thuynguyenktmt@tnut.edu vn