Analysis of Reduction Potential of Primary Air Pollutant

Aerosol and Air Quality Research, 18: 533–541, 2018 Copyright © Taiwan Association for Aerosol Research ISSN: 1680-8584 print / 2071-1409 online doi: 10.4209/aaqr.2017.04.0139 Analysis of Reduction Potential of Primary Air Pollutant Emissions from Coking Industry in China Yan Wang1,2, Ke Cheng2*, He-Zhong Tian3, Peng Yi4, Zhi-Gang Xue4 1 Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Key Laboratory of Environmental Pollutants and Health Effects Assessment, School of Public Health, Xinxiang Medical University, Xinxiang 453003, China 2 Henan Key Laboratory for Environmental Pollution Control, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, School of Environment, Henan Normal University, Xinxiang 453007, China 3 School of Environment, Beijing Normal University, Beijing 100875, China 4 Chinese Research Academy of Environmental Sciences, Beijing 100012, China ABSTRACT

Air pollutant emissions from the coking industry in China, the world’s largest coke producer, are a major societal concern. This study employed a bottom-up emission-factor methodology to estimate the country’s coking-industry air-pollutant emissions. Total suspended particulate matter (TSP), particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM2.5), sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), carbon monoxide (CO), and methane (CH4) were considered. The emissions in 2015 were estimated to be 368.36, 23.28, 402.54, 174.43, 1325.42, 28.24, 2036.43, and 71.68 kt for TSP, PM2.5, SO2, NOx, VOCs, PAHs, CO, and CH4, respectively, with an annual average growth rate of 1.1% during the 12th five-year-plan (2011–2015). A comparative analysis was performed on emission contributions from air pollutants produced by various types of coke ovens and using various coking procedures. The objectives of the 13th five-year-plan (2016–2020) were used to predict China’s production of coke and methods of control in 2020 and to analyze the potential reduction in typical air pollutants. The results show that emissions of TSP, SO2, and NOx will be reduced by 82.9%, 94.4%, and 6.9%, respectively. Moreover, this study proposes a series of feasible control measures for air-pollutant emissions from the coking industry in China. Keywords: Coking industry; Primary air pollutants; Emission characteristics; Reduction potential. INTRODUCTION

Coke is a crucial raw material and a fuel used in blast furnace ironmaking. The rapid development of China’s steel industry has increased the status of the country’s coking industry and emphasized its role in China’s economic development (Hu et al., 2010; CAE, 2011). The world’s largest coke producer, China generated a total coke output of 447.78 Mt in 2015, which accounted for 68.6% of the world’s total output (NBSC, 2016). However, the coking industry with coal as the primary raw material is characterized by a relatively low energy utilization rate, high energy consumption per unit, complex process flows, abundant *Corresponding author.

Tel.: +86-373-3325971; Fax: +86-373-3325971 E-mail address: [email protected]

pollution–producing links, and it’s being a large source of highly polluting matters (Zhang, 2000; Li, 2009; Tian et al., 2010; Huo et al., 2012; Mu, 2013).

Therefore, the coking industry is considered a highly polluting industry. The exhaust gas pollutants generated during coking include total suspended particulate matter (TSP), particulate matter with aerodynamic diameters less than or equal to 2.5 µm (PM2.5), sulfur dioxide, nitrogen oxides, volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). The coking industry is also a substantial contributor to greenhouse gas emissions (Zhu et al., 2001; He et al., 2006; Liu et al., 2009; Mu, 2013; Ge et al., 2016; Wu et al., 2017). Long-term exposure to coke oven emissions results in inflammation of the skin and inner eyelids and lesions in the lung and stomach (Lloyd, 1971; IARC, 1984, 2002). The United States Environmental Protection Agency (US EPA) classifies coke oven emissions as Group A carcinogens and links them to lung cancer (US EPA, 1999).

Wang et al., Aerosol and Air Quality Research, 18: 533–541, 2018 534

In March 2014, China’s Ministry of Industry and Information Technology announced its latest revision of the coking industry admission conditions, which proposed restrictions for coking companies through concrete rules for the production process and equipment used and the energy consumption per unit product of coke, in addition to formulating supplementary environmental protection measures (MIIT, 2014). Data from the China Coking Industry Association (CCIA) indicated that, of the 420 companies that applied for coking company admission qualification before 2016, 367 were admitted, and these companies combined for an actual coke output of 377.66 Mt, or approximately 50.0% of the country’s total output (CCIA, 2016a). Since January 1st, 2015, a new version of the Emission Standard of Pollutants for the Coking Chemical Industry has been take effect (MEP, 2012). The part of China’s 13th five-year-plan (2016–2020) that concerns the development of the coking industry suggests that the coking industry should meet the following conditions to ensure that all companies achieve their respective emission targets (NDRC and NEA, 2016): (1) the coking industry must eliminate coking companies that fail to meet the standard output; (2) 70.0% of the output standard for those admitted into the industry access conditions.

China’s coking industry is, however, characterized by low production concentration, generally less advanced production technologies and lower management quality, abundant small enterprises loosely distributed across the nation, and a high percentage (> 80.0%) of coking companies being independent small– and medium–sized enterprises (CCIA, 2016b). For small– and medium–sized coking companies in deficit that do not use advanced technologies, meeting the standard environmental protection targets is challenging due to the high cost of energy reservation and emission reduction.

Several studies have estimated the emissions of typical air pollutants from China’s coking industry, such as PAHs, greenhouse gases, and SO2, etc. (Zhu et al., 2001; He et al., 2006; Liu et al., 2009; Mu, 2013; Ge et al., 2016; Wu et al., 2017). However, studies analyzing the emission characteristics of the coking industry have been mainly performed for the steel industry (Wu et al., 2015a). Coking companies serving as auxiliary enterprises in the steel industry only account for 13.3% of the total number of coking companies in China, implying that few studies have collected and analyzed data of coking–industry–only companies (CCIA, 2016c).

Presently, coke used in metallurgical industries (including the steel industry) is mainly produced through the coking of coal. The ability to reduce emission for air pollutants is a crucial factor for overall pollution prevention and control in the coking industry. Reducing and better monitoring the emissions of air pollutants from coke ovens is required to improve ambient air quality, maintain a sufficient level of coke production, and meet ongoing new regulations. Therefore, the emissions of typical primary air pollutants from the coking industry in China were estimated in this study. The air pollutants considered included TSP, PM2.5, SO2, NOx, VOCs, PAHs, CO, and CH4. The future emissions

reduction potential was projected based on scenario analysis to provide a theoretical basis and technical support for emission controls and the implementation of emission standards in heavily polluting industries.

METHODOLOGY AND DATA SOURCES Methodology

The “bottom–up” emission factors methodology was used to estimate the atmospheric emissions of air pollutants typically emitted by the coking industry (TSP, PM2.5, SO2, NOx, VOCs, PAHs, CO, and CH4). This methodology demonstrated a diverse approach for estimating the air pollution emissions of different industries and included production processes, enterprise scales, air pollution control devices, and geographical distribution. The historical trends in air pollutant emissions during the 12th five-year-plan (2011–2015) were summarized. The emissions were calculated by combining the best available activity data and the specific emission factors of different air pollutants. The emission inventory can be compiled as

3, , , , , , , , 10i y j k l i j k l p y

j k l p

E A EF (1)

where E is the emission of air pollutants (unit kt); A is the coke produced (kt); EF is the air pollutant emission factors during coking process (kg t–1); i denotes the air pollutant type; j denotes the coke oven types (including top–charging, stamp–charging, and heat recovery coke ovens); k denotes the heights of the coke oven’s carbonization chamber, classified as less than 4.3 m, 4.3–6.0 m, or more than 6.0 m; l denotes the Chinese provinces in which the oven is located; p denotes different coking processes including coal charging, coke pushing, coke transportation, coke quenching, and chimney emissions; and y denotes the year.

The potential emission reduction at the end of the 13th five-year-plan (2016–2020) was projected using the following equations: Pi = ∆Ei = ET,i – EC,i (2)

9, , , , ,

3, , , , , , ,

10

10

i j k l T j k i mj k l p

j k C i j k l p Cj k l p

E A FV EL

A EF

(3)

where P is the potential emission reduction (kt); FV is the flue gas volume in the coking process (m3 t–1), the FV parameters for different coking processes are presented in SI Table S5); EL is the air pollutant emission limitation defined by the emission standard of the coking industry (mg m–3); T is the target year; and C is the base year. Activity Data Collection and Analysis

Activity data statistics including the application ratio of different coke oven types, carbonization chamber types, and specific coke production data were collected from the


CCIA (CCIA, 2016d). In 2015, the worldwide coke production output was 652.41 Mt, of which China produced 68.6%. China’s coke production was 13.6–times that of Japan (33 Mt), which was the second largest producer. The yearly variations in coke production output among the world’s primary coke–producing countries are illustrated in Fig. 1. China produced 447.78 Mt of coke in 2015, with a coke production capacity of 686.76 Mt and an energy utilization rate of 65.2%, suggesting a surplus coke production capacity. Data on the coke output per production unit in China’s 29 administrative regions in 2015 are presented in SI Table S1 and reveal that the most productive regions were Shanxi, Hebei, Shandong, Shaanxi, and Inner Mongolia. Together, these five regions accounted for 54.9% of China’s total coke output.

The number of coking companies in China decreased from more than 730 in 2010 to 602 at the end of 2015; of these, 50 were heat recovery coke oven plants, 72 were semi–coke plants, and 480 were traditional coke plants (80 plants in the steel industry and 400 independent plants). The annual average coke production output of coking enterprises increased from 0.68 Mt per year in 2010 to 1.14 Mt per year in 2015; 367 companies had been admitted into the coking industry by the end of 2015 and had an output of 377.66 Mt, of which 328.73 Mt was generated from conventional coke ovens (55.4%). The respective percentages of all coke ovens that used various technologies in these admitted companies are presented in SI Fig. S1. Emission Factors

The coke production techniques used in the coking industry are generally divided into top charging, stamp–charging, and clean heat recovery. In particular, top–charging coke ovens are the most complex and most frequently applied. China’s relevant policies (of gradually eliminating outdated and highly polluting coke ovens with a height of less than

4.3 m and encouraging large–scale coke ovens), because of the distinct characteristics of pollutants emission from coke chambers with various heights, divide top–charging coke ovens into three height sizes: < 4.3 m, 4.3–6.0 m (4.3 m included), and > 6.0 m. The sizes of stamp–charging and heat recovery coke ovens are not categorized in detail because they differ slightly in specifications, have only been in use for a relatively shorter period of time, feature coke chambers of similar heights, and emit similar types of pollution. Recent domestic studies were used to obtain the air pollutant emission factors for the various coke production procedures (coal charging, coke pushing, transport, quenching and emissions through chimneys) of different types of coke ovens (see Tables 1 and 2) (Li, 2009; FNPSCD, 2010; Mu, 2013; MEP, 2014a, b).

Potential Emission Reduction Projection

In 1996, China stipulated the Emission Standard of Air Pollutants for Coke Ovens (GB 16171–1996), which only specified tier 1–3 emission limits for TSP, benzene–soluble organics, and benzo (a) pyrene that were released from coke ovens (SEPA, 1996). Because the present scale and quality of China’s coking industry have undergone substantial upgrades, this standard is limited in scope and thus cannot meet current requirements regarding to pollution prevention and control, environmental management, and environmental quality improvement, resulting in certain difficulties in the legal enforcement of environmental protection policy.

On January 6th, 2016, the CCIA announced the outline of the 13th five-year-plan concerning the development of the coking industry, which specified more stringent requirements for coking–industry development than those in the previous plan (NDRC and NEA, 2016). The objectives of the 13th five-year-plan and the status quo of China’s coking industry were used to conduct a scenario analysis of various types of coke oven. In addition, the emission limits proposed

Fig. 1. Historical trend of coke production in major countries of the world.


Table 1. Emission factors of TSP, SO2, and NOx from different coking technology and production processes, kg t–1.

Production procedure Air pollutants

Top charging coke oven (< 4.3 m)

Top charging coke oven (4.3–6.0 m)

Top chargingcoke oven (> 6.0 m)

stamp charging coke oven

Heat recoverycoke oven

Coal charging TSP 1.98 0.12 0.10 0.12 1.90 (0.17–3.79) (0.17–3.79)

Coke pushing 2.05 0.13 0.13 0.13 2.05 (0.12–3.98) (0.12–3.98)

Transport 1.46 0.12 0.11 0.12 1.46 (0.10–2.77) (0.14–2.77)

Coke quenching 0.08 0.08 0.07 0.06 0.08 (0.06–0.09) (0.05–0.11) (0.04–0.11) (0.05–0.07) (0.07–0.09)

Chimney exhaust 3.70 × 10–3 0.02 0.01 0.02 0.26 (0.00–0.03) (0.00–0.03) (0.08–0.44)

– SO2 0.94 0.83 0.08 0.88 3.04 (0.10–1.76) (0.07–1.60) (0.06–0.09) (0.07–1.70) (1.05–5.04)

NOx 0.22 0.40 0.36 0.41 0.29 (0.03–0.41) (0.37–0.43) (0.32–0.39) (0.38–0.44) (0.18–0.39)

Table 2. Emission factors of VOCs, PAHs, CO, and CH4 from different coking technology and production processes, kg t–1.

Production procedure PM2.5 VOCs PAHs CO CH4 Coal charging – – – 0.03 0.15 Coke pushing – – – 0.26 3.36 × 10–3 Transport – – – – – Coke quenching – – – 4.26 2.21 × 10–3 Chimney exhaust – – – – – Whole process 5.20 2.96 0.63 × 10–3 4.55 0.16

in the Emission Standard of Pollutants for the Coking Chemical Industry (GB 16171–2012) were adopted to estimate the emission factors for air pollutants that will be released from these coke ovens in 2020 (MEP, 2012; NDRC and NEA, 2016). RESULTS AND DISCUSSION Temporal and Spatial Distribution Characteristics

The historical trends and spatial distribution of the atmospheric emissions of typical air pollutants from the coking industry during 2011–2015 are illustrated in Fig. 2. The 2015 emissions of typical air pollutants were estimated to be 368.36 kt for TSP, 23.28 kt for PM2.5, 402.54 kt for SO2, 174.43 kt for NOx, 1325.42 kt for VOCs, 28.24 kt for PAHs, 2036.43 kt for CO, and 71.68 kt for CH4, respectively, and the average annual growth rate was 1.1% during the 12th five-year-plan. In the implementation of the Access Conditions of the coking industry (revised in 2014), backward production capacity was banned and optimized, which caused a substantial moderation of the rate of increase, from 7.1% in 2013 to 0.8% in 2014 (MIIT, 2014). Moreover, emission limits for most coking enterprises that were stipulated by the emission standard caused a decrease in emissions in 2015 of 6.1% (MEP, 2012).

As illustrated in Fig. 2, air pollutant emissions were concentrated in Shanxi, Hebei, Shandong, Shaanxi, and Inner Mongolia, which are located in Northern China, and these regions accounted for 54.8% of total emissions. This

suggests that these five regions, in which independent coking companies are highly concentrated, accounted for more than half of China’s total coke output. Emission Characteristics of Various Coking Procedures and Types of Coke Oven

Due to the lack of data on some emission factors, the present study estimated the emissions of only three air pollutants (TSP, SO2, and NOx) by comparing emissions from various types of coke oven and using various coking procedures, namely coal charging, pushing, transport, and quenching, in addition to emissions through chimneys (Fig. 3) (Li, 2009; FNPSCD, 2010; Mu, 2013; MEP, 2014a, b). The estimation results demonstrated that top–charging coke ovens with heights 4.3–6.0 m and stamp–charging coke ovens were the major sources of air pollutant emissions because they were highly productive and exhibited relatively high emission factors for the three air pollutants. TSP was mainly emitted from coal charging and coke pushing and transport, whereas coke quenching and coal charging were the main contributors of CO and CH4, respectively.

Coke is typically produced in China using conventional mechanical coke ovens with horizontal chambers or using heat recovery coke ovens incorporating stamp–charging technology, which produce air pollutants primarily from coal charging, coke pushing, quenching, and desulphurization (Wang, 2015; CCIA, 2016d).

Coal charging produces three types of exhaust gas: (1) hot air excluded from coking chambers during coal


Fig. 2. Temporal and spatial distribution of air pollutant emissions from coking industry.

Fig. 3. The emission of typical air pollutants of different coking procedures and types of coke oven.

charging; (2) raw gas generated from the volatilization and decomposition reactions of coal in contact with highly heated coking chamber walls; and (3) water vapor produced from the vaporization of moisture in the raw coke. Ascending hot air in the oven, raw gas produced from coal decomposition, and water vapor leaking through the coal

charging hole or oven doors can release substantial smoke and dust that severely pollute the environment. Research indicates that, on a short-term basis, coal charging alone produces a TSP amount seven times that produced from coking procedures, and accounts for 50.0%–60.0% of the total pollutant emission from the overall coking process


(Wang, 2015). During coke pushing, TSP can leak during repeated

oven-door opening and the pushing of coke from the coke oven. The emission of pollutants from the coke oven during this process is characterized by multiple leak points, wide dissemination, dispersed distribution, multiple pollutant types, high degrees of hazard, and difficulty in hazard prevention and control.

Coke quenching is mostly performed using two methods: wet and dry quenching. Wet quenching involves spraying quenching water onto red-hot coke delivered into the quenching tower, during which considerable water evaporation and pollutant effusion occur. This method is currently employed worldwide because of its simplicity and low cost. Dry quenching can be used to recover the sensible heat of coke and produces less pollutant than wet quenching. In China, dry quenching is used to produce only 32.0% of the total domestic coke production. Emission Comparison of Heavy Polluting Industries and Uncertainty Analysis

Data from several highly polluting industries in China that are the target industries for national pollution control (i.e., the thermal power, ceramics manufacturing, steel smelting, and coking industries) were collected and their air pollutant emissions compared (Table 3) (Chen et al., 2014; Wu et al., 2015a, b; Wang et al., 2016; Hua et al., 2016). Of these industries, the coking industry emitted the highest amount of VOCs. The emissions estimation of the study of Wu et al. (2015a) contained the emission processes of sintering, pelleting, iron-making, steel-making, and steel rolling processes of iron and steel manufacturing industry. In China, approximately 35% coke production capacity concentrates in iron and steel manufacturing enterprises in 2015. However, the emissions of coking process which belongs to iron and steel manufacturing industry were not considered.

Monte Carlo simulations were employed to quantify the uncertainties in emission estimates (Zheng et al., 2009; Zhao et al., 2011; Cheng et al., 2015). A normal distribution with a coefficient of variation (CV, the standard deviation divided by the mean) of 30.0% was assumed for coke production. With regard to the uncertainties in the estimates, we performed a sensitivity analysis of the total emissions

of various pollutants. Given that uncertainty values were not available for some of the inputs, assumed values are assigned to each input to test the sensitivity of the results to each. The uncertainty of different model inputs (SI Table S2) was assigned randomly. The overall uncertainties were in the approximate range –110.3% to +90.8%. The large uncertainties were mainly because of incomplete investigations and inadequate field test data for the activity data and coking industry emission factors. Field tests of the characteristics of air pollutants emitted by the coking industry are urgently needed for future research. Emission Reduction Potential Analysis and Relevant Pollution Control Proposals

The objectives of the 13th five-year-plan and the current status quo in China’s coking industry (see SI Table S3) were used to estimate the production output, percentage of various coke ovens used, and air pollutant emission factors in 2020 (SI Fig. S2 and SI Table S4) (CCIA, 2016c; NDRC and NEA, 2016; MEP, 2016). The estimation results revealed that the number of top-charging coke ovens with heights < 4.3 m will decrease from 3.0% 2015 to becoming completely banned in 2020. By contrast, the number of top–charging coke ovens with heights > 6 m will increase from 6.0% in 2015 to 35.0% in 2020. The percentages of other oven types used will also change. Fig. 4 presents the estimated potential emission reduction of typical air pollutants generated from the coking industry that will occur under the 13th five-year-plan. The scenario analysis revealed that, by the end of the plan, the emission of TSP, SO2, and NOx from China’s coking industry will be reduced by 82.9%, 94.4%, and 6.9%, respectively, down to 62.84, 22.72, and 162.32 kt.

To realize the objectives of the 13th five-year-plan concerning the coking industry and reduce the emission of air pollutants, clean production technologies must be further promoted to minimize pollution at its source, increase resource utilization rates, reduce or prevent the generation and emission of pollutants, and thereby reduce environmental hazards and the risks to human health. Because coke production involves multiple pollution-producing steps and its air pollutant emissions are severe, highly economical technologies must be employed for all potential pollution-producing steps.

Table 3. The comparison of the emissions of typical air pollutants of heavy polluting industries.

Air pollutants Power plants Cement production Iron and steel manufacturing Coke production TSP 1433 3866 1886 368.36 PM2.5 622 1700 555 23.28 SO2 7251 815 2222 402.54 NOx 8067 2042 937 174.43 VOCs 260 254 1325.42 PAHs 28.24 CO 4843 2036.43 CH4 71.68 Base year 2011 2012 2012 2015 Data sources Chen et al., 2014;

Wu et al., 2015b Hua et al., 2016 Wu et al., 2015a This study


Fig. 4. Projection of emission reduction potential of typical air pollutants until 2020.

A number of pollution control technologies and methods can be used in the coking industry (MEP, 2010; CCIA, 2016d). The specific control technologies for different coking procedures and their corresponding air pollution control effects are illustrated in SI Table S7. Approaches for coal storage and blending include large coal storage silos, pneumatic selective crushing, coal moisture control (CMC), CMC integrated with pneumatic classification and separation, and the coal blending coking technique. For coking procedures, large coke ovens (height of coking chamber ≥ 6 m, volume ≥ 38.5 m3, top-charging) and the stamp-charging coking technique (height of coking chamber ≥ 5.5 m) are preferable. Coke quenching techniques that facilitate the control of pollutant emissions include dry quenching, low-moisture quenching, and conventional wet quenching. Control methods feasible for use in coal–gas purification include large coal storage silos, pneumatic selective crushing, CMC, CMC integrated with pneumatic classification and separation, and the coal blending coking technique. Pollution can be controlled during coal-gas purification by using desulfurization and decyanation techniques relying on the vacuum carbonate, Sulfiban, and HPF processes. Urban air particulate matter can be mitigated using dust-removal filter bags, wind-proof dust nets, large ground stations employing dry dust-removal and purification technologies, gas collection using side-mounted suction tubes, and dust-removal technologies using fog-removing devices and baffle plates, all of which have a dust-removal efficiency of more than 99.0%. To meet the coking emission standard, VOCs emissions must be controlled by using absorption technologies to collect organic solvents or employing catalytic and thermal combustion technologies. CONCLUSIONS

In the present study, a comprehensive emission inventory of typical primary air pollutants (TSP, PM2.5, SO2, NOx, VOCs, PAHs, CO, and CH4) from the coking industry was established by using the bottom-up emission-factors methodology for the period 2011–2015. The emissions were estimated at 368.36 kt for TSP, 23.28 kt for PM2.5,

402.54 kt for SO2, 174.43 kt for NOx, 1325.42 kt for VOCs, 28.24 kt for PAHs, 2036.43 kt for CO, and 71.68 kt for CH4 in 2015 at an annual average growth rate of 1.1% during the 12th five-year-plan. These air pollutants were mainly concentrated in northern areas of China such as Shanxi and Hebei, where coke is produced in considerable volume and coking companies independently operate plants that use relatively less advanced technology. Coal charging, coke pushing, and transport contributed to the primary TSP emissions, while coke quenching and pushing were the main contributors of CO and CH4, respectively. Moreover, future emissions and the potential reduction in typical air pollutants during the 13th fiv-year-plan (2016–2020) were projected in the scenarios for coke production and control technologies by considering the development plan and emission restrictions of the coking industry. The reduction potential of the emissions of TSP, SO2, and NOx will reach 82.9%, 94.4%, and 6.9%, respectively, by the end of 2020. In addition, to support the emission-reduction potential and enhance air quality, a series of feasible control proposals for each pollutant-discharge procedure has been illustrated. ACKNOWLEDGMENTS

This work is supported by the National Natural Science Foundation of China (No. 21407122 and No. 21507024), the Technology Strategy Project on Pollution Reduction from the Chinese Academy For Environmental Planning (No. 2016A068), the General Financial Grant from the China Postdoctoral Science Foundation (No. 2015M580631), the General Financial Grant from Henan Postdoctoral Research Sponsorship (No. 2015074 and No. 2015077), and the Youth Science Foundation (No. 2014QK23) of Henan Normal University. The authors wish to thank the editors and the anonymous reviewers for their valuable comments and suggestions on our paper. SUPPLEMENTARY MATERIAL

Supplementary data associated with this article can be


found in the online version at http://www.aaqr.org. REFERENCES Chen, L.H., Sun, Y.Y., Wu, X.C., Zhang, Y.X., Zheng,

C.H., Gao, X. and Cen, K.F. (2014). Unit–based emission inventory and uncertainty assessment of coal–fired power plants. Atmos. Environ. 99: 527–535.

Cheng, K., Wang, Y., Tian, H.Z., Gao, X., Zhang, Y.X., Wu, X.C., Zhu, C.Y. and Gao, J.J. (2015). Atmospheric emission characteristics and control policies of five precedent–controlled toxic heavy metals from anthropogenic sources in China. Environ. Sci. Technol. 49: 1206–1214.

China Coking Industry Association (CCIA) (2016a). List of enterprises that conform to, change and cancel the name of the announcement of the coking industry. http://www.cnljxh.com/zcfg/2017/1/13/16000136000j835i.html (in Chinese).

China Coking Industry Association (CCIA) (2016b). List of enterprises that conform to, change and cancel the name of the announcement of the coking industry. http://www.cnljxh.com/zcfg/2017/1/13/16000136000j835i.html (in Chinese).

China Coking Industry Association (CCIA) (2016c). The interpretation of the coking industry "13th Five-year-plan". http://www.cnljxh.com/ZHFW/2016/2/24/260002 460002KD1G.html (in Chinese).

China Coking Industry Association (CCIA) (2016d). Annual report of coke market development of China 2016. China Economic Press, Beijing, China (in Chinese).

Chinese Academy of Engineering (CAE) (2011). Medium and long–term research and development strategy on energy in China, Science Press, Beijing, China (in Chinese).

Compilation Committee of the First National Pollution Source Census Data (FNPSCD) (2010). The handbook of emission factors of industrial pollution sources of the first national pollution source census. China Environmental Science Press, Beijing, China (in Chinese).

Ge, X.H., Chang, L.P., Yuan, J., Ma, J.C., Su, X.D. and Ji, H.J. (2016). Greenhouse gas emissions by the Chinese coking industry. Pol. J. Environ. Stud. 25: 593–598.

He, Q.S. (2006). Composition patterns, emission factors and preliminary emission estimation of particulates and volatile organic compounds from coking processes in China. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China (in Chinese).

Hu, M., Pauliuk, S., Wang, T., Huppes, G., van der Voet, E. and Müller, D.B. (2010). Iron and steel in Chinese residential buildings: A dynamic analysis. Resour. Conserv. Recycl. 54: 591–600.

Hua, S.B., Tian, H.Z., Wang, K., Zhu, C.Y., Gao, J.J., Ma, Y.L., Xue, Y.F., Wang, Y., Duan, S.H. and Zhou, J.Y. (2016). Atmospheric emission inventory of hazardous air pollutants from China's cement plants: Temporal trends, spatial variation characteristics and scenario projections. Atmos. Environ. 128: 1–9.

Huo, H., Lei, Y., Zhang, Q., Zhao, L. and He, K. (2012).

China’s coke industry: Recent policies, technology shift, and implication for energy and the environment. Energy Policy 51: 397.

International Agency for Research on Cancer (IARC) (1984). Polynuclear aromatic compounds: Part 3, Industrial exposures to aluminum production, coal gasification, coke production, and iron steel founding. International Agency for Research on Cancer, Lyon, France.

International Agency for Research on Cancer (IARC) (2002). IARC monographs on the evaluation of the carcinogenic risk of chemicals to humans. http://monographs.iarc.fr.

Li, C.C. (2009). Characterization of air pollutants emitted from coking production. Southwest University, Chongqing, China (in Chinese).

Liu, G.R., Zheng, M.H., Liu, W.B., Wang, C.Z., Zhang, B., Gao, L.R., Su, G.J., Xiao, K. and Lv, P. (2009). Atmospheric emission of PCDD/Fs, PCBs, hexachlorobenzene, and pentachloro benzene from the coking industry. Environ. Sci. Technol. 43: 9196–9201.

Lloyd, W.L. (1971). Long-term mortality study of steelworkers. Respiratory cancer in coke plant workers. J. Occup. Environ. Med. 13: 53–68.

Ministry of Environmental Protection of the People’s Republic of China (MEP) (2010). Guide for the best practicable technology for prevention and control of coking process pollution in iron and steel industry (Trial). http://www.zhb.gov.cn/gkml/hbb/bgg/201012/t20101230_199308.htm (in Chinese).

Ministry of Environmental Protection of the People’s Republic of China (MEP) (2012). Emission standard of pollutants for coking chemical industry. http://kjs.mep. gov.cn/hjbhbz/bzwb/shjbh/swrwpfbz/201207/t20120731_234146.shtml (in Chinese).

Ministry of Environmental Protection of the People’s Republic of China (MEP) (2014a). Technical guide for the preparation of emission list of primary particles of atmospheric fine particles (Trial). http://www.zhb.gov.cn/gkml/hbb/bgg/201408/t20140828_288364.htm (in Chinese).

Ministry of Environmental Protection of the People’s Republic of China (MEP) (2014b). Technical guidelines for the preparation of emission inventories of atmospheric volatile organic compounds (Trial). http://www.zhb.gov.cn/gkml/hbb/bgg/201408/t20140828_288364.htm (in Chinese).

Ministry of Industry and Information Technology of the People’s Republic of China (MIIT) (2014). Access conditions of Coking industry (revised in 2014). http://www.miit.gov.cn/n1146290/n1146397/c4231310/content.html (in Chinese).

Mu, L. (2013). Emission characteristics of particulates and polycyclic aromatic hydrocarbons from coking processes. Taiyuan University of Technology, Taiyuan, China (in Chinese).

National Bureau of Statistics of China (NBSC) (2016). China statistical yearbook 2016, China Statistics Press, Beijing, China, 2016 (in Chinese).


National Development and Reform Commission (NDRC) and National Energy Administration (NEA) (2016). Notice on issuing the coal industry development in "13th Five-year-plan". http://www.sdpc.gov.cn/gzdt/201612/ t20161230_833726.html (in Chinese).

State Environmental Protection Administration of China (SEPA) (1996). Emission standard of air pollutants of coke ovens. GB 16171–1996. http://www.doc88.com/p-7496287833740.html (in Chinese).

Tian, H.Z., Cheng, K., Xu, J.Y. and Hao, J.M. (2010). Multi-level fuzzy comprehensive assessment of desulfurization technologies for coking making industry. J. China Coal Soc. 35: 1542–1547 (in Chinese).

U.S. Environmental Protection Agency (US EPA) (1999). Compendium method TO–13A Determination of Polycyclic Aromatic Hydrocarbons(PAHs) in ambient air using gas chromatography/mass spectrometry (GC/MS), Environmental Protection Agency, Cincinnati, OH, U.S.

Wang, X.Q. (2015). Coking process (3rd version). Chemical Industry Press, Beijing, China (in Chinese).

Wang, Y., Cheng, K., Tian, H.Z., Yi, P. and Xue, Z.G. (2016). Emission characteristics and control prospects of primary PM2.5 from fossil fuel power plants in China. Aerosol Air Qual. Res. 16: 3290–3301.

Wu, W.J., Chang, X., Xing, J., Wang, S.X. and Hao, J.M. (2017). Assessment of PM2.5 pollution mitigation due to emission reduction from main emission sources in the Beijing–Tianjin–Hebei region. Environ. Sci. 38: 867–875 (in Chinese).

Wu, X.C., Zhao, L.J., Zhang, Y.X., Zheng, C.H., Gao, X. and Cen, K.F. (2015a). Primary air pollutant emissions and future prediction of iron and steel industry in China. Aerosol Air Qual. Res. 15: 1422–1432.

Wu, X.C., Huang, W.W, Zhang, Y.X., Zheng, C.H., Jiang, X., Gao, X. and Cen, K.F. (2015b). Characteristics and uncertainty of industrial VOCs emissions in China. Aerosol Air Qual. Res. 15: 1045–1058.

Zhang, W.H. (2000). American experts talk about future coke making industry. Fuel Chem. Process. 31: 225–228 (in Chinese).

Zhao, Y., Nielsen, C.P., Lei, Y., McElroy, M.B. and Hao, J.M. (2011). Quantifying the uncertainties of a bottom–up emission inventory of anthropogenic atmospheric pollutants in China. Atmos. Chem. Phys. 11: 2295–2308.

Zheng, J.Y., Zhang, L.J., Che, W.W., Zheng, Z.Y. and Yin, S.S. (2009). A highly resolved temporal and spatial air pollutant emission inventory for the Pearl River Delta region, China and its uncertainty assessment. Atmos. Environ. 43: 5112–5122.

Zhu, X.L., Wang, Y.Q., Liu, W.L. and Zhu, T. (2001). Study on the characteristics of PAHs source profile of coke plant. China Environ. Sci. 21: 266–269 (in Chinese).

Received for review, April 18, 2017 Revised, September 24, 2017 Accepted, November 2, 2017

Documents

Analysis of Reduction Potential of Primary Air Pollutant