Emission Characteristics of Air Pollutants by Typical Production Process in Iron and Steel Enterprises

Transcription

1 Emission Characteristics of Air Pollutants by Typical Production Process in Iron and Steel Enterprises Xue Zhigang, Ma jinghua, Li Chongqing, Duan Jingchun Chinese Research Academy of Environmental Sciences (CRAES) May. 12, 2010

2 Background Content Test Plan Test Results Conclusion & Suggestions

3 Background Output Pollutant Emission 10,000 tons ) 吨万 ( 量产 10,000 tons 年 年 年 年 年 年 600 SO2 smoke 500 ) 二氧化硫 sulfur 烟尘 dust dioxide 吨 400 吨万 ( 量放排 年 1997 年 年 年 年 年 In 1995, China's steel output was 95 million tons, 352 million tons in 2005, and 500 million tons in 2008, it is estimated that by 2010, China's steel output will reach 550 million tons; in 2005, the SO 2 and dust emissions by China's steel industry were 4,862,700 tons and 1,550,400 tons respectively, with increases of 3,546,700 tons and 1,130,800 tons respectively over 1995.

4 Typical Production Process Flow of Iron & Steel Industry PM,CO,SO2,NOx Ore Sintering Transport & Storage Crushing Coal Coking Crushing Or Screening Iron Making Hot Metal Pretreatment Steel- Making Steel Color Treatment Casting Or Contin- Uous Casting Heating Hot Scarfing Hot Rolling & Cold Rolling Steel Product,NOx Lime Roasting

5 Emission Factors of Air Pollutants by Iron & Steel Industry Product Pollutant Unit Pollutant Producing Factors Pollutant Emission Factors Coking Sulfureted hydrogen Kg/t coke Sinter Sulfur dioxide Kg/t sinter Kg/t sinter Iron Making Kg/t iron Steel Making Kg/t steel (Open-hearth Furnace) Steel Making(Converter) Kg/t steel Steel Making(Electric Furnace) Kg/t steel From:Industrial Pollutants Producing and Emission Factors Handbook Compiled by SEPA in 1996.

6 Test Method Particulate Size Distribution Sampling and Measuring System Sampling by filter cartridge, Qingdao Laoyin Model 3012H Automatic Smoke (Flue gas) Sampling and Measuring System. Inhalable PM Electrical Low Pressure Impactor (ELPI) by Dekati Ltd., Finland ELPI can measure PM with aerodynamic diameter from 28nm to 9.9µm,and classify them into 12 stages for separate counting Sampl -ing Pump PM 10 Pre-cutter (Whirlwind Remove) ELPI Sampling Gun Stage Cutpoint Diameter (µm) Geometric Mean Diameter (µm)

7 Chemical Composition Analysis Method of Particulate Matter Elements Analysis: Microwave-assisted digestion+ inductively coupled plasma mass spectrometry (ICP-MS) OC/EC Analysis: Sunset Carbon Analyzer (Sunset Laboratory Inc., USA), thermophotometry. Ion Analysis: Dionex-600 Ion Chromatographic Analyzer Data Analysis and Processing ELPI attached working sheet

8 NMHCs Sampling Coke Oven Roof Sampling: Sampling canister: check the canister before sampling, ensure that there is no target compound in it, then vacuum it, open the valve till the internal and external air pressure are the same, start sampling, control the air flux by adjusting flowlimiting valve to prolong sampling time, there is a filter (cotton) in front end for filtering fine dust in the air, tighten the valve after sampling. Flue Gas Sampling Before sampling, connect the pump with PTFE pipe to extract smoke air until all the air in the pipe and pump are replaced, immediately connect the pipe with sampling canister for sampling.

9 NMHCs Analysis Sampling Canister Cryogenic Focusing Controlled by quality flow controller to stabilize the extracting flux GC/MSD Analysis Prethickening System Two grade cold trap for removing H2O and CO2

10 Test Plan Sampling Site Sintering Plant Charge end (head) of sintering machine, Sintering machine tail. Collector :4 electric fields ESP. Iron Plant Blast furnace cast house Collector :FF. Flue Gas ESP/FF Induce Draft Fan Chimney

11 Coking Plant Sampling Site Coal Tower Coal Blending Raw Gas System Coal Charger Coal Charging Collector Coke Pushing Collector Exhaust Gas by Coal Charging Exhaust Gas by Coke Recovery Gas Puri- Fication syst em Coke Pusher Coke Oven's Carbonization Chamber Coke Oven's Heating System Red Coke Coke Guide Coke Quenching Car Coke Quenching Tower Coke System Coke Quenching Collector Screening Exhaust Gas by Coke Quenching Gas Transmission Recycled Gas Coal Blast Furnace Gas Air 烟囱 Coke Transport

12 Sampling Frequency Site Collector Location Sampling PM 10 Diameter- Graded Sampling Sinter -ing Plant 360m 2 Head of Machine Tail of Machine ESP In front of Removal Device Behind Removal Device In front of Removal Device Behind Removal Device 3 times by Glass fibrecartridge filter 3 groups Aluminium film/teflon film/quartz film Iron Plant 2200m 3 cast house FF In front of Removal Device Behind Removal Device

13 Sampling Equipment Applied Coke Oven Roof: PM Sampler Pump, Sampling canister Sinter machines head and tail, iron making, coal loading, coke pushing, coke quenching,chimney: Qingdao Laoying Automatic Automatic Smoke (Flue gas) Sampling and Measuring System. ELPI

14 Test Results Emission Concentration and Removal Efficiency at Each Test Site Concentration In Front of /Behind Removal(mg/m3) National Standard GB Site In front of Removal Behind Removal Removal Efficiency(%) Type of Furnace Level of Stand -ard Limited Value (mg/m 3 ) Decision Outcomes Head of Machine Tail of Machine 270.3± ± ± ± Sinter Machine (head,,tail) Meet Standard Meet Standard Blast Furnace Cast house ± ± & Blast Furnace cast house Meet Standard

15 Size Distribution of Inhalable PM Mass Concentration Machine head, in frond of dust removal device Machine tail, in frond of dust removal device Machine head, behind dust removal device Machine tail, behind dust removal device

16 Removal Efficiency of Different Particulate Size Stages at Sampling Sites PM Mass Concentration at Machine Head (mg/m³) PM Mass Concentration at Machine Tail (mg/m³) PM Mass Concentration at Cast House (mg/m³) PM 2.5 PM 10 PM 2.5 PM 10 PM 2.5 PM 10 In front of Removal Device Behind Removal Device Removal Efficiency% At all sites under this study, the law of dust removal efficiency appeared to be: PM 2.5 <PM 10 <Total dust,esp and FF dust collector have higher removal efficiency on course PM in comparison with fine PM.

17 Chemical Composition Analysis on PM Main chemical composition of PM emitted from sintering machine head: SO 4 2- >K>OC>Cl - >Ca>Pb>Si>Fe>Al>Na Main chemical composition of PM emitted from sintering machine tail: Fe >Ca> Si> OC> SO 4 2- > Cl-> Al>Na >K> Mg Main chemical composition of PM emitted at cast house: Si>Fe>OC>SO 4 2- >Al>Cl->Ca >K>Na >Mg

18 PM Production and Emission per Unit of Product Pollutant Productionat Machine Head Kg/t-Sinter Emission at Machine Head Kg/t-Sinter Productionat Machine Tail Kg/t-Sinter Emission at Machine Tail Kg/t-Sinter Productionat Cast House Kg/t-Iron Emission at Cast House Kg/t-Iron PM PM Proportion of PM 10, PM 2.5 in total dust emission at all Sites Particle Diameter In Front of Removal Device, Machine Head Behind Removal Device, Machine Head In Front of Removal Device, Machine Tail Behind Removal Device, Machine Tail In Front of Removal Device, Cast House Behind Removal Device, Cast House PM 10 (%) 51.23% 99.38% 7.81% 43.20% 4.74% 50.84% PM 2.5 (%) 43.73% 85.00% 6.20% 36.46% 4.09% 45.68%

19 Test Results Air Pollutant Concentration on Coke Oven Roof 3 mg/ m Air pollutant concentration on coke oven roof is far below national standard Sample TSP BSO B[a]P CH NMHCs TSP BSO BaP CH4 NMHCs Average Concentration mg/m 3 Standard Grade

20 Pollutant Emission Concentration of Coal-charging, coke Pushing and quenching mg/ m mg/m3) ( 200 度 SO2 浓 时间 min TSP SO2 CH4 CO NMHCs mg/m3) ( 4000 度 CO 浓 Emission: Coke pushing>coke quenching >coal charging CH4, NMHCs emission concentration in coal charging is far greater than it in other processes Coal 熄焦烟气浓度周期变化 Coke Charging Pushing Coke Coke Oven Roof 装煤出焦熄焦焦炉顶环境 Quenching Ambient Airt mg/m 3 Process Average Coal Charging Maximum Minimum Minimum SD* Average Coke Pushing Maxim um Minimum SD Average Coke Quenching Maximum SD SO CO Smoke CH NMHCs

21 NMHCs Emission Characteristics 浓度 mg/ m3 Concentration mg Alkane 烷烃 Benzene 苯系物 Series 烯烃乙炔 Alkene Ethyne Coal Coke Coke Coke Oven Charging 装煤出焦 Pushing Quenching 熄焦炉顶 Roof 环境 Ambient Air The main composition of NMHCs are: ethene, benzene, ethane, propylene, toluene, dimethylmethane, butylene etc.

22 Emission Characteristics of Benzene Series μg/m 3 Coke 出焦 Quenching 熄焦焦炉顶环境 Ambient Air 装煤 Coal 出焦 Coke Coke 熄焦焦炉顶 Coke 环境 Charging Coke Pushing Pushing Quenching Coke Oven Roof Oven Roof Ambient Air 1, 2, 3- 三甲基苯 TMB 1, 2, 4- 三甲基苯 TMB 邻乙基甲苯 1, 3, 5- 三甲基苯 TMB ethyltoluene 对乙基甲苯 间乙基甲苯 propylbenzene 丙基苯 异丙基苯 邻二甲苯 间 / 对二甲苯 ethylbenzene 乙苯 苯乙烯 甲苯 苯 C9H12 C9H12 C9H12 C9H12 o-xylene m-xylene,p-xylene isopropyl benzene styrene toluene benzene

23 Emission Characteristics of Particle Matter by Coking mg/m 3 Coal Charging % Coke Pushing % Coke Quenching % PM PM PM PM emitted by coking are mainly PM2.5 or below.

24 Conclusion Measurements on three emission sites, i.e. sinter machine head, tail and cast house in iron plant showed that emission concentration of dust meet the national standard. In all sites, PM 2.5 in flue gas (behind dust removal device) have a high proportion in PM i.e. over 80%,it means: the main composition of PM by iron and steel industry s typical producing process is PM 2.5. The main chemical composition of PM in the three emission sites are similar, such as Fe, Si, Ca, K, Al, Na, SO 4 2-, Cl- and high proportion of organic carbon. The concentration of air pollutant from coke oven s roof is far below national emission standard.the NMHCs found in smoke samples collected in every process of coking and at coke oven proof are mainly alkane, cyclanes, alkene, ethyne and benzene series At coal charging site, CH4 and NMHCs emission are much greater than other test sites; while the composition of pollutant by coke pushing and on coke oven roof is mainly benzene series; as for coke quenching process, the main composition are alkane and ethyne.

25 Conclusion Based on the test results, air pollutant emission level by coking process is obtained, it includes SO 2, smoke dust, CH4 and NMHCs,which will be very useful to obtain emission factor of coking sector In coking process, PM10 emitted mainly consists PM2.5 or below. The PM emitted by coal charging process mainly consists of OC, Si, SO42-, Ca; The PMemitted by coke pushing process mainly consists EC, OC, Ca, K, Al; The PM emitted in coke quenching process mainly consists OC, Ca.

26 Suggestions It is very important to improve the standards on iron and steel industry s pollutant emission, for example: set limited value for PM 10 and PM 2.5 Concentration. Application of large capacity coke oven: reduced operation frequency will result in less leak points and less pollutant emission.popularizationof dry quenching:by dry quenching, around 80% of sensible heat of red coke can be recovered, the coke quality will be improved while the air pollutant can be greatly reduced. Strictly Implement the industry policy, wash out backward cokingprocess. Strengthen pollutant prevention capability, guide coking industry s technology upgrade and structure optimization.

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