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Emission Characteristics of Organic Pollutants During Co-processing of Coal Liquefaction Residue in Texaco Coal-water Slurry Gasifier Xuebing Li, Li Li, Zechun Huang, Da-Hai Yan, Hongjin Yu, and Jie He Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03395 • Publication Date (Web): 08 Jan 2018 Downloaded from http://pubs.acs.org on January 8, 2018
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Emission Characteristics of Organic Pollutants during Co-processing of Coal Liquefaction Residue in Texaco Coal-water Slurry Gasifier
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Xuebing Li†, Li Li†， *, Zechun Huang†, Dahai Yan†, Hongjin Yu†, Jie He†
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5 6
†
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research
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Academy of Environmental Sciences, Beijing 100012, China
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Submitted as manuscript to Energy & Fuels
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*Corresponding Author: Li Li
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E-mail:
[email protected] 11
Phone: +86-10-84915182
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Fax: +86-10-84913903
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Number of pages:
24
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Number of figures:
7
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Number of tables:
3
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Number of words:
6920 word equivalents
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TOC Art
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Abstract: Field tests were conducted to research the emission characteristics and environmental
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risk of organic pollutants during co-processing of coal liquefaction residue (CLR) in Texaco
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coal-water slurry gasifier. Changes of temperature, pressure and syngas composition in the
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gasifier were recorded under blank condition (without mixing CLR in the slurry) and test
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condition (15% CLR were mixed into the slurry). Also the toxicity equivalent concentration of
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16 kinds of polycyclic aromatic hydrocarbons (PAHs) and Polychlorinated dibenzo-p-dioxins
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(PCDDs) and Polychlorinated dibenzofurans (PCDFs) and the concentration of volatile organic
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compounds (VOCs) in all the solid waste, liquid and gas emissions under two conditions were
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analyzed. Results showed that during the co-processing process, the pressure and syngas
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production of the gasifier were essentially unaffected, the temperature in gasifier increased 5-11℃
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and promoted the formation of H2 and CO. The concentration of PAHs in part of the gas
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emission, liquid emission and solid waste increased 1.0-1.3µg/m3, 19ng/L and 1.4-2.3mg/kg
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respectively during the co-processing process, but the total toxicity equivalent concentration
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were still far lower than relevant standard limits, the emission of PAHs during co-processing of
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CLR in Texaco coal-water slurry gasifier has low environmental risk. The concentration of
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PCDD/Fs in liquid emission and solid waste decreased 0.002ng TEQ/L and increased 0.0002µg
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TEQ/kg respectively, the environmental risk was rather low. The concentration of VOCs in gas
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samples were far below the blank condition under test condition, in the liquid emission and solid
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waste were mostly not detected or below the detection limits, VOCs emission in the
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co-processing process has low environmental risk.
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1 Introduction
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Polycyclic aromatic hydrocarbons (PAHs) are classified as priority control pollutants in
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many countries because of its carcinogenicity, teratogenicity, and mutagenicity, which mainly
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comes from incomplete combustion of fuels such as coal and oil.1-3 Dioxins include
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Polychlorinated dibenzo-p-dioxins(PCDDs) and Polychlorinated dibenzofurans(PCDFs) are
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persistent organic pollutants under the Stockholm Convention because they are toxic, persistent
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and bioaccumulative, which can be performed unintentionally during the incineration of
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industrial waste and various chlorinated-chemical industrial processes.4-6 Volatile organic
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compounds(VOCs) which are the mainly cause of photochemical smog can also produced in the
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high temperature combustion and gasification process.7 PAHs, PCDD/Fs and VOCs are the most
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concerned organic pollutants in research.
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Coal liquefaction residue(CLR) is solid waste produced in the process of coal liquefaction
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production after quenching, high pressure and medium pressure separation, normal pressure and
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vacuum fractionation to separate low boiling point oil.8 The concentration of PAHs in CLR is
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higher than in the coal, and the CLR also has a large number of unreacted coal to be recycled.9
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With high calorific value, the carbon burning efficiency of CLR can reach more than 90%. Due
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to the conventional combustion mode, it is difficult to use the carbon effectively under its low
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softening temperature.10 There is no essential difference between the product of coal and CLR
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gasification according to the study on characteristics of syngas from 5 kinds of CLR.11,12
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USERDA13,14 analyzed the physical properties and chemical composition of 3 kinds of the CLR,
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and conducted gasification experiment in Texaco gasifier and obtained yield and composition of
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syngas. All above studies only focused on the syngas quality of the CLR gasification process,
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lack of research on the emission characteristics of pollutants and environmental risks during the
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process.
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Co-processing of hazardous waste in industrial kilns has became one of the important
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technology development tendency in the world.15-18 Texaco gasification technology is widely
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applied to methanol and ammonia production process because of its high carbon conversion,
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efficiency and less impurity in syngas. Coal-water slurry is atomized when it is injected into the
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Texaco coal-water slurry gasifier with high purity oxygen, partial coal combustion after
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preheating, moisture evaporation and volatile combustion can soon make the gasifier temperature
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reach above 1300 ℃ in only fractions of a second, then the high temperature gasification under
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the internal reducing atmosphere will occur at the high speed rate in a few seconds.19-22 The
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gasification process which is the main reaction in the gasifier generated syngas mainly consists
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of CO, H2, CO2 and H2O, higher hydrocarbon completely decomposed with low methane content
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and no tar substance produced.23,24 Texaco gasification technology is widely applied to methanol
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and ammonia production process because of its high carbon conversion, efficiency and less
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impurity in syngas.25,26 Co-processing of CLR in Texaco coal-water slurry gasifier can realize the
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gasification of CLR meanwhile not be limited to its low melting temperature characteristic.27
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This study conducted field tests for the first time in China to research the emission
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characteristics and environmental risks of organic pollutants during co-processing of CLR in
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Texaco coal-water slurry gasifier. According to comparing the change tendency of temperature,
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pressure and syngas composition in the gasifier and analysing the toxicity equivalent
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concentration of PAHs and PCDD/Fs in all the solid waste, liquid and gas emissions under blank
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condition (without mixing CLR in the slurry) and test condition (15% CLR were mixed into the
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slurry), we can evaluate the feasibility and environmental risk during the process, would be
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thegreat technical support to the development of the co-processing technology.
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2 Materials and Methods
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2.1 Experimental materials and sampling
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Experimental materials were CLR generated by corporation B, a coal liquefaction industry
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enterprise. 48 experimental samples (Table 1) were collected under blank condition (without
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mixing CLR in the slurry) and test condition (15% CLR were mixed into the slurry). Sampling
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and analytical methods were shown in Table S1（Supporting information）.
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2.2 Field test methods
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Field tests were conducted in the Texaco coal-water slurry gasifier which can be used to
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produce 400kt/a methanol. The flow of the coal-water slurry under blank condition and test
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condition are both 55m3/h. Methanol production process diagram by Texaco coal-water slurry
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gasifier was shown in Figure 1 with sampling points marked.
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2.3 Quality control and quality assurance
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The extracts of PCDD/Fs samples were analyzed using an Agilent 6890 gas chromatograph
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coupled with an Autospec Ultima high-resolution mass spectrometer. A DB-5MS fused silica
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capillary column(60m long, 0.25mm i.d., 0.25mm film thickness) was used. The inlet
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temperature was 270℃, the carrier gas flow rate was 1mL/min, and splitless injection was used.
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The oven temperature program started at 160℃(held for 2 min), increased at 7.5℃/min to 220℃
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(held for 16min), increased at 5℃/min to 235℃(held for 7 min), then increased at 5℃/min to
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330℃(held for 1 min). The mass spectrometer was used in positive electron impact ionization
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mode. Used selected ion monitoring, and had a resolution>10000.
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Labotatory blanks were performed, and the analyte concentration in the blanks in most
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cases found lower than the detection limits or less than 10% of the concentrations in the sample.
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The limits of detection (LOD) were defined as three times the signal/noise(S/N) ratio. Each
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concentration below the LOD was replaced with 0.5*LOD when calculating total concentrations
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and total equivalent quantities (TEQs). Toxicity equivalence factors (TEFs) recommended by the
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World Health Organization (WHO) were used to calculate the TEQs.28
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The analysis of VOCs and 16 kinds of PAHs: Naphthalene (Nap), Acenaphthene (Ace),
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Acenaphthylene (Acy), Fluorene (Flu), Phenanthrene (Phe), Anthracene (Ant), Fluoranthene
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(Flua), Pyrene (Pyr), Benz[a]anthracene ( BaA ), Chrysene (Chr), Benzo[b]fluoranthene (BbF),
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Benzo[k]fluoranthene
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Dibenz[a,h]anthracene (DahA), Benzo[ghi]perylene (BghiP) were conducted using the GC-MS
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(Agilent7890A/5975C), specific chromatographic conditions were shown in Table S2
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(Supporting information). Blank recoveries of PAHs and VOCs reported in this study are ranged
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from 76.8% to 102.6%, from 82.5% to 105.3% respectively, acceptable for trace analysis of
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PAHs and VOCs as required by the standards shown in Table S1(Supporting information).
(BkF),
Benzo[a]pyrene
(BaP),
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Indeno[1,2,3-cd]pyrene
(IcdP),
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3 Results and Discussions
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3.1 Influence on the working condition of Texaco gasifier during the co-processing process
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3.1.1 Influence on syngas generation, pressure and tempreture in the gasifier
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Figure S1(Supporting information) showed the changes of syngas generation, pressure and
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temperature in the gasifier withco-process 15% CLR. Results showed that the syngas generation
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rate ranged from 176000 to 179000Nm3/h and the pressure in the gasifier reached a stable level
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of 3.71-3.74Mpa. The co-processing process has little influence on syngas generation and
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pressure.
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The comparison of the blank condition and the test condition indicates that the temperature
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under the test condition rises 5-11℃, still in the safe temperature range of the gasifier
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(1250-1350℃). Co-processing 15% CLR can make an increase of the temperature while the
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calorific value is higher than the coal,
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3.1.2 Influence on the components of syngas
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H2, CO and CO2 are the main components of the syngas, in which H2and CO are feed gas of
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methanol. Comparing the volume concentration of H2, CO and CO2 in syngas of the two
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conditions (Figure S2 Supporting information), results showed that the volume concentration of
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H2 and CO has slight increase, for H2 the volume concentration increased 0.15%, for CO
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increased 0.41%, while for CO2 declined 0.37%. The main reactions in the Texaco gasifier are as
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follows:
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CmHnSr+m/2O2=mCO+（n/2-r）H2+rH2S
（1）
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CO+H2O=H2+CO2
（2）
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（3）
C+CO2=2CO
The concentration increase of H2, CO and the decline of CO2 indicated the co-processing
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CLR process is beneficial to gas generation.
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3.2 Emission characteristics of PAHs
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3.2.1 Concentration of 16 kinds of PAHs in reactive materials
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In ordinary producing, coal-water slurry was grinded with coal, water and other activated
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coagent. In co-processing process, CLR was grinded with all other materials. Figure 2 shows
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concentration of 16 kinds of PAHs in CLR, each of them is higher than the concentration in coal.
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It can be concluded that plenty of PAHs were produced during the coal liquefaction process.29,30
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The concentrations of Pyr and BghiP were very high, the sum of the two PAHs get a percentage
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of 71.1% and 61.2% in coal and CLR respectively.
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3.2.2 PAHs concentration in gas emissions
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In the process of methanol production in Texaco coal-water slurry gasifier, there are four
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exhaust gas: high temperature black water flash steam, desulfurization flash steam,
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decarburization exhaust gas and methanol membrane separation exhaust gas. Figure 3 showed
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the concentration of 16 kinds of PAHs in the four exhaust gas. There is an increase in the high
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temperature black water flash steam and methanol membrane separation exhaust gas, increased
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35.5% and 60.9% respectively, the concentration of PAHs in desulfurization flash steam and
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decarburization exhaust gas declined 24.5% and 35.4% respectively.
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Co-processing 15% CLR can increase the concentration of PAHs in the high temperature
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black water flash steam and methanol membrane separation exhaust gas, because the PAHs
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content in the CLR is higher than in the coal, which has contribution to the increase of the PAHs
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concentration in the process of the gasification. High temperature black water flash steam was
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generated in the depressurization process, and methanol membrane separation exhaust gas was
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generated in the process of membrane separation system which can recycle hydrogen and release
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other impurity gas. For there is no other chemical change in these two process, the PAHs
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concentration increased after the co-processing process. In addition the CLR and coal can be
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decomposed into many low molecular weight alkane, olefin and alkynes under the gasification
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condition. These hydrocarbons can be decomposed into free-radicals under high temperature
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condition, then the free-radicals can be further converted to PAHs by dehydrogenation and
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recombinant, and the generated PAHs can also be transformed, therefore each component content
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would change after co-processing process.
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Desulfurization flash steam and decarburization exhaust gas are generated by the low
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temperature methanol decarburization and desulfurization process, in which methanol can absorb
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H2S, SO2 and partial PAHs. Syngas will enter the following purification process after the acid gas
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be absorbed, then the absorbent went through the CO2 stripper and H2S concentrating tower,
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desulfurization flash steam and decarburization exhaust gas generated consequently. Because of
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the technical fluctuation of leaching process during the co-processing, PAHs absorbed by
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methanol decreased, which results in PAHs concentration declined in the desulfurization flash
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steam and decarburization exhaust gas. The concentration of PAHs increased in the methanol
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membrane separation exhaust gas for more PAHs remained in the membrane separation system.
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3.2.3 PAHs concentration in liquid emissions PAHs in the liquid samples of black water in pressure filter effluent were analyzed. the
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results showed in Figure 4. We found that after co-processing 15% CLR, the PAHs concentration
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increased, while the total concentration was still low, only 37ng/L. The reason was that the PAHs
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has properties of hydrophobic-lipophilic which was more likely to be attached to organic matter
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particles.31 The liquid samples were collected after the clarification, flocculation and filter
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pressing process, therefore the adsorbing medium was lack, which made a low concentration of
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PAHs in the water.
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3.2.4 PAHs concentration in solid emissions
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Figure 5 showed the concentration of PAHs in the coarse slagof gasifier and fine slag of the
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black water disposal. After co-processing 15% CLR the concentration of PAHs both in coarse
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slag and fine slag increased, 1300µg/kg and 2300µg/kg respectively. The concentration of PAHs
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in fine slag is higher than in coarse slag under both blank condition and test condition, because
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PAHs are more liable to be adsorbed on the organic particles on solid surface. The concentration
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of PAHs both in gas and liquid emissions was low but has a significant increase in solid
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emissions. In addition, fine slag has bigger specific surface area than coarse slag, which has more
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strong adsorbing ability. Fine slag were generated after high temperature black water flash and
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subsequent processing, which had a more complete adsorption conversion between air, liquid
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and solid phases, would have a higher concentration of PAHs than coarse slag.
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3.3 Emission characteristics of PCDD/Fs
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PCDD/Fs were detected in the gas samples under the test condition. the TEQ concentration
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were shown in Figure 6 which calculated with the TEFs recommended by WHO. It was shown
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that in the high temperature black water flash steam, desulfurization flash steam and
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decarburization exhaust gas, the concentration of PCDD/Fs under the co-processing condition
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was rather low, while in the methanol membrane separation exhaust gas it was much higher. The
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cause was PCDD/Fs are more likely to form in the membrane separation process under the low
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temperature condition.
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PCDD/Fs concentration in fine slag and water under the two conditions was shown in
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Figure 7. Analysis results showed the concentration of PCDD/Fs under the co-processing
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condition was nearly to the blank condition or even lower. The concentration of PCDD/Fs in the
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fine slag and in the water are rather low, only 0.001µg/kg and 0.01ng/L respectively.
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3.4 Emission characteristics of VOCs
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Table 2 showed the VOCs concentration in gas samples, which were classified to
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halogenated hydrocarbon，benzene series and halogenated aromatics. The concentration of VOCs
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has no increase with Co-processing 15% CLR. The concentrations of VOCs are very low under
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both conditions while VOCs were not detected or below the detection limits in the liquid and
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solid samples.
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3.5 Environmental risks of the organic pollutants emission process
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The BaPeq and ΣBaPeq of PAHs are calculated by the PAHs TEF,32 and toxicity equivalent concentration of PAHs in all samples were showed in Table 3.
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After co-processing 15% CLR, the concentration of PAHs in high temperature black water
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flash steam increased significantly. And the ΣBaPeq of PAHs is 0.0106µg TEQ/m3, twice than
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that under blank condition, which exceeded the limited value 0.01µg TEQ/m3 in the Integrated
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emission standard of air pollutants in China and the Council Directive 2004/107/EC of the
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European Parliament and of the Council (relating to arsenic, cadmium, mercury, nickel and
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polycyclic aromatic hydrocarbons in ambient air),33,34 has certain environmental risks. The risk
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of PAHs can be reduced by adding exhaust gas treatment facilities such as torch system to burn
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the gas or reduce the adding ratio of CLR.
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Under the two conditions, the ΣBaPeq of desulfurization flash steam, decarburization
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exhaust gas and methanol membrane separation exhaust gas are far below the limited value
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0.01µg TEQ/m3 in the Integrated emission standard of air pollutants, so the co-processing
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process didn’t increase the PAHs emission environmental risks in these exhaust gases.
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The concentration of PAHs in the water increased after co-processing 15% CLR, however
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the ΣBaPeq is only 0.00015µg TEQ/L, far below the limited value 0.03µg TEQ/L in the
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integrated pollutant discharge standard in China and the limited value 0.1ng TEQ/L(calculated
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by the PAHs TEF) in America.35,36 The environmental risks of PAHs in the water was acceptable.
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The water can be reused to make coal-water slurry, quench in the vaporizer, or discharged after
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disposed.
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The ΣBaPeq of the coarse slag of gasifier and fine slag of the black water disposal after
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co-processing 15% CLR is 2.0235µg TEQ/kg and 5.2169µg TEQ/kg respectively, which
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increased significantly. At present, there is no relevant standard for the content of PAHs in solid
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waste in China. In Canada, the soil quality standard37 was set for the protection of environmental
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and human health, taking account of the risk of exposure of people under different use of the soil
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such as agriculture, residence, commerce and agriculture. The limitation of ΣBaPeq of the
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agriculture soil in that standard was 0.10 mg TEQ/kg, which was the most strict in that standard.
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In this study the concentration of PAHs in the coarse slag of gas furnace and fine slag of the
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black water disposal increased after co-processing CLR, whereas the total toxicity concentration
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is far less than 0.10mg TEQ/kg. So the emission discharge risk of PAHs of the coarse slag of gas
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furnace and fine slag of the black water disposal during the co-processing process is in the
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acceptable rang.
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The concentration of PCDD/Fs in liquid and solid samples and most gas samples are rather
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low both under blank condition and test condition and have low environmental risks. While
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under the test condition, the concentration of PCDD/Fs in methanol membrane separation
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exhaust gas is 0.14ng TEQ/m3 (Figure 6). Now there is no proprietary standard for the limitation
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of PCDD/Fs concentration in flue gas in co-processing of solid wastes in coal-water slurry
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gasifier, so according to the Standard for pollution control on the municipal solid waste
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incineration38 which is the most strict standard with the limit value of 0.1ng TEQ/m3 for
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PCDD/Fs emission in China, in America and EU the limited value is 0.4ng TEQ/m3 and 0.1ng
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TEQ/m3 respectively, there are certain risks and the risk of PCDD/Fs in methanol membrane
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separation exhaust gas can also be reduced by adding exhaust gas treatment facilities such as
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torch system to burn the gas or reduce the adding ratio of CLR.
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The concentration of VOCs in gas emission were far below the blank condition under test
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condition, in the liquid emission and solid waste were mostly not detected or below the detection
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limits, so VOCs emission in the co-processing process has low environmental risk.
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4 Conclusions
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During the co-processing of 15% CLR in Texaco coal-water slurry gasifier process, there
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had little impact on the pressure and syngas output of the gasifier, but made an increase of 5-11℃
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of the temperature and promoted the formation of H2 and CO. The concentration of PAHs in part
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of the gas emission and liquid emission increased a little in the co-processing process, but the
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toxicity equivalent concentration was still far lower than the standard limitation, has low
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environmental risk. The concentration of PAHs in solid wastes increased significantly in the
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co-processing process, but the total toxicity equivalent concentration was also low, the
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environmental risk was in the acceptable range. The emission of PCDD/Fs and VOCs during the
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co-processing process has low environmental risk. Organic matters were relatively fully
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degraded during co-processing of CLR in Texaco coal-water slurry gasifier, which would be a
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new way to dispose certain kinds of solid waste in practice.
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Author Information
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Corresponding Author
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*Phone: +86-10-84915182; fax: +86-10-84913903; e-mail:
[email protected]; address: Research
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Institute of Soil and Solid Waste Management, Chinese Research Academy of Environmental
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Sciences, No.8, Dayangfang, Anwai, Chaoyang district, Beijing 100012, China.
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Notes
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The authors declare no competing financial interest.
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Acknowledgements
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This research supported by the State Key Laboratory of Environmental Criteria and Risk
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397 398
Figure 1. Methanol production process diagram by Texaco coal-water slurry gasifier
399 400
45 PAHs in CLR
PAHs in coal
35
300
30 250 25 200 20 150 15 100
10
50
5 0
0 Nap Ace Acy
400 401
Flu
Phe
Ant Flua Pyr BaA Chr BbF BkF BaP IcdP DahABghiP PAHs
Figure 2. Concentration of 16 kinds of PAHs in reactive materials
402
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PAHs concentration in coal(mg/kg)
40
350 PAHs concentration in CLR(mg/kg)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
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5
Nap Ace Acy Flu Phe Ant Flua Pyr BaA Chr BbF BkF BaP IcdP DahA BghiP
PAHs concentration(µg/m3)
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 avrblkS1 avrS1 avrblkS2 avrS2 avrblkS3 avrS3 avrblkS4 avrS4 number of samples
403 404
Figure 3. PAHs concentration in gas emissions
405 40
Nap Ace Acy Flu Phe Ant Flua Pyr BaA Chr BbF BkF BaP IcdP DahA BghiP
35 PAHs concentration(ng/L)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
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30 25 20 15 10 5 0 avrblkS5
406 407
avrS5 number of samples
Figure 4. PAHs concentration in liquid emissions
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4500
Nap Ace Acy Flu Phe Ant Flua Pyr BaA Chr BbF BkF BaP IcdP DahA BghiP
PAHs concentration(µg/kg)
4000 3500 3000 2500 2000 1500 1000 500 0 avrblkS6
408 409
avrS6 avrblkS7 number of samples
avrS7
Figure 5. PAHs concentration in solid emissions
410 0.16 PCDD/Fs concentration(ng TEQ/m3)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
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0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 S1
S2
S3 number of samples
S4
411 412
Figure 6. PCDD/Fs concentration in gas emissions under test condition
413
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2,3,7,8-T4CDD 1,2,3,7,8-P5CDD 1,2,3,4,7,8-H6CDD 1,2,3,6,7,8-H6CDD 1,2,3,7,8,9-H6CDD 1,2,3,4,6,7,8-H7CDD OCDD 2,3,7,8-T4CDF 1,2,3,7,8-P5CDF 2,3,4,7,8-P5CDF 1,2,3,4,7,8-H6CDF 1,2,3,6,7,8-H6CDF 1,2,3,7,8,9-H6CDF 2,3,4,6,7,8-H6CDF 1,2,3,4,6,7,8-H7CDF 1,2,3,4,7,8,9-H7CDF OCDF
0.0015
PCDD/Fs concentration(ng TEQ/L)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
PCDD/Fs concentration(µg TEQ/kg)
Page 23 of 25
a 0.001
0.0005
0 blkS5 S5 number of samples
417
2,3,7,8-T4CDD 1,2,3,7,8-P5CDD 1,2,3,4,7,8-H6CDD 1,2,3,6,7,8-H6CDD 1,2,3,7,8,9-H6CDD 1,2,3,4,6,7,8-H7CDD OCDD 2,3,7,8-T4CDF 1,2,3,7,8-P5CDF 2,3,4,7,8-P5CDF 1,2,3,4,7,8-H6CDF 1,2,3,6,7,8-H6CDF 1,2,3,7,8,9-H6CDF 2,3,4,6,7,8-H6CDF 1,2,3,4,6,7,8-H7CDF 1,2,3,4,7,8,9-H7CDF OCDF
b 0.01
0.005
0 blkS7 S7 number of samples
414 415 416
0.015
Figure 7. PCDD/Fs concentration in solid and liquid emissions
Table 1. Field test samples
Number of Samples
Sampling points
Frequency ①
samples ②
S1 High temperature black water flash steam
Flashing tower exhaust port
3
S1test1-3
S2Desulfurization flash steam
Desulfurizing tower exhaust port
5
S2test1-5
S3Decarburization exhaust gas
Decarburization tower exhaust port
5
S3test1-5
S4Methanol membrane separation exhaust gas
Rectifying tower exhaust port
5
S4test1-5
S5Water
Delivery tank
2
S5test1-2
S6Coarse slag
Slag-dripping port
2
S6test1-2
S7Fine slag
Pressure filter port
2
S7test1-2
418
①:blk means samples under blank condition, avr means average value of each kind of sample
419
②:Sampling points in Figure1
420 421
Table 2. VOCs concentration in gas samples
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Gas samples Halogenated hydrocarbon (mg/m3)
Page 24 of 25
Blank condition
Test condition
2.8±1.5
1.4±1.6
15.9±1.1
16.9±0.7
0.004
ND
8.4±4.2
11.3±5.4
6.7±0.82
8.1±1.0
0.004
N.D.
1.6±0.39
0.25±0.083
1.8±0.15
2.1±0.12
0.0082±0.0082
N.D.
N.D.
N.D.
0.85±0.16
0.82±0.064
N.D.
0.004
High temperature black water flash Benzene series (mg/m3) steam Halogenated aromatics (mg/m3) Halogenated hydrocarbon (mg/m3) Benzene series(mg/m3)
Desulfurization flash steam
Halogenated aromatics (mg/m3) Halogenated hydrocarbon (mg/m3) Benzene series(mg/m3)
Decarburization exhaust gas
Halogenated aromatics (mg/m3) Halogenated hydrocarbon (mg/m3) Methanol membrane separation Benzene series(mg/m3) exhaust gas Halogenated aromatics (mg/m3)
422 423
Table 3. Toxicity equivalent concentration of PAHs in all samples Samples
Blank condtion ΣBaPeq
Test condition ΣBaPeq
High temperature black water flash steam S1(µg/m3)
0.0045±0.0008
0.0106±0.0039
Desulfurization flash steam S2(µg/m3)
0.0100±0.0049
0.0091±0.0061
Decarburization exhaust gas S3(µg/m3)
0.0081±0.0079
0.0034±0.0011
Methanol membrane separation exhaust gas S4(µg/m3)
0.0044±0.0027
0.0046±0.0016
0.1460±0.0063
0.1676±0.0114
1.3850±0.1339
2.0235±0.0695
Water S5(ng/L)
Coarse slag S6(µg/kg)
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Fine slag S7(µg/kg)
3.3602±0.1346
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5.2169±0.4748
