Characteristics of PM and PAHs emitted from a coal-fired boiler and the efficiencies of its air pollution control devices

Figures & data

Figure 1. Sampling points of the coal-fired boiler

Figure 2. Sampling train of (a) FPM_2.5 and CPM (US EPA method 202 A), and (b) PAHs (U.S. EPA method 23A)

Table 1. Concentration of gaseous pollutants measured at various sampling locations

Unit	Coal-fired boiler
Location	SCR inlet	SCR outlet	WESP inlet	Stack
H2O (%)	-	8 ± 0.47	13 ± 0.39	13 ± 1.39
O2 (%)	2.9 ± 0.02	3.8 ± 0.21	6.3 ± 0.30	6.5. ± 0.30
CO (ppm)	6.6 ± 0.71	5.7 ± 0.41	5.9 ± 0.28	4.8 ± 0.61
CO2 (%)	15.8 ± 0.16	15.3 ± 0.21	13.2 ± 0.25	13.0 ± 0.07
NOx (ppm)	108 ± 3.39	57 ± 0.57	56 ± 3.76	56 ± 2.17
SO2 (ppm)	323 ± 4.59	284 ± 19.2	< 1	< 1
HCl (ppm)	-	16.8 ± 0.34	< 1	< 1
NH3 (ppm)	-	-	-	< 1

-: No sampling

Figure 3. Concentrations of FPM measured at three sampling locations

Figure 4. Concentrations of FPM, FPM_2.5 and CPM measured at the stack

Figure 5. Compositions of CPM emitted from coal-fired boiler

Table 2. Gas-phase and solid-phase PAHs measured at two sampling locations of the coal-fired boiler investigated (ng/Nm³)

Species	WESP inlet			Stack
	Gas phase	Solid phase	Total	Gas phase	Solid phase	Total
Naphthalene (Nap)	383	9.27	392	271	13.5	285
2-Methylnaphthalene (2-MN)	1.25	6.55	7.81	0.46	1.71	2.17
Acenaphthylene (AcPy)	3.80	4.39	8.20	3.57	1.27	4.84
Acenaphthene (Acp)	0.42	1.25	1.66	0.06	0.10	0.16
Fluorene (Flu)	ND	3.69	3.69	ND	ND	0.00
Phenanthrene (PA)	14.1	7.54	21.6	23.7	5.21	28.9
Anthracene (Ant)	2.55	1.02	3.57	4.79	1.07	5.86
Floranthene (FL)	20.9	13.2	34.1	53.7	7.01	60.8
Pyrene (Pyr)	39.9	29.2	69.2	72.6	10.2	82.8
Benzo[c]fluorene (BcFE)	0.24	1.17	1.40	0.88	0.20	1.08
Cyclopenta[cd]pyrene (CYC)	0.11	0.45	0.57	1.78	0.04	1.82
Benzo(a)anthracene (BaA)	2.52	1.89	4.41	1.57	0.85	2.42
Chrysene (CHR)	7.25	3.78	11.0	22.4	2.92	25.3
5-Methylchrysene (5-MC)	0.27	0.07	0.33	0.25	0.08	0.33
Benzo(b)fluoranthene (BbF)	2.58	2.18	4.77	9.39	1.41	10.8
Benzo(k)fluoranthene (BkF)	1.11	1.19	2.30	4.25	0.84	5.09
Benzo[j]fluoranthene (BjF)	1.23	1.02	2.25	4.68	0.66	5.34
Benzo[e]pyrene (BeP)	15.7	10.7	26.4	8.83	2.40	11.2
Benzo(a)pyrene (BaP)	3.87	2.83	6.70	1.32	0.39	1.71
Perylene (PER)	0.30	0.32	0.62	0.24	0.07	0.30
Ideno[123-cd]pyrene (IND)	4.26	3.46	7.72	2.67	0.89	3.56
Dibenz(ah)anthracene (DBA)	0.34	0.10	0.44	0.14	0.03	0.17
Benzo[ghi]perylene (BghiP)	34.8	21.8	56.6	5.69	1.93	7.62
Dibenzo[al]pyrene (DBalP)	ND	ND	ND	ND	ND	ND
Dibenzo(ae)pyrene (DBP)	ND	ND	ND	ND	ND	ND
Dibenzo(ai)pyrene (DBaiP)	ND	ND	ND	ND	ND	ND
Dibenzo(ah)pyrene (DBahP)	ND	ND	ND	ND	ND	ND
Total PAHs	540	127	667	494	52.8	547

ND< indicate the concentration is less than the MDL

Figure 6. Distribution of PAHs between gas and solid-phases at two sampling locations

Figure 7. Mass fractions of different ring PAHs at two sampling locations

Figure 8. TEQ distribution of 27 PAHs at two sampling locations

Table 3. Emission factors of various pollutants (g/ton of coal) from coal-fired boilers

Ref	APCDs	FPM	FPM2.5	CPM	PAHs	NOx	SOx
This study	SCR+ESP+WFGD+WESP	11	1.09	581	0.007 (27 PAHs)	912	0.04
Wu et al. (2020)	SCR+ESP/FF+WFGD+WESP			74–168
US EPA. (2019)	-			260–520
Chen et al. (2019)	SCR+ESP+WFGD	40				360	100
Chen et al. (2019)	SCR+LLT-ESP+WFGD		4.09 –5.39
Ruan et al. (2019a)	FF+WFGD+WESP		28
Wu et al. (2018)	FF+WFGD+WESP	81	9
Wu et al. (2018)	ESP+WFGD+WESP	130	18
Wang et al. (2018)	Limestone and urea injection+FF				3.53 (16 PAHs)
Hsu et al. (2016)	SCR+ESP+FGD				0.002 (16 PAHs)

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