Using pollution roses to assess sulfur dioxide impacts in a township downwind of a petrochemical complex

Figures & data

Figure 1. GIS map of the No. 6 Naphtha Cracking Complex, its major SO_x emission sources and affected areas, and the downwind direction with a wind rose diagram from the Taishi air quality monitoring station from 1995 to 2009.

Table 1. Major SO₂ emissions from manufacturing plants of the No. 6 Naphtha Cracking Complex in Taiwan in 2009

Plant	Major Products	Capacity (10,000 Tons Per Year)	No. of Plants	No. of Stacks	Stack Height (m)	Stack Diameter (m)	Stack Exit Gas Temperature (°C)	Stack Exit Gas Velocity (m/sec)	SO2 Emissions
									Tons/Year	Percentage
Cogeneration plants	Electricity, steam, pure water	2820 MW	3	6	250	6.2	30	13.8	2549	41.0%
				3	150	2.6	55	14.9
				5	150	3.3	52	17.7
Coal power plant	Electricity	1800 MW	1	3	250	6.2	33	12.6	1803	29.0%
Oil refinery plants	Naphtha, LPG^a	2500	3	40	40–150	2.0–4.6	61–227	5.2–15.2	654	10.5%
	Gasoline, diesel, kerosene
Aromatics and plastics plants	Xylene, benzene, styrene, phenol, toluene	230/128/120/40/2	12	73	30–57	1.0–2.9	52–277	4.8–13.9	493	7.9%
	PTA, PP, PS, ABS, PBT, PC^a	220/51/41/32/20 MT
Naphtha cracking plants	Ethylene, propylene, 1,3-budiene	293.5/236.7/44.7	3	55	30–40	0.8–1.2	60–241	6.0–12.2	403	6.5%
Other downstream plants	Petrochemicals and raw plastics^b	752	42	196	20–37	0.8–2.3	41–256	2.8–9.7	314	5.1%
Total			64	381					6217	100.0%
Notes: ^aLPG = liquefied petroleum gas; PTA = purified terphthalic acid; PP = polypropylene; ABS = acrylonitrile butadiene styrene; PBT = polybutylene terephthalate; PC = polycarbonate. ^bMajor petrochemicals and raw plastics include vinyl chloride monomer, polyvinyl chloride, ethylene vinyl acetate, carbon fiber, acrylonitrile, polyethylene, methyl methacrylate, ethylene glycol, bis(2-ethylhexyl)phthalate, epoxy, propionic anhydride, isooctanol, bisphenol A, ethylene glycol, 1,4-butylene glycol, and isononyl alcohol.

Table 2. Summary statistics for hourly SO₂ concentrations (ppb) at the Taishi air quality monitoring station from 1995 to 2009

Year	No. Hours Per Year	Mean	SD	Maximum	Annual Average 99th Percentile^a	Three-Year Average 99th Percentile^b	No. of SO2 Measurements >75 ppb^c
1995	8536	3.6	5.2	61.4	54.9	—	0
1996	8410	3.1	5.3	74.2	48.9	—	0
1997	8437	3.4	5.7	70.3	60.5	54.8	0
1998	8357	3.1	5.0	59.7	48.0	52.5	0
1999	8393	2.4	3.5	39.8	36.7	48.4	0
2000	8450	2.2	2.8	36.9	32.9	39.2	0
2001	8536	3.1	6.3	143.7	79.3	49.6	6
2002	8526	3.1	6.2	137.5	90.7	67.6	10
2003	8433	3.4	7.2	110.0	87.3	85.8	13
2004	8045	3.4	6.9	118.1	106.4	94.8	15
2005	8346	5.2	12.0	335.6	201.7	131.8	61
2006	8607	4.1	6.1	151.6	103.8	137.3	10
2007	8576	4.5	5.4	103.8	74.2	126.6	4
2008	8470	5.1	8.6	180.3	143.5	107.2	23
2009	8553	4.4	5.9	134.1	86.2	101.3	11
Notes: ^aThe annual 99th percentile (fourth highest daily maximum hourly value) of 1-hr daily maximum concentrations. ^bThe 3-yr average of the annual 99th percentile of 1-hr daily maximum concentrations. ^cEPA new standard is 75 ppb based on the 3-yr average of the 99th percentile concentration of the daily 1-hr maximum concentrations.

Figure 2. The 99th percentile 3-yr average SO₂ concentration and 3-yr moving average SO_x emissions at the Taishi air quality monitoring station from 1995 to 2009.

Figure 3. SO₂ pollution roses of averages (a, b, c) and percentiles (d, e, f) at the Taishi air quality monitoring station from 1995 to 2009.

Figure 4. Wind-speed-specific SO₂ concentrations (mean + SD) during emission-affecting periods (downwind) from the petrochemical complex and traffic emission-affecting periods (land-wind) and nonaffecting periods (sea-wind) at the Taishi air quality monitoring station from 1995 to 2009. (a) 1995–1999, (b) 2000–2004, and (c) 2005–2009.

Figure 5. Diurnal SO₂ concentrations during emission-affecting periods (downwind) from the petrochemical complex and traffic-affecting periods (land-wind) and nonaffecting periods (sea-wind) at the Taishi air quality monitoring station from 1995 to 2009. (a) 1995–1999, (b) 2000–2004, and (c) 2005–2009.