Characterization of polycyclic aromatic hydrocarbons in fugitive PM10 emissions from an integrated iron and steel plant.

Fugitive emissions of PM10 (particles <10µm in diameter) and associated polycyclic aromatic hydrocarbons (PAHs) were monitored in the vicinity of coking unit, sintering unit, blast furnace and steel manufacturing unit in an integrated iron and steel plant situated in India. Concentrations of PM10, PM10-bound total PAHs, benzo (a) pyrene, carcinogenic PAHs and combustion PAHs were found to be highest around the sintering unit. Concentrations of 3-ring and 4-ring PAHs were recorded to be highest in the coking unit whereas 5-and 6-ring PAHs were found to be highest in other units. The following indicatory PAHs were identified: indeno (1,2,3-cd) pyrene, dibenzo (a,h) anthracene, benzo (k) fluoranthene in blast furnace unit; indeno (1,2,3-cd) pyrene, dibenzo (a,h) anthracene, chrysene in sintering unit; Anthracene, fluoranthene, chrysene in coking unit and acenaphthene, fluoranthene, fluorene in steel making unit. Total-BaP-TEQ (Total BaP toxic equivalent quotient) and BaP-MEQ (Total BaP mutagenic equivalent quotient) concentration levels ranged from 2.4 to 231.7ng/m(3) and 1.9 to 175.8ng/m(3), respectively. BaP and DbA (dibenzo (a,h) anthracene) contribution to total-BaP-TEQ was found to be the highest.

Influence of burning of fireworks on particle size distribution of PM10 and associated barium at Nagpur.

Influence of burning of fireworks on particle size distribution of PM(10) and associated barium (Ba) were studied at a congested residential cum commercial area of Nagpur city, India. Sampling was carried out by cascade impactor having 50% cut-off aerodynamic diameters of <10, 9, 5.8, 4.7, 3.3, 2.1, 1.1, 0.7, and <0.4 µm, 2 days before diwali, during diwali, celebrations of marriage functions, and New Year's Eve. Noticeably, increased levels of PM(10) and Ba were observed during diwali as compared to days before diwali and other activities. PM(10) levels were increased by four to nine times whereas Ba levels were increased by eight to 20 times higher in alveolar region, when compared with the levels observed before diwali. Probability of deposition of Ba mass in alveolar region varied between 14 and 27 ng/h with higher deposition when the burning of fireworks activity was lower near the site. Trimodal distribution of Ba was observed on the first 2 days of diwali at 0.4-2.1, 2.1-4.7, and 4.7 to less than PM(10) micrometer range. While on the third day, it appeared bimodal with 70% contribution in coarse fraction whereas on the fourth day, distribution appeared unimodal with 66% contribution in alveolar region (<0.4-1.1 µm). Distribution of Ba varied with respect to particle size, in accordance with the intensity of the fireworks used on different days and distance between the burning of firecrackers from the monitoring site.

Cyclone as a precleaner to ESP--a need for Indian coal based thermal power plants.

Almost all coal based thermal power plants (CTPP) in India use electrostatic precipitator (ESP) for reduction of particulate matter (PM) in flue gas generated due to the combustion of Indian coal. This coal is characterized by high ash content, low calorific value and low sulfur content resulting in the generation of a very large amount of highly electrically-resistive fly-ash; thereby requiring a very large size ESP to minimize the fly-ash emissions. However, the flue-gas particle size distribution analysis showed that 60% of the particles are above 15 microm size, which can be conveniently removed using a low-cost inertial separator such as a cyclone separator. It is proposed that a cyclone be used, as a pre-cleaner to ESP so that the large size fraction of fly-ash can be removed in the pre-cleaning and the remaining flue-gas entering the ESP will then contain only small size particles with low dust loading, thereby requiring a small ESP, and improving overall efficiency of dust removal. A low efficiency (65%), high throughput cyclone is considered for pre-cleaning flue gas and the ESP is designed for removal of the remaining 35% fly-ash from the flue gas. It is observed that with 100% dust load, the ESP requires six fields per pass, whereas with cyclone as a pre-cleaner, it requires only five fields per pass. Introducing cyclone into the flue gas path results in additional head loss, which needs to be overcome by providing additional power to induced draft (ID) fan. The permissible head loss due to the cyclone is estimated by comparing the power requirement in the bag filter control unit and cyclone-ESP combined unit. It is estimated that a head loss of 10 cm of water can be permitted across the cyclone so as to design the same for 65% efficiency.