Abstract

The research is intentionally aimed to employ the multiple-phase nozzles to produce the 10-micrometer water droplets in gas form to remove less 100-micrometer smaller dust particles by agglomeration process inside street tunnel on heavy traffic point sources at sky train MRT-BTS Saphan Khwai station in Bangkok. The four sets of 100-m hoses with 52 multiple-phase nozzles (208 nozzles) were established on 100-m beams (four beams), which are 21-m wide (5-m apart) and 5.575-m high, and connecting with high pressure pump (1,000 lbs/min) to press clean water 0.076 liters/min through the 10-micrometer orifice nozzles. The spraying time was about every 10 minutes during collecting TSP and PM10 dust by Hi-Volume Air Sampler on five periods of 05:00-08:00, 08:00-11:00, 11:00-14:00, 14:00-17:00, and 17:00-20:00 for 5-consecutive days, 30 November to 4 December 2008. Also, the air temperature, actual vapor pressure, and speed-direction wind measured at 1.5 and 5.0 meters in height underneath of the ceiling and above the roof of MRT-BTS Saphan Khwai station. Results found that the multiple-phase nozzles showed effectiveness to remove the smaller 100-micrometer dust particles underneath of MRT-BTS Saphan Khwai station by spraying 10-micrometer water droplets through 10-micrometer orifice nozzles. The decreasing concentration of TSP northerly 30.25 %, southerly 26.21 %; and also for PM10 northerly 39.96 %, southerly 40.39 %. Moreover, the concentration between street tunnel and northerly were decreased in both TSP (30.38%) and PM10 (40.17 %), and southerly were decreased in both TSP (30.05%) and PM10 (40.88 %). In case, on the central line effects between street tunnel and northerly found the decreases of TSP (30.64%) and PM10 (37.65%), southerly decreases of TSP (33.71%) and PM10 (43.78%). An increase of the 10-micrometer water droplets spraying frequency through multiple-phase nozzles (208 nozzles) is expected to gain more decreasing concentration down to under standard values. In addition, an applying the concentration of smaller 100-micrometer dust particles is useful for setting the automatic pumping operation that would be acceptable to the public.

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