STUDIEKSPERIMENTAL PENGARUH KETEBALAN (DEPTH) udDARI TIP NOZZLE DAN TEKANAN UDARA PADA TIPE udAIR-ASSISTED NOZZLEUNTUK SISTEM ATOMISASI udCAMPURAN BATUBARA SERBUK-AIR ud(COAL-WATER MIXTURE (CWM))

摘要

The aim of the experimental study of atomization system for coal-water mixture ud(CWM)is to research, analyze and discussed the effects from the depths of the tip nozzle udand air pressures toward atomization results of CWM that used air-assisted nozzle for udcold testing.udThe Materials used in this study is a mixture of coal powder size 112.5 µm(mesh ud150)and fresh water added with some additives. The composition ofthe mixture in% udmass consists of, coal powder 40% and 60% fresh water with the addition of additives udCMC (Carboxyl MethylCellulose)at 3% of the weight of coal. Atomiser (nozzle)wereudused that type of water-assisted with 3 variations in thickness (depth)of the nozzle tip,udwhich is 1.5 mm, 3mm and 4.5 mm. Tests conducted on the atomization CWM with udCWM constant pressure 2.8 bar and with variations in air pressure 2 bar, 2.4 bar and ud2.8 bar.udThe results showed that determining the optimum composition of CWM has a udstrong influence in the atomization CWM. Fromthis research it is known that the air udpressure of 2 bar and constantpressure ofCWM, the use ofnozzles with a thickness of ud1.5 mm nozzle tip produces air flow of 0.000611 m3 / s and debit CWM registration ud0.0000248 m3 / s while the thickness of the nozzle tip 4.5 mm produces air flow of ud0.000617 m3 / s and debit CWM registration 0.0000323 m3 / s. And an increase in airudpressure ateach nozzle tip thicknessvariation produces air flow value and debit CWM udincreasing, so the ratio of air / CWM also increased, thereby increasing aerodynamic udforces that worked great. By variation ofthe greatest air pressure (2.8 bar)and the udthickness of the greatest tipnozzles (4.5 mm)is the largest value of its ALR-0051 is 30 ud620 with a spray angle. With the increasing value of ALR, the atomization is formed udmore and more, this means fine droplets thatform are also more and more, in otherudwords the smaller the SMD so that the quality of atomization increases. At CWM udflowing air and at the end of the nozzle (nozzle tip)is less guided, mixing between air udand CWM become weak. This causes the ligament that forms less able to spread. Butudwhen air and guided CWM more, mixing becomes stronger, so that the ligaments which udcan produce more scattered and atomization of CWM for the better. And from this udresearch may also note that the air pressure to improve the quality of atomization.udKeywords: Coal-Water Mixture (CWM), droplets, atomization, coal powder, air udassisted nozzle, Carboxyl Methyl Cellulose (CMC)