PMC:4534144 / 9308-13089
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/4534144","sourcedb":"PMC","sourceid":"4534144","source_url":"https://www.ncbi.nlm.nih.gov/pmc/4534144","text":"Results and discussion\nFigure 2a shows the motion path of emissions in the studied incinerator. As expected, due to the lack of baffles, incinerator geometry as well as the tangential flow of emissions, large rotating bubbles are formed in the incinerator. Rotating regions (eddies) are formed when the flow pressure reduces the kinetic energy of the fluid particles causing stagnant points in the flow. In addition, there is also a secondary flow that directs the flow downward [25]. Fig. 2b shows the iso-velocity contours in the initial state (without baffles). As seen, increasing the inlet gas temperature will increase the velocity (compared to the isothermal case). A maximum velocity of 55 m/s occurs in the incinerator outlet. In this case, the high speed gas particles quickly leave the incinerator causing a decrease in the residence time. In this case, the average residence time of gaseous emissions is 3 s.\nFig. 2 a The motion path of gases in the incinerator in normal conditions, (b) Iso-velocity contours in the incinerator in normal conditions\nFigure 3 shows the predicted temperatures. Temperature increases after the gaseous emissions entering the lower part of the studied incinerator. The temperature inside the studied incinerator reaches over 1300 °C. The predicted temperatures demonstrate cold zones in the incinerator where air is mixed with gas eddies and thus temperature decreases to 600 °C. The temperature drop in the incinerator may significantly affect the composition of the exhaust gases from the incinerator preventing the removal of PCB bonds.\nFig. 3 The temperature profile (°C) inside the incinerator in normal condition\n\nEfficiency Optimization\nBaffles were embedded in the incinerator to remove large rotating currents (or eddy). In the first case, two baffles each with an angle of 90° were installed on the height of 3 and 5 m from the bottom of the studied incinerator. Fig. 4a, shows the two-dimensional motion of particles in this case. The baffles were made of steel as the studied incinerator body. Unlike the previous case, the motion path is divided into several parts. Removal of large eddies and the sudden displacements of gaseous emissions increase the residence time and thereby optimal air mixing. The residence time calculated for this case is 3.3 s. Fig. 4b, shows the temperature profile. The maximum temperature in this case was 1400 °C. Although the heat concentration can be observed in the middle of the studied incinerator, the temperature profile is not significantly different with the previous case.\nFig. 4 a The schematic motion path of gases in the incinerator for the Case 1, (b) The temperature profile (°C) inside the incinerator for the Case 1\nIn the second case, 3 baffles were installed on the height of 2, 4 and 8 m from the bottom of the studied incinerator with an angle of 90 °. Fig. 5a, shows the gas motion path in this case. As shown, the large volume of the incoming gas is located adjacent to the heat source. The gas emission leaves the incinerator with a lower speed across a longer path compared to the previous case. In this case, the turbulent flow in the incinerator is stronger than the previous case. The average residence time is 3.5 s. The temperature profile is shown in Fig. 5b, Little changes in the temperature profile are observed. Like the previous case, the heat concentration is observed in the middle of the incinerator. The maximum temperature in this case is 100 °C higher than the previous case. Other studies have shown that longer path incinerator or multiple chamber incinerator can be increased PCB removal rate [15, 26].\nFig. 5 a Schematic motion path of gases in the incinerator for the Case 2, (b) The temperature profile (°C) inside the incinerator for the case 2","divisions":[{"label":"title","span":{"begin":0,"end":22}},{"label":"p","span":{"begin":23,"end":1062}},{"label":"figure","span":{"begin":921,"end":1062}},{"label":"label","span":{"begin":921,"end":927}},{"label":"caption","span":{"begin":928,"end":1062}},{"label":"p","span":{"begin":928,"end":1062}},{"label":"p","span":{"begin":1063,"end":1661}},{"label":"figure","span":{"begin":1583,"end":1661}},{"label":"label","span":{"begin":1583,"end":1589}},{"label":"caption","span":{"begin":1590,"end":1661}},{"label":"p","span":{"begin":1590,"end":1661}},{"label":"title","span":{"begin":1663,"end":1686}},{"label":"p","span":{"begin":1687,"end":2719}},{"label":"figure","span":{"begin":2569,"end":2719}},{"label":"label","span":{"begin":2569,"end":2575}},{"label":"caption","span":{"begin":2576,"end":2719}},{"label":"p","span":{"begin":2576,"end":2719}},{"label":"label","span":{"begin":3635,"end":3641}}],"tracks":[{"project":"TEST0","denotations":[{"id":"26269746-121-127-1455814","span":{"begin":3626,"end":3628},"obj":"[\"17134732\"]"}],"attributes":[{"subj":"26269746-121-127-1455814","pred":"source","obj":"TEST0"}]},{"project":"2_test","denotations":[{"id":"26269746-17134732-59012432","span":{"begin":3626,"end":3628},"obj":"17134732"}],"attributes":[{"subj":"26269746-17134732-59012432","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"TEST0","color":"#93d7ec","default":true},{"id":"2_test","color":"#ece793"}]}]}}