| Liquid sulphur produced from Clause Plants usually contains 150∼350ppmm of dissolved H2S and H2Sx. It should be degassed to a level of 10ppmm or lower before it is handled for the protection of the environment and the safety of the workers. A technology is being developed to remove H2S in liquid sulphur by using bubbles to enhance the interfacial mass transfer. A theoretical model of bubble degassing was analyzed and validated by conducting laboratory experiment, which was the test of O 2 removal from water by using N2 bubbles. Several micro-bubble generators have been tested in the laboratory, including a porous tube bubble generator and cavitations tube generators. A series of data was obtained to study the de-O2 efficiency under varied conditions of gas amount and bubble size. It was obtained that the best efficiency of de-O2 only by agitation was about 85%; the best efficiency by only injecting bubbles was about 82%. By combining both injected N2 bubbles and agitation, the efficiency could reach 92%. Additionally, the de-O2 efficiency increased with the decrease of bubble size because the smaller the bubble size, the higher the gas-liquid contact area. Sometimes, the smaller bubble size also meant a lower degree of turbulence. It might meanwhile also decrease the mass transfer coefficient. After laboratory testing, a series of H 2S degassing from sulphur by air bubbles was conducted in the field. The best de-H2S efficiency was 66% when only by agitation at 760rpm; 64% when only by air injection at 175 SCFH; 86% efficiency was obtained when combining 760rpm agitation and 125 SCFH air injections. By two reactors in series, the de-H2S efficiency could reach 97%. |
