POTENTIAL SULFUR CONCENTRATION REDUCTION IN CLINKER BURNING PROCESSES

Process operation and productivity of the clinker production kiln is a very complex process and it is very important to emphasize that this depends on many different factors. The impact of these factors in the process is variable and depends mainly on the process conditions, process parameters, raw material, fuel etc. In this article will be introduced the impact of sulphur in the process and possible methods of sulphur concentration reduction in raw material and fuel preparation, as well as during the process. Test result of desulphurization processes of the alternative fuel will be given. In this project it is used a wildfire with high sulphur content which will also be explained below, and which affects directly the efficiency and productivity of the clinker production line. Sulphur has individual impact in the process, and not only. It has negative affects when it is combined with other volatile ingredients. For this reason, we will refer to the other volatile materials as well, such as alkali and chlorine. Recirculation phenomenon is related to volatile ingredients. Recycling of volatile components is related to the fact that, with the increase of temperature, components such as alkalis, sulphur and chlorine, they are released by thermal decomposition of the substances in which they are part of. Together with the hot gases of the kiln, they move backward into areas with lower temperatures in pre-heater sections. When they arrive at sites which have lower temperature than their condensation temperature, they will be condensed and deposited as salts in the relevant section of the system walls. Mentioned ingredients are deposited also in fresh raw materials entering the system and in some cases, entering into reactions with the last one. This way, a certain part of the volatile components go back in the areas with high temperatures in the kiln process. The mentioned process, starts again from the beginning. This phenomenon is known as internal reflows. In such cases, only a limited part of the volatile components can be removed and discharged from the kiln with clinker and the remaining part, is being recycled into the system. Only a small part of them is discharged through stack gases in the closed system. Alkaline ingredients such as chlorine and sulphur enter the clinker production system by raw materials and fuel used in the process. Sulphur-load in the cement kilns production system usually grows by the use of alternative fuels, particularly coke or bituminous sand in our case.