Incinerators for Alkaline Solutions
By incineration of alkaline solutions, low-melting eutectics are formed which always lead to an attack of the refractory lining of the combustion chamber. In order to avoid total wear of the initial ceramic lining a jacketed combustion chamber is used. The heat loss through the chamber is utilised to generate saturated steam. By this, the refractory lining is cooled and damaged parts of it will be replaced by solidified melt.The alkaline solution, which is spray-injected into the combustion chamber as an aqueous solution, leaves the combustion chamber mainly as melt flowing off the surface of the combustion chamber, whilst the smaller part is carried off in the flue gas. In a quench underneath the combustion chamber, the flue gases are cooled and scrubbed in direct contact with water and the now purified alkaline solution is dissolved in water. A small part of it, however, remains as aerosol in the flue gas and has to be removed by using an aerosol separation system.
As the heat loss via the cooled surface of the combustion chamber is huge, a main task for designing such a unit is to minimise the size of it. A common way is to use pure oxygen or enriched air for oxidising the organics instead of ambient air. As in this case much less nitrogen is contained in the flue gas, the combustion chamber can be designed much smaller at the same residence time.