Investigation of coal and sludge co-combustion process in a small fixed bed furnace

In practice, there are many methods of sludge utilization. One of them is incineration. Fuel mixtures with not large addition of sludge may be burnt in existing fixed bed appliances originally designed for coal. The paper describes results of experiments of co-combustion of coal with sludge. Seven kinds of mixtures have been investigated: coal itself and six mixtures containing 5, 10, 15,20,25 and 30 percent of sludge. The process has been carried out in a small solid grate furnace covered with additional heat insulation material. In a real boiler fuel travels over the grate through different airflow zones. In experimental installation this process was simulated by changing air stream, which was blown under the grate in a furnace. Temperatures in four points in a furnace chamber, concentration of CO2, 02, S02, NOx, CO in exhaust gas and burning fraction in slag have been measured. The paper presents results from laboratory installation as well as results from similar research carried out in a real boiler.