Air control During the last 15 years many different approaches connecting the primary- with the secondary-air in order to influence the O2 concentration, the steam production and the fire position were tested. Some brought good results, others did not - depending on the type of boiler (center flow or parallel flow). For each type of boiler a characteristic optimum of air control has been proven to be most favorable. Type of grate Individual designs of the grates (moving - / roller grates) result in different stoking effects. This in turn requires a specific coordination for changing the speed of the feeder and the grates in conjunction with the effect of a variable primary air. All three elements (feeder speed,grate speed and primary air) have an effect on the production of steam and the O2 concentration. All three elements have their own characteristic time behavior and they influence each other.  Boundary conditions Steam and O2 movement AFTER an optimization Steam and O2 movement BEFORE an optimization  A good fireposition with correct settings The main requirements for a Firing Rate Control (FRC) for a waste incineration plant are : a) highest possible waste throughput b) highest possible steam production c) good burn-out quality d) good boiler efficiency e) conserving boiler operation In order to achieve a maximum of waste throughput it is mandatory to assure a permanent solid fire position. In order to achieve a maximum of steam production, it is necessary to keep the steam fluctuation as small (narrow) as possible. In order to achieve a good burn-out quality, again a stable fire position is required. Lower excess air increases the efficiency of the boiler. This is however limited by furnace temperatures above critical values and by a build up of CO stratifications. Avoiding local temperature peaks in connection with a reducing atmosphere increases the operation time and helps to prevent unscheduled repare works. The conflict of goals between a permanent desirable fire position in the center of the grates and a constant steam production - while the waste quality is changing - constitutes the main great challenge for a Firing Rate Control. Optimizing The Control of Waste Incineration Plants Dipl-Ing.Dipl.-Wirtsch.Ing Heinz-Helmut Voje Optimierung von Feuerleistungsregelungen für Optimizing Firing Rate Controls for Müllverbrennungsanlagen  Waste Incineration Plants  Objectives