Energy Conservation in Boiler House by Using Variable Speed Control

ABSTRACT Boilers should always be supplied with more combustion air than theoretically required in order to ensure complete combustion and safe operation. At the same time, boiler efficiency is very dependent on the excess air rate. Therefore, the excess air should be optimized to increase the system efficiency. In this study, the effect of the excess air ratio on the efficiency of the boiler system was investigated in a water tube boiler that has the capacity of producing 20 bar pressure and 55 ton steam at 245°C. The boiler combustion air is supplied from a fan driven by a 30kW at 1450 rpm induction motor. Since the fan motor, running at nominal speed, has supplied the same air flow rate, excess air amount and exhaust gas temperature were very high at low loads. In that stage, boiler efficiency was low due to thermal energy losses, which also consequently leads to electrical energy losses. The steam requirement of the factory changes because of the tire process. For example, in the tire cooking machines...