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摘要

In US pulp and paper mills, there are more than 900 boilers. Power and recovery boilers are equipped with induced draft (ID) and forced draft (FD) fans to provide the air for combustion. These fans may have power ratings ranging up to 1,000 hp but can greatly benefit from some optimization. The problem is that boilers in the industry have been typically fitted with dampers to control the airflow, while the fans are connected to a constant speed motor and run continuously. The motor is run at 100% only for the air flow to be throttled back mechanically. Furthermore, the induced draft and forced draft fans that provide the air for combustion have a strategic role in defining boiler efficiency, as the accurate control of the air is critical for the combustion process. This mechanical method of control via dampers is inaccurate, which leads to excess air in the combustion chamber of the boiler, and lowers the efficiency of the boiler and potentially affects the flue gas. This inability to precisely control the air flow also may lead to flame instabilities. Therefore, the optimization of the air to fuel ratio to create the most efficient combustion is very important.