The steel recuperators are extremely reliable but sensible to overheating and thermal shock
Falorni TECH has developed safety devices which can prevent the recuperator breakage in case of any problem consequent to electric failure.
– Safety base valve
This valve is installed at chimney base. This valve has dual function:
- Security against overheating
During operation it is necessary to avoid the overheating of the recuperator in case of lack of electric energy or stop of the air fan (this event is very dangerous for the refractory steel inside of the recuperator). In such critical event, the valve opens automatically and cold air is sucked inside the recuperator thus keeping the steel temperature below the dangerous level. - Regulation of hot air temperature
During normal conditions the security stack base valve adjusts automatically the temperature of the hot combustion air. The valve modulates its opening ratio in order to adjust the amount of cold air sucked inside the stack upward the recuperator in order to reduce the hot gases temperature. The modulation is provided by one control loop on the hot combustion air thermocouple installed in the hot air pipeline.
– Diesel Fan
The Diesel fan is installed in parallel with the main combustion air fan system. As a consequence of electrical failure in power supply the combustion air fan could stop blowing the cold air inside the recuperator.
Although the security base valve at the stack base is used to limit the recuperator overheating, in this event the risk to damage the recuperator remains very high if the electrical failure would last for long. The diesel fan is provided of diesel motor which automatically starts once the main electric fan stops.
The system is provided with flow control device that avoid the overcooling and reduces the coling flow automatically when the recuperator temperature is stabilized.
This safety system is engineered in function of furnace size and requirements of customer.
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