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Content archived on 2022-12-27

FLUE GAS UTILISATION IN THE HOT BLAST STOVES OF A BLAST FURNACE

Objective

To recover the energy contained in flue gases discharged when hot blast stoves are in operation. Flue gas temperature is about 275 C while the stoves heat up to 1,450 C. The heat in the flue gas is to be recovered by means of a modern rotary regenerator used to preheat the combustion air to approximately 250 C before it enters to hot blast stoves. Calculations indicate a probable energy saving of about 103,000 TOE/yr, at project level.
The system was put in operation on May 16th, 1984. Three problems - which did not interfere with the efficiency of the system - were encountered : vibrations of fans and ducting, leakage of waste gas and difficulties when changing the compensator bellows. These problems are partially solved now and will be fully solved in 1990 during the repair of blast furnace. Measurements during the period July 1984 to June 1985 show that although the installation runs actually at 90 % of design value, it is already achieving the forecast savings of 430.000 GJ/yr.
The aim is therefore attained. Licences are available.
Vibrations of fans and ducting occurred also before the installation of the rotary regeneration. In fact the problems were more serious since the vibrations were tranmitted to the burners and the host blast stoves and contributed to vibrations in the stoves itselves.
After installation of the rotary regenerator, hot stove vibrations were no longer a serious problem since the rotary regenerator acts as a damper between the fans and the stoves. Vibrations before the rotary regenerator still occur.
Heavy fan bearings are installed now and exchanged every year as preventive measure.
During the renovation of the blast furnace it is planned to exchange the fans by another type.
Energy saving in hot blast stoves stet already benefited from a number of measures i.e. optimisation of blast operation, improvement of the burners, reduction in the use of high calorific coke gas or natural gas.
It is now attempted to recover the heat contained in the flue gases generated during the heating of hot blast stoves and to use this energy the preheating of the combustion air for the hot blast stove. It is planned to use a rotary regenerator for this purpose.
The system should enable the preheating of the combustion air to approximately 250 C and to simultaneously cool the flue gases to about 125 C. The regenerator consists of a stator with heating surfaces and with tightly-fitting rotating hoods at the top and at the bottom, housing the nozzles for waste gas, air inlet and air outlet.
The regenerator is fed in counter-current and the rotating speed of the hoods is 0.8 RPM.
As the regenerator rotates, gas and air are alternatively supplied to specified segments of the regenerator, i.e. the areas heated by the gas are cyclically unloaded again by the air.

Call for proposal

Data not available

Coordinator

HOOGOVENS GROEP BV
EU contribution
No data
Address
POSTBUS 10000
1970 Ijmuiden
Netherlands

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Total cost
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