JPS5933178B2 - Sensible heat recovery method for hot air discharged from a cooler in sintering equipment - Google Patents

Description

Detailed Description of the Invention This invention relates to a cooling zone constructed by extending the length of a sinter cooler or sintering machine in a sintering facility for iron ore used as a raw material for a blast furnace, that is, a cooling ono-strand method. This invention relates to a method for recovering the sensible heat of hot air discharged from the cooling zone of the sintering machine as effective heat of the sintering machine.

The temperature of the hot air discharged from the cooler of current sintering equipment is relatively low at an average of 150 to 250°C, but the amount of air is extremely large, and the amount of heat exchanged with hot sintered ore is Heat unit of machine 450-400Kcal/I (40-50% of 9
occupies a huge amount of heat.

For this reason, the necessity of heat recovery has been recognized, and various heat recovery methods have been tried. One method is to use the hot air discharged from the cooler as combustion air and sintering promotion air for the sintering machine, but the current usage method is to distribute the hot air discharged evenly over the entire sintered layer. There are some problems as described below.

First, the sintering process will be explained. As shown in FIG. 1, the sintering process progresses from the upper layer D to the lower layer E as the sintering raw material A advances from the raw material charging side B to the extraction side C.

Therefore, the upper layer D is occupied by the thermally sintered ore that has completed sintering, and the lower layer E is occupied by the unsintered ore. This area is occupied by raw materials containing moisture and raw materials that are being preheated. On the other hand, the atmosphere H drawn from the upper layer D passes through the thin heat-sintered layer that has completed sintering in the vicinity of the raw material charging side B, and immediately reaches the reaction layer.

Therefore, it acts as coke combustion air while remaining at a relatively low temperature, is attracted to the lower layer E as exhaust gas together with excess air, becomes a drying and preheating source for the lower raw material, and becomes low-temperature exhaust gas itself as exhaust gas of the sintering machine. be discharged. In addition, the air near the extraction side C takes a long time to pass through the thermally sintered layer after sintering is completed, becomes relatively high temperature, and acts as coke combustion air. There is an excess of heat on the extraction side C compared to the raw material charging side B due to the difference in heat amount, and the difference in heat amount is around 10% of the overall heat unit.
In reality, this is somewhat alleviated by the heat input of the ignition furnace and the heat input of the insulating furnace, and even if some parts are inappropriate, the overall operation is within an acceptable range on average. Therefore, if hot air discharged from the cooler is uniformly supplied to the entire sintered layer, even if the coke consumption rate tends to decrease on average throughout the sintered layer, the above-mentioned It is conceivable that heat energy is wasted within the allowable range, and therefore does not contribute to accurate reduction in heat unit consumption, that is, reduction in coke unit consumption.

On the other hand, the portion exceeding the allowable range of heat balance increases, resulting in negative effects such as increased deterioration of productivity and quality. In order to solve the above problems, this invention uses hot air discharged from a cooling zone constructed by extending the length of the cooler or sintering machine as combustion air for coke fuel and air for promoting sintering in the sintering machine. When supplying the hot air to the sintering machine, the amount of heat of the hot air is distributed in a gradient manner in the direction of movement from the raw material charging side to the extraction side of the sintering machine, with more on the raw material charging side and less on the extraction side. Raw material charging in the sintering area
The aim is to correct the calorific imbalance in the extraction direction.

An embodiment of the present invention will be described below with reference to FIG.
The sintering raw material is mainly made of granular iron ore, and granular coke necessary for heating and sintering is mixed therein, and the fine particles are attached to larger particles and granulated to increase the permeability of the raw material layer. Kneaded with water added. Sintering raw material is sintered by sintering machine 1
The material is fed flat from a charging hopper 2 onto a grade type conveyor pallet 3.

On the conveyor pallet 3, the ignition gas burner 4 placed next to the charging hopper 2 ignites the coatus in the upper layer of the sintering raw material 5, and the exhaust gas hopper placed below the conveyor pallet 3 ignites the sintered raw material 5. Combustion air is drawn from the upper layer to the lower layer of the sintering raw material 5 by the suction force by the exhaust gas fan 7 at 6. As the sintered raw material 5 advances toward the extraction side, the sintering process, that is, the drying, preheating, melting and sintering reactions of the sintered raw material 5 progresses from the upper layer to the lower layer.
is sequentially extracted from the conveyor pallet 3 as hot sintered ore. The hot sintered ore extracted from the top of the conveyor pallet 3 is roughly crushed by a hot crusher 9, and then
It is extracted with sensible heat of 00°C onto the grade type conveyor pallet 11 of the cooler 10, where it is cooled to nearly 100°C.

The sintered ore extracted from the cooler 10 is adjusted to the required particle size by a cold crusher and a cold screen, and becomes a sintered ore product for a blast furnace. On the other hand, the exhaust hood 12 of the cooler 10 and the air supply hood 13 of the sintering machine 1 are arranged in first, second, and third zones 14 and 15, respectively, counted from the upper side of the machine.
, 16, 17, 18, and 19, and the zones of the same order are connected to each other by ducts 20, 21, and 22.

The first zone 14 on the exhaust hood 12 side is connected to the branch duct 2.
3 to the ignition zone 24. In each duct 20, 21, 22 there are induction fans 25, 26, 27.
is provided.

The induction fans 25, 26, and 27 use the atmosphere as a cooling medium for the hot sintered ore 38 to pass through the packed bed of the hot sintered ore from below as a cross flow to the flow from the charging side to the extraction side of the hot sintered ore. Pass it upwards. As a result, the first zone 14 of the exhaust hood 12 has a high temperature, and the second zone 15 has a medium temperature.
Low-temperature hot air flows into each of the third zones 16 .
That is, the first zone 17 and the ignition zone 24 of the air supply hood 13 are provided with high temperature, second zone 181tc, medium temperature,
Low-temperature hot air is supplied to the zones 19 respectively, with the result that the heat content of the recovered hot air is gradually distributed in a gradient manner, with more on the charging side and less on the extraction side of the sintered bed. This type of distribution method avoids the heat disequilibrium in the sintering reaction zone that occurs in the current uniform distribution method, that is, the upper layer on the raw material charging side has an insufficient amount of heat and the lower layer on the extraction side has an excess amount of heat compared to the actual required amount of heat. In response to this, the excess or deficiency in the amount of heat is corrected, and therefore the imbalance in the amount of heat in the raw material charging/extraction direction of the sintering reaction zone can be suppressed to a minimum. The above distribution method involves taking out the hot air of the cooler 10 systematically in relation to high, medium, and low temperatures, but when taking out the hot air of the cooler 10 all at once, in other words, the hot air to be recovered is If the temperature is to be averaged and supplied to the sintering machine 1, the distribution method described below may be adopted. In other words, the hot air taken out all at once is distributed in an inclined manner, with more on the raw material charging side of the sintering machine 1 and less on the extraction side, and less cold air from the atmosphere is distributed on the raw material charging side, and more extraction 90vc is sequentially distributed on an inclined basis. Allocate accordingly. This allows the required amount of air to be applied almost uniformly over the entire area of the sintered layer, and the amount of heat can be distributed in a gradient manner, with more on the raw material charging side and less on the extraction side.
Such a gradient heat supply method is similarly applied to the hot air discharged from the cooling zone constructed by extending the length of the sintering machine.

In addition, 28, 29, 30, 31 in the figure are each zone 17, 1
8, 19, and 24 are cold air pushing fans used for temperature adjustment; 32, 33, and 34 are flow rate adjustment dampers; 35 is an excess air release damper; 36 is a dust collection/exhaust gas treatment device; and 37 is an exhaust gas chimney.

As described above, according to the present invention, the amount of heat of the hot air discharged from the cooler is gradually distributed in a gradient manner, with more on the raw material charging side of the sintering machine and less on the extraction side. Raw material charging/
In order to minimize heat imbalance in the extraction direction, the hot air from the cooler is recovered most effectively, reducing the heat unit of the sintering machine, that is, the coke unit, by approximately equal to the recovered heat, and reducing the heat consumption of the sintered product. Improve quality and productivity. Furthermore, by reducing the coke consumption rate, there is also the effect of reducing the generation rate of NOx and SOx in the exhaust gas from the sintering machine. There is a concern that if the amount of coke decreases, the permeability of the sintered layer will deteriorate, hindering the progress of the sintering process, and reducing productivity, but the actual ventilation resistance of the sintered layer depends on the raw material loading. The ventilation resistance of the unsintered layer at the bottom of the input side is extremely large compared to the ventilation resistance of the sintered layer at the top of the extraction side, and the ventilation resistance of the bottom of the raw material charging side mainly affects productivity. , there is no adverse effect on air permeability due to the reduction in the amount of coke.

Rather, by reducing the amount of coke by this method, the ventilation resistance due to the total reduction of the sintered layer is balanced, and more uniform optimal conditions can be maintained over the entire area, which can be expected to further improve productivity and quality.

[Brief explanation of the drawing]

FIG. 1 is a general sintering process model diagram of a sintered layer, and FIG. 2 is an overall configuration diagram showing one embodiment of the present invention. 1...Sintering machine, 2...Charging hopper, 3
...Pallet, 4...Ignition gas burner, 9...Hot crusher, 10...
・Cooler, 12...Exhaust hood, 13...
...Air supply hood, 14, 15, 16 and 17, 18,
19... 1st, 2nd, 3rd zone, 24...
...Ignition zone, 25, 26, 27...Yuki fan, 38...Hot sintered ore.

Claims (1)

[Claims] 1. When supplying hot air discharged from a cooler for hot sintered ore or a cooling zone constructed by extending the length of the sintering machine to the sintering machine as combustion air for coke fuel and air for promoting sintering, In the sintering equipment, the amount of heat of the hot air is distributed in a gradient manner in the direction of movement from the raw material charging side to the extraction side of the sintering machine, with more on the raw material charging side and less on the extraction side. Sensible heat recovery method for hot air discharged from a cooler.