JPS5950732B2 - Sensible heat recovery method for hot air discharged from a cooler in sintering equipment - Google Patents

Description

[Detailed Description of the Invention] This invention is a method for effectively and efficiently recovering sensible heat from hot air discharged from a cooler for hot sintered ore in a sintering facility for iron ore used as raw material for a blast furnace. It is related to.

The temperature of the hot air discharged from the cooler of current sintering equipment is relatively low, averaging 150 to 250°C, but the amount of air is large, and the amount of heat exchanged with the hot sintered ore is limited by the sintering machine. Accounts for 40-50% of the heat intensity of 450-400Kcal/kg,
The amount of heat is extremely large.

For this reason, the necessity of heat recovery has been recognized, and various heat recovery methods have been attempted. 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. However, there are problems as described below.

First, to explain the sintering process, as shown in Figure 1, as the sintering raw material A moves from the charging side B to the exit side C, it progresses from the upper layer D to the lower layer E. .

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 will be occupied by raw materials containing moisture and raw materials that are being preheated. Further, air H drawn from the upper layer D passes through the thin thermal sintering layer where the sintering of the upper layer D has been completed in the vicinity of the non-charging B, and immediately reaches the sintering reaction layer.

Therefore, the excess air remains at a relatively low temperature and acts as combustion air for the coke, and the excess air, together with the coke combustion gas, becomes a drying and preheating source for the raw materials in the lower layer E, and itself becomes low-temperature exhaust gas for the sintering machine. It is emitted as exhaust gas. on the other hand,
The attracted air near the extraction side C passes through the thick layer after sintering is completed and reaches the sintered reaction layer at a relatively high temperature. The amount of heat on the extraction side C is in excess of that on the charging side B due to the difference in the amount of heat absorbed by preheating in the layers, and this difference in amount of heat reaches 8 to 10% of the heat unit of the sintering machine.

In reality, this difference is somewhat alleviated by the heat input to the ignition furnace and heat retention furnace on the charging side B.

Regarding air permeability, with the sintering reaction zone G as the border, the air resistance of the wet raw material layer and dry raw material layer on the charging side B is large, and the ventilation resistance on the extraction side C is large.
Since the ventilation resistance of the porous sintered layer is small, the extraction side C tends to have a bit of excess air, which means the sintering reaction temperature on the extraction side C tends to be slightly lower, and the difference in heat amount is alleviated, and the partial Even if it is not suitable in terms of performance, it is operated within an acceptable range on average, and productivity and quality are maintained at a certain level. Therefore, if hot air discharged from the cooler is uniformly supplied throughout the sintered layer, even if the coke consumption rate tends to decrease on average throughout the sintered layer, the above-mentioned It is conceivable that thermal energy is wasted within the allowable range, and thus it does not contribute to accurate reduction in heat consumption rate, that is, reduction in coke consumption rate.

On the other hand, the amount of heat that exceeds the allowable range increases, resulting in negative effects such as reduced productivity and quality. It is an object of the present invention to provide a sintering method that solves the above-mentioned problems and makes effective use of hot air discharged from a cooler.

Hereinafter, one embodiment of the present invention will be described based on FIG. 2.

Sintering raw materials consist of iron ore, powdered lime, coke powder, return ore, etc. They are supplied from each hopper 1, 2, 3, 4 to the primary mixer 5, where they are properly mixed and thoroughly kneaded with primary moisture addition. The kneaded sintering raw materials are then immediately transferred to the sintering line, but here, the amount of coke blended from the hopper 1 3 to the primary mixer 5 is the minimum necessary amount, and the amount of coke from black 1 to 3 is mixed. The mixture is distributed to the secondary mixers 6, 7, and 8, and while the secondary mixer 6 of Black 1 is left unchanged, the mixture is increased sequentially from Ya 1 to O 3 to the secondary mixers 7 and 8 of Haruka 2 and Black 3. In connection with this, secondary coke is additionally mixed from the secondary coke supply hoppers 9 and 10 and sufficiently kneaded for secondary water addition.

On the other hand, in the sintering machine 11, the upper surface of the grade type conveyor pallet 12 corresponds to the above-mentioned secondary mixers 6, 7, and 8, and the sintering raw materials sent from these are transferred onto the conveyor pallet 12. The charging hoppers 13, 14, ]5 of the stacks 1, 2, and 3 are sequentially charged in layers from the top to the bottom of the conveyor pallet 12 (JPf). 1, black 2, black 3
They are arranged in series with the order of .

Therefore, the amount of fuel coke in the sintered raw material 16 charged from each charging hopper 13, 14, 15 onto the conveyor pallet 12 in a layered manner is larger in the upper layer of the raw material and less in the lower layer. It will be distributed in a gradient manner. On the conveyor pallet 12, the coke in the upper layer of the sintering raw material 16 is ignited by an ignition gas burner installed next to the charging hopper 15, and the coke on the conveyor pallet 1 is ignited.
Combustion air is drawn from the upper layer to the lower layer of the sintering raw material 16 by the suction force by the fan 19 in the wind box J8, which is disposed below the sintering material 16. As the sintered raw material 16 moves to the extraction side, the sintering process, that is, the drying, preheating, melting and sintering reactions of the sintered raw material 16 progresses from the upper layer to the lower layer, and the sintered raw material 16 is thermally sintered. The ore is sequentially extracted from the conveyor pallet 12. The hot sintered ore extracted from the sintering machine 11 is roughly crushed by a hot crusher 20, and then
It is sent onto a grade conveyor pallet 22 in a cooler 21 with sensible heat of 00°C, where it is cooled to nearly 100°C. The sintered ore extracted from the cooler 21 is adjusted to the required particle size by a cold crusher and a cold starch, and becomes a sintered ore product for a blast furnace. Cooler 21
Cool air is supplied by fans 24 and 25 from a wind box 23 placed below a grade type conveyor pallet 22.

This cold air turns into hot air by cooling the hot sintered ore 26 on the conveyor pallet 22, and flows into the exhaust hood 27. The exhaust hood 27 has a high temperature zone 28 and a low temperature zone 2.
It is divided into 9. The high-temperature air in the high-temperature zone 28 flows through the data 31 by the fan 30, and is used as a heating medium for a heat exchanger 32 installed as a necessary heat source for other purposes or a waste heat boiler in place of this, and then transferred to the sintering machine 11. Air is supplied to the ignition furnace hood 34 in the sintering machine 11 through each branch duct 33 as necessary air for combustion and sintering promotion.
The air is supplied almost uniformly into the air supply hood 35 extending from the hot sintered ore extraction side, that is, to the entire area from the raw material charging side to the extraction side of the sintered bed. It is also supplied as combustion air to the ignition gas burner 17 via another branch duct 52. A part of the low temperature air in the low temperature zone 29 flows through the duct 37 by the fan 36 and is supplied to the sintering layer together with the low temperature air coming out of the heat exchanger 32.

By the way, in the above-mentioned sintering, the amount of fuel coke in the sintering raw material was added to the upper layer of the raw material and less to the lower layer, which is seen in the current uniform distribution method, considering the progress of the sintering process. Correcting the imbalance of heat in the sintering reaction zone, i.e. the upper layer on the charging side is insufficient in heat and the lower layer on the extraction side is in excess of heat, the excess or deficiency in heat is corrected. Therefore, even if the hot air discharged from the cooler 21 is evenly distributed throughout the sintering zone of the sintering machine 11, the heat imbalance due to the method of charging and extracting raw materials in the sintering reaction zone will Can be kept small.

On the other hand, when a method is adopted in which the sintering raw material 16 is directly supplied onto the conveyor pallet 12 from the primary mixer 5, the fuel coatus in the sintering raw material 16 supplied onto the conveyor pallet 12 is evenly distributed in the sintering raw material 16. In the case of blending into the following, a gradient calorific value correction means as described below is used.

That is, the configuration is such that a plurality of heating burners 38 are arranged on the ceiling of the air supply hood 35 at gradual intervals from the raw material charging side to the extraction side.

In that case, exhaust hot air from the cooler 21 is supplied as the firing air for each heating burner 38 via the branch duct 39 . In the above configuration, the combustion air is gradually heated in a gradient manner by the combustion heat of the heating burner 38 using gas fuel or liquid fuel, with more of the combustion air on the raw material charging side and less on the extraction side of the air supply hood 35.

Therefore, even when the amount of coke in the sintering raw material 16 is equal, the heat imbalance in the raw material charging/extracting direction of the sintering reaction zone can be suppressed to a small level, as described above. The gradient heat supply method using the heating burners 38 is based on the arrangement of the heating burners 38, but it may also be based on the burner load capacity. When the heating burner 38 is used in conjunction with the heat amount correction method, the heating burner 38 is used to compensate for the amount of coke that is difficult to follow due to the gradient or stepwise mixing method.
It is useful for adjusting the heat amount in response to load fluctuations in the heat amount of hot air from the cooler 2, particularly rapid fluctuations.

Note that 40 is a bypass line with a damper 41 for adjusting the flow rate, which is interposed between the ducts 31 and 37, and is connected to the cooler 21.
is used to adjust for load fluctuations.

42 is a damper for releasing surplus air, 43 is a damper for returning low temperature air to high temperature, 44, 45 is a dust chamber, 46, 47, 48 is a damper for supplying recovered hot air, 49
50 is a damper for adjusting the amount of exhaust gas, 50 is a dust collection/exhaust gas device,
51 is an exhaust gas chimney.

As described above, according to the present invention, in order to effectively utilize the hot air discharged from the cooler as the necessary air for the sintering machine, the sintering reaction can be carried out while the hot air is almost evenly supplied to the entire area of the sintered layer. In order to minimize the heat disparity in the raw material charging/extraction direction, the hot air from the cooler is recovered most effectively, and the heat unit of the sintering machine, that is, the coke unit, is reduced by approximately equal to the recovered heat. At the same time, it improves the quality and productivity of sintered products.

In addition, the hot air discharged from the cooler is divided into high-temperature air and low-temperature air, and before the high-temperature air is used as the necessary air for the sintering machine, a heat exchanger or exhaust gas is used as a necessary heat source for other purposes. Since it is used as a heating medium in a thermal boiler, it has the effect of more effectively recovering the sensible heat of the hot air discharged from the cooler.

[Brief explanation of the drawing]

FIG. 1 is a general sintering process model diagram, and FIG. 2 is a configuration diagram showing one embodiment of the present invention. 5...Primary mixer for sintering raw materials 6,7,8.
...Secondary mixer 9,10...Secondary coke supply hopper 11...Sintering machine, 13,
14,15...Charging hopper 16...
・Sintering raw material, 17... Gas burner for ignition, 19
...Fan, 21...Cooler, 22.
... Conveyor pallet, 23 ... Wind box,
26... Heat sintered ore, 27... Exhaust hood, 28... High temperature zone, 29... Low temperature zone, 32... Heat Exchanger, 35...
・Air supply hood, 38... Heating burner.

Claims (1)

[Claims] 1. Hot air discharged from a cooler for hot sintered ore is divided into high-temperature air and low-temperature air, and the high-temperature air is used as a heat source for other purposes. After the sintering material is used as a heating medium in the heat boiler, it is supplied almost evenly to the entire area from the raw material charging side to the extraction side of the sintering machine together with the low-temperature air as the necessary air for the sintering machine. When charging, the amount of fuel coke in the sintered raw material is increased in the upper layer of the raw material and less in the lower layer of the raw material. A method for recovering sensible heat from hot air discharged from a cooler in a sintering facility, which comprises a step of advancing a sintering process from an upper layer to a lower layer. 2 The hot air discharged from the heat sintered ore cooler is divided into high-temperature air and low-temperature air, and the high-temperature air is used as a heating medium for a heat exchanger or waste heat boiler installed as a necessary heat source for other purposes. After sintering, there is a process of supplying the necessary air of the sintering machine together with the above-mentioned low-temperature air almost uniformly to the entire area from the raw material charging side to the extraction side after sintering, and a process in which the sintered raw material flows inside the sintering machine from the raw material charging side. In the process of advancing the sintering process from the upper layer of the raw material to the lower layer as it moves from the raw material to the extraction side, the combustion air of the sintered raw material is transferred to the raw material equipment of the sintering machine by the combustion heat of gas fuel or liquid fuel. A method for recovering sensible heat from hot air discharged from a cooler in a sintering facility, which includes a step of gradually heating the air in a gradient manner, with more heating on the inlet side and less heating on the extraction side.