JPS6043409A - Method for operating blast furnace by powder blowing - Google Patents

Abstract

PURPOSE:To enable blast furnace operation with fast responsiveness and a min. cost by controlling the kind and amt. of the powder to be blown through a blast furnace tuyere in such a way that the pig iron cost expressed by the equation including the cost index of the gas produced by the blast furnace attains a min. value. CONSTITUTION:The kind and amt. of the powder to be blown into a blast furnace through the tuyere thereof is so controlled that the pig iron cost (y) expressed by the equation y=x1+x2+x3+x4-x5 (in which, x1; the cost of the coke to be charged at the furnace top, yen/t-p, x2; the cost of the raw material to be charged at the furnace top, yen/t-p, x3; cost of blasting, yen/t-p, x4; the cost of the raw material and fuel to be blown through the tuyere, yen/t-p, x5; the cost of the gas produced in the blast furnace, yen/t-p in the stage of operating the blast furnace by blowing various kinds of powder such as pulverized coal, iron oxide powder, calcium carbonate powder or the like together with blasting gas into the blast furnace through the tuyere. The blowing of various kinds of the powder through the tuyere has the effect of decreasing the pig iron cost with fast responsiveness. The powder requiring blowing most is selected at this time and is controlled so as to attain the min. cost.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a method for operating a blast furnace while injecting powder through the siding, and in particular a method for operating a blast furnace that is characterized in that the injection is controlled with the minimum pig iron cost set to zero. There are many suggestions regarding.

Conventional technology The steel industry is an energy-intensive industry, and the ironmaking sector (
[Blast furnaces, coke ovens, etc.] are said to consume more than 50% of the steel process. For this reason, the cost of pig iron is greatly influenced by the above-mentioned energy efficiency, so it is being studied from the perspective of the energy saving results of steel plants.

For example, the price of electrical energy is different at night and during the day, and the energy supply and demand balance fluctuates from moment to moment, so operating a blast furnace that takes into account these changes can achieve energy minimum, which in turn can minimize cost. It is believed that・However, the above-mentioned fluctuations have short intervals and are urgently required, so conventional control using top charge cannot be used to respond, which is a big problem. There was a point. Furthermore, there is a problem in that the conventional technology aims to achieve the minimum cost from the minimum energy, which means that accurate control is not possible, resulting in poor effectiveness.

OBJECTIVES AND SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks of the prior art, such as lack of quick response to specific operational targets and lack of effectiveness in reducing pig iron costs because the direct cost minimum is not targeted. It is.

For this purpose, the present invention provides the following method: When operating the furnace by injecting various powders together with blast gas from the blast furnace tuyeres, the type and amount of the injected powders are calculated using the following formula 1, that is, 1 y=x□+X2+ X8+ X, -X5 in formula;
Cost of coke charged at the top of the furnace (P1/1-p) X...Cost of raw material charged at the top of the furnace ('/l-1)) Included raw material, fuel cost (”/1-p)X,・
・Pig iron cost y that incorporates the blast furnace generated gas cost shown as 4 cost of blast furnace gas ([shiku-p)y...pig iron cost (Fshit, -p)
This paper proposes a powder injection blast furnace operating method, which is characterized by controlling so that the In addition, in the above formula, the blast furnace gas cost (”/
l-P) Totc, B Raw blast furnace i S M' (iii
i (do)/cal) - Blast furnace gas generation amount (Nm/1-p
)・Blast furnace gas power outlet IJ-(K0al/Nm”) +7)
It is expressed as a product.

Structure of the Invention FIG. 1 shows an apparatus for injecting powder into a blast furnace, which is employed in carrying out the present invention. The lumps of coal etc. cut out from the wet lump tack 1 and having a moisture content of about 10 cm are crushed by a dry crusher 3 to 5 to 8 g.
The powder is dried and ground to about 50 mesh and stored in a dry powder tank 5. At this time, the drying gas used is air from the blower 6 heated through an air heater as shown in the figure. At the same time, the hot air is also introduced into the dryer 4 to dry the wet coal powder, wet ore powder, etc. in the wet powder tank 2, and then stored in the dry powder tank 5'. If these stored dry powders are of one type, they are directly sent to the storage tank 8.
On the other hand, in the case of type 2s, the mixer 9 mixes and adjusts the mixture to the required ratio and stores it in the storage tank 8. The blown powder in the storage tank 8 is transferred to a lift tank 1 provided at the bottom of the storage tank.
0 and further transferred to the service hopper 11. Then, the material is blown into the blast furnace via the intermediate tank 12 and the injection tank 13, and is pressurized from the inside of the furnace by about 1 to 4''g/m2, and is then forced into the tuyere 14 and blown into the furnace.

Considering the case where pulverized coal is injected into the blast furnace using the above-mentioned device, C (coal) + K 02 (g) → Co (g)
+2200KCa13/ reacts with 9-0 to generate OO gas. However, since this reaction is exothermic, it increases the furnace heat and reduces the total cost of raw material and fuel for blast furnace generation, which ultimately helps to lower the cost of pig iron.

In addition, when iron oxide powder is injected, iron oxide (Fe2o8)
Incandescent coke (0) and Fe
208 (iron oxide J+0-+2FeO-1-Co(g)
2641 as 0”%-Bi'62Qa, and the (Fed) produced by this reaction is further converted into (FeO)+ O-+(:Fa) +OOCg) -4
73KOa'/ir, g-Fe.

2 (FeO) + (Si3- + (Fe) + (5i
n2) +563 K0a'/fcg -FeO reacts with coke and pig iron [S1], and reduces furnace heat at the same time as lowering iron temperature (Si), but both reactions increase cO gas due to direct reduction. In this sense, injection of iron oxide increases raw material, fuel cost and running cost ffi, but it reduces the cost of generated blast furnace gas and contributes to lowering the cost of pig iron. do.

Furthermore, when calcium carbonate (OaCO8) powder is injected into the furnace, caco3→OaO+002 (g) ”'K0a'
/Ic9-caa.

It reacts as follows and generates CO□ gas. This gas further reacts with the coke in front of the tuyere, resulting in COC02(+0(coke)-+2CO(g) ”2
At 0a', a large amount of high-calorie blast furnace gas of 9-coz is generated. In this sense, although the injection of calcium carbonate raises raw material and fuel costs and running costs, it is useful for significantly lowering the cost of generated blast furnace gas and lowering the total cost of pig iron.

In short, blowing various powders through the tuyeres is effective in reducing the cost of pig iron, and depending on the operating environment of the blast furnace, select the powder that needs to be injected the most at that time to minimize costs. You can control it by pointing to 0.

The advantage of powder injection in the present invention is that, as shown in Figure 2, in the case of pulverized coal, it only takes about one hour for the effect to appear and to reach a steady state after changing the injection temperature. This tendency is the same when other powders are used, and the heating time is at least about 3 hours. In other words, it is characterized by quick response.For example, during the daytime when electricity interest rates are high, iron oxide or calcium carbonate is injected to generate a large amount of high-calorie blast furnace gas, and this blast furnace gas is used to generate electricity at the top of the furnace. Generating electricity will ultimately help make cheap pig iron.

In addition, at nighttime and other times when externally purchased electricity is cheap, it is more cost-effective to lower the unit price of raw materials and fuel than to generate large amounts of blast furnace gas. It is more advantageous to blow in pulverized coal or coke powder.

FIG. 3 shows the change in the amount of blast furnace gas generated when the amount of coke charged at the top of the furnace and the amount of pulverized coal injected into the tuyere were changed without changing the electric power cost. The solid line shows a change in the conventional operating method by changing the amount of charge at the top of the furnace, and the broken line shows the method of blowing pulverized coal from the air blower according to the present invention. As mentioned above, when the power cost is high, the type with high blast furnace gas generation and low power consumption is advantageous, and when the power cost is low, the type with low blast furnace gas generation and high π consumption is advantageous. In the conventional method, this transition takes about 10 hours, but in the non-inventive method, it takes only about 1 to 2 hours, and the range of change is about twice as large as that of the present invention. It is possible to carry out advantageous operations that are adapted to each period.

Example: In a blast furnace with an internal volume of 2500 m8, iron oxide 50'' externally from the siding, calcium carbonate 40 kg/l-p, and
Table 1 shows an example of blast furnace operation when pulverized coal is injected with 50"/l-p of pulverized coal and compared with the normal operating regulations. The cost was reduced to a minimum by 1,0000'/hap compared to normal operation. -10,000, pulverized coal 50 kg/l-p at night
When injected, the cost becomes minimum operation, and the cost is 0.5,000 dore less than normal operation and 'fc.

Effects of the Invention As described above, according to the present invention, the quick-responsive operation change technology of powder injection from the tuyere can be used, so it is possible to respond well to the cost environment of blast furnace operation, which fluctuates at short intervals.
Effective cost-minimum operation can be achieved and cheap pig iron can be produced.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a blast furnace tuyere powder injection device, Figure 2 is a graph showing changes in the amount of blast furnace gas generated during pulverized coal tuyere injection, and Figure 3 is a graph showing how the blast furnace is operated according to electricity costs. It is a graph showing a comparison between the method of the present invention and a conventional method, showing the influence of changes.

Claims (1)

[Scope of Claims] 1. When operating a blast furnace by injecting powder from the blast furnace together with blast gas from the blast furnace tuyere, the following information including the type and amount of the powder injected and the blast furnace generated gas cost index is provided. A method for operating a powder injection station furnace, characterized in that the pig iron cost y shown by the formula is controlled so as to be a minimum value. Note y=x□10X2+ X8+ X4 In the Xs formula;
・Coke cost charged at the top of the furnace (''/l-1))XQ...Cost of raw material charged at the top of the furnace (''/l-1))
Fq/1-p) X,...tuyere injection source, fuel cost υA-p)X5...
Blast furnace gas cost C”/1-p)