WO2000022174A1

WO2000022174A1 - The method of substitute fuels feed to the blast furnace

Info

Publication number: WO2000022174A1
Application number: PCT/CZ1999/000035
Authority: WO
Inventors: Bohdan Irmler; Vladislav Chrascina; Ján KRET; Ondřej KLUZA; Petr MLČOCH
Original assignee: Trinecke Zelezarny AS
Current assignee: Trinecke Zelezarny AS
Priority date: 1998-10-08
Filing date: 1999-10-05
Publication date: 2000-04-20
Anticipated expiration: 2001-04-08
Also published as: CZ288751B6; CZ323598A3

Abstract

The method of the substitute fuels feed to the blast furnace by their injection to the blast blown to the hearth, which is based on the fact, that the pulverized coal and/or scales are injected to individual tuyeres in the form of the suspension with oil.

Description

The method of substitute fuels feed to the blast furnace

Field of the Invention

The invention relates to the method of substitute fuels feed to the blast furnace bv their iniection to the hot blast blown to the hearth within the production of hot metal .

Background of the Invention

Current development of the blast furnace technoloσv of the hot metal production can be determined bv increasinσ ratio of substitute fuels blown toσether with the hot blast to the blast furnace hearth- Recentlv. the classical substitute fuels as natural as and heaw oil are replaced with blowinσ the pulverized coal- The ma oritv of oresent-dav blast furnaces works on the basis of the pulverized coal iniection, which amounts UP to 200 kg per ton of produced hot metal- In the case of blowing the heaw oil, its volume amounts ca. 60 kg per ton of hot metal .

The reasons for the extension of iniection technologies are mainlv environmental and energetic . because the substitution of significant part of expensive and deficit coke bv other fuel can reduce the coke production with all positive environmental effects. Blowing the hvdrooarbon fuels to the blast furnace hearth has also positive technological effects. The thermal state of the blast furnace bottom can be affected bv the utilization of thermal effects of chemical reactions before tuyeres and it enables to control the gualitv of produced hot metal. The overall profitability of the hydrocarbon fuels iniection to the hearth is recentlv undeniable.

The large amount of fuel conveved to the hearth together with the blast, which can recently reach a half of total fuel amount. causes the decrease of coke ratio in the blast furnace stack resulting in worse air permeabilitv of the charge column. At the blast furnace bottom, below the cohesive zone the time of coke continuance even doubles. It results in different reguirements for the coke gualitv. Therefore, the endeavour to relocate the part of the iron ore charge from the stack to the hearth is notable. Recentlv the technologv. where the Dulverized iron oxides t the iron ore Dart of the charge) are blown together with the pulverized coal. is extending. It eσualizes the conditions in the blast furnace stack . enables fabrication of powderv iron ores _? the oxvgen is also conveved to the hearth and new agent for the ho metal gualitv control is obtained.

The next possibilitv is iniection of various waste materials to the blast furnace hearth. It has also significant environmental effect. The temperature in the oxidation area of the blast furnace reaches 2 200 ^~C. This is sufficient to dissolve entirely all harmful materials. Their individual components float to the blast f rnace gas . which can be used within the energetic networks .

The maiority of technologies of the materil iniection to the blast furnace hearth is based on the combination with the iniection of the pulverized coal. However,, introduction of this technologv is very demanding to the investment costs. Among of all known technologies, there is an example of technology according to the international patent application WO 93/20244 based on iniection of the powderv iron ore to the blast furnace in PUIPOUS blend with the fuel oil and possibly with the iron oxides, e.g. in the form of scales from the hot rolling process. The fact that the scales have to be dried before mixing to the blend disadvantages this technology to a certain extent.

In this respect there is also known a solution according to the German Patent DE 4104072 describing the method of recycling oilv rolling mill scales bv their iniecting to the blast furnace in the blend with the pulverized coal. The disadadvantage of this solution is the necessity of the scale processing bv their grinding and drving to the form of solid powderv fraction usable for iniection.

Summary of the Invention

The above mentioned disadvantages of the actual technology state are in a great extent eliminated bv the method of substitute fuels SUPPIV by their iniection to the blast blown to the hearth, which is based on the fact that the pulverized coal and/or scales, either oilv or not, are conveved to individual tuveres in the form of the oil suspension.

The advantage of this method consists in the possibility of its utilization bv the blast furnaces eguipped bv the appliance for liguid fuel iniection, where installation of pulverized coal iniection appliance reguires high capital expenditures as well as technically and technologically demanding adiustment. The next advantage is the fact that the materials containing carbon and hvdrogen in the coal-oil suspension or in the oily scales substitute part of blast furnace coke with all positive effects. Moreover, replacement of oil like additional fuel with coal will reduce the gas volume in the blast furnace bottom. Iniection of materials based on iron oxide enables reduction of the sinter production or reduction of pellets amount. The transfer of charge portion from stack to hearth improves the gas dvnamic conditions in the furnace. Blowing of oilv scales, which disposure is not fully solved vet. is the environmental solution as well. It also enables utilization of energetic potential of these materials, because oilv scales from hot rolling contain besides the iron oxides also a considerable amount of inflammables of oil and grease. It is the fine-grained material, usuallv with the grain UP to 3 mm. water contents UP to 25 % wt. and oil ratio UP to 15 % wt.

The invention principle furthermore consists in the fact that the iniected suspension is fed to the blast furnace in the amount of 5 to 75 kg per 1 ton of hot metal .

The invention principle furthmore consists in the fact that the suspension alternatively contains 5 to 80 % wt. of coal with granulometry 0 to 3 mm, the rest is oil.

The invention principle ferthmore consists in the fact that the suspension alternatively contains 5 to 60 % wt. of scales with granularitv 0.001 to 3 mm. the rest is oil .

The invention principle furthermore consists in the fact that the suspension alternatively contains 5 to 60 % wt. scales, 5 to 80 % wt. coal, the rest is oil. The invention principle furthermore consists in the fact that before the distribution to individual tuveres the suspension is heated up to the temperature of 80 to 120 ~C in order to provide its sufficient viscositv and thus improved oumpabilitv of conveved blend.

The invention principle furthermore consists in the fact that the suspension is iniected to individual tuveres under the pressure bv min. 0.1 MPa higher than the pressure of the blast.

The technologv of substitute fuels SUPPIV to the blast furnace according to the invention enables among others utilization of wide assortment of coal regarding its composition as well as the characteristics. The granulometry of coal iniected to the suspension ranges from 0 to 3 mm. This enables utilization of common proceedings of coal adaptation at the coke plant. The invention principle furthermore consists in the fact that the coal conveved bv means of oil to the blast furnace tuveres has the moisture ratio up to 1Q % wt. This directly decreases the costs for preparation of coal - oil suspension. The next advantage of this invention is the fact that it does not reguire inert atmosphere within adaptation and conveyance of to the blast furnace the coal as it is still within the classical technologv of the coal blowing to the blast furnace .

Bv adding the scales to the coal - oil suspension the explosiveness of the suspension is favourably suppressed. The moisture of the scale part of the suspension amounts to max. 25 % wt.

Besides above stated advantages the financial effects consist in higher controlllabilitv of the hearth thermal state and thus the hot metal gualitv improvement, in the iron ore cost savings. in utilization of ferrous substances rom the scales . in increase of effectivitv as the result of SUΌPIV the oxvσen from the scales to the oxidation spaces in the blast furnace focus and in widening the oxidation reduction range in the focus in front of individual tuveres.

Description of the prefered embodiment

Example 1

For the utilization of the coal - oil suspension the coal is adapted to the granulometrv of 0 to 3 mm at common oowder room, then the coal - oil suspension is being prepared, conveved to the blast furnace, adiusted to the final parameters, heated to 80 to 120 ^~C and distributed to the individual tuveres . where it is iniected bv adiusted oil nozzles under the pressure min. 0.6 MPa, i. e. bv 0.3 MPa higher than the pressure of the blast. For the purpose of this example the coal - oil suspension contains 20 % wt. coal and 80 % wt. oil.

Example 2

Within utilization of the suspension scales - oil the oilv scales are prepared with the purpose of their homogenization, the scales are added to the furnace oil, the scales - oil suspension is prepared and shifted from the impulse section to the compressive section, heated uo to 80 to 120 ~C and distributed to the individual tuveres, where it is iniected under the pressure of 0.6 MPa. i. e- bv 0.3 MPa higher than the pressure of the blast. For the purpose of this example the scales - oil suspension contains 56 % wt. scales and 44 % wt. oil.

Field of the Application

This invention can be used within all works for the production of hot metal via blast furnaces with minimum of the capital expenditures.

Claims

P A T E N T C L A I M S

1. The method of the substitute fuels feed to the blast furnace within the production of hot metal bv their iniection to the blast blown to the hearth. characterized bv the fact, that the pulverized coal and/or oilv scales are conveved to the individual tuveres in the form of the oil susnension.

2. The method according to the claim 1. characterized bv the act, that the iniected suspension is fed to the blast furnace in the volume of 5 to 75 kg per 1 ton of hot metal.

3. The method according to the claims 1 and 2. characterized bv the fact, that together with the blast the suspension containing 5 to 80 % wt. coal with granulometrv 0 to 3 mm. oil in the rest, is iniected.

4. The method according to the claims 1 and 2, characterized by the fact, that together with the blast the susnension containing 5 to 60 % wt. scales with granularity 0,001 to 3 mm, oil in the rest, is iniected.

5. The method according to the claims 1 and 2, characterized by the fact, that together with the blast the susnension containing 5 to 60 % wt. scales and 5 to 80 % wt. coal, oil in the rest, is iniected.

6. The method according to at least one of above stated claims, characterized bv the fact that the suspension is heated un to 80 to 120 ^~C before iniection.

7. The method according to at least one of above stated claims . characterized by the fact that the suspension is iniected under the pressure bv min. 0.1 MPa higher than the pressure of blast.

8. The method according to at least one of above stated claims, characterized by the fact, that the moisture of the coal part of iniected suspension is max. 10 % t.

9. The method according to at least one of above stated claims, characterized by the act, that the moisture of scale part of iniected suspension is max. 25 % wt.