US3207558A

US3207558A - Method and device for transmitting mixed solid-liquid fuel into the blast furnace

Info

Publication number: US3207558A
Application number: US264536A
Authority: US
Inventors: Kodama Koretaka; Shigemi Akitoshi; Ogata Toshimitsu
Original assignee: Yawata Seitetsu KK
Current assignee: Yawata Seitetsu KK
Priority date: 1962-03-17
Filing date: 1963-03-12
Publication date: 1965-09-21
Anticipated expiration: 1982-09-21
Also published as: BE629657A; GB975013A

Description

P 1965 KORETAKA KODAMA ETAL 3,207,553

METHOD AND DEVICE FOR TRANSMITTING MIXED SOLID-LIQUID FUEL INTO THE BLAST FURNACE FiledvMarch 12, 1965 2 Sheets-Sheet l INVENTOIS p 1965 KORETAKA KODAMA ETAL 3,207,558

METHOD AND DEVICE FOR TRANSMITTING MIXED SOLID-LIQUID FUEL INTO THE BLAST FURNACE Filed March 12, 1965 2 Sheets-Sheet 2 (%)---cm,00a/za/7z; M2 10 g solid/11a! Vismsz'/ (poise) /& 20 3 0 4 0 50 6b 7 0 8 0 40 /0 0 fl w 0am ill/a we) INVENTORS United States Patent 3,207,558 METHOD AND DEVICE FOR TRANSMITTING MIXED SOLID-LIQUID FUEL INTO THE BLAST FURNACE Koretaka Kodama and Akitoshi Shigemi, Yawata-shi, Fukuoka-ken, and Toshimitsu Ogata, Tobata-shi, Fukuoka-ken, Japan, assignors to Yawata Seitetsu Kabushiki Kaisha, Tokyo, Japan, a corporation of Japan Filed Mar. 12, 1963, Ser. No. 264,536 Claims priority, application Japan, Mar. 17, 1962, 37/ 10,556 7 Claims. (Cl. 302-16) The present invention relates to a method and device for transmitting mixed fuels consisting of liquidous fuel, such as heavy oil or creosote oil, and solidous fuel, such as pulverized coal or coke, into blast furnace.

Heretofore, various attempts have been disclosed in respect of methods for adding gaseous or liquidous fuel through tuyeres of the blast furnace. One of such methods employs gear pumps, and however it has been applied merely for a special liquidous fuel having relative low viscosity coeflicient.

The present invention contemplates to transmit mixed fuels consisting of liquidous and solidous one instead of simple liquid or solid fuel alone, to save coke to be used and at the same time to improve heat efiiciency in blast furnace.

That is to say, the present invention is characterized by using a tank having heating means and providing with a feed orifice for transmitting mixed solid-liquid fuel, together with a compressed gas jet pipe at the bottom thereof and the one end of said transmitting pipe being projected into the inside of the tank from the bottom thereof.

The viscosity of mixed solid-liquid fuel tends to increase proportionally to the amount of solid component, while it may considerably vary with its temperature.

As is shown in FIG. 2, the viscosity of mixed fuels may significantly be decreased by heating it to a temperature of from 70 to 80 C. In this case, however, the compounding ratio of solid fuel in the range of between and 30% may be preferable. Furthermore, it is necessary to mix up solid fuel thoroughly with liquid fuel, because the former tends to settle due to its greater specific gravity. For this purpose, the fluidity of mixed fuel may be improved by means of agitating device according to the instant invention, as will be stated below.

The present invention will be more fully described referring to a practical example as shown in the appended drawings.

FIG. 1 represents the device of the present invention and FIG. 2 the results of viscosity measurement made on mixed fuels of various composition.

Referring to FIG. 1, 1 is a tank and mixed solid-liquid fuel is charged into said tank up to 80% of its capacity through a valve 3 on feed pipe 2 from the suitable source not shown. 13 is a heating device installed in said tank and mixed fuel therein may be heated thereby. The heating device is not be limited to that shown in the drawing, any convenient type of heater may be usable so long as it may serve to heat mixed fuel. 4 is a jet pipe for compressed air or nitrogen gas, which is preferably attached eccentrically to the tank. letting or halting of compressed air may be controlled by a valve 5. 6 is an auxiliary jet pipe for compressed air, to be used when it is necessary to increase the inner pressure of the tank. 7 is an end of transmitting pipe for mixed fuel, and provided with a cover so as to prevent direct introduc- 3,207,558 Patented Sept. 21, 1965 tion of air into said transmitting pipe and to avoid the obstruction of fuel supply caused thereby. 8, 8 and 8" represent fluid control valves, 10 a pressure gauge, 11 a bypass valve, and 12 a steam valve, respectively.

When said tank 1 is charged up to about 80% of its capacity with mixed fuel through feed pipe 2, valve 3 is closed, and then said fuel is heated up to about C. by means of the heating device 13, while compressed gas is jetted eccentrically into said tank through jet pipe 4 as a vortical flow with suflicient velocity to whirl the mixture of liquid and solids so that the solids will be maintained in suspension in said liquid fuel while the gas rises vertically through the mixture in said vortical flow to prevent the settling out of the solid particles and to pressurize the mixture and to force down said fuel gradually. The pressure in said tank is controlled so as to keep it constant at 3 kg./cm. by watching the pressure gauge 10. Then,

valves

8, 8' and 8" are opened to convey said fuel into burners which are fitted near tuyeres and connected with transmitting pipe 7. When it is needed further to control and increase the inner pressure of said tank, compressed gas may be jetted in through the auxiliary jet pipe, and the flow of fuel to be added near tuyeres may be controlled or stopped by means of the

valves

8, 8' and 8" on keeping watch on the flowmeter 9. When said fuel in the tank has been fed out under pressure in this manner, valve 8 is closed at once and only the valve 3 is opened to lead out gas in the tank; in the same procedure, newly replenished fuel will be supplied to blast furnace. During this operation, the steam valve 12 is opened to jet residual fuel in the burners into tuyeres for cleaning burners with steam. Continuous supply of said fuel may be effected by providing a plurality of tanks. Further, the transmitting pipe 7 may be cleaned with compressed air etc. jetted into the tank by opening valve 11. When the whole fuel in the tank has been supplied, burners may be cleaned by blowing residual fuel into tuyeres by means of steam by opening valve 12. In this case, valves 8 and 8' are to be closed.

As above-mentioned, in accordance with the present invention it may be expected that the amount of coke to be consumed may be saved by blowing mixed solidliquid fuel into the bosh zone of a blast furnace.

In general the combustion of mixed fuel is more complicated as compared with those of either liquid only and solid only. Namely, the following steps are necessary in mixed fuel combustion: compounding-mixingheating agitation transmitting evaporation combustion. The period required for from atomization of fuel at the fore ends of tuyeres to its combustion depends substantially on the transmitting rate of heat supplied extraneously.

If the blow burners are located at the fore ends of nozzles (the entrance of tuyeres), the fuel may be heated in tuyeres without combustion, while it may be rapidly burned only at the high temperature zones at the fore ends of tuyeres in the furnace.

The flame length obtained in the case of mixed fuel combustion depends on the atomizing period, the size of liquid drops atomized and the size of particles of solid fuel. Therefore, it is preferable to limit the size of pulverized coal particles etc. to under mesh.

In tests carried out under control of flow rate so as to obtain complete combustion, it was found that it was optimum for furnace condition to blow-in mixed fuel in an amount of 10 liters/min. (Oil 21 kg./ton of pig +pulverized coal 4.2 kg./ton of pig per tuyerc.)

The results obtained in tests with mixed fuel blown in with a device according to the present invention are shown in Table I.

4 mined quantity of said mixture, heating said mixture while so confined to decrease the viscosity thereof, simultaneously introducing a vortical flow of a compressed gas into TABLE I Blowing in of mixed fuel Amounts Blown in and Compounding Ratio Date Blowing Time Blowing Temp. of

Day/Month Oclock Minute Period discharged (minute) Oil, Pulv. coal, Ratio, Pressure, Water, C

kgJpig t. kg./pig t. percent kgJem.

I 9/1 i8: 28, 20' 18. 5 0 2. s 8/1 fig 10' 26. e 0 0 a. 0 18/12 fig g 15' 15. 0 3.1 20 3. 0 3? 16/12 lg: 2g; 15' 21. 0 4. a 20 3. 5 Comp. of Blast Furnace Gas, Percent In 100 litre of bl.

Date furn. gas Day/Month Remarks 001 00 N1 CH4 Ha Dust, g

9/1 12.20 30. 70 56. 90 0.021 0.95 0. 2223 0. 0198 Prior to blowing. 12. 40 28. 80 56. 65 0.031 1. 24 0. 2631 0. 0367 During blowing. 8/1 12. 30. 5O 55. 75 0. 021 0. 71 0. 3170 0. 0625 Prior to blowing. 12.40 30. 85 55. 60 0. 030 1. O2 0. 3624 0.1585 During blowing. 18/12 13. 05 30. 40 55. 20 0.021 1. 10 O. 1209 0. 0414 Prior to blowing. 12. 50 30. 00 56. 40 0. 023 1. 0. 1377 0. 0498 During blowing. 16/12 12. 40 31. 50 57. 10 0. 023 1. 03 0. 0580 0. 0348 Prior to blowing. 11. 65 31. 57.35 0.025 1. 33 0. 2141 0. 1582 During blowing.

In this case, the feed rate of 10 liters/min. was found optimum for operation and a lower rate causing some trouble in transmitting pipe and a higher rate rendering the combustion in the very front of tuyeres incomplete.

Also in this case, the compounding ratio of heavy oil to pulverized coal of 8:2 was found optimum, and when pulverized coal is to be compounded in a ratio more than this, it is necessary to increase the pressure in the tank to send out mixed fuel powerfully.

As before-mentioned, in this invention by using compressed air instead of gear pumps the mixed fuel is adjusted by internal pressure of the tank while agitating whirlingly in the bottom of the tank, and by means of heating device fitted in the tank, for example, spiral-piped steam heater the mixed fuel may be heated to the temperature of 70-80 C. to improve the fluidity thereof. Furthermore, when 2 or more tanks used in parallel it is possible to continuously blow the fuel freely by switching them. And if two tanks with safety valves, a flowmeter and compressed air are available, speedy transmitting of mixed fuel may be possible.

What is claimed:

1. A method for conveying a mixture of solid fuel particles and a liquid fuel comprising confining said mixture, heating said mixture while so confined to decrease the viscosity of said mixture, introducing a vortical flow of a compressed gas into said confined mixture so as to simultaneously agitate said mixture to maintain said particles in suspension in said liquid and to pressurize said agitated and heated mixture and withdrawing said heated and pressurized agitated mixture.

2. A method for conveying a mixture of solid fuel particles and a liquid fuel comprising confining a predetermined quantity of said mixture, heating said mixture while so confined to decrease the viscosity of said mixture, introducing a vortical flow of a compressed gas into said confined mixture to agitate said heated mixture to maintain said solid fuel particles in suspension in said liquid the lower portion of said confined and heated mixture to agitate said heated mixture so as to maintain said solid fuel particles in suspension in said liquid fuel and to pressurize said heated and confined mixture, selectively introducing. an additional flow of a compressed gas to maintain said mixture under a predetermined delivery pressure and withdrawing said heated and agitated mixture at a predetermined rate.

4. A method for conveying a mixture of solid fuel particles and a liquid fuel to a blast furnace comprising charging a tank up to of its capacity with a mixture of l0-30% pulverized coal particles which will pass a mesh screen and heavy oil, heating said mixture in said tank to a temperature in the range of 7080 0., introducing a vortical flow of a compressed gas selected from the group comprising air and nitrogen into the bottom of said mixture to agitate said mixture to maintain said coal particles in suspension in said oil and to pressurize to a pre-determined delivery pressure, selectively introducing an additional flow ofsaid compressed gas into the said tank above the level of said mixture to maintain the said delivery pressure and'withdrawing said heated and agitated mixture at a predetermined rate from said tank under said predetermined pressure.

5. An apparatus for conveying a mixture of solid and liquid fuels comprising in combination means for confining said mixture, means operatively associated with said confining means to decrease the viscosity of said mixture, meansto supply said mixture to said confining means, means to agitate and pressurize said confined mixture into a vortical flow path and to simultaneously pres surize said so agitated mixture and means to withdraw said agitated and pressurized mixture in'a state of decreased viscosity from said confining means.

6. An apparatus for conveying a mixture of solid fuel particles and a liquid fuel comprising in combination a tank, mixture inlet means positioned on the top of said tank, heating means operatively associated with said tank to decrease the viscosity of said mixture, means positioned on the lower portion of said tank for the introduction of a vortical flow of a compressed gas into said tank and mixture outlet means leading from said lower tank portion, the intake end of said outlet means being positioned above the said compressed gas introductive means and being shielded therefrom.

7. An apparatus for conveying a mixture of solid fuel particles and a liquid fuel to a blast furnace comprising in combination a tank, a fuel mixture inlet pipe positioned on the top of said tank, a heating device positioned within said tank, and supply pipe for a compressed gas positioned near the bottom of said tank, said pipe being positioned with the inlet end eccentric to the vertical axis of said tank and perpendicular thereto, a fuel mixture outlet pipe positioned on the bottom of said tank, the intake portion of said outlet pipe projecting upwardly into said 1 stream of compressed gas into said tank above the top surface of said mixture to maintain the desired pressure for forcing said mixture from said tank.

References Cited by the Examiner UNITED STATES PATENTS 263,307 8/82 Browne 48-200 7 1,094,078 4/14 Lovekin 158-36 X 0 1,329,967 2/20 Greenstreet 11022 XR WI-IITMORE A. WILTZ, Primary Examiner.

JAMES H. TAYMAN, 1a., MORRIS O. WOLK,

Examiners.

Claims

1. A METHOD FOR CONVEYING A MIXTURE OF SOLID FUEL PARTICLES AND A LIQUID FUEL COMPRISING CONFINING SAID MIXTURE, HEATING SAID MIXUTRE WHILE SO CONFINED TO DECREASE THE VISCOSITY OF SAID MIXTURE, INTRODUCING A VORTICAL FLOW OF A COMPRESSED GAS INTO SAID CONFINED MIXTURE SO AS TO SIMULTANEOUSLY AGITATE SAID MIXTURE TO MAINTAIN SAID PARTICLES IN SUSPENSION IN SAID LIQUID AND TO PRESSURIZE SAID AGITATED AND HEATED MIXTURE AND WITHDRAWING SAID HEATED AND PRESSURIZED AGITATED MIXTURE.

5. AN APPARATUS FOR CONVEYING A MIXTURE OF SOLID AND LIQUID FUELS COMPRISING IN COMBINATION MEANS FOR CONFINING SAID MIXTURE, MEANS OPERATIVELY ASSOCIATED WITH SAID CONFINING MEANS TO DECREASE THE VISCOSITY OF SAID MIXTURE, MEANS TO SUPPLY SAID MIXTURE TO SAID CONFINING MEANS, MEANS TO AGITATE AND PRESSURIZE SAID CONFINED MIXTURE INTO A VORITICAL FLOW PATH AND TO SIMULTANEOUSLY PRESSUREZE SAID SO AGITATED MIXTURE AND MEANS TO WITHDRAW SAID AGITATE AND PRESSURIZED MIXTURE IN A STATE OF DECREASED VISCOSIY FROM SAID CONFINING MEANS.