US242102A - Blast-furnace - Google Patents

Description

J. c. BENNETT. Blast Furnace. o. 242,1 o2. Patented May 31,1881.

I Wigwam fab-w UNITED STATES PATENT OFFICE.

JAMES C. BENNETT, OF CHICAGO, ILLINOIS.

BLAST-FURNACE.

SPECIFICATION forming part' of Letters Patent No. 242,102, dated May 31, 1881.

' Application filed October 14, 1878.

To all whom it may concern:

Be it known that I, JAMES C. BENNETT, of Chicago, Cook county, Illinois, have invented certain new and useful Improvements in Blast- Furnaces, of which the following is a specification.

My invention relates to an improvement in blast furnaces; and it consists, first, in the method of preparing raw fuel and raw ore in a common furnace-stack by subjecting them, while in contact with each other, to a hot blast, and utilizing all the gaseous products therefrom in the reduction of the metal in the lower part of the furnace in one continuous operation; second, in the construction of a blastfurnace, which is provided with suitable means for closing its top while in operation, and an open bottom through which both the products of combustion and the reduced ore pass, a series of tuyeres extending up the sides of the stack to its top, and in which stack the fire is lighted in its bottom only, in contradistinction to its top, as has been done heretofore where a downward draft has been used, whereby the whole combustion of the fuel and reduction of the ore take place at or in the lower part of the furnace only.

The objects of my invention are, first, to prepare raw fuel and raw ore in a common furnace-stack so as to dispense with the usual expensive processes and machines heretofore used for the preparation of the ore and the fuel prior to their introduction into the furnace in which the ore is to be reduced; second, to save and utilize, in the treatment and reduction of the ore in the furnace-stack, all of the gaseous products generated by the hot blast in the charring of the wood, the coking of the coal, and the roasting of the ore; third, to secure a more complete, efficient, and economical reduction of ores, and a superior product in a less given time.

The accompanying drawing represents a vertical section of a furnace which embodies my invention.

A represents a common furnace-stack, which is provided at its'top with a double chargingbell, G, or double doors or covers of any kind, which are gas -tight, and which have space enough between them to receive and discharge an ordinary charge of fuel or of ore. This furnace is preferably slightly reduced in size at its lower part, j, which is provided with an enlarged opening through which both the products of combustion and reduction pass. Passing around this stack, near its lower end, is a large blast-pipe, d, and from this pipe extend vertically a number of smaller pipes, h, each one of which is provided with a number of tuyeres, c, which pass into the stack from its outer side and a stop-cock to each tuyere, so as to control the amount and force of the blast through it.

The tuyeres 0 may be placed closer together and a greater number of them used in the lower part of the furnace, where the combustion and reduction take place, than in the upper part of the furnace, where the fuel is prepared for combustion and the ore for reduction. The pipes and tuyeres extend entirely up to the top of the furnace, so that the hot blast can be introduced just under the bell, or at any point lower down, as the circumstances of the case may require.

In order to enable the workmen to inspect every operation of the furnace, a small window of isinglass, or other equivalent substance, is placed in each tuyere, through which the workman looks, and is thus enabled to judge where to turn 011 or turn on the blast.

The tuyeres are set facing each other on opposite sides of the stack, so as to facilitate the passage of the light, and thus enable the workman to see through from side to side. Should he perceive that the reduced metal is forming what is termed a scaffold in any part of the furnace, where the reduction of the ore takes place or elsewhere, he shuts off all of the blast from the tuyeres in the bottom of the furnace, and turns it on just above those points where the scaffold is adhering to the inner walls of the stack, and these blasts produce such an intense heat and action that the adhering portions of the scaffold are cut away. In this manner the workman is enabled to prevent any and all obstructions from forming, and he has every operation of the furnace absolutely under his control at all times.

In practice the furnace is charged and operated as follows: The stack is first filled with fuel, the devices for closing the top of the stack areopened,and thenthefireislighted atthebottom in the usual manner, and this is continued until the lower portion of the furnace is filled with a solid mass of fire. During this preparatory stage no hot blast is used. The top of the furnace is then closed by the bell or other device provided for this purpose, and alternate charges of ore and fuel are then introduced in the usual manner and subjected to the operation of the hot blast, which is turned on as soon as the furnace is ready for work. The lower part of the stack forms the zone of fusion, for at this point alone the combustion and reduction of the ore take place, while the upper part of the furnace forms the zone of prepation of the fuel for combustion and the ore for reduction. It must be borne in mind that no combustion takes place in the upper part of the furnace. The zone of fusion is regulated by the workman, who, by turning on or shuting ofl" the tuyeres in the lower part of the furnace,has it always absolutely under his control. The zone of fusion is supplied with oxygen either in connection with the hot blast or by any suitable device for that purpose. The upper part of the furnace, or the zone of preparation, is kept filled with raw fuel, raw ore, and a suitable flux mixed with the ore, and the fuel and the ore are charged in from the top of the furnace in alternate layers. These layers of ore and fuel are subjected to the constant action of the hot blast,which is admitted from the upper tuyeres, and this blast chars the wood or cokes the coal, thus preparing them for combustion, and roasts and ealcines the ore for reduction. As these layers sink downward into the zone of fusion fresh layers are charged in through the top of the furnace to take their place. The constant action of the hot blast on the fuel and ore, as they are in contact with each other in the stack, generates large amounts of gaseous product, which are driven downward into the zone of fusion by the blast, where they are consumed, and help to produce an intense heat,which reduces the ore.

By thus preparing the fuel and roasting the ore in the stack not only are all of the gases generated utilized in the reduction of the ore, but all outside furnaces, ovens, and other such appliances as have heretofore been used for this purpose done away with, but the ore is reduced much more quickly, and a much better product produced than in the usual manner. It is evident that where the fuel has to be separately prepared in ovens, and the ore has to be roasted or calcined by itself, all of the gases generated therefrom by the heat are entirely lost, so far as the reduction is concerned, and that the expense of handling the fuel and ore separately, and then burning them together after each one has been prepared, is very large. All of these difficulties I entirely overcome, for the ore and fuel are charged into the top of the stack in a raw state and in direct contact with each other, and their preparation and reduction take place in one continuous operation, which can be continued for days or weeks without stopping the furnace, unless desired.

Where the ore needs further treatment, a reverberatory furnace, H, is connected to the base of the stack by means of a covered passage-way, 1). Through the side of this passage way is made a suitable opening, I, through which suitable tools can be introduced for the purpose of transferring the metal directly into the reverberatory furnace from the bottom of the stack without exposing the metal to the action of the atmosphere.

I am aware that there is nothing new in the use of a furnace having a closed top and a downward draft, and which has a reverberatory furnace in direct connection therewith, but in which the fire is lighted at the top of the charge and the products of combustion driven down through the unconsumed and unreduced portion ofthe charge. Iam also aware that the use of tuyeres in connection with a blast-furnace is old, and all these I disclaim. My invention differs from all these in having my fire and the point of reduction in the lower part of the stack, in contradistinction to a fire in the top of the furnace, and in using the top part of my stack for preparing the fuel for combustion, and for roasting the ore by means of a downward hot blast.

My invention further differs from what has been done heretofore, in using a common furnace-stack for preparing raw fuel for combustion, and roasting raw ore while the fuel and ore are in direct contact with each other, and utilizing the gaseous products derived from both ore and fuel in the reduction of the ore itself in the furnace-stack.

In short, by my new arrangement and combination of old devices and contrivances I quicken and cheapen the cost of the reduction of the ore, and obtain, by a new and more direct mode of operation, the advantages above set forth.

I am also aware that it is not new to place fuel in a retort or furnace which is closed at its top, open at its bottom, and through which a downward blast is passed for the purpose of generating a gaseous product, which is to be used in the reduction of ore in an adjacent reverberatory furnace. My invention differs from this in placing the raw fuel and raw ore together in the same furnace, and burning the gaseous products in the same furnace in which they are generated and in which the ore is smelted.

Having thus described my invention, I claim- 1. The process herein described of smelting ores, consisting in ehargin g the stack with raw ore and raw fuel in direct contact with each other, closing the top of the furnace, admitting a hot blast, thereby coking or charring the fuel and roasting the ore, and forcing the gaseous products generated by the hot blast from both fuel and ore down into the tire in the charged into the furnace from its top upon the fire in its bottom, where the combustion and reduction take place, substantially as set forth.

In testimony that I claim the foregoing I 15 have hereunto set my hand this 10th day of October, 1878.

JAMES C. BENNETT.

Witnesses:

T. F. LEHMANN, SAML. DIESGHER.

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