US1729973A - John w - Google Patents

Description

"fact. 1, 1929.

J. W. WALTON GAS EXTRACTOR 2 Sheets-Sheet 1' Filed March 21, 1928 Oct. 1, 1929 J. W. WALTON Filed March 21, 1928 2 Sheets-Sheet 2 ,Izumazor J m/7d Z!) stares FEQE S'GHN VJ. W'A'LTGN, 0F ROCKDALE, TENNESSEE, ASSIGNGR TO TENNESSEE PRODUCTS CGRPORAIIGN, OF NASHVILLE, TENNESSEE, A GORPORATIGN OF TENNESSEE GAS EXTRAGTOR Application filed March 21, 1928.

This invention relates to gas extractors, and more particularly to means or apparatus for withdrawing gases from the interior of a continuously operating blast furnace.

The particular application of the present disclosure is to the process of recovering phos phorus as a by-product in the production of ferro-phosphorus in a blast furnace, although it is equally applicable to the withdrawal of 10 gases in any blast furnace operation.

I have discovered that gases rich in phosphorus exist in the lower parts of the fur nace, and that by withdrawing these gases directly from the furnace and subjecting them to a cooling process, the phosphorus can be recovered. in a pure and useful form and in quantities well within the limits of commercial requirements.

While the problem of withdrawing a gas from any desired point in a blast furnace does not appear on its face to present any serious difficulty, the fact of th matter is that especially designed equipment andcareful handling of the apparatus is necessary to the success of this operation. Chief among the difficulties attending the operation are, first, the extremely high temperatures encountered, and second, the difliculty of holding back the solid matter while permitting the gases to pass. In short, the problem of withdrawing the gases from a blast furnace is something more than merely tapping through the wall of a furnace and inserting a pipe through which the gases can be conducted. The purpose of the present invention is, therefore, to provide a device which has been conveniently termed an extractor, and upon the utilization of which depends the practicability of the process of recovering phosphorus from a blast furnace.

A preferred embodiment of the invention is disclosed in the accompanying drawings, in which Figure 1 is a view in vertical section of the lower portion of a blast furnace showing the installation of the gas extractor.

Figure 2 is a view in horizontal section taken on line 22 of Figure 1 and showing the extractor installation in top plan 3 and Serial No. 263,555.

Figure 3 is an enlarged detail View of the extractor in vertical section.

To understand the apparatus and its operation, a general knowledge of the blast furnace is desirable, it being understood that a furnace used in the production of ferro-phosphorus'differs only in minor respects from the typical blast furnace design.

A blast furnace consists in general of a vertical stack having an outer steel shell or jacket A and an inner refractory lining of brick B. The stack has an opening at its top into which the charge of raw materials and fuel is introduced and near its bottom is a series of tuyeres (not shown) through which air blasts are directed into the furnace. The tuyeres are usually located just below that portion of the furnace known as the bosh, this being the outwardly flaring portion just above thelower portion of uniform diameter, as shown in Figure 1. Above the bosh the walls of the stack converge or taper toward the top, there being provided near the upper end of the stack a discharge pipe termed a downcomer through which the combustible gases are conducted for use in the operation of blowing engines, heating of the air blast, and the operation of the various auxiliaries of the furnace.

Referring now to the gas extracting apparatus, the same may consist of'a single unit applied to the furnace, or a series of such units spaced an intervals circumferentially about the furnace, and all connecting with a main pipe or manifold. For the purpose of this disclosure, however, it is only necessary to describe one extracting unit, as the eXact number and location is a matter of design. Thus, Figure 1 shows a typical installation wherein the extracting unit is preferably 10- e cated ust above the level of the tuyeres and at the bottom of the bosh. where a suitable opening is formed in the wall of the stack and a nozzle-like fitting 1 is inserted, this fitting being similar in all respect to a tuyere fitting and preferably water packeted to prevent its burning out. Extending radially from the furnace and communicating with the interior thereof through the fitting l, is a pipe or conduit .2 of relatively large diameter, say 5 or 6 inches, and of a length of about a or 5 feet, although these dimensions may be varied. At the outer end of the pipe 2 is a cylindric drum 3 extending at right angles to the conduit in a vertical direction. The drum forms a chamber communicating with the pipe and extending a short distance above and below the same. At the upper end of the drum is a gas outlet in the form of a pipe l having an inverted U-bend 4 immediately above the drum outlet and a vertical branch pipe 4" leading downwardly to a main pipe or manifold 5 just above the ground level and preferably encircling the base of the furnace. The pipe 4 is made up of ordinarypipe sections and fittings, although by preference the fittings are of a suitable key-lock type which provide joints that can be quickly disconnected and con- L I nected. In fact, it is preferred to construct the entire system of pipe lines for handlin the gases with the so-called key-lock fittings, so that any section or sections can be readily torn down for cleaning and this for the reason that deposits of solid matter accumulate in the pipe and at the joints as the gases he come cooled, and hence frequent cleaning is necessary. For the same reason a clean-out opening is provided at the side of the drum 8 opposite the end of the conduit 2 and con sisting of a removable cap or plug fitting 3.

Leading from the lower end of the drum 3 is a smaller waste pipe 6 connecting with a sewer or other suitable point of disposal and having-therein a valve 6? conveniently located below the drum.

the drum and leading to a suitable source of water supply under pressure. 7 The pipe 7 is closed at its inner end by a cap 7 and throughout its length is a multiplicity of small openings or orifices 9 directed radially outward and toward the gas intake end of the conduit so thatthe water issues from the orifices in the form of a multitude of fine streams inclined to the axis thereof and toward the intake end of the conduit. The spray pipe is supported in any suitable manner, as by a bracket 10 extending diametrically of the conduit and engaging the pipe just behind the cap 7. V V

The entire apparatus for extracting the gas is designed so that it can be removed from the furnace, being preferably suspended from above by means of a rod 11 secured to the framework 12 of the furnace and having a hook at its lower end which engages an eye 13 fixed to the upper end of the drum 3. Moreover, the apparatus is held against radial displacement by two bridle rods 1d, 14 one 011 each side of the drum and conduit. These rods as fastened at one end in eyes 15, 15,1ixed to the acket of the furnace and at their outer ends extend through brackets 16, 16 on the sides of the drum, there being a resilient con- 7 nection between the rods and the drums through the medium of coil springs 17, 17 surrounding the ends of the rods and bearing against the brackets. This allows for the expansion of the conduit, the inner end of which is beveled to fit within a complementary seat in the fitting 1. V

In order to clearly understand the process of withdrawing the gas and the action of the extracting device, it willnot he necessary to enlarge upon the operation of the furnace other than to point out that in the production of form-phosphorus the furnace is charged with phosphate rock, iron bearing material, carbon and flux, the phosphate rock and iron being reduced in the high temperature zones in the lower portions of the furnace. It has been well established that the phosphate rock is reduced in the Zone of highest temperature which exists approximately at or slightly above the level of the tuyeres. Hence it is in this region that the richest and purest gases are produced, and therefore is the most desirable source of phosphorus.

In the ordinary blast furnace operation, these gases ascend in the stack and a portion of the phosphorus content being absorbed by the iron oxide to form the phosphite known as ferro-phosphorus, the remaining volume of the gases passing upwardly to the top of the stack and taken off through the clown-comer.

1 By the present method, however, a portion of the phosphorus-laden gases is withdrawn before it ascends through the zone of iron oxide reduction and treated as a source of phosphorus in a relatively pure and rich state, that is, before the phosphorus content has been depleted or the gases contaminated with impurities.

As already stated, the zone just above the tu'yeres is generally regarded as the region of greatest temperature as well as activity, and therefore to withdraw the gases directly from the furnace at this point involves the overcoming of the several difficult operating problems already mentioned. Bearing in mind, that the temperature at the level at whiehthe gases are extracted is such thatthe conduit. would be soon burned out, some protective agency is necessary. 'This then is one of the functions of the water issuing from the spray pipe 7. Due to the high temperature existing at the entrance to the conduit, the water is almost instantly converted into seam which fills the surrounding space or passage thus creating a vaporous atmosphere calculated to counteract the otherwise destructive effect of the heat upon the conduit.

The steam thus generated performs another very essential function: It is manifest that the pressure within the furnace is considerably greater than atmospheric due to the fact that blasts of air are being introduced through the tuyeres. @bviously, therefore, any opening presented for the escape of gas would also permit the discharge of solid mat ter in the form of molten rock, were not provision made for holding back the same while permitting the gas to pass. This, then, is the ethos of the steam generated within the conduit, the apparent explanation being that a suthcient back pressure is built up within the conduit to hold back the solid matter, but.allowing the gases to filter through. Moreover, the steam acts to cleanse the gases of any particles of solid matter which are carried in suspension in the form of a. dust.

This atmosphere of steam is maintained within the conduit by the constant discharge of water from the orifices in the spray pipe which is directed counter to the direction of flow of the gases. It is necessary, however,

to control the volume of water dis-charged into the conduit in order that the proper operating conditions be maintained, it being important that the gases be in a dry state when they leave the apparatus. This is controlled first, by the regulation of the water supply to the spray pipe as already mentioned, and second, by regulating the discharge of the water of condensation which accumulates in the bottom of the drum 3 by the proper manipulation of the valve in the waste pipe 6. Manifestly the steam within the conduit is being constantly condensed and collects in the bottom of the drum. Thus to insure the gases being taken off in a dry state, the drum is drained constantly so that the level of the water does not rise above the level of the bottom of the conduit.

The treatment of the gases after they have been withdrawn from the furnace and delivered into the pipe lines beyond the extracting device, admits of considerable variation, depending on the use to be made of the phos phorus to be recovered therefrom. Moreover, the processes or steps involved in the subsequent treatment of the gases is already a matter of common knowledge to those skilled in the art. In general, the treatment consists in cooling down the gases and collecting the phosphorus which condenses at the lower temperatures. As illustrative of one method of treatment, the gases are cooled down in several stages, being passed through several tanks of water having their inlets below the water level to form what is known as a water seal. In this manner the temperature of the gases is gradually lowered with an accompanying condensation of the phosphorus which collects in the tanks and recovered in its elemental form.

Another method of recovering the phos-' phorus content of thegas is to cool it down it in a chamber in the presence of air, the

phosphorus present being burned to phosphorous pentoxide P 0 which is conducted through a precipitator, preferably of the electrical type wherein the phosphorus is precipitated and recovered.

Howeventhe particular character of the gases withdrawn, the product sought to be recovered, or the processes involved, form no part of the present invention and therefore I do not wish to be limited in any of these re spects except as they are set forth in the appended claims.

Having set forth a preferred embodiment of my invention, I claim:

1. in an apparatus for the purpose described, the combination with a blast furnace, of a conduit communicating with the interior of said furnace adjacent the bottom thereof, a spray pipe extending axially of said conduit, means for supplying water to said spray pipe, means for conducting the gas from said conduit, and means for collecting and discharging the water from said conduit.

2. In an apparatus for the purpose described, the combination with a blast furnace, of a conduit communicating at one end with the interior of said furnace at a predetermined zone adjacent the bottom thereof, a relatively small pipe extending axially of said conduit and having a plurality of radially directed orifices throughout the portion adj a cent the inner end of said conduit, means for supplying water under pressure to said pipe, a water receptacle at the outer end of said conduit and a gas outlet pipe connected with said conduit.

3. In an apparatus for the purposes described, the combination with a blast furnace, of a conduit opening at one end into the interior of said furnace adjacent the zone of "the tuyeres, a water supply pipe extending axially of said conduit and having a multitude of small orifices opening radially in all directions, a collecting chamber located at the outer end of said conduit, and a gas outlet pipe leading from said conduit.

4. In an apparatus for the purpose described, the combination with a blast furnace, of a relatively short conduit extending horizontally from said furnace and communicating at one end with the interior thereof at a predetermined Zone, a water supply pipe extending axially of said conduit and provided throughout its length with a multiplicity of orifices directed radially and toward the inner end of said conduit, a drum mounted at the outer end of said conduit and extending vertically thereof, said drum having a gas outlet above and liquid outlet below the level of said conduit, and a valve in said liquid outlet.

5. In an apparatus for the purpose described, the combination with a blast furnace, of a conduit extending horizontally frorn said furnace and communicating at one end with V the interior thereof at a predetermined zone,

a water supply pipe extending axially of said conduit and provided throughout its length with a multiplicity of orifices directed radially and toward the inner end of said conduit, a drum communicating with the other end of said conduit and extending above and below the same, a gas outlet pipe connected with said drum above said conduit and a li uid outlet 3i e communicatin with said drum below the level of said conduit.

Signed at Rockdale, Tennessee this 15th day of March, 1928. 7

JOHN W. WALTON.

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