US2858197A - Process and apparatus for the production of calcium carbide - Google Patents

Description

PROCESS AND APPARATUS FOR THE PRODUCTION OF CALCIUM CARBIDE Filed Aug. 16, 1955 2 Sheets-Sheet 1 s. KGOPAL ET AL PROCESS AND APPARATUS FOR THE PRODUCTION OF CALCIUM CARBIDE Filed Aug. 16, 1955 Oct. 28, 1958 2 Sheets-Sheet 2 FIG. 2

United States Patent Ofidce 2,858,197 Patented Oct. 28, 1958 PROCESS AND APPARATUS FOR THE PRODUC- TION OF CALCIUM CARBIDE Sleds Koopal, Sittard, and Willem van Loon, Geleen, Netherlands, assignors to Stamicarbon N. V., Heerlen, Netherlands Application August 16, 1955, Serial No. 528,578 Claims priority, application Netherlands August 18, 1954 7 Claims. (Cl. 23--277) The present invention is directed to a process and apparatus for the production of calcium carbide and a combustible gas, by feeding into a furnace a solid carbonaceous fuel, e. g., coke, coal or other solid fuel with high carbon content and limestone, dolomite, burnt lime, or other sources of calcium oxide (hereinafter referred to by the generic term lime). The temperature and energy needed for the carbide-forming reaction are obtained by burning part of the fuel with a blast enriched in oxygen, blown into the fuel bed through a ring of tuyeres, the remaining fuel being used to react with the lime, so that calcium carbide is formed. The carbide is drawn off in the molten state from the bottom of the reactor.

Hitherto, it has been common practice to supply both the fuel and lime, either mixed or unmixed, at the top of the furnace, the charge sinking towards the hearth of the furnace in countercurrent relation to the hot combustion gases. A disadvantage of this way of operating the process is that the very hot, rising combustion gases cause considerable vaporization of lime components. These components sublime at colder places higher up in the bed and create many difiiculties due to blocking and bridging of the charge.

It is an object of the present invention to develop a method and apparatus for preparing calcium carbide from a solid carbonaceous fuel and source of calcium oxide, as previously set forth, while obviating the vaporization of lime components with the attendant blocking and bridging of the charge.

It is another object of the invention to devise such a method and apparatus that the calcium oxide containing material and the carbide formed therefrom does not come into contact with the hot gas current produced in the combustion of the solid carbonaceous fuel with the oxygen-rich blast.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

It has now been found that, in contrast with the method of operation of the prior art process, set forth above and previously considered essential for successful production of calcium carbide, the carbide can be successfully produced, if the calcium oxide-containing material is fed into the reaction zone in such a way that said material, as well as the carbide formed therefrom, cannot come into contact with the hot gas current produced in the combustion of the solid fuel with the oxygen-rich blast.

In carrying out the method of operation according to the invention, a minor amount of carbonaceous material, e. g., 0% up to 10% of the total amount of carbonaceous material, preferably is mixed and burned with the incoming lime charge for the purpose of preheating the charge in an amount of 0 parts of lime by weight. In actual practice of the present invention, the difiiculties mentioned above in connection with the prior art procedure were completely solved and it was found that, by combustion of the fuel in the hearth zone, sufficient heat was radiated to the zone of carbide formation to effect a rapid and nearly quantitative conversion of the lime into calcium carbide.

It is known that, for the carbide-forming reaction to occur, considerably higher temperatures are required than for the preparation of combustible gases by counter-current gasification of solid fuels with oxygen and steam or carbon dioxide or oxygen with both steam and carbon dioxide. Thus, for the carbide forming reaction, temperatures of 2400 C. to 3000 C. are employed, while in preparing the combustible gases, temperatures of 1600 C. to 2000 C. are required. Nevertheless, with the method according to the present invention, sufficient heat is left in the gases which rise from the fuel bed to supply sufficient calories for utilization by blowing steam or carbon dioxide, or a mixture of these gases, over the hearths into the generators, in order to convert this steam with part of the coke or other carbonaceous fuel supplied into carbon monoxide and hydrogen or to convert the carbon dioxide to carbon monoxide.

Illustrative ways of carrying out the invention will now be described with reference to the accompanying drawing, in which Figure 1 shows in longitudinal section partly diagrammatically a suitable furnace, in which the method according to the invention can be carried out; and

Figure 2 shows a similar furnace with modified means for introducing the lime charge.

Referring to Figure 1, a furnace chamber 1 is provided at its top with a filling lock It: for the supply of the carbonaceous fuel, e. g., coke or coal, and at the bottom with an underfeed device 2 for the supply of lime. The furnace chamber is furthermore provided with a ring of tuyeres or burners 3 for the supply of the oxygencontaining blast, a ring of blast openings 4 at some dis tance over these burners for the supply of an endothermic gasification agent, e. g., steam or carbon dioxide, a discharge opening 5 for the gas produced and a tap hole 6 for the removal of the carbide produced.

The underfeed device 2 is fed via a conduit 8 from a bunker 8a, filled with lime, while the discharge from the device 2 into the furnace chamber takes place through conduit 7, which may, if desired, be equipped with feed pipes fa for air or oxygen for burning a minor amount of carbonaceous material to preheat the lime charge.

Q-enerady (with either the furnace of Figure 1 or that of Figure 2), for every 1000 kg. of calcium oxide fed into the furnace chamber 1 through underfeed device 2, there are ted 3800 to 4800 kg. of coke through filling lock in; 2000 to 3000 kiloliters (standard temperature and pressure) of oxygen from the tuyeres 3, 500 to 900 ltiloliters of steam or carbon dioxide (standard temperature and pressure) from blast openings t and, preferably, 0 to 350 kiloliters (standard temperature and pressure) of oxygen through feed pipes 7n. As previously indicated, there can be mixed with the lime charge, e. g., in bunker 8a, 0 to 400 kg. of carbonaceous fuel, e. g., coke, per 1000 kg. of lime.

The underfeed mechanism proper of Figure 1 consists of a hydraulic ram 9, connected to a plunger 10 guided in a cylinder 11. The cylinder pivots about a horiis attached to the upper end of the cylinder.

parts up to 40 parts per 3,, ns Q a hydraulically driven plunger 14, the cylinder can be reciprocated in such a way, that in the one'position its upper end connects to the conduit 8, the plunger then being in its lowermost position, and the conduit 7 being closed; by the slide. al ve 13, In this position, the cylinder 11 may be filled with the lime ar e ii st uemla hem-singe 1.0. e ur e t h position illustratedfso that conduit #1 is closed by slide valve 13 and cylinder. ll'co 'in ects to conduit 7, so that the plunger may. push the lime. content of the said cylinder into the, conduit 7,

The apparatus according to Figure 2 comprises a furnace of l thesametypeas shown. in Figure l, but pro e th li ht d f ren unde e d. me This. underfeed'mechanisrn consists of a housing 15, capable of rotating about a vertical axis, in which housing there are two. cylinders 1 1;'. The housing is rotatable. on the ball; bearings v 1Q by. means of a worm gear 17. u

In the cylinders 11 there are plungers 10 which can e m v d up anddqw hy rau ic a draulicranrs 9 are actuatedby an oil pump 18, located in the center of ,-th e .housing 1-5. The underfeed device is so mounted that, when one cylinder 11' is under the bunkerchamber 19, the other. cylinder 11 is under the delivery conduit 7 The operation of this underfeeddevice is as follows:

Lime frorn bunker 8g is fed along conduit 8 by means of: a worm 3 into bunitcr 19, From bunker 19, the material drops into theone cylinder 11. The plunger liii appertaining tothis cylinder is then in its lowermost position, while'the. plunger T0, of the cylinder located under the conduit 7 has just. pushed a charge of lime from thatcylinder. into, the conduit]. Subsequently, the housing is turned so that the full cylinder ispositioned under conduit 7;; and; the. empty cylinder. is positioned under bunker 19, after which theone cylinder is filled and the other emptied.

in order. to prevent leakage of gases from the, furnace through conduit 7 to the outside, the housing 15 is surrounded by a water. seal2i).

Through the pipes 7a, hot gases for the preheating of the lime charge, can. be supplied. If desired, this. pre: heating may take place, if the lime charge is mixed with a li-ttle fuel, by combustion of; thefuel with air or oxygen supplied through the pipes, 7 1. To keep the required feed pressure in theconduit pipe-7 relatively low, a lubricant (e. g] l /z% graphite) preferably, is added to the charge in, bunker 8a.

Example Using the furnace and underfeedingdeviceof Figure 1, there were fed every hour 350kg. of calcium oxide containing 100. kg. of cokeand 3.5 kg. of graphite from bunker 8a; 1580 kg. of coke through filling lock la, 900 kilolite rs. of oxygen (standard temperature and pressure) through tuy eres 3, Q kiloliters ofcarbon dioxide (standard temperature and pressure) through blast openings 4 and 500 kiloliters of air (standard temperature and pressure) through feed pipes 7a.

We claim:

1. A furnace. suitable for preparing calcium carbide from a solid, highly carbonaceous fuel and a calcium oxide containing material comprising a hearth provided with a plurality of tuyeres, at least one feed opening for solid fuel near the top of the furnace above said tuyeres,

at least one gas discharge opening near the top of the furnace above said tuyeres, a feed opening at a point below The hy-.

calcium oxide containing material into the reaction zone.

4 the ring of tuyeres andmeans for feeding a supply ofsolid of the furnace through said lower feed opening, said furnace being adapted to produce calcium carbide while avoiding considerable vaporization of lime components and thereby avoiding difliculties due to blocking and bridging of the charge in the upper portion of the fuel bed.

2. A furnace according to claim 1, including a tap hole below the ring of tuyeres for removal of carbide product and whereinthe means for supplying calcium oxide material into the reaction zone comprises a conduit leading to said feed opening, supply means for the calcium oxide containing material and feeding means for transferring said calcinm oxide. from said supply means to said conduit, saidfeedingmeans comprising plunger means, said plunger means reciprocating between said supply means and said conduit.

3. A, furnace according to claim- 2, wherein communicating with, saidiconduittleading to said feed opening there-are gas, supplyingmeansand .wherein said plunger supply means and; said; plunger; being. in extended position when it deliverscalciumoxide to said conduit..

4. A furnace according.to, claim.3, .wherein said cylinder is pivQiabletabout a, horizontal ,axis.

5. A furnace according to claim 1, including a tap hole .belowthe ring ofittuyeres for. removal of carbide product;- and whe cm the means-for. supplying calcium oxide rnaterial intqfihe reaction; zone; comprises a. conduit leading to said feed;open ng,,supplyv means. for the,-

calcium: oxide containing'material and. feeding, means for transferringsaid calcium oxide; from said supply means.

to said conduit, said feeding means comprising a pair of t p t ngtp n e eans, aidp r means recipro cating between saidsupply means and said conduit.

6. A furnace according to claim 5, wherein communicating with saidfconduit leading to said feed opening there are gassupplyingmeans and .wherein each of said plunger; means isguided, by a cylinder, one of said plunger means being in-recessedposition;andin position to receive calciumoxidefrom thecalcium oxide supplying means when the other of said plunger means is in extended positicn and in positionto deliyercalcium oxide to said duit..

7. The furnace of-claim 6, wherein said cylinders and pair ofplunger means are housed in a housing, said housing being rotatable about a vertical axis.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A FURNACE SUITABLE FOR PREPARING CALCIUM CARBIDE FROM A SOLID, HIGHLY CARBONACEOUS FUEL AND A CALCIUM OXIDE CONTAINING MATERIAL COMPRISING A HEARTH PROVIDED WITH A PLURALITY OF TUYERES, AT LEAST ONE FEED OPENING FOR SOLID FUEL NEAR THE TOP OF THE FURNACE ABOVE SAID TUYERES, AT LEAST ONE GAS DISCHARGE OPENING NEAR THE TOP OF THE FURNACE ABOVE SAID TUYERES, A FEED OPENING AT A POINT BELOW THE RING OF TUYERES, A FEED OPENING AT A POINT BELOW CALCIUM OXIDE CONTAINING MATERIAL INTO THE REACTION ZONE OF THE FURNACE THROUGH SAID LOWER FEED OPENING, SAID FURNACE BEING ADAPTED TO PRODUCE CALCIUM CARBIDE WHILE AVOIDING CONSIDERABLE VAPORIZATION OF LIME COMPONENTS AND THEREBY AVOIDING DUE TO BLOCKING AND

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