US 2934476 A
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April 1960 A. ZVEJNIEKS 2,934,476
APPARATUS FOR THE TREATMENT OF A soun MATERIAL WITH A HOT GAS Filed Oct. 1, 1956 2 Sheets-Sheet l INVENTOR W 2%,
BY @olw W a M A ATTORNEYS April 26, 1960 A. ZVEJNIEKS APPARATUS FOR THE TREATMENT OF A SOLID MATERIAL WITH A HOT GAS 2 Sheets-Sheet 2 Filed Oct. 1, 1956 INVENTOR BY Qua, JM 64$ 7G3 ATTORNEYS United States Patent APPARATUS FOR THE TREATMENT OF A SOLID MATERIAL WITH A HOT GAS The present invention relates to a method and an apparatus for the treatment of a solid material in direct contact with a hot gas. The invention especially relates to the treatment of oil shale, pit-coal, and similar organic materials, from which volatile constituents escape when heated, possibly during a simultaneous decomposition of the material. The invention may also be applied, however, to a mere driving off of a fluid from a material, for instance drying of peat, lignite or another combustible material.
It is known in the art to treat solid materials containing organic constituents by drying, distillation, and finally combustion in a furnace with a vertical shaft, where the feeding takes place at the top and the combustion at the bottom. However, later on furnaces have been designed where the feeding is carried out from below, at which the material is conveyed upwards through the vertical shaft and finally burnt atthe top.
The method according to the present invention comprises transporting said solid material upwards in a vertical shaft, generating a current of a hot gas by burning a combustible material in a separate combustion chamber, directing said hot gas current through said vertical shaft from the top towards the bottom in counter current direction to the movement of the solid material, removing from the bottom of the shaft the vaporizable constituents liberated from the solid material by means of the hot gases and removing the solid material, which is now substantially free from vaporizable constituents, from the top of the shaft. With this method the greatest possible yield of said products and the best heat economy is obtained.
The forthcoming two embodiments of the furnace according to the invention will be described with reference to the attached drawings, showing diagrammatic illustrations of the furnace in sectional side elevations.
As a matter of principle, the furnace according to Fig. 1 is shaped like a converted U or V, 3 indicating the larger leg or shaft of the inverted U or V figure, while 14 indicates the smaller one. The material 4 to be treated, for instance crushed oil shale, is fed into shaft 3 from a hopper 1 by a slowly rotating bowl 2, coaxial with shaft 3. The bowl is partly filled with fluid, for instance condensate from the distillation of the shale and will thereby serve as a liquid trap by means of which the furnace will be hermetically closed at this end. Bowl 2 is set into rotation on a roller bearing 19 by means of a gear 20, driven by a motor 21. The conveying upwards through shaft 3 is carried out by means of a screw 15, fixedly joined with a bar 28, which is secured to the bowl 2 and which is provided with arms 29 along its upper portion, so as to act as a stirrer. By a tube 8 the shale falls down from the top of shaft 3 into the smaller shaft 14 provided with a rotable combustion grate 9, driven by a motor 23. Shaft 14 is also provided with burners 13 to supply additional heat, when necessary, as well as to ignite the furnace. Said burners, for instance, burn oil or less valuable gaseous products generated at the operation of the furnace. Shaft 14 is provided with an extension 30 provided at the lower end with a screw 11 driven by a motor 24, for the withdrawal of remaining solid material. This end of the furnace is closed by means of a liquid trap 16.
At the combustion of the shale on grate 14 hot gases are generated, passing upwards through conduit 8 and then downwards through furnace section 3. Said hot gases are heating, distilling and pyrolizing the shale in shaft 3 under the producing of fluid and gaseous reaction products. The fluid reaction products flow downwards in shaft 3 and are taken out through orifices 5 in the Wall of shaft 3 and into a pipe 5 and gathered in a container 6. The gaseous reaction products not having condensed on the cold shale in the lower section of the shaft are evacuated by means of a device, not shown, through orifices 7' in the wall of shaft 3 and into a conduit 7. In the shaft a pressure should be maintained, negative to such an extent that the surface of the fluid products is' Hence, on its way upwards the shale is heated, partly' by condensation and partly by heat convection from the hot gases. In doing so the shale dries and is subjected to dry distillation, and pyrolysis, before it falls down through tube 8 into shaft 14 where it is burnt. This combustion takes place in a manner known per se, for instance with air, probably in deficit for the producing of generator gas or with a deficit of oxygen for the producing of gas for synthesizing purpose. If desired, also steam can in a known manner be blown into the furnace for the generating of water gas. The air, the'oxygen, and the steam are preferably supplied through conduits 10 and 12. The combustion remainders are fed out by means of screws 11 and are quenched and cooled in water trap 16.
In carrying the described method into effect it is essen tial that the conditions of combustion and the flow rates in the furnace are controlled in such a manner that the shale is dried and distilled practically completely in shaft 3. In this way all fluid and gaseous distillation products produced can be recovered from the bottom of the shaft, while only the combustible products remaining after the coking of the shale will be utilized for the combustion in shaft 14.
Figure 2 shows another construction of the furnace according to the invention. In this case only a portion of the treated material is to be combusted so as to generate the hot gas current. The top section of shaft 3 is connected to another shaft 17, being provided in its lower end with a feeding out screw 25, driven by a motor 26, and a feeding out pan 27. A second feeding out screw 18 is provided in tube 8 and driven by a motor, not shown, the speed of which is controlled in such a manner that only a small portion of the distilled material, for instance pit-coal coke, moves over to shaft 14, while the main portion moves over to shaft 17. In case the co'mbustion heat of said minor portion of the coke, moving over to shaft 14, should then be inadequate to establish drying and distillation of the coal, extra heat may be supplied to shaft 14 by burning of a gas or oil. As may be contemplated, all the coke may be directed into shaft 17 in which case all the heat requested for the drying and distillation has to be generated'in shaft 14 by burning of a gas, oil or coal.
In the embodiments described above in a way of example, it has been anticipated that the furnace has been charged with oil shale or with pit-coal. As a matter of course the method may be carried out essentially in the same manner with other basic materials, able to be dry distilled. The method according to the invention may also be employed in a mere drying process, e.g. driving off water without any dry distillation or pyrolysis taking manage;
place. In thiscase ahot gas is-generated inshaft 14, for instance by burning a combustible material, said gas being conducted downwards through shaft 3. In doing so the gas evaporates the-humidity from the material 4in thetop sect-ion of shaft .3. The moisture will condense on-therising materialfurther down in shaft 3 and be gathered in container 6,, whilethe dried. material is carried over to shaft 17 and gathered in bowl 27. This drying. takes place in an advantageous mannerv from the angle of heat-econorny, as the moisture driven off from the material will not escape to the atmosphere in the state of vapor but be gatheredin: the state of liquid.
What I claim is:
1. An apparatus fo'r treating a .solid material containing .vaporizableconstituents in direct contact with a hot gas, .comprising, a furnacehaving the general shape of an inverted U the legs of which directly communicate at their upper ends through a relatively large connecting tube, .one of said legs being considerably largerthan the other legandhavingthe form ofa large substantially vertical,- cylindrical, shaft having an open lower: end, a: container intogwhich. theopenlower end of said larger.
leg-1, extends and which isya'daplted to contain a'body'ofliquid for sealing the .bottom ofsaidshaft, means for transporting, solid material through saidcontainer and into and upwards through-said shaft, a combustion. chamber in said other leg, arranged fo'r burninga combustiblematerial in a compact bed so as to forma'current of hot: gas, means. for transporting essentially the whole amount of said hot gas through the interior of said shaft municating between said tank and the interior of the lower section of said shaft by way of orifices'in the wall.
of. said shaft in operative alignment with said conduit means, and outlet means for removing substantially thewhole. amount of gaseousproductsfrom. the lower portion of said shaft said gas outlet means being located above said liquid products-removing means and consisting essentially of a gas conduit attached to a lower section of the shaft said gas conduit being connected with the interior of the shaft through orifices in the wall of the shaft, and of means for maintaining in said gas conduit a pressure lower than the pressure inside said shaft.
2. An apparatus as claimed inclaim 1, in which the meansfortranspo rting the solid material upwards through the shaft comprises a rotatable feeding bowl coaxial with and disposed-adjacent thebottom of said shaft, and in such relation to the latter as to be adapted when at least partially filled with liquid to constitute a gas seal at the bottom of said shaft, means for slowly rotating the bowl, a generally vertical transporting screw coaxial with said bowl and said shaft, the lower end of said screw being fixedly joined to said bowl, and a generally vertical stirring rod, provided. with laterally extending stirring arms, disposed in andcoaxially with respect to said shaft above; said-screw, said stirringrrod being fixedly joined at itslower. end: to. the: upper end of said screw,v and. means for deliveringv.material' to be." treated into said feedingv bo'wl.
References Cited. in..the.file ofthis patent UNITED STATES PATENTS
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