US3444048A - Continuous coking apparatus - Google Patents

Description

ay 13, 1969 SCHMEUNG ET AL 3,444,048

CONTINUOUS GOKING'APPARATUS Filed Jan. 19, 1967 6 8 r0 a ad era V n 6 104 ff khan United States Patent O Int. Cl. Cb 19/04, 1/04 US. Cl. 202-121 14 Claims ABSTRACT OF THE DISCLOSURE An apparatus for coking coal briquettes and the like by means of finely particulate solid heat exchange material moving in a closed cycle wherein a mixture of the material to be coked and of hot heat exchange material is formed in the upper portion of an upright shaft so that coking is carried out during downward movement of the mixture through the shaft, the coked briquettes or the like are separated from the particulate, now somewhat cooled heat exchange material and the separated heat exchange material is pneumatically conveyed to the upper portion of the shaft by means of a hot conveying gas so that during movement of the particulate heat exchange material towards the upper portion of the shaft, the heat exchange material is again heated in contact with the hot conveying gas.

BACKGROUND OF THE INVENTION It is known to produce coke briquettes by forming briquettes of coal and a binder such as pitch or sulfite waste liquors and thereafter coking the thus-forming briquettes in conventional coke ovens. To produce coke in conventional coke ovens requires between about 15 and hours and for this reason, the yield per unit of coke oven volume is relatively low.

The present invention proposes a more efliective ap paratus for the continuous coking of shaped bodies.

According to the present invention, continuous coking of shaped bodies adapted to be coked, particularly coal briquettes in contact with solid particulate heat exchange material is to be carried out in a technically simple and economical manner and within a very short period of time so as to give a high yield per unit of apparatus volume.

SUMMARY OF THE INVENTION According to the present invention, the effective continuous coking is achieved in an apparatus for the continuous coking of shaped bodies of a first material by contact with the hot second material consisting of particles substantially smaller than the shaped bodies of first material, whereby the apparatus comprises an upright shaft having an upper and a lower portion spaced from each other by an intermediate shaft portion, first and second introducing means communicating with the upper portion for respectively introducing the first and second material into the upper shaft portion so as to form therein a mixture which will fill the shaft up to a predetermined level, withdrawing means communicating with the lower end portion of the shaft for withdrawing successive quantities of the mixture of now coked first material and somewhat cooled second material therefrom, which withdrawing means include first treating means for loosening the withdrawn mixture and second treating means for separating the second material from the thus loosened mixture. The separated second material passes then into fiuidizing means which communicate with the above-mentioned second treating means, wherein a fluidized bed having a predetermined upper level is formed of the separated second material. Furthermore, conveying means are provided which include conduit means communicating with the second introducing means in the zone of the upper end of the shaft and also communicating with the fiuidizing means in the zone of the fluidized bed therein, for passing hot gas therethrough in the direction from the fiuidizing means towards the second introduction means so that the passage of the hot gas through the conduit means will cause at the point of communication between the conduit means and the fiuidizing means suction which will draw fluidized second material from the fluidized bed into the conduit means and will convey the fiuidized material in the conduit means to the second introduction means. During passage of the second material through the conduit means in contact with the hot gas, the second material will be again heated to a temperature sufficiently high so that the second material upon reaching the second introducing means and being from there introduced into the upper portion of the shaft is capable of supplying the heat required for coking the first material which also is introduced into the upper portion of the shaft.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic elevational view of an em- DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, the continuous coking is carried out in a reactor or shaft into the upper end portion of which the shaped bodies which are to be coked and the particulate heat exchange material are introduced so that a mixture consisting of the shaped bodies embedded in the particulate hot heat exchange material passes downwardly through the shaft whereby the shaped bodies are coked by being exposed to the hot heat exchange material.

At the lower portion of the shaft, the thus produced hot shaped coke bodies are separated from the particulate heat exchange material and then cooled, preferably with utilization of the sensible heat of the coke bodies. The particulate heat exchange material which has been cooled during downward passage through the shaft is then pneumatically recycled for introduction into the upper portion of the shaft, utilizing as conveying fluid a hot gas so that during the recycling the particulate heat exchange material is again heated to coking temperature by withdrawing heat from the hot conveying gas.

Certain difiiculties arise by broadly proceeding as described above, which difficulties are overcome by the specific structural features of the apparatus of the present invention.

One of the major difiiculties will be found in forming in the upper portion of the shaft a uniform mixture of the shaped bodies and the particulate heat exchange material. Mechanical mixing devices generally are unreliable due to the high prevailing temperatures and subject to frequent breakdowns. In view thereof, according to a preferred embodiment of the present invention, fluidization of the upper portion of the mixture of shaped bodies and particulate heat exchange material is accomplished in the upper portion of the reactor or shaft. For instance, steam may be blown into the mixing zone of the shaft. Thereby it is accomplished that the shaped bodies irrespective of the manner in which they are introduced into the upper shaft portion will be evenly distributed throughout the entire cross-section of the shaft.

Fluidization may be further enhanced by suitable control of the cross-sectional dimensions of the reactor corresponding to the speed of formation of distillation gases upon contact of the coal briquettes or the like with the hot heat exchange material and suitable proportioning of shaped bodies to be coked relative to hot particulate heat exchange material.

Furthermore, difficulties arise with respect to the withdrawal of the mixture of heat exchange materialiand shaped coke bodies from the lower portion of the shaft and with respect to separation of the heat exchange material from the withdrawn mixture. Here again mechanical devices tend to break down frequently. In view thereof, according to a further embodiment of the present invention, the apparatus is provided with means for injecting into the mixture withdrawn from the lower portion of the shaft gas in a shock-like manner so as to loosen the mixture and to convey the loosened mixture pneumatically over an overflow weir followed by separating of the mixture into shaped coke bodies and particulate heat exchange material by passage of the mixture across one or more inclined screens or grates, broadly referred to herein as screening means.

Furthermore, the fluid tight conveying of the separated particulate heat exchange material into the pneumatic conveying conduit for recycling is connected with ditficulties which conventionally can be overcome only by interposition of a sluicing arrangement. This, however, considerably enlarges the size of the apparatus and involves additional costs.

According to another preferred embodiment of the present invention, the particulate heat exchange material separated from the mixture by passage through the screen ing means is introduced into a fluidizing device forming therein a fluidized bed and is then pneumatically introduced into the conduit leading towards the upper portion of the shaft. In order to overcome the pressure increase between the shaft and the recycling conduit, it is preferred to convey the particulate material from the free space below the screening means into the fluidized bed device with interposition of one or more immersion tubes in which, like in a barometric tube, the particulate material will rise automatically to a height corresponding to the pressure differential between the free space below the screening means and the fluidized bed.

Finally, the reheating of the particulate heat exchange material frequently is connected with substantial difficulties. If the conveying gas which also serves to heat the particulate heat exchange material is exclusively heated in a combustion chamber, it is not possible to control the temperatures and particularly the maximum temperature of the conveying gas with the desired degree of accuracy.

In view thereof, according to a further embodiment of the present invention, the particulate heat exchange material while being conveyed in the gas conduit towards the upper portion of the shaft may be further heated with gases which are introduced through suitable gas conduits communicating with the conveying conduit upstream of the fluidized bed and preferably located closer to the fluidized bed than to the device for introducing the particulate material into the upper portion of the shaft. Furthermore, by introducing oxygen-containing gas into the recycling conduit, it will also be achieved that finely subdivided coal particles which may be carried along with the particulate heat exchange material will be subjected to combustion and thereby eliminated with production of additional heat.

Referring now to the drawing, a shaft or reactor 1 is shown, in which a mixture 2 of shaped bodies which are to be coked and of a particulate heat exchange material the individual particles of which are substantially smaller than the shaped bodies, moves downwardly from the upper portion of the shaft towards the lower portion thereof.

The diameter of the shaft is so chosen that the coking gases freed upon contact between the shaped bodies and the hot particulate heat exchange material will tend to fiuidize the uppermost portion of mixture 2 and to cause thereby a more even distribution of the shaped bodies in the particulate material. This also requires a control of the ratio of shaped bodies relative to heat exchange material, which ratio will depend on the proportion of volatilizable material in the shaped bodies.

In addition, preferably, gas inlet conduits 3 are provided for introducing gas, for instance steam, into the reactor in the zone of the upper portion of the mixture thereof in order to cause or facilitate fluidization.

It is achieved thereby, that the shaped bodies, in the upper portion of the shaft will float and thereby will be evenly distributed over the entire cross-section of the shaft and this in turn will result in the center and lower portion of the shaft in a mixture consisting of the particulate heat exchange material hiving the shaped bodies uniformly embedded therein or distributed therethrough.

Withdrawal of the mixture of now coked shaped bodies and cooled particulate heat exchange material from the lower portion of the shaft is accomplished by pneumatic means. The mixture flows into chambers 4 which at their inclined lower end portions are provided with gas conduits 5. Gas conduits 5 preferably communicate with chambers 4 through nozzle through which gas is introduced into chambers 4 in intermittent shocks. Each shock will cause a portion of the mixture to flow over overflow weir 6 onto grate or screen 7. The number of shocks per unit of time and the amount of gas per shock will control the amount of mixture which per unit of time will be withdrawn across the overflow weir. Preferably a plurality of such dosing devices or chambers 4 are arranged communicating with the bottom portion of the shaft since otherwise it would be diflicult to achieve a uniform downward movement of the mixture through the coking shaft.

The particulate heat exchange material passes through the openings in screening means 7 and flows into im-mersion tube 8 which acts as a barometric tube or like a siphon trap. The shaped coke bodies pass along the upper face of inclined screening means 7 into cooling shaft or receptacle 9. The shaped coke bodies are then withdrawn from the lower portion of receptacle 9 at a temperature of only about 200 C. by means of a mechanically operated conventional discharge device 10. Cooling of the coke in receptacle 9 may be carried out by circulating a gas between coke-filled receptacle '9 and indirect heat exchanger 11 whereby in the latter a part of the sensible heat of the circulating gas is transferred to steam or air which is to be preheated.

The particulate material passing through the openings in screening means 7 drops into tube '8 which extends into thev fluidized bed located in fluidizing device 12. Fluidizing device 12 is provided in conventional manner with a false perforated bottom through which gas, for instance preheated air is introduced in such a manner as to form at the upper face of the perforated bottom a fluidizer layer of the particulate material.

The fluidized layer communicates with conveying conduit 14 passiing through the fluidizing device, at openings 13 of conveying conduit 14' which openings are arranged in the zone of the fluidized bed, preferably in the zone of the upper level thereof.

Pneumatic conveying conduit 14 communicates upstream of the fluidizing device with combustion chamber 15 in which preheated air is reacted with a gaseous, liquid or solid fuel in such proportions that the gas passing from combustion chamber 15 into conveying conduit 14 still contains free oxygen. This will prevent excessive temperature peaks in the conveying gas. Preferably, the temperature of the flue gases which are introduced from combustion chamber into conveying conduit 14 will be several 100 C. higher than the temperature of the particulate material of the fluidized bed.

The free oxygen remaining in the combustion gas will serve for burning small coke particles carried along with the particulate heat exchange material so that additional heat is created in conduit 14 and at least partially transferred to the particulate material carried along by the gas in conduit 14.

In addition, one or more gas conduits '16 may be provided, communicating with conduit 14 upstream of fluidizing device or chamber 12 and preferably closer to chamber 12 then to the upper portion of shaft 1, for introducing additional fuel for combustion with the free oxygen of the gas flowing through conduit 14. The temperature of the gas in conduit 14 should be sufficiently high so that the particulate heat exchange material while passing through conduit 14 is heated to a temperature which is between about 50 and 200 C. above the coking temperature required for coking the shaped bodies in shaft 1.

Conduit 14 terminates at its upper end in a separator 17 from which gas escapes through conduit 18, whereas the particulate material carried along into separator 17, due to the larger cross-sectional dimensions of the latter, will not be carried to conduit 18 but will drop through the funnel-shaped portion 19 of separator -17 into tubular conduit 20. Tubular conduit 20 extends downwardly into the upper portion of shaft 1 so that the lower open end of conduit 20 will be below the upper level 24 of the upper fluidized zone of mixture 2.

The gas pressure differential between shaft 1 and separator 17 is overcome by a column of particulate material in conduit 20. This makes it possible to withdraw the heating gas through conduit 18 and separately therefrom the distillation gases from shaft or reactor 1.

Depending on the type of shaped bodies which are to be coked, for instance depending on the composition of coal briquettes, it may be advantageous to preheat the shaped bodies prior to introduction into shaft '1, or even to subject the shaped bodies to some degree of low temperature distillation.

If this is desired, the present invention provides for conduit means recycling heat exchange gas from receptacle 9 through conduit 21 into storage means 22 into which, preferably from above, the shaped bodies which are to be coked are introduced. In storage means such as hopper 22, the shaped bodies are contacted by the gas which has been heated in receptacle 9 in contact with the hot shaped coke bodies and thus partially distilled bodies are then introduced through conduit 23 onto the upper portion of shaft 1. The gas which has been cooled to some extent while being in contact with shaped bodies in hopper 22 passes through conduit 24 to be reintroduced into receptacle 9. Conduit 24 includes a condensing device 25 for condensing and separating condensible volatilized products formed in hopper 22. Excess gas and vapors which cannot be condensed may be withdrawn through conduit 26.

The following examples are given as illustrative only, without, however, limiting the invention to the specific details of the examples.

Example 1 Egg-shaped briquettes each weighing 24 grams and formed of 93.6% fine coal including 9.2% volatile con stituents and 6.4% pitch are continuously coked in a reactor such as shaft 1, having an inner diameter of400 mm. and a height of 4 meters. Sand having a particle size of between about 0.2 and 0.5 mm. is used as the particulate heat exchange material. The withdrawal and dosing device 4 communicating with the bottom portion of reactor 1 has a diameter of 200 mm. and a height of 400 mm. Every 0.5 second about 0.3 standard cubic liter of gas is shock-like introduced through tube 5,

, '6 thereby causing a portion of the mixture to be transported onto grate 7. The shaped coke bodies rolling downwardly along the upper face of grate 7 are introduced into a receptacle 9 having a height of 1.2 meters and a diameter of 250 mm. Cold inert gas which has been formed by consumption of the oxygen present in the initially introduced air is circulated between receptacle 9 and heat exchanger 11.

The thus cooled coke bodies having a temperature of about 150 C. are withdrawn at 10'.

Immersion tube 8 in which a column of particulate material is formed of the sand passing through the openings of grate 7, has an inner diameter of 50 mm., and the fluidized bed device has a length of 50 cm. and a width of 10 cm. The height of the fluidized sand layer in fluidizing device 12 equals about 10 cm.

Conduit 14 for conveying the sand to the introduction device 17 and from there to the upper portion of shaft 1 has a width of 130 mm.

Combustion chamber 15 is fed with 150 standard cubic meters of air per hour and with an amount of fuel gas so arranged that the oxygen content of the gas leaving consumption chamber 15 equals about 7 and 8%.

Additional fuel is introduced into conduit 14 through gas conduit 16 in such amounts that upon combustion of the additional fuel the combustion gas is substantially free of oxygen.

Separator 17 has a length of 800 mm., a width of 320 mm. and a height of 360 mm., and communicates at its lower end portion 19 with pipe 20 opening into the upper portion of shaft 1 below the upper level of mixture 2 therein. Pipe 20 has a diameter of 70 mm.

By processing kg. of shaped coal bodies per hour, between about 0.6 and 0.8 metric ton of sand per hour is circulated. The sand is introduced into shaft 1 at a temperature about 1100 C. and cooled during downward passage to the fluidized bed by about C. While passing upwardly through conduit 14, the thus cooled sand is then again heated to about 1100 C.

The flue gas escaping from separator 17 through conduit 18 is free of oxygen and combustible constituents. The coal distillation gases which are withdrawn from the upper portion shaft 1 contain only as much nitrogen as is generally formed in the pyrolysis of coal. About 22 standard cubic meters per hour of coal distillation gases having a calorific value of 4100 kcal. per standard cubic meter are thus produced and recovered completely separated from the flue gases.

Example 2 The inner diameter of reactor or shaft 1 is 1.9 meters and its height equals 6 meters. 'Four withdrawal chambers 4 each having a diameter of 200 mm. and a height of 800 mm. communicate with the lower portion of shaft 1. The withdrawal chambers are rhythmically succesively charged with gas portions of about 2 standard cubic liters each. One successive charging of the four chambers requires 5 seconds. The mixture is transferred over the overflow weir of all chambers onto a single inclined screen means 7 from which the shaped coke bodies roll into a cooling receptacle 9 having a diameter of 1.2 meters and a height of 2.5 meters and wherein the coke bodies are cooled in contact with circulating inert gas to a temperature of about C.

The immersion tube 8 through which the particulate heat exchange material, sand of particle sizes between 0.2 and 0.5 mm. flows into the fluidizing device or trough 12 has a rectangular cross-section of 20 x 40 cm. Trough 12 has a width of 40 cm. and its length is 2 meters. The fluidized layer or bed formed therein has a height of 30 cm.

Conduit 14 has a diameter of 560 mm. and is charged with 2700 standard cubic meters per hour of flue gases which are free of molecular oxygen. The flue gas is produced in combustion chamber 15 by introducing into the same the entire required amount of air but only about two-thirds of the required amount of fuel gas. The remaining portion of the required fuel gas is introduced into conduit 14 through gas conduit 16.

The separation chamber 17 at the upper end of conduit 14 has a width of 1 meter, a height of 1.75 meters and a length of 2 meters. Chamber 17 terminates downwardly into a funnel-shaped receptacle 19 which again terminater at its lower end in a tube 20 having a width of 200 mm. and extending downwardly into the upper portion of shaft 1 below the upper level of the fluidized upper portion of mixture 2.

The yield of the presently described coking apparatus equals about 5 metric tons of shaped coke per hour, requiring an hourly sand circulation of 40 metric tons. The temperature of the sand at the point of introduction into shaft 1 is 1100 C., and the temperature of the mixture being withdrawn from the lower end portion of shaft 1 is about 980 C.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of coking devices differing from the type described above.

While the invention has been illustrated and described as embodied in a continuous coking apparatus wherein shaped bodies are coked in contact with a hot solid finely particulate heat exchange material, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. In an apparatus for continuously coking shaped bodies of a first material by contact with a hot second material consisting of particles substantially smaller than said bodies, in combination,

(A) upright coking means (1) having an upper and a lower portion, for downwardly passing therethrough an intimate mixture of said first and second materials, so as to coke during such passage said first material with said second material; and

(B) withdrawing means (4, 5, 6, 7) arranged below and communicating with said lower portion of said upright coking means for withdrawing from the latter successive quantities of said mixture, said withdrawing means including loosening means (4, 5, 6) for loosening the withdrawn mixture and also including separating means (7) located downstream of said loosening means for separating thus-loosened mixture into one fraction consisting essentially of said first material and another fraction consisting essentially of said second material, said withdrawing means comprising at least one inclined chamber (4) having an upper and a lower portion and communicating at its lower portion with the lower portion of said coking means, the upper portion of said chamber (4) defining an overflow Weir (6), and said loosening means comprising blower means (5) communicating with the lower portion of chamber (4) for introducing gas into the lower portion of chamber (4) below the level of weir (6), so that quantities of said mixture introduced from the lower portion of said coking means into the lower portion of chamber (4) will be caused by the thus introduced gas to flow upwardly in said inclined chamber and over weir (6) towards said separating means (7) and thereby to be loosened prior to being separated into said fractions.

2. An apparatus as defined in claim 1, and including (C) first (22, 23) and second (17, 19, 20) introducing means communicating with said upper portion of said coking means (1) for respectively introducing said first and said second material thereinto so as to form a mixture (2) filling said coking means (1) to a predetermined level (24);

(D) fluidizing means (12) located downstream of and communicating with said separating means (7) for receiving the separated second material and fluidizing the same so as to form thereof a fluidized bed having a predetermined upper level; and

(E) conveying means including conduit means (14) located outside said coking means (1) communicating with said fluidizing means (12) in the zone of the fluidized bed therein, and also communicating with said second introducing means (17) for passing hot gas therethrough in the direction from -said fiuidizing means (12) towards said second introduction means (17) to thereby cause suction at the point of communication (13) of said conduit means with said fiuidiz-ing means so as to draw fluidized second material from said fluidized bed (12) and to convey the same to said second introduction means '(17), simultaneously heating said second material by contact with said hot gas so that thus heated second material will pass from conduit means (14) into said second introducing means (17) and from there into said upper portion of said coking means (1) to forum therein a mixture (2) with said first material.

3. An apparatus as defined in claim 2, wherein said first introduction means (23) communicates with said coking means (1) at a level above the level of communication between said second introduction means (20) and coking means (1).

4. An apparatus as defined in claim 3, wherein said second introduction means (20) communicates with said coking means (1) below said predetermined level (24).

5. An apparatus as defined in claim 2, wherein said conduit means (14) communicates with said fluidizing means (12) in the zone of the upper level (13) of said fluidized bed.

6. An apparatus as defined in claim 2, wherein said separating means includes screening means (7) arranged downstream and below the level of said weir (6) for separating from said loosened mixture second material passing through said screening means (7 into said fiuidizing means (12), said first material being incapable of passing through said screening means.

7. An apparatus as defined in claim 6, wherein said screening means includes a downward inclined screen (7 for passing said first material along the upper inclined face thereof by force of gravity.

8. An apparatus as defined in claim 7, and including heat exchange means operatively associated with the lower end portion of said inclined screen (7), said heat exchange means including a receptacle (9) for receiving first material from screen (7), and gas circulating means for circulating a gas between said receptacle (9) and an indirect heat exchanger (11) so as to heat said gas in said receptacle in contact with the relatively hot first material, and to give up a portion of the sensible heat of the thus heated gas during passage thereof through said heat exchanger (11).

9. An apparatus as defined in claim 7, and including a receptacle (9) associated with the downstream end portion of said inclined screen for receiving first material from said screen, and wherein said first introduction means includes storage means (22) for storing first material prior to introduction of the same into said shaft; and including second conduit means (21) for passing gas through said receptacle (9) so as to heat the same in contact with the relatively hot first material therein, and for passing the thus heated gas through said storage means (22) so as to preheat first material therein prior to introduction of the latter into said coking means (1).

10. An apparatus as defined in claim 9, wherein said storage means comprises a hopper (22) having an upper and a lower portion and including inlet means for said first material in the upper portion and outlet means (23) in the lower portion of said hopper, said outlet means communicating with coking means (1).

11. An apparatus as defined in claim 10, and including third conduit means (24) communicating with said storage means (22) and said receptacle (9) for passing gas, which has been cooled in said storage means (22) in contact with first material, from said storage means to said receptacle, said third conduit means including condensing means (25) for condensing and separating from said gas condensable constituents thereof formed by contact of hot gas with said first material in said storage means.

12. An apparatus as defined in claim 3, and including first gas introducing means (3) communicating with the upper portion of said coking means (1) below the level of communication between said second introduction means (20) and said treating means (1) for introduction of gas into the latter so as to fluidize the mixture of first and second material located in the zone of the level of communication between said first gas introducing means and said treating means.

13. An apparatus as defined in claim 6, wherein said separating means includes conduit means (8) extending from below said screening means into said fiuidizing means (12) below said predetermined upper level of said fluidized bed for passing separated second material from said separating means into said fiuidizing means.

14. An apparatus as defined in claim 2, and including second gas introducing means (16) communicating with said conduit means (14) upstream of said fiuidizing means (12) and farther distant from said second introduction means (17, 19, 20) than from said fiuidizing means (12) for introducing additional gaseous fuel into said conduit means for combustion therein so as to raise the temperature of the gas flowing through conduit means (14) towards second introduction means (17, 19, 20) into said conduit means.

References Cited UNITED STATES PATENTS 2,131,702 9/1938 Berry 201-6 2,480,670 8/1949 Peck 201-28 2,741,549 4/1956 Russell 201-31 2,743,216 4/1956 Jahnig et al. 201-12 2,879,208 3/1959 Brice 201-31 2,984,602 5/1961 Nevens et a1. 201-12 3,117,064 1/ 1964 Friedrich 201-12 3,140,240 7/1964 Fowler 201-12 FOREIGN PATENTS 1,135,419 8/1962 Germany.

WILBUR L. BASCOMBE, JR., Primary Examiner.

US. Cl. X.R.

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