US1572326A

US1572326A - Drier kiln

Info

Publication number: US1572326A
Application number: US691198A
Authority: US
Inventors: Halver R Straight
Original assignee: Individual
Current assignee: Individual
Priority date: 1924-02-07
Filing date: 1924-02-07
Publication date: 1926-02-09
Anticipated expiration: 1943-02-09

Description

' Feb. 9', 1926.

H. R. STRAIGHT DRIER KILN 7, 1924 2 Sheets-Sheet l Filed Feb.

Feb. 9 1926.

H. R. STRAIGHT DRIER KILN Filed Feb. '7, 1924 2 Sheets-Sheet 2 jawnzbr m. 4mm-immuni QW laag Patented Feb. 9, 1.926.

- "UNITED STATES- HAL'vn n, STRAIGHT, or ADEL, Iowa.

prima. zum".

Application niearebniary 7, 11m. serial No'. 691,198;

To all whom it may concern:

Be it known that I, HALVER IL STRAIQHT, a citizen of the United States, and a resi dent of Adel, in the county of Dallas, State of Iowa, have inventeda certain new and useful Drier Kiln, of which the following is a specification.

This invention relates to improvements 1n drier kilns. l

The object of my invention is to provide a kiln of simple, durable and inexpensive construction, soconstructed and arranged that plastic ware may be passed through it in a continuous manner so that the ware will be dried very rapidly without checking or warping.

More specifically it is the object of my invention to provide a drier kiln so constructed and arranged that the kiln may be divided into a series of compartments in such a manner that air may be moved through the ware in reverse directions as it travels from y one compartment to another; and further so arranged that the air will travel at diii'erent velocities as it passes through the ware in the diderent compartments.

Another object is to so construct and arrange the kiln that the pure air may be taken into the kiln at normal temperature and passed through the kiln for drying the ware, and to introduce to the kiln quantities of heated air such as the products cf combustion from the furnaces of the burning kilns, in such a manner that the heat from the said products of combustion may be radiated to the drier for the purpose of heating the circulating air andv the ware, means being provided for introducing the products of combustion at a pointsome distance from the air intake end of the drier so that the ware may be cooled as it leaves the drier and the heat from the ware utilized in heating the ware near the center of the drier.

I have found by actual tests and observation that plastic shale' and clay, such as used to make brick and hollow building blocks, has the characteristic of shrinking quite rapidly as the first part of the moisture is being taken from the ware. After carefully plotting a curve on a percentage basis, I nd that when about tive percent of the free moisture has been taken from i the ware, the shrinkage amounts to about twentypercent; when` fifteen percent of the moisture has been taken, the shrinkage amounts to about forty percent; when thirt percent of the moisture has been remove the shrinkage is about sixty percent; and when seventy percent of the moisture has been removed, the shrinkage' is about one hundred percent.

Thus it will be seen that it is very ressential that at the beginning of the ,drying of the ware, the temperature, humidity and velocity of the drying medium, whic is usually heated air, be accurately regulated, due to the fact that the shrinkage 1s so much greater for a given percent of moisture removed in the beginning than4 at the latter part of the process.

It will further be seen that after the total shrinkage has taken place, the ware might be dried very rapidly without in'ury. I find that the best way to accomplish the desired results is to provide a means whereby the ware may be advanced throughout the kiln, and then to supply heated ainl at the delivery end of the kiln in quantities at a uniform velocity. I have -best accomplished these results by the following arrangement.

Referring to the accompanying drawings, Figure 1 is a vertical longitudinal sectional view through the intake end of my improved drier kiln. y

Figure'2 is a vertical longitudinal Sectional view of the delivery end of my improved kiln, the kiln being broken in two for the purpose of enlarging the views. The left hand end of Figure 2 is designed to join the right hand end of Figure 1.-

Figure 3 is a transverse sectional view on the line 3-3 of Figure 1.

Figure 4 is a plan view of the moisture supply pan.

Figures 5 and 6 are longitudinal sectional views taken through a modied form of my drier; and

Figure 7 is a transverse sectional view taken on the line 7--7 of Figure 5.

ed upon which the ware is designed to rest so that air freely circulate through it. Means may should be provided for driving the conveyors* The upper run is designed to receive the ware 15.

The'tun'nel is formed into a series of compartments or divisions which I shall designate as A, Awhich is the one at the ware intake end of the kiln, is of such length that when the ware has passed through it, about fifteen per slowly and uniformly cent of the moisture has been removed, at which time about forty per cent of the shrinkage takes place. It is very essential, during this state, that heated air be moved through theware 1n the direction indi-cated by the arrows, and that the air at this point have a great deal more moisture than when first entering the kiln. The moisture at this point is desirable, so as to prevent the surface of the ware through the division from drying too rapidly with a given volulne of air, the air being removed through a duct 16 and supplied through a duct 17.

In order to cause the air to travel slowly A, I have made the same considerably longer than the division F. 'The length of the intermediate divisions gradually getting shorter toward. the delivery end. -The length of this division is ll/gmfeet, while the division F is only 15 feet long. It will, therefore, be seen that the velocity of the air through the ware in the division A is only about one-third of the velocity of the air through the ware 1.11 division F. By making each successive division longer than its preceding one, it will be seen that the velocity of the air through the ware is gradually decreased.

In order to get the desired circulation of air through the ware, I have divided the kiln into a series of upper and lower compartments in somewhat staggered relation to each other. The division F has an inlet duct 17 beneath the delivery end of the said division F, and anauxiliary compartment 18 above the duct 17. This compartment 18 communicates with a compartment 19 above the ware which is substantially 71/2 feet long. The top of the compartment 19 is provided with a horizontal roof 20. The height of the roof 20 above the ware is between one and one-half and two times the height of the ware. An inclined roof 21 which extends downwardly and in the direction of the general movement of the air and is provided B, C, D, E and F, The division Y conveyor.

forv the first part of the compartment 19. The lower edge of the roof member 21 terminates at a point just above the line of the top of the Ware.

This compartment 19 communicates with a compartment 22 beneath the ware, the forward end of which communicates` with the delivery end of the compartment 23 above the ware` and in division E, which is provided with a horizontal roof 24 and an inclined roof 25. The'forward end of the compartment 23 communicates with a compart- \ment 26 beneath the ware, which communi- Cates with a compartment 27 above the ware having a horizontal roof portion 28 and an inclined roof portion 29 of division D.

The forward end of the compartment 27 communicates with a compartment 30 beneath the ware. The

compartments

18, 22 and 26 are formed by simply placing transverse partitions 31 between the wallsV `10 and beneath the upper and lower runs of the All of said compartments are provided with a horizontal floor. Approximately half of the compartment 30 is also provided with a horizontal Hoor. Approximately half of the. compartment 30 is provided with an inclined floor 32 which has in longitudinal section the shape of a hyperbola curve, as clearly illustrated. The compartment ."icommunicates with a compartment 33 similar to the compartments 27.24 and 20 with the exception that the inclined portion is curved and communicating with a compartment 34 beneath` the ware.' This in turn communicates with a compartment 35 above the ware of division B. Approximately half of this compartment is provided with a horizontal roof 3G,

and the balance with an inclined roof por# tion 37. `The said inclined portion is curved. A portion of the compartment 34 is provided with a curved bottom 38.

The compartment 35 communicates with the compartment 39 beneath the ware, which in turn communicates with the compartment v4() above the ware of division A, which is also-provided with a horizontal and curved roof similar to the compartment of division B, with the exception that they are of greater length. The compartment 39 has an inclined bottom portion 41. The compartment 4() communicates with the outlet compartment 42 and the outlet duct 1G. The upper portion of the compartment 40 is provided with a moisture pan 43, which in turn is provided with heating coils 44 having a float regulated valve 45 for the purpose of automatically supplying moisture through the supplypipe 46.

The practical operation of my drier is substantially -as follows:

Assuming that ware is being delivered to the conveyor 12 and first into division A, it will be delivered from the drier kiln at division F. The conveyor 12 is provided with an extended portion at each end outslde of the kiln for the purpose of receiving and delivering the ware. Heated air may then be delivered to the duct 17 where 1t w1ll pass upwardly through the compartment 18 into thel compartment 19, the air bein" propelled by means of an air circulating device such as now in common use, the cooled air being exhausted through the duct 16.

When the air has reached the compartment 19, it will be seen that it will be moved along the top of the roof 20 and the 1nclined portion 21 pulled downwardly through the ware most forcibly at the lowest point of the roof 21. On account of the short length of division F, it will be seen that air will move at a comparatively high velocity and that eddy currents will be set upiat the point a somewhat as indicated by the arrows.`

Thus it will be seen that the velocity of the air through the ware is comparatively high at this point. The air is then pulled through the compartment 22 into the com` partment 23 of division E. The same operation continuing through divisions E and D, eddy currents being set up at the points a, b and c. About eighty-six percent of the shrinkage has taken place at the time the ware enters division D. y

It will be seen that in these-three divisions, the shape of the roofs and floors need not be very accurately worked out, due to the fact that the shrinkage has mostly taken place,` the main object being to get as large amount of circulation as possible in these three divisions.

Tn division C I have provided the curved floors 32 and the curved portion of the iirst half of the roof 33. By forming the floor 32 on the curve of a hyperbola, I have provided means whereby air will be moved upwardly through the ware as it enters the compartment 33 at a fairly uniform velocity at all points of the ware. The curved roof portion ot the compartment 33 serves to force the air down through, the compartment. The same action takes place in the divisions B and A, the only difference being that the compartments A and B are longer than the compartment AC and the velocity through the ware is thereby reduced. It sometimes happens that it is necessary to provide extra moisture as the air enters the compartment 40. This I have accomplished by providingthe tank 43, which is supplied with water through the supply pipe 46.

Referring to the drawings illustrating the modified form of my device,it will be seen that the arrangement is substantially the same with the exception that Iv have pro-l vided beneath the lower compartments or divisions A, B, C, D and E a passageway for receiving the heated gases from the burnere at atmospheric tem-` colored and to go into chemical combinations which are more or less detrimental. By su plying heat through radiation, I have viated the above ditliculty.

The passage above referred to consists of an enlarged chamber 50 having a sheet metal plate 51 above it, which forms a bottom for a portion of the compartment 22 and for the compartments 26, 30 and 34. The passage 50 is in communication with a transversely arranged passage 52 which serves as an inlet supply passage. The opposite end of the chamber 50 is provided with a vertical wall 53, which serves as a support for one end of horizontally arranged pipes 54. The opposite ends of the pipes are mounted in a vertical wall 55. The space between the walls 55 and` 53 forms a chamber 56 beneath the

compartments

39 and 40. The pipes 54 communicate with the exhaust passage -16 and the ends of the pipes that are mounted in the wall 55 are lower than the ends which are mounted in the wall 53, so that any con densation of moisture that may be formed 1n the pipes 54 will run into a trough 57 provided for that purpose.

The practical operation of the modified form of my device is as follows:

Assuming that ware is placed'on the con veyor 12 and is being moved through the kiln, either continuously or intermittently, air will be drawn through the kiln irst through the passage 17 and longitudinally through the kiln in the manner described in my preferred form..v and exhausted through the passage 16. This air will be, for illusrtraion, at a temperature of one hundred degrees, and taken directly from the outside atmosphere. If the kiln is in continuous operation, the ware will be heated to a temperature of probably 24Q-or 250 degrees, and as it advances through the kiln from the left to the right, as illustrated in Figures 5 and 6, the air which passes upwardly through the ware from the passage 17" will have a tendency to bring the wareto the temperature of the incoming air, and the air will thereby he heated, and as it passes through, the compartment 22 beneath the roof member 21 it will be brought to a temperature of about degrees, and will from there pass-into the compartment 23 located above the passage 52. The gases of about 300 degrees orv ipso wardly, raising the temperature of the air to about 240 degrees, which will then gradually be cooled as 1t is advanced through the kiln in about the ratio illustrated in the various compartments.

As the heated gases in the chamber 30 pass backwardly the heat will be radiated through the plate 5l to the compartments above, and when it has reached the tubular members 54, the temperature will probably be reduced to about 150 degrees. The air which is taken through the inlet 52 may be derived from the chimney of the kiln which contains a large percent of moisture, sulphuric acid and other gases which are injurious to metal when the temperatures of the gases have been reduced to a point where condensation takes place and would be injurious to a thin sheet metal plate. For that reason I have provided the tubes 54 formed of cast iron or any other suitable metal which is not so easily acted upon by the objectionable gases. After further radiation takes place andthe condensation of the moisture and gases is permitted until substantially the total amount of heat has been extracted from the air and also the latent heatv of the moisture.

It will be seen by this arrangement that I have provided means whereby a comparatively large amount of heat `may be derived or the purpose of drying the ware from exhaust gases which would otherwise be wasted.

By providing the chambers 50 and 54 with means for conducting the Waste gases through them, the heat of the same being radiated to the compartments above, I have provided means whereby the temperature of the wastegases may be lowered at that point,`whereby the latent heat may be utilized for heatmg without being detrimental to the ware. through the kiln as outlined by the arrangement illustrated in Figures l, 2 and 3 of the drawings, the condensation would form on the ware and be very detrimental, due to the fact that instead of drying the ware, it would have a tendency to meisten it, and as far as I am aware, it has never been custom ary to reduce the temperature of the drying air to a point where condensation of the moisture would take place in the kiln to any great extent.

Thus it will be seen that the modified form has the advantage of utilizing a greater percent of the heat from the exhaust gases which are originally supplied with moisture for the purpose of drying the ware.

It will further be seen that it also provides means for supplying the drier with pure air which will keep the ware in clean condition for burning, so a better color may be imparted to the Ware when burned. The

If heated air vwas carried f condensed luid may be drawn from the trough 57 and treated as a by-product to l produce sulphur andthe like which results in further economy in o eration.

Thus it will be seen t at I have provided a drier ofk comparatively cheap and inex pensive construction, and yet one which is so arranged and constructed that air may be continuously passed through it and dried at a maximum speed without cracking, breaking or warping the ware.

I claim as my invention:

1.. A drier comprising a tunnel designedv to receive plastic ware, the tunnel being provided with a series of upper compartments, means for moving a current of air through the tunnel from one end to the other, the roof of each of the upper compartments being provided with a horizontal portion and conveying ware centrally'through the tunnel from one end to the other, said tunnel being constructed to form a series of compartments above and below the ware, means for drawing air longitudinally through said tunnel, the roof of each ot the compartments above the ware being provided with a horizontal portion and a portion being formed on the line of a curve which approaches,

parallelism to the line ot' travel of the ware, a portion of the iloor of each of the lower compartments being formed horizontally, a portion of which isgformed on the line of a curve which approaches parallelism to the line of travel of the ware, said curved portions being designed to cause said air to be forced through the ware in alternate directions.

3. In a drier of the class described comprising a tunnel, means for moving ware through the tunnel from one end t'o the other, means for supplying heated air to one end of said tunnel and removing it from the opposite end, the air being designed to move in an opposite direction from the movement of the ware, an auxiliary moisture supplying tank situated near the inlet end of the tunnel, and means for supplying additional heat to the said auxiliary tank other than that which would be supplied by the heated air of the kiln.

4. In a drier of that class that is adapted to receive and dry plastic ware by passing a current of heated air over the ware, an auxiliary moisture supplying means for the drier situated at a point near to where the air is being taken from the drier.

. 5. A drier comprising a tunnel designed to receive a moving row of plastic ware, the tunnel being divided into a series of above and below the ware set in staggered relation to each other and designed to pass formed on a the air throu h the ware in reverse directions, means esigned to moveI the air in an opposite direction romthe travel of. the ware, those compartments next to the .inlet end being longerthan those at the delivery end of the kiln, for the purposes stated.'

6. A drier comprising substantially a tunnel designed to receive plastic ware, the tunnel being provided with a series of upper and lower compartments, means for moving a current of air through the tunnel from one end to the other, the roof of each of the upper compartments being provided with a horizontal ortion and a portion being line of a curve which approaches parallelism to the line of travel of the ware as it nears the final air delivery end and which curved, ceiling forces the air .downwardly through the Ware, the lower compartments being arranged in staggered relation with the upper compartments and provided with portionsof its ioor formed horizontally and a ortion bein formed on a line of a curve w ichapproac es parallelism to the line of travel of the ware as it nears the nal air delivery end, and which curved Hoor forces the air upwardly through the ware.

7 A drier comprising substantially a tunnel designed to receive plastic ware, the tunnel being provided with a series of upper and lower compartments, means for moving a current of air thro-ugh the tunnel from one end to the other, the roor` of each of the upper compartments being provided with a horizontal portion and a portion being formed on a line of a curve which approaches parallelism to the line of travel of the ware as it nears the final air delivery end and which curved ceiling forces the'air downwardly through the ware, the lower compartments being arranged in staggered relation with the upper compartments and provided with ortions of its floor formed horizontally and a portion being formed on a line of a curve which app-roaches parallelism to the line of travel of the ware as it nears the final air delivery end, and which curved iloor forces the air upwardly through the ware, the curved portions of the roof bein opposite the horizontal portions of the oor and the curved portions of the floor being opposite the horizontal portions of the roof.

8. A drier kiln comprising substantially a tunnel .adapted to receive ware located midway between the top and the bottom,

` means for moving air through the tunnel from one end to the other, said tunnel being provided with a series of upper and lower compartments arranged in staggered relation' with each other, said compartments be,-

ingI so shaped and formed that air will be 'moved through the ware at the dry end of the kiln at a comparatively high velocity and at the opposite end of the kiln at a comparatively low velocity, the said compartments being also so arranged that the high velocity will produce eddy currents for the. purpose of producing a large amount of recirculation, while the air at the low velocity end of the kiln will be caused. to

move uniformly through the ware.

9. A drier comprising substantially a tunnel adapted to receive ware that is moving through the tunnel from one end to the other, means for moving air through the tunnel in opposite directions to the movement of the ware, the walls of the tunnel being so constructed that the 'velocity of the air will be lowest at .the point in the kiln where the shrinkage is the greatest.

10. A drier comprising substantially a tunnel designed to receive plastic ware as it is adapted to be moved from one end of the drier to the other, means for introducing and moving fresh air through the drier from one end to the other, means for introducing a heat bearing medium at a point between the intake and discharge ends of the drier, the said medium being arranged to radiate heat to the drier from its point of introduction to its point of discharge.

l1. A drier comprising substantially a tunnel, means for moving plastic waie longitudinally through the tunnel from one end to the other, means for introducing air to the delivery end of said tunnel and taking it from the intake end, means for introducing and maintaining a current of heated air adjacent to oney side of the kiln in such a manner that the heat from the said heated air will be radiated to the tunnel, the point of introduction being between the inlet and outlet end of said tunnel, and the point of removal being at the inlet end, substantially as described and for the purposes stated.

12. A drier comprising a tunnel having upright side walls parallel with each other,

means for conveying ware centrally through the kiln from one end to the other so as to form a series of compartments above and below the ware, the compartments above the ware being in staggered relation and in coinmum'cation with those below the ware, and means for drawing air longitudinally through said compartments so as to cause the air to travel through the ware in alternate reverse directions, the compartments below the ware being provided with a heat conductive floor, a passage beneath the said floor, the said passage being of a length less than the length of the tunnel, and means for introducing heated air to one end of said passage and removing it from the opposite end.

13. A drier comprising substantially a 4tunnel provided with means for moving ware through it from one end to the other, mea-ns for moving fresh air through the Ware in a direct-ion opposite to that in which the ware is moved, a passageway located longitudinally adjacent to one side of the tunnel and adapted t0 receive heated moisture bea-ring gases at a point inside of the disradiate heat therefrom as it is a vanced 10 through said passage, for the purpose of heating the air Within the tunnel, substantially as described and .for the purposes sta-ted.

Des Moines, Iowa, January 12, 1924.

HALVER R. STRAIGHT.