DE1946696A1 - Process and device for accelerated drying of plasterboard - Google Patents

Description

1946695

MOORE DRY KILN GOMPAHY OF OREGON
ITORIH PORTLAHD, OREQOIT 97 043, V.ST.A »

The invention relates to a method and a device for accelerated drying of plasterboard and similar mineral products with excess moisture is removed from a moving belt of a wet, manufactured material by means of the controlled application of a heated one air medium. In particular, the invention uses one insulated drying chamber, which has a large number of fan nozzles, which air with high temperature at extremely high Align the speed so that it is at right angles to the top and bottom of the moving horizontal Tape of plasterboard hits »by the exemplary embodiment of the invention disclosed herein relates to the drying of plasterboard, wherein a layer is formed of wet plaster of paris and a composite binder first layered and wrapped within a paper wrapper Then it is dried, it is understandable that these teachings also apply to an accelerated treatment of mineral tablets or other similar materials, for example lime, Paris mortar, clay, asbestos, etc. can be used, with together with suitable binders, which are added for strength and stability, in strips or plates.

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are shaped and then subjected to drying or heat treatment get abandoned·

A plasterboard, often referred to as a wallboard, comprises a layer of plaster of paris and binding material that while wet is first wrapped in a paper cover and then dried to achieve the end product. The size The dimensions of the plasterboard or wall panel are divided into 4 x 8 panels of running four-foot-wide ribbons cut, the side edges of which are beveled for purposes of building construction are on a bevel that starts about 1-1 / 2 inches from the edges.

Conventionally, the methods for drying plasterboard material use simple or multi-tier systems in which a heated air flow circulates through the drying chamber in the longitudinal direction, that is, parallel to the direction of movement plaster of paris tape or tapes through the system. In these known systems, the flow of flow is at the interface of the panels always horizontally and parallel to the direction of the belt. Typically, such systems include several isolated ones Tempera door zones, each with a region different Ambient temperatures to remove excess moisture of the gypsum product forms *

Due to the great length of these earlier systems (20 - 45 m Length) together with the long airflow circulation paths

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within the individual chamber zones it is very difficult to get into Achieve moisture uniformity in the resulting product. Especially due to the length of the airflow figures there is a considerable drop in temperature from the point on the inlet side of the chamber where the heated air enters, to the outlet side, where the air exits.

To reduce the size of the drying systems and the drying process To accelerate, attempts have been made to reduce the temperature of the drying medium at the inlet side of the Raise the drying chamber somewhat so that the air flow, although it is cooled considerably after it has passed the length has passed through the chamber, still has a sufficient temperature level for effective drying. However, the application has of strongly heated air at the relatively narrow entrance area of the drying chamber often results in an overdrying condition generated in the thin, beveled edges of the plasterboard. If on the other hand the inlet temperatures decreased in order to prevent damaging edge softening, the central part of the panel is often insufficiently dried and sufficient excess moisture remains in the moist central portion to make the panel unacceptable as a commercial product to appear. The limitation of the inlet temperature level together with a considerable cooling, which results when the drying medium moves along the path through the drying chamber make it required that the plasterboard tape either proportionately

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progresses slowly through the dryer or that the chamber is very long in order that the residence time of the plaster of paris is adequate for sufficient drying to be achieved target. In order to achieve acceptably high production speeds (0.5 m / Seik,), it is with conventional systems at a drying chamber is necessary, which typically comprises three or more separate longitudinal air flow zones that they extend 110 m or more extends.

Due to the critical circumstances involved in balancing the drying environment over the entire length of the drying chamber are required so that the central and end portions of the plasterboard are dried to an even moisture content the existing systems cannot normally perform consistently over a continued one accelerated production line. The result consists in the fact that with the known systems a considerable part of the plasterboard production cannot be used Construction purposes due to uneven drying and must either be considered waste or shredded to serve as a backing for transportation supplies to protect.

From the above it follows that the problems with soft edges and wet middle parts, the occur during the drying of the gypsum boards by means of known systems, basically on the serious temperature

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Gradients based on the longitudinal flow path of the heated Air medium is generated, which moves parallel to the movement of the sheet material through the drying chamber. Also due to the relatively low air temperatures and speeds used will remove the moisture from the board removed very slowly and therefore a drying chamber of considerable length is required to provide adequate residence time of the material in the dryer at the production speed.

The novel gypsum dryer design of the present invention provides a faster and more consistently controlled one Removal of moisture from the wet plasterboard band effected by the application of a large number of high-speed air nozzles, which are arranged at a distance from one another via the drying chamber and a strongly heated air stream Point perpendicular to the surfaces of the plasterboard strip · For a corresponding production speed, the total length the drying chamber can be significantly reduced compared to conventional constructions due to the more effective moisture removal, which is made possible by the nozzle drying effect. Furthermore, the orbits are for the warmed Airflow arranged in vertical planes rather than parallel to the longitudinal direction of the board movement, creating a greatly reduced path length for the air flow and an approximately constant temperature environment over the entire length of the Drying zone

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The flow nozzles are arranged so that they direct the air against the top and bottom of the moving horizontal plaster tape, and though they are over the drying chamber are distributed, they have a reduced at the locations of the opposite edge regions of the tape Number to prevent overdrying of these thin, critical areas.

In general, the invention discloses a compact, multi-layer, continuous gypsum dryer comprising an isolated multi-zone drying chamber in which a heated air drying medium is passed through a plurality of staggered flow nozzles at a high temperature (150-550 ° C) and a high speed (12-50 ° C) m / sec ·) so that it strikes perpendicularly against the corresponding main surfaces of a moving plasterboard strip. «After hitting the plasterboard, the drying medium reverses laterally to the direction of movement of the plaster of paris material and then circulates in relatively short closed loops, which lie in planes perpendicular to the longitudinal direction of the belt movement. The flow nozzles, although they are distributed over the entire width and length of the plaster of paris tape going through the chamber, have a compression in the middle area of the tape in order to prevent overdrying of the edges of the plasterboard The drying medium on the plaster tape is reached via the I-reite through a lateral bevel & sv ^ flow-

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nozzle air boxes and by an alternating direction of the side Circulation flow in the successive drying zones

In an “exemplary embodiment” described herein, the invention of the 3-shape of a multi-zone, eight-deck dryer, the eight floors of the plasterboard band through the isolated drying chamber by means of a horizontal roller conveyor to be driven. The drying air medium is heated directly in the corresponding zones by a large number of Gas burners set to various temperatures within the range of 150 - 550 ° C and circulated through appropriate Sets of fans mounted on top of the drying chamber and arranged so that the air flow in a Circulating series of short, closed loops arranged across the direction of panel movement. The airflow speed through the flow nozzle system is maintained uniformly along the width of the chamber through the application of inclined air bolts, and the direction of the lateral air flow is determined in the successive zones of the drying chamber conversely, as a means of further removing any irregularities or bumps in the panel moisture content to reduce"

It is therefore a primary object of the present invention to provide a novel method and apparatus for an improved one accelerated drying of plasterboard and similar mines

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- to make 8 ral products available.

Another important object of the present invention is in a novel method and device for producing dried plasterboard, with a more uniform Drying and moisture content control can be achieved with minimal overdrying of the edges or insufficient drying of the middle parts of the material.

Still another object of the present invention is to reduce the size and length of the high speed continuous gypsum board dryer to be reduced considerably by the application of heated air currents of temperatures and velocities, which significantly exceed the values previously applied.

It is a key feature of the present invention that drying of the plasterboard is effected through the use of Jet airflows of high speed and high temperature, those directly perpendicular to the corresponding major surfaces of the moving strip material are directed.

Another important feature of the invention is that a heated air stream, which is used for drying the plasterboard tape, circulates in closed tracks of relatively short length, the tracks being arranged in planes which are perpendicular to the longitudinal direction of the tape.

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- 9 "movement run.

Yet another important feature of the invention is the provision of an inclined construction for the laterally arranged flow nozzle air chamber sections, by means of which the heated air currents are maintained at a uniform rate across the width of the plaster of paris tape.

A major advantage is that the high speed plasterboard continuous drying system of the present invention high quality gypsum boards with a controlled and uniform moisture content produced in accordance

The foregoing as well as other objectives, features, and benefits of the present invention should become apparent from the following description of an exemplary embodiment with reference to FIG the attached drawings show »In the drawings:

Pig, FIG. 1 is a partial plan view of an embodiment of FIG drying system according to the invention, part of the length of the drying chamber can be seen;

Pig · 2 is a front view of that shown in Pig Drying chamber;

Pig x 3 is a sectional view through the drying chamber along the line 3-3 in Pig x 2;

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1346696

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J ¹ Ig * 4 is an enlarged sectional view with parts broken away to show a portion of the drying chamber shown in FIG. 3;

Fig. 5 is a top plan view taken along line 5-5 in Pig · 41 the arrangement and location of the flow nozzles in one of the air chamber modulator sections of Represents drying plant;

Pig, 6 is an enlarged view of the flow nozzle con-. structure and the course of the air flow at the point of the Hitting the plaster of paris tape; and

Pig, 7 a perspective partial view in greatly enlarged Scale a portion of a set of the respective air can modular sections, where the air flow over the area of the plaster of paris tape is shown schematically «

In the drawings, particularly in Pig · 1-4, is a Gypsum dryer system shown, according to the teaching of the present Invention is constructed. The dryer system includes a thermally insulated chamber, indicated generally at 10, which is a typical embodiment about 15 two meters long Modular sections, which are generally the same, are 7 Sections, as they are designated by 12a ·· »12g, with one Total length of about 30 m comes out »The working process is as follows · The damp grip board material, after which a prepared conventional drying is carried out in the

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Form a tape up to 72 m in length to the chamber inlet fed into Mg · 1 and 2 on the left. The material moves horizontally through the chamber 10 to the right, exiting it in a dry state after it has passed through a number of modular sections 12a ... 12n connected in series.

For example, as best shown by the cross-sectional views of Pigs 3 and 4, which show a typical modular chamber section 12f, the drying chamber is designed to treat eight areas of plasterboard tape, and the chamber is wide enough to accommodate two four- To guide foot-wide belts close to one another, so that overall the dryer system has a capacity for a simultaneous processing of 16 four-foot-wide belts of plasterboard material. Each of the belts 15 is passed horizontally through the core of the drying chamber 10 by a conventional roller conveyor 18 which is driven by associated side-mounted sprocket assemblies 19 from a respective motor with transmissions (not shown). The multi-tier conveyor 18 and associated drive 19 are supported within the core of the chamber by a box-like framework comprising horizontal members 20,21 and vertical supports 23,24.

The inner shaft opening, through the floors of the plasterboard strip are advanced through the chamber portion surrounding a

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C-shaped passage 30, which together with the chamber shaft forms a round path for closed circulation of the drying medium. The flow path of the air within the Chamber section, as shown schematically by the arrows in Figure 3, runs as follows «First the air pressurized by a turbo blower 38 driven by an associated belt drive motor 39 · Then will bring the air to the appropriate temperature in the range of 150 to 550 ° C by a burner 35 which is charged with gas from a pressure pipe source (not shown) via the pipe network 36a ·. »36h is supplied · After heating, the Air through the fan above the chamber sideways and then down into the left vertical section 30a of the C-shaped Pushed through · As can be seen in particular from Pig · 4 and 5, the heated air then goes into the corresponding Inlets of a variety of laterally extending hollow, right-angled air chambers 40, which are associated with the respective floors of the conveyor 18 · The heated air then exits the air chambers at high speed through a multiplicity of flow nozzles 42, which are distributed in a staggered arrangement over the top and bottom (as shown in FIG 4 shows, the corresponding top and bottom air chambers in the tier arrangement only have flow nozzles 42 on one their surfaces, while the air chambers in between are provided with nozzles on both main surfaces «)

As shown schematically in FIGS. 6 and 7, the

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Heated air from a single flow nozzle 42 at a holier speed, typically at 12-50 m / sec _# , to impinge on the horizontal surface of the moving grip tape 15 at right angles. The high-speed, high-temperature jet action produces an efficient and rapid drying of the damp gypsum board material, and due to the divergence of the boundary layers, which is due to the hard, rectangular shape. If the jet stream hits the flat surface of the belt, the drying effect is to a large extent perfect. The high air temperatures used, which are considerably higher than the conventional temperatures selected for gypsum dryers, are not harmful because the moisture is removed very quickly Interior of the plaster of paris material is removed and rapidly evaporated from the surface, thereby providing a cooling effect that protects the panel from damage or adverse discoloration,

Hachjdem to meet, is applied to the Gypsum Belt material _(# in FIG. 3by right) deflected air flow laterally across the surface and discharged from the shaft area in the right vertical portion 30b of the C-shaped passage and afterwards pushed up to the inlet side of the turbo fan 38, to complete the circulation path * The moisture is carried away by the gypsum material in the drying process and is accumulated in the gaseous medium which is expelled to the atmosphere through the exhaust duct 45.

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tion of the drying, gaseous medium at the critical one Point where the nozzle stream 41st on the surface of the plaster of paris tape 15 on meets is schematically detailed in Pig · 6 and in perspective shown in Pig x 7.

As the arrow heads reflect, after the impact of the Jet stream, now the vaporized! Moisture containing, the flow is diverted laterally to the right to the exit from the shaft area of the chamber. TJm a steady speed Each air chamber 40 is to maintain the air flow 41 »emanating from the corresponding flow nozzles beveled inward along its length so that the cross-section is reduced while maintaining a pressure that is constant as the incoming air flow is deeper flows into the air chamber. Like Pig. 7 shows is in such As the air flow progresses from the left side or the inlet side, gradually following each of the air chambers 40 inside inclined to a reduced cross-section. This beveled air chamber shape serves to reduce the resulting To keep the outlet flow velocity constant over the lateral length of the air chamber cross-section, and in such This avoids the possibility of any uneven drying along the width of the plaster of paris tape. To the side Inner chamfering of the air chamber sections 40 away from the plane of the plaster of paris strip material 50 to compensate for a constant flow rate at the point of impact to maintain the material, it is advisable to use the

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To provide flow nozzles 42 with a gradually increasing axial length, according to their position, as they are away from the inlet side of the air can "

As mentioned earlier, one of the significant advantages is the present Invention of the rapid drying process made possible by the use of high speed and jet streams high temperature is achieved, the. Currents are directed at right angles to the plane of the moving plaster tape, TJm, however, to prevent the thin, beveled end edges of the plasterboard from drying out too much, which is detrimental leads to so-called "soft edges" is the density of the flow nozzle grouping in the parts of the chamber sections which are opposite the edges of the plasterboard strips, so that the drying effect along the edge bands of each area is considerably reduced. So is how the top view according to FIG. 3. FIG. 5 shows an evenly distributed, staggered arrangement of the flow nozzles 42 over the parts of FIG Air chamber area, which is the major part of the side surface of the two adjacent plaster strips «This central strip corresponds to about 85 - 90 56 of the plate surface where the Layer of uniform thickness is «However on the edge bands on either side of the two plaster bands is the number of Nozzles that direct currents directly against the ribbon edges, greatly reduced in order to prevent excessive drying out «(Hit 43 is not a nozzle, but a central support pillar for the hollow air chamber section.)

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As already stated, there is a typical gypsum drying plant of additional modulating chamber sections 12 in addition to the seven shown · In a typical installation About 15 of these modulating chambers are connected in series, so that the resulting drying chamber area has a total length of about 30 m · The ambient temperature in the drying chamber is not over the entire length kept constant, as is known, instead a division into three or four zones of different temperatures is used intended to optimize the moisture removal process and hardening of the material · Thus, in the Overall chamber system, as shown in Figures 1 and 2, the seven modular sections 12a ··· 12g in two temperature zones with different drying environmental conditions divided into it «They sections 12a ·, .12c comprise the first zone, and the remaining four sections 12d "" "12g serve as second zone, each of the zones under the appropriate environmental conditions is held by associated control devices (not shown).

A key feature of the present invention is that the direction of the lateral airflow of the drying medium Over the surface of the plaster of paris tape is reversed in successive temperature zones «In such a way as by the Arrows shown in plan view of Pig · 1, the air flow is in the first temperature zone, which the chamber sections 12a "."

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to the top, which results in a cross-circulation flow over the faces of the stacked plasterboard strips, which flows from a right-hand end view seen from right to left or clockwise runs inwards »In the second temperature zone, the Chamber sections 12d »». 12g, however, is the direction of the current vice versa, so that the lateral cross-circulation air flow crosses the surfaces of the stacked strips from left to right or counterclockwise, as shown in Fig. 3, traversed. This reversal of the transverse direction of circulation is practically eliminated any inaccuracies in the drying process across the surface of the panel by compensating for any gradient effects due to the cooling or moisture saturation that would otherwise be present when the drying Would swipe the medium sideways over the tape "

From the above description in connection with the schematic representations of the air flow circulation it can be seen that, in contrast to conventional drying systems, in which the air flow flows through the chamber parallel to the longitudinal movement of the belt, the air flow in the present scheme follows a lateral circulation path of very short length thereby greatly reducing the size of any temperature or humidity gradient in the drying medium "This greatly increases the efficiency of the drying process and the actual speeds of the drying of the gypsum board materials, wherein any Unregelaäfligkeiten or üngleichmäöigkeiten in the

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Moisture content of the finished panel product to a
Minimum to be returned *

In contrast to previously used plasterboard dryer systems, a multi-story dryer system constructed in accordance with the teachings of the present invention and recently installed
and now works satisfactorily by adding 16 bands -of
four-foot-wide (ripstafeln on a continuous production line at a speed of 33 m / sec. are treated with a far better quality control than
in a conventional drying kiln requiring an additional $ 40 in length for the same production capacity

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Claims (1)

Claims e Process for the heat treatment of flat strip material with a constant, but laterally non-uniform cross-sectional thickness, characterized in that the material is controlled in the direction of its belt length through an area Environment is moved that the material in the area of a plurality of nozzle streams at high speed and exposed to high temperature and that the currents are approximately perpendicular to the major surfaces of the moving belt are directed, the number of nozzle streams that are directed against the relatively thinner cross-sectional parts of the Material is less than the corresponding number of jet streams impinging on relatively thicker cross-sectional parts of the material as it passes through the area in question is moved. 2. The method according to claim 1, characterized in that the corresponding speeds and temperatures of the nozzle streams .within a predetermined lateral strip in the treatment area all are kept roughly the same " 3. · Method according to claim 1 or 2, characterized in that the material to be treated is in the form of a plasterboard strip with beveled side edges " 009818/1180 4 · Device for accelerated drying of flat material, with a longitudinally extending thermal insulation Chamber is provided, through the length of which a shaft runs, wherein a drive device the. Material moved horizontally through the shaft, characterized in that that a plurality of nozzles is provided in a distributed arrangement over the chamber, that the nozzles with a source of heated pressurized air in communication with flows of high temperature and high velocity air approximately perpendicular to the main surfaces of the through the Shaft to direct moving material, and that the material to be treated a uniform change in its Has cross-sectional thickness transverse to the direction of movement through the chamber and a reduced number of nozzles the thinner Is assigned to cross-sectional areas so that a uniform heat treatment of the material takes place, 5. Device according to claim 4 »characterized in that the material is a plaster band with bevelled edges is and that a reduced number of nozzles are provided in the longitudinally extending strips which the corresponding beveled edge areas of the plasterboard material are opposite, $, Device according to claim 4 or 5, characterized in that that the chamber has the 3? form of a multitude of modulating sections 0 0 9 8 18/1180 th has that at least one laterally extending hollow air chamber is connected to each of the modulating sections which is arranged transversely to the manhole opening in the vicinity of the material and at one end with a source heated compressed air in communication that each air chamber is provided with a plurality of nozzles that distribute are arranged above a horizontal surface in order to direct air currents perpendicular to the main surface of the material direct and that a compensating device is provided to a uniform pressure across the lateral extent the air chamber to maintain the speed to adjust the air currents emanating from the nozzles « 7. Device according to claim 6, characterized in that the compensating device consists of an inclined Air chamber exists, so that there is a gradually decreasing cross-section when the compressed air is inwardly from Inlet end of air chamber flows " 8. Device according to one of claims 6 or 7, characterized in that each modulating section is assigned a transversely running »laterally extending air chamber with flow s du sen, a compressed air device, a compressed air heating device and an additional chamber with a first part which is heated Compressed air connects to the inlet of the air chamber, and a second rope that 0 0 9 8 18/1180 194669S the air flow exiting from the duct area, after the Flows from the nozzles to direct the air flow to the pressure device for circulation through the corresponding Modulating section. 9 · Device according to claim 8, characterized in that the circulating path of the air flow within the corresponding Modulating section lies in an approximately vertical plane that runs transversely to the shaft " 10 «device according to claim 9, characterized in that the air flow in at least one of the respective modulating sections after hitting the material laterally flows over its surface in the opposite direction than that corresponding air flows of the other modulating sections » 11 · device according to claim 9 or 10 _t characterized in that the air chamber of each respective Modulierabschnitts has a tapered shape to form a gradually reduced cross-section, when the compressed air flows inwardly from the inlet " Device according to one of Claims 8 to 11, characterized in that the additional chamber has the frame of an inverted TT and that compressed air and heating devices are provided in the central part above the shaft . 009818/1180 13 »Device according to one of claims 1-12, characterized in that that for a number of η layers of a flat material a multiplicity of modular sections are provided which form a longitudinally extending thermally insulating chamber that means the layers hold horizontally spaced from one another in the chamber and move through it that each of the modulating sections n + 1 laterally extending, hollow air boxes, which in a vertical stack transversely are arranged to the shaft and with respect to the layers are arranged therebetween, the between the Air chambers located in layers of material have nozzles on the upper and lower horizontal surface » 14. Device according to claim 13, characterized in that a connecting device is provided for each corresponding modulating section, consisting of an additional chamber with the shape of an inverted U, which comprises a first connecting part, which the heated compressed air leads to the corresponding inlets of the air chambers and a second connecting part, which leads from the shaft area picks up air flow emerging after ejection through the nozzles and returns it to re-pressurization and for reheating, whereupon recirculation takes place through the corresponding modulating section 00981 8/1180 15 · Device according to claim 13 or 14 »characterized in that the plane of circulation for the air flow within of each modulating section lies approximately in a vertical plane which is arranged transversely to the tunnel shaft. 16 _# Device according to claim 15, characterized in that the air flow in at least one of the corresponding modulating sections after hitting the material flows laterally over its surface in a direction opposite to that of the corresponding air flows in the other modulating sections 0098 18/1180