A FEEDING DEVICE FOR HIGH PRESSURE DIGESTORS

Abstract: The present invention refers to a feeding device for high pressure digestors of the type comprising a feeding assembly (1) that comprises a conical tubular body (6) having an inlet nozzle (9) and an outlet nozzle (10) mounted on a structural base (7) and a threaded axle (11) received inside it, said threaded axle (11) being driven by a motor (2), a reducer (3) and a speed variator (4) through a first end (14) and having a free opposed distal end (13). Right below said inlet nozzle (9), said threaded axle (11) is provided with a rectilineal stretch (16), in which said helical channels have a homogeneous depth (12a) to facilitate the gripping of the material. Further, the distal end (13) of said threaded axle has a conicity (17) corresponding to the conicity of said tubular body (6), the depth (12b) of the helical channels at said distal end gradually decreasing along the length of the axle, so as to expel the material and compress it against the inner surface of the tubular body.

Description: Title: "A feeding device for high pressure digestors" Technical Field The present invention refers to a feeding device for use in general and, more specifically, to such a feeding de- vice particularly designed for use in a high pressure digestor, so as to feed, in a continuous and homogeneous man¬ ner, lignocellulosic organic material into said high pressure digestor. Background Art Feeding devices for introducing raw material into an equipment for carrying out industrial processes, such as, for instance, for feeding a lygnocellulosic organic material into a digestor, are widely known from the state of the art. These feeding devices, which usually comprise a threaded axle driven by a moto-reducing assembly, are intended to feed the lignocellulosic material in a continuous and homo¬ geneous manner into the digestor, while at the same time re¬ ducing the size of the fibers of the material down to an adequate granulometry, decreasing the moistness contents and compressing the material so as to facilitate its dissolution when in contact with the liquor. Typically, the digestors utilized today in the state of the art develop an inner pressure on the order of about 16 Kg/cm 2 in its reaction chamber. Although this pressure is con¬ trary to the feed pressure, this does not represent any prob¬ lem as far as the continuous feeding of the lignocellulosic material is concerned, since the feeding devices provided are perfectly capable of resisting to a counterpressure of this order. In the last few years, however, digesting equipments have been developed for work under conditions of greater ad¬ versity, which operate with high inner pressures, in the order of approximately 40 Kg/cm 2 , and at temperatures ranging from 160 to 250° C, for which reason the feeding devices for these high pressure digestors should be capable of providing a con¬ tinuous and homogeneous feeding of the lignocellulosic mate¬ rial, while resisting to a counterpressure of this order. Disclosure of Invention Therefore, there is the need to provide a device for feeding lignocellulosic material for a high pressure digesting equipment, which is capable of resisting to a counterpressure in the above-specified order, which is one objective of the present invention. Another objective of this invention is to provide such a device for feeding a lignocellulosic material into a digestor equipment capable of resisting a counterpressure in the above-specified order, while providing a continuous and homogeneous feeding of the lignocellulosic material. According to the present invention, these objectives are achieved by the provision of a feeding device for high pressure digestors of the type comprising a feeding assembly that comprises a conical tubular body having an inlet nozzle and an outlet nozzle mounted on a structural base and a threaded axle received inside it, said threaded axle being driven by a motor, a reducer and a speed variator through a first end and having a free opposed distal end, in which right below the referred-to inlet nozzle said threaded axle is pro- vided with a rectilineal stretch, in which said helicoidal channels have a homogeneous depth to facilitate the gripping of the material, and by the fact that the distal end of said threaded axle has a conicity corresponding to the conicity of said tubular body, the depth of the helicoidal channels in said distal end decreasing gradually along the length of the axle, so as to compress the material. Best Mode for Carrying Out the Invention With reference now to the drawings, a feeding device for high pressure digestors in accordance with the present in¬ vention is illustrated in figure 1, basically comprising a feeding assembly 1, driven by a driving assembly constituted by a motor 2, a reducer 3, a speed variator 4 and a coupling 5 interconnecting the driving assembly with the feeding assem¬ bly. The referred-to feeding assembly 1 is made up of a conical tubular body 6, fixedly mounted on a structural base 7 through lower supports 8, and by a threaded axle 11 placed in¬ side the referred-to conical tubular body. The conical tubular body 6 is provided with an upper inlet 9, to which a conical feeding hopper is coupled, and with a lower outlet 10, formed at the distal end of said body 6, through which the lignocellulosic organic material is fed into said feeding device and discharged into the digestor. Said threaded axle 11 is provided with helical chan¬ nels 12 along its length, which are intended to draw the lignocellulosic material inside said conical tubular body 6. A first end 14 of said threaded axle 11 is supported on a roller bearing 15 and passes through the corresponding end of said conical tubular body 6, so as to be connected to said coupling 5 and, through the latter, to the driving assem¬ bly constituted by the motor 2, the reducer 3 and the speed variator 4, while the distal opposed end 13 of said threaded axle is free inside said conical tubular body 6. The speed variator 4 is intended to provide an accu¬ rate control over the rotation of the threaded axle 11, so as to facilitate the holding of a larger or lesser amount of lignocellulosic material for feeding the digestor, depending upon the needs of the process. According to the present invention, the threaded axle 11 has a rectilineal portion or stretch 16 right below the inlet 9, in which the helical channels present a uniform depth 12a, so as to facilitate the gripping of the material from said inlet 9. Still according to the present invention, the free distal end 14 of said threaded axle has a final portion or stretch 17 also slightly conical, so as to correspond to the conicity of said tubular body 6, in which the depth 12b of said helical channels gradually decreases so as to compress the material being fed. A threaded axle 11 with a constructive arrangement as described above permits a better gripping of the material being fed into it through the inlet, owing to the even depth 12a of the longitudinal channels in said rectilineal portion or stretch 16 of the threaded axle. Further, the gradual reduction of the depth 12b of said helical channels at the free distal end 14 of said axle gradually urges the material drawn out of them and against the inner wall surface of the conical tubular body 6, thus com- pressing the material against it. The above preferred embodiment of the present in¬ vention having been described and illustrated, it should be understood that many modifications and/or alterations will be promptly apparent to those skilled in the art, and that such modifications and/or alterations should be understood as being within the spirit and scope of the invention, as defined in the accompanying claims.

Claims: Claims 1. A feeding device for high pressure digestors of the type comprising a feeding assembly that comprises a con¬ ical tubular body having an inlet nozzle and an outlet nozzle mounted on a structural base and a threaded axle positioned inside it, said threaded axle being driven by a motor, a reducer and a speed variator through a first end and having a free opposed distal end, characterized in that right below said inlet nozzle, said threaded axle is provided with a rectilineal stretch, in which said helical channels have a ho¬ mogeneous depth to facilitate the gripping of the material, and that the distal end of said threaded axle has a conicity corresponding to the conicity of said tubular body, the depth of the helical channels at said distal end gradually decreas- ing along the length of the axle, so as to expel the material and compress it against the inner surface of the tubular body. 2. A feeding device in accordance with claim 1, characterized in that said feeding assembly 1 comprises a con¬ ical tubular body fixedly mounted on a structural base through lower supports and an innerly threaded body received inside said conical tubular body. 3. A feeding device in accordance with claim 2, characterized in that said conical tubular body is provided with an upper inlet, to which a conical feeding hopper is cou- pled, and with a lower outlet formed at the distal end of said body. 4. A feeding device in accordance with claim 1, characterized in that a first end of said threaded body is supported on a roller bearing and passes through the corre- sponding end of said conical tubular body, so as to be inter¬ connected with said coupling and, through the latter, with the driving assembly comprising the motor, reducer and speed variator, while the distal opposed end of said threaded axle is free inside said conical tubular body.

Inventors: PROENCA HILST ANTONIO GERALDO, PROENCA HILST, ANTONIO, GERALDO
Applicants: DEDINI S A ADMINISTRACAO E PAR, PROENCA HILST ANTONIO GERALDO, DEDINI S/A ADMINISTRACAO E PARTICIPACOES, PROENCA HILST, ANTONIO, GERALDO
Application year: 1996
Main classification: D21C7
IPC codes: B01J3, B65B37, B65G33, D21C7