SE526216C2 - Wood chip drying chamber, comprises triangular shaped airing chamber enclosed by slanting boxes for raw material and dry material - Google Patents

Abstract

The chamber (5) is a triangular-shaped one enclosed by two boxes for the raw and dried material extending an angle relative to each other. The material is dried in batches in two ramp-shaped beds (1, 2) inside triangular-shaped airing chambers (51, 52). A triangular drying chamber for wood chips (3) or a similar material comprises two boxes extending an angle relative to each other, one box (41) containing the raw material (31) and the other box (42) containing the dried material (32). The material is dried in batches with a high moisture gradient and is present in two ramp-shaped beds inside triangular-shaped airing chambers which are pressurized using a flow of drying gas (11, 21). Dried material is mixed and its moisture content evened out in the box for the dry material.

Description

2 6 2 1 6 ra: '12 asus. = "= ° ': = -a -' 2 E" E .i. '.'. g -: "E-. zu: E. .š- .åxå 2 The invention is described below in connection with the fi gures, wherein figure 1 shows a section and figure 2 a plan of the device. Figures 3 and 4 show in plan alternative drying arrangements. Figure 5 illustrates in a temperature diagram a 2-step drying process Figures 6 and 7 show in detail section an embodiment of aeration spaces and box bottoms.

In reference to Figures 1 and 2, 41.42 denotes two box-shaped boxes for buffer storage of raw ice 31 and 31, respectively. dried ice 32. The boxes are inclined towards each other at the angle of inclination of the ice material 3 and enclose a section triangular drying chamber 5 for batchwise drying of preferably double fl ice beds 1,2. The beds are filled centrally from the top to embankments covering each with the chamber 5 congruently triangular and centered comfort room 51.52, pressurized with each drying gas fl fate 11.21. The desiccant gases are circulated within the chamber to contact with heating means 6 and dehumidifying means 7 via triangular side channels 53 in the karnmar hut and a ridge portion 54. in the final phase amounts to about 22% -6%. The material is mixed during the emptying of the beds and moistened to 13% for an increased residence time in the dry chip box 42.

A through fl fate of fl ice 3 through the device thus occurs. Raw ice deliveries are emptied in a load section 80 and illuminated via transport screw 8l to the top of the raw ice box 41.

From its bottom, the beds 1,2 are filled in batches with screws 82. Horizontal scrapers 83 flatten to the top of the dikes 1,2. The beds are emptied batchwise via transport screws 84 towards the top of the dry ice box 42. With a continuously operating scraper device 85 this is emptied against a process line 86 for pellet / briquette production. The scraper 85 engages the entire depth of the ice bed 32, which as a whole slides slowly downwards during said moisture equalization in the material.

The ice material is handled with short transport routes and is problem-free in that it can fall or slide freely after each shelter without being able to hang.

Advantageously, drying time is included, including heating and replacement time for the batches 1.2 to about 8 hours and for a three-ski operation of the production. The boxes 41,42 are dimensioned to accommodate more than three times the volume of the batches 1,2.

The raw ice box 41 is filled during the day and a one-day residence time for moisture equalization is achieved in the dry ice box 42.

The drying gas ions 11,21 leave the beds 1,2 substantially steam-saturated during the entire drying process, which enables very efficient drying processes. In a first alternative, dehumidification takes place in a conventional manner by changing the air, ie emissions of steam-enriched, hot air and intake of external air. The process requires a reasonably good product; asus. = "= '°: = -2 3 a ° =' -.- ° =. =" S "= .. = s' .s .. = :. as a high temperature heat source to give a process warming rate of the order of 0.9 kg of water / kwh led other alternatives in reference to fi gur 3 circulating drying gas fl fumes 11,21 after exit from the beds to contact with a pleated, heat-insulating diffusion surface 7 exposed to the outside air in accordance with my Swedish patent application 0302197-9. marginal loss of sensitive heat in the closed gas-driven drying gases.The drying process can be operated with a low-temperature Jâgkw / alternative heat source in register 50 ° / 60 ° and with an efficiency of 1.3 kg water / kwh.

In a third alternative in reference to Figure 4, a first bed 1 is dried at higher temperatures with a first desiccant gas driven in a closed circuit within the chamber in cooling, steam separating contact to a heat exchanger surface 67 and reheated to a subsequent heater 6. A second bed 2 dried at lower temperatures with a second closed drying gas fl desolate 21 in steam separating contact with a said diffusion surface 7 and a subsequent heating contact to the heat exchangerThis uses a high temperature, high quality heat source for the heater 6 extremely efficient with a process efficiency of about 2.3 kg water / . The process is illustrated in a temperature diagram in figur 5 with fl fates 11,21 circulated in temperature registers 76 ° / 56 ° resp. 46 ° / 26 °. 'With fl marriage work for drying gas fl fates 11,21 supplied by internal combustion engines 9 such as diesels, the drying process is managed above without either an external heat source or electrical installation for fans. If the total fan work is denoted by W, the engine / exhaust heat is approx. 2W, which is supplied via heater 6 to the first drying gas flow 11. In bed 1, incl. kt marriage work 2.5 W, which is transferred via the heat exchanger 67 to the second fl fate 21. 1 second bed 2 is converted incl. fl marriage work 3W.

The exhaust heat can be transferred indirectly via an exchanger or directly via mixing in the first drying gas t fate. An additional advantage is achieved by mixing exhaust gas in the drying gas and blocking mold growth, especially in the low temperature bed 2.

Exhaust gas flows into the first, fate, over fl deserts cooled to the second and further to the atmosphere via the dif- feration surface 7. r Pressure drop, drying gas fl fate and bed thickness in the beds 1,2 may be coordinated with each other so that the proportions between fl marriage work W / 2 and heat supply 2W resp. 2.5 W is maintained. Excessively high gas velocities must be avoided due to entrainment of dust from the beds. A suitable compromise is the following data regarding a sqm bed area. .

Bed thickness 1.8 m. Drying gas fl capacity 2000 kbm / h. Circulation pressure drop approx. 1200 Pa. Fan work 2.5 kw. Temperature rise in gas fl fate 20 °. Heat supply including kt marriage work 14 kw. Dehumidification in the bed 18 kg / h. Bed weight approx. 270 kg. Drying 50% moisture ratio to 13% or 0.37x270 = 100 kg of water. i 00000 0 5 2 1 6: ".:: .z. '.:...: i 4 -; o' - rorhha ioo / is = 5,5 h ooh with heating ooh omhyro ov horohor = sh ooh adapted to a mentioned treski operation.

A heating of the first bed 1 to a working temperature of approx. 60 ° requires on the order of 18 kWh per sqm of bed area, which with the said heat output 14 kw takes 18/14 = 1.3 h. This amount of heat stored in the moist ice mass is not lost but is converted in dry steam during batch drying and moisture evaporation. The amount of heat substantially compensates for the said imbalance 2.5 W-3 W in drying power between the beds 1,2, which can thus be equated in mass and drying time.

With this data, the capacity will be 900 kg of dried ice per day and square meters of bed area. 7.5 m.

In reference to Figures 6 and 7, section 2 illustrates an embodiment of reclining surfaces 57 and box bottoms 43. The reclining surface comprises horizontal shelves 58 with widths substantially exceeding the height dimensions between the shelves, so that the beds 1,2 can rest on shelves without their inside edges. .

The shelves can suitably be made of plywood, eg in a size of 0.6 x 3 m, reinforced on the underside of triangular timber 59. The fact that fl ice embankments remain on the shelves when emptying the beds has no practical significance. The sloping surfaces 57 are inclined in pairs towards each other at said race angle.

In an easily mountable embodiment of the bottoms 43 of the boxes wetting towards the drying chamber, 45 denotes primary beams inclined at said race angle, supported by posts 46. The beams are made of wood with lower plywood ends as support for horizontally extended cassettes 47 of secondary beams and plywood beams. size 1.2 x 3 m. The cassettes are filled with fl ice. The plywood material forms a vapor barrier against the drying chamber 5 and the entire wooden structure is kept dry with the heat leakage from the chamber. The heat leakage is captured in the ice masses 31,32 of the boxes, which almost resets transmission losses from the drying chamber.

It can be pointed out that working temperatures in said alternative drying processes are not actively controlled in any way but adjust to iron weight positions depending on input heat output, on surface sizes and temperature gradients in heater 6 and heat exchanger 67, on surface size and vapor pressure gradient in diffusion air temperature 7 and outside diffusion temperature.

Claims (1)

1 526 216 S 'Patent claims. Drying device for raw ice or similar granulated material (3) comprising the material laid up batchwise in double beds (1,2) each permeated by drying gas den fats (1 1,21) circulated to further contact with heating means (6) and dehumidifying means (7)! in that it comprises double box-shaped boxes (41, 42) containing raw material (31) resp. dried material (32) and inclined towards the heating arm at a substantially racial angle for the material and thereby enclosing a section triangular drying nozzle (5), which accommodates the beds in the form of embankments over pressurized, chamber congruent triangular vented spaces (5 1,52) return ducts (5 3,54) for the drying gas fl destinies and that it further comprises conveyors (82,83, 84) for batchwise fl transfer of the material between boxes and beds. . Drying device according to claim 1, characterized in that it comprises said drying gas fl deserts (l 1,21) heated by an order of magnitude of 20 ° before entering the beds (1,2), the beds dried down with a high moisture ratio gradient and the dried material (32) mixed and prepared a required moisture equalization time in said box (42) for dried material. . Drying device according to claims 1 and 2, characterized in that it comprises said drying gas den deserts (1, 1.21) driven in closed cycles within the drying chamber (5) to vapor-separating contact with an exposed diffusion-insulating diffusion surface (7) against an outer lid. . Drying device according to claims 1 and 2, characterized in that it comprises a first said drying gas fl desolate (11) driven in a closed circuit within the drying chamber (5) in cooling, steam-separating contact to a heat exchanger surface (67) and reheated against said heater (6) and a in other words, drying gas fl destined to vapor-separating contact with a heat-insulating diffusion surface (7) exposed to the outer air and subsequent heating contact to the heat exchanger surface. . Drying device according to claims 1, 2 and 4, characterized in that it comprises fl electricity for said drying gas fl fate driven by internal combustion engines (9) with its engine heat and exhaust heat supplied first said drying gas fl fate (l 1). . Drying device according to claims 1-5 characterizes! in that it comprises said beds (1,2) heated, dried and replaced within a period of 8 hours and said boxes (41,42) dimensioned to each accommodate at least three times the bed volume.