Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
  • F26B11/02—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles
  • F26B11/028—Arrangements for the supply or exhaust of gaseous drying medium for direct heat transfer, e.g. perforated tubes, annular passages, burner arrangements, dust separation, combined direct and indirect heating
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10F—DRYING OR WORKING-UP OF PEAT
  • C10F5/00—Drying or de-watering peat

Definitions

• This invention relates to a method for drying a fibrous or granular material, preferably peat, in a rotary drier, primary drying air being supplied to the driver axially and being substantially moisture satur- ated at its passage through the drier due to absorp ⁇ tion of water from the material to be dried.
• the in ⁇ vention also comprises a device for drying a fibrous or granular material.
• a method and a device for drying wood chips and peat are previously known, the material being dried in a first space surrounding the space in which the final drying takes place.
• This two-step drying requires a relatively complicated device, the handling of the peat being relatively circumstantial as the peat must be transferred to the internal space for final drying after pre-drying in the external space.
• a device for continuous dewatering of peat is also known, where peat is supplied to a stationary, perforated drum, electric current being conducted through the peat, which will then give off water vapour, Air is fed into the drum, absorbs the water vapour and is pressed out through the perforations in the drum.
• Fig 1 is shown schematically a longitudinal section of a drying unit according to the invention and Fig 2 shows a section taken on the line II-II in Fig 1.
• the drying unit 1 shown in Figs. 1 and 2 comprises a rotary drier 2, which on its inside, see Fig 2, is provided with flanges 3, ensuring good stirring of the material placed in the drum 2.
• the drum 2 is prefer ⁇ ably cylindrical and has a great number of holes 4 on its mantle surface. These holes have preferably a dia etre of about 3 mm.
• the rotary drier 2 has aj ⁇ inlet opening 5 and a discharge opening.
• a great number of finned pipes 7 surround the drum 2 and are arranged at some distance from this.
• hot water or some other suitable medium is circulating in these finned pipes 7.
• the drum 2 is supported by two bearings 8, which have the shape of rings running about the drum 2.
• the drum 2 is rotatable within these bearings 8. This rotation is created by a drive source, e g an electric motor, and suitable transmitting means.
• An insulating mantle 9 is also included in the drying unit 1, which mantle extends along the major portion of the drum 2, the inlet and outlet openings 5 and 6 however not being surrounded by the mantle 9. As is apparent from Figs. 1 and 2 the mantle 9 has an up- wardly tapering inlet 10 for drying air.
• the drying unit described above works in the following way.
• the drying principle of the unit 1 is built on the fact that raw peat is dried in the rotary drier 2 by 5 evaporation of the water bound in the peat.
• the primary drying air supplied to the drum 2 - axially at the inlet opening has a relatively high temperature, about 150 C, when entering the drum 2.
• the supply of the primary drying air is preferably 10 carried out by means of a fan not shown in the figures.
• As the temperature of the primary drying air is so high a continuous disintegration of the particles takes place, the water in the particles being evaporated and taken up by the supplied drying air. * 15
• the drying air supplied at the inlet opening 5 absorbs water vapour its temperature will sink to the order of 70°C when the air leaves the drum 2 at the outlet opening 6. At this stage the primary drying air is almost moisture saturated.
• the drying air After the drying air has left the drum 2 via the outlet opening 6 it is dehydrated, e g in a heat ex ⁇ changer or condenser not shown in the figures. After this the secondary drying air is blown via fans or the like (not shown) into the mantle 9 through the inlet 25 opening 10.
• the secondary drying air When the secondary drying air is supplied to the mantle 9 after the de-moistening, its tempera ⁇ ture is down at about 50 C.
• hot water or the like is circulating in the finned pipes 7, the temperature of the hot water being of the order of 30 200 C.
• the hot water in the finned pipes 7 can e g consist of cooling water from some plant, waste heat thus being utilized for heating the drying air.
• the peat granulate obtained as the result of peat drying is extraordinarily well suited for automated solid fuel systems.
• the drying air used with the drying process according to the claimed invention can be obtained in many ways.
• a so-called hot air boiler is possible, which is e g fired with oil.
• This boiler has then preferably a water-carried cooling system.
• the heated air is used as primary drying air, but it can be mixed with the exhaust gases formed in the oil combustion. Cooling water from the boiler can be circulated in the finned pipes 7 for heating the secondary drying air. It is also possible within the scope of the in- vention that the secondary drying air is preheated in another way than through passage of the cam pipes.
• the temperature of the secondary drying air can e g be raised in such a way that it passes through a hot air boiler.
• the invention is of course by no means restricted to the illustrative example described above and considering the generation of the primary drying air in particular the variations are numerous. Thus, the invention can be freely varied within the scope of the accompanying drawings.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Drying Of Solid Materials (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20353751

Family Applications (1)

Country Status (5)

Citations (3)

• 1983
  • 1983-12-15 SE SE8306950A patent/SE441835B/sv not_active IP Right Cessation
  • 1983-12-15 SE SE8306950D patent/SE8306950L/xx not_active Application Discontinuation
• 1984
  • 1984-12-14 FI FI844964A patent/FI82860C/fi not_active IP Right Cessation
  • 1984-12-17 WO PCT/SE1984/000431 patent/WO1985002623A1/en active IP Right Grant
  • 1984-12-17 EP EP19850900250 patent/EP0168418B1/en not_active Expired
  • 1984-12-17 DE DE8585900250T patent/DE3473471D1/de not_active Expired

Patent Citations (3)

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